Early retinopathy progression in four randomized trials comparing insulin glargine and NPH [corrected] insulin

Early worsening of diabetic retinopathy, characterized by cotton wool spots, intraretinal microvascular abnormalities and/or macular edema, can occur following improvement of glycemic control. In four randomized 28- to 52-week clinical trials comparing insulin glargine and NPH insulin in regard to glycemic control and frequency of hypoglycemia, ophthalmologic examinations and fundus photographs were included to assess frequency of early worsening of retinopathy or other early adverse ocular effects. Retinopathy progression rates at 28 weeks were 7-12% by clinical examination and 3-8% by photographic grading; corresponding rates of clinically significant macular edema (CSME) were 1-8% and 1-4%, respectively. Optic disc swelling was not observed clinically or in photographs. Two of the 24 possible comparisons (four trials, three outcomes, two assessment methods), both of which were photographic assessments in type 2 diabetes, were in/near the nominally significant range and favored NPH insulin: 28-week rates of >or=3-step retinopathy progression (insulin glargine: 16/213, 7.5%; NPH insulin: 6/220, 2.7%; p=0.028) and 52-week CSME rates (26/233, 11.2% and 14/214, 6.5%, respectively; p=0.098). Because the between-treatment differences were small and inconsistent across trials and assessment methods, and because overall rates were consistent with the natural course of diabetic retinopathy, we conclude that it is unlikely that insulin glargine carries a higher risk of early worsening or other early adverse effect than NPH insulin. These trials tended to exclude a large early adverse effect, such as optic disc swelling, but cannot assess longer-term effects; a 5-year randomized trial of insulin glargine versus NPH insulin has been initiated. Data from this manuscript have been presented as posters and published in abstract form at the European Association for the Study of Diabetes 2001 ( DIABETOLOGIA 44(Suppl 1):I-IV(A287), 2001) and the Latin American Diabetes Association 2001 (11-15 November 2001, Punta del Este, Uruguay; Poster 180) congresses.

Results after lens extraction in patients with diabetic retinopathy: early treatment diabetic retinopathy study report number 25

OBJECTIVE

To assess the visual results after surgical lens removal in patients with diabetic retinopathy.

DESIGN

A multicenter randomized clinical trial designed to assess the effect of photocoagulation and aspirin in patients with mild to severe nonproliferative or early proliferative diabetic retinopathy and/or macular edema.

PARTICIPANTS

Of the 3711 patients enrolled in the Early Treatment Diabetic Retinopathy Study, lens surgery was performed on 205 patients (270 eyes) during follow-up that ranged from 4 to 9 years.

OUTCOME MEASUREMENTS

Visual acuity, macular edema status, and degree of diabetic retinopathy. In addition, risk factors associated with lens extraction and with poor postoperative visual acuity (worse than 20/100) were assessed.

RESULTS

The risk of lens extraction increased with increasing age, female sex, and baseline proteinuria. Ocular variables associated with increased risk of lens surgery included poor baseline visual acuity and vitrectomy performed during the course of the study. At 1 year after lens surgery, visual acuity improvement of 2 or more lines from preoperative levels occurred in 64.3% of the operated-on eyes assigned to early photocoagulation and 59.3% of eyes assigned to deferral of photocoagulation. In eyes assigned to early photocoagulation, 46% of eyes achieved visual acuity better than 20/40; 73%, better than 20/100; and 8%, 5/200 or worse at 1 year after surgery. Visual acuity results for eyes assigned to deferral of laser photocoagulation at 1 year were not as favorable; 36% achieved visual acuity better than 20/40; 55%, better than 20/100; and 17%, 5/200 or worse at 1 year after surgery. Evaluation of 1-year postoperative visual acuities for all eyes with mild to moderate nonproliferative diabetic retinopathy at the annual visit before lens surgery showed that 53% were better than 20/40; 90%, better than 20/100; and 1%, 5/200 or worse. However, for eyes with severe nonproliferative or worse retinopathy at the annual visit before lens surgery, only 25% were better than 20/40; 42%, better than 20/100; and 22%, 5/200 or worse at 1 year after lens surgery. There was little change in visual acuity between 1 and 2 years postoperatively. Increased severity of retinopathy and poor visual acuity before surgery were associated with visual acuity of worse than 20/100 at 1 year after surgery. Lens surgery was associated with a borderline statistically significant increased risk of progression of diabetic retinopathy in the adjusted analyses (P = .03). No statistically significant long-term increased risk of macular edema was documented after lens surgery.

CONCLUSIONS

Visual acuity results after lens surgery in patients in the Early Treatment Diabetic Retinopathy Study were better than published results for similar patients. This may be because of more intensive photocoagulation for lesions of diabetic retinopathy in the Early Treatment Diabetic Retinopathy Study than in previously reported studies. Although patients with severe nonproliferative retinopathy or worse before lens surgery had poorer visual results, visual improvement was seen in 55% of these patients at 1-year follow-up. The main causes of poor visual results in eyes after lens surgery were complications of proliferative retinopathy and/or macular edema.

