[Reduction of retinal light sensitivity in diabetic patients]

Visual field loss in diabetic patients has received comparatively little attention. The aim of the present study was firstly to assess the influence of type 2 diabetes mellitus on retinal light sensitivity in diabetic patients without signs of diabetic retinopathy (DR) and secondly to assess the association between visual field loss and the severity of nonproliferative DR.

151 eyes of 151 diabetic patients with type 2 diabetes mellitus and 30 eyes of 30 healthy volunteers were included in our study. Visual acuity was 0.7 or better with correction. DR staging was based on a modified Airlie-House classification. The eyes were divided into four groups: no DR, mild NPDR, moderate NPDR and severe NPDR. Ophthalmic examination was normal in all diabetic patients, except for DR. All participants underwent visual field testing with the C 30-2 program of the Humphrey field analyser.

Retinal light sensitivity was significantly reduced before clinically detectable DR with MD (mean deviation) p values less than 10% in 14.3% (8 of 56 eyes). Patients with mild NPDR had a significant reduction of retinal sensitivity in 21.1% (8 of 38 eyes), with moderate NPDR in 45.8% (11 of 24 eyes) and with severe NPDR in 63.6% (21 of 33 eyes). PSD (pattern standard deviation) p values less than 10% were observed in 7.1% (4 of 56 eyes) in patients without DR, with mild DR in 31.6% (12 of 38 eyes), with moderate in 50% (12 of 24 eyes) and in patients with severe DR in 60.1% (20 of 33 eyes). Using the analytical STATPAC program of the Humphrey Field Analyzer, the reduction of retinal sensitivity was significant between controls and diabetic patients without DR and between individual groups of diabetic patients.

The severity of visual field loss was greater in advanced stages of DR. In diabetic patients with severe DR, a significant reduction of retinal light sensitivity was observed in more than 60%. In diabetic patients without DR, despite no evident capillary closure on fluorescein angiography--similar as in the control group, where retinal sensitivity was normal in all cases--a significant reduction of retinal sensitivity was found in more than 14.3%.