Relationship between contrast sensitivity and metabolic control in diabetics with and without retinopathy

Abstract

Contrast sensitivity was studied in diabetic adolescents and young adults with and without retinopathy in order to evaluate their central vision, to analyze the relationship of metabolic control to the presence and severity of retinopathy, and to re-evaluate the response to this test after a significant improvement in metabolic control. Twenty adolescent and young adult diabetics without retinopathy and 40 diabetics with retinopathy of varying degree were enrolled in the study; 20 healthy age and sex-matched subjects served as controls. Contrast sensitivity was assessed with a CSV-1000 contrast testing instrument, testing for four spatial frequencies, 3, 6, 12 and 18 cycles per degree (cpd). Diabetics with no retinopathy showed a weak but significant difference at 18 cpd compared with controls (P = 0.04), while diabetics with background retinopathy showed a significant reduction of contrast sensitivity at 12 and 18 cpd when compared with controls (P < 0.001). In patients with preproliferative/proliferative retinopathy a highly significant reduction of contrast sensitivity at all frequencies was found compared with controls. Furthermore, these patients had a significantly lower mean contrast sensitivity than patients without retinopathy. The patients were re-evaluated after a significant amelioration of metabolic control. An improvement in contrast sensitivity was found in diabetics without retinopathy and with background retinopathy, while there was no change observed in diabetics with severe retinopathy. These results show that diabetic adolescents and young adults with and without signs of retinopathy observed by fluorescein angiography have a reduced contrast sensitivity, which is more severe in patients with preproliferative/proliferative retinopathy. A significant amelioration of metabolic control is associated with an improvement of contrast sensitivity in all patients with the exception of those patients who had signs of preproliferative/proliferative retinopathy observed by fluorescein angiography. In summary, this longitudinal study provides the first evidence that reduced contrast sensitivity is reversible in diabetics with or without background retinopathy only.

Mesopic foveal contrast sensitivity is impaired in diabetic patients without retinopathy

“…Different factors were tested in correlation with the CS function. The same CSV-1000 testing instrument showed a positive relationship between metabolic control and CS in young IDDM patients with and without retinopathy [7]. In type 2 diabetic patients, contrast sensitivity deficits, determined by stationary grating, were positively correlated with the patient's age, blood pressure, and nephropathy [8], and in young IDDM (type 1), the patient's microalbuminuria was also found to be associated with reduced CS [9].…”

“…Various techniques have been adopted to measure CS, and most of them reported a significant difference between diabetic and normal eyes. CS was tested in insulin-dependent diabetic patients (IDDM) and in noninsulin-dependent diabetic patients (NIDDM), both young and old [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Functional Retinal Impairment in Type 1 Diabetic Patients without any Signs of Retinopathy

“…A sensitivity loss of phototransduction for both rods and cones, causing reduction in dark adaptation and loss of colour determination and contrast sensitivity, and an altered waveform response for both amacrine and bipolar cells, reflecting a diffused alteration in neuronal synaptic transmission, have been described [5,12,13,14,15,16,17,18]. …”

“…Electrophysiological studies in animal models of diabetes and in human subjects had shown an impairment of the innermost retinal layers [5,11,12] and of amacrine cells [12,13,14] as well as an impairment of the short-, mid- and long-wavelength cone components in different stages of the pathology [15,16,17,18]. …”

A multifocal electroretinogram model predicting the development of diabetic retinopathy

“…Contrast sensitivity is impaired (Di Leo, et al, 1992;Hyvarinen, et al, 1983;Liska and Dostalek, 1999;Sokol, et al, 1985;Stavrou and Wood, 2003;Verrotti, et al, 1998), as is contrast sensitivity for motion detection (Kawasaki, et al, 1986). Recovery from glare (retinal photo stress) is delayed and dark-adapted thresholds are elevated (Greenstein, et al, 1993;Parisi, et al, 1994;Spafford and Lovasik, 1986).…”