Search

To determine the optimal area of retinal photocoagulation required for suppressing active neovascularisation (NVI) associated with diabetic retinopathy. We studied 1 eye each of 4 patients in whom active NVI was ophthalmoscopically shown to have been suppressed by additional photocoagulation. These patients initially underwent pan-retinal photocoagulation for diabetic retinopathy at another hospital, but NVI developed subsequently. We compared the areas of photocoagulation before and after additional photocoagulation and compared the area of retinal photocoagulation. The photocoagulated areas before and after additional photocoagulation in the four eyes were 20.7 and 45.2, 36.6 and 56.3, 30.4 and 67.4, and 11.7 and 53.4 %, respectively. The area of retinal photocoagulation required to suppress active NVI is calculated to be ~50 %.

Purpose: To determine the 1-year and 2-year likelihood of vitrectomy in diabetic patients undergoing initial pan retinal photocoagulation (PRP)., Methods: Diabetic eyes receiving initial PRP for proliferative diabetic retinopathy (PDR) were analyzed to determine their risk for vitrectomy based on clinical findings., Results: In total, 374 eyes of 272 patients were analyzed. The percentage of eyes undergoing vitrectomy 1 year and 2 years following initial PRP was 19.1% and 26.2%, respectively. Of the eyes in Group 1 (PDR alone), Group 2 (PDR and vitreous hemorrhage), and Group 3 (PDR and iris neovascularization, vitreous hemorrhage with traction or fibrosis, or fibrosis alone), the percentage receiving pars plana vitrectomy at 1 year and 2 years was 9.73% (18/185) and 15.7% (29/185), 26.9% (43/160) and 34.4% (55/160), and 37.9% (11/29) and 48.3% (14/29), respectively. Eyes in Group 2 had 2.78 times greater likelihood (P < 0.0001) and eyes in Group 3 had 3.54 times higher likelihood (P < 0.0001) of requiring pars plana vitrectomy within 2 years than those with PDR alone., Conclusion: Eyes receiving PRP for PDR with associated hemorrhage or traction were more likely to undergo pars plana vitrectomy within 1 year and 2 years following initial PRP compared with eyes with only PDR, providing important prognostic information for PRP-naive patients.

Purpose: To evaluate the results of surgery with pars plana vitrectomy (PPV), endodiathermy of sclerotomy site fibrovascularization and adjuvant photocoagulation of the peripheral retina to the pars plana as treatment of recurrent vitreous hemorrhage secondary to PPV for proliferative diabetic retinopathy (PDR)., Methods: Tertiary care center, Barraquer Center of Ophthalmology, Barcelona, Spain. Prospective interventional study of 14 eyes of 14 consecutive patients aged 20 years to 47 years with recurrent vitreous hemorrhage because of sclerotomy site neovascularization secondary to PPV for PDR. All patients were treated by cataract, or transparent lens, extraction with intraocular lens implantation plus 20-gauge PPV of the vitreous base, including incarcerated vitreous of the sclerotomy site, together with endodiathermy of sclerotomy site fibrovascular tissue and adjuvant photocoagulation to the pars plana. Preoperative evaluation was performed by 20-MHz, high-resolution, anterior-segment ultrasonography of the neovascularized sclerotomy sites, pre- and postoperative visual acuity (logarithm of the minimum angle of resolution), and postoperative rebleeding rates., Results: Recurrent vitreous hemorrhage appeared 8 ± 4 months after the initial PPV for PDR. Ten (71%) patients had isolated vascularization of a single sclerotomy site and 4 (29%) had vascularization of 2 sclerotomy sites. Nine of the 18 vascularized sites (50%) corresponded to optical fiber sclerotomies, 7 (39%) to vitreotome, and 2 (11%) to infusion sclerotomies. All the neovascularized sclerotomies presented sentinel vessels in the anterior segment. No patient showed postoperative recurrent vitreous hemorrhage during follow-up of 23 ± 10 months; all showed improved visual acuity, from initial 2.23 (±1.13 standard deviation) to final 0.23 (±0.09 standard deviation)., Conclusion: According to our study, the technique of choice for the treatment of recurrent vitreous hemorrhage secondary to PPV for PDR is endodiathermy of sclerotomy site fibrovascularization and adjuvant photocoagulation of the peripheral retina to the pars plana. This technique treats the etiology of the problem, improves final best-corrected visual acuity, and, most importantly, helps prevent recurrent bleeding.

