Corneal Thickness In Eyes Research Articles

Preoperative central corneal thickness in eyes with pediatric cataract versus normal fellow eyes

To compare the preoperative central corneal thickness (CCT) in eyes with unilateral cataract with their normal fellow eyes in the pediatric population. A retrospective chart review was conducted using the STORM Kids cataract database. Eyes with traumatic cataract, previous surgery or therapeutic manipulation, or age >18 years were excluded. Only eyes with a normal fellow eye were included. The intraocular pressure, age at time of surgery, race, sex, and type of cataract were also extracted from the record. A total of 70 eyes with unilateral cataract and 70 fellow normal eyes met inclusion criteria. The mean age at the time of surgery was 3.35 years (range, 0.08-15.05). The mean preoperative CCT in the operated eyes was 577 ± 58 μm (range, 464-898 μm). The mean preoperative CCT in fellow eyes was 570 ± 35 μm (range, 485-643 μm). There was no statistically significant difference between the preoperative CCT in cataract eyes versus unaffected fellow eyes (P = 0.183). When stratified by age, the difference in the CCT between cataract and fellow eyes was greatest in the <1 year age group, but was not statistically significant (P = 0.236). The mean preoperative corneal diameter of operative eyes was 11.0 mm (range, 5.5-12.5 mm [n = 68]). The mean preoperative IOP was 15.1 mm Hg (n = 66). In our study cohort, there was no significant difference in mean preoperative CCT between unilateral pediatric cataract eyes and unaffected fellow eyes.

Corneal densitometry in bilateral keratoconus patients with unilateral corneal Vogt's striae: a contralateral eye study.

To investigate corneal densitometry and correlations with corneal morphological parameters in patients with bilateral keratoconus (KC) with unilateral Vogt's striae. This prospective contralateral study enrolled 112 patients (224 eyes) with evident KC characteristics (corneal topography with asymmetric bow-tie pattern, inferior steepening), and at least one KC sign (conical protrusion of the cornea at the apex, corneal stromal thinning, Fleischer ring, Vogt's striae) on slit-lamp examination. Corneal densitometry and morphological parameters were measured using Pentacam HR. The mean age was 23.93 ± 6.81years. Fifty-two (23.22%), 111 (49.55%), and 61 (27.23%) eyes were in mild, moderate, and severe groups, respectively. Corneal densitometry values of the anterior 0-2mm and 2-6mm, intermediate 0-2mm and 2-6mm, posterior 2-6mm, and total cornea 2-6mm were significantly higher in eyes with Vogt's striae (P < 0.05), whereas those of the anterior 6-10mm, posterior 0-2mm, and total cornea 6-10mm were significantly lower in eyes with Vogt's striae (P < 0.05). Anterior 0-2mm and total cornea 2-6mm corneal densitometry values were positively correlated with anterior K1 (A-K1), K2 (A-K2), Km (A-Km), Kmax (A-Kmax), anterior corneal elevation, and posterior corneal elevation (P < 0.05), and negatively correlated with central corneal thickness and thinnest corneal thickness in eyes with Vogt's striae (P < 0.05). A-K2, A-Km, and A-Kmax were significantly correlated with the densitometry values of the anterior 0-2mm and intermediate 0-2mm in eyes without Vogt's striae (P < 0.05). Vogt's striae mainly occur on the anterior and intermediate layers during KC progression.

A cross sectional study on evaluating the corneal endothelial cell density and central corneal thickness in eyes with primary glaucoma.

This study aims at evaluating glaucoma-induced damage to the corneal endothelium and the effect of central corneal thickness (CCT) on the intra-ocular pressure (IOP) measurement in patients newly diagnosed with primary glaucoma. It is a hospital-based cross-sectional study involving 60 newly diagnosed primary glaucoma patients >18 years. They underwent fundus examination, four-mirror gonioscopy, and perimetry for confirming the diagnosis. Evaluation and analysis of corneal endothelial cell density and CCT were performed. Chi square test was performed to find out the association between glaucoma, corneal endothelial cell density, and CCT. Evaluation of 60 patients revealed that by age distribution, the corneal endothelial cell density was lower in the 51-65 year age group and an age-related decrease in corneal endothelial cell density and CCT was found in newly diagnosed primary glaucoma patients. The mean CCT was 525 micrometers in patients with IOP between 20 to 40 mm Hg and 528 micrometers in patients with IOP between 41 to 60 mm Hg. The mean corneal endothelial cell density was 2361 cells/mm2 in primary open-angle glaucoma (POAG) and 2284 cells/mm2 in primary angle-closure glaucoma (PACG). The mean CCT was 525 micrometers in POAG and 528 micrometers in PACG. The corneal endothelial cell density was lower in patients with PACG when compared with POAG, and the average CCT showed no significant difference in POAG and PACG patients. However, CCT was increased in patients with a higher intra-ocular pressure. The corneal endothelial cell density was lower in patients with a high intra-ocular pressure.

