Comparison of conjunctiva-related complications between scleral and corneal patch grafts in Ahmed glaucoma valve implantation

Purpose: Comparison of the conjunctiva related complication rates and success rates among eyes with Ahmed glaucoma valve (AGV) implantation in which eye bank derived scleral and corneal patch grafts had been used to cover the tube. Methods: Retrospective comparative study. Patients who underwent AGV implantation between January 2000 to December 2016 were included. Demographic, clinical data, intra and post operative data was obtained from electronic medical records. Conjunctiva related complications were divided into two groups: with and without implant exposure. Conjunctiva related complication rates, success rate, risk factors among eyes with corneal and scleral patch graft were compared. Results: Three hundred and twenty three eyes of 316 patients underwent AGV implantation. Scleral patch graft was used in 214 eyes of 210 patients (65.9%) and corneal patch graft was used in 109 eyes of 107 patients (34%). Median follow up was 14 months. There was no significant difference in the conjunctiva related complication rate (7.3 % in corneal patch graft versus 7.0% in scleral patch graft;p=0.5) and conjunctival dehiscence rate (3.7% versus 4.6%, P = 0.7) among the two groups. Success rate was significantly higher in the corneal patch graft group versus the scleral patch graft group (98% versus 72%; p=0.001). Eyes with corneal patch graft had a higher survival rate (P = 0.01). Conclusion: There was no significant difference in the rate of conjunctiva related complications following corneal and scleral patch grafts used to cover the AGV tube. Eyes with corneal patch graft had a higher success rate and survival rate.

Outcomes of medical and surgical management in eyes with idiopathic elevated episcleral venous pressure

Purpose: Idiopathic elevated episcleral venous pressure (IEEVP) is a rare cause of secondary glaucoma and is a diagnosis of exclusion. The aim of this study was to describe the clinical presentation and analyze the outcomes of medical and surgical management in eyes diagnosed with idiopathic elevated episcleral venous pressure. Methods: A retrospective analysis of eyes diagnosed with IEEVP over a 5?year period between April 2012 and March 2016 was performed. The demographic details, medical history, and clinical course of the cases were obtained from the medical records. Data pertaining to the severity of glaucomatous damage, response to medical management, need for surgical intervention, and their outcomes were analyzed. Results: Fifteen eyes of 13 patients were included. Thirteen eyes (86.6%) had open angle configuration. Among the 13 eyes that had glaucoma, eight eyes (61.5%) had severe glaucoma, four eyes (30.7%) had moderate glaucoma, and one eye (7.6%) had mild glaucoma. The median follow?up was 210 days. Seven of the 15 eyes (46.6%) required a glaucoma filtration procedure, and three underwent prophylactic sclerotomies. 71.4% of these eyes had complete success. One out of the seven operated eyes required choroidal drainage post?operatively. Conclusion: IEEVP is an extremely rare condition and presents with raised intra?ocular pressure and tortuous episcleral vessels. The management of IEEVP is similar to that of primary open angle glaucoma. Uveal effusion is to be anticipated, and hence, combining trabeculectomy with prophylactic sclerotomies is advisable.

Rectifying calibration error of Goldmann applanation tonometer is easy.

Purpose: Goldmann applanation tonometer (GAT) is the current Gold standard tonometer. However, its calibration error is common and can go unnoticed in clinics. Its company repair has limitations. The purpose of this report is to describe a self‑taught technique of rectifying calibration error of GAT. Materials and Methods: Twenty‑nine slit‑lamp‑mounted Haag‑Streit Goldmann tonometers (Model AT 900 C/M; Haag‑Streit, Switzerland) were included in this cross‑sectional interventional pilot study. The technique of rectification of calibration error of the tonometer involved cleaning and lubrication of the instrument followed by alignment of weights when lubrication alone didn’t suffice. We followed the South East Asia Glaucoma Interest Group’s definition of calibration error tolerance (acceptable GAT calibration error within ±2, ±3 and ±4 mm Hg at the 0, 20 and 60‑mm Hg testing levels, respectively). Results: Twelve out of 29 (41.3%) GATs were out of calibration. The range of positive and negative calibration error at the clinically most important 20‑mm Hg testing level was 0.5 to 20 mm Hg and ‑0.5 to ‑18 mm Hg, respectively. Cleaning and lubrication alone sufficed to rectify calibration error of 11 (91.6%) faulty instruments. Only one (8.3%) faulty GAT required alignment of the counter‑weight. Conclusions: Rectification of calibration error of GAT is possible in‑house. Cleaning and lubrication of GAT can be carried out even by eye care professionals and may suffice to rectify calibration error in the majority of faulty instruments. Such an exercise may drastically reduce the downtime of the Gold standard tonometer.