Causes of severe visual loss in the early treatment diabetic retinopathy study: ETDRS report no. 24. Early Treatment Diabetic Retinopathy Study Research Group

PURPOSE

To describe the causes of and risk factors for persistent severe visual loss occurring in the Early Treatment Diabetic Retinopathy Study (ETDRS).

METHODS

The ETDRS was a randomized clinical trial investigating photocoagulation and aspirin in 3,711 persons with mild to severe nonproliferative or early proliferative diabetic retinopathy. Severe visual loss, defined as best-corrected visual acuity of less than 5/200 on at least two consecutive 4-month follow-up visits, developed in 257 eyes (219 persons). Of these 257 eyes, 149 (127 persons) did not recover to 5/200 or better at any visit (persistent severe visual loss). Ocular characteristics of these eyes were compared with those of eyes with severe visual loss that improved to 5/200 or better at any subsequent visit. Characteristics of patients with severe visual loss that did and did not improve and those without severe visual loss were also compared.

RESULTS

Severe visual loss that persisted developed in 149 eyes of 127 persons. In order of decreasing frequency, reasons recorded for persistent visual loss included vitreous or preretinal hemorrhage, macular edema or macular pigmentary changes related to macular edema, macular or retinal detachment, and neovascular glaucoma. Compared with all patients without persistent severe visual loss, patients with persistent severe visual loss had higher mean levels of hemoglobin A1c (10.4% vs 9.7%; P = .001) and higher levels of cholesterol (244.1 vs 228.5 mg/dl; P = .0081) at baseline. Otherwise, patients with persistent severe visual loss were similar to patients with severe visual loss that improved and to those without severe visual loss.

CONCLUSIONS

Persistent severe visual loss was an infrequent occurrence in the ETDRS. Its leading cause was vitreous or preretinal hemorrhage, followed by macular edema or macular pigmentary changes related to macular edema and retinal detachment. The low frequency of persistent severe visual loss in the ETDRS is most likely related to the nearly universal intervention with scatter photocoagulation (either before or soon after high-risk proliferative diabetic retinopathy developed) and the intervention with vitreous surgery when clinically indicated.

Risk factors for high-risk proliferative diabetic retinopathy and severe visual loss: Early Treatment Diabetic Retinopathy Study Report #18

PURPOSE

To identify risk factors for the development of high-risk proliferative diabetic retinopathy (PDR) and for the development of severe visual loss or vitrectomy (SVLV) in eyes assigned to deferral of photocoagulation in the Early Treatment Diabetic Retinopathy Study (ETDRS).

METHODS

Multivariable Cox models were constructed to evaluate the strength and statistical significance of baseline risk factors for development of high-risk PDR and of SVLV.

RESULTS

The baseline characteristics identified as risk factors for high-risk PDR were increased severity of retinopathy, decreased visual acuity (or increased extent of macular edema), higher glycosylated hemoglobin, history of diabetic neuropathy, lower hematocrit, elevated triglycerides, lower serum albumin, and persons with mild to moderate nonproliferative retinopathy, younger age (or type 1 diabetes). The predominant risk factor for development of SVLV was the prior development of high-risk PDR. The only other clearly significant factor was decreased visual acuity at baseline. In the eyes that developed SVLV before high-risk proliferative retinopathy was observed, baseline risk factors were decreased visual acuity (or increased extent of macular edema), older age (or type 2 diabetes), and female gender.

CONCLUSIONS

These analyses supported the view that the retinopathy-inhibiting effect of better glycemic control extends across all ages, both diabetes types, and all stages of retinopathy up to and including the severe nonproliferative and early proliferative stages and the possibility that reducing elevated blood lipids and treating anemia slow the progression of retinopathy.

Ganciclovir implant exchange. Timing, surgical procedure, and complications

BACKGROUND

The ganciclovir implant is effective for the treatment of cytomegalovirus (CMV) retinitis. The device eventually runs out of drug, however, and must be replaced. We report our experience with exchanging ganciclovir implants during the course of a randomized clinical trial.

METHODS

During our study, patients with newly diagnosed peripheral CMV retinitis were treated with a ganciclovir implant. The implant was scheduled for exchange at 32 weeks. It was exchanged earlier if progression of CMV retinitis occurred. Patient examinations and standard fundus photography were performed at 2-week intervals after the exchange procedure.

RESULTS

Twenty-six exchange procedures were performed. Twenty-two eyes in 15 patients received a second implant and 4 eyes in 4 patients later received a third implant. Cytomegalovirus retinitis was rendered or maintained inactive in 22 of 23 cases with more than 1 month of follow-up after the second or third implants. Complications after the second implant procedure included transient vitreous hemorrhage in 5 eyes, postoperative inflammation in 1 eye, and retinal detachment in 1 eye. Median visual acuity returned to 20/25 by 28 days and to 20/20 by 42 days. Complications after the third implant procedure included dense vitreous hemorrhage in 3 of 4 eyes. Median survival time after a second implant procedure was 89 days.

CONCLUSIONS

The initial ganciclovir implant exchange procedure is well tolerated with continued long-term control of CMV retinitis. Multiple reentries through the same wound may be associated with an increased risk for vitreous hemorrhage.

Cigarette smoking and the risk of development of lens opacities. The Framingham studies

OBJECTIVE

To examine the association between cigarette smoking and the incidence of nuclear and non-nuclear lens opacities in members of the Framingham Eye Study Cohort.

