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Assessment of Colour Vision as a Screening Test for Sight Threatening Diabetic Retinopathy before Loss of Vision

journal contribution
posted on 2023-06-08, 05:33 authored by G L Ong, L G Ripley, R S B Newsom, A G Casswell
Aim: To assess the effects of sight threatening diabetic retinopathy (STDR) on colour vision and to evaluate automated tritan contrast threshold (TCT) testing for STDR screening before significant visual loss. Method: Patients were recruited from a hospital based photographic screening clinic. All subjects underwent best corrected Snellen visual acuity (BCVA) and those with 20/30 vision or worse were excluded. Automated TCT was performed with a computer controlled, cathode ray tube based technique. The system produced a series of sinusoidal, standardised equiluminant chromatic gratings along a tritan confusion axis. Grading of diabetic retinopathy was made by one of the team of experienced ophthalmic registrars (SpR) using slit lamp biomicroscopy and a 78D lens; HbA1c and urine albumin were also tested. Results: Patients with STDR had significantly worse TCT despite normal BCVA (p<0.0001). TCT yielded a sensitivity of 100% for detecting diabetic maculopathy and 94% for STDR with a specificity of 95%. Logistic regression analyses showed that TCT (p<0.001) and HbA1c (p<0.05) correlated significantly with the presence of STDR but duration of diabetes, urine albumin counts, and BCVA failed to show any significant correlation. No associations between TCT and duration of disease, TCT and HbA1c, and TCT and urine albumin counts were found. Conclusion: Tritan colour vision deficiency was observed in patients with STDR despite their normal BCVA. These results indicate that automated TCT assessment is an effective and clinically viable technique for detecting STDR, particularly diabetic maculopathy, before visual loss.


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  • Published


British Journal of Ophthalmology







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  • Engineering and Design Publications


A major problem for ophthalmologists is diabetic retinopathy and it has been specifically identified as a disease for which there is need of screening. This publication is one of a series which shows that not only does (tritan) colour-vision deficit identify the existence of sight-threatening retinopathy but, indeed, it can predict its onset by as much as a year in advance of the symptomatic morphological changes to the retina. Currently grant applications are being made from the Sussex Eye Hospital (Lead Surgeon Mr AG Casswell) with the aim of establishing colour-vision screening as a vital element of primary care.

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