Ahmed glaucoma valve in eyes with preexisting episcleral encircling element.

Background: To describe the use of Ahmed glaucoma valve (AGV) in the management of intractable glaucoma in eyes with a preexisting episcleral encircling element. Materials and Methods: This is a retrospective, consecutive, noncomparative study. The study included 12 eyes of 12 patients with a preexisting episcleral encircling element that underwent implantation of silicone AGV to treat intractable glaucoma during January 2009 to September 2010. Results: The mean patient age was 25.6 (standard deviation 17.1) years. Five (41.6%) patients were monocular. The indications for AGV were varied. The mean duration between placement of episcleral encircling element and implantation of AGV was 30.5 (33.8) months. The mean follow-up was 37.4 (22.9) weeks. Preoperatively, the mean intraocular pressure (IOP) was 31.4 (7.9) mmHg and the mean antiglaucoma medications were 2.8. At the fi nal postoperative follow-up, the mean IOP was 12.5 (3.5) mmHg and the mean number of antiglaucoma medications was 0.8 (P < 0.001). The complications observed over the follow-up period did include corneal graft failure in three eyes, tube erosion in two eyes and rhegmatogenous retinal detachment in one eye. Conclusion: AGV is an eff ective option in the management of intractable glaucoma in eyes with a preexisting episcleral encircling element keeping in mind the possibility of signifi cant postoperative complications.

Prevalence and causes of low vision and blindness in an urban population: The Chennai Glaucoma Study.

Aim: To evaluate the prevalence and causes of low vision and blindness in an urban south Indian population. Settings and Design: Population-based cross-sectional study. Exactly 3850 subjects aged 40 years and above from Chennai city were examined at a dedicated facility in the base hospital. Materials and Methods: All subjects had a complete ophthalmic examination that included best-corrected visual acuity. Low vision and blindness were defined using World Health Organization (WHO) criteria. The influence of age, gender, literacy, and occupation was assessed using multiple logistic regression. Statistical Analysis: Chi-square test, t-test, and multivariate analysis were used. Results: Of the 4800 enumerated subjects, 3850 subjects (1710 males, 2140 females) were examined (response rate, 80.2%). The prevalence of blindness was 0.85% (95% CI 0.6–1.1%) and was positively associated with age and illiteracy. Cataract was the leading cause (57.6%) and glaucoma was the second cause (16.7%) for blindness. The prevalence of low vision was 2.9% (95% CI 2.4–3.4%) and visual impairment (blindness + low vision) was 3.8% (95% CI 3.2–4.4%). The primary causes for low vision were refractive errors (68%) and cataract (22%). Conclusions: In this urban population based study, cataract was the leading cause for blindness and refractive error was the main reason for low vision.

Long-term change in central corneal thickness from a glaucoma perspective.

Aim: To investigate the longitudinal change in central corneal thickness (CCT) over 3 years in patients with glaucoma. Materials and Methods: The Chennai Glaucoma Follow‑up Study, an offshoot of the Chennai Glaucoma Study, was designed to evaluate the progression of glaucoma. A cohort of participants in the Chennai Glaucoma Study that were suffering from glaucoma or were at a higher risk for glaucoma underwent comprehensive ophthalmic evaluation at the base hospital at 6‑month intervals during the years 2004 to 2007. The CCT (average of 10 readings) was measured between 11 am and 1 pm on any given day using an ultrasonic pachymeter. Patients with a history of ocular surgery, corneal disease and usage of topical carbonic anhydrase inhibitor were excluded. No patient was a contact lens wearer. Results: One hundred and ninety‑six patients (84 male, 112 female) met the inclusion criteria. We analyzed data from the right eye. The mean age of the patients was 59.97 ± 9.06 years. Fifty‑nine (30.1%) of the patients were diabetic. The mean change in CCT (CCT at first patient visit – CCT at last patient visit) was 3.46 ± 7.63 µm. The mean change in CCT was 0.75 µm per year (R2 = 0.00). Age, gender, intraocular pressure at the first patient visit and diabetic status had no significant influence on the magnitude of change in CCT. Conclusion: A carefully obtained CCT reading by a trained examiner need not be repeated for at least 3 years as long as the ocular and systemic factors known to affect the measurement of CCT are constant.