PARTICIPANTS AND METHODS

Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Smoking data, collected biennially since 1948 in the Heart Study, were used to examine the relationship between cigarette smoking and the incidence of lens opacities. Two thousand six hundred seventy-five persons were examined in the Framingham Eye Study I. Our analysis included 660 persons, aged 52 to 80 years, who were free of lens opacities at the first eye examination.

RESULTS

During the approximately 12.5 years between eye examinations, lens opacities developed in a total of 381 persons, with nuclear opacities constituting the most frequent type. In logistic regression analyses that controlled for age, sex, education, and diabetes, a significant positive association with increasing duration of smoking and number of cigarettes smoked daily was found for nuclear lens opacities, alone or in combination (test for trend, P < or = .002), but not for nonnuclear opacities (test for trend, P = .62). Among the heavier smokers (persons who smoked > or = 20 cigarettes per day according to 6 or more biennial Framingham Heart Study examinations), 77% were still smoking at the time of the first eye examination. Persons who smoked 20 or more cigarettes per day at the time of the first eye examination were at substantially increased risk for the development of nuclear opacities than nonsmokers (odds ratio, 2.84; 95% confidence interval, 1.46-5.51). There was no apparent excess risk for persons with nonnuclear lens opacities (odds ratio, 1.42; 95% confidence interval, 0.65-3.07).

CONCLUSION

This study provides further evidence that cigarette smokers have an increased risk of developing nuclear lens opacities. The risk was greatest for heavier smokers, who tended to be current smokers and who smoked more cigarettes and for a longer duration.

Subretinal fibrosis in diabetic macular edema. ETDRS report 23. Early Treatment Diabetic Retinopathy Study Research Group

OBJECTIVE

To describe the characteristics of and risk factors for subretinal fibrosis (SRF) in patients with diabetic macular edema.

PATIENTS AND METHODS

A total of 109 eyes (in 96 persons) with SRF, defined as a mound or sheet of gray to white tissue beneath the retina at or near the center of the macula, were identified during the Early Treatment Diabetic Retinopathy Study, which is a randomized clinical trial of photocoagulation and aspirin treatment in patients with mild to severe nonproliferative or early proliferative diabetic retinopathy. The patients and the ocular characteristics of these 109 eyes, all of which had clinically significant macular edema, were compared with those of 5653 eyes in which clinically significant macular edema, but not SRF, was observed during the trial.

RESULTS

In 9 of 109 eyes, the development of SRF may have been directly related to focal photocoagulation. Seventy-four percent of the eyes in which SRF developed had very severe hard exudates in the macula prior to the development of SRF, while this level of hard exudates was seen in only 2.5% of the eyes with clinically significant macular edema in which SRF did not develop (P < .001). Of the 264 eyes with this level of hard exudates at baseline (n = 29) or during follow-up (n = 235), SRF developed in 30.7% of the eyes, while this complication developed in only 0.05% of 5498 eyes with clinically significant macular edema without this level of hard exudates.

CONCLUSIONS

Subretinal fibrosis is an infrequent complication of diabetic macular edema. Although it has been reported to be associated with photocoagulation burn intensity, in only 9 of 109 eyes in which SRF developed was it located adjacent to a photocoagulation-related scar (among 4823 eyes that received focal photocoagulation for treatment of macular edema). The strongest risk factor for the development of SRF is very severe hard exudate.

Treatment of uveitis by oral administration of retinal antigens: results of a phase I/II randomized masked trial

PURPOSE

To evaluate the effect and safety of the oral administration of retinal antigens as a treatment of ocular inflammation.

METHODS

In a phase I/II randomized masked trial, patients with endogenous uveitis who were dependent on immunosuppressive agents were randomly assigned to receive either retinal S antigen alone (10 patients), retinal S antigen and a mixture of soluble retinal antigens (10 patients), a mixture of soluble retinal antigens alone (10 patients), or placebo (15 patients). An attempt was then made to taper patients completely off their standard immunosuppressive therapy over an 8 week period. The primary study endpoint was time to ocular inflammatory attack. The secondary study endpoint was the ability to taper patients completely off their immunosuppressive or cytotoxic medication within 8 weeks.

RESULTS

Time to development of the main study endpoint was not statistically significantly different for any of the four treatment groups. However, the group receiving the purified S antigen alone appeared to be tapered off their immunosuppressive medication more successfully compared with patients given placebo (P = .08), whereas all the other groups appeared to do worse than did those receiving placebo. No toxic effects attributable to any treatment were observed.

CONCLUSIONS

This phase I/II study is the first to test the use of orally administered S antigen in the treatment of uveitis. Although not statistically significant, patients given S antigen were more likely to be tapered off their chronically administered systemic immunosuppressive therapy than were the other groups tested.

Association of elevated serum lipid levels with retinal hard exudate in diabetic retinopathy. Early Treatment Diabetic Retinopathy Study (ETDRS) Report 22

OBJECTIVE

To evaluate the relationship between serum lipid levels, retinal hard exudate, and visual acuity in patients with diabetic retinopathy.

DESIGN

Observational data from the Early Treatment Diabetic Retinopathy Study.

