Syril Dorairaj

In Vivo Evaluation of Focal Lamina Cribrosa Defects in Glaucoma

OBJECTIVES To assess focal lamina cribrosa (LC) defects in glaucoma using enhanced depth imaging optical coherence tomography and to investigate their spatial relationships with neuroretinal rim and visual field loss. METHODS Serial horizontal and vertical enhanced depth imaging optical coherence tomographic images of the optic nerve head were obtained from healthy subjects and those with glaucoma. Focal LC defects defined as anterior laminar surface irregularity (diameter, >100 μm;depth, >30 μm) that violates the normal smooth curvilinear contour were investigated regarding their configurations and locations. Spatial consistency was evaluated among focal LC defects, neuroretinal rim thinning/notching, and visual field defects. RESULTS Forty-six healthy subjects (92 eyes) and 31 subjects with glaucoma (45 eyes) were included. Ninety-eight focal LC defects representing various patterns and severity of laminar tissue loss were found in 34 eyes with glaucoma vs none in the healthy eyes. Seven of 11 eyes with glaucoma with no visible focal LC defect had a deeply excavated optic disc with poor LC visibility. Eleven focal LC defects presented clinically as an acquired pit of the optic nerve, and the others as neuroretinal rim thinning/notching. Focal LC defects preferably occurred in the inferior/inferotemporal far periphery of the LC including its insertion. Eyes with focal LC defects limited to the inferior half of the optic disc had greater sensitivity loss in the superior visual hemifield and vice versa. CONCLUSIONS Mechanisms of LC deformation in glaucoma include focal loss of laminar beams, which may cause an acquired pit of the optic nerve in extreme cases.Focal LC defects occur in tandem with neuroretinal rim and visual field loss.

Comparisons of anterior segment biometry between Chinese and Caucasians using anterior segment optical coherence tomography

Purpose To compare anterior segment parameters between eyes of Chinese and Caucasians using anterior segment optical coherence tomography and to evaluate the association between these parameters and anterior chamber angle width between the two ethnic groups. Methods 60 Chinese and 60 Caucasians, 30 with open angles and 30 with narrow angles (defined as Shaffer grade ≤2 in ≥3 quadrants during dark room gonioscopy) in each group, were consecutively enrolled. One eye of each subject was randomly selected for imaging in a completely darkened room. Measurements, including anterior chamber depth (ACD), scleral spur-to-scleral spur distance (anterior chamber width (ACW)), anterior chamber angle width, iris convexity and iris thickness, were compared between the groups. The associations between angle opening distance and biometric measurements were evaluated with univariate and multivariate regression analyses. Results There were no differences in age, axial length, anterior chamber angle measurements, pupil diameter and iris convexity between Chinese and Caucasians in both open-angle and narrow-angle groups. However, the ACD and ACW were smaller and the iris was thicker in Chinese. In the multivariate analysis, the ACD was the most influential biometric parameter for angle opening distance in both Chinese and Caucasians. After adjusting the effects of axial length, age and sex, ACD and ACW were significantly smaller in Chinese. Conclusions Chinese eyes had smaller ACD, smaller ACW and greater iris thickness than Caucasians. ACD was the most influential parameter in determining the angle width in both ethnic groups.

Dynamic Analysis of Iris Configuration with Anterior Segment Optical Coherence Tomography

PURPOSE To evaluate dynamic changes in iris configuration and their association with anterior chamber angle width by using anterior segment optical coherence tomography (ASOCT). METHODS Forty-six normal subjects with open angles and 40 with narrow angles (Shaffer grade < or =2 in three or more quadrants during dark room gonioscopy) were analyzed. The dynamic ASOCT dark-light changes of iris bowing were captured with real-time video recording and nasal iris bowing, nasal anterior chamber angle, and pupil diameter were measured in serial image frames selected from the video capture. The associations between iris bowing, iris thickness, anterior chamber depth (ACD), age, anterior chamber angle, and pupillary diameter measurements were evaluated with univariate and multivariate regression analyses. RESULTS The relationship between iris bowing and pupil diameter was largely linear, with three dynamic patterns observed: (1) convex-to-convex (iris remains convex in dark and light); (2) concave-to-convex (iris changes from concave to convex from light to dark); and (3) concave-to-concave (iris remains concave in dark and light). All the subjects with narrow angles had convex-to-convex anatomy, although 43% of the subjects with open angles also demonstrated this pattern. These individuals were older and had shorter axial length (both with P < 0.001). Older age (r = -0.352, P = 0.001), smaller ACD (r = 0.382, P < 0.001), and smaller difference in angle opening distance in light and dark (r = 0.472, P < 0.001) were associated with smaller differences in iris bowing in the light and dark. ACD and iris bowing were independently associated with anterior chamber angle width. CONCLUSIONS Independent of ACD, iris bowing is an important biometric parameter that determines angle width. Investigation of iris dynamics may offer a new perspective in understanding the risk and mechanism of primary angle closure.

