Investigating the topographic effect of epithelium in myopic eyes with subtle topographic preoperative abnormalities.

PURPOSE: To explore the topographic impact of the epithelium in Keratoconus Suspected (KCS) and in "Normal" Placido classified corneas. SETTING: Rothschild Foundation, Paris, France. DESIGN: Prospective interventional case series. METHODS: Anterior corneal specular Placido topography using OPD-Scan® II (NIDEK, Gammagori, Japan) was performed in 97 eyes of 67 patients undergoing PRK for myopia, before and after epithelium removal. The differences in axial keratometry, asphericity and astigmatism were computed. RESULTS: After epithelial peeling, some Placido-normal classified corneas became KCS. Therefore, we have subdivided this group into two groups: one of normal classified corneas which stayed normal after epithelium removal (Group NN), and one of corneas that became KCS classified (Group NK).The mean difference in axial mean keratometry in the third central millimeter rings was +0.50 ± 0.24 D, 0.69 ± 0.31 D and 0.49 ± 0.35 D and the mean difference in the magnitude of epithelial induced astigmatism in the first central millimetre ring was 0.37 D x 89° (positive cylinder), 0.54 D 86° and 0.52 D 86° respectively in Group NN, NK and KK (KCS corneas that stayed KCS). These differences were significant (p< 0.0001). Preoperative keratometry was the only predictive factor differentiating Group NN from NK (p<0.001). CONCLUSIONS: The epithelial layer tended to reduce the magnitude of the Bowman layer's astigmatism, prolateness and keratometry, more importantly in Group NK. In KK group we found a similar trend as in normal eyes (Group NN). The epithelium would be able to mask Bowman layer's irregularities until a certain degree of severity.

High hyperopic LASIK with reduction of corneal prolateness to control induced spherical aberration.

PURPOSE: To evaluate visual outcomes of high hyperopic LASIK, using corneal aspherization to control the induced spherical aberration. SETTING: Fondation Ophtalmologique Adolphe de Rothschild. DESIGN: Prospective interventional case series. METHODS: Prospective interventional study of consecutive high hyperopes (≥+3D of Spherical Equivalent SE) undergoing LASIK with the WaveLight FS200 femtosecond and EX500 excimer laser platform. An aspheric ablation profile (planned change in corneal asphericity ΔQ = +0.2) was delivered using the Custom-Q nomogram (Alcon Laboratories, Inc., Fort Worth, TX) on an optical zone of ≥ 6.5mm centered near the corneal vertex. Uncorrected and best-corrected distance visual acuity (UDVA-BDVA), as well as changes in SE, corneal asphericity (ΔQ) and Higher order aberrations (HOAs), were analyzed preoperatively and on day1, 1, 3, 6, and 12 months. RESULTS: 117 eyes of 63 patients, (mean age of 30.1 ± 5.6 years), were included. Preoperatively and at 12 months postoperatively, the mean SE was 5.1 ± 1.1 D and 0.00 ± 0.7 D, respectively. 88% of eyes achieved 0 Log Mar or better UDVA at 12 months. One month after surgery, there was a statistically significant induction of positive spherical aberration decreasing progressively and significantly until the last visit (Preop SA4 = 0.09 ± 0.11 µm, Day 1 SA4 = 0.30 ± 0.32 µm, 12 Months SA4 = 0.08 ± 0.21 µm, p=0.056). Two eyes needed enhancement at 12 months. CONCLUSION: LASIK for high levels of hyperopia showed good outcomes mainly due to aspheric-customized ablation profile with a change of ΔQ = +0.2 in corneal asphericity.

Anatomical and Visual Outcomes after LASIK Performed in Myopic Eyes with the WaveLight® Refractive Suite (Alcon® Laboratories Inc., USA).

