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Effects of conventional argon panretinal laser photocoagulation on retinal nerve fibre layer and driving visual fields in diabetic retinopathy
Author(s) -
MUQIT MMK,
GHANCHI FD,
WAKELY L,
HENSON DB,
STANGA PE
Publication year - 2009
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2009.4217.x
Subject(s) - medicine , ophthalmology , retinal , diabetic retinopathy , nerve fibre layer , panretinal photocoagulation , visual field , retina , optics , diabetes mellitus , physics , endocrinology
Purpose To determine the effects of argon green panretinal laser photocoagulation (AG‐PRP) on retinal nerve fibre layer thickness (RNFLT), threshold visual fields (VF), and Estermann full binocular VF over time. Methods Prospective, pilot clinical study of patients with newly‐diagnosed proliferative diabetic retinopathy (PDR). Time‐Domain optical coherence tomography (TD‐OCT) of optic nerve head and 24‐2 SITA‐Fast Humphrey/Estermann VF (HVF, EVF) recorded at baseline, 10 weeks and 6 months post‐laser. Quantitative field analysis of central 10º, 24º, and binocular VF. Results 10 eyes underwent uncomplicated multiple‐session 100ms AG‐PRP using 2000 burns, 400μm spot, and mean power 136 mW (SD 39.3). TD‐OCT detected and quantified an increase in mean RNFLT at 10 weeks (+8 μm; p<0.05) and progressive thinning at 6 months (‐4 μm; p<0.05) compared to baseline. Mean threshold sensitivities, 10° and 24°, improved at both time‐points in the majority (9/10 and 8/10) of patients. Masked grading of EVFs showed no significant change with treatment. Conclusion This pilot study demonstrates that conventional AG‐PRP may increase the RNFL in the short‐term, presumably related to laser‐induced axonal injury, with progressive thinning of RNFL in the longer‐term. The sensitivity of both 10° and 24° VFs improved significantly following AG‐PRP, and this central functional improvement may be due to a reduction in oedema folowing AG‐PRP. Binocular standard driving VFs performed within 6 months of AG‐PRP may actually reflect pre‐existing VF abnormalities due to severe retinal ischaemia or non‐viable retina at presentation, rather than direct functional loss from laser.