Correction of pre-existing astigmatism with phacoemulsification using toric intraocular lens versus spherical intraocular lens and wave front guided surface ablation.

BACKGROUND: This study aimed to evaluate toric intraocular lens to correct of pre-existing astigmatism at the time of phacoemulsification compared to using of spherical intraocular lens followed by wavefront guided surface ablation. RESULTS: The patients were classified into three groups: Group A with 20 eyes of 19 patients having phacoemulsification with spherical intraocular lens only as a control group, group B with 20 eyes of 14 patients had phacoemulsification with toric intraocular lens and group C with 20 eyes of 16 patients had phacoemulsification with spherical intraocular lens and wavefront guided PRK three months later. Comparison pre-operative data for all groups showed no statistically significant difference regarding UCVA, BCVA, MRSE, and refractive astigmatism (P>0.05). Post operatively, there was a statistically significant difference for UCVA, BCVA, MRSE, and refractive astigmatism for group A compared to group B (P<0.05) and group A compared to group C but there was no statistically significant difference for group B compared to C regarding all these parameters (P>0.05). CONCLUSION: In this study, we found similar effects for both techniques in astigmatism corrected groups while both differed from the control group that was not corrected. Correcting preexisting astigmatism during cataract surgery should be in mind in every case to improve visual outcomes. Longer period of follow up are required to evaluate stability of these techniques and possibility of regression.

Pediatric Keratoconus in A Tertiary Eye Center in Alexandria: A Cross-sectional Study.

PURPOSE: To describe the clinical presentation, risk factors, and treatment choices documented in a pediatric keratoconus population treated at a tertiary referral center in Alexandria, Egypt. METHODS: : A cross-sectional study of 80 patients with keratoconus aged 18 years or younger referred to the cornea clinic at the Alexandria University Main Hospital between July 2018 and October 2019 was included. Patients' history, initial presentation, best spectacle corrected visual acuity (BSCVA), clinical signs, topographic data, and treatment were recorded. RESULTS: Thirty patients were younger than 14 years and 50 were 14 years or older. Elements of the initial presentation included decreased vision in 26 patients, itching in 20 patients, both visual impairment and itching in 16 patients, accidental discovery during vision screening at school in 15 patients, and hydrops in three patients. All patients had bilateral keratoconus, except for four patients who had previously been treated by keratoplasty (n = 156 eyes). The mean logMAR BSCVA was 0.79 ± 0.63. The mean of the average keratometry (AveK), maximum keratometry (Kmax), central corneal thickness (CCT) and thinnest pachymetry reading were 51.16 ± 7.31 D, 59.18 ± 10.38 D, 458.44 ± 55.87 µ 440.08 ± 60.18 µ, respectively. 57 eyes (36%) had stage 1 disease, 43 eyes (28%) had stage 2 disease, 17 eyes (11%) had stage 3 disease and 39 eyes (25%) had stage 4 disease, respectively. No statistically significant differences in the LogMAR BSCVA, keratometry values, CCT, thinnest pachymetry reading, and the Amsler-Krumeich (AK) staging existed between the two age groups or between boys and girls. Crosslinking was indicated in 69 eyes (44%), while keratoplasty was the only viable solution for 39 eyes (25%), with three patients requiring keratoplasty in both eyes. CONCLUSION: Keratoconus in children can result in severe loss of vision. Keratoconus screening programs in elementary schools should be considered in populations with a high incidence of keratoconus for early detection and adequate intervention.

One-Year Outcomes of Intracorneal Ring-Segment Insertion Assisted by Femtosecond Laser Simultaneously Performed with Corneal Collagen Cross-Linking for Treatment of Keratoconus.

