European Journal of Ophthalmology / Vol. 6 / no. 1, 1996/ pp. 59-62 Alteration of visual function in impaired glucose tolerance S. KARADENIZ " N. KIR 2, M. T. YILMAZ 1.3, E. ONGOR 2, N. DIN99AG 13, D. BA$AR 2, K. AKAR9A Y 2, I. SATMAN 1.3, A.S. DEVRIM 1.3 1 Institute for Experimental Medicine 2 Department of Ophthalmology, Faculty of Medicine 3 Division of Diabetes, Dept. of Internal Medicine, Faculty of Medicine, Istanbul University, Istanbul - Turkey ABSTRACT: People with impaired glucose tolerance are considered to be prone to diabetes. To evaluate their visual function we investigated colour vision with the Farnsworth-Munsell 100 Hue test and contrast sensitivity with Arden's grating cards in people with impaired glu- cose tolerance (lGT), people with normal glucose tolerance (NGT) and others with type /I diabetes (NIDDM). Eyes with low vision or any anterior or posterior segment abnormalities were excluded. Contrast sensitivity and color vision differed significantly between the groups (p<0.01). It thus appears that patients with IGT but without clinical diabetes could be fol- lowed up to see whether these alterations have any predictive value for the development of diabetes and diabetic retinopathy. (Eur J Ophthalmol 1996; 6: 59-62) KEY WORDS: Impaired glucose tolerance, Contrast sensitivity, Colour vision INTRODUCTION Visual function involves a complex array of percep- tual mechanisms. These include visual acuity, con- trast sensitivity (CS), color vision (CV), form and mo- tion perception and stereopsis. CS and CV are af- fected to various extents in diabetes; psychophysical visual function tests like CV and CS are interesting in that detection of early visual dysfunction may predict later development of retinopathy. CS and CV are re- duced in many diabetics without retinopathy although they have a visual acuity of 20/20 (1). Impaired glucose tolerance (IGT) may be one stage in the natural history of diabetes, because people with IGT appear to be at a higher risk than the general population for the development of diabetes and its complications (2, 3). When retested 5-10 years after being initially as- certained as IGT, about one-third of subjects have oral glucose tolerance test (OGTT) results that would qualify them as diabetic (3). In the present study we investigated CS and CV in people with IGT, according to WHO criteria, who are at an increased risk of developing diabetes and its complications, and compared the results with people with type II diabetes (NIDDM) without retinopathy and with people with normal glucose tolerance (NGT). METHODS This study included 43 patients with IGT and 39 pa- tients with NIDDM who are followed up regularly in the Division of Diabetes of the Istanbul Faculty of Medicine, and 33 subjects with NGT who had an OGTT in the clinic. Their characteristics are shown in Table I. There were no differences between the chronolog- ical age and number of eyes in each group (p>0.05). The mean follow-up period in the IGT group was 30.6±42.3 months. The mean duration of diabetes in the NIDDM group was 13.1 ±8 years. IGT diagnosis, based on WHO criteria, is suggest- --- --- -------- © by Wichtig Editore, 1996 1120-6721/059-04 $02.00/0