The Diabetic Retinopathy Study (DRS) was the first major initiative of the National Eye Institute. It was a multi-centre, randomized clinical trial designed to evaluate the safety and efficacy of panretinal photocoagulation (PRP) in reducing the risk of vision loss and blindness in patients with advanced diabetic retinopathy. 1758 patients were enrolled between 1972 and 1975.
Eligibility:
Patients were eligible if they had best corrected visual acuity of 20/100 or better in each eye and the presence of proliferative diabetic retinopathy in at least one eye or severe nonproliferative retinopathy in both eyes. They could not have had prior treatment with photocoagulation or pituitary ablation, and both eyes had to be suitable for photocoagulation. All eligible patients were younger than 70 years, and the examining physician assessed the outlook for survival and availability for 5 years of followup to be good.
Methodology:
One eye of each patient was randomly assigned to immediate photocoagulation and the other to followup without treatment, regardless of the course followed by either eye. The eye chosen for photocoagulation was randomly assigned to either of two treatment techniques, one using an argon laser and the other a xenon arc photocoagulator. Patients were followed at 4-month intervals according to a protocol that provided for measurement of best corrected visual acuity.
Treatment was usually completed in one or two sittings and included scatter (panretinal) photocoagulation extending to or beyond the vortex vein ampulae. The argon treatment technique specified 800 to 1,600, 500-micron scatter burns of 0.1 second duration and direct treatment of new vessels whether on or within one disc diameter of the optic disc (NVD) or outside this area (NVE). Focal treatment was also applied to microaneurysms or other lesions thought to be causing macular edema. Followup treatment was applied as needed at 4-month intervals. The xenon technique was similar, but scatter burns were fewer in number, generally of longer duration, and stronger, and direct treatment was applied only to NVE on the surface of the retina.
Results:
Primary Outcome:
Visual Acuity: Scatter photocoagulation with both argon and xenon arc reduced severe visual acuity loss (defined as visual acuity 5/200 or worse) by approximately 50% compared to no treatment throughout 5 years of follow-up.
Secondary Outcomes:
Progression of Retinopathy: Scatter photocoagulation with both argon and xenon reduced the rate of progression of eyes to more severe stages of proliferative diabetic retinopathy compared to no treatment.
IOP: Panretinal photocoagulation reduced the risk of elevated intraocular pressure, possibly preventing the development of neovascular glaucoma.
Risk Factors: Four risk factors were identified as increasing the risk of severe visual acuity loss in untreated eyes: (1) presence of vitreous or preretinal haemorrages; (2) presence of new vessels; (3) location of new vessels on or near the disc; (4) severity of new vessels. Of these neovascularisation of the disc had the strongest association with severe visual acuity loss among untreated eyes. Presence of any of these risk factors was considered an indicator for treatment with PRP.
Risks of Treatment: PRP was associated with mild loss of vision soon after treatment, particuarly in eyes with pre-existing macular oedema. However, long-term benefits outweighed the risk of visual loss.
Conclusion:
The DRS was a seminal clinical trial, as it provided a firm evidence-base for the effectiveness of PRP in reducing the progression of proliferative diabetic retinopathy and severe sight loss in high-risk diabetic retinopathy eyes.
References:
Please note: the reference shown at the top above is for the first report (Report 1) of the DRS, which consisted of 14 reports in total. The other published reports from the DRS study are as follows:
Diabetic Retinopathy Study Research Group. Photocoagulation treatment of proliferative diabetic retinopathy: the second report of Diabetic Retinopathy Study findings. Ophthalmology 1978; 85:82-106.
Diabetic Retinopathy Study Research Group. Four risk factors for severe visual loss in diabetic retinopathy: the third report from te Diabeteic Retinopathy Study. Arch Ophthalmol 1979; 97:654-655.
Diabetic Retinopathy Study Research Group. Photocoagulation treatment of proliferative diabetic retinopathy: a short report of long range results. DRS report number four. Proceedings of the 10th Congress of the International Diabetes Federation. Amsterdam: Excerpta Medica; 1979:789-794.
Diabetic Retinopathy Study Research Group. Photocoagulation treatment of proliferative diabetic retinopathy: relationship of dverse treatment effects to retinopathy severity. DRS study report no. 5. Dev Ophthalmol 1981; 2:248-261.