Trans Palpebral Intraocular Pressure Measurement by Diaton Tonometer and Central Corneal Thickness in Eyes before and after Transepithelial Photorefractive Keratectomy of Saudi Patients.

The influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurement by Diaton is debatable. We present a correlation of CCT to transpalpebral IOP (tpIOP) and its determinants in patients undergoing transepithelial photorefractive keratectomy (TPRK) in Saudi Arabia. In this cross-sectional study held in 2022, the IOP of patients undergoing TPRK was measured by Diaton tonometer. The CCT was measured before and 1 week after refractive surgery. The correlation coefficient of CCT and IOP and its Pearson P value were estimated. The effects of gender, type of refractive error (RE), and corneal epithelial thickness (CET) on the correlation of IOP to CCT were reviewed. We studied 202 eyes in 101 patients (Male: Female, 47:53; age 25.7 ± 5.8 years). The tpIOP was 15.1 ± 2.8 mmHg before, 15.9 ± 2.8 mmHg 1 week after, and 15.7 ± 4.1 mmHg 1 month after TPRK. The CCT was significantly correlated with tpIOP before surgery (Pearson correlation 0.168, P = 0.017) and after tPRK (Pearson correlation 0.246, P < 0.001). Gender (P = 0.96), CET (P = 0.43), and type of RE (P = 0.99) were not significant determinants of correlation between CCT and tpIOP before TPRK. The correlation of tpIOP and CCT was not affected by gender (P = 0.07), CET (P = 0.39), and type of RE (P = 0.13). CCT should be considered before interpreting tpIOP measured by with Diaton. Diaton could be a useful tool to monitor IOP changes in young patients undergoing refractive surgery.

Preoperative central corneal thickness in eyes with pediatric cataract versus normal fellow eyes

In this study we compare the preoperative central corneal thickness (CCT) in eyes with unilateral cataract with their normal fellow eyes in the pediatric population.

Исследование клинико-статистических, анатомо-оптических и функциональных характеристик первичных кератэктазий у пациентов, проживающих в Дальневосточном федеральном округе России

Purpose. To study clinical, statistical, anatomical, optical and functional properties of primary keratoectasia (PKE) in patients living in Far Eastern Federal District of Russia. Material and methods. A retrospective analysis of medical outpatient cards of 481 patients with PKE who observed in the Khabarovsk branch of the S. Fyodorov Eye Microsurgery Federal State Institution. We studied the detectability of PKE over the years, their quantitative structure and staging, visual acuity, refraction, maximum keratometry-readings and minimum corneal thickness. Results. Keratoconus (KC) occurred in 445 (92.5%) patients, pellucid marginal degeneration (PMD) occurred in 36 (7.5%). Among patients with KC, it was observed in 309 (69.4%) men and 136 (30.6%) in women. PMD was diagnosed in 19 (53%) men and 17 (47%) women. In 386 (86.7%) people with KC, the lesion was bilateral. Among the remaining 59 patients with KC, 6 people (1.3%) had a one-sided process, and 53 (12%) patients had signs of subclinical KC in the second eye. Bilateral PMD was detected in 35 (97%) people, in one (3%) patient the disease was detected in one eye. At comparable average values of refraction and corneal thickness in eyes with PMD and KC 1st stage, astigmatism-at PMD were 2–2.5 times greater. Conclusion. Among patients with KC, 34.9% eyes have the 2nd stage of the disease, in which visual acuity are already sufficiently reduced, and 28.5% eyes have KC the 3rd and the 4th stage and can be classified as visually impaired. The revealed differences in ratio of functional and refractive indexes of eyes with KC and PMD necessitate wider study of their diagnostic features and results of treatment latter. Keywords: keratoectasia, keratoconus, pellucid marginal degeneration.

