Wavefront Analysis in Post-LASIK Eyes

Abstract

We read with great interest the recent article by Chalita et al regarding wavefront analysis in post-LASIK eyes with the LADARWave measurement device (Alcon, Fort Worth, TX).1Chalita M.R. Chavala S. Xu M. Krueger R.R. Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topography.Ophthalmology. 2004; 111: 447-453Abstract Full Text Full Text PDF PubMed Scopus (187) Google ScholarThe authors correlated visual symptoms to higher order aberrations obtained from wavefront maps using 3 different pupil sizes (5 mm, 7 mm, and scotopic). In “Materials and Methods,” the authors state that “the patients were submitted to complete ophthalmologic examinations, including manifest refraction in a dark room, cycloplegic refraction, computerized corneal topography … before dilatation, and dilated wavefront measurement.” They did not mention whether the pupil size was actually measured, how it was measured, or what kind of device was used for the measurement. Pupil size is considered a relevant factor affecting the measurement of optical aberration. With the LADARWave device, a measurement session has to be performed on the patients with pupil dilation between 7 and 11 mm. The pupil diameter could differ at each wavefront measurement for the same patient. Therefore, our question is whether the pupils were actually measured at 5 mm or 7 mm or sampled from the wavefront analysis at these pupil sizes. In other words, does how the authors created different pupil size groups and how they measured higher order aberrations depend on pupil size? Clarifying these points would be important in understanding this study. We read with great interest the recent article by Chalita et al regarding wavefront analysis in post-LASIK eyes with the LADARWave measurement device (Alcon, Fort Worth, TX).1Chalita M.R. Chavala S. Xu M. Krueger R.R. Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topography.Ophthalmology. 2004; 111: 447-453Abstract Full Text Full Text PDF PubMed Scopus (187) Google Scholar The authors correlated visual symptoms to higher order aberrations obtained from wavefront maps using 3 different pupil sizes (5 mm, 7 mm, and scotopic). In “Materials and Methods,” the authors state that “the patients were submitted to complete ophthalmologic examinations, including manifest refraction in a dark room, cycloplegic refraction, computerized corneal topography … before dilatation, and dilated wavefront measurement.” They did not mention whether the pupil size was actually measured, how it was measured, or what kind of device was used for the measurement. Pupil size is considered a relevant factor affecting the measurement of optical aberration. With the LADARWave device, a measurement session has to be performed on the patients with pupil dilation between 7 and 11 mm. The pupil diameter could differ at each wavefront measurement for the same patient. Therefore, our question is whether the pupils were actually measured at 5 mm or 7 mm or sampled from the wavefront analysis at these pupil sizes. In other words, does how the authors created different pupil size groups and how they measured higher order aberrations depend on pupil size? Clarifying these points would be important in understanding this study. Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topographyOphthalmologyVol. 111Issue 3PreviewTo evaluate the information assessed with the LADARWave wavefront measurement device and correlate it with visual symptoms, refraction, and corneal topography in previously LASIK-treated eyes. Full-Text PDF Wavefront Analysis in Post-LASIK Eyes: Author replyOphthalmologyVol. 112Issue 6PreviewWe appreciate Jin and Merkley’s comments, and their interest in seeking clarification about the pupil size differences we reported. The first question they appropriately raise is what device, if any, was used in measuring scotopic pupil size. Our answer confirms their suspicion, as we used a Colvard pupilometer (Oasis, Glendora, CA) to document the pupil size under dark room conditions and then used this valve to set the aberrometer to the specified pupil size for analysis. Because a pharmacologically dilated pupil is always of greater diameter than when physiologically dilated, aberrometry was performed after pharmacological dilation, so that a range of pupil diameters could be selected and set within the LADARWave device. Full-Text PDF