PARTICIPANTS

Of the 3711 patients enrolled in the Early Treatment Diabetic Retinopathy Study, the first 2709 enrolled had serum lipid levels measured.

MAIN OUTCOME MEASURES

Baseline fasting serum lipid levels, best-corrected visual acuity, and assessment of retinal thickening and hard exudate from stereoscopic macular photographs.

RESULTS

Patients with elevated total serum cholesterol levels or serum low-density lipoprotein cholesterol levels at baseline were twice as likely to have retinal hard exudates as patients with normal levels. These patients were also at higher risk of developing hard exudate during the course of the study. The risk of losing visual acuity was associated with the extent of hard exudate even after adjusting for the extent of macular edema.

CONCLUSIONS

These data demonstrate that elevated serum lipid levels are associated with an increased risk of retinal hard exudate in persons with diabetic retinopathy. Although retinal hard exudate usually accompanies diabetic macular edema, increasing amounts of exudate appear to be independently associated with an increased risk of visual impairment. Lowering elevated serum lipid levels has been shown to decrease the risk of cardiovascular morbidity. The observational data from the Early Treatment Diabetic Retinopathy Study suggest that lipid lowering may also decrease the risk of hard exudate formation and associated vision loss in patients with diabetic retinopathy. Preservation of vision may be an additional motivating factor for lowering serum lipid levels in persons with diabetic retinopathy and elevated serum lipid levels.

Digoxin does not accelerate progression of diabetic retinopathy

OBJECTIVE

To test the hypothesis that digoxin, an inhibitor of Na(+)-K(+)-ATPase activity, accelerates the progression of diabetic retinopathy.

RESEARCH DESIGN AND METHODS

We compared the incidence and risk of retinopathy in 120 digoxin-taking vs. 867 non-digoxin-taking diabetic participants in the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) and in 117 digoxin-taking vs. 1,883 non-digoxin-taking diabetic subjects in the Early Treatment Diabetic Retinopathy Study (ETDRS). In both studies, retinopathy was detected by grading stereoscopic color photographs using the modified Airlie House classification scheme, and a two-step difference in baseline retinopathy grade was considered significant.

RESULTS

After controlling for other risk factors, we found no statistically significant association with either 4-year incidence of retinopathy (WESDR) or progression of retinopathy (WESDR and ETDRS) in patients taking digoxin at baseline compared with those not taking digoxin.

CONCLUSIONS

These data suggest that digoxin therapy does not adversely affect the course of diabetic retinopathy.

Effects of aspirin on vitreous/preretinal hemorrhage in patients with diabetes mellitus. Early Treatment Diabetic Retinopathy Study report no. 20

OBJECTIVE

To assess whether the use of aspirin exacerbates the severity or duration of vitreous/preretinal hemorrhages in patients with diabetic retinopathy.

DESIGN

The Early Treatment Diabetic Retinopathy Study (ETDRS), a multicenter randomized clinical trial, was designed to assess the effect of photocoagulation and aspirin on 3711 patients with mild to severe nonproliferative or early proliferative diabetic retinopathy.

INTERVENTION

Patients were randomly assigned to either an aspirin (650 mg/d) or a placebo group. One eye of each patient was randomly assigned to early photocoagulation and the other to deferral of photocoagulation.

MAIN OUTCOME MEASURES

The severity and duration of the vitreous/preretinal hemorrhages were determined from gradings of the annual, seven standard stereoscopic field, fundus photographs. Clinical examinations scheduled every 4 months also provided information on the presence and duration of hemorrhages.

RESULTS

Annual fundus photographs of eyes assigned to deferral of photocoagulation revealed vitreous/preretinal hemorrhages at some time during follow-up in 564 patients (30%) assigned to the placebo group and 585 patients (32%) assigned to the aspirin group (P = .48). Based on gradings of fundus photographs, there were no statistical differences in the severity of vitreous/preretinal hemorrhages (P = .11) or their rate of resolution (P = .86) between the groups. Clinical examination of eyes assigned to deferral of photocoagulation revealed 721 eyes (39%) assigned to the aspirin group and 689 (37%) assigned to the placebo group that had vitreous/preretinal hemorrhages during the course of the study (P = .30). Again, no statistically significant difference was found between the rates of resolution, as assessed clinically, between the two treatment groups (P = .43).

CONCLUSIONS

As previously reported, the use of aspirin did not increase the occurrence of vitreous/preretinal hemorrhages in patients enrolled in the ETDRS. The data presented in this report demonstrate that the severity and duration of these hemorrhages were not significantly affected by the use of aspirin and that there were no ocular contraindications to its use (650 mg/d) in persons with diabetes who require it for treatment of cardiovascular disease or for other medical indications.

Accommodative amplitudes in the Early Treatment Diabetic Retinopathy Study

PURPOSE

Accommodative amplitude in persons with diabetes was investigated using data collected as part of the Early Treatment Diabetic Retinopathy Study.

METHODS

Accommodative amplitude was measured at the baseline visit in 1,058 patients who had good visual acuity and who were less than 46 years old. Risk factors for low accommodative amplitude at baseline were evaluated using multivariable linear regression. Change in accommodative amplitude after photocoagulation was evaluated using paired t tests and repeated measures analysis of variance for the 578 patients who underwent follow-up measurements at the 4-month visit.

