Certain other important signs need to be carefully elicited in a patient with cataracts. The pupil reaction is a particularly useful index of retinal function and it is not impaired by the densest of cataracts. A poor reaction might lead one to suspect age-related macular degeneration or chronic glaucoma, but a brisk pupil with a mature cataract might be described as a "surgeon's delight" because it indicates the likelihood of restoring good vision to a blind eye. The function of the peripheral retina can be usefully assessed by performing the light projection test. This entails seating the patient in a darkened room, covering one eye, and asking him or her to indicate, by pointing, the source of light from a torch positioned at different points in the peripheral field. Checking the pupil and the light projection test take a brief moment to perform and are by far the most important tests of retinal function when the retina cannot be seen directly. A number of other more sophisticated tests are available, for example ultrasonography, electroretinography and measurement of the visually evoked potential. Sometimes, at least an area of the peripheral retina can be seen when the pupils have been dilated, and all cataract patients should be examined in this way before one embarks on more complex tests. A search for the signs of cataract thus involves a full routine eye examination, including a measurement of the best spectacle correction.
Was this article helpful?