Aim: To briefly review and discuss the literature on why patients still require surgery for the late complications of proliferative diabetic retinopathy (PDR)., Methods: Literature review., Results: The reasons for incomplete coverage of screening and screening failures can be divided into non-modifiable and potentially modifiable risk factors. The non-modifiable group includes duration of diabetes, age, genetic predisposition, ethnic differences, and the various reasons for vitrectomy when optimum laser treatment has been applied at the appropriate stage of the disease process. The potentially modifiable group includes glycaemic control, blood pressure control, lipid control, and cessation of smoking in type 1 diabetes. Other potentially modifiable factors include adequacy of screening, including reaching the regular non-attender, and attempting to modify the psychological factors that lead to late presentations including depression and eating disorders. Other potentially modifiable risk factors are optimising laser treatments and the potential use of anti-VEGF therapy to prevent vitrectomy in iris neovascularisation and neovascular glaucoma., Conclusion: Surgery for the late complications of PDR continues to be required even in some patients who have received optimal medical care and optimal laser treatment. There are certain modifiable risk factors that could be altered and further research is needed in specific fields, particularly with regard to the adequacy of laser treatments, the use of anti-VEGF agents in iris neovascularisation, and in the role of psychological support in reducing the type of late complications leading to surgery for PDR.

Purpose: Neovascular glaucoma is a frequent complication of vitrectomy performed to treat proliferative diabetic retinopathy (PDR). We assessed the level of vascular endothelial growth factor (VEGF) in the vitreous fluid obtained during vitrectomy and at postoperative fluid-air exchange., Methods: We measured VEGF levels in vitreous samples from 17 eyes of 15 patients with PDR during vitrectomy and fluid samples obtained during fluid-air exchange 5 to 36 days postoperatively. Six of the 17 eyes had iris neovascularization after vitrectomy. Vascular endothelial growth factor levels also were measured in the vitreous fluid obtained from 8 eyes with a macular hole during vitrectomy and postoperative fluid-air exchange. We measured the plasma VEGF levels in all patients., Results: The mean VEGF levels in 17 eyes with PDR were 1162.3+/-173.2 pg/ml in the vitreous samples and 1180.4+/-182.8 pg/ml in the postoperative fluid samples. The mean plasma VEGF level was 116.1+/-10.2 pg/ml in eyes with PDR, and the mean plasma VEGF level was 118.5+/-15.2 pg/ml in patients with a macular hole. The mean VEGF levels were 96.9+/-11.5 pg/ml in the vitreous samples and 73.9+/-12.3 pg/ml in the fluid samples in eyes with a macular hole., Conclusions: A high VEGF level was maintained in the vitreous cavity after vitrectomy for PDR. The VEGF level in eyes with PDR was 10 times higher than that in the plasma. The results suggest that there is persistent secretion of VEGF into the vitreous cavity even after vitrectomy for PDR.

Diabetic retinopathy remains one of the major causes of acquired blindness in developed nations. This is true despite the development of laser treatment, which can prevent blindness in the majority of those who develop macular oedema (ME) or proliferative diabetic retinopathy (PDR). ME is manifest by retinal vascular leakage and thickening of the retina. The hallmark of PDR is neovascularisation (NV)--abnormal angiogenesis that may ultimately cause severe vitreous cavity bleeding and/or retinal detachment. Pharmacologic therapy aimed specifically at preventing vascular leakage and NV would be a welcome addition to the armamentarium. PDR and ME could be prevented by improved metabolic control or by pharmacologically blunting the biochemical consequences of hyperglycaemia (e.g., with aldose reductase inhibitors, inhibitors of non-enzymatic glycation or by protein kinase C [PKC] inhibition). The angiogenesis in PDR could be treated via growth factor (e.g., vascular endothelial growth factor [VEGF], insulin like growth factor-1 [IGF-1]) blockade, integrin (e.g., alpha-v beta-3) blockade, extracellular matrix alteration (e.g., with steroid compounds) or interference with intracellular signal transduction pathways (e.g., PKC and mitogen activated protein kinase [MAPK] pathway proteins). Some of these antiangiogenic agents may also prove useful for treating or preventing ME. Numerous potentially useful antiangiogenic compounds are in development; two drugs are presently in clinical trials for treatment of the preproliferative stage of PDR, while two are in clinical trials for treatment of ME.