PURPOSE: To evaluate changes in corneal anatomy and quality of vision following LASIK refractive surgery for mild to high myopia using the WaveLight® Refractive Suite (Alcon® Laboratories Inc., USA). Setting. Rothschild Foundation, Paris, France. DESIGN: Prospective interventional case series. METHODS: We examined 60 myopic eyes (average SE -4.5 D, from -9.3 to -0.75 D) of 30 patients from 21.3 to 38.7 years old. Pachymetry, keratometry, Q factor, corneal aberrations, visual acuity (VA), contrast sensitivity, dry eye assessment, and quality of vision were measured preoperatively, one day (D1), and 1, 3, and 6 months postoperatively. RESULTS: 6 months postoperatively, keratometry became flatter, and the Q factor became more oblate (from -0.18 ± 0.08 to +0.19 ± 0.06). Pachymetry decreased by 117.9 ± 62.2 µm at D1 and increased by 37.87 ± 32.6 µm between D1 and M6. Refraction was emmetropic at D1 and remained stable thereafter. Six months after surgery, VA was slightly but nonsignificantly improved (<0.05 log MAR), whereas contrast sensitivity remained unchanged. Quality of vision was not affected by surgery and was more related to dry eye symptoms than to corneal HOAs (r 2 = 0.49; p < 0.001 vs. r 2 = 0.03; p < 0.001). CONCLUSIONS: LASIK surgery for moderate to high myopia, performed with the WaveLight® Refractive Suite, showed good postoperative outcomes, with demonstrated safety, predictability, efficiency, and stability. This is probably due to well-controlled spherical aberration and the use of large optical zones. Besides, we can assume that the patients' quality of vision depends more on the postoperative dry eye disease generated by the laser than on the induced HOAs.

Assessing Repeatability of Pupillometric Measurements in the Eyes of Refractive Surgery Candidates Using Infrared Pupillometer.

PURPOSE: To assess the repeatability of measuring pupil dynamics using an infrared pupillometer. METHODS: A total of 124 eyes of 124 patients scheduled for corneal laser refractive surgery were separated into myopic and hyperopic groups and further subdivided based on high or low levels of astigmatism. Measurements were taken using dynamic pupillometry (Topolyzer Vario; Alcon Laboratories, Inc., Sinking Spring, PA). Main outcome measures were pupil diameter size, the distance between the pupil center and the keratoscopic axis, and the spatial shift of the pupil center. Repeatability of measurements was assessed from test-retest repeatability (2.77 Sw), coefficient of variation, and intraclass correlation coefficient (ICC). RESULTS: The 2.77 Sw of all measured parameters was lower than 0.36 and 0.44 mm for myopic and hyperopic eyes, respectively. ICCs of the pupil diameter measurements were higher than 0.963 and 0.926 in myopic and hyperopic eyes, respectively. ICCs of the distance between the pupil center and the corneal vertex along the x-axis were higher than 0.934 and 0.994 in myopic and hyperopic eyes, respectively. Along the y-axis, ICCs of this distance were higher than 0.417 in myopic eyes and higher than 0.504 in hyperopic eyes. The pupil center shift measurement ICCs were lower than 0.482 and 0.526 for myopic and hyperopic eyes, respectively. CONCLUSIONS: In all groups, the Topolyzer Vario showed excellent repeatability when measuring pupil dynamic parameters except when measuring pupil center shift and distance between the pupil center and the corneal vertex along the vertical axis. [J Refract Surg. 2017;33(8):552-557.].

Topography of the corneal epithelium and Bowman layer in low to moderately myopic eyes.

PURPOSE: To compare the epithelium (air-tear film) and Bowman layer's specular topographies in patients having low to moderate myopia corrected by photorefractive keratectomy (PRK). SETTING: Rothschild Foundation, Paris, France. DESIGN: Prospective interventional case series. METHODS: Anterior corneal specular Placido topography using the OPD-Scan II Placido-based topographer was performed in eyes of patients having PRK for myopia before and after epithelial removal. The differences in axial keratometry (K), asphericity (Q value), astigmatism magnitude (toricity), and axis were computed in the 1st, 3rd, and 5th central corneal millimeter zones. RESULTS: The study comprised 51 patients (90 eyes). The mean difference in axial mean K was 0.56 diopter (D) ± 0.26 (SD), 0.56 ± 0.27 D, and 0.56 ± 0.24 D in the 1st, 3rd, and 5th central millimeter rings, respectively. The mean difference in the magnitude of epithelium-induced astigmatism was 0.42 ± 0.43 D × 90, 0.41 ± 1.60 D × 78, and 0.02 ± 1.82 D × 83 (positive cylinder) in the 1st, 3rd, and 5th central millimeter rings, respectively. Corneal astigmatism shifted toward an increased with-the-rule orientation after epithelial removal. The mean difference in asphericity (over the central 6.0 mm zone) was -0.07 ± 0.21. These differences were significant (P < .0001) and independent of age, sex, central pachymetry, and spherical equivalent. CONCLUSIONS: In low to moderately myopic eyes, the topography of Bowman layer was significantly steeper than that of the epithelium. The epithelial layer tended to reduce the magnitude of Bowman layer's astigmatism and prolateness. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.