The Classification of Disability Glare and the Effect of Age

We investigated the influence of age on the debilitating effect of glare for glare sources applied to the task or to the eye. Low-contrast logMAR letters were presented on a computer monitor, and the visual performance of 66 adults (23 to 66 yrs.) was measured under three conditions: no glare, ocular disability glare and task disability glare. A significant decline in visual performance with age was found in each condition. Factoring out the decline due to age alone (the ‘no-glare’ condition), a large, significant (p < 0.001) effect of age on ocular disability glare (a decline of 0.089 logMAR units per decade) remained, as did a very small effect on task disability glare (a decline of 0.026 logMAR units per decade, p = 0.051). These results show that different mechanisms are responsible for the impact of the two types of disability glare, indicating the need to differentiate between them in their classification.