Aim: To investigate the prevalence and the outcome of management of fibrovascular ingrowth (FVI) in eyes undergoing vitreous cavity washout (VCWO) following vitrectomy for diabetic retinopathy., Method: FVI was searched for at VCWO for in 19 consecutive eyes with proliferative diabetic retinopathy undergoing vitreous surgery for recurrent vitreous cavity haemorrhage over an 18 month period; the findings were correlated with the presence or absence of associated sclerotomy vessels externally. Eyes with richly vascularised ingrowths from the pars plana entry sites, as well as eyes with less extensive ingrowths but extensive retinal ablation applied at previous surgery for recurrent haemorrhage, underwent lensectomy and ciliary membrane dissection in addition to extensive retinopexy (n=6). Less severe cases received peripheral laser and cryotherapy only. The outcome of repeat surgery was studied prospectively in the 11 eyes with FVI., Results: 11 of the 19 eyes had a definite FVI from one or more of the original pars plana sclerotomies. In six of 11 eyes with FVI a large external episcleral vessel was present entering the original sclerotomy sites at which ingrowth was found peroperatively, but such sclerotomy vessels were also present in three of eight eyes with no FVI detected on the internal aspect of the sclerotomy. Two patients were lost to follow up and the remaining nine patients with FVI had no further vitreous cavity haemorrhage during initial follow up of 2-5 months., Conclusions: FVI has until now been considered an infrequent occurrence following vitrectomy for diabetic retinopathy. These findings would suggest that it is not uncommon and careful examination of the sclerotomy sites should be undertaken in all cases with recurrent haemorrhage and if FVI is found this should be treated appropriately.

Purpose: To study the fluorescein angiographic appearance of the extreme peripheral retina in patients with proliferative diabetic retinopathy with rubeosis iridis., Methods: Using a modified endoscope, fluorescein angiography was performed prospectively during pars plana vitrectomy on 14 eyes of 12 patients with proliferative diabetic retinopathy who had or developed postoperative rubeosis. These findings were compared with those obtained from 41 eyes of 35 patients without rubeosis., Results: A fibrovascular ridge was observed at the ora serrata in 11 of 12 eyes (92%) with rubeosis but in only 15 of 35 (43%) eyes without rubeosis. Seven of 12 (58%) eyes with rubeosis showed the continuous type of fibrovascular ridge, whereas only 5 of 35 (14%) eyes without rubeosis showed the continuous type. A broom-shaped continuous fibrovascular ridge was observed only in eyes with rubeosis., Conclusions: Many eyes with proliferative diabetic retinopathy showed unusual findings in the extreme retinal periphery, which were more frequent in the eyes with rubeosis iridis. Fluorescein angiography of this region may provide valuable information for possible anterior neovascularization.

Objective: The purpose of the study is to determine whether the 810-nm diode wavelength using a rectangular waveform is clinically effective in the treatment of choroidal neovascularization from age-related macular degeneration and to determine whether macular edema secondary to branch vein occlusion or diabetic retinopathy can be effectively treated with this laser using the micropulse waveform., Design: Review of consecutive nonrandomized patients whose eyes were treated with the diode laser over a 30-month period., Participants: Fifty-three patients with an initial presentation of choroidal neovascularization located subfoveally (77%), extrafoveally (17%), and juxtafoveally (6%); 14 patients with macular edema from a branch vein occlusion; and 59 patients with diabetic macular edema, 40 of which were treated for the first time., Intervention: Ablative rectangular wave laser photocoagulation was applied to the choroidal neovascular membranes and very light threshold treatment was applied in a macular grid to treat retinal edema. Microaneurysms were not targeted., Main Outcome Measures: Anatomic resolution of macular edema or choroidal neovascularization and visual acuity., Results: Sixty percent of eyes treated for choroidal neovascularization had no persistence or recurrence at 6 months, and 72% achieved visual stabilization. In 8% of eyes, some localized bleeding occurred during photocoagulation. Clinical resolution of macular edema from branch vein occlusion occurred by 6 months in 92% of eyes, and 77% had stabilization of visual acuity. At 6 months, 76% of newly treated patients with diabetic macular edema and 67% of previously treated patients had clinical resolution of their edema. Vision was improved or stabilized in 91% and 73% of newly treated and retreated patients at 6 months, respectively., Conclusions: The micropulsed 810-nm diode laser is clinically effective in the treatment of macular edema from venous occlusion and diabetic retinopathy, and the rectangular (normal) mode diode laser can be used in many eyes with choroidal neovascularization.

