European Association for the Study of Diabetic Eye Complications

Annual Meeting Amsterdam May 30th to June 1st, 2008

Poster Abstracts

VARYING RETINOPATHY LEVELS WITHIN A NATIONAL SCREENING PROGRAMME. HOW MUCH IS ENOUGH ? A FIRST AUDIT

P.H. Scanlon, D.J. Taylor, F. O'Leary, D.M. Prentis

GHNHSFT, Cheltenham - United Kingdom

BACKGROUND. The English National Screening Programme for Diabetic Retinopathy is currently provided by 96 locally commissioned programmes. The regulation of these programmes is output based to a series of nationally applied quality standards. External quality assurance is now being put into place
and annual report data for the year 2006 2007 from 67 programmes has so far been analysed. Whilst natural variation in retinopathy levels is to be expected in programmes with differing age and ethnicity mixes, it was considered unlikely that the reported levels could be explained on that basis. The
range of diabetic retinopathy levels has been reported in a continuous distribution from 14 65% and within this distribution the levels of reported referable retinopathy also varied from 1% to 21%.

RESULTS/CONCLUSIONS. This study reports early audit of grading results within external quality assurance visits, for six programmes. It is concluded that despite careful drafting of grading criteria there is still variation between programmes on how the criteria are being interpreted and applied. This has been compounded in some instances by the way that services have configured reporting of retinopathy within their IT systems.

ARBITRATION GRADING AND REFERRAL IN DIABETIC RETINOPATHY SCREENING

K. Whitehouse¹, M.C. Clarke², R.E.J. Ryder³, B. Keown⁴, P.M. Dodson<sup>2

1</sup>Heart of England Foundation Trust, Birmingham - United Kingdom
²Heart of England NHS Trust, Birmingham - United Kingdom
³Sandwell and West Birmingham NHS Trust, Birmingham United Kingdom
⁴Digital Healthcare Cambridge, Cambridge - United Kingdom

PURPOSE. In the English National Screening Programme for Diabetic Retinopathy, following first and second full disease grading, differences of outcome and grades may occur. Arbitration grading is assessed across both grade and referral outcome to evaluate primary and secondary grading accuracy.

METHODS. Grading disagreements from Screeners, Graders and Optometrists over a 9 month period were reviewed by Arbitrators (KHW, RR, PMD, MC) based within Heart of England Diabetic Retinal Screening Centre (HEDRSC), South, Central and West Birmingham; data was compiled prior to and after the refresher grading training for Optometrists provided by HEDRSC. Results are analysed for grading consistency, and standards achieved. False positive diagnosis and missed sight threatening retinopathy is documented.

RESULTS. 525 arbitration episodes were analysed. 371 were due to first full disease and 127 second full disease grade error; with 27 complete disagreement on both grades by arbitration. 61 encounters (11 %) failed to identify referable sight threatening retinopathy (26 at first disease grade, 35 at secondary). 91 false referrals were identified (85 at first full disease grading). R1 (background retinopathy present) was falsely recorded on 173 first full disease and 28 second full disease grade encounters. Data from Heart of Birmingham and Solihull optometrists compiled 1 month prior to and post additional grading training resulted in a 51% reduction in arbitration grading confirming improved grading accuracy at all levels.
CONCLUSIONS. Arbitration grading across both clinical outcome and grade is necessary as a valuable and robust method of ensuring accuracy and detection of retinopathy, ensuring safety and detection of sight threatening retinopathy, whilst reducing unnecessary ophthalmology referrals.

A STUDY OF THE PATTERNS OF EARLY MAGNIFIED MACULA LESIONS TO ASSESS CLINICAL SIGNIFICANCE

R.L. Lone¹, M.C. Clarke¹, A.W. Wright², R.E.J. Ryder³, P.M. Dodson<sup>1

1</sup>Heart of England NHS Trust, Birmingham - United Kingdom
²Walsall Hospitals NHS Trust, Walsall - United Kingdom
³Sandwell and West Birmingham NHS Trust, Birmingham United Kingdom

PURPOSE/BACKGROUND. Observations from macular digital images of diabetic subjects have shown a number of subtle changes, the significance of which is unknown. Tiny microaneurysms are common but on magnification, a number demonstrate a pale circular rim (MAPCR) which could represent early lipid leakage which could lead to sight threatening clinical significant macular oedema (CSMO). In order to elucidate the nature and significance of these lesions, the authors investigate changes of early lesions in the macula with a six month follow up to identify how these lesions might change.

METHODS. Retinal images from patients with diabetes are used to identify spatial distribution of macula lesions, by means of a macula grid. All data including retinopathy grades, visual acuity and outcomes are recorded.

RESULTS. Out of 162 patients being monitored in the Ophthalmic Photographic Diabetic Review (OPDR) clinic, 75 have been re-photographed after six months, 17/75 (23%) have been referred to ophthalmology of which 2 have CSMO, 25/75 (33%) regressed and have been put back to annual recall and 33/75 (44%) continued in OPDR. The lesions were more commonly distributed in the inner region of the macula,
compared to the outer region.

CONCLUSIONS. The data suggests significance of these macula lesions, with over 60% of leakage and exudation (ophthalmology referral or continued to be re-photographed in OPDR) compared to less than 35% being put on annual review. This lesion of a MAPCR in many cases represents early exudative maculopathy.

IS RE-PHOTOGRAPHING PATIENTS A COST EFFECTIVE METHOD FOR MANAGING EARLY DIABETIC RETINOPATHY?

L.Q. Quant, R.L. Lone, A.W. Wright, M.C. Clarke, P.M. Dodson

Heart of England NHS Foundation Trust, Birmingham - United Kingdom

PURPOSE/BACKGROUND. Digital diabetic retinopathy screening programmes increase the cases of early diabetic retinopathy discovered that fit the national protocol for referral to ophthalmology.  Re-photographing outside the screening pathway in an Ophthalmic Photographic Diabetic Review (OPDR)
clinic, at a designated time period, is an alternative method of managing these cases. The purpose is to show the proportion of patients monitored in OPDR returning to annual screening or continuing in OPDR, is safe and cost effective as a method of reducing referrals to the hospital eye service.

METHODS. Patients with early diabetic retinopathy are re-photographed at a suitable period from 2-6 months. The images are compared to the initial photographs and graded as improved, unchanged or deteriorated. A consultant then decides whether to return the patient to annual screening, continue OPDR or refer to ophthalmology.

RESULTS. From January 1st 2007 to the end of March 2007, 120 referrals were made to ophthalmology, of which 54/120 (45%) images with significant early retinopathy were assessed and followed up in OPDR. 34/54 (63%) have been reviewed so far. 13/34(38%) were returned to annual screening, 19/34 (56%) continued in OPDR and 2/34 (6%) were referred to ophthalmology. Without OPDR all 34 would have been
seen in hospital eye clinics costing approximately 3,298. With OPDR, the total cost was in the order of £1,214, making the total saving in the order of £2,084. 32 ophthalmology appointment slots were also made free.

