Comparison of Snellen and interferometer visual acuity in an aging noncataractous population

Using standard clinical procedures we have compared visual acuity (VA) estimates made with a hand-held white light interferometer to those obtained with a Snellen acuity chart. Fifty noncataractous patients with a mean age of 45 years (SD = 18) were tested. Snellen and interferometric acuity measures were obtained with and without refractive correction. On average, aided Snellen VA's were better (decimal acuity = 0.98) than the unaided interferometric VA's (decimal acuity = 0.67). Although we found a statistically significant p less than 0.01) correlation between unaided interferometric and aided Snellen VA's, the correlation was poor (r = 0.36). This poor correlation may account for the often observed failure to estimate postoperative aided Snellen VA with preoperative interferometric VA in cataract patients.