RESULTS

Accommodative amplitudes in Early Treatment Diabetic Retinopathy Study patients were lower than normal accommodative amplitudes. Older age (P < 0.001) and increased duration of diabetes (P < 0.01) were risk factors associated with low amplitudes of accommodation in the Early Treatment Diabetic Retinopathy Study. Full scatter photocoagulation was associated with an apparently transient additional reduction in accommodative amplitude; a one third diopter loss in accommodative amplitude was demonstrated only at the 4-month visit (P < 0.001).

CONCLUSION

This study demonstrates that diabetes and duration of diabetes, along with age, are important risk factors for reduced accommodative amplitude. These factors along with an apparently transient decrease in accommodative amplitude following scatter photocoagulation should be considered when assessing the accommodative needs of patients with diabetes and when discussing side effects of full scatter photocoagulation.

Treatment of cytomegalovirus retinitis with an intraocular sustained-release ganciclovir implant. A randomized controlled clinical trial

BACKGROUND AND METHODS

We performed a randomized controlled clinical trial to assess the safety and efficacy of a 1 microgram/h ganciclovir implant for the treatment of newly diagnosed cytomegalovirus (CMV) retinitis in patients with the acquired immunodeficiency syndrome (AIDS). Patients with previously untreated peripheral CMV retinitis were randomly assigned either to immediate treatment with the ganciclovir implant or to deferred treatment. Standardized fundus photographs were taken at 2-week intervals and analyzed in a masked fashion. The study end point was progression of retinitis based on the photographic assessment.

RESULTS

Twenty-six patients (30 eyes) were enrolled. The median time to progression of retinitis was 15 days in the deferred treatment group (n = 16) vs 226 days in the immediate treatment group (n = 14) (P < .00001, log-rank test). During the study, 39 primary implants and 12 exchange implants were placed in immediate-treatment eyes, deferred-treatment eyes that progressed, or contralateral eyes that developed CMV retinitis. Postoperative complications in the total series included seven late retinal detachments and one retinal tear without detachment. Final visual acuity was 20/25 or better in 34 of 39 eyes. The estimated risk of developing CMV retinitis in the fellow eye was 50% at 6 months. Biopsy-proven visceral CMV disease developed in eight (31%) of 26 patients. The median survival was 295 days.

CONCLUSION

The ganciclovir implant is effective for the treatment of CMV retinitis. Patients with unilateral CMV retinitis treated with the implant are likely to develop CMV retinitis in the fellow eye, and some patients will develop visceral CMV disease.

Results of 20 years of research on the treatment of diabetic retinopathy

Diabetic retinopathy is the leading cause of blindness in young adults, ages 20-55. Without treatment 50% of those with proliferative diabetic retinopathy will be blind within 5 years. Over the last 2 decades the National Eye Institute has supported four different multicenter randomized clinical trials for diabetic retinopathy. Implementation of the results from these clinical trials can markedly reduce the risk of blindness.

Preventive eye care in people with diabetes is cost-saving to the federal government. Implications for health-care reform

OBJECTIVE

Diabetic retinopathy, which leads to macular edema and retinal neovascularization, is the leading cause of blindness among working-age Americans. Previous research has demonstrated significant cost savings associated with detection of eye disease in Americans with type I diabetes. However, detection and treatment of eye disease among those with type II diabetes was previously thought not to be cost-saving. Our purpose was to estimate the current and potential federal savings resulting from the screening and treatment of retinopathy in patients with type II diabetes, based on recently available data concerning efficacy of treating both macular edema and neovascularization along with new data on federal budgetary costs of blindness.

RESEARCH DESIGN AND METHODS

We used computer modeling, incorporating data from population-based epidemiological studies and multicenter clinical trials. Monte Carlo simulation was used, combined with sensitivity analysis and present value analysis of cost savings.

RESULTS

Screening and treatment for eye disease in patients with type II diabetes generates annual savings of $247.9 million to the federal budget and 53,986 person-years of sight, even at current suboptimal (60%) levels of care. If all patients with type II diabetes receive recommended care, the predicted net savings (discounted at 5%) exceeds $472.1 million and 94,304 person-years of sight. Nearly all savings are associated with detection and treatment of diabetic macular edema. Enrolling each additional person with type II diabetes into currently recommended ophthalmological care results in an average net savings of $975/person, even if all costs of care are borne by the federal government.

CONCLUSIONS

Our analysis indicates that prevention programs aimed at improving eye care for patients with diabetes not only reduce needless vision loss but also will provide a financial return on the investment of public funds.

Relative letter and position difficulty on visual acuity charts from the Early Treatment Diabetic Retinopathy Study

Ten Sloan letters were used in the visual acuity charts developed for use in the Early Treatment Diabetic Retinopathy Study. We used the data from the 3,710 Early Treatment Diabetic Retinopathy Study subjects to investigate the relative difficulty of the ten Sloan letters and to evaluate whether the position of a letter on a line affected its relative difficulty. In general, our findings were consistent with those of the previous study. The four letters with curved contours (C, O, S, and D) were more difficult to discern at threshold than the six letters (Z, N, H, V, R, and K) composed of straight lines. Our data demonstrate that under these test conditions, letters at the end of a line are more likely to be read incorrectly than letters at the beginning of the line. This finding indicates that these data are probably not useful for evaluating possible crowding phenomena.