Effective mechanisms of laser photocoagulation for neovascularization in diabetic retinopathy were investigated in regard to change in oxygen pressure in the retina and vitreous and cytokines related to ischemia. The mechanism of laser photocoagulation is suggested to be as follows. 1. Destruction of the outer retina, especially of photoreceptors that have high oxygen consumption decreases metabolic function of the outer retina and its oxygen consumption. 2. The destruction allows increase of oxygen diffusion from choroidal vessels to inner retina, which improves the metabolic function by equilibrating oxygen demand and supply in the inner retina. (3) Production and secretion of neovascular factors such as vascular endothelial growth factor (VEGF) is decreased by the improvement of hypoxia. 4. The neovascularization is decreased by the synergistic effect between the neovascular factors and suppressors such an VEGF, fibroblast growth factor (FGF), and transforming growth factor-beta (TGF-beta). The improvement of the retinal ischemia and the decrease of cytokines are implicated in the regression of neovascularization by the laser photocoagulation for diabetic retinopathy.

The aim of this study was to compare the efficacy of various dye laser wavelengths in different forms of retinopathies. The study material consisted of 292 eyes of 210 diabetic retinopathy patients treated with dye laser photocoagulation between 1990 and 1992. All the patients were followed for at least 6 months after photocoagulation. Non-proliferative changes (maculopathy and/or preproliferative retinopathy) were present in 135 (46.3%) and proliferative retinopathy in 157 (53.7%) of the eyes undergoing photocoagulation. Of the 157 eyes with proliferative retinopathy, 60 (20.5%) had disc neovascularization, 71 (24.3%) had retinal neovascularization and 26 (8.9%) had retinitis proliferans. Yellow dye laser (580 nm) was applied in 92 (31.5%) eyes, red dye laser (630 nm) in 120 (41.1%) eyes and both yellow and red dye lasers in 80 (27.4%) eyes. There was no significant difference between the different wavelength groups with regard to visual acuity changes before and after treatment (p < 0.01). Overall, the visual acuity was maintained in 56.2% and improved in 25.0% of the eyes. After panretinal photocoagulation, disc neovascularization regressed partially or completely in 47 (78.3%) of the eyes. There was no significant difference among the various laser wavelengths with regard to treatment efficacy judged by the disappearance or regression of disc neovascularization (p < 0.01). All retinal neovascularizations regressed completely with laser treatment, but in 7 eyes (9.9%) new retinal neovascularizations in previously untreated areas developed. Dye laser has not resulted in any complications. It requires lower power settings compared to argon laser and thus facilitates photocoagulation. Another advantage of dye laser is the ability to use yellow and red wavelengths sequentially.

Panretinal cryopexy was used for the treatment of 15 eyes with neovascularization of the anterior segment, treated with panretinal photocoagulation in the past. The eyes were classified preoperatively according to grade of neovascularization of the iris and anterior chamber angle using Weiss' and Gold's device system. Four eyes had rubeosis iridis with normal intraocular pressure and 11 had neovascular glaucoma. Rubeosis was secondary to proliferative diabetic retinopathy and/or central retinal vein occlusion. Nine eyes with grade 0, I and II neovascularization showed regression of neovascularization and controlled intraocular pressure. Six eyes with grade IV showed regression of neovascularization but uncontrolled intraocular pressure. All those eyes presented extensive peripheral anterior synechias.

The clinical course in 50 eyes was analysed after pars plana vitrectomy for progressive diabetic fibrovascular proliferations. Patients were assigned to pars plana vitrectomy if progression of proliferations occurred despite a photocoagulation treatment with a mean number of 3500 burns and additional peripheral cryoablation. All cases had visual impairment because of fibrovascular tissue covering the macula without detachment of the macula. Flat proliferations were present in all eyes without retinal elevation, vitreous detachment, or vitreous haemorrhage. The follow up intervals ranged from 13 months to 39 months (mean interval 24 months). Twelve months postoperatively, 36 eyes (72%) showed improved visual acuity, five eyes (10%) were worse, and nine eyes (18%) were unchanged. Thirty two eyes (64%) achieved a final visual acuity of 0.2 or better, and 45 eyes (90%) gained 0.05 or better. In only two eyes could reproliferation be observed. The postoperative course indicates that pars plana vitrectomy for diabetic fibrovascular proliferations covering the macula can preserve socially useful visual acuity of at least 0.05 in most cases.