CONCLUSIONS. OPDR clinics are a safe, cost effective method of reducing the referral burden in ophthalmology from implementing a new retinopathy screening programme.

DETECTION OF EARLY STAGES OF DIABETIC MACULAR EDEMA

G. Tremolada¹, R. Lattanzio¹, L. Pierro¹, G. Maestranzi¹, M. Lorenzi<sup>2

1</sup>San Raffaele Scientific Institute, Milano - Italy
²Schepens Eye Research Institute, Harvard Medical School, Boston - USA

PURPOSE. Currently, DME is treated when is fully developed and sight-threatening; and interventions are seldom curative. Seeking to identify preclinical stages of DME might yield useful markers, new insights into pathogenesis, and eventually preventative approaches. Aim of this study was to identify early abnormalities predictive of DME as detected by Spectral-OCT.

METHODS. During the period October/December 2007, we evaluated 28 consecutive diabetic patients with levels 20-35 in the ETDRS retinopathy scale but neither symptoms nor signs of DME. For each patient we recorded age, gender, diabetes type, duration and treatment, recent HbA1c value and history of hypertension. All patients underwent complete ophthalmological examination and Spectral-OCT. A library of macular images obtained by Spectral-OCT in age-matched individuals without diabetes or retinal diseases was evaluated in parallel.

RESULTS . The type 1 diabetes group included 17 patients (31 eyes), 5F/12M. Age range was 11-38 years, (QUERY: Are ranges correct throughout abstract?) diabetes duration 9.7-17.3 years, HbA1c 81.5%; hypertension in 23.5%, ETDRS-20: 6 eyes. OCT showed foveal thickness 223.9±29.7 (QUERY: is ± correct here and throughout abstract?) microns, and in 6/25 eyes with ETDRS-35(24%) small iporeflective zones in the inner nuclear layer appearing as microcysts. In the type 2 diabetes group (11 patients, 19 eyes; 7F/4M; age 61.79, diabetes duration 10.7±6.5, HbA1c 7.61.6%, hypertension in 63.6%, ETDRS-20: 2 eyes) foveal thickness was 280.2±87.3 microns, and microcysts were present in 16/17 eyes with ETDRS-35(94.1%). No such images were detected in the controls.

CONCLUSIONS. Retinal abnormalities with the appearance of microcysts are detectable in eyes with retinopathy level ETDRS-35 and no clinical DME, with prevalence higher in type 2 than in type 1 diabetes. Further studies and longitudinal follow up will clarify if the abnormalities are part of the natural history of DME.

INDIVIDUALISATION OF SCREENING INTERVALS REQUIRES CONSIDERATION OF RISK FACTORS OCCURRING OVER TIME AND DIFFERENCES IN RISK RELATED TO SEX

M.J. Mehlsen¹, M. Erlandsen², P. L. Poulsen³, T. Bek<sup>1

1</sup>Aarhus University Hospital, Aarhus - Denmark
²Dept. of Biostatistics, Aarhus University, Aarhus - Denmark
³Medical Dept. M, Aarhus University Hospital, Aarhus - Denmark

BACKGROUND. Vision threatening diabetic retinopathy is discovered by fundus photographic screening. The screening interval is defined on the basis of diabetes type, duration of the disease and retinopathy so that patients with aggressive disease progression are detected. However, having standardized screening intervals implies that patients with slow disease progression will experience superfluous examinations. This may be optimized by individualizing screening intervals on the basis of the patients' individual risk factors. The authors therefore set out to build a screening model for optimizing intervals for screening for diabetic retinopathy by including other risk factors, such as HbA1c and blood pressure, in the decision making.

METHODS. Data from 31,590 screening examinations, 81.228 measurements of HbA1c and 16.189 blood pressure measurements in 10.039 diabetic patients (2274 type 1 and 7765 type 2) followed since 1994 were included in a decision model based on methods from survival analysis and cox-regression. The present study reports the input data to the model.

RESULTS. Mean artery pressure decreased 0.85mmHg/year from baseline = 103.8mmHg for women and 0.97mmHg/ year from baseline = 106.5mmHg for men (p<0.001) for both trends. HbA1c decreased in type 1 diabetic patients: from 8.4% to 8.2% in women and from 8.9% to 8.5% men, and in type 2 diabetes: from 8.9% to 8.0% in women and from 8.5% to 7.9% in men (p<0.001 for all comparisons). Using a modified ETDRS grading scale there was no significant difference in the retinopathy grade between the two sexes. (Pearson correlation, p-value = 0.22.). There was a significant overrepresentation of men among type 2 diabetic patients in the data set (4449 men vs 3397 women, p< 0.01), but no difference among the type 1 diabetic patients (1174 vs 1082, p=0.06). Furthermore, after 30 years duration of type 1 diabetes men had been treated more frequently than women (55% of men vs 65% of women, Kaplan-Meyer plot).
CONCLUSIONS. It is possible to develop an individualized screening system including other variables than diabetes type, duration and retinopathy grade. These models should take into account changes in risk factors occurring over time and differences in risk of developing retinopathy related to sex.

PREVALENCE OF VASCULAR RISK FACTORS IN PATIENTS ATTENDING A DIABETIC EYE SCREENING PROGRAMME: PRIMARY VERSUS SECONDARY CARE

N. Collaer¹, A.C. Fisher², S.P. Harding¹, J.P. Vora³, D.M. Broadbent<sup>3

1</sup>St. Pauls Eye Unit, Royal Liverpool University Hospital - United Kingdom
²Department of Clinical Engineering, Royal Liverpool University Hospital - United Kingdom
³Department of Diabetes and Endocrinology, Royal Liverpool University Hospital - United Kingdom

PURPOSE/BACKGROUND. Control of glucose, blood pressure (BP) and cholesterol can slow progression of retinopathy. The authors aimed to assess the control of vascular risk factors for morbidity in diabetic patients attending a retinopathy screening programme, under either primary (PC, general practitioner and
practice nurse) or secondary (SC, hospital endocrinologist) care.

METHODS. Cross-sectional observational study on patients screening positive for sight-threatening diabetic retinopathy (STDR, defined as moderate pre-proliferative retinopathy or greater and/or ciricinate maculopathy or exudates within one disc diameter of centre of the fovea), ungradable images or other significant eye disease in either eye and consequently attending for slit-lamp biomicroscopy. Data were collected on demography, glycaemic control (HbA1c), blood pressure (BP) and dyslipidaemia and compared to national targets. Poor glycaemic control was defined as HbA1c >8%. Undiagnosed hypertension was defined as systolic >140mmHg and/or diastolic >90mmHg. Targets in known hypertension: type 1 130/80mmHg, type 2 140/80mmHg. Total random cholesterol (TC) target was <5mmol/L.