Issues in management of diabetic retinopathy

Panretinal photocoagulation could prevent most blindness from proliferative disease--if risk is identified early. This makes it essential that primary physicians include annual ophthalmologic evaluation in the management of patients at risk. Meanwhile, studies are under way on promising medical approaches, including intensive insulin regimens, aldose reductase blockers, and angiogenesis inhibitors.

Diabetic retinopathy

OBJECTIVE

To review the natural history and treatment indications for diabetic retinopathy.

RESEARCH DESIGN AND METHODS

Studies of the natural history of diabetic retinopathy and major clinical trials sponsored by the National Eye Institute were reviewed.

RESULTS

Diabetic retinopathy remains a leading cause of vision disability in the U.S. Vision loss results from the consequences of proliferative retinopathy or macular edema. Photocoagulation has been demonstrated to be an effective treatment for these complications of diabetes.

CONCLUSIONS

All people with diabetes should be evaluated regularly to determine whether they would benefit from photocoagulation. As a referral guideline, any person with type I diabetes of > 5 yr duration and all people with type II diabetes or any retinopathy should be referred to an ophthalmologist.

Pars plana vitrectomy in the Early Treatment Diabetic Retinopathy Study. ETDRS report number 17. The Early Treatment Diabetic Retinopathy Study Research Group

BACKGROUND

The Early Treatment Diabetic Retinopathy Study (ETDRS) enrolled 3711 patients with mild-to-severe nonproliferative or early proliferative diabetic retinopathy in both eyes. Patients were randomly assigned to aspirin 650 mg/day or placebo. One eye of each patient was assigned randomly to early photocoagulation and the other to deferral of photocoagulation. Follow-up examinations were scheduled at least every 4 months, and photocoagulation was initiated in eyes assigned to deferral as soon as high-risk proliferative retinopathy was detected. Aspirin was not found to have an effect on retinopathy progression or rates of vitreous hemorrhage. The risk of a combined end point, severe visual loss or vitrectomy, was low in eyes assigned to deferral (6% at 5 years) and was reduced by early photocoagulation (4% at 5 years). Vitrectomy was carried out in 208 patients during the 9 years of the study. This report presents baseline and previtrectomy characteristics and visual outcome in these patients.

METHODS

Information collected at baseline and during follow-up as part of the ETDRS protocol was supplemented by review of clinic charts for visual acuity and ocular status immediately before vitrectomy.

RESULTS

Vitrectomy was performed in 208 (5.6%) of the 3711 patients (243 eyes) enrolled in the ETDRS. The 5-year vitrectomy rates for eyes grouped by their initial photocoagulation assignment were as follows: 2.1% in the early full scatter photocoagulation group, 2.5% in the early mild scatter group, and 4.0% in the deferral group. The 5-year rates of vitrectomy (in one or both eyes) were 5.4% in patients assigned to aspirin and 5.2% in patients assigned to a placebo. The indications for vitrectomy were either vitreous hemorrhage (53.9%) or retinal detachment with or without vitreous hemorrhage (46.1%). Before vitrectomy, visual acuity was 5/200 or worse in 66.7% of eyes and better than 20/100 in 6.2%. One year after vitrectomy, the visual acuity was 20/100 or better in 47.6% of eyes, including 24.0% with visual acuity of 20/40 or better.

CONCLUSIONS

With frequent follow-up examinations and timely scatter (panretinal) photocoagulation, the 5-year cumulative rate of pars plana vitrectomy in ETDRS patients was 5.3%. Aspirin use did not influence the rate of vitrectomy.

Assessing the costs and benefits of medical research: the diabetic retinopathy study

Significant amounts of scarce resources are devoted to medical research, but there have been few attempts to assess whether the benefits to society of these investments exceed the costs. A method for undertaking such an assessment has been developed and applied retrospectively to the Diabetic Retinopathy Study, a major clinical trial funded by the National Eye Institute from 1972-1981. It was estimated that the trial, which cost $10.5 million, generated a net saving of $2816 million to society ($231 million when the costs of lost production are excluded) (1982 prices) and a gain to patients of 279,000 vision years. This approach could be applied prospectively in considering priorities for medical research, in conjunction with traditional criteria such as the scientific merit of the proposal and the capabilities of the investigators. The key factors affecting the economic returns from medical research are the prevalence, incidence and economic burden of the disease in question, the costs and effectiveness of the medical intervention concerned, the likely impact of the clinical trial on clinical practice and the likely timespan of benefits from knowledge obtained during the trial.