Diabetic Retinopathy Study Research Group. Diabetic Retinopathy Study report number 6 design, methods and baseline results. Invest Ophthalmol Vis Sci 1981; 21:149-208.
Diabetic Retinopathy Study Research Group. DRS report number 7: a modification of the Airlie House classification of diabetic retinopathy. Invest Ophthalmol Vis Sci 1981; 21:210-226.
Diabetic Retinopathy Study Research Group. Photocoagulation treatment of proliferative diabetic retinopathy. Clinical application of DRS findings. DRS report number 8. Ophthalmology 1981; 88:583-600.
Knatterud GL. Mortality experience in the DRS. Isr J Med Sci 1983; 19; 424-428.
Ederer F, Podgor MJ, the Diabetic Retinopathy Study Research Group. Assessing possible late treatment effects in stopping a clinical trial early: a case study. DRS report no 9. Control Clin Trials 1984; 5:373-381.
Rand LI, Prud'homme GJ, Ederer F et al. Factors influencing the develpoment of visual loss in advanced diabetic retinopathy: DRS report no. 10. Invest Ophthalmol Vis Sci 1985; 26:983-991.
Kaufman SC, Ferris FL, Swartz M et al. Intraocular pressure following panretinal photocoagulation for diabetic retinopathy. DRS report no. 11. Arch Ophthalmol 1987; 105:807-809
Ferris FL, Podgor MJ, Davis MD et al. Macular edema in DRS patients. DRS report number 12. Ophthalmology 1987;94:754-760
Kaufman SC, Ferris FL et al. Factors associated with visual outcome after photocoagulation for diabetic retinopathy: DRS study report no 13. invest Ophthalmol Vis Sci 1989;30:23-28.
Diabetic Retinopathy Study Research Group. Indications for photocoagulation treatment of diabetic retionpahty: DRS report no. 14. in Ophthalmol Clin 1987; 27:239-253.
Diabetic Retinopathy Study (DRS)
Study Details
Introduction:
The Diabetic Retinopathy Study (DRS) was the first major initiative of the National Eye Institute. It was a multi-centre, randomized clinical trial designed to evaluate the safety and efficacy of panretinal photocoagulation (PRP) in reducing the risk of vision loss and blindness in patients with advanced diabetic retinopathy. 1758 patients were enrolled between 1972 and 1975.
Eligibility:
Patients were eligible if they had best corrected visual acuity of 20/100 or better in each eye and the presence of proliferative diabetic retinopathy in at least one eye or severe nonproliferative retinopathy in both eyes. They could not have had prior treatment with photocoagulation or pituitary ablation, and both eyes had to be suitable for photocoagulation. All eligible patients were younger than 70 years, and the examining physician assessed the outlook for survival and availability for 5 years of followup to be good.
Methodology:
One eye of each patient was randomly assigned to immediate photocoagulation and the other to followup without treatment, regardless of the course followed by either eye. The eye chosen for photocoagulation was randomly assigned to either of two treatment techniques, one using an argon laser and the other a xenon arc photocoagulator. Patients were followed at 4-month intervals according to a protocol that provided for measurement of best corrected visual acuity.
Treatment was usually completed in one or two sittings and included scatter (panretinal) photocoagulation extending to or beyond the vortex vein ampulae. The argon treatment technique specified 800 to 1,600, 500-micron scatter burns of 0.1 second duration and direct treatment of new vessels whether on or within one disc diameter of the optic disc (NVD) or outside this area (NVE). Focal treatment was also applied to microaneurysms or other lesions thought to be causing macular edema. Followup treatment was applied as needed at 4-month intervals. The xenon technique was similar, but scatter burns were fewer in number, generally of longer duration, and stronger, and direct treatment was applied only to NVE on the surface of the retina.
Results:
Primary Outcome:
Secondary Outcomes:
Conclusion:
The DRS was a seminal clinical trial, as it provided a firm evidence-base for the effectiveness of PRP in reducing the progression of proliferative diabetic retinopathy and severe sight loss in high-risk diabetic retinopathy eyes.
References:
Please note: the reference shown at the top above is for the first report (Report 1) of the DRS, which consisted of 14 reports in total. The other published reports from the DRS study are as follows:
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