Sir,
Case report
The Early Treatment of Diabetic Retinopathy Study (ETDRS) showed that laser photocoagulation reduced moderate visual loss (MVL) in patients with clinically significant diabetic macular oedema (CSME).1 The recent UK National Diabetic Retinopathy Laser Audit showed some effect with laser treatment, otherwise there is little data from UK units.2, 3, 4 We reviewed the outcome of patients treated for CSME in the Southampton Eye Unit.
All the patients referred with CSME in 1998 from our screening service were included. The Snellen visual acuity (converted to LogMAR),5 number of treatments, and fluorescein angiographies performed were recorded. The patients were followed for 3 years, and the proportion of patients with MVL at 1, 2, and 3 years was compared to ETDRS data (Figure 1).
Graph showing incidence of MVL.
One-hundred and thirty eight eyes from 106 patients with untreated diabetic maculopathy received laser treatment. The average visual acuity at referral was between 6/7.5 and 6/9. Only four eyes developed proliferative diabetic retinopathy during the period audited. Ten eyes were excluded for coexisting ocular pathology; seven eyes underwent cataract surgery, two had vitrectomies, and one eye amblyopia. MVL occurred in 5.1% of patients at 1 year, 8.2% at 2 years, and 14.7% at 3 years. There was no statistically significant difference in MVL between the ETDRS immediate treatment arm and our patients (P=0.11). No patient underwent fluorescein angiography.
Comment
The recent UK audit of diabetic maculopathy treatment found that 9.2% of patients doubled their visual angle by 9 months.2, 3 Our outcomes were more positive, possibly as a result of these being newly diagnosed cases. This was achieved without fluorescein angiography. There is little evidence that patients having fluorescein angiograms have better acuity outcomes than individuals treated on clinical grounds alone. A randomized controlled trial to conclusively demonstrate visual benefit would be prohibitively expensive.6 Could other noninvasive methods of assessing macular morphology such as optical coherence tomography be used to target laser treatments in the early stages of the disease?
At present, UK audit standards for diabetic maculopathy treatment require assessment of waiting times and access to treatment but not of the visual outcome. This audit demonstrates that measurement of visual outcomes can be achieved, and are essential for the assessment of retinal services, from screening to treatment.
References
Early Treatment of Diabetic Retinopathy Study Group. Study 1. Photocoagulation for diabetic macular oedema. Arch Ophthalmol 1985; 103: 1796–1806.
Bailey CC, Sparrow JM, Grey RH, Cheng H . The National Diabetic Retinopathy Laser Treatment Audit. I. Maculopathy. Eye 1998; 12(Part 1): 69–76.
Bailey CC, Sparrow JM, Grey RH, Cheng H, The National Diabetic Retinopathy Laser Treatment Audit. II. Proliferative retinopathy. Eye 1998; 12(Part 1): 77–84.
Bailey CC, Sparrow JM, Grey RH, Cheng H, The National Diabetic Retinopathy Laser Treatment Audit III. Clinical outcomes. Eye 1999; 13(Part 2): 151–159.
Bourne RR, Rosser DA, Sukudom P, Dineen B, Laidlaw DA, Johnson GJ et al. Evaluating a new logMAR chart designed to improve visual acuity assessment in population-based surveys. Eye 2003; 17(6): 754–758.
Kylstra JA, Brown JC, Jaffe GJ, Cox TA, Gallemore R, Greven CM et al. The importance of fluorescein angiography in planning laser treatment of diabetic macular edema. Ophthalmology 1999; 106(11): 2068–2073.
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Sinclair, N., Booth, A., Clover, A. et al. Argon laser photocoagulation for diabetic macular oedema. Eye 20, 1471–1472 (2006). https://doi.org/10.1038/sj.eye.6702361
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DOI: https://doi.org/10.1038/sj.eye.6702361
