Vishal Arora

Repeatability and Agreement of Three Scheimpflug-Based Imaging Systems for Measuring Anterior Segment Parameters in Keratoconus

PURPOSE To assess the repeatability and agreement of three rotating Scheimpflug cameras, Pentacam, Galilei, and Sirius, in measuring the mean keratometry (Km), thinnest corneal thickness (TCT), anterior chamber depth (ACD), and mean posterior keratometry (pKm) in keratoconus patients in a prospective study. METHODS Fifty-five eyes of 55 patients with keratoconus underwent three consecutive scans on each machine, performed by a single operator. Within-subject standard deviation (Sw), test-retest repeatability (TRT), and coefficient of variation (COV) for assessing repeatability and Bland-Altman plots for the agreement between the mean measurements of each machine were examined. RESULTS The Sw of Km and pKm measurements with Pentacam (0.23 and 0.10 diopters [D], respectively) were significantly lower (better) than those of Galilei (0.60 and 0.17) and Sirius (0.23 and 0.36). The Sw of TCT measurements with Sirius (8.88 μm) was significantly lower than that of Galilei (11.64 μm). The COV ranged between 0.5 for the Km measurements of Pentacam and 2.8 for the TCT measurements of Galilei. Significant proportional bias in agreement was detected for the pKm measurements with all the three device pairs and for the ACD measurements between Pentacam and Galilei and between Galilei and Sirius. CONCLUSIONS Though Pentacam, Galilei, and Sirius showed repeatable measurements for Km, TCT, ACD, and pKm, repeatabilities with Pentacam and Sirius were better than those with Galilei. There were significant differences in the measurements between the three devices; hence they cannot be used interchangeably for anterior segment measurements in keratoconus patients.

Microscope Integrated Intraoperative Spectral Domain Optical Coherence Tomography for Cataract Surgery: Uses and Applications

Abstract Aim: To demonstrate the uses and applications of a microscope integrated intraoperative Optical Coherence Tomography in Micro Incision Cataract Surgery (MICS) and Femtosecond Laser Assisted Cataract Surgery (FLACS). Methods: Intraoperative real time imaging using the RESCAN™ 700 (Carl Zeiss Meditec, Oberkochen, Germany) was done for patients undergoing MICS as well as FLACS. The OCT videos were reviewed at each step of the procedure and the findings were noted and analyzed. Results: Microscope Integrated Intraoperative Optical Coherence Tomography was found to be beneficial during all the critical steps of cataract surgery. We were able to qualitatively assess wound morphology in clear corneal incisions, in terms of subclinical Descemet’s detachments, tears in the inner or outer wound lips, wound gaping at the end of surgery and in identifying the adequacy of stromal hydration, for both FLACS as well as MICS. It also enabled us to segregate true posterior polar cataracts from suspected cases intraoperatively. Deciding the adequate depth of trenching was made simpler with direct visualization. The final position of the intraocular lens in the capsular bag and the lack of bioadhesivity of hydrophobic acrylic lenses were also observed. Conclusions: Even though Microscope Integrated Intraoperative Optical Coherence Tomography is in its early stages for its application in cataract surgery, this initial assessment does show a very promising role for this technology in the future for cataract surgery both in intraoperative decision making as well as for training purposes.

Current review and a simplified "five-point management algorithm" for keratoconus

Keratoconus is a slowly progressive, noninflammatory ectatic corneal disease characterized by changes in corneal collagen structure and organization. Though the etiology remains unknown, novel techniques are continuously emerging for the diagnosis and management of the disease. Demographical parameters are known to affect the rate of progression of the disease. Common methods of vision correction for keratoconus range from spectacles and rigid gas-permeable contact lenses to other specialized lenses such as piggyback, Rose-K or Boston scleral lenses. Corneal collagen cross-linking is effective in stabilizing the progression of the disease. Intra-corneal ring segments can improve vision by flattening the cornea in patients with mild to moderate keratoconus. Topography-guided custom ablation treatment betters the quality of vision by correcting the refractive error and improving the contact lens fit. In advanced keratoconus with corneal scarring, lamellar or full thickness penetrating keratoplasty will be the treatment of choice. With such a wide spectrum of alternatives available, it is necessary to choose the best possible treatment option for each patient. Based on a brief review of the literature and our own studies we have designed a five-point management algorithm for the treatment of keratoconus.

Evaluation of Major Depressive Disorder in Patients Receiving Chronic Treatment with Topical Timolol

Purpose: It was the aim of this study to evaluate the prevalence of major depressive disorder (MDD) in chronic glaucoma patients on a topical β-blocker (timolol). Design: An observational case control study was performed. Methods: The subjects recruited were divided into 3 groups. Group I included 98 patients with chronic glaucoma on topical β-blocker therapy, group II included 64 chronic glaucoma patients on prostaglandin analogues, and group III included 150 normal controls. All subjects were screened for MDD by the self-administered questionnaire Prime-MD Today (Primary Care Evaluation of Mental Disorders, New York, N.Y., USA). Results: The control group had a significantly higher age (p < 0.001) compared to the glaucoma patients on timolol or prostaglandin analogues; 9/98 patients (9.2%) on timolol, 1/64 patients (1.5%) on prostaglandins and 3/150 (2%) control subjects were screened positive for MDD. The odds ratios adjusted for age, sex and duration of glaucoma showed that patients on β-blocker therapy were 6.4 and 4.9 times more likely to have depression compared to those on prostaglandin analogues and control subjects, respectively. Conclusions: Glaucoma patients on topical timolol should be screened for depression and referred for appropriate psychiatric consultation and treatment if indicated.