RESULTS. 1447 patients attended between June 6, 2006 and September 1, 2008: mean age 66.5 (21-93) yrs; mean duration of diabetes 8.9 (<1-50) yrs; 131 type 1 (3.4% PC: 25.8% SC) and 1263 type 2 (96.6% PC: 74.2% SC). HbA1c, BP and TC results were available for 823, 1385 and 706 patients respectively.

	Primary care mean ± SD		Secondary care mean ± SD
	Type 1	Type 2	Type 1	Type 2
HbA1c (%)	7.6±1.7	7.2±1.6	7.6±1.7	7.5±1.6
Systolic BP (mmHg)	151±20	145±22	145±20	145±21
Diastolic BP (mmHg)	81±19	78±31	81±13	79±13
Total cholesterol (mmol/L)	4.3±0.84	4.0±1.1	4.2±1.3	3.9±1.1
	Primary care targets failed (%)		Secondary care targets failed (%)
	Type 1	Type 2	Type 1	Type 2
HbA1c	18.8	20.1	29.7	27.7
BP	42.9	51.0	65.2	68.8
Total cholesterol	21.4	12.7	18.2	11.7

CONCLUSIONS. This study provides useful current estimates of prevalence during a time of changing diabetes management. Risk factors appear to continue to be poorly. (QUERY: Please complete sentence)

PREVALENCE OF VASCULAR RISK FACTORS IN SIGHTTHREATENING DIABETIC RETINOPATHY IDENTIFIED IN A RETINOPATHY SCREENING PROGRAMME

N. Collaer¹, A.C. Fisher², S.P. Harding¹, J.P. Vora³, D.M. Broadbent<sup>3

1</sup>St. Pauls Eye Unit, Royal Liverpool University Hospital - United Kingdom
²Department of Clinical Engineering, Royal Liverpool Univer- sity Hospital - United Kingdom
³Department of Diabetes and Endocrinology, Royal Liverpool University Hospital - United Kingdom

PURPOSE/BACKGROUND. To assess vascular risk factors in patients with sight threatening diabetic retinopathy (STDR) identified from a primary care based retinopathy screening programme.

METHODS. Cross-sectional observational study on patients screening positive for STDR (defined as moderate pre-proliferative retinopathy or worse and/or circinate maculopathy or exudates within one disc diameter of centre of fovea), ungradable images or other significant eye disease in either eye and consequently attending for slit-lamp biomicroscopy by retinal specialists. Data were collected on demography, glycaemic control (HbA1c), blood pressure (BP) and dyslipidaemia and compared to national targets. Poor glycaemic control was defined as HbA1c >8. Undiagnosed hypertension was defined as systolic >140mmHg and/or diastolic >90mmHg. Targets in known hypertension: type 1 130/80mmHg; type 2 140/80mmHg. Total random cholesterol (TC) target set <5mmol/L.

RESULTS. 1447 patients attended between June 6, 2006 and August 1, 2008. 21% of patients had STDR, of whom 21% had type 1 and 78% type 2 diabetes. Mean age was 66.5 (21-93) yrs; mean duration of diabetes 8.9 (<1-50) yrs.

	STDR		non-STDR
Risk Factor	mean ± SD	% Target failure	mean ± SD	% Target failure
HbA1c (%)	8.35 ± 2.10	50	7.13 ± 1.50	17
Diastolic BP (mmHg)	79 ± 12	14	78 ± 29	14
Systolic BP (mmHg)	144 ± 23	52	145 ± 23	56
Total cholesterol (mmol/L)	4.3 ± 1.3	27	4.0 ± 0.9	16

Statistical analysis using the Kolmogorov-Smirnov test (α<0.05, one-sided) showed STDR to be related (H0=1) to HbA1c (strongly), and to cholesterol and diastolic BP, but not related (H0=0) to systolic BP.

CONCLUSIONS. Vascular risk factors appear poorly controlled in patients with STDR, with the mean HbA1c being significantly higher than current targets. Uncontrolled glycaemia seems to be most strongly correlated with the presence of STDR and requires particular attention in pathways of patient care.

DUTCH PATIENTS' INCENTIVES AND BARRIERS TO PARTICIPATING IN DIABETIC RETINOPATHY SCREENING

K.N.D. van Eijk ¹, Y. Groeneveld ², W.J.J. Assendelft ², J. Gussekloo <sup>2

1</sup>Oegstgeest - The Netherlands
²LUMC, Leiden - The Netherlands

BACKGROUND. In the Western world diabetic retinopathy is one of the most important causes of acquired visual impairment and blindness among adults up to 65 years. Because 80% of this can be prevented with laser-coagulation, early detection of diabetic retinopathy by means of screening is necessary. Nevertheless, optimizing compliance to this retinopathy screening is shown to be difficult. The authors assessed the prevalence of participation in diabetic retinopathy screening among patients with diabetes in Dutch general practices and investigated patients incentives and barriers to participating.

METHODS. A questionnaire was sent to all patients (aged 18 years and over) with a diagnosis of diabetes enlisted in 20 general practices (n=3241). This questionnaire asked for participation in retinopathy screening in the last 3 years and for the relevance of incentives and barriers to participating.
An inventory of these incentives and barriers was made by analysis of five focus-group interviews with patients with diabetes. These were attended by both participants and nonparticipants in screening, both urban and rural living patients, including immigrants and active members of the Dutch Diabetes Association.

RESULTS. In total 2051 patients (response 63.3%) participated in our study, of which 1688 (82.3%) had attended retinopathy screening in the last 3 years and 363 (17.7%) had not. No differences in participation were found between men and women (86.5% vs. 86.8%, p=0.822). Participation did not increase with age (p=0.913). Participation was higher among high educated patients with diabetes compared to low edu-
cated patients (87.5% vs. 78.9%, p=0.003). Focus-group results showed motivational factors to consist of 3
domains, being sense of duty, medical considerations and fear. Lack of knowledge, doubting medical necessity, practical inconveniences (e.g. immobility and long waiting time), fear and religious grounds were reasons not to attend screening. Quantitative analyses of these incentives and barriers are currently performed.

CONCLUSIONS. 17.7% of Dutch patients with diabetes in general practices did not participate in retinopathy screening in the last 3 years. Clues to raise compliance are both emphasizing incentives and intervening in barriers. Quantitative data regarding the relevance of several incentives and barriers will
be presented at the congress.

IMPACT OF PATIENTS' AND PHYSICIANS' ATTITUDES ON DIABETIC RETINOPATHY IN TYPE 1 DIABETES: 3 CASE REPORTS

L. Prochazkova, M. Zavorkova

Masaryk Hospital, Usti Nad Labem - Czech Republic

PURPOSE. Evaluation of patients and physicians attitudes to diabetic retinopathy in type 1 diabetes.

METHODS. Distinct attitudes are shown in three case reports. The authors study the history, ophthalmological examination, treatment and outcome.