PURPOSE: To assess the results of simultaneously performed femtosecond laser-assisted Keraring intrastromal corneal ring-segment insertion and corneal collagen cross-linking for the treatment of keratoconus. PATIENTS AND METHODS: In this retrospective, noncomparative, interventional study, 30 eyes of 24 progressive-keratoconus patients of both sexes aged 18-36 years old with poor best-corrected visual acuity (BCVA) and intolerance to contact lenses were included. All patients had been subjected to complete preoperative and postoperative ophthalmological examinations - unaided VA, BCVA, refraction, Pentacam, and contrast sensitivity examinations at 3-month, 6-month, and 1-year follow-ups. RESULTS: Mean unaided VA had changed significantly from 0.649±0.239 logMAR preoperatively to 0.514±0.222 (P=0.014), 0.419±0.162 (P<0.001), and 0.379±0.142 (P<0.001) logMAR at the three follow-up visits, respectively. Mean BCVA had changed significantly from 0.326±0.144 logMAR preoperatively to 0.231±0.140 (P=0.006) at 1-year follow-up. Mean spherical equivalent refraction had decreased significantly at 6-month (P=0.0298) and 1-year follow-up (P=0.0081). Mean steep keratometry (K2) had also significantly reduced from 51.89±3.81 D to 49.87±4.57 D (P=0.034) at 6 months and 49.40±4.39 D (P=0.011) at 1 year. Mean refractive and keratometric astigmatism had significantly decreased at all follow-up visits. CONCLUSION: At 1-year follow-up, keraring intrastromal corneal ring-segment insertion assisted by femtosecond laser performed simultaneously with corneal collagen cross-linking resulted in an improvement in visual, refractive, and topographic outcomes, which may suggest it is an effective treatment of keratoconus.

Safety and Indicative Effectiveness of Porcine Corneal Lenticular Implants in Patients with Advanced Keratoconus and Post Lasik Ectasia: A Retrospective Clinical Study.

PURPOSE: This study aimed to evaluate the safety and feasibility of implanting decellularized porcine corneal lenticules in a femtosecond laser-assisted pocket for patients with advanced keratoconus and post-Lasik ectasia. METHODS: This is a retrospective clinical study of implanting a porcine corneal lenticular implant in seven eyes: six with advanced keratoconus and clear cornea and one with advanced post-Lasik ectasia with a follow-up for 12 months. The lenticules are extracted from porcine tissue, subjected to a decellularization process, intensely cross-linked, sterilized and packed. They are 7 mm in diameter with at 100-120-micron thickness. The femtosecond laser was used to create an intra-stromal pocket, and then the lenticules were implanted inside the pocket followed by corneal cross-linking 3 months later for six out of seven eyes. RESULTS: Five patients had keratoconus (6 eyes) and one patient (one eye) had post-Lasik ectasia. Visual acuity improved in all patients except for one case at 6 and 12 months and this was statistically significant (P=0.002 and 0.007). At one-year follow-up, the mean central corneal thickness increased from 389.43 ± 45.41 to 429.33± 63.20 µm, the maximum keratometry decreased from 64.8 ±5.11 to 62.82± 6.16 D, the mean corneal resistance factor (CRT) increased from 5.67 to 8.42, and the total higher-order aberrations decreased from 1.80 to 1.16. Both changes in the CCT and CRF were statistically significant. One eye had wrinkles and opacified graft, and it was exchanged 3 months postoperatively. CONCLUSION: Porcine corneal lenticules implantation is immunologically safe and well tolerated in patients with advanced keratoconus and post-Lasik ectasia and may be feasible as an alternative to keratoplasty.

Association Between Keratoconus and Thyroid Gland Dysfunction: A Cross-Sectional Case-Control Study.

PURPOSE: To examine the clinical association between thyroid gland dysfunction and keratoconus. METHODS: This was a cross-sectional case-control study conducted between May 2018 and July 2019. After performing Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) examination, flat, steep, and maximum simulated keratometric readings were recorded for each patient. Serum concentrations of free triiodothyronine, free thyroxine, and thyroid-stimulating hormone were measured. Further examinations by an endocrinologist were indicated for patients with positive laboratory results to confirm thyroid gland dysfunction. RESULTS: One hundred eighty-seven patients with bilateral keratoconus and 187 sex- and age-matched healthy controls without keratoconus were analyzed. Mean age was 26.4 ± 8.2 years for the patients with keratoconus and 27.1 ± 9.4 years for the control patients, with no significant difference. The results showed that thyroid gland dysfunction prevalence was 10 of 187 patients with keratoconus (5.3%) and 2 of 187 control patients (1.1%), and the difference was statistically significant (P = .036). For the patients with keratoconus and thyroid gland dysfunction, 8 were women and 2 were men. Additionally, 6 patients (2 men and 4 women) had hyperthyrosis and 4 women had hypothyrosis. For controls, the two patients had hypothyrosis. CONCLUSIONS: This study showed that there is a possible association between keratoconus and thyroid gland dysfunction, but more studies are needed to build upon these results. [J Refract Surg. 2020;36(4):253-257.].

