Contrast sensitivity and visual recovery time in diabetic patients treated with panretinal photocoagulation.

PURPOSE: To study patients treated with panretinal photocoagulation regarding contrast sensitivity and visual recovery time after exposure to glare.
METHODS: To compare contrast sensitivity and visual recovery-time after exposure to glare in eyes (n=20) from 20 type 1 diabetic patients treated with panretinal photocoagulation for proliferative retinopathy with eyes (n= 19) from 19 un-treated type 1 diabetic patients. Contrast sensitivity was tested with a low contrast acuity chart, before and during exposure to either a uniform background illumination or a spotlight. Visual recovery time was defined as the time required to regain baseline visual acuity during light exposure.
RESULTS: Contrast thresholds values were higher in eyes treated with panretinal photocoagulation compared to un-treated eyes before illumination 4.2 +/- 1.2% vs. 3.1 +/- 1.7% (p=0.006), during background illumination 5.8 +/- 5.1% vs. 3.9 +/- 4.8% (p=0.001), and during spotlight exposure 5.6 +/- 2.2% vs. 3.2 +/- 1.8% (p<0.001). Furthermore, recovery time was longer both during background illumination, 20; 5-50 sec vs. 2; 2-80 sec. (md;range), (p<0.001) and during spotlight illumination 27; 5-70 sec vs. 2;1-60 sec. (md;range) (p<0.001).
CONCLUSION: Eyes treated with panretinal photocoagulation had higher contrast threshold levels at baseline and during glare, as well as a prolonged visual recovery time compared to un-treated eyes with mild background retinopathy.