RESULTS. Case 1: female, born 1978, diabetes since 1982, regularly monitored at our department since 1986. First symptoms of diabetic retinopathy (DR) in 2004, visual acuity (VA) 5/10, 5/7.5, proliferative bilateral DR found, panretinal photocoagulation carried out. Got pregnant in 2006 after a consultation, has an insulin administration device. Photocoagulation spots continuously supplemented. Confinement in February 2007. Autumn 2007 VA 5/5, 5/5 with a correction, findings stabilized. Case 2: male, born 1957, diabetes since 1970, regularly monitored in his home. In September 2007, visits due to deteriorating visual acuity on the left eye. VA 5/7.5, 1/50. Bilateral proliferative diabetic retinopathy with a total traction detachment found on the left. A panretinal photocoagulation performed on the right and a pars plana vitrectomy on the left. Autumn 2007 VA 5/10, 1/50, on the left the finding stabilized, the retina is lying, but the VA does not improve. Case 3: male, born 1987, diabetes since 1991, regularly monitored by his physician, first symptoms of DR in 2004. Focal photocoagulation begun in July 2006. VA then 5/10
and 5/7.5. Inappropriate job as a cook. Does not observe the diet, diabetes subcompensated, refuses an insulin administration device. In January 2007 renal functions decompensated and secondarily ophthalmologic findings to proliferative DR bilaterally, panretinal photocoagulation launched. In Au-
gust a hemophthalmus on the left, 2 months later a PPV carried out, VA 5/15 and 1/30.
DISCUSSION. Patient 1, perfect cooperation of the patient with her physician. Patient 2, what has the physician been studying during the examinations? Patient 3, one can not help those who will not follow advice.

CONCLUSIONS. Optimal cooperation between physician and patient helps avoid serious complications. On the other hand, lack of cooperation leads to substantially faster progress of complications. The worst situation occurs when the patient attends the examinations but the physician fails to notice the progress of the finding.

WHITE SPOTS IN THE MACULA OF PATIENTS WITH DIABETES MELLITUS TYPE 1, WITHOUT OR WITH MINIMAL DIABETIC RETINOPATHY, EVALUATED WITH SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY

P.H.B. Kok, H.W. van Dijk, C. Biallosterski,

R.O. Schlingemann, F.D. Verbraak Academic Medical Center, Amsterdam - The Netherlands

PURPOSE/BACKGROUND. To evaluate white spots seen in the macula of patients with diabetes mellitus (DM) type 1, without or with minimal diabetic retinopathy (DR) with spectral domain optical coherence tomography (SD-OCT).

METHODS. Forty-five patients with DM type 1, without or with minimal DR on biomicroscopy, underwent a full ophthalmologic examination, including best-corrected VA, slitlamp examination, funduscopy, (red-free) fundus photography and OCT scanning of the macula. At the same day, HbA1c, blood pressure and to-
tal cholesterol were measured. Small white spots (diameter 10 micron) seen on (red-free) fundus photography scattered around the fovea were examined on corresponding B-scan images using SD-OCT (3D OCT-1000, Topcon).

RESULTS . Ninety eyes of 45 patients were included in the study. Fundus photography showed white spots in the central fundus in 39 eyes (28 patients), the median number of spots per eye was 5, range 1 to 50. High definition b-scan images corresponding with the localization of the white spots showed hyperreflective lesions at the level of the retinal nerve fiber layer (RNFL). There was no correlation found between the presence of white spots and the presence of DR, nor with high blood pressure, HbA1c or total cholesterol.

CONCLUSIONS. White spots seem to be a common occurrence in the retina of patients with DM type 1, without or with minimal DR. Previous studies located these white spots at the level of the retinal pigment epithelium, based on stereoscopic slitlamp examination. In contrast, the authors localized the
white spots at the level of the RNFL using the SD-OCT. This implicates that these white spots are not small depigmented lesions of the RPE. Their true nature is still unclear.

CENTRAL SEROUS CHORIORETINOPATHY AND DIABETES: THE MISSING LINK

A.R. Kulkarni, D.R. Seneviratne, S.E. El-Sherbiny

Birmingham and Midland Eye Centre, City Hospital, Birmingham - United Kingdom

PURPOSE. This consecutive case series aimed to establish the etiopathological role of diabetes in the development of central serous chorioretinopathy (CSCR) and to aid early visual recovery.

METHODS. Four consecutive patients presenting with CSCR and found to have diabetes were included in this 12-month study at a major teaching hospital. They underwent thorough ophthalmic assessment, optical coherence tomography (OCT) and fundus fluorescein angiography (FFA) which showed the classic leakage within the neurosensory detachment.

RESULTS. Subretinal fluid of varying degree and pigmentary disturbances in the macula were noted in all cases and CSCR was confirmed by OCT and FFA. Three of the four patients had recent onset of diabetes. One of these had pregnancy induced diabetes at the onset of CSCR. The fourth patient was a known diabetic with recently uncontrolled sugar levels which coincided with the onset of his visual symptoms
of CSCR. None of the patients had diabetic retinopathy with the onset of the CSCR.

CONCLUSIONS. CSCR was thought to be idiopathic in aetiology and run an unpredictable course. It has been associated with the young, stressed male prototype. It has also been associated with higher levels of cortisol which influence the retinal pigment epithelium junctions, allowing breaks and the devel-
opment of CSCR. Higher levels of cortisol are found in stress, diabetes and pregnancy, which could be the missing aetiological link for the development of CSCR. To our knowledge this is one of the few series correlating the aetiopathology of CSCR with diabetes. CSCR could be an early manifestation of diabetes emphasizing the importance of early detection and treatment of diabetes and hence the early res-
olution of CSCR.

CHANGES IN THE ANTERIOR CHAMBER ANGLE IN DIABETIC PATIENTS WITH SECONDARY NEOVASCULAR GLAUCOMA USING OCT VISANTE

L. Prochazkova, M. Zavorkova

Masaryk Hospital, Usti Nad Labem - Czech Republic

PURPOSE. To document the changes in the anterior chamber angle in diabetic patients with secondary neovascular glaucoma (SNVG) using OCT Visante.

METHODS. OCT Visante (anterior segment optical coherence tomography) is an imaging technology enabling anterior segment evaluation including corneal thickness and anterior chamber angle anatomy. The clinical sign of SNVG is rubeosis iridis with elevated intraocular pressure (IOP). The authors examined the anterior segment in diabetic patients with SNVG using OCT Visante and, subsequently, assessed
corneal thickness, anterior chamber depth, and potential angle adhesion. The authors compared findings with the other eye of the patient. The examination is noninvasive, noncontact, and without mydriasis.

RESULTS. The thickness of the cornea was bigger in the eyes with SNVG than in the other eyes. The worst finding proved 976 microns thickness of the cornea in its centre (nearly twice the thickness in comparison with the other eye). The depth of the anterior chamber firstly depends on whether the patient is phakic or pseudophakic, and secondly on the presence of adhesions in a chamber angle. In the eyes with SNVG and with the adhesions in an angle, the anterior chamber was in all cases shallower than in the other eye. One of the patients from the group, who has SNVG on both eyes, showed the following: the depth of his right anterior chamber was 1,92, the left 2,12. In the right eye, where the anterior chamber was shallower, the clinical finding was worse, the atrophy of the iris was bigger and there were more adhesions in the angle.

