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A. Tatham, A. MacFarlane; Visual Outcome Following Laser Photocoagulation for Diabetic Retinopathy. Results in Clinical Practice Versus Results in Clinical Trials . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1011.
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To compare outcome following laser photocoagulation for diabetic retinopathy in a general hospital with outcome in the Diabetic Retinopathy Study (DRS) and Early Treatment of Diabetic Retinopathy Study (ETDRS). Landmark trials have shown that laser photocoagulation can reduce visual loss in patients with diabetic retinopathy by 50–60%. Such studies have had major implications for clinical practice however there are differences between the studied samples and the general population. Clinical practice is not governed by the same inclusion criteria as well structured clinical trials. Many of our patients are over 70 years old or may have poor visual acuity or coexisting ocular pathology that would have excluded them from the ETDRS or DRS. We investigated rates of moderate and severe visual loss among diabetic patients following laser photocoagulation in a general hospital.
Retrospective case–note analysis of 100 consecutive patients attending for laser photocoagulation (panretinal, grid or focal macular treatment) from January 1999 to April 1999. Individuals were treated according to methods used in the DRS and ETDRS. Visual acuity was recorded at yearly intervals for 5 years following treatment. Interventions that may have influenced visual acuity (e.g. further laser photocoagulation, cataract surgery) were noted. Severe visual loss was defined as worse than 5/200 visual acuity at two or more consecutive visits (as defined by the DRS). Moderate visual loss was defined according to the ETDRS as at least doubling of the visual angle.
Data for 75/100 patients was retrieved. The 5–year incidence of moderate visual loss was 17.3% (13/75 patients). The 5–year incidence of severe visual loss was 5.3% (4/75 patients). The DRS found rates of severe visual loss at 4 years were 4%, 7% or 20% in treated patients with severe NPDR, mild PDR and high–risk PDR respectively. Moderate visual loss for treated patients with clinically significant macular oedema in the ETDRS ranged from 14% to 13% at 3 years.
Similar rates of severe and moderate visual loss occurred in our sample as compared to the ETDRS and DRS. This is despite many of our patients having characteristics that may have excluded them from the landmark trials. Since the ETDRS and DRS, the importance of blood pressure, cholesterol and glycemic control has become more apparent. The DCCT and UK–PDS have led to increased emphasis on strict control of risk factors. With improvements in medical control and new treatment techniques such as intravitreal triamcinolone the incidence of visual loss should be further reduced.
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