The study enrolled 59 eyes with rubeosis iridis and proliferative diabetic retinopathy. The efficacies of two types of panretinal photocoagulation ('full' and 'mild' scatter) on the course of diabetic rubeosis iridis were compared. The mean posttreatment follow-up period was 22 +/- 4.8 months. After application of full-scatter photocoagulation (1,200-1,600 spots) in 27 eyes, rubeosis iridis regressed in 70.4% cases, remained unchanged in 14.8% and deteriorated in 14.8%. After mild-scatter photo-coagulation (400-650 spots) in 32 treated eyes, rubeosis iridis regressed in 37.5% cases, 34.4% was unchanged, while deterioration was found in 28.1%. A better therapeutic effect of panretinal photocoagulation in regression of diabetic rubeosis iridis was obtained, if the total dose of the applied laser spots was higher.

Acute onset or exacerbation of rubeosis iridis associated with peripheral retinal detachment after vitrectomy represents a rare but serious complication of advanced diabetic retinopathy that indicates a poor prognosis. The clinical features, surgical procedures, and anatomical and functional results for a series of 13 eyes presenting with this complication are reported. In addition to rubeosis iridis and peripheral retinal detachment, anterior hyaloidal fibrovascular proliferation (APH) was also present in 10 eyes. All eyes had undergone one or more previous vitrectomies for diabetic complications such as nonclearing vitreous hemorrhage and traction retinal detachment. Treatment modalities for iris neovascularization and peripheral retinal detachment included reattachment procedures with an encircling band, peripheral membrane peeling, and, if necessary, peripheral retinectomy. Peripheral coagulation therapy was performed in all eyes. Eight eyes received an intraocular silicone-oil tamponade. Early results (4 weeks post-surgery) showed regression or stabilization of rubeosis iridis in all eyes. Later results (mean, 9 months post-surgery) revealed nine eyes with stabilized anterior ocular neovascularization and reattachment of the retina. Four eyes were anatomic failures due to recurrent rubeosis iridis/AHP or traction retinal detachment, and three of them also developed ocular hypotony. None of the eyes has thus far been lost as a result of neovascular glaucoma or painful phthisis. Ambulatory vision was retained in ten eyes, but function was limited to a low level as a result of the underlying ischemic disease. Immediate reattachment surgery in combination with anterior/peripheral coagulation therapy was shown to be an effective measure for controlling iris neovascular activity in eyes afflicted with acute anterior ocular neovascularization.

During the past 2 years, 44 patients (71 eyes) had pan-retinal photocoagulation by argon gas laser for proliferative diabetic retinopathy. All except 9 eyes benefitted from the treatment, peripheral and disc vessels showing regression. Many of the patients needed, or will need, further laser treatment. The main complications of treatment were slight or moderate constriction of the visual field, poor night vision and macular oedema.

Diabetic papillopathy has been characterized as a syndrome in which predominantly young, insulin-dependent diabetics develop transient edema of the optic disc with minimal impairment of the function of the optic nerves. In this study, four patients with long-standing insulin-dependent diabetes mellitus and acute disc swelling in one or both eyes were evaluated. The most unusual finding in these cases was that three had proliferative retinopathy either at the time the disc edema was discovered or very shortly afterwards. The fourth patient also developed this condition subsequently. It is important to be aware of diabetic papillopathy and to recognize the condition early enough so that the patient may be spared unnecessarily extensive neurological evaluations and invasive procedures. Patients with diabetic papillopathy should be closely observed so that the presence or development of proliferative retinopathy may be established.

Six patients are described, each of whom underwent early vitrectomy for advanced, active, proliferative diabetic retinopathy (PDR) in an eye with useful vision. These cases were selected to illustrate the spectrum of retinopathy severity for which early vitrectomy should be considered and the favorable outcome that can follow this procedure. None of the eyes that had an unfavorable result after early vitrectomy is presented. The eyes most suitable for early vitrectomy are those in which both fibrous proliferations and at least moderately severe new vessels are present, and in which extensive scatter photocoagulation has already been carried out or is precluded by vitreous hemorrhage.

