Application of a Revised Tissue Saving Protocol for Combined Topography-Guided Photorefractive Keratectomy and Cross-Linking in a Cohort Having Pellucid Marginal Degeneration.

Purpose: To evaluate the efficiency, safety, and stability of a revised tissue-saving treatment protocol in a cohort having pellucid marginal degeneration (PMD). Methods: A retrospective cohort study was conducted on patients with PMD and no previous treatments. A revised protocol of topo-guided photorefractive keratectomy to be followed by customized phototherapeutic keratectomy and then corneal crosslinking was evaluated by comparing the pre and postoperative outcomes regarding visual (subjective refraction) and topographic (using data from Sirius CSO topography software) outcomes. Results: There were both statistically significant and clinically relevant improvements in the postoperative parameters, where each of the unaided and corrected visual acuity, spherical equivalent, refractive cylinder, K readings, topographic cylinder, inferior minus superior difference at the 2- and 4- mm diameters, coma aberration, and higher order aberrations were significantly better postoperatively (all p values were less than 0.01, except for maximum k readings where the p-value was 0.017). The safety and efficacy indices for the surgical procedure were remarkably high (1.53 ± 0.70 and 0.90 ± 0.32, respectively). Conclusion: Our proposed tissue-saving protocol (which showed satisfactory results in keratoconus cases according to a previously published article by our research team) has proven its successful outcomes (both topographically and visually) in cases of PMD, which is a rare ectatic entity with guarded prognosis using the available conventional ectasia treatment modalities.

Novel Technique to Improve the Efficacy of Corneal Cross Linking in Cases of Post LASIK Ectasia.

Purpose: The aim of the present study was to validate the use of a novel technique that can improve the efficacy of corneal cross-linking (CXL) in cases with post LASIK ectasia. Methods: This is a retrospective, comparative study that was conducted on patients who sought medical advice at Ain Shams University Hospitals and Maadi Eye Subspeciality Center, Cairo, Egypt. It included two groups of patients with post LASIK ectasia. Group 1 included patients who performed our proposed protocol (topo-guided PRK, followed by customized phototherapeutic keratectomy "PTK" to transmit the laser treatment to the corneal stroma, then CXL). For group 2, accelerated CXL was performed. Subjective refraction and relevant topographic/tomographic parameters (Sirius topographer) compared between the two groups. Recorded follow-ups included the 2 to 3-month follow-up visit and the last visit (mean ± SD of 17.2 months ± 10.2). Results: Patients of group 1 (22 eyes of 22 patients) experienced significant improvements in most of the evaluated parameters at the 2- to 3-month follow-up visit and showed stability of the ectatic condition at the last follow-up visit, whereas patients of group 2 (10 eyes of 10 patients) showed stability of their ectatic condition at the 2- to 3-month follow-up visit, and one patient developed ectasia progression at the last follow-up visit. Conclusion: The present study validates the use of our novel protocol in cases having post LASIK ectasia with proven efficacy, safety, and stability, providing regularization for the corneal surface while simultaneously avoiding the unnecessary loss of cross-linking effect within the LASIK flap that no longer shares in the corneal biomechanical strength.

Comparison Between Pulsed and Continuous Accelerated Corneal Cross-Linking Protocols.

Purpose: To compare between two accelerated corneal cross-linking (A-CXL) protocols in the management of keratoconus (KC) as regard to the extent of corneal treatment. Methods: This retrospective, comparative study included patients having mild to moderate, progressive KC. The study population was divided into two groups; group 1 enrolled 103 eyes of 62 patients who received pulsed light A-CXL (pl-CXL) at a power of 30 mW/cm2 with an irradiation time of 4 minutes, while group 2 comprised 87 eyes of 51 patients who received continuous light A-CXL (cl-CXL) at a power of 12 mW/cm2 with an irradiation time of 10 minutes. Recordings of the central and peripheral demarcation line depths (DD), and the maximum (DDmax) and minimum (DDmin) DD, using anterior segment optical coherence tomography, were compared between the two studied groups one month after the treatment protocol. Treatment stability was also evaluated pre and postoperatively (one year following surgery) by comparing the refractive and keratometric outcomes in both groups. Results: The differences between the preoperative corneal thickness (minimum and central) and the epithelial thickness measurements between both groups were not statistically significant. Although group 1 had slightly larger central DD (223.4 ± 62.3 um), DDmax (240.4 ± 61.8 um), and DDmin (201 ± 54 um) than those of group 2 (221.8 ± 37 um, 229.1 ± 38.4 um, and 212 ± 37.2 um, respectively), the differences between both groups' measurements were not statistically significant. Also, the two groups showed statistically insignificant differences regarding the subjective refraction and the average and maximum keratometry pre and postoperatively, denoting visual, refractive, and keratometric stability in both groups. Conclusion: Longer duration cl-CXL seems to be as effective as pl-CXL regarding both postoperative stability and the extent of corneal tissue penetration by the ultraviolet treatment.

