[Contrast sensitivity in type I diabetics without symptoms of diabetic retinopathy]

The objective of the work was to assess whether in patients with IDDM without signs of diabetic retinopathy changes in the sensitivity function to contrast (CS) develop as compared with a group of healthy subjects matched for age but also as a result of the persistence of IDDM or the level of its long-term compensation investigated by means of glycated haemoglobin (HbA1c). CS was examined by the static method using a VCTS 6500 table from a distance of 208 and 420 cm which covered the spatial frequencies from 1.15 to 27.25 c/st. Moreover the authors assessed the best correctable central visual acuity on Snellen's optotypes, the ophthalmoscopic finding on the fundus with a colour photograph, fluorescein angiography and the HbA1c serum level. A group of 49 patients with IDDM was divided into two age groups: A(under 35 years), B (35 years and above). A marked decline of the CS function occurs in all spatial frequencies in both age groups. On comparison of the persistence of IDDM in group B no significant difference was found in CS, while in group A statistical significance was revealed in spatial frequencies 4 and 27.25 c/st. On comparison of the CS function in diabetics with a normal and pathological HbA1c level it was found that long-term hyperglycaemia has not a marked effect on visual functions.

The decline of CS in patients with IDDM without signs of diabetic retinopathy is influenced in particular by the patient's age, in junior patients also by the persistence of IDDM. Examination of the CS is a simple non-invasive method suitable for screening of early affections of the eyes in IDDM.