Introducing a Revised Tissue Saving Protocol for Combined Topography-Guided Photorefractive Keratectomy and Cross-Linking in Keratoconic Corneas.

PURPOSE: The aim of this study was to introduce a revised tissue-saving technique for combined topography-guided photorefractive keratectomy (PRK) and cross-linking for keratoconus (KC) treatment and to evaluate its efficacy, safety, and stability. METHODS: This retrospective, noncontrolled study was performed at Maadi Eye Subspecialty Center and Eye Care Center, Cairo, Egypt. The technique was performed on virgin keratoconic corneas with 3 different morphological patterns of ectasia. It involves performing topography-guided PRK before epithelial removal, followed by customized phototherapeutic keratectomy (PTK) that is tailored to each cornea after studying the treatment profile on the laser treatment screen. The electronic medical records were explored for preoperative and postoperative data, including subjective refraction and topographic data (using Sirius topographer). RESULTS: The study was conducted on 123 eyes of 93 patients with a mean age of 27.98 years ±6.06. The follow-up ranged from 6 to 36 months (mean ± SD of 16.2 months ±10.4). The results showed statistically nonsignificant differences among the 3 ectasia subgroups in treatment spherical equivalent, treatment maximum depth, thickness of removed epithelium, and thinnest residual stromal bed. There were statistically significant differences in almost all values between the preoperative and postoperative data, with significant postoperative patients' improvement ( P value <0.001). The subgroups' results were almost the same as the whole cohort's results. The safety and efficacy indices of the performed procedure showed remarkably high values (1.48 ± 0.21 and 0.87 ± 0.40, respectively). CONCLUSIONS: This revised protocol for KC management maximally preserves stromal tissue with proven efficacy, safety, and stability.

Contralateral eye study of refractive, topographic and aberrometric outcomes after femtosecond assisted MyoRing implantation and DALK for management of keratoconus.

AIM: To evaluate the efficacy of femtosecond laser assisted MyoRing intrastromal corneal implant and deep anterior lamellar keratoplasty (DALK) for management of moderate to advanced keratoconus regarding the degree of changes in visual acuity, refraction, corneal asphericity and aberrations. METHODS: A prospective non comparative interventional case study was conducted in Ophthalmology Department, Ain Shams University Hospital in the period from January 2015 to February 2017. The study included 30 eyes of moderate to advanced keratoconus. MyoRing was implanted in one eye (Group I) and DALK operation was performed in the contralateral eye of the same patient (Group II). Preoperative and 6mo post-operative uncorrected visual acuity (UCVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), corneal and refractive astigmatisms, keratometry and Q-value using topography images were acquired. Quality of vision was assessed in all eyes including total corneal, anterior corneal high order aberrations analysis at 5 mm pupil size and the Strehl ratio of point spread function (PSF) as an objective measure of glare. RESULTS: Mean postoperative UCVA, CDVA, SE, refractive astigmatism, keratometry readings and asphericity were statistically improved compared to preoperative parameters in both groups (P<0.05). Significant reduction of all corneal aberrations following both techniques (P<0.05) was achieved except mean trefoil and mean PSF in Group I (P>0.05). Postoperative corneal aberrations were significantly lower in Group II compared to Group I. A statistically significant negative correlation was found in Group I between the mean change in CDVA (logMAR) and the mean preoperative and mean postoperative total corneal aberrations root mean square (RMS; r=-0.78, P=0.04). Also a statistically significant negative correlation was found between mean preoperative coma RMS and mean post PSF (r=-0.86, P=0.01). In Group II, there was a statistically significant positive correlation between mean change in CDVA (logMAR) and mean change in Kmax (r=0.87, P=0.01) and between mean change in refractive cylinder and mean postoperative PSF (r=0.76, P=0.05). CONCLUSION: Femtosecond laser assisted MyoRing and DALK are effective in improving visual acuities, refraction, corneal asphericity and aberrations. MyoRing reduced spherical error more than the corneal cylinder. Post operative homogenous corneal surface and good image quality were achieved following both techniques compared to the preoperative state. However, DALK results in better image quality and lower corneal aberrations.

Comparative study of 3 intracorneal implant types to manage central keratoconus.

PURPOSE: To compare the visual acuity, refraction, corneal topography, and corneal asphericity of intrastromal corneal implantation of Keratacx 160-degree 2 symmetrical ring segment, the Keratacx 320-degree near-total ring, and the Myoring continuous intracorneal ring (ICR) in central keratoconus. SETTING: Ophthalmology Department, Ain Shams University, Cairo, Egypt. DESIGN: Prospective case series. METHODS: Surgeries were performed using a femtosecond laser for tunnel creation for the 160-degree 2-segment device (Group 1) and the 320-degree near-total ring (Group 2), and for pocket creation for the ICR (Group 3). The preoperative and 6-month postoperative uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical equivalent (SE), corneal and refractive astigmatism, keratometry (K) readings, and Q value using topography images were acquired. RESULTS: The study included 73 eyes. No statistically significant differences were found in the preoperative parameters between groups (P > .05). The postoperative UDVA, CDVA, SE, corneal and refractive astigmatisms, K readings, and Q value were statistically better than the preoperative parameters in all study groups (P < .01). A statistically significant increase in the median UDVA and CDVA occurred in Group 2 compared with Group 1 (P < .01). Groups 2 and 3 had a more effective reduction in SE (P < .01). No statistically significant difference was found in the postoperative changes in the corneal and refractive cylinders, mean and maximum K readings, and corneal asphericity between the study groups (P > .05). CONCLUSIONS: All devices were effective in improving UDVA, CDVA, refraction, K readings, and corneal asphericity. The 320-degree segment and ICR improved UDVA and SE more than the 2-segment device.

Contralateral assessment of sub-Bowman keratomileusis (SBK) microkeratome suction duration on laser-assisted in-situ keratomileusis (LASIK) flap characteristics.

PURPOSE: To describe the effect of prolonging the standard suction duration during laser-assisted in-situ keratomileusis (LASIK) and its effect on flap thickness and hinge length using sub-Bowman keratomileusis (SBK) microkeratome. METHODS: Fifty-six eyes (28 patients) were included and divided into 2 groups; Group-A: eyes with flatter corneas (36 eyes, 18 patients) and mean keratometric readings ranging from 40.13 to 43.71 diopters (D). Group-B: eyes with steeper corneas (20 eyes, 10 patients) with mean keratometric readings ranging from 43.85 to 46.72 D. One-Use-Plus SBK microkeratome was used for flap creation. For right eyes, flap was created immediately once suction was built up. In left eyes, the surgeon waited for 10 s after suction was built up before flap creation. Flap hinge length and flap thickness were measured using surgical caliper and ultrasonic pachymetry, respectively. RESULTS: Statistically significant differences were observed in corneal flap hinge size between right eyes versus left eyes, with a mean of 3.98 ± 0.48 vs. 3.78 ± 0.55 mm (p < 0.001). Mean flap thickness in both eyes did not prove to be statistically significantly different with either surgical technique (90.2 ± 1.68 vs. 90.07 ± 1.44 µm, p = 0.8). Sub-group analysis of Group-A vs. Group-B revealed hinge sizes that were significantly larger in steeper corneas (p < 0.01 and p < 0.05, respectively). However, flap thickness in both groups was unaffected by surgical procedure (p = 0.5). CONCLUSIONS: Increasing suction duration increases flap hinge length and stabilizes the flap, especially in steeper corneas.