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Abstract

The primary purpose of this study was to determine if subjects at risk of developing diabetes showed significant loss of colour vision and to identify and grade risk factors for diabetes based on early changes in chromatic sensitivity and rod and cone mediated vision.

Previous studies of diabetic patients without retinopathy had found significant loss of chromatic sensitivity to varying degrees, affecting both Yellow/Blue (YB) and Red/Green (RG) chromatic mechanisms. However, it is unclear whether subjects at risk of developing diabetes also show loss of colour vision, rapid flicker sensitivity and spatial vision when compared to age-matched controls.

For this study, three subject groups were recruited: G1 (the ‘normal’ subject group, n = 40, who had no risk factors and no history of eye disease); G2 (the ‘high-risk’ subject group, n = 150, with three or more risk factors for diabetes); and G3 (diagnosed with diabetes, n = 23). RG and YB vision, thresholds for rod- and cone-mediated vision and Visual acuity (VA), functional contrast sensitivity (FCS) were assessed by using Colour assessment and diagnosis (CAD), Flicker sensitivity and Acuity plus tests respectively to assess the overall quality of the spectral, spatial and temporal properties of subject’s vision. In addition, each of the risk factors for diabetes was examined in G2 to establish its effects on RG and YB colour thresholds and the loss of rod and cone sensitivity by using multiple linear regression analysis.

The results show that G3 subjects demonstrated the highest loss in colour vision thresholds, rod- and cone-mediated flicker sensitivity and spatial vision when compared to G1 and G2 subjects. Surprisingly, G2 subjects (who did not meet the clinical criteria for diabetes) also had significantly higher RG and YB thresholds and higher rod- and cone-mediated thresholds than G1. Loss of VA and FCS under photopic conditions was also seen. In G2 patients, age above 45 years was a risk factor for RG and YB colour loss. Lack of exercise, age above 45 years and hypertension were risk factors for loss of rod and cone sensitivity.

From this study, loss of both colour vision and rod- and cone-mediated sensitivity are evident and worse in both G2 and G3 subjects when compared to G1. The most significant risk factors in G2 according to this study are advancing age, high blood pressure and lack of exercise. These findings suggest that both RG and YB colour vision thresholds and rod- and cone-mediated rapid flicker sensitivity tests capture best the loss of functional vision in G2 and may therefore be considered an important risk factor in pre-diabetic screening.

Publication Type:	Thesis (Doctoral)
Subjects:	R Medicine > RE Ophthalmology
Departments:	Doctoral Theses School of Health & Psychological Sciences > School of Health & Psychological Sciences Doctoral Theses School of Health & Psychological Sciences > Optometry & Visual Sciences

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