CONCLUSIONS. OCT Visante is very helpful in diagnostics and in monitoring the changes of the angle in diabetic patients with SNVG. The authors can measure the angle, document in all sections and evaluate in the course of time. The authors always compare the finding in an angle with gonioscopy. During gonioscopy, a problem may arise when a physician presses the cornea and this pressure opens an angle. This is why gonioscopy with the use of OCT Visante is revolutionary it can never be distorted.

THE DIFFERENCE IN FOCAL PHOTOCOAGULATION TREATMENT OF CLINICALLY SIGNIFICANT MACULAR EDEMA DIAGNOSED WITH OCT VERSUS SLITLAMP BIOMICROSCOPY.

H.W. Van Dijk¹, P.H.B. Kok¹, R.O. Schlingemann¹, M.D. Abramoff ², F.D. Verbraak<sup>1

1</sup>Academic Medical Center, Amsterdam - The Netherlands
²University of Iowa Hospital and Clinics, Iowa City - USA

PURPOSE. To evaluate the difference in focal photocoagulation treatment of clinically significant macular edema (CSME) diagnosed with StratusOCT versus stereo slitlamp biomicroscopy.

METHODS. Twenty-five eyes of 16 diabetic patients with a clinical suspicion of CSME were examined by stereo slitlamp biomicroscopy and StratusOCT to determine the exact location and extent of the possible CSME. Results of these observations were drawn into a set of FA images (early/mid/late phase) and color fundus photographs. Based on these images, observers, masked for the method of assessment of CSME, marked the position, pattern, and number of laserspots on the corresponding color photograph.

RESULTS. The authors found a difference in location and extent of CSME in 11 eyes (44%) comparing StratusOCT with stereo slit-lamp biomicroscopy. Treatment decisions based on these different observations differed substantially with respect to the amount and localization of the laserspots.

CONCLUSIONS. The focal photocoagulation treatment for CSME based on StratusOCT differs from the focal photocoagulation treatment based on stereo slitlamp biomicroscopy with respect to the amount and localization of the laser spots. Future studies need to address whether this difference has clinical relevance.

ANTI-VEGF THERAPY IN NEOVASCULAR GLAUCOMA

J. Conrath¹, O. Prost-Magnin¹, F. Matonti¹, L. Hoffart¹, P. Massin<sup>2

1</sup>Hôpital de la Timone, Marseille - France
²Hôpital Lariboisière, Paris - France

PURPOSE. To describe the management of neovascular glaucoma by intravitreal injection of anti-VEGF molecules.

PATIENTS AND METHODS. Nine eyes of 9 patients presenting with neovascular glaucoma secondary to proliferative diabetic retinopathy (6 eyes) or retinal vein occlusion (3 eyes) were treated by intravitreal injection of bevacizumab (6 eyes) or ranibizumab (3 eyes).

RESULTS. Initial average IOP was 42.9 mmHg (ranging from 25 to 66 mmHg), and at 1 month it decreased to an average of 23.8 mmHg (ranging from 10 to 50). Fluorescein angiography of the iris showed decrease of leakage. Three cases were unsuccessful due to secondary obstructive glaucoma with irreversible fibrovascular tissue present in the iridocorneal angle. They were subsequently treated by diode laser cyclophotodestruction (2 eyes) or trabeculectomy (1 eye).

DISCUSSIONS. VEGF is implicated in development of prepapillary, preretinal and iris neovascularization. In this study, in spite of short follow-up, anti-VEGF therapy showed promise in treating iris neovascularization. A larger, randomized trial may provide guidance on precise timing and frequency of injections.

INTRAVITREAL TRIAMCINOLONE INJECTION FOR DIABETIC MACULAR OEDEMA

J.W.M. Reichert-Thoen

VU University Medical Center, Amsterdam - The Netherlands

PURPOSE/BACKGROUND. Treatment of diabetic macular oedema with laser is not always possible or successful. The authors describe results of intravitreal triamcinolone injection in these patients.

METHODS. Prospective trial, in which patients were given 4 mg of triamcinolone by intravitreal injection, with minimum follow-up of 3 months.

RESULTS. In 22 eyes (18 patients) with diabetic macular oedema (OCT >250 micron) and visual acuity <0.5, in which laser therapy was unsuccessful, or impossible, mean visual acuity was 0.25 (Snellen) before injection. Three months after the injection, mean visual acuity was 0.31. Mean central macular thickness was 506 micron before injection, 333 micron after 3 months. In 43% of eyes intraocular pressure was >22 mmHg after the injection; in only one eye intraocular pressure was > 30 mmHg. Medical therapy was sufficient to lower intraocular pressure. There were no other complications.

CONCLUSIONS. Intravitreal triamcinolone injection is a successful treatment for diabetic macular oedema in the short term.


INTRAVITREAL TRIAMCINOLONE ACETONIDE AND BEVACIZUMAB IN DIABETIC MACULAR EDEMA TREATMENT

N.N. Grigoryeva¹, Y.S. Astakhov ², F.E. Shadrichev¹, N.Y. Dahl ², E.B. Shklyarov<sup>1

1</sup> Regional Diabetical Center, Saint-Petersburg - Russian Federation
²State Medical University, Saint-Petersburg - Russian Federation

PURPOSE. To assess the effect of intravitreal injections of Triamcinolone Acetonide and Bevacizumab combined with laser coagulation on the diabetic macular edema (DME).

METHODS. 137 eyes of 103 patients with DME were enrolled into two groups: 1st- 75 patients (96 eyes) who received 4 mg of intravitreal triamcinolone acetonide (IVT group) and 2nd - 28 patients (41 eyes) who received 1.25 mg of intravitreal bevacizumab (IVB group). All patients underwent modified grid laser coagulation after injections. Central macular thickness (CMT), total macular volume (TMV), measured by
optical coherence tomography, and visual acuity (VA) were assessed. The follow-up time was 9-12 months for IVT group and 6 months for IVB group.

RESULTS. Maximum VA improvement was in 3 months for IVT group and in 1 month for IVB group (IVT group: VA at baseline 0.27, at 1 month 0.32, at 3 months 0.33, at 6 months 0.29, at 9 months 0.20, at 12 months 0.20; IVB group: VA at baseline 0.28, at 1 month 0.35, at 3 months 0.31, at 6 months 0.29). In both groups decrease of CMT and TMV was registered by OCT during the follow-up period, the most evident one being at 1 month after injections: IVT group: mean CMT (microns)/TMV (mm³) at baseline 519.3/10.8, at 1 month 343.6/ 8.9, at 3 months 353.3/ 8.8, at 6 months 416.9/ 9.6, at 9-12-months 399.1/ 9.6, correspondingly; IVB group: mean CMT (microns)/TMV (mm³) at baseline 497.6/9.8, at 1 month 360.1/8.4, at 3 months 381.1/8.4, at 6 months 387.4/ 8.6, correspondingly. IOP elevation was noticed in 37.6% of the
IVT group.

