Abstract
Purpose::
To determine if cataract extraction and placement of a square edged optic decreases glare and improves functional vision as measured objectively by Brightness Acuity Testing (BAT) pre-operatively and one month post-operatively.
Methods::
Thirty-one male patients at the Nashville Veterans Administration Hospital who met criteria and desired cataract surgery were studied for the effect of cataract extraction with intraocular lens implantation upon BAT results. The criteria consisted of a best corrected visual acuity (VA) of 20/50 or worse, or a BAT of 20/50 or worse on medium luminance. Best corrected VA was assessed with BAT on low, medium, and high luminance levels in a standard 10 lux examination lane pre-operatively and then again one month following standard cataract extraction by phacoemulsification with implantation of a mono-focal Acrysof SN60AT posterior chamber intraocular lens. The surgeries were performed by 4 surgeons. One-month data were available for 17 of 31 patients (55%). VA at one month postoperatively was 20/25 or better in 79% of the patients.
Results::
There was a statistically significant improvement in best corrected Va as measured by BAT at all three luminance levels one month following cataract surgery. Va improved from logMAR 0.416 to 0.109 at the low luminance setting, from 0.533 to 0.121 at the medium luminance setting, and from 0.714 to 0.167 at the high luminance setting (all with p<0.00001). In five patients with ocular pathology in addition to cataract (macular degeneration, epiretinal membrane, pattern dystrophy, retinal atrophy, corneal guttata) the difference in preoperative and postoperative VA by BAT was not statistically significant (p=0.13, 0.25, and 0.31 for low, medium and high luminance respectively). The difference in VA among patients with otherwise normal eyes maintained statistical significance (p<0.00001) at all luminance levels.
Conclusions::
Our results objectively support the improvement of functional vision with cataract extraction as measured with BAT. Contrary to reports of increased glare with square-edged optics, we found a statistically significant decrease in glare at all luminance levels with BAT testing after implantation of SN60AT optics. BAT appears to be an effective evaluation tool of visual disability in the pre-surgical work-up of patients with cataracts but may not be as useful in the setting of other ocular pathology.
Keywords: cataract • intraocular lens • visual acuity