Comparative Evaluation of Suture-assisted and Fibrin Glue–assisted Scleral Fixated Intraocular Lens Implantation

PURPOSE To compare the visual outcomes and complications after suture-assisted and fibrin glue-assisted scleral fixated intraocular (IOL) implantation. METHODS Scleral fixated IOL implantation was performed in patients with inadequate capsular support. Intraocular lens fixation was achieved using sutures or fibrin glue. Main parameters evaluated were visual outcomes and complications. RESULTS Fifty patients were included in the study (n=25 suture, n=25 glue). The most common indication for scleral fixated IOL implantation was cataract surgery complicated with posterior capsule rupture (29/50 [58%]). No significant differences were noted between demographic characteristics, surgical indications, and preoperative corrected distance visual acuity (CDVA) in either group (P=.680). No intraoperative complications related to IOL fixation were encountered in any case. At last follow-up (6 months), CDVA was 20/40 or better in 88% and 84% of patients in the suture and glue groups, respectively. Postoperative inflammation (48% vs 16%) and glaucoma (40% vs 16%) were seen more frequently in eyes with sutures as compared to eyes with glue. Overall, a significantly higher number of complications were encountered in eyes with suture fixation (14/25 [56%]) compared to eyes with glue fixation (7/25 [28%]) (P=.045). CONCLUSIONS Although visual outcomes were similar at the end of 6 months in eyes that underwent suture- and glue-assisted scleral fixated IOL implantation, fibrin glue was associated with fewer complications.

Baerveldt glaucoma implant insertion in the posterior chamber sulcus

Aim: To report the clinical outcome of a surgical technique for insertion of the silicone tube of a Baerveldt glaucoma implant (BGI) in the posterior chamber sulcus. Methods: Non-comparative, interventional case series. Eight eyes of eight patients, with a follow-up of at least 18 months, who underwent insertion of a BGI with the silicone tube placed in the posterior chamber sulcus between 1998 and 2005 were included. Control of intraocular pressure (IOP), number of pressure-lowering medications, visual acuity and surgical complications were recorded. Results: Eight eyes of eight patients (mean (range) age 76.4 (62–94) years) were included in the study. The IOP was reduced from a preoperative mean (SD) of 28.2 (14.4) to 12.6 (5.8) mm Hg at 18 months. The mean (SD) number of preoperative medications for IOP control was reduced from 2.8 (1.5) to 1.3 (1.5) medications in the same period. No complications were observed during surgery or follow-up. Conclusion: Placement of the silicone tube in the posterior chamber sulcus is a safe and effective alternative technique for IOP control in patients with pseudophakia. Sulcus placement may reduce the likelihood of corneal endothelial loss and avoid the need for pars-plana vitrectomy and posterior segment tube insertion in complicated eyes.

Macular pigment optical density measured by dual-wavelength autofluorescence imaging in diabetic and nondiabetic patients: a comparative study.

PURPOSE To compare macular pigment optical density (MPOD) in type 2 diabetic and nondiabetic patients by using dual-wavelength autofluorescence imaging and to investigate the correlation of MPOD with glycosylated hemoglobin (HbA1C) and serum lipid levels. METHODS Forty-three patients were divided into groups 1 (controls, n = 14), 2 (diabetic without retinopathy, n = 17), and 3 (diabetic with mild nonproliferative retinopathy, n = 12). MPOD was measured with a modified confocal scanning laser ophthalmoscope and compared among groups (analysis of variance). The correlation of HbA1C and serum lipid (HDL, LDL, total cholesterol, and triglycerides) levels with MPOD was determined for each group (linear regression analysis). RESULTS Mean ± SD ages in groups 1 (56.2 ± 11.7 years), 2 (58.6 ± 11.5 years), and 3 (62.8 ± 9.8 years) were similar (P = 0.324). Mean MPOD averaged in a 2°-diameter circle around the fovea was significantly different between the three groups: 1, (0.29 ± 0.07 density units [DU]), 2 (0.22 ± 0.09 DU), and 3 (0.14 ± 0.05 DU) (P < 0.001). There was a significant difference in mean MPOD levels at 0.5° between groups 1 (0.51 ± 0.12 DU) and 2 (0.24 ± 0.11 DU; P < 0.001), but not between groups 2 and 3 (0.33 ± 0.15 DU; P > 0.05). A significant inverse correlation was observed between HbA1C levels and mean MPOD, averaged at 2° around the fovea in all patients (r = -0.63, P < 0.001). No significant correlations were found between MPOD and serum lipid levels or age. CONCLUSIONS Type 2 diabetic patients, with or without retinopathy, had reduced MPOD when compared with that in nondiabetic patients. In addition, a significant inverse correlation between MPOD and HbA1C levels was observed.