The authors reviewed four cases of iatrogenic subretinal neovascularization after focal argon green photocoagulation for clinically significant diabetic macular edema. An inappropriate combination of small spot size with a high-power setting is the common feature in each case of iatrogenic subretinal neovascularization. Close follow-up with fluorescein angiography is used to identify iatrogenic subretinal neovascularization at an early, treatable stage. All four patients responded favorably to laser photocoagulation of the subretinal neovascular membrane.

In a retrospective study, 2688 eyes treated with xenon arc photocoagulation which would have qualified for inclusion in the Diabetic Retinopathy Study (DRS) were reviewed in the format of the DRS. When comparable risk groups were compared, the results of treatment were even more favorable than reported in the DRS without the severe complications attributed to xenon treatment in the DRS. A critical analysis of the DRS gives clues for the greater amount of visual loss found with xenon than argon in the DRS. Since these complications may be avoidable in some cases, and since xenon has been shown to be at least as effective as argon, it should continue to be used in the treatment of proliferative diabetic retinopathy.

The effect of 100% oxygen breathing on retinal blood flow was investigated using laser Doppler velocimetry in 19 normal eyes, and in 41 eyes of insulin treated diabetic patients. Of the diabetic eyes studied, nine had no retinopathy, 18 had background diabetic retinopathy, seven had proliferative diabetic retinopathy, and seven had proliferative diabetic retinopathy that had been previously treated by argon panretinal photocoagulation. Five minutes of 100% oxygen breathing produced an average decrease in blood flow of 61% (SD = 8) in normal eyes, 53% (SD = 10) in NR eyes, 38% (SD = 13) in background diabetic retinopathy eyes, 24% (SD = 18) in proliferative diabetic retinopathy eyes and 54% (SD = 8) in panretinal photocoagulation eyes. In six eyes with proliferative retinopathy measured before and after panretinal photocoagulation, a significant increase in vascular response to O2 was observed following photocoagulation (Wilcoxon signed rank test, P less than 0.05).

Early vitrectomy was carried out in 22 eyes with proliferative diabetic retinopathy and evidence of partial vitreous detachment in 17 patients with insulin-dependent diabetes. All the eyes had undergone panretinal laser photocoagulation, and all had a visual acuity of 6/12 or better, but 13 had had a vitreous hemorrhage. After a mean follow-up period of 29 months 19 of the eyes had retained the same visual acuity, 18 had been free of renewed vitreous hemorrhage for 6 months, there had been no macular retinal detachments and all the anterior segments were normal. The three instances of persistent visual loss were due to recurrent vitreous hemorrhage.

The visual function and degree of retinopathy was assessed, over a three-year period, in a cohort study of twenty-eight diabetics, in whom glycaemic control was improved by intensive monitoring and supervision of conventional therapies. With the exception of visual acuity and some tests of visual field sensitivity, there was no significant change in visual functions or retinopathy; with improved control of blood glucose, these two visual functions showed a small initial deterioration and subsequently returned towards starting values. Six subjects required laser photocoagulation for progressive peripheral neovascularisation (including two subjects with peripheral new vessels), the six having a significantly longer duration of diabetes, slightly worse measures of extra-foveal retinal functions and a significantly greater reduction in haemoglobin A1 concentration during the first six months of the study. In this study, the improvement of blood glucose control by intensive supervision of conventional therapy did not appear to be associated with the significant acute deterioration of visual function or retinopathy that has been reported with the strict diabetic control by multiple daily insulin injections or continuous subcutaneous insulin infusion.

Between 1982 and 1985, cataract extraction was performed on 144 eyes of 122 diabetics, and the early and late complications of the operation were recorded. There was seldom any intraoperative hemorrhaging or any postoperative anterior chamber hemorrhaging. On the first day after the operation, increased IOP was measured more frequently in diabetic patients than in those without diabetes. Diabetic retinopathy deteriorated in 12 eyes, while hemorrhaging glaucomas occurred in 5 eyes.

Fifty eyes of patients with proliferative diabetic retinopathy were followed at frequent intervals to determine the rapidity and stability of retinopathy risk factor regression after argon laser panretinal photocoagulation. Retinopathy risk factors regress rapidly after laser photocoagulation. The incidence of eyes at high risk for severe visual loss (eyes with 3 or more retinopathy risk factors) decreased from 100% prior to treatment to 28% three weeks after treatment. The early response to treatment was a good prognostic indicator of longer term results. Seventy-two percent of eyes which improved from a high- to a low-risk category by three weeks continued to remain at low risk at six months. Sixty-four percent of eyes which failed to improve to a low-risk category by three weeks continued to remain at high risk at six months. The early response to laser panretinal ablation may be used to predict longer-term results.

