This comment regards the article "Potential Acuity Pinhole: A Simple Method to Measure Potential Visual Acuity in Patients with Cataract, Comparison to Potential Acuity Meter" appearing in the July issue of Ophthalmology by Melki et al. ~ We wish to point out a misleading statement in the discussion section concerning the comparison of their results in 49 eyes selected with cataract and no coexisting eye disease to our study of consecutive cases undergoing cataract surgery of which 21 of 100 had comorbid disease. We quote, "It [refers to the Illuminated Near Card] 2 predicted distance acuity to within 2 lines in 98% and 53% of eyes with preoperative distance acuity of 20/100 or better and 20/200 or worse, respectively. These figures are very similar to our [refers to potential acuity pinhole]' results (100% and 56%)." It is scientifically incorrect to compare a series of eyes without comorbid disease to a series including comorbid disease. In eyes without comorbid disease, as in the series reported by Melki et al, overestimation can occur only because of inaccurate refraction and cannot be due to the potential vision tester since the visual potential is 20/20 in normal eyes. They reported overestimation in only 8% of eyes and all by one line or less. This simply means that they refracted well. However, in eyes with comorbid disease, overestimation of postoperative acuity is the most feared consequence of potential vision testing because of false hopes given to the patient and the generation of unnecessary surgery. In our series, the postoperative acuity was predicted to within one line or less in all 21 eyes with comorbid disease, and this ability to accurately predict vision in eyes with comorbid disease is what determines the value of a potential vision tester. In an article3 reviewing the literature on potential vision testing from 1975 through 199O, the conclusion was that reported studies (including results on the Potential Acuity Meter) did not provide enough evidence to support the use of potential vision testing to detect poor surgical outcomes. To date, the Illuminated Near Card (INC) is the only potential vision tester shown to accurately predict vision in eyes with cataract and comorbid disease.

The potential acuity pinhole) test uses the three optical principles described in 19964 for testing potential vision at near with the INC, namely (1) equivalent visual angle to Snellen letters, (2) pinhole aperture, and (3) bright illumination. In testing with the INC, these three principles are controlled by supplying means of maintaining the correct reading distance during testing, by correcting for the refractive error and adding 2.5 diopters for near (underestimation may occur if near correction is not used when testing high myopes and hyeropes), and by standardizing and controlling the illumination level. In distinction to the INC, the testing protocol for the potential acuity pinhole test disregards these controls of the variables. We warn those using the potential acuity pinhole test to be aware of the possibility of overestimating acuity in eyes with comorbid disease because some eyes with maculopathy5 require as much as 100 times the illumination level of normal eyes to reach maximum acuity, and maximum acuity may be far greater than best distance acuity. Too bright of a light source can result in overestimation. Who knows what the luminance levels are as the Finoff transilluminator tip is moved to titrate the illumination to the patient's response as used in the potential acuity pinhole test?

ALBERT J. HOFELDT, MD

SAMTR MELKI, MD, PHD