Comparison of Hartmann Shack Aberrometer and OPD Scan in Postkeratoplasty Wavefront Analysis of Interrupted Suturing versus Combined Interrupted and Continuous Suturing Techniques

Abstract

Abstract: : Purpose:To compare the wavefront aberrations after penetrating keratoplasty using a proprietary Hartmann Shack (HS) aberrometer versus an OPD Scan (Nidek Co, Japan), and to determine if a combined interrupted and continuous suturing technique reduces higher order aberrations post–operatively when compared to an interrupted–only suturing technique. Methods:. Eyes were divided into two groups: eyes sutured using a combined interrupted and continuous suturing technique (Group 1), and eyes sutured using an interrupted–only suturing technique (Group 2). Whole eye wavefront aberrations were measured at both 3mm and 6mm pupils using an HS aberrometer, and at a 6mm pupil using an OPD–Scan. Data was collected at both one month and two month post–operative visits. Individual 3^rd, 4^th, 5^th, and 6^th order, as well as total higher order aberrations were calculated for all eyes using both wavefront devices. Results: Data collection on a total of five eyes demonstrated that the HS aberrometer generated higher values at 6mm versus 3mm pupil size. In Group 1, one month HS total higher order RMS was 8.355 at 6mm and 1.794 at 3mm. The Group 2 HS total higher order RMS at one month was not measurable at 6mm, and 0.5755 at 3mm. OPD RMS error was lower than HS at 6mm pupil size, with one month data revealing a Group 1 total RMS of 2.573 and Group 2 total RMS of 1.174. At two months, the HS RMS error for Group 1 was 167.7 at 6mm and 1.274 at 3mm. The OPD total RMS at two months for Group 1 was 2.476. An association in Group 1 eyes between best corrected visual acuity and wavefront aberrations was not clearly delineated. Although manifest refraction did not correlate with the total RMS using the HS aberrometer in Group 1 eyes, despite a range of spherical equivalents from –0.50 to –9.50 diopters, and an astigmatism range of +0.50 to +6.00 diopters, greater astigmatism was associated with a greater total RMS using the OPD. Over all groups, time points, and devices, 3^rd and 4^th order aberrations were consistently greater than 5^th and 6^th order aberrations. Conclusions:HS higher order aberrations were greater at 6mm pupil size, likely secondary to graft edge effect, than the OPD in these eyes. No clear difference in wavefront aberrations was noted between the two different suturing techniques. Visual acuity was not related to wavefront aberrations, while the OPD showed greater RMS error with increasing astigmatism. The overall most common whole eye wavefront aberrations seen in early post–keratoplasty eyes are 3^rd and 4^th order aberrations.

Keywords: cornea: clinical science • optical properties • refractive surgery: other technologies