Omar, H. A., M. - S. H. El-Agha, M. A. Hassaballah, and N. M. Khalil, "Safety and Efficacy of Epithelial Island Crosslinking in Keratoconus with Thinnest Pachymetry less than 400µ.", Middle East African journal of ophthalmology, vol. 28, issue 1, pp. 11-17, 2021. Abstract

PURPOSE: To evaluate the efficacy and safety of epithelial-island crosslinking (EI-CXL) in keratoconus with corneas thinner than 400 µm.

METHODS: Twenty-six patients (30 eyes) underwent EI-CXL (preserving the epithelium over the thinnest area), using standard protocol (3 mW/cm for 30 min). Uncorrected and best spectacle-corrected distance visual acuity (UCDVA, BCDVA), manifest refractive spherical equivalent (SEQ), mean simulated keratometry (Kmean), maximum keratometry (Kmax), and thinnest corneal thickness (TCT) were determined preoperatively and at 1, 3, 6, and 12 months following CXL. Endothelial cell count (ECC) was determined preoperatively and at 6 months. Anterior segment optical coherence tomography (AS-OCT) was done at 1 month to determine the depth of the corneal stromal demarcation line (DL).

RESULTS: After 1 year, mean UCDVA improved from 1.29 preoperatively to 1.17 ( = 0.001) and BCDVA from 0.62 to 0.57 ( = 0.011). Mean manifest SEQ decreased from -7.63 to-7.32D ( = 0.001). Mean Kmean decreased from 54.92 to 54.81D ( = 0.045), and Kmax from 67.60 to 67.42D ( = 0.072), and mean TCT changed minimally from 377.17 to 375.30 µ ( = 0.11). The mean ECC decreased from 2329 to 2268 cells/mm (2.6% decrease, < 0.001). AS-OCT showed a DL in 29 out of 30 eyes at an average depth of 215.9 µ under the spared epithelium, and 299.9 µ in the de-epithelialized cornea.

CONCLUSION: EI-CXL halted keratoconus progression over a 1-year period. This was associated with statistically significant endothelial loss, but less than seen with conventional epi-off CXL in thinner corneas.

Tarek, N., N. M. Khalil, H. F. Elsheikh, and S. M. Shousha, "Evaluation of macular and peri-papillary blood vessel density following uncomplicated phacoemulsification in diabetics using optical coherence tomography angiography.", Indian journal of ophthalmology, vol. 69, issue 5, pp. 1173-1177, 2021. Abstract

Purpose: The aim of this study was to evaluate the macular and peri-papillary blood vessel density following uncomplicated phacoemulsification in diabetics using optical coherence tomography angiography (OCT-A).

Methods: An observational case-control study was conducted on 60 patients eligible for phacoemulsification, divided equally into diabetic and control groups. Both study groups were matching in sex, age, and axial length. We excluded diabetic patients of any form of macular edema or treatment history for macular edema. All study participants were subjected to preoperative OCT and OCT-A, which was repeated for all study population 1 month postoperatively.

Results: We had a mean age of 54.5 ± 6.34 years in the non-diabetic group and 57.2 ± 4.09 years in the diabetic group (P = 0.06). There was a significant increase in the mean value of the macular blood vessels density in the nasal area in both study groups (P = 0.047 in non-diabetic group, P = 0.002 in the diabetic group). The percentage of the radial peripapillary capillary plexus vessel density (RPCP VD) change was non-significant on comparing the results for the diabetic group (mean preoperative value = 52.8 ± 4.47, postoperative = 52.0 ± 4.59, P = 0.204, Δ is the preoperative-postoperative value = 0.8), and also was non-significant for the non-diabetic group (mean preoperative value = 50.9 ± 4.89, postoperative = 52.1 ± 4.89, P = 0. 0.090, Δ = -1.3). On comparing the results of the diabetic and nondiabetic groups, the RPCP VD Δ was significantly different (P = 0.034).

Conclusion: Uncomplicated phacoemulsification results in increase of the nasal macular blood vessel density in the normal population and in diabetic patients without retinopathy.

Hosny, M., R. M. Zaki, R. A. Ahmed, N. Khalil, and H. M. Mostafa, "Changes in retinal nerve fiber layer thickness following mechanical microkeratome-assisted versus femtosecond laser-assisted LASIK.", Clinical ophthalmology (Auckland, N.Z.), vol. 7, pp. 1919-22, 2013. Abstract

PURPOSE: To study the influence of the transient elevation of intraocular pressure during suction in laser-assisted in situ keratomileusis (LASIK) on the retinal nerve fiber layer (RNFL) thickness both in microkeratome assisted and femotsecond (FS) LASIK.

PATIENTS AND METHODS: An interventional case series that included 40 eyes suffering from myopia who were candidates for LASIK. All underwent Wave Front Guided LASIK by the same surgeon using the VisX CustomVue platform. A corneal flap was created in 20 eyes using a mechanical microkeratome Moria M2 (MMK), while the IFS IntraLase™ was used in the remaining 20 eyes. Mean suction time was recorded from "Suction ON" to "Suction OFF" time. Optic cube and RNFL thickness analysis using Spectral Domain Optical Coherence Tomography (SD-OCT) Cirrus-HD was completed before, and 1 month after LASIK.

RESULTS: The study included 40 eyes of 20 patients. All were females with mean age 33.5 ± 6.4 years. Mean preoperative spherical equivalent was -3.62 ± 2.31D. Average preoperative RNFL thickness was 94.6 ± 12.1μm in MMK group while the postoperative average thickness was 95.1 ± 11.9 um with no statistically significant difference (P-value: 0.37). Average preoperative RNFL thickness was 108.28 ± 8.4 μm in FS group compared to 108.38 ± 11.2 μm in the postoperative average with no statistically significant difference (P-value: 0.94). Mean "Suction ON" to "Suction OFF" time was 22 seconds in the MMK group compared to 41 seconds in the FS group.

