నైరూప్య

Visual acuity-DYOP® versus Snellen acuity charts: A review.

Peter Gordon

To compare the visual acuity of pre and post cataract surgery's patients using a Snellen acuity chart and DYOP acuity chart as to differences in resolution acuity versus recognition acuity.

Fifty-nine patients (105 eyes) with senile cataracts aged 40 years or older, and with no other ocular pathologies, were evaluated as to visual acuity for pre and post cataract surgery using the Snellen acuity and DYOP acuity charts.

Cataracts were nuclear in 50 eyes, nuclear and posterior sub capsular in 24 eyes, nuclear and cortical in 23 eyes, nuclear, cortical and posterior sub capsular in 4 eyes as well as nuclear, anterior and posterior sub cortical in 2 eyes, pre cataract surgery. The mean VA measured at pre cataract surgery was significantly overestimated with Snellen (OD: 0.64 ± 0.15, OS: 0.69 ± 0.23 decimal units) versus a DYOP (OD: 0.53 ± 0.25, OS: 0.55 ± 0.24 decimal units), for both eyes (OD: p=0.01, OS: p=0.01). The mean VA measured at post cataract surgery was also significantly overestimated with Snellen (OD: 0.88 ± 0.22, OS: 0.85 ± 0.20 decimal units) versus a DYOP (OD: 0.72 ± 0.22, OS: 0.72 ± 0.23 decimal units), for both eyes (OD: p=0.00, OS: p=0.01).

Visual acuity measurements for pre and post cataract surgery were different with a Snellen acuity chart and a DYOP acuity chart in that the DYOP test was a more precise indicator of acuity resolution. The apparent strength of the DYOP acuity assessment is that it utilizes Dynamic Resolution Acuity to prevent the 0.25 diopter overestimation of visual acuity inherent in the Static Recognition Acuity of the Snellen test.