Transconjunctival anterior retinal cryotherapy (ARC) for proliferative diabetic retinopathy (PDR) in 408 eyes was reviewed retrospectively. Of 266 eyes available for analysis for treatment effect on neovascularization, 138 (52%) had reduced neovascularization at 6 months. Eighty (30%) had no change in neovascularization, and 48 (18%) had increased neovascularization at 6 months. Factors having a significant effect on reduction of neovascularization were duration of diabetes and severity of retinopathy. Of 238 eyes available for analysis for treatment effect on vitreous hemorrhage at 6 months, 118 (50%) had reduced vitreous hemorrhage, 80 (33%) had no change, and 40 (17%) had increased vitreous hemorrhage. Severity of vitreous hemorrhage significantly affected the outcome in the subgroup of eyes with both neovascularization and vitreous hemorrhage. Of the total 408 eyes in this series, at 6 months, 172 (44%) had improved visual acuity, 89 (23%) had no change, and 126 (33%) had decreased visual acuity. Retinal detachments developed in 17 eyes (4%) post-treatment, 68 eyes (17%) had significant recurrent vitreous hemorrhage, and 61 eyes (15%) eventually underwent vitrectomy.

Three hundred seventy eyes with advanced, active, proliferative diabetic retinopathy (PDR) and visual acuity of 10/200 or better were randomly assigned to either early vitrectomy or conventional management. After 4 years of follow-up, the percentage of eyes with a visual acuity of 10/20 or better was 44% in the early vitrectomy group and 28% in the conventional management group. The proportion with very poor visual outcome was similar in the two groups. The advantage of early vitrectomy tended to increase with increasing severity of new vessels. In the group with the least severe new vessels, no advantage of early vitrectomy was apparent.

The course of the vitreoretinal relationship in 272 eyes with diabetic retinopathy was studied retrospectively in an attempt to identify the prognostic role of the vitreous. In eyes with initial nonproliferative diabetic retinopathy, the development of neovascularization had a positive correlation with eventual partial posterior vitreous detachment (PVD) and a negative correlation with complete PVD. In eyes with initial proliferative diabetic retinopathy, those with active vitreous changes had a poor prognosis and those with inactive vitreous changes, an apparently good prognosis. Photocoagulation for retinal neovascularization was successful in most eyes with stable no-PVD but less successful in eyes that progressed to partial PVD. Therefore, considering the diabetic vitreous changes from a prognostic standpoint, the data suggest that if early proliferative changes are observed, photocoagulation before partial PVD develops might be considered.

Xenon arc and argon laser photocoagulation are equally effective in producing regression of disc neovascularization and maintaining visual acuity. Xenon has more destructive effects on the visual field and electroretinogram, but is more comfortable because retrobulbar anaesthesia is used and more convenient to the patient because fewer treatment sessions are needed.

A group of 20 patients (28 eyes) with proliferative retinopathy who required extensive argon laser photocoagulation to induce regression of new vessels is presented. The mean number of burns applied to each eye was 7225, with a maximum of 11,513. These were delivered in a mean of nine sessions over a mean period of 22.9 months. Twenty-five eyes (89%) had a final visual acuity of 6/18 or better. The remaining three eyes (11%) had severely reduced vision attributable to complications of proliferative diabetic retinopathy (traction retinal detachment involving the macula in two eyes and ischaemic maculopathy and a persistent vitreous haemorrhage in the third). Large amounts of confluent argon laser photocoagulation may be necessary for the elimination of new vessels in some patients, and it is our view that laser photocoagulation should be continued until regression of new vessels occurs. This is compatible with the retention of functional vision and good visual acuity.