CONCLUSIONS. Intravitreal injections of triamcinolone acetonide or bevacizumab in combination with retinal laser coagulation may be an effective treatment of DME.

LANREOTIDE AUTOGEL FOR PERSISTENT DIABETIC MACULAR EDEMA: A PROSPECTIVE STUDY OF EFFECTIVENESS AND QUALITY OF LIFE

E.S. Soto-Pedre¹, M.C. Hernaez-Ortega², J.A. Piniés<sup>2

1</sup>European Innovative Biomedicine Institute, Castro-Urdiales - Spain
²Hospital of Cruces, Baracaldo (Vizcaya) - Spain

PURPOSE. To evaluate the effectiveness of the somatostatin analogue lanreotide Autogel in patients with persistent diabetic cystoid macular edema (CME) and their quality of life.

METHODS. Case series, prospective study. Two patients treated with a deep subcutaneous injection of lanreotide Autogel of 90 mg every 4 weeks were monitored at baseline and at 3, 6 and 12 months. Each patient had a complete medical examination including an upper abdominal ultrasound screening for gall
bladder disease, best visual acuity (VA) measured by the logMAR chart, and foveal thickness that was documented using Optical Coherence Tomography (OCT). Data on age, sex, diabetes mellitus, and health-related quality of life (SF-12 and VF-14 questionnaires) were also collected.

RESULTS. One year later stabilization of VA was observed in all eyes, and foveal thickness decreased by 38.2% on average by OCT. The SF-12 mental health domain increased in both patients getting closer to population norms, and visual functioning improved by VF-14. The adverse reactions were mild and subsided after 3 months of treatment.

CONCLUSIONS. Monthly subcutaneous injections of lanreotide Autogel offered an effective treatment alternative in patients with persistent diabetic CME and poor glycemic control.

VITRECTOMY IN THE TREATMENT OF DIABETIC MACULAR OEDEMA

J. Kalvoda, J. Duskova, B. Kalvodova

Charles University in Prague 1st Faculty of Medicine / General Teaching Hospital, Prague - Czech Republic

PURPOSE. To evaluate the efficiency of vitrectomy with peeling of the internal limiting membrane (ILM) in eyes with chronic diffuse and/or cystoid type of diabetic macular oedema and to perform ultrastructural histopathologic and morphometric analysis of the ILM.

METHODS. The prospective study involved 56 eyes of 52 diabetic patients mean age 63±7.6 years. These patients were operated between January 2006 and June 2007. Vitrectomy with trypan blue associated peeling of the ILM was performed in a standard way. Mean period of observation of patients after vitrectomy was 8.7 months. The ILM was fixed immediately after peeling in 2.5% glutaraldehyde and submitted for electron microscopic evaluation. The ILM was photographed in standard magnification (x 5 000) with the scale of 1 m in the shot.

RESULTS. Statistical analysis proved general improvement of the post-operative visual acuity (VA) with the prevalence of the resulting VA in intervals 0.1, 0.2 and 0.5±1.0 (related to ETDRS table). Morphometric analysis demonstrated a significant thickening of the ILM in all eyes with a mean thickness of the ILM 3.61±0.91 m.

CONCLUSIONS. Vitrectomy with peeling of the ILM in eyes with chronic diabetic macular oedema mildly improves the VA and extends hope for its stabilization. Morphometric and histopathologic analysis of the ILM contributes to more objective evaluation of ultrastructure of the vitreomacular interface.

25-GAUGE VITRECTOMY AS THE GOLD STANDARD FOR SEVERE PDR AND MACULAR EDEMA

F.M. Forlini¹, B.A. Bratu², R.P. Rossini³, B.F. Badala³, F.C. Forlini<sup>3

2</sup>SMCB Clinic, Bucharest - Romania
³Ravenna Hospital, Ravenna - Italy

PURPOSE. To examine whether 25-gauge vitrectomy might be a good approach for treatment of severe proliferative diabetic retinopathy (PDR) and macular edema.

METHODS. 31 patients with severe PDR and macular edema were randomized to either 20 or 25-gauge vitrectomy. The 25-gauge vitrectomy was performed with bimanual technique, 27-gauge chandelier illumination, Tano diamond dusted scraper. Sixteen patients underwent 25-gauge vitrectomy.

RESULTS. Incidence of complications like iatrogenic retinal tears and bleeding were significantly less in the 25-gauge vitrectomy group when compared to the 20-gauge vitrectomy group. The efficacy between the two techniques was similar. The 25-gauge vitrector was used to cut fibrinous tissue with high accuracy and was found to replace well curved scissors usually used with the 20-gauge technique.

CONCLUSIONS. 25-gauge vitrectomy might represent the gold standard for treatment of severe pdr and macular edema.

THE POTENTIAL ROLE OF URIC ACID IN PATHOGENESIS OF DIABETIC RETINOPATHY

L. Kotilova¹, M. Kalousova², A. Kubena³, B. Kalvodova<sup>1

1</sup>Dept. of Ophthalmology, General Teaching Hospital Charles University, Prague - Czech Republic
²Dept. of Biochemistry, General Teaching Hospital Charles University, Prague - Czech Republic
³Faculty of Pharmacy, Charles University, Prague - Czech Republic

PURPOSE. To evaluate the influence of impaired vascular permeability in diabetic retinopathy (DR) on vitreous levels of biochemical analytes.

METHODS. During pars plana vitrectomy undiluted vitreous samples were obtained from 55 patients with nonproliferative DR (NPDR), 24 patients with proliferative DR (PDR) and 48 controls with nondiabetic ocular disease. Simultaneously venous blood samples were obtained. Biochemical analytes levels (HbA1c, uric acid, glucose, electrolytes) were estimated by standard clinical chemistry methods.

RESULTS. Uric acid (UA) levels both in serum and vitreous were significantly higher in diabetic patients than in controls (p<0.001 serum; p=0.024 vitreous). Type of DR correlated significantly with UA vitreous levels, which was higher in PDR (p=0.012). The authors observed that UA vitreous level is not
related to HbA1c, duration of diabetes, type of diabetes, or insulin therapy. Leakage rate of UA through blood-retinal barrier (BRB) is 1.876 times higher in patients with DR than without DR (p<0.001) and 1.168 times higher in patients with PDR than with NPDR (p=0.03).

CONCLUSIONS. The results of our study suggest that increased level of uric acid present in serum and vitreous of diabetic patients may contribute to the pathogenesis and progression of DR. UA may influence vascular endothelial dysfunction and increase permeability at PDR. These findings present opportunities for novel modalities in prevention of DR.

