Studying the contribution of posterior corneal astigmatism to total corneal astigmatism

Settings The Faculty of Medicine, Alexandria University, Egypt. Purpose The aim of this work was to study the contribution of posterior corneal astigmatism to total corneal astigmatism. Patients and methods A descriptive prospective observational study that included 100 eyes of 100 patients aged 18 years and above. Scheimpflug camera imaging was performed using a Pentacam. The following data were recorded: anterior corneal radii of curvature, posterior corneal radii of curvature and astigmatism, simulated keratometry (sim K) and astigmatism, the true net power and astigmatism, and central corneal pachymetry. All included participants signed a written informed consent. Results The mean age was 38.11 ± 12.69 years. The orientation of the steep axis of the anterior corneal surface was vertical in 70% of the cases, resulting in with-the-rule astigmatism. For the posterior corneal surface, the steep axis orientation was vertical in 94% of the cases, resulting in against-the-rule (ATR) astigmatism. The mean sim K astigmatism was higher than that of the true net K astigmatism by 0.12 ± 0.18 D (range -0.3-0.4 D) at 4 ± 5° (range 0-21°). Conclusion Anterior corneal with-the-rule astigmatism tends to change to ATR astigmatism with age. The posterior corneal surface showed ATR astigmatism regardless of the age. Using data from the anterior corneal surface only resulted in a higher astigmatism of 0.12 D compared with using data from both the anterior and the posterior surfaces. Also, data from the anterior corneal surface alone resulted in a difference in the axis of more than 10° in 11% of the cases

Graft Survival after Penetrating Keratoplasty in Cases of Trabeculectomy versus Ahmed Valve Implant

Purpose. To compare the corneal graft survival rates after penetrating keratoplasty (PKP) in cases of post-PKP glaucoma managed by either trabeculectomy with mitomycin C or Ahmed glaucoma valve (AGV). Methods. This study was a retrospective interventional comparative study that included 40 eyes of 40 patients. The included patients had undergone previous PKP for anterior segment reconstruction after microbial or fungal keratitis, chemical burns, trauma, or perforated corneal ulcer. Post-PKP glaucoma was managed surgically by either trabeculectomy with mitomycin C (group 1) or Ahmed glaucoma valve (group 2). Results. The first group n=20 had undergone trabeculectomy with MMC, and the second group n=20 had undergone AGV implantation. Regarding BCVA, there was no statistically significant difference between the 2 groups. Mean IOP was significantly lower in the AGV group at 6 months, 12 months, and 24 months p=0.001. Mean IOP at 24 months dropped significantly from preglaucoma surgery levels in both groups p=0.001. Rejection episodes occurred in 2 eyes (10%) of the trabeculectomy group versus 8 eyes (40%) in the AGV group p=0.028. In the trabeculectomy group, corneal graft failure occurred in 1 (5%), 3 (15%), and 6 (30%) eyes at 6 months, 12 months, and 24 months, respectively. In the AGV group, corneal graft failure occurred in 2 (10%), 5 (25%), and 10 (50%) eyes at 6 months, 12 months, and 24 months, respectively. The mean time to failure in the trabeculectomy group was 12.33 ± 5.60 months versus 11.90 ± 5.70 months in the AGV group p=0.027. Conclusion. Managing postpenetrating keratoplasty glaucoma could be bothersome especially in complex cases. Ahmed glaucoma valve implant controls the intraocular pressure more effectively than trabeculectomy with mitomycin C. However, Ahmed glaucoma valve can result in higher rates of corneal graft failure in a shorter duration of time. This trial is registered with PACTR201712002861391 on 21 Dec 2017

Outcome of Primary Nonpenetrating Deep Sclerectomy in Patients with Steroid-Induced Glaucoma

