Intrastromal corneal ring segment implantation in paracentral keratoconus with perpendicular topographic astigmatism and comatic axis

Purpose: To evaluate the outcomes of implanting intrastromal corneal ring segment (ICRS) using two different strategies in a specific paracentral keratoconus phenotype. Methods: Eighty-nine eyes with paracentral keratoconus with perpendicular topographic astigmatism and comatic axes were evaluated before and after implanting a 150° arc-length ICRS. Patients were divided into two groups according to the axis where the ICRS was implanted: Group I: comatic axis and Group II: flat topographic axis. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refractive errors, and root mean square (RMS) for coma-like aberration were recorded. The postoperative follow-up was 1 year. Results: Mean UDVA (logMAR) changed from 0.49 ± 0.37 preoperatively to 0.30 ± 0.32 6 months afterwards ( p < 0.001) in the group I and from 0.53 ± 0.34 to 0.37 ± 0.35 ( p < 0.001), in the group II. Mean CDVA in group I changed from 0.11 ± 0.18 preoperatively to 0.06 ± 0.14 6 months after surgery ( p < 0.001). In group II the improvement did not reach statistical significance (from 0.09 ± 0.10 to 0.07 ± 0.09; p = 0.06). No eyes lost lines of CDVA in group I. Eight eyes (15.7%) lost lines of CDVA in group II. The spherical equivalent decreased after surgery in both groups ( p < 0.001). The RMS for corneal coma-like aberration only decreased in the group I ( p < 0.001). Conclusion: Both strategies provided safe and effective visual and refractive outcomes in the specific keratoconus phenotype analyzed. The orthopedic strategy provided better visual outcomes than the refractive one.

Systematic review and meta-analysis of femtosecond laser–enabled keratoplasty versus conventional penetrating keratoplasty

Purpose: The aim of this meta-analysis is to compare femtosecond laser–enabled keratoplasty with conventional penetrating keratoplasty regarding postoperative astigmatism, visual functions, graft rejection, graft failure, and complications. Methods: Eligible studies were retrieved from five mainstream electronic databases, including PubMed, Embase, Ovid MEDLINE, Cochrane Library, and ClinicalTrial.gov. Postoperative topographic astigmatism was set as the primary outcome, and best-corrected visual acuity, spherical equivalent, endothelial cell density, graft rejection, graft failure, and complications were chosen as the secondary outcomes. Standard mean difference and risk ratio were the size effects for continuous data and binomial data, respectively. The data were pooled through either the random-effects model or the fixed-effects model based on data heterogeneity. Moreover, subgroup analyses were conducted when the heterogeneity occurred distinctly (I2 > 50%). Results: A total of seven comparative studies were included. The pooled standard mean difference (−0.32, 95% confidence interval: −0.74 to 0.10) showed that femtosecond laser–enabled keratoplasty was not superior over conventional penetrating keratoplasty to decrease postoperative topographic astigmatism (p = 0.14). However, best-corrected visual acuity after femtosecond laser–enabled keratoplasty was significantly better than that after conventional penetrating keratoplasty (p = 0.00, standard mean difference: −0.23, 95% confidence interval: −0.37 to −0.10). Furthermore, endothelial cell density after femtosecond laser–enabled keratoplasty was preserved significantly better (p = 0.03, standard mean difference: 0.63, 95% confidence interval: 0.07–1.20). Moreover, spherical equivalent, graft rejection, graft failure, and complications represented no distinct differences between femtosecond laser–enabled keratoplasty and conventional penetrating keratoplasty (p > 0.05). Conclusion: Femtosecond laser–enabled keratoplasty may not be superior over conventional penetrating keratoplasty in decreasing postoperative topographic astigmatism, but might have advantages to achieve best-corrected visual acuity and endothelial cell density preservation. In addition, the two techniques seem to be comparable regarding spherical equivalent, graft rejection/failure, and complications.

The Effect of Pterygium Surgery on Corneal Topography

Objective To evaluate the effect of pterygium surgery on corneal topography by comparing wave front analysis before and one month after the surgical treatment. Methodology Fifty eyes of forty-one patients were included in this study. Twenty five male and sixteen female patients seeking pterygium surgery were recruited from the Ophthalmology Department Outpatient Clinic in Sohag Teaching Hospital during the period from July 2017 to May 2018. All eyes underwent pterygium excision with conjunctival autograft. Results In this study we found a highly statistically significant improvement in the mean uncorrected visual acuity from 0.44±0.21SD preoperatively to 0.62±0.18SD postoperatively (p &lt; 0.001) and a highly statistically significant difference in the mean logMAR visual acuity as it was decreased from 0.43±0.28 SD preoperatively to 0.34±0.23 SD postoperatively (p &lt; 0.001). Also, there was a highly statistically significant improvement in mean of manifest refractive astigmatism from -4.08±3.28 SD preoperatively to -1.46±1.40 SD postoperatively (p &lt; 0.001). We also found a highly statistically significant improvement in the mean cycloplegic astigmatism from -4.00±3.01 SD preoperatively to -1.39±1.33 SD postoperatively (p &lt; 0.001) and also there was a highly statistically significant improvement in the mean topographic astigmatism from -5.17±4.08 SD preoperatively to -2.20±2.31 SD postoperatively (p &lt; 0.001). We also found a highly statistically significant improvement in the mean of ISV (Index of Surface Variance) from 76.22±36.86 SD preoperatively to 33.56±15.02 SD post operatively (p &lt; 0.001) and also there was a highly statistically significant improvement in the mean IHD (Index of Height Decentration) from 0.042±0.027SD pre-operatively to 0.023±0.036 SD post operatively. Conclusion There was a highly statistically significant difference in the mean logMAR visual acuity and a highly statistically significant improvement in the mean uncorrected visual acuity. A highly statistically significant improvement in both refractive and topographic astigmatism after one month of the surgery was noted also. Here were also a highly statistically significant improvement in ISV and IHD that indicate improvement after pterygium removal. Recommendations Patient with pterygium that inducing astigmatism will benefit from surgical removal of the pterygium.