Aspirin effects on the development of cataracts in patients with diabetes mellitus. Early treatment diabetic retinopathy study report 16

The Early Treatment Diabetic Retinopathy Study, a randomized clinical trial supported by the National Eye Institute, was designed to assess the effect of photocoagulation and aspirin in 3711 patients with mild to severe nonproliferative or early proliferative diabetic retinopathy. Although the primary goal of the study was to evaluate the effect of photocoagulation and aspirin on diabetic retinopathy, the study also provided an opportunity to evaluate the effects of aspirin on the development of cataract. No evidence showed that aspirin use reduced the risk of development of cataract requiring extraction (4.1% vs 4.3% in patients assigned to aspirin or placebo treatment, respectively; Mantel-Cox P = .77; relative risk, 1.05; 99% confidence interval, 0.73 to 1.51). Aspirin use also did not reduce the risk of less extensive but visually significant lens opacities developing (29.6% vs 28.3%; Mantel-Cox P = .76; relative risk, 0.99; 99% confidence interval, 0.85 to 1.15). Early Treatment Diabetic Retinopathy Study results do not support the hypothesis that aspirin (at a dose of 650 mg/d) reduces the risk of cataract development in this diabetic population.

Factors associated with visual outcome after photocoagulation for diabetic retinopathy. Diabetic Retinopathy Study Report #13

Six risk factors for severe visual loss despite panretinal (scatter) photocoagulation were identified by analyzing data collected during the first 5 years after randomization in the Diabetic Retinopathy Study. Proportional hazards regression revealed NVD (neovascularization on/around the optic disc) to be the most important risk factor. The risk of severe visual loss rose with increasing NVD, hemorrhages/microaneurysms, retinal elevation, proteinuria, and hyperglycemia and fell with increasing "treatment density." These results are similar to previous DRS findings on untreated eyes. The importance of "treatment density" as an independent predictor of visual outcome is a new finding and lends support to the common clinical practice of repeating photocoagulation if initial treatment does not reduce or stabilize retinal neovascularization.

Krypton laser for proliferative diabetic retinopathy: the Krypton Argon Regression of Neovascularization Study

The Krypton Argon Regression of Neovascularization Study (KARNS) is a multicenter, randomized, controlled clinical trial designed to determine the efficacy of red krypton laser photocoagulation in the treatment of proliferative diabetic retinopathy.

Transient severe visual loss after panretinal photocoagulation

Seven diabetic patients experienced severe but transient visual loss after panretinal photocoagulation for proliferative diabetic retinopathy. In all patients, visual acuity decreased shortly after treatment to levels ranging from 5/200 to no light perception. In five of the patients, no observable ocular disease or surgical complications could explain the degree of visual loss. The other two patients developed exudative macular detachments, although it was not clear that this change accounted for their severe visual loss. Vision improved in all patients over a period ranging from nine days to nine months. In five patients, visual acuity returned to within two Snellen lines of the pretreatment level.

The early treatment of diabetic retinopathy

Advances in the understanding of diabetic retinopathy have allowed the development ofnew treatments directed at the preservation of sight. Recent data compiled by the Early Treatment Diabetic Reti nopathy Study (ETDRS) show that focal photocoagulation therapy can reduce the risk of further vision loss in diabetic patients with clinically significant macular edema. Therefore, treatment should be considered for all eyes that meet the criteria of clinically significant macular edema.

Optic disk neovascularization and retinal vessel diameter in diabetic retinopathy

We measured retinal vessel diameter before and after panretinal photocoagulation in 59 eyes with diabetic retinopathy and moderate to severe optic disk neovascularization. Treatment significantly reduced mean arteriolar and venular diameter. The diameter of the retinal arterioles after treatment correlated significantly with the amount of regression in disk neovascularization. Eyes with large diameter vessels after treatment usually had little or no regression of proliferative retinopathy, whereas regression was more frequently seen in eyes with smaller diameter vessels after treatment.

Diabetic retinopathy and cardiovascular disease in type II diabetics. The Framingham Heart Study and the Framingham Eye Study

Data from the Framingham Heart Study and the Framingham Eye Study were used to examine the association between diabetic retinopathy and the occurrence of cardiovascular events (coronary heart disease, intermittent claudication, congestive heart failure, and stroke). Among the 206 persons with Type II diabetes in the Framingham Eye Study, the odds ratios for diabetic retinopathy and cardiovascular disease were 14.3 (95% confidence interval (CI) = 2.7-101.9), 2.0 (95% CI = 0.5-8.1), and 0.3 (95% CI = 0.05-1.3) for ages 52-64, 65-74, and 75-85 years, respectively. The test for homogeneity indicated highly significant differences for the odds ratios across age groups. The associations were similar when sex, duration of diabetes, age at diagnosis of diabetes, and history of insulin treatment were accounted for by logistic regression. Our data suggest an association in younger diabetics between diabetic retinopathy, a small vessel complication of diabetes, and a group of cardiovascular events commonly thought to result from large vessel disease. The finding may merely indicate that diabetics with large vessel disease are also more likely to have small vessel disease. However, it is also consistent with the hypothesis, suggested by histologic data, that a more generalized microangiopathy affecting not only the eye but also organs such as the heart may play a role in the pathogenesis of cardiovascular disease in diabetics.