Purpose. To evaluate the outcome of primary nonpenetrating deep sclerectomy (NPDS) in patients with steroid-induced glaucoma. Methods. This was a retrospective interventional clinical study that included 60 eyes of 60 steroid-induced glaucoma patients that had undergone NPDS. Patients were followed up for 4 years. Data from the records was retrieved as regards corrected distance visual acuity (CDVA), intraocular pressure (IOP), visual field mean defect (dB), and number of antiglaucoma medications needed if any. Complete success of the surgical outcome was considered an IOP ≤ 21 mmHg with no antiglaucoma medications. Qualified success was considered an IOP ≤ 21 mmHg using antiglaucoma medications. Results. The mean age was 21.2 ± 8.5 years (ranged from 12 to 35 years). At 48 months, mean IOP was 13.6 ± 2.8 mmHg (range 11–23 mmHg). This represented 60% reduction of mean IOP from preoperative levels. One case had YAG laser goniopuncture. Three cases required needling followed by ab interno revision. Using ANOVA test, there was a statistically significant difference between preoperative and postoperative mean IOP values (P=0.032). Twelve, 16, and 20 patients required topical antiglaucoma medications at 24, 26, and 48 months postoperative, respectively. Conclusion. Primary nonpenetrating deep sclerectomy is a safe and an effective method of treating eyes with steroid-induced glaucoma. No major complications were encountered. After 4 years of follow-up, complete success rate was 56.7% and qualified success rate was 70%

Comparison between Refractive Outcome of Primary Piggyback Intraocular Lens versus Secondary Lens Iris Claw Lens in Posterior Microphthalmos

Purpose. To compare the refractive outcome of 2 different methods of intraocular lens implantation in cases of posterior microphthalmos, primary piggyback IOLs versus secondary iris claw lenses. Methods. This study was a retrospective interventional comparative study that included 60 eyes of 30 patients. The included patients had bilateral microphthalmos with high axial hyperopia and had undergone a lens-based surgical procedure for hyperopia correction. The included patients were equally divided into two groups. The first group had undergone refractive lens exchange (RLE) with primary piggyback IOL implantation. The second group undergone RLE with maximum available IOL power implanted followed by a secondary implantation of Artisan iris-fixated IOL (Ophtec B.V., Groningen, the Netherlands). Results. The 2 groups were highly comparable to each other regarding the mean age, axial length (AL), manifest refraction (MR), and K readings. Postoperatively, there was a statistically significant difference between the 2 groups regarding the manifest refraction spherical equivalent (MRSE), mean absolute error (MAE), and uncorrected distance visual acuity (UDVA). There was no significant difference between the 2 groups regarding the CDVA. At 36 months, 20% and 73% of the eyes were within ±0.5 D of intended refraction at 36 months in 1ry piggyback and 2ry Artisan groups, respectively. Fifty-three percent and 93% of the eyes were within ±1.0 D of intended refraction at 36 months in 1ry piggyback and 2ry Artisan groups, respectively (p=0.001). Conclusion. Secondary procedure with implantation of iris-fixated intraocular lens yielded very good results for treatment of axial hyperopia in cases of posterior microphthalmos. The primary piggyback IOL showed less satisfactory results with cases of under correction and the possible complication of interlenticular opacification. Both groups showed good safety parameters

Traumatic Wound Dehiscence after Keratoplasty: Characteristics, Risk Factors, and Visual Outcome

Purpose. The study aimed at evaluating the patients’ characteristics, risk factors, complications, and visual outcome of traumatic wound dehiscence after keratoplasty. Patients and Methods. A retrospective case series that included 20 eyes of 20 patients who had undergone a previous keratoplasty procedure followed by traumatic wound dehiscence. Records of the selected patients were reviewed. The mean duration of follow-up after repair was 21 months. Included patients were recalled for the final follow-up visit. Results. The procedure of corneal transplantation was penetrating (PKP) in 16 eyes and deep anterior lamellar keratoplasty (DALK) in 4 eyes. The associated anterior segment injuries included iris prolapse in 17 eyes and lens extrusion in 12 eyes. The associated posterior segment injuries included vitreous hemorrhage in 11 eyes and retinal detachment in 4 eyes. The final BSCVA was 0.1 or better in 5 cases (25 %) and was better than hand motions (HM) to less than 0.1 in 7 cases (35 %). Conclusion. Traumatic wound dehiscence following keratoplasty results in poor visual outcome. Cases following DALK may have less wound extent and better final visual outcome. The dehiscence seems most likely to occur during the first year

Comparison of Endothelial Cell Loss following the Big Bubble versus the Microbubble Incision Technique during Deep Anterior Lamellar Keratoplasty in Eyes with Keratoconus