Treatment of the Pterygium: Autologous Conjunctival Implant Associated with Phototherapeutic Keratectomy (PTK), Second Experience

Aim: To evaluate for the second time the efficacy of new PTK formula for the treatment of the pterygium. Methods: The study was conducted on 10 eyes of 10 patients (5 eyes primary and 5 eyes with recurrent pterygium). It is a prospective non randomized study. We evaluated BCVA (Best Corrected Visual Acuity), mean refractive error (ME) and topographic astigmatism and recurrence of pterygium. Results: Mean post-operative BCVA increase significantly after the treatment. Recurrence of pterygium in the patients that underwent the surgery was 0%. Conclusion: This technique seems to be effective in the treatment of the pterygium. After the treatment, none of the patients presented a recurrence.

Vector Planning and Corneal Topographic Astigmatism

The concept of planning refractive laser treatments using parameters other than manifest or wavefront refraction was somewhat of a novelty until topography-guided treatments came to the forefront more recently. However, both forms of treatment still have their limitations: manifest and wavefront refraction-based treatments do not take into account the effects on corneal astigmatism, and topography-guided treatments do not take into account any astigmatism behind the cornea or any cortical processing involved in the patient’s subjective astigmatic perception. The answer to optimally correcting the astigmatism of the eye is to treat somewhere between the two extremes of refractive cylinder and corneal astigmatism. This can be done using the systematic approach of Vector Planning® (ASSORT Pty. Ltd., Cheltenham, Victoria, Australia). Vector Planning is a systematic approach designed to treat the maximum amount of astigmatism of the eye, while reducing the amount of corneal astigmatism remaining postoperatively compared to treatments based on refractive parameters alone.

Deep Anterior Lamellar Keratoplasty followed by Toric Lens Implantation for the Treatment of Concomitant Anterior Stromal Diseases and Cataract

Purpose To evaluate the outcomes of deep anterior lamellar keratoplasty (DALK) followed by phacoemulsification and toric intraocular lens (IOL) implantation for the treatment of concomitant stromal disease and cataract. Methods In this retrospective non-comparative interventional case series, ten eyes affected by stromal disease and cataract underwent DALK followed by phacoemulsification with toric IOL implantation after a minimum period of 5 months from complete suture removal. In each case, topographic astigmatism, refraction, visual acuity, and endothelial cell density were recorded before DALK and 1, 6, and 12 months after cataract surgery. In addition, IOL rotation was evaluated using anterior segment optical coherence tomography. Results Big-bubble DALK was performed in all eyes but one that received manual dissection. Topographic astigmatism averaged 5.6 ± 2.2 diopters (D) after suture removal; refractive astigmatism decreased to 0.55 ± 0.61 D as early as one month after cataract surgery and did not change substantially throughout the follow-up period. In all patients, one month after phacoemulsification uncorrected and best spectacle-corrected visual acuity were, respectively, ≥20/40 and ≥20/25 with a residual spherical equivalent of 0.00 ± 0.84 D. At the latest follow-up visit, in all cases the IOL rotation was ≤5 degrees from the intended position and the endothelial cell loss within 8.5%. No complications were recorded. Conclusions DALK followed by phacoemulsification with toric IOL implantation optimizes visual and refractive outcomes in patients with concomitant stromal disease and cataract. In comparison with a combined procedure, the sequential approach offers better predictability of the postoperative refraction in the absence of an increased risk of complications.

Accelerated Corneal Collagen Cross-Linking Using Topography-Guided UV-A Energy Emission: Preliminary Clinical and Morphological Outcomes

Purpose. To assess the clinical and morphological outcomes of topography-guided accelerated corneal cross-linking. Design. Retrospective case series. Methods. 21 eyes of 20 patients with progressive keratoconus were enrolled. All patients underwent accelerated cross-linking using an ultraviolet-A (UVA) exposure with an energy release varying from 7.2 J/cm2 up to 15 J/cm2, according to the topographic corneal curvature. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, topography, in vivo confocal microscopy (IVCM), and anterior segment optic coherence tomography (AS-OCT) were evaluated preoperatively and at the 1, 3, 6, and 12 months postoperatively. Results. 12 months after surgery UDVA and CDVA did not significantly vary from preoperative values. The average topographic astigmatism decreased from -4.61±0.74 diopters (D) to -3.20±0.81 D and coma aberration improved from 0.95 ± 0.03 μm to 0.88 ± 0.04 μm after surgery. AS-OCT and IVCM documented differential effects on the treated areas using different energies doses. The depths of demarcation line and keratocyte apoptosis were assessed. Conclusions. Preliminary results show correspondence between the energy dose applied and the microstructural stromal changes induced by the cross-linking at various depths in different areas of treated cornea. One year after surgery a significant reduction in the topographic astigmatism and comatic aberration was detected. None of the patients developed significant complications.