Sensitivity Function to Contrast in Type 1 Diabetics (IDDM) without Signs ofDiabetic Retinopathy

Overview

The objective of the work was to assess whether in patients with IDDM withoutsigns 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 asa result of the persistence of IDDM or the level of its long-term compensationinvestigated by means of glycated haemoglobin (HbA1c). CS was examined by thestatic method using a VCTS 6500 table from a distance of 208 and 420 cm whichcovered the spatial frequencies from 1.15 to 27.25 c/st. Moreover the authorsassessed the best correctable central visual acuity on Snellen´s optotypes, theophthalmoscopic finding on the fundus with a colour photograph, fluoresceinangiography and the HbA1c serum level. A group of 49 patients with IDDM wasdivided into two age groups: A(under 35 years), B (35 years and above). A markeddecline ofthe CS function occurs in all spatial frequencies in both age groups. Oncomparison of the persistence of IDDM in group B no significant difference wasfound in CS, while in group A statistical significance was revealed in spatialfrequencies 4 and 27,25 c/st. On comparison of the CS function in diabetics witha normal and pathological HbA1c level it was found that long-term hyperglycae-mia has not a marked effect on visual functions.Conclusion: The decline of CS in patients with IDDM without signs of diabeticretinopathy 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 methodsuitable for screening of early affections of the eyes in IDDM

Key words:
diabetes mellitus (IDDM), contrast sensitivity, glycated haemoglobin