SHORT TERM DYNAMIC CHANGES IN THE RETINAL MICROCIRCULATION ARE INVOLVED IN THE PATHOGENESIS OF DIABETIC RETINOPATHY

T. Bek

Aarhus University Hospital, Aarhus - Denmark

BACKGROUND. The pathophysiology of diabetic retinopathy is unknown, but it is assumed that disturbances in retinal blood flow including reduced autoregulation are a central part of the disease pathogenesis. However, diabetic retinopathy is characterized by a predominance of lesions corresponding to the microcirculation far away from the blood pressure trauma, and a fast turn-over of retinal lesions which may be a central phenomenon in the disease pathogenesis. Therefore, there is a need for studying dynamic changes in retinal blood flow and the resulting dynamic changes in retinopathy lesions.

METHODS. Six diabetic patients were scheduled every other week during 6 months for measurement of visual acuity, fundus photography, and measurement of the risk factors blood pressure, blood glucose and HbA1c. The fundus images were aligned, and changes in retinal morphology were related to known risk factors for developing diabetic retinopathy.

RESULTS. There was no relation between the short-term dynamic changes in retinal lesions occurring within weeks and known risk factors for developing diabetic retinopathy that only changed minimally within the study period (p>0.05 for all comparisons). The results and possible explanations for the findings are demonstrated by playing movies of the observed dynamics of vascular lesions in diabetic retinopathy.

CONCLUSIONS. Other factors than disturbed autoregulation and blood glucose control are co-involved in the pathogenesis of diabetic retinopathy. There is a need for elucidating short term dynamic phenomena in the retinal blood flow responsible for the dynamic turn-over of diabetic retinopathy lesions.

N-METHYL-D-ASPARTIC ACID CAUSING RELAXATION OF RETINAL ARTERIOLES THROUGH AN ADENOSINE RECEPTER DEPENDENT MECHANISM: A POSSIBLE MECHANISM OF VASODILATION IN DIABETIC RETINOPATHY

K. Holmgaard¹, C. Aalkjær², J.D.. Lambert², T. Bek<sup>1

1</sup>Aarhus University Hospital, Aarhus - Denmark
²University of Aarhus, Dept. of Physiology, Aarhus - Denmark

BACKGROUND. Disturbances in retinal perfusion due to impaired regulation of vascular tone are believed to be involved in the pathogenesis of diabetic retinopathy. These changes may be related to changes in the metabolism of glutamate and adenosine, but it remains to be elucidated in in vitro studies whether the relaxing actions of the two substances are separate or coupled.

METHODS. Porcine retinal arterioles with preserved perivascular retinal tissue were mounted in a myograph for isometric tone measurements. Changes in tone were induced by increasing concentrations of NMDA in the presence of blockers of adenosine receptors and ATP hydrolysis. Additionally, changes in tone were induced by increasing concentrations of adenosine in the presence of the NMDA receptor blocker, DL-APV. All concentration-response experiments were repeated after the perivascular tissue had been removed.

RESULTS. NMDA produced a concentration-dependent relaxing effect on retinal vessels with preserved perivascular retinal tissue (p<0.001) which disappeared after removal of this tissue. Blocking of the NMDA receptor, adenosine receptors, and hydrolysis of ATP significantly reduced the vasorelaxing effect of NMDA in the presence of perivascular retinal tissue (p<0.05 for all three comparisons). On the other hand, adeno-
sine produced a concentration-dependent relaxation that was not significantly affected by blocking the NMDA receptor with DL-APV, either on isolated arterioles (p=0.08) or on arterioles with preserved perivascular tissue (p=0.22).

CONCLUSIONS. The findings suggest that the vasorelaxing effect of NMDA in porcine retinal arterioles in vitro is mediated by hydrolysis of ATP to adenosine in the perivascular retinal tissue. This may be a potential mechanism for producing the vasodilation leading to hyperperfusion in diabetic retinopathy.

INTRACELLULAR CA2+ SPIKES IN RETINAL VASCULAR SMOOTH MUSCLE CELLS CAN BE MODIFIED TO POTENTIALLY IMPROVE MICROCIRCULATION IN RETINAL DISEASE

M.M. Misfeldt¹, C.A. Aalkjær², U.S. Simonsen³, T.B. Bek<sup>4

1</sup>Aarhus University Hospital, Aarhus - Denmark
²Aarhus University, Institute of Physiology and Biophysics, Aarhus - Denmark
³Aarhus University, Dept. of Pharmacology, Aarhus - Denmark
⁴Aarhus University Hospital, Dept. of Ophthalmology, Aarhus - Denmark

PURPOSE. Disturbances in the regulation of the retinal blood flow are involved in the pathophysiology of a variety of sight-threatening diseases, including diabetic retinopathy. Therapeutic intervention on these diseases on a rational basis requires a detailed knowledge of the mechanisms involved in the regulation of the tone in retinal resistance arterioles. This tone depends on recruitment of intracellular calcium in the vascular smooth muscle cells.

METHODS. Porcine retinal arterioles with a diameter of approximately 150 m were mounted in a wire myograph (DMT) and placed in a Zeiss LSM 5 Exciter confocal microscope allowing for simultaneous recording of vascular tone and calcium activity. The vessels were loaded with the calcium sensitive
fluorophore Oregon Green and were pre-contracted with the prostaglandin analogue U46619. The vascular tone and the concentration of free calcium was studied after application of Nifedipine 10-10M – 10-6M (blocking of L-type Ca2+-channels in the plasma membrane), and cyclo piazonic acid 10-10M – 10-6M and ryanodine 10-10M – 10-6M (Ca2+-channels in the sarcoplasmic reticulum).

RESULTS. Ryanodine did not affect the rate of spontaneous calcium spikes nor the vessel tone (p=0.8749 and p=0.98 one-way ANOVA n=6, respectively). Cyclo piazonic acid reduced the rate of intracellular calcium spikes significantly; EC50 2.5*10-8 [2.34*10-7; 3*10-9] (p< 0.0022, n = 5, repeated measures ANOVA). However, vessel tone was not affected (p=0.059 n=6, repeated measures ANOVA). Preliminary experiments showed that nifedipine induced an increase in the rate of spontaneous intracellular calcium in parallel with a marked decrease in vascular tone.

CONCLUSIONS . The recruitment of intracellular calcium in porcine vascular smooth muscle cells does not depend on ryanodine channels in the sarcoplasmic reticulum, but rather the IP3 channels. This feature is different from observations in other tissues. The intracellular calcium spikes can be modified using known pharmacologic drugs, including those used for the treatment of systemic cardiovascular disease in diabetic patients. This knowledge may serve as a way to intervene in diseases where the regulation of the blood flow is disturbed, such as diabetic retinopathy.