Diurnal versus office-hour intraocular pressure fluctuation in primary adult onset glaucoma

PURPOSE To evaluates the role of measuring intraocular pressure (IOP) outside office-hour in primary adult onset glaucoma. METHODS This retrospective study included 100 cases of primary adult onset glaucoma. IOP readings obtained with Goldmann applanation tonometry between 7 am and 10 pm were compared to office-hour readings. RESULTS One hundred patients were enrolled (mean age: 58.64 ± 10.98 years) in the study. Overall, mean diurnal IOP was significantly higher than mean office IOP (p < 0.05). Two-thirds of the patients had peak IOP measurements outside office-hour. Mean diurnal IOP fluctuation (7.03 ± 2.69 mm Hg) was significantly higher than mean office IOP fluctuation (4.31 ± 2.6 mm Hg) (p < 0.003). There was a significant correlation between baseline IOP and fluctuation in IOP (r = 0.61, p<0.001). CONCLUSION The mean diurnal IOP and IOP fluctuations were higher than office-hour readings in patients with primary adult onset glaucoma. Diurnal monitoring may be particularly useful in patients with high baseline IOP.

Intraoperative Optical Coherence Tomography Using the RESCAN 700: Preliminary Results in Collagen Crosslinking

Purpose. To compare the penetration of riboflavin using a microscope-integrated real time spectral domain optical coherence tomography (ZEISS OPMI LUMERA 700 and ZEISS RESCAN 700) in keratoconus patients undergoing accelerated collagen crosslinking (ACXL) between epithelium on (epi-on) and epithelium off (epi-off). Methods. Intraoperative images were obtained during each of the procedures. Seven keratoconus patients underwent epi-on ACXL and four underwent epi-off ACXL. A software tool was developed using Microsoft.NET and Open Computer Vision (OpenCV) libraries for image analysis. Pre- and postprocedure images were analyzed for changes in the corneal hyperreflectance pattern as a measure of the depth of riboflavin penetration. Results. The mean corneal hyperreflectance in the epi-on group was 12.97 ± 1.49 gray scale units (GSU) before instillation of riboflavin and 14.46 ± 2.09 GSU after AXCL (P = 0.019) while in the epi-off group it was 11.43 ± 2.68 GSU and 16.98 ± 8.49 GSU, respectively (P = 0.002). The average depth of the band of hyperreflectance in the epi-on group was 149.39 ± 15.63 microns and in the epi-off group it was 191.04 ± 32.18 microns. Conclusion. This novel in vivo, real time imaging study demonstrates riboflavin penetration during epi-on and epi-off ACXL.

Impact of initial topical medical therapy on short-term quality of life in newly diagnosed patients with primary glaucoma

Purpose: To evaluate the impact of initial topical medical therapy on newly diagnosed glaucoma patients using the Indian Vision Function Questionnaire (IND-VFQ33). Patients and Methods: The IND-VFQ33 was used to evaluate the quality of life (QoL) in 62 newly diagnosed patients with moderate to severe primary glaucoma and 60 healthy controls. IND-VFQ33 is a 33 item QoL assessment tool with three domains: General functioning, psychosocial impact and visual symptoms. The glaucoma patients were started on medical therapy and the QoL assessment was repeated after 3 months. Results: Glaucoma patients (mean age: 55.6 ± 9.6 years, range 40–77 years) and controls (mean age: 54.9 ± 6.7 years, 42–73 years) were matched with respect to age (P = 0.72), gender (P = 0.91) and literacy (P = 0.18). Glaucoma patients had significantly worse QoL as compared to controls at baseline across all the three domains (P < 0.001). 3 months after initiation of treatment, the overall QoL life significantly worsened from baseline with a decrease in general functioning (P < 0.001) and psychosocial impact (P = 0.041). Visual acuity in better eye significantly co-related to poor QoL at baseline (P < 0.001) and at 3 months (P = 0.04). In addition, the use of >2 topical medications significantly co-related to poor QoL at 3 months (P = 0.01). Conclusions: Evaluation using the IND-VFQ33 revealed that newly diagnosed glaucoma patients have a significant worsening of QoL after initiation of topical ocular hypotensive therapy. This should be an important consideration when educating patients about the disease and its therapy.

Evaluation of the effect of scleral buckling on the anterior chamber angle using ASOCT.

Purpose:To evaluate the change in anterior chamber angle parameters after scleral buckling surgery using anterior segment optical coherence tomography (ASOCT). Methods:Fifty-five phakic eyes of 55 subjects undergoing scleral buckling with the placement of an encircling band for primary rhegmatogenous retinal detachment were included in this study. Anterior chamber angle assessment was performed using ASOCT. The trabecular iris angle (TIA), the angle-opening distance, and the trabecular iris space area were the parameters obtained preoperatively and 48 hours, 1 week, and 1 month after the surgery using ASOCT. The intraocular pressure (IOP) was measured using Goldmann applanation tonometry. Results:The mean age of the patients was 43.2±11.3 years; there were 38 male and 17 female patients. There was a significant decrease in all the angle parameters (TIA, angle opening distance, and trabecular iris space area) at 48 hours, 1 week, and 1 month after surgery (P<0.0001). TIA 180 degree decreased from 41.93±14.27 degrees preoperatively to 31.09±10.52 degrees (P<0.0001) and TIA 0 degree from 42.7±14.04 degrees to 32.92±12.17 degrees (P<0.0001) at 48 hours postoperatively. The mean IOP at 48 hours (17.04±3.26 mm Hg) was significantly higher than the preoperative level (12.68±1.96 mm Hg; P<0.001). No significant difference was noted between the mean preoperative IOP and the IOP readings at 1 week (P=0.402) and 1 month (P=0.23) postoperatively. Conclusions:ASOCT imaging reveals that scleral buckling surgery for retinal detachment induces significant narrowing of the anterior chamber angle.