Comparing Pentacam HR Screening Indices in Different Normal Corneal Thicknesses among Refractive Surgery Candidates.

Purpose: To compare Pentacam indices in normal eyes with different corneal thicknesses. Methods: It is a retrospective observational study. Ninety-six normal eyes of 96 patients who were referred for refractive surgery in a tertiary university-based hospital from October 2015 to April 2019 were recruited consecutively. Corneal keratometry as well as Pentacam's software Belin-Ambrósio Enhanced Ectasia Display (BAD) parameters including pachymetry progression indices (PPIs), maximum Ambrosio's relational thickness (ART-max), corneal elevations, normalized deviations, BAD total deviation value (BAD-D), and anterior surface indices were measured by Pentacam HR (Type 70900). The included were classified as thin (26 eyes), average (45 eyes), and thick (25 eyes) corneas with the thinnest point thickness of ≤496 µm, 497-595 µm, and ≥596 µm, respectively. The specificities of all parameters were calculated based on routine cut-off values. Results: The refraction, keratometry, and elevations were not different (P > 0.05). All PPIs (minimum, average, and maximum) of thick corneas were significantly lower than average and thin corneas (P < 0.001). ART-max increased by thickening of the cornea (P < 0.001). BAD-D score and normalized indices of pachymetric parameters decreased with the increase of thickness (P < 0.001), while specificities of all indices increased with corneal thickening. More than 96% of thick corneas were classified as normal PPI-max (24/25), ART-max (25/25), and BAD-D (25/25), while nearly <54% of thin corneas (14/26 for PPI-max, 9/26 for ART-max, and 12/26 for BAD-D) were normal. Conclusions: The pachymetry-related indices and BAD-D were different among normal corneas with various thicknesses. The specificities of PPIs, ART-max, and BAD-D of thin corneas were lower than in thick corneas.

Ocular Biometric Values and Prevalence of Corneal Astigmatism in Patients Candidate for Cataract Surgery.

Purpose: To analyze the biometric values and the prevalence of corneal astigmatism in cataract surgery candidates. Methods: This is a prospective study. Ocular biometric values and corneal keratometric astigmatism were measured by optical low-coherence reflectometry (Lenstar LS 900) before surgery in patients who were candidates for cataract extraction surgery. Descriptive measurements of biometric dimensions and keratometric cylinder data and their correlations with sex and age were evaluated. Results: Ocular biometric and keratometric values from 2084 eyes of 2084 patients (mean age 66.43, range 19-95 years) were analyzed. The mean values were as follows: corneal astigmatism 0.89 diopter (D), mean corneal keratometry 44.29 D, central corneal thickness 534 µ, internal anterior chamber depth (ACD) 3.11 mm, lens thickness 4.50 mm, and axial length 23.35 mm. Corneal astigmatism was <1.25 D in 1660 (79.5%) of eyes. Astigmatism was with-the-rule in 976 (46.8%) of eyes, against-the-rule (ATR) in 702 (33.7%), and oblique in 406 (19.5%). Analysis of corneal astigmatism revealed a change toward "ATR" with age which was not statistically significant. The ACD was correlated with age. The amount of corneal astigmatism had no correlation with age and sex. Conclusion: Corneal astigmatism was higher than 1.25 D in about 21% of cataract surgery candidates with slight differences between the various age ranges and had no correlation with age and sex.

Outcomes of a Single-Segment Intrastromal Corneal Ring in Early Keratoconus and Early Pellucid Marginal Degeneration.

PURPOSE: To determine the effect of a single-segment intrastromal corneal ring segment (ICRS; Intacs SK) on early keratoconus (KCN) and pellucid marginal degeneration (PMD). METHODS: It is a prospective interventional study. One hundred twenty-four eyes (99 patients) with KCN and 36 eyes (26 patients) with PMD at early stage (the maximum keratometric reading less than 55 diopters) were included to ICRS implantation using femtosecond laser at a tertiary university-based hospital and a private outpatient center. The uncorrected distance and spectacle-corrected visual acuity (UDVA and SCDVA), manifest spherical and cylindrical refractions, and keratometry indices were measured preoperatively and postoperatively, 1 week, 2 and 6 months. RESULTS: One week after surgery, significant improvements were observed in UDVA, SCDVA, cylinder and keratometry readings of both KCN and PMD groups (all P < 0.05) with no significant changes afterward. No significant change occurred in the sphere refraction of PMD group (P = 0.10) in contrast to KCN group (P < 0.001). Corneal irregularity of KCN group in central 3 and 5 mm zones increased at 1 week (both P < 0.001) and then started to decrease up to 6 months. However, the corneal irregularity of PMD group had significant reduction only at 1 week in 5-mm zone (P = 0.02) and 2 months in 3-mm zone (P = 0.01) postoperatively. The final efficacy indexes were 1.44 ± 0.71 and 0.87 ± 0.40 in KCN and PMD groups, respectively. CONCLUSION: Visual acuity, refractive errors and keratometry values have been improved after one-segment Intacs SK implantation in early KCN and PMD patients.