Comparative study of safety and efficacy of dispersive versus cohesive ophthalmic viscosurgical devices in cataract surgery after phacoemulsification

Background: To compare efficacy and safety of dispersive versus cohesive ophthalmic viscosurgical devices in cataract surgery after phacoemulsification to prevent endothelial cell loss. Material and Method: Total 40 consecutive patients of senile cataract with hard nucleus (grade 3/4) who attended AVBRH eye Opd were selected. 40 cases were randomly divided in two groups depending on the use of two different OVD's as – Group 1 Dispersive (20 cases): Hydroxypropyl methylcellulose (2 %), Group 2 Cohesive (20 cases): Sodium hyaluronate (1.4%). Preoperative examination and evaluation of BCVA, corneal thickness by pachymetry and endothelial cell count by specular microscope was done. ECCE with PCIOL implantation by phacoemulsification was performed by a single surgeon. Postoperative all the parameters were recorded on day 1, 1 week, 1 month and 3 months using the same methods and instruments. Results: In our study there was no significant change was seen preoperatively in age, visual acuity, intraocular pressure, and endothelial cell count among the two groups. Postoperatively rise in IOP was seen in both groups i.e. 30 % in group A and 10 % in group B, corneal endothelial cell loss was seen in both groups after performing phacoemulsification, there was no significant difference in the change in cornea thickness in eyes among two groups (P=0.20). Conclusion: Our study shows no significant difference in endothelial cell count and corneal thickness in eyes between two groups.

Effect of topical steroid instillation on central corneal thickness in eyes with bullous keratopathy.

To examine the effects of topical steroid instillation on central corneal thickness in eyes with bullous keratopathy (BK). Retrospective case series METHODS: Consecutive patients with BK who did not wish to receive corneal transplantation and were treated with 0.1% betamethasone eyedrops were included. Patients with BK treated with 5% sodium chloride (hypertonic saline) eyedrops served as controls. Central corneal thickness (CCT),best-corrected visual acuity (BCVA), intraocular pressure (IOP), BK etiology,and clinical courses from medical records were retrospectively reviewed. We compared the two groups for differences in CCT, BCVA and IOP before treatment and 2 weeks, 1 month, and 3 months after treatment. Eighteen eyes of 18 patients who were treated with betamethasone and 18 eyes of 18 patients who were treated with hypertonic saline were included. There was no significant difference in CCT between the two groups before treatment. The reduction of CCT in the betamethasone group was significantly larger than in the hypertonic saline group at 2 weeks (p = 0.002), 1 month (p = 0.02), and 3 months (p = 0.001) after treatment. Complications such as infectious keratitis and IOP rise did not occur during the observation period. Topical steroid instillation reduced central corneal thickness in eyes with BK.

Association Between Lamina Cribrosa Defects and Progressive Retinal Nerve Fiber Layer Loss in Glaucoma

Certain features of the lamina cribrosa may be associated with increased risk of glaucoma progression. To compare the rates of retinal nerve fiber layer (RNFL) thinning in patients with open-angle glaucoma with or without lamina cribrosa (LC) defects and to evaluate factors associated with the rate of glaucoma progression in eyes with LC defects. This longitudinal cohort study designed in September 2017 and conducted at a tertiary glaucoma center in California included 51 eyes of 43 patients with LC defects and 83 eyes of 68 patients without LC defects followed up for a mean (SD) of 3.5 (0.8) years from April 2012 to May 2017. Focal LC defects were detected using swept-source optical coherence tomographic images. All participants underwent visual field testing and spectral-domain optical coherence tomography for RNFL thickness measurements every 6 months. Univariate and multivariable random-effects models were used to compare the rate of local and global RNFL loss. The mean (95% CI) age at baseline for individuals with LC defects was 69.5 (65.4 to 73.6) years, and for those without LC defects, it was 69.6 (67.2-72.0) years; 18 individuals (41%) with LC defects and 35 individuals (51%) without LC defects were men; 6 individuals (14%) with LC defects and 17 individuals (25%) without were African American. The mean (95% CI) rate of global RNFL loss in eyes with LC defects was 2-fold faster than that in eyes without LC defects (-0.91 [-1.20 to -0.62] vs -0.48 [-0.65 to -0.31] μm/y; difference, -0.43 [-0.76 to -0.09] μm/y; P = .01). The rate of RNFL thinning was faster in the LC defect sectors than that in the unaffected sectors (difference, -0.90 [95% CI, -1.68 to -0.12] μm/y, P = .02). Thinner corneal thickness was the only factor that was associated with a faster rate of RNFL loss in eyes with LC defects (β2 = -0.09 [95% CI, -0.14 to -0.04], P = .001). No association was found between mean intraocular pressure during follow-up and the mean rate of RNFL thinning in eyes with LC defects (β2, -0.05 [95% CI, -0.17 to 0.06], P = .36). These data suggest that LC defects are an independent risk factor for RNFL thinning and that glaucoma progression may correspond topographically to the LC defect location. Thinner corneal thickness in eyes with LC defects was associated with faster further glaucoma progression. In the management of open-angle glaucoma, LC findings may inform the likelihood and rate of glaucoma progression.