We studied the ultrastructural characteristics of 23 vascularized preretinal membranes removed from 22 eyes during pars plana vitrectomy for proliferative diabetic retinopathy. Traction detachment of the macula was the most frequent reason for surgery (15 of 22 eyes), followed by nonclearing vitreous hemorrhage (seven of 22 eyes). Vessels found in the membranes were studied by serial sectioning and categorized as having either developing, mature, or regressing characteristics. Developing vessels were seen in ten of 23 membranes (43%), mature vessels in 19 of 23 membranes (83%), and regressing vessels in 13 of 23 membranes (57%). Endothelial fenestrations and cell separations were rare. With three-dimensional reconstruction, we found that new vessels often extended cytoplasmic processes into the extracellular matrix and that lumina were present even at the distalmost tips of the vessels. Solid cords of endothelial cells were not seen. We concluded that in proliferative diabetic retinopathy, new vessels develop by a process of focal extracellular matrix degradation, generalized and exuberant extracellular matrix production, cytoplasmic microvillus extension into the extracellular matrix, and active lumen formation.

During the past two decades, the number of diabetic patients requiring vitrectomy for nonresolving vitreous hemorrhage has decreased four-fold, whereas there has been a substantial increase in diabetic patients with traction and combined traction/rhegmatogenous retinal detachment (RD) requiring surgery. Additional contemporary surgical indications are progressive fulminant neovascular proliferation, massive preretinal hemorrhage, massive fibrin response, and progressive retrolental fibrovascular proliferation. Surgical techniques for management of tractional detachments have evolved from circumscription of tractional epicenters to en bloc removal of all proliferative tissue.

The authors treated 1007 eyes with vitrectomy for complications of proliferative diabetic retinopathy. Indications for surgery were: vitreous hemorrhage, 353 eyes (35%); traction retinal detachment, 360 eyes (36%); combined traction-rhegmatogenous retinal detachment, 172 eyes (17%); and other progressive fibrovascular proliferation 122 eyes (12%). During the study period, the frequency of vitreous hemorrhage as an indication for surgery decreased from 42 to 25%, and other progressive fibrovascular proliferation increased from 5 to 22%. The frequency of traction and traction/rhegmatogenous retinal detachments did not change. The results of surgery varied according to the indication. Seventy-nine percent of eyes with vitreous hemorrhage obtained final vision of 5/200 or better. Similar results were obtained in 64% of eyes with traction detachment, 56% of eyes with rhegmatogenous detachment, and 81% of eyes with progressive fibrovascular proliferation. The percentage of eyes achieving final vision of 20/100 or better are as follows: vitreous hemorrhage, 48%; traction detachment, 27%; rhegmatogenous detachment, 24%; and progressive fibrovascular proliferation, 46%. The success rate improved in each anatomic category during the last 3 years of the study.

Patients with long-standing diabetes develop acquired colour vision defects in parallel with retinal vascular changes. This may take the form of an overall loss of hue discrimination or a specific tritan (blue) defect. A battery of colour vision tests can be used to monitor the different features of diabetic retinopathy and to assess the effects of treatment. Diabetic disc new vessels form when approximately a quarter of the retina is ischaemic. The colour vision defect in these patients is usually severe and is frequently tritanopic. The effect of both argon laser and xenon arc panretinal photocoagulation is to increase the severity of the colour defect. All the eyes examined were tritanopic after treatment and did not recover during the 12-month follow-up period. The severity of this acquired colour vision defect can result in practical difficulties for the patient.

Since 1977, the author has treated proliferative diabetic retinopathy (PDR) under a protocol using DRS-style panretinal photocoagulation (PRP), with supplemental PRP, panretinal cryotherapy, and vitrectomy as needed. A total of 55 eyes (33 patients) were started on this protocol between 1/1/77 and 4/30/82. Follow-up averages 33 months (range: 12-80 months). Forty-nine eyes (89%) required PRP only; two eyes received panretinal cryotherapy, and four had vitrectomies. Visual acuity was maintained or improved in 44 eyes (80%); 48 eyes (87%) retained visual acuity of 20/100 or better. The major cause of visual loss was diabetic maculopathy.

Clinical research utilizing the yellow, orange, and red wavelengths of the liquid organic dye laser has demonstrated that this laser may be successfully used for photocoagulation of certain ophthalmic defects. The advantage of the dye laser as a photocoagulation source is its capability to produce monochromatic wavelengths at relatively high output powers through a large range of the visible spectrum. Therefore, a target tissue can be coagulated with minimal transmittal of laser energy through the ocular media, by the selection of a wavelength that would be most highly absorbed by that tissue. The dye laser, as a system that permits transspectral photocoagulation, should prove valuable in the treatment of ocular disease.