Endothelial cell loss rate after penetrating keratoplasty: optical versus therapeutic grafts.

Background: This study aimed to compare the rate of endothelial cell loss (ECL) after penetrating keratoplasty (PKP) for optical versus therapeutic grafts at 3-, 6-, and 12-month postoperatively. Furthermore, the study aimed to investigate postoperative graft viability and the rate of graft rejection during the first year of follow-up for both indications. Methods: This was a prospective, observational, comparative study that included patients who sought medical advice at the cornea outpatient clinic of Ain Shams University Hospitals, Cairo, Egypt. The study recruited 60 patients: group 1 included 30 transplanted corneas of 30 patients who underwent optical PKP for various indications, while group 2 included 30 transplanted corneas of 30 patients who underwent therapeutic PKP for unhealed, resistant infectious keratitis. Specular microscopy was performed for all patients at the 3-, 6-, and 12-month follow-up visits using Nidek CEM-530 specular microscopy. Postoperative clinical examinations were performed at the same follow-up visits to detect graft rejection. Results: There were no statistically significant differences between the groups concerning the postoperative timing of graft clarity or the rate of ECL at 3- and 6-months postoperatively; however, the rate of ECL was significantly greater in group 2 than in group 1 at 12-months postoperatively (P = 0.03), although the difference was small from a clinical point of view. Moreover, there was no statistically significant difference between the groups in terms of the graft rejection rate. Conclusions: Therapeutic PKP results were comparable to optical PKP with respect to graft viability, the rate of ECL, and the rate of graft rejection 1 year after grafting.

Relation of Corneal Astigmatism with Various Corneal Image Quality Parameters in a Large Cohort of Naïve Corneas.

PURPOSE: To investigate the relationship between corneal astigmatism and corneal image quality parameters (i.e., root mean square [RMS] of some major corneal higher order aberrations [HOAs] "namely RMS of coma aberrations, RMS of trefoil aberrations, and RMS of spherical aberration [RMS-SA]" and Strehl ratio [SR] of point spread function [PSF]) by using the Sirius topographer (CSO Italia, Florence, Italy). PATIENTS AND METHODS: This cross-sectional study used the Sirius topographer to evaluate the naïve corneas of right eyes (n = 1,356). The study included three groups which were based on the mean anterior corneal astigmatism value (group 1, <1 D; group 2, 1-2 D; and group 3, >2 D). RESULTS: The corneal astigmatism showed statistically significant (yet narrow clinical) differences among the groups regarding all the examined parameters (P<0.001), except for the RMS-SA (which was statistically insignificant among the three groups). Correlation coefficients were weak between the corneal astigmatism and HOAs (correlation coefficient "r" not reaching 0.2 with any of the evaluated HOAs). CONCLUSION: Significant differences existed among the astigmatic groups regarding corneal HOAs, but the mean values were very close. The deduced relations between corneal astigmatism and corneal image quality parameters had limited clinical relevance. Thus, the corneal astigmatism should be evaluated separately from corneal image quality parameters, either when deciding between refractive correction modalities (customized versus optimized ablation techniques) or when evaluating corneal image quality of a naïve cornea.

Single suture customized loop for large iridodialysis repair.

Managing large iridodialysis that may occur during phacoemulsification is challenging. I describe how a procedure to reposit a prolapsed iris while the anterior chamber is markedly inflated by a current of infusion fluid may inadvertently lead to large iridodialysis, and discuss how to avoid such a complication. I describe a fast and efficient technique for managing large iridodialysis both immediately, once it occurs, or as a secondary maneuver. My technique involved fixing the iris periphery back to its root at the anterior chamber angle using 10-0 polypropylene suture with two straight needles introduced directly through the cornea at distant points, and an insulin syringe as a guide track to a point 1.5 mm from the limbus at the base of a triangular scleral flap that was designed to be centered on the area of iridodialysis. I confirmed the simplicity, efficacy, and safety of my technique through a 1-year follow-up period.