Corneal biomechanics in different age groups.

PURPOSE: To report on the corneal biomechanical characteristics, namely the corneal hysteresis (CH), corneal resistance factor (CRF), as well as the intraocular pressure (IOP) goldman compensated (IOPg), and the cornea compensated (IOPcc), using the ocular response analyzer (ORA) in different age groups in a cohort of normal individuals from the second decade to the seventh decade and beyond. PATIENTS AND METHODS: The study was a cross-sectional survey conducted on 997 eyes of 508 normal individuals presenting for a routine ophthalmic examination at Alexandria Main University Hospital in Alexandria University, Alexandria, Egypt. The study subjects were age stratified into decades (10-20, 21-30, 31-40, 41-50, > 50) and the ORA parameters (CH, CRF, IOPg, IOPcc) reported and stratified. Correlations were sought between the ORA parameters and the age, gender, and laterality. RESULTS: The study was conducted on 997 (502 right) eyes of 508 (234 males) normal individuals. The mean ± SD ages of the study groups were 14.7 ± 3.2, 25.9 ± 3.0, 35.3 ± 2.8, 44.6 ± 2.9, and 61.1 ± 7.7 years. The mean ± SD of the CH in the study groups were 10.9 ± 2.4, 9.8 ± 1.5, 9.8 ± 1.4, 9.7 ± 1.7, and 9.5 ± 1.6 mmHg and of the CRF were 10.9 ± 2.4, 9.5 ± 1.7, 9.4 ± 1.8, 9.6 ± 1.9, and 9.6 ± 1.8 mmHg. A statistically significant negative correlation was found between age and each of CH and CRF. IOPcc demonstrated a fairly constant trend in the different age groups whereas IOPg demonstrated an initial decline followed by a gradual rise over time. CONCLUSION: The corneal biomechanical properties CH and CRF decrease with age. IOPg and IOPcc change minimally with age.

Bilateral, Asymmetric Keratoconus Induced by Thyrotoxicosis With Long-term Stability After Corneal Cross-linking.

PURPOSE: To present a case of bilateral, asymmetric keratoconus presenting unilaterally after partial thyroidectomy with delayed presentation in the second eye after thyrotoxicosis, with disease stabilization following corneal cross-linking (CXL). METHODS: Case report and literature review. RESULTS: A 17-year-old girl with a history of Graves' disease underwent partial thyroidectomy without thyroid hormone replacement therapy with normal baseline ophthalmic examination of corrected distance visual acuity (CDVA) of 20/20 and no manifest astigmatism in either eye. At age 29 years, keratoconus manifested in the right eye and standard protocol CXL was performed. At age 40 years, the right eye remained stable after CXL, but keratoconus manifested in the left eye and epithelium-off accelerated CXL was performed with subsequent disease stabilization. CONCLUSIONS: This case demonstrates the association between thyrotoxicosis and keratoconus and the bilateral nature of keratoconus, and highlights the potentially asymmetric presentation of thyroid-induced keratoconus. CXL had a long-term stabilizing effect over 10 years despite the ongoing effects of thyroid gland dysfunction. [J Refract Surg. 2018;34(5):354-356.].

Evaluation of the effect of corneal collagen cross-linking for keratoconus on the ocular higher-order aberrations.