Comparing effect of clear corneal incision and sclera tunnel incision in phacoemulsification on central corneal thickness

Aim: To compare the effect of clear corneal incision and sclera tunnel incision on central corneal thickness in eyes undergoing phacoemulsification. Setting: Department of ophthalmology, Government Medical College Haldwani, Nainital, Uttarakhand. Materials and Methods: This prospective study included 68 eyes with senile cataract from grade 1 to 3 which underwent phacoemulsification during May 2015 to October 2015 through clear corneal incision or through sclera tunnel incision. Patients were randomly assigned in group 1 with clear corneal incision and group 2 with sclera tunnel incision. All the surgeries were performed by single surgeon using same technique. Postoperatively central corneal thickness were measured with optical non-contact biometry in both the groups on 2nd post-op day, at 1-2 weeks, 6-8 weeks and at 3 months and compared. Results: Mean increase in CCT on 2nd postoperative day was 82µm and 62 µm in Group I and Group II respectively. At 2 weeks it was 51 µm and 23 µm, at 6 weeks it was 30 u µm and 5 µm, at 3 months 4 µm and 5 µm more than the baseline values. Conclusion: This study revealed that increased CCT as caused by corneal oedema occurring in immediate postoperative period was more in Group I as compared to Group II. The values returned to normal range in 3 months and 2 months in Group I and Group II respectively. Key words: Clear corneal incision, Central corneal thickness, Scleral tunnel incision

Central corneal thickness in eyes with pseudoexfoliation syndrome in Kashmir Valley - a hospital based study

Introduction: Pseudoexfoliation syndrome (PEX) is characterized by the production and accumulation of extracellular granular fibrillar material in many ocular tissues. Pseudoexfoliation has been closely associated with glaucoma and raised intraocular pressure (IOP) is the most important known risk factor for glaucoma. Central corneal thickness (CCT) may affect the accuracy of IOP measurements. Thus, it is possible to underestimate/overestimate the IOP reading in the PEX syndrome and overlook an early glaucomatous damage. The aim of our study was to determine the central corneal thickness (CCT) in eyes with pseudoexfoliation (PEX). Methods: Total 2076 eyes (of 1224 patients) with pseudoexfoliation on clinical examination were enrolled in this prospective clinical study and CCT was measured in each eye using specular microscopy. Results: Mean CCT (????m) in eyes with Pseudoexfoliation was 525.43 ± 34.27. CCT in eyes with Hypertensive PEX (513.2 ± 27.8) and PEX Glaucoma (509.22 ± 29.76) was significantly thinner than in eyes with Normotensive PEX (528.17± 30.33) (P = 0.001, P = 0.0001, respectively). There was no significant difference in CCT between the fellow eyes in cases of unilateral pseudoexfoliation (P = 0.54). Conclusion: Mean central corneal thickness (CCT) in eyes with pseudoexfoliation is 525.4 µm and CCT is significantly thinner in Hypertensive PEX as well as Glaucomatous PEX eyes than Normotensive PEX eyes.

Corneal thickness of eyes with unilateral age-related macular degeneration.

