Glare testing after dilation is unreliable in patients with cataracts

Researchers examined 54 patients with no history of cataract surgery for pupil size, visual acuity, and glare testing with the Brightness Acuity Tester (BAT) before and after pupil dilation. These results were then correlated with the patients' degree of cataract using the Lens Opacification Classification System III by an independent observer.

When dilated, about half the patients lost one or more lines of vision during BAT testing. However, glare testing after dilation can be done reliably by adjusting for the change in visual acuity after dilation. With this method undilated BAT results were predicted within one line of accuracy in 81.5 percent of patients and within two lines in 96.3 percent. They also found that patients with posterior subcapsular cataracts are most affected by inaccurate BAT results from dilation.