EFFECTS OF HIGH GLUCOSE AND THIAMINE ON THE BALANCE OF MATRIX METALLOPROTEINASES/TISSUE INHIBITORS IN PERICYTES AND ENDOTHELIAL CELLS

S. Tarallo, E. Beltramo, E. Berrone, P. Dentelli, M. Porta

University of Torino, Torino - Italy

PURPOSE/BACKGROUND. In diabetic retinopathy, pericyte survival is dependent, among other factors, on interactions with extracellular matrix (ECM) proteins, which are susceptible to degradation by matrix metalloproteinases (MMP). Elevated glucose concentrations can influence ECM synthesis and degradation, acting on the expression of MMP and their tissue inhibitors, TIMP. The authors reported previously on reduced adhesion of pericytes cultured on ECM produced by endothelium in high glucose and its correction by thiamine. In this article, the authors aimed at verifying the effects of thiamine and benfotiamine on MMP-2, MMP-9 and TIMP-1 expression and activity in human vascular cells in high glucose concentrations.

METHODS. Human retinal pericytes (HRP) and umbilical vein endothelial cells (HUVEC) were cultured in 5.6mmol/L or 28mmol/L glucose, with or without thiamine (T) or benfotiamine (BT). MMP-
2, MMP-9 and TIMP-1 mRNA expression was determined by RT-PCR and their activity by gelatin zymography; TIMP-1 concentrations were measured by ELISA.

RESULTS. In HRP, MMP-2 activity, though not expression, increased in high glucose (123.7 11.8% of G5.6, p<0.05) (QUERY: Please insert symbols as needed throughout abstract?) and was reduced by thiamine (94.5 11.7% of G5.6, p<0.05) and benfotiamine (78.4 26.9% of G5.6, p<0.05); TIMP-1 expression increased in high glucose plus thiamine (118.7 30.0% of G5.6, p<0.05) and benfotiamine (118.2 30.2% of
G5.6); MMP-9 was not expressed. In HUVEC, MMP-9 and MMP-2 expression did not change in high glucose, while their activity increased (MMP-2: 130.2 24.9% of G5.6, p<0.05; MMP-9: 120.0 19.1% of G5.6, p<0.05); thiamine and benfotiamine had no effects. TIMP-1 expression did not change in HUVEC. No effects on TIMP-1 concentration were found in either HRP or HUVEC.

CONCLUSIONS. High glucose may induce an imbalance in the MMP/TIMP regulation, leading to increased turnover of ECM. Thiamine and benfotiamine may correct the increase in MMP-2 activity due to high glucose in human pericytes, while increasing TIMP-1.

CONNECTIVE TISSUE GROWTH FACTOR (CTGF) INDUCES RETINAL CAPILLARY BASAL LAMINA THICKENING IN DIABETIC MICE

R.J. van Geest, E.J. Kuiper, C.J.F. van Noorden, R.O. Schlingemann AMC, Amsterdam - The Netherlands

BACKGROUND. Diabetic retinopathy (DR) is the leading cause of blindness in the western world. Vascular basal lamina (BL) thickening is a prominent feature of early DR. Experimental prevention of BL thickening reduced early retinal vascular changes due to diabetes. This indicates that BL thickening is not an epiphenomenon of diabetes but may be instrumental in DR and blindness. Modulation of BL thickening may have a preventive effect on DR. CTGF is a pro-fibrotic factor expressed in the retina under experimental diabetic conditions and in the diabetic patient. Therefore, the authors hypothesized that CTGF plays a role in early pathogenesis of DR by inducing BL thickening.

METHODS. This was tested in control and diabetic wild type mice (CTGF+/+) and mice lacking one functional allele (CTGF+/-). CTGF-/- mice die after birth and conditional CTGF-/- mice are not available yet. Diabetes was induced by streptozotocin treatment. At 16 weeks after induction of diabetes, blood glucose and CTGF levels, retinal mRNA levels of CTGF and TGF, and thickness of BL of retinal capillaries
were measured at the EM level using dedicated image analysis software. Blood glucose levels confirmed diabetes in the treated mice.

RESULTS. Blood CTGF levels were half the levels in CTGF+/- mice than in wild type mice. Retinal CTGF mRNA levels were 3-4-fold higher in diabetic CTGF+/+ mice than in control CTGF+/+ and CTGF+/- mice and diabetic CTGF+/- mice. TGF mRNA was elevated in diabetic retinas irrespective the CTGF genotype. BL thickening was significant in diabetic CTGF+/+ mice compared to control CTGF+/+ mice. Diabetes
did not induce significant BL thickening in CTGF+/- mice.

CONCLUSIONS. CTGF is necessary for diabetic retinal BL thickening and prevention of BL thickening may delay subsequent blindness due to DR.

DECREASE OF HYPOXIA-INDUCED NEOVASCULARIZATION IN ANGIOPOIETIN-2 DEFICIENCY BY REDUCED MMP ACTIVITY

F. Pfister¹, Y. Feng¹, Y. Wang¹, F. Vom Hagen¹, U. Deutsch<sup>2

1</sup>University Clinic Mannheim, Mannheim - Germany
²Theodor Kocher Institute, Bern - Switzerland

BACKGROUND. Proliferative diabetic retinopathy is characterized by the formation of pre-retinal neovascularization in response to intraretinal hypoxia. Previous data suggest that Angiopoietin-2 (Ang-2) plays a critical role in pericyte loss and vascular regression. Ang-2 expression is modified not only by glucose but also by hypoxia. Retinal overexpression of Ang-2 promotes intra- and pre-retinal neovascularization under hypoxia. Ang-2 stimulates matrix metalloprotease (MMP) expression in cultured tumor and endothelial cells. Furthermore, MMP expression in neovascularizations is inhibited by blocking the Ang-Tie system. However, the cellular expression pattern of Ang-2 in the vasculature under hypoxia
and the association of Ang-2 to MMP activity have not been elucidated. In this study, the authors investigated the response of Ang-2 deficient retinas (Ang2LacZ mouse) to hypoxia and its correlation to activity of MMPs in a model of oxygen-induced retinopathy (OIR).

METHODS. Pre-retinal neovascularizations were quantitated in vertical sections and intra-retinal angiogenesis was assessed by whole mount retinal immunofluorescence staining. MMP activity was detected by whole mount retinal in situ zymography.

RESULTS. Ang2LacZ retinas subjected to the OIR model showed significantly reduced neovascularization and increased avascular zone at postnatal day 17 compared to wild type retinas, while the avascular zone at p12, an initial time point for hypoxia-induced neovascularization, did not differ between the groups. In the OIR, Ang-2 was weakly detected in preretinal neovascularizations and venules, but strongly in arterioles and capillary sprouts towards the deep capillary layer in Ang2LacZ mice. Retinas of Ang2LacZ mice showed a substantially decreased activity of MMP in arterioles and capillary sprouts growing towards the deep capillary layer.

CONCLUSIONS. These data suggest that the response of retinal vasculature to hypoxia is modulated by Ang-2. Ang-2 is essentially required at the fronts of pathological neovascularization/vascular repair, and MMPs modify vascular invasion in cooperation with Ang-2.