Comparison of video-based observation and direct observation for assessing the operative performance of residents undergoing phacoemulsification training.

Purpose: To compare the video observation of procedural skills (VOPS) method with the direct observation of procedural skills (DOPS) method in the assessment of senior residents' performance utilizing the International Council of Ophthalmology's Ophthalmology Surgical Competency Assessment Rubric for phacoemulsification (ICO-OSCAR; phaco). Methods: This is a prospective comparative study conducted at a university-affiliated hospital. Six ophthalmology residents of postgraduate year 4 participated. Their performance in phacoemulsification was rated via DOPS and later in a masked manner through VOPS by a single faculty assessor. Results: Seventy-one surgeries were evaluated. There were no statistically significant differences between the scores of VOPS and DOPS regarding all ICO-OSCAR indices except "instrument insertion into the eye" in which DOPS had higher scores (P = 0.035). A significant correlation was observed in total scores of "task-specific" (r = 0.64, P < 0.001) and "global" (r = 0.38, P = 0.003) indices between VOPS and DOPS while some subscales did not show a correlation between the two methods of assessment. The Bland-Altman analysis demonstrated that nearly all data points of total "task-specific" and "global" scores fell within the 95% limits of agreement ([-5.84, 6.87] and [-4.78, 4.86], respectively). Conclusion: This study demonstrated that VOPS holds promise for a general rating of residents' performance.

Intra-silicone Oil Injection of Methotrexate in Retinal Reattachment Surgery for Proliferative Vitreoretinopathy.

Purpose: To evaluate the role of intrasilicone oil injection of methotrexate (MTX) at the end of vitrectomy surgery for rhegmatogenous retinal detachment (RRD) associated with proliferative vitreoretinopathy (PVR).Methods: In this prospective comparative study, pars plana vitrectomy and retinal reattachment were performed for eyes with RRD with grade C PVR. In the MTX group, 250 µg MTX was injected into the silicone oil at the end of surgery. The rate of retinal redetachment associated with PVR was assessed.Results: In total, 44 eyes of 44 patients (22 in the MTX group and 22 controls) were included. Baseline characteristics were similar between the two groups. Retinal redetachment occurred in one eye (4.5%) in the MTX group and five eyes (22.7%) in the control group (p = 0.18). The change in visual acuity was similar between the two groups at final visit (p = 0.15).Conclusion: The rate of redetachment associated with PVR was lower after intrasilicone injection of MTX at the end of vitrectomy for RRD with severe PVR compared to control group; however, the difference was not statistically significant.

Intraocular lens power calculation in keratoconus; A review of literature.

PURPOSE: To review the published literature regarding cataract surgery in keratoconus (KCN) patients with emphasis on challenges encountered during intraocular lens (IOL) power calculation and their solutions. METHODS: A literature review was performed to investigate all the relevant articles on the advancements of IOL calculations in KCN patients. RESULTS: Cataract surgery in keratoconic eyes can improve patients' refraction, and proper patient selection and IOL calculation methods are necessary to get the best results. The main problem in KCN patients is unreliable biometric measurements. It is more difficult to make conclusions in more advanced keratoconic corneas, as the steep keratometric values in these eyes will result in the selection of a low-power IOL. Presence of a low-power IOL will yield in extreme postoperative hyperopia, and IOL exchange might be mandatory. In cases in which keratoplasty may be needed in the future, contact lens fitting can help surgeons make a better decision preoperatively. Axial length (AL) measurements may have better repeatability and reproducibility than keratometry (K) readings in keratoconic eyes. SRK II formula may provide the most accurate IOL power in mild KCN. There is still not a comprehensive consensus of which formula is the best one in moderate and severe KCN, as the literature is limited in this subject. CONCLUSIONS: Various methods of IOL power calculation optimization and recommendations may hold the key to improve surgical outcomes in keratoconic eyes. There are multiple sources of biometric error in KCN patients, hence IOL calculation methods may not be as efficient as expected in these eyes.

Safety of the subconjunctival injection of doxycycline in rabbits.