Management of complications in glaucoma surgery.

Surgical option for glaucoma is considered when other modalities are not working out to keep the intraocular pressure under control. Since the surgical procedures for glaucoma disrupt the integrity of the globe, they are known to produce various complications. Some of those complications can be vision-threatening. To minimize the morbidity, it is very important that one should know how to prevent them, recognize them and treat them. The objective of this article is to provide insight into some of those complications that will help the ophthalmologists in treating glaucoma patients in their clinical practice.

Importance of population-based studies in clinical practice.

In the last decade, there have been reports on the prevalence of glaucoma from the Vellore Eye Survey, Andhra Pradesh Eye Diseases Survey, Aravind Comprehensive Eye Survey, Chennai Glaucoma Study and West Bengal Glaucoma Study. Population-based studies provide important information regarding the prevalence and risk factors for glaucoma. They also highlight regional differences in the prevalence of various types of glaucoma. It is possible to gather important insights regarding the number of persons affected with glaucoma and the proportion with undiagnosed disease. We reviewed the different population-based studies from India and compare their findings. The lacunae in ophthalmic care that can be inferred from these studies are identified and possible reasons and solutions are discussed. We also discuss the clinical relevance of the various findings, and how it reflects on clinical practice in the country. Since India has a significantly high disease burden, we examine the possibility of population-based screening for disease in the Indian context.

The Chennai glaucoma study: Prevalence and risk factors for glaucoma in cataract operated eyes in urban Chennai.

We report the prevalence and risk factors for glaucoma among aphakes and pseudophakes in 3850 subjects who participated in a population-based study in urban south India. The subjects underwent an ophthalmic examination including applanation tonometry, gonioscopy, optic disc evaluation and frequency doubling perimetry. Glaucoma was diagnosed using the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) criteria. Thirty eight, 15 aphakes and 23 pseudophakes (0.99% of 3850 subjects) of the 406 persons who had undergone cataract surgery were diagnosed with glaucoma. Aphakes/pseudophakes were at higher risk of glaucoma as compared to the phakic population (Odds Ratio: 2.71, 95% CI: 1. 94, 3.38, p=0.001). On multivariate analysis, older age and higher intra ocular pressure were risk factors for glaucoma. Blindness attributable to glaucoma was detected in 20% of aphakic and 4.3% of pseudophakic eyes. Glaucoma was a significant cause of morbidity in those who had undergone cataract surgery in this urban population.

Outcomes of cataract surgery in a rural and urban south Indian population.

Purpose: To assess the visual outcome after cataract surgery in a south Indian population. Materials and Methods: Population-based cross-sectional study of subjects aged 40 years or more. Three thousand nine hundred and twenty-four rural subjects from 27 contiguous villages and 3850 urban subjects from five randomly selected divisions were studied. All subjects underwent a comprehensive ophthalmic examination that included visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, and dilated retinal examination. Statistical Analysis: Chi square test, t test and multivariate analysis were used. Results: Five hundred and twenty-eight (216 males, 312 females, 781 eyes) rural subjects (13.5%, 95% confidence interval (CI) 12.4% to 14.6%) and 406 (197 males, 209 females, 604 eyes) urban subjects (10.5%, 95% CI 9.6-11.5%) had undergone cataract surgery. Outcome of cataract surgery was defined based on visual acuity. Using best-corrected visual acuity for classification, the single most important cause for visual impairment was cystoid macular edema in the aphakic group and posterior capsule opacification in the pseudophakic group. Aphakia (visual acuity of <20/60 to ≤20/400 - odds ratio (OR) 1.8; 95% CI 1.3 to 2.6%, visual acuity of <20/400 - OR 6.2; 95% 4.0 to 9.8%), rural residence (visual acuity of <20/60 to ≤20/400 - OR 3.2; 95% CI 2.2 to 4.5% and visual acuity of <20/400 - OR OR 3.5; 95% CI 2.3 to 5.5%) were associated with visual impairment. The urban cataract-operated population had significantly more pseudophakics (P < 0.001), men (P = 0.02) and literates (P < 0.001). In the rural group the prevalence of cataract surgery (13.5% vs. 10.5%, P < 0.001) and number of people that had undergone cataract surgery within three years prior to examination (P < 0.001) were significantly greater. In 30% of rural and 16% of urban subjects uncorrected refraction was the cause of visual impairment. Conclusions: Surgery-related complications were major causes for visual acuity of <20/60.

