Effects of conventional argon panretinal laser photocoagulation on retinal nerve fibre layer and driving visual fields in diabetic retinopathy

Aims To determine the effects of argon green panretinal laser photocoagulation on retinal nerve fibre layer thickness, threshold visual fields, and Estermann full-binocular visual fields over time in diabetic retinopathy. Method Prospective, pilot clinical study. Time-domain optical coherence tomography (TD-OCT) of the optic nerve head and 24-2 SITA-Fast Humphrey/Estermann visual fields (HVF, EVFs) recorded at baseline, 10 weeks, and 6 months post laser. Quantitative field analysis of central 10 degrees, 24 degrees, and binocular visual fields. Results A total of 10 eye samples were subjected to uncomplicated multiple-session 100 ms panretinal laser using 2000 burns, 300-mu m spot, and mean power of 136 mW (SD +/- 39.3). TD-OCT detected and quantified an increase in mean retinal nerve fibre layer thickness at 10 weeks (+8 mu m; P<0.05) and progressive thinning at 6 months (-4 mu m; P<0.05) compared with baseline. Mean threshold sensitivities, and 10 degrees and 24 degrees HVF improved at both time points in the majority (9 of 10 and 8 of 10) of patients. EVFs showed no significant change with treatment. Conclusions This pilot study shows that conventional argon laser panretinal photocoagulation may increase the retinal nerve fibre layer thickness in the short term, presumably related to laser-induced axonal injury, with progressive thinning of nerve fibre layer over the long term. The 101 and 241 visual fields improved significantly after laser with no adverse effects on the UK standard driving fields. Eye (2010) 24, 1136-1142; doi:10.1038/eye.2009.308; published online 18 December 2009