Macular thickening and visual acuity. Measurement in patients with cystoid macular edema

Cystoid macular edema (CME) is commonly associated with many ocular conditions. The presence of CME on fluorescein angiographic examination need not, however, preclude good visual acuity. The hypothesis that the degree of macular thickening is associated with visual acuity was tested. Ten consecutive stereoscopic fluorescein angiograms were graded by 13 ophthalmologists using a set of four standards. Linear regression showed a significant relationship between mean macular thickening and the visual acuity recorded at the time of angiography. However, no significant relationship could be made between the estimation of visual acuity and the amount of fluorescein staining measured in the posterior pole. Although the observation of fluorescein leakage is indispensable for documenting a breakdown in the blood-retinal barrier, the observation of retinal thickening is important for identifying the sites of edema accumulation, and may be the useful parameter to follow when trying to assess improvement or worsening of retinal edema and in cases of uveitis when the cause of poor vision may be multifactorial.

Macular edema in Diabetic Retinopathy Study patients. Diabetic Retinopathy Study Report Number 12

Results from the Diabetic Retinopathy Study (DRS) demonstrate that scatter photocoagulation is associated with some loss of visual acuity soon after treatment. This visual loss is especially prominent in eyes with preexisting macular edema. It is also associated with the intensity of treatment. Reducing macular edema by focal photocoagulation before initiating scatter treatment and dividing scatter treatment into multiple sessions with less intense burns may decrease the risk of the visual loss associated with photocoagulation.

Intraocular pressure following panretinal photocoagulation for diabetic retinopathy. Diabetic Retinopathy Report No. 11

Data collected during the first five years after randomization in the Diabetic Retinopathy Study were analyzed to determine the effect of panretinal photocoagulation on intraocular pressure (IOP). At each follow-up visit, median IOP was identical for the treated and untreated eyes. Mean IOP rose slightly in each group. The proportion of untreated eyes with IOP above 30 mm Hg at two consecutive visits was twice that of the treated eyes (2% vs 1%). These data show that panretinal photocoagulation reduces the risk of subsequent intraocular hypertension, apparently by preventing the development of neovascular glaucoma.

Clinical measurement of saturation discrimination

In this paper, we describe how a circular reflective neutral-density wedge can be used to construct an apparatus which provides a relatively rapid procedure for the clinical measurement of saturation discrimination. Subsequent to an initial measurement of the patient's relative luminosity function, the patient need only turn a single control which varies the colorimetric purity of a test field which remains luminance matched to a white light reference field.

Comparability of ophthalmic diagnoses by clinical and Reading Center examiners in the Visual Acuity Impairment Survey Pilot Study

Technologic advances in ophthalmic equipment offer the possibility of replacing direct clinical examinations with Reading Center evaluations of data recorded in epidemiologic studies. Clinical and Reading Center examiners made independent ophthalmic diagnoses of 133 right and 132 left eyes of 138 adults in the Visual Acuity Impairment Survey Pilot Study, carried out in three US cities, Boston, Detroit, and Minneapolis, in August 1981-December 1982. The Reading Center diagnosed eye conditions using only photographic and visual field data collected at the time of the clinical examination. In the comparisons of clinical and Reading Center evaluations reported here, only eyes judged by the examiners to have pathology severe enough to reduce visual acuity to 6/9 or worse were classified as having pathology. (No visual acuity criterion was required for the diagnosis of glaucoma or diabetic retinopathy.) There was agreement in diagnostic assessments between clinical and Reading Center examiners in about 80% of eyes. The kappa statistic, which adjusts for chance agreement, was in the fair to good range: 0.60 for 133 right eyes and 0.62 for 132 left eyes. When the Reading Center examiners were provided with additional information on medical history, refractive error and best corrected visual acuity, the agreement between clinical and Reading Center assessments among the subset of eyes with 6/9 or worse vision again was in the fair to good range, with kappas of 0.61 for 45 right eyes and 0.68 for 48 left eyes. Inter-observer agreement between Reading Center examiners in diagnosing pathology was in the good to excellent range. Use of Reading Centers in future epidemiologic studies should be considered, but elimination of the clinical examinations is not recommended until modifications in the protocol described here have been made and shown to improve levels of agreement between clinical and Reading Center examiners.

Evaluation of medical data: role of clinical trials

Over the centuries, methods have been developed to evaluate diseases and their treatments. One systematic method is the case series, in which groups of patients are followed over time to estimate the likelihood of various disease outcomes, either with or without treatment. A more efficient method for assessing treatment effectiveness is the clinical trial. Both methods have been used for evaluating current treatments of macular diseases. the combination of case series and clinical trials has been used to advantage for many of these diseases. However, when one wants to be certain that a treatment is effective, there is no substitute for the clinical trial.

Age-related macular degeneration and blindness due to neovascular maculopathy

Age-related macular degeneration (AMD) is one of the four most common causes of blindness in the United States. Retinal manifestations of AMD can be categorized as either atrophic or neovascular/exudative. To the best of our knowledge, the proportion of patients legally blind due to the neovascular/exudative manifestations of this disease has not been previously reported. Data from two studies, the Framingham Eye Study and a large case-control study, demonstrate that the vast majority of patients with legal blindness due to AMD have the neovascular/exudative form of the disease. Seventy-nine percent of eyes legally blind due to AMD in the Framingham population and 90% of eyes legally blind due to AMD in the case-control study had neovascular/exudative retinopathy. This is in spite of the fact that neovascular/exudative retinopathy is a relatively infrequent complication of AMD.