Introduction. Deep anterior lamellar keratoplasty (DALK) is now becoming an increasingly popular surgical technique in treating corneal stromal pathologies with healthy endothelium. Several advantages of DALK over penetrating keratoplasty (PKP) have been described such as maintenance of globe integrity, absence of endothelial rejection, and a low rate of chronic endothelial cell loss (ECL). ECL following PKP results in 50% cell loss after 2 years from the estimated graft endothelial cell density (ECD). Although there are several reports confirming that ECL following DALK is similar to the physiologic cell loss 2 years after surgery, few reports discussed the surgically induced ECL due to difficulty in preoperative imaging of ECD. Materials and Methods. This prospective, interventional study included 20 eyes of 20 patients, who underwent DALK surgery. 11 eyes underwent DALK using the big bubble technique, while 9 eyes underwent the microbubble technique. Postoperative evaluation was done 3 months after surgery and included best spectacle corrected visual acuity (BSCVA), keratometric readings, and refraction measured using an autokeratorefractometer (Topcon KR800, Japan) and endothelial cell density (ECD) using noncontact specular microscopy (Nidek CEM-530, Japan). Results. Regarding postoperative parameters such as postoperative logMAR visual acuity, postoperative mean K, and postoperative K max, there was no statistical difference found between both groups (P=0.754, P=0.119, and P=0.970, respectively). Regarding change in specular endothelial cell density and percent change in the specular endothelial cell density, again there was no statistical difference between both groups with P=0.057 and P=0.126, respectively (significance defined as P<0.05). Conclusion. ECD is not affected by failure of the big bubble to form and continuing DALK via the microbubble technique

Corneal Safety and Stability in Cases of Small Incision Lenticule Extraction with Collagen Cross-Linking (SMILE Xtra)

Purpose. To assess the safety and stability in cases of small incision lenticule extraction with collagen cross-linking (SMILE Xtra). Methods. This study was a retrospective interventional comparative study that included 60 eyes of 30 patients divided equally into two groups: SMILE Xtra and SMILE alone. The inclusion criteria were patients >18 years of age, myopic error >6 D, thinner cornea <520 microns, and abnormal corneal topography. Outcome data were recorded including uncorrected distance visual acuity and corrected distance visual acuity (UDVA and CDVA), manifest refraction spherical equivalent (MRSE), central corneal thickness, average keratometry, endothelial cell density, corneal resistance factor (CRF), and corneal densitometry. The follow-up period was 24 months. Results. There was a significant difference between the 2 groups regarding UDVA, CDVA, and MRSE at 1 month. In the SMILE Xtra group, 90% of eyes had postoperative UDVA of 20/20 and 97% had UDVA of 20/30 at 24 months. At 24 months, 26 eyes (87%) vs. 25 eyes (84%) were within ±0.50 D of attempted correction in SMILE Xtra and SMILE groups, respectively. Regarding stability, both groups showed improvement of MRSE at 1st month postoperatively and remained stable along the 24 months of follow-up. CRF and corneal densitometry were higher in the SMILE Xtra group along the whole follow-up period (p=0.001). Conclusion. Combining corneal cross-linking with SMILE procedure (SMILE Xtra) is a promising tool to prevent ectasia in high-risk patients. It is a safe and simple procedure that can be offered to patients undergoing SMILE with risk for ectasia. Trial registration no: PACTR201810577524718

Corneal biomechanical changes in eyes with small incision lenticule extraction and laser assisted in situ keratomileusis

BACKGROUND: Evaluating the corneal biomechanical changes using the Ocular Response Analyzer and the Corvis ST in eyes with incision lenticule extraction (SMILE) and laser assisted in situ keratomileusis (LASIK). METHODS: This is a retrospective study that included 50 eyes equally divided into two groups. The first group included eyes that underwent SMILE procedure using VisuMax® 500 kHz laser system (Carl Zeiss Meditec, Jena, Germany) and the second group included eyes that underwent LASIK procedure using the EX500 Allegretto excimer laser platform (Wavelight GmbH, Erlangen, Germany). The Ocular Response Analyzer (ORA) and the Corvis ST (CST) measured the corneal biomechanical changes before and after the procedures. RESULTS: The ORA showed significant decrease of corneal hysteresis (CH) and corneal resistance factor (CRF) in both groups postoperatively. The percentage of change of CH and CRF were found to be significantly higher in group II. There was no significant difference in the IOP with the ORA and the CST pre and postoperatively in either group. Using CST, the deformation amplitude and HC peak distances increased significantly in both groups. It was also noted that the mean percentage of change of the deformation amplitude was nearly five times higher in group II than group I. CONCLUSION: Both LASIK and SMILE substantially decreased the corneal biomechanical properties with greater reduction in the LASIK group