Viswanathan, Ananth Chitur; (2001) Visual function in glaucoma: Improving the assessment of computerised visual fields. Doctoral thesis (M.D), UCL (University College London).

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Abstract

Glaucoma is a leading cause of world blindness. In order to ascertain whether the disease is progressive or stable, glaucoma patients' visual function is monitored at regular intervals by testing the visual field using the technique of automated perimetry. The numerical data obtained, relating to the spatial co-ordinates of the test locations and light sensitivities at those locations, are amenable to sophisticated statistical analysis. This thesis centres on a method for detecting glaucomatous change in serial visual fields known as pointwise linear regression: univariate linear regression of sensitivity on time is performed for each test location in the visual field. This method has been incorporated into a software package, PROGRESSOR. Results indicate that PROGRESSOR is superior to previously accepted glaucoma change probability software in the early detection of glaucomatous visual deterioration. A higher level of concordance between expert observers in the assessment of glaucomatous visual progression is found when PROGRESSOR, rather than standard clinical methods, is used. The optimum frequency of visual field testing is investigated: reducing the frequency of examinations from 3 per year to 1 per year results in failure to detect over half of the deteriorating test locations. A strong association is found between patient perception of visual disability and objectively measured damage and deterioration in glaucomatous visual fields even in mild to moderate glaucoma. Image processing techniques have previously been used to increase the reproducibility and predictability of automated visual field tests. These techniques are incorporated into PROGRESSOR. Results presented in this thesis indicate that these benefits are obtained without delayed detection of visual field progression. The PROGRESSOR software shows great potential in the detection and quantification of glaucomatous visual field deterioration. It promises to be an important part of the management of glaucoma patients in the future.

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