Purpose: To evaluate the safety of subconjunctival injection of doxycycline in rabbit eyes. Methods: Eight white New Zealand rabbits were selected. Different concentrations of 250 micrograms (µg), 500 µg, 1000 µg, and 2000 µg in 0.1 ml were prepared for subconjunctival injection. Each concentration was injected into the two eyes of each rabbit. For each dose, dextrose was injected in one contralateral eye and the other fellow eye remained non-injected. All rabbits underwent ocular examination in the 1st, 3rd, and 30th day after injection. The rabbits were sacrificed 30 days after injections and the histopathological examination was performed. Results: No obvious change was detected in all four groups from the 1st day to the 3rd day after injection in terms of tearing, hyperaemia, and chemosis. There was no visible sign of inflammation or necrosis, and also no histological change in both clinical and histopathological examinations. Conclusion: Subconjunctival injection of doxycycline with different dosages of 250 to 2000 ug in 0.1cc in rabbit eyes was safe and no clinical or histological changes were observed after one month.

Pseudomonas aeruginosa Endophthalmitis: Clinical Outcomes and Antibiotic Susceptibilities.

PURPOSE: To report the clinical characteristics, antibiotic susceptibilities, and visual outcomes for eyes with endophthalmitis caused by Pseudomonas aeruginosa. METHODS: In this retrospective, non-comparative case series, medical records of eyes with culture-proven Pseudomonas aeruginosa endophthalmitis, who were treated from April 2005 to April 2015 at a referral center in Tehran were reviewed. Clinical features, antibiotic susceptibilities, and visual outcomes were assessed. RESULTS: In total, 20 eyes of 19 patients were identified. The clinical settings included cataract surgery (85%), pars plana vitrectomy (5%), endogenous source (5%), and intravitreal bevacizumab injection (5%). Presenting visual acuity ranged from 20/120 to no light perception. Pars plana vitrectomy with intravitreal antibiotic injection was performed as the initial treatment in 16 eyes (80%). The organisms were sensitive to ciprofloxacin and imipenem in 100%; amikacin in 88.3%; ceftazidime in 83.4%; and tobramycin in 83.4% of isolates tested. Final visual acuity was hand motions or worse in 18 eyes (90%). Evisceration was performed in five eyes (20%). CONCLUSIONS: Susceptibility to ciprofloxacin and imipenem was found in all isolates tested. Despite appropriate treatment, visual and anatomic outcomes were generally poor.

Effect of Intravitreal Injection of Methotrexate on Human Corneal Endothelial Cells.

PURPOSE: To evaluate the toxic effect of intravitreal methotrexate on human corneal endothelium. METHODS: In this prospective noncomparative interventional case series, intravitreal injection of 400 µg methotrexate was performed in eyes with persistent diabetic macular edema. Corneal endothelial cell analyses and central corneal thickness measurements were performed before and 1, 3, and 6 months after injections, using noncontact specular microscopy. RESULTS: Twenty one eyes of 18 patients with a mean age of 60.5 ± 6.8 years were evaluated. No statistically significant difference was found in endothelial cell density, coefficient of variation, average cell area, hexagonality, and central corneal thickness measurements before and after injections (P = 0.70, 0.39, 0.43, 0.64, and 0.67, respectively). CONCLUSIONS: In this 6-month follow-up study, intravitreal injection of 400 µg methotrexate had no significant effect on corneal endothelial cell measurements performed by specular microscopy.

Endophthalmitis after resident-performed intravitreal bevacizumab injection.

OBJECTIVE: To evaluate the rate of acute endophthalmitis after resident-performed intravitreal bevacizumab (IVB) injections and to compare the results with those performed by attending retina surgeons. DESIGN: Retrospective comparative case series. PARTICIPANTS: Eight thousand thirty-seven patients treated with intravitreal injection of bevacizumab. METHODS: A retrospective chart review of the resident-performed IVB injections at Rassoul Akram Hospital and attending-performed IVB injections at a private eye clinic between 2011 and 2014 was undertaken. Cases of clinical endophthalmitis were identified. RESULTS: During the study interval, the overall incidence rate of postinjection endophthalmitis was 0.01% (1/8037). Antibiotic eye drops were prescribed after IVB injection for 2771 eyes (34.5%). The single case of acute endophthalmitis occurred after a resident-performed injection, and vitreous culture showed growth of Staphylococcus epidermidis. The incidence rate of acute endophthalmitis after resident-performed IVB injection was 0.02% (1/4921). No statistically significant difference was found in the rates of endophthalmitis between resident-performed and attending-performed injections (p = 1). Also, the difference in the rates of endophthalmitis between those receiving postinjection antibiotics and those who did not was not statistically significant (p = 0.3). CONCLUSIONS: The risk for endophthalmitis after resident-performed IVB injection is low and similar to that of the supervising surgeons performing the procedure.