CONCLUSION: The rise of intraocular pressure during application of suction ring in LASIK surgery does not affect the RNFL thickness as measured by SD-OCT, whether the flap is created by MMK or FS.

Allam, R. S. H. M., and N. M. M. M. Khalil, "Evaluation of sex differences in corneal hysteresis.", European journal of ophthalmology, vol. 25, issue 5, pp. 391-5, 2015 Sep-Oct. Abstract

PURPOSE: To study sex differences in corneal biomechanical parameters in Egypt as regards to corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc).

METHODS: This is a cross-sectional observational study that includes 350 eyes of 350 normal subjects (175 men and 175 women) who were evaluated using the Reichert ocular response analyzer (ORA) to measure CH, CRF, IOPg, and IOPcc.

RESULTS: The mean CH in men was 9.69 ± 2.05 mm Hg (range 5.7-14.6 mm Hg) and in women 10.41 ± 1.65 mm Hg (range 7-14.4 mm Hg) with a p value of 0.00038. The mean CRF in men was 9.54 ± 2.16 mm Hg (range 4.9-14.4 mm Hg) and in women was 10.37 ± 1.71 mm Hg (range 7.3-15.5 mm Hg) with a p value of 0.00008. The mean IOPg in men was 14.78 ± 4.15 mm Hg (range 7.2-26.5 mm Hg) and in women was 15.44 ± 3.3 mm Hg (range 8.6-23.7 mm Hg) with a p value of 0.09. The mean IOPcc in men was 16.2 ± 4.08 mm Hg (range 10.9-28.9 mm Hg) and in women was 15.86 ± 3.41 (range 9.7-24.2 mm Hg) with a p value of 0.4. There was a statistically significant difference between men and women in CH and CRF while IOPg and IOPcc showed no statistically significant difference (p>0.05).

CONCLUSIONS: There is a statistically significant difference between men and women in CH and CRF, where women show higher values, while no statistically significant difference exists between the groups in IOPg or IOPcc.

Eissa, I. M., N. M. Khalil, and H. A. El-Gendy, "A Controlled Study on the Correlation between Tear Film Volume and Tear Film Stability in Diabetic Patients.", Journal of ophthalmology, vol. 2016, pp. 5465272, 2016. Abstract

Purpose. To assess the tear film quantity and correlate it with the quality and stability of the tear film in diabetics and compare them to age matched controls. Introduction. Diabetes affects tear film parameters in multiple ways. Poor metabolic control and neuropathy are postulated factors. To further understand how diabetes affects tear film parameters this study was conducted. Subjects and Methods. Tear meniscus height was measured by anterior segment OCT, along with tear thinning time, a subtype of noninvasive tear break-up time, and blinking rate per minute which were all recorded for 22 diabetic patients. Correlations between these tear film parameters were studied and then compared to 16 age matched controls. Results. A statistically significant difference was found in blinking rate between the diabetic and the control group (P = 0.002), with higher blinking rate among diabetics. All tear film parameters were negatively correlated with duration of diabetes. A positive correlation was found between tear film volume and stability. Conclusion. Diabetes affects the tear film in various ways. Diabetics should be examined for dry eye signs even in absence of symptoms which may be masked by associated neuropathy. Duration of diabetes has an impact on tear film status.

Osman, M. H., N. M. Khalil, and M. - S. El-Agha, "Incidence of Posterior Vitreous Detachment After Femtosecond LASIK Compared With Microkeratome LASIK.", Cornea, vol. 36, issue 9, pp. 1036-1039, 2017 Sep. Abstract

PURPOSE: To compare the incidence of posterior vitreous detachment (PVD) after femtosecond and microkeratome laser in situ keratomileusis (LASIK).

SETTING: Rowad Correction Centre, Cairo, Egypt (a private center affiliated to Cairo University).

DESIGN: Prospective, nonrandomized comparative unmasked study.

METHODS: The study was conducted at a single laser center. Eligible patients chose between femtosecond and microkeratome LASIK after appropriate counseling. B-scan ultrasonography was performed before surgery by a single operator. Patients with preexisting PVD (partial or complete) were excluded. The axial length was also recorded. All surgery was performed by a single surgeon. During surgery, the suction time was measured. Ultrasonography was repeated 1 month after surgery by the same operator to detect PVD.

RESULTS: Ten patients (20 eyes, group M) underwent LASIK using the Moria M2 microkeratome, and 10 patients (20 eyes, group F) underwent femtosecond LASIK with the IntraLase FS-150. In groups M and F, respectively, the proportion of women was 80% and 70%, and the mean age was 24.7 ± 4 years and 25.7 ± 3.3 years, the mean axial length was 24.2 ± 1.2 and 23.8 ± 1.2 mm, and the mean suction time was 18 ± 2 seconds and 63 ± 4 seconds (P < 0.001). After surgery, PVD was detected in 4 eyes (20%) in group M and 17 eyes (85%) in group F (P = 0.000044).

CONCLUSIONS: The incidence of PVD 1 month after femtosecond LASIK was higher than after microkeratome LASIK. This may be due to longer suction time during femtosecond LASIK despite lower suction pressure.

Labib, T., H. F. E. Sheikh, N. A. Hassan, M. Gamal, and undefined, Surgical correction of pre-existing Astigmatism during phacoemulsification, , Cairo, Cairo University, 2009.
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