Association between subjective Visual Function and both Low Contrast Visual Acuity and Contrast Sensitivity in Cataract

There has been significant interest over the past 20 years in assessing visual function in the presence of cataract. Measures for objectively quantifying the degree of visual loss as the cataract advances could be used to decide on the point where surgical intervention is needed.

It has been found that 2 patterns of visual loss occur in cataract: one where contrast sensitivity loss occurs at high spatial frequency and is frequency dependent, and another where there is additional contrast sensitivity loss at low and mid spatial frequencies which was constant.  High contrast visual acuity test charts are frequently used as a measure of visual performance. However, visual acuity does not distinguish between these two types of loss since visual acuity may be lowered in both cases. 

Furthermore, with the second type of visual loss a patient may present with good visual acuity but complain of poor vision.

Glare tests assess visual function by usually recording a loss in visual performance for a standard test under glare and no glare conditions.  These tests have shown that the introduction of a glare source has the greatest effect on contrast sensitivity in cortical and posterior subcapsular cataracts.

Attempts have been made to correlate subjective perception of visual function determined by questionnaire with objective measures of vision.  However, there is little conclusive data about the association between subjective and objective function stratified into different cataract morphologies.

This study assessed the strength of association between different cataract morphologies graded using the LOCSIII system and visual function.

Ms Hakim-Banan was awarded an MSc following successful completion of this project.