BACKGROUND: Corneal collagen cross-linking (CXL) is the only treatment currently available to arrest the progression of keratoconus. The procedure consists of photopolymerization of stromal collagen fibers induced by combined action of a photosensitizing substance (riboflavin or vitamin B2) and ultraviolet-A light. PURPOSE: To determine changes in the ocular higher-order aberrations (HOAs) after CXL and its correlation with changes in visual acuity. DESIGN: Prospective interventional study. SUBJECTS AND METHODS: This study was conducted on 30 eyes of 16 patients with progressive keratoconus documented between 2012 and 2014. Patients were treated with epithelium-off CXL and followed for a minimum of 6 months. The following ocular HOAs were measured and analyzed using I-Tracey Aberrometer: coma, trefoil, spherical aberration, astigmatism, and total HOAs. RESULTS: There was statistically significant improvement in uncorrected visual acuity and best-corrected visual acuity between the preoperative and 6-month evaluations (P<0.001). Total HOAs and total coma were statistically significantly reduced at 6 months by 25% and 18%, respectively. Significant improvement was seen in spherical aberration by 8.71% (P<0.001), while no significant change was observed in trefoil and high order astigmatism (P=0.405 and 0.329, respectively). There was a statistically significant change in the average (K) value at the apex between the preoperative values and the 6-month values (P<0.05). CONCLUSION: Total HOAs, total coma, and spherical aberrations decreased after CXL. Coma has a direct relationship with the improvement of visual function.

Contralateral Eye Comparison Between Femtosecond Small Incision Intrastromal Lenticule Extraction at Depths of 100 and 160 µm.

PURPOSE: To compare the visual results, higher-order aberrations, and corneal biomechanical properties of femtosecond small incision lenticule extraction (SMILE) at depths of 100 and 160 µm. METHODS: A prospective comparative interventional clinical trial of a series of patients who underwent SMILE. In the right eye, a refractive lenticule was created at a depth of 100 µm, and in the left eye, a depth of 160 µm was used. Manifest refraction, uncorrected visual acuity, total high-order aberrations (THOA), and corneal biomechanical properties of both eyes were evaluated 1 month postoperatively. RESULTS: Thirty patients with bilaterally stable refractive errors were included in this study. One month postoperatively, mean corneal hysteresis was 9.71 ± 0.68 in the right eyes and 9.97 ± 0.77 in the left eyes, whereas the mean corneal resistant factor was 9.13 ± 1.04 and 9.31 ± 0.92 in the right and left eyes, respectively. Both corneal hysteresis and corneal resistant factor showed statistically significantly higher values in the left eyes (lenticule at a depth of 160 µm). No statistically significant differences were found between the right and the left eyes regarding manifest refraction, uncorrected visual acuity, and THOA. CONCLUSIONS: Creating the refractive lenticule at a depth of 160 µm in SMILE had less effect on the corneal biomechanics than did creating a lenticule at a depth of 100 µm with no statistically significant differences in the refractive outcome and THOA between both groups.

Ocular response analyzer and goldmann applanation tonometry: a comparative study of findings.

PURPOSE: Correlation of findings of the Reichert Ocular Response Analyzer (ORA) with Goldmann applanation tonometry (GAT). DESIGN: Observational, cross-sectional study. METHODS: The study was conducted on 103 eyes of 56 patients, aged 41 to 78 years; average (±SD) 58.9 (±9.8) years attending the outpatient clinic of the Department of Ophthalmology, Alexandria University, for a routine refraction. Full ophthalmic examination including slit lamp biomicroscopy and GAT, then Reichert ORA utilization to obtain the intraocular pressure cornea corrected (IOPcc), the IOP Goldmann (IOPg), the corneal resistance factor (CRF), the corneal hysteresis (CH), and the central corneal thickness (CCT). Exclusion criteria included previous ophthalmic surgery and any corneal pathology. RESULTS: The mean (±SD) IOP GAT was 14.1 mm Hg (±3.0) (range: 8 to 22 mm Hg). The mean (±SD) IOPg, IOPcc, CRF, CH, and CCT was 15.5 (±4.0), 16.9 (±3.7), 9.6 (±2.0), 9.4 mm Hg (±1.7) and 540.8 (±32.6) µm, respectively. There was a significant correlation (P<0.0001) between IOP GAT and each of IOPg, IOPcc, and CRF; between IOPg and each of IOPcc, CRF, and CCT; between IOPcc and each of CRF and CH; and between CCT and each of CRF and CH at 0.01 level. The average (±SD) difference between IOP GAT and IOPg and IOPcc was -1.33 (±2.38) mm Hg and -2.81 (±2.66) mm Hg, respectively, and was statistically significant (paired t test in a 95% confidence interval). CONCLUSIONS: The ORA is valuable for the evaluation of IOP and corneal biomechanics. However its results are not to be used interchangeably with the GAT findings.