Ocular decompression retinopathy: A review

Ocular decompression retinopathy (ODR) presents as retinal hemorrhages following acute lowering of the intraocular pressure (IOP). We review 32 articles published from 1992 to 2011 and address the pathogenesis, clinical features, management, and outcomes of ODR. ODR is defined as a multifocal hemorrhagic retinopathy that results from acute lowering of IOP and is not explained by another process. Hemorrhages occur in all retinal layers, and most patients are asymptomatic. The mean drop in IOP in ODR is 33.2 ± 15.8 mm Hg (range, 4-57 mm Hg). Eighty-two percent are diagnosed by the first postoperative day, all within 2 weeks. ODR resolved in a mean of 13 ± 12.4 weeks (range, 2-72 weeks). Vitrectomy was required for vitreous and subhyaloid hemorrhage in 14% of cases. Visual outcomes are generally good, with 85% of eyes returning to baseline vision. Although ODR infrequently results in significant ocular morbidity, gradual reduction in IOP might prevent this complication.

Anterior segment imaging in glaucoma: An updated review

Anterior segment imaging allows for an objective method of visualizing the anterior segment angle. Two of the most commonly used devices for anterior segment imaging include the anterior segment optical coherence tomography (AS-OCT) and the ultrasound biomicroscopy (UBM). AS-OCT technology has several types, including time-domain, swept-source, and spectral-domain-based configurations. We performed a literature search on PubMed for articles containing the text “anterior segment OCT,” “ultrasound biomicroscopy,” and “anterior segment imaging” since 2004, with some pertinent references before 2004 included for completeness. This review compares the advantages and disadvantages of AS-OCT and UBM, and summarizes the most recent literature regarding the importance of these devices in glaucoma diagnosis and management. These devices not only aid in visualization of the angle, but also have important postsurgical applications in bleb and tube imaging.

Early outcomes of primary pediatric keratoplasty in patients with acquired, atraumatic corneal pathology

PURPOSE To evaluate the early outcomes of pediatric corneal transplantation in patients with acquired, nontraumatic corneal pathology. METHODS In this retrospective series, the records of children 15 years of age or younger who underwent optical penetrating keratoplasty for acquired nontraumatic corneal pathologies between December 2008 and June 2010 were reviewed. Demographic features, etiology of opacification, visual acuity, and other clinical findings were recorded. RESULTS Nineteen eyes of 19 children (10 females) were included. Mean age at time of surgery was 9.1 ± 3.01 years (range, 5-15 years). Adherent leukoma secondary to healed infectious keratitis (n = 12, 63%) and keratoconus (n = 7, 37%) were the leading indications for surgery. The mean follow-up period was 10.2 ± 3.3 months (range, 6-18 months). Postoperatively, clear grafts were seen in 15 cases (79%). Graft failure was noted in 4 eyes secondary to allograft rejection (n = 1), graft infection (n = 1), primary graft failure (n = 1), and uncontrolled glaucoma (n = 1). The most common cause of moderate or poor visual outcome was amblyopia (80%). Overall, 13 patients (68%) had postoperative visual acuity better than the preoperative vision. CONCLUSIONS Penetrating keratoplasty can yield good anatomic results in children with acquired, nontraumatic causes of corneal scarring, but amblyopia limits the visual outcomes.

Prevalence and Etiology of Amblyopia in Southern India: Results from Screening of School Children Aged 5-15 years

Abstract Purpose: To determine the prevalence and etiology of amblyopia in school children. Methods: A total of 4020 school children aged between 5 and 15 years were screened in a population-based, cross-sectional study. Best corrected visual acuity and detailed ophthalmic evaluation were performed in all participants. Amblyopia associated with degraded visual input due to high refractive error was labeled ametropic amblyopia. Anisometropic amblyopia was diagnosed in participants with interocular refractive error difference ≥1 diopter. Strabismic amblyopia included that due to conflicting visual inputs between the eyes due to squint. Stimulus deprivation amblyopia was defined as amblyopia due to obstruction of the visual axis. Results: Prevalence of amblyopia was 1.1% (n = 44). The number of boys with amblyopia (n = 25, 57%) was slightly higher than the number of girls with amblyopia (n = 19, 43%; p = 0.6). A total of 28 (63.7%) children had mild to moderate amblyopia, whereas 16 (36.3%) had severe amblyopia. Underlying amblyogenic causes were ametropia (50%), anisometropia (40.9%), strabismus (6.8%), visual deprivation (4.5%) and combined causes (2.2%). No statistically significant difference was noted in the prevalence of amblyopia between rural (1.2%) and urban (0.9%) children (p = 0.5). Conclusion: In this study, the prevalence of amblyopia was 1.1% of the school children. Ametropia and anisometropia were the most common causes of amblyopia. We did not find any significant difference in amblyopia prevalence between rural and urban school children.