Peribulbar anesthesia for cataract surgery: Effect of lidocaine warming and alkalinization on injection pain, motor and sensory nerve blockade.

Aim: To compare self-reported pain and efficacy of warmed, alkalinized, and warmed alkalinized lidocaine with plain 2% lidocaine at room temperature for peribulbar anesthesia in cataract surgery. Materials and Methods: Through a prospective, single-blinded, randomized, controlled clinical trial 200 patients were divided into four groups. They received either lidocaine at operating room temperature 18°C, control group (Group C), lidocaine warmed to 37°C (Group W), lidocaine alkalinized to a pH of 7.09 ± 0.10 (Group B) or lidocaine at 37°C alkalinized to a pH of 6.94 ± 0.05 (Group WB). All solutions contained Inj. Hyaluronidase 50 IU/ml. Pain was assessed using a 10-cm visual analog score scale. Time of onset of sensory and motor blockade and time to onset of postoperative pain were recorded by a blinded observer. Results: Mean pain score was significantly lower in Group B and WB compared with Group C (P < 0.001). Onset of analgesia was delayed in Group C compared with Group B (P = 0.021) and WB (P < 0.001). Mean time taken for the onset of complete akinesia and supplementation required for the block was significantly lower in Group B. Time of onset of pain after operation was significantly earlier in Group W compared with Group C (P = 0.036). Conclusion: Alkalinized lidocaine with or without warming produced less pain than lidocaine injected at room temperature. Alkalinization enhances the effect of warming for sensory nerve blockade, but warming does not enhance alkalinization, in fact it reduces the efficacy of alkalinized solution for blocking the motor nerves in the eye.

Comparison of Humphrey MATRIX and Swedish interactive threshold algorithm standard strategy in detecting early glaucomatous visual field loss.

Purpose: The aim of this study was to compare the Humphrey MATRIX visual field (frequency doubling technology threshold) and Swedish interactive threshold algorithm (SITA) standard strategy white on white perimetry in detecting glaucomatous visual field loss. Material and Methods: Twenty-eight adult subjects, diagnosed to have glaucoma at a tertiary eye care hospital, who fulfilled the inclusion criteria, were included in this prospective study. All subjects underwent a complete ophthalmic examination. Subjects with glaucomatous optic disc changes underwent repeat perimetric examination on the same day with the Humphrey visual field analyzer (HFA II) and Humphrey MATRIX, the order of testing being random. Only reliable fields, where the HFA results corresponded to the disc changes were considered for analysis. A cumulative defect depth in each hemifield in both HFA and MATRIX reports was calculated. Results: Thirty-seven eyes of 24 subjects had reliable fields corresponding to optic disc changes. The mean age of the subjects was 56 +/- 12 years. There were 12 males and 12 females. The test duration was significantly less on the MATRIX, mean difference in test duration was -81 +/- 81.3 sec ( p p = 0.55, p = 0.64 respectively) and a positive correlation coefficient of 0.63 and 0.72 respectively. Poor agreement was found with the glaucoma hemifield test. Conclusion: The Humphrey MATRIX takes less time in performing the test than SITA Standard and shows good correlation for mean deviation and pattern standard deviation. However, the glaucoma hemifield test showed poor agreement. The Humphrey MATRIX diagnoses were similar to established perimetric standards.

Agreement between two Goldmann type applanation tonometers.

The aim of the study was to assess agreement between two commercially available applanation tonometers for the measurement of intraocular pressure (IOP). Forty subjects underwent IOP measurement on two accurately calibrated Goldmann type applanation tonometers (Zeiss AT 030 (GATZ) and Inami L-5110(GATI)). The order of examination was randomized and observers were masked to the IOP recorded. The mean of two consecutive readings, from a randomly selected eye for each subject, was used for analysis. Agreement was assessed using the Altman and Bland plot. The mean (SD) IOP readings on GATZ was 15.32 (+/-6.80) mm Hg and on