To compare the central corneal thicknesses (CCT), peripheral corneal thicknesses, and corneal volumes (CV) of the 2 eyes of patients with unilateral age-related macular degeneration (AMD). Twenty patients who were diagnosed with unilateral AMD were included in this prospective study for the purpose of making comparison between the diseased and healthy eyes. Optical coherence tomography and fundus fluorescein angiography imaging were applied to all patients in order to confirm and reveal the presence of unilateral AMD. Then, the measurements of CCT, peripheral corneal thickness measured 4 mm distant from the center of the cornea (4 mm CT), and CV of each eye of these patients were obtained through the rotating Scheimpflug corneal topographer. Wilcoxon signed-rank test did not demonstrate a statistically significant difference between the 2 eyes of patients with unilateral AMD when we compared the CCT and CV of diseased and healthy eyes (p>0.05). However, 4 mm CT of the diseased eyes of these patients were statistically significantly thicker than the healthy eyes (p<0.05). The significant difference in terms of 4 mm CT between the diseased and healthy eyes of patients with unilateral AMD may demonstrate the possible effect of peripheral corneal thickness on the development of AMD.

This issue of ACTA, printed and electronic

This issue of <i><scp>ACTA</scp></i>, printed and electronic

Corneal endothelial cells 6–7 years following cataract surgery in patients with pseudoexfoliation syndrome

To assess the condition of the corneal endothelium an extended period after cataract surgery in eyes with and without pseudoexfoliation syndrome (PES). Forty-six patients with PES who underwent cataract surgery in the Eye Department, Oslo University Hospital, in 2001 and 2002 were enrolled and compared to 101 matched controls without PES who had surgery in the same period. They were re-examined 6-7 years following surgery with measurements taken of corneal endothelial cell density (ECD), pleomorphism, polymegathism and corneal thickness. Mean ECD was 2024 ± 371 cells/mm(2) in eyes with PES and 2144 ± 365 cells/mm(2) in eyes without PES. The difference was not statistically significant. No significant difference in polymegathism and pleomorphism was noted. Mean corneal thickness was 543 and 547 μm in eyes with and without PES, respectively (not statistically significant). The presence of glaucoma in pseudoexfoliative eyes was not associated with endothelial cell changes. Six to 7 years following cataract surgery, no statistically significant differences were established in ECD, pleomorphism, polymegathism and corneal thickness in eyes with and without PES. No clinical signs of corneal decompensation were noted amongst the participants.

Corneal curvature and central corneal thickness in eyes with pseudoexfoliation syndrome

Background: Previous studies have reported different central corneal thickness (CCT) values in eyes with pseudoexfoliation syndrome (PXS). There has been no report about corneal curvature (CC) in PXS eyes. The aim of this study was to investigate the CCT together with the CC in PXS eyes with and without glaucoma. Methods: The CC (simulated keratometry 1 [SimK1], SimK2, and mean K) and CCT were prospectively studied by rotating a Scheimpflug camera in 72 PXS eyes and comparing them with 65 normal eyes. Results: In all PXS eyes, the mean K was significantly steeper than in control eyes (44.1 [SD 1.5] diopters (D) vs. 43.2 [SD 2.0] D, p = 0.04). When PXS eyes were subcategorized, the mean K was significantly steeper in both normotensive PXS eyes (44.6 [SD 1.6] D) and pseudoexfoliation glaucoma (PEXG) eyes (44.0 [SD 1.2] D) than normal eyes (43.2 [SD 2.0] D) ( p = 0.001 and 0.02, respectively). In all PXS eyes, the mean CCT (546.4 [SD 39.6] μm) was not significantly different than the control eyes (542.9 [SD 32.2] μm) ( p = 0.56). When PXS eyes were subcategorized, however, the CCT was significantly thinner in normotensive PXS eyes and significantly thicker in PEXG eyes. Interpretation: It appears that PEXG eyes have a significantly steeper CC and higher CCT than normal eyes. This could be of clinical significance because overestimation of true intraocular pressure may then occur in these eyes.

Corneal Injury by Anti-Misting Agent in Swim Goggles

To report a case of corneal injury by swim goggle anti-misting agent. Case report. A 47-year-old man presented with ocular injury caused by swim goggle anti-misting agent. Two weeks previously, the patient felt sudden ocular pain and grit after pool water flooded his goggles while swimming. Before the patient's swim, a copious amount of anti-misting agent was sprayed inside his goggles. On examination, severe corneal epithelial defect and stroma edema of the right eye were noted. Best-corrected visual acuity (BCVA) was 20/40. Right eye corneal thickness was 625 microm. Topical corticosteroids, antibiotic eye drops, and oral tetracycline were started. After 1 week of treatment, the epithelial defect of his right cornea improved slightly. Stromal edema decreased mildly. Epithelial defect persisted at 1 month follow-up. Right eye BCVA remained 20/40. Three months after treatment, the right eye epithelial defect healed completely. Mild diffuse superficial stromal opacity was noted. BCVA improved to 20/20. At 1-year follow-up, right eye corneal thickness was 547 microm, which was thinner than the left eye. Right eye corneal endothelial cell density measured approximately 1500 cells/mm2, which was less than the left eye at 2300 cells/mm2. The faint, diffuse stromal opacity disappeared; however, white subepithelial plaques were noted in the cornea centers. After 1 month of treatment with topical corticosteroids, the plaques subsided completely. The corneas remained clear at 2-year follow-up. Anti-misting agent can cause severe corneal injuries, including persistent epithelial defects, stromal edema and opacity, endothelial cell loss, and subepithelial plaque.

Corneal thickness in eyes following pars plana lensectomy for congenital cataracts.

To evaluate the corneal thickness following pars plana lensectomy for congenital cataracts. The corneal thickness was measured in 24 eyes of 24 patients with congenital cataracts who had undergone pars plana lensectomy at a mean age of 24 +/- 32 (SD) months. The mean age at the time of our evaluation was 15 +/- 3 years. These measurements were compared with those in 15 eyes of an age-matched group of 15 normal volunteers. The central corneal thickness and endothelium were evaluated in both groups. The mean corneal thickness of the cataract-extracted eyes (592 +/- 47 micro m) was significantly greater than that of the controls (529 +/- 43 micro m; P < 0.001). There was no significant difference in the corneal endothelial cell count between cataract-extracted eyes (3420 +/- 715/mm(2)) and the controls (3182 +/- 358/mm(2); P = 0.49). However, there were significant differences in the frequency of hexagonally shaped endothelial cells (63% +/- 8.4%, cataract-extracted eyes; 70% +/- 7.7%, controls; P < 0.01), and in the coefficient of variation in the endothelial cell size (33 +/- 6.0, cataract-extracted eyes; 26 +/- 4.8, controls; P< 0.01). The central cornea of congenital cataract-extracted eyes was significantly thicker than that of controls.

Density of corneal endothelial cells and corneal thickness in eyes of euthanatized horses.

To determine density of corneal endothelial cells and corneal thickness in eyes of euthanatized horses. 52 normal eyes from 26 horses. Eyes were enucleated after horses were euthanatized. Eyes were examined to determine that they did not have visible ocular defects. Noncontact specular microscopy was used to determine density of corneal endothelial cells. Corneal thickness was measured, using ultrasonic pachymetry or specular microscopy. Mean density of corneal endothelial cells was 3,155 cells/mm2. Cell density decreased with age, but sex did not affect cell density. Values did not differ significantly between right and left eyes from the same horse. Cell density of the ventral quadrant was significantly less than cell density of the medial and temporal quadrants. Mean corneal thickness was 893 microm. Sex or age did not affect corneal thickness. Dorsal and ventral quadrants were significantly thicker than the medial and temporal quadrants and central portion of the cornea. We did not detect a correlation between corneal thickness and density of endothelial cells in normal eyes of horses. Density of corneal endothelial cells decreases with age, but corneal thickness is not affected by age or sex in normal eyes of horses. The technique described here may be useful for determining density of endothelial cells in the cornea of enucleated eyes. This is clinically relevant for analyzing corneal donor tissue prior to harvest and use for corneal transplantation.

Corneal thickness in eyes with diabetic and nondiabetic neovascularisation.

The corneal thickness was measured in 20 patients with ocular neovascularisation of diabetic and nondiabetic aetiology. Mean corneal thickness (+/- SD) was 0.561 mm (+/- 0.027) and 0.499 mm (+/- 0.029) in the diabetic (n = 11) and the nondiabetic groups (n = 9), respectively (2p less than 0.001). The increased corneal thickness in the diabetic group is comparable to that previously reported in diabetics with proliferative retinopathy. These results indicate that the increased corneal thickness found in diabetics is peculiar to the diabetic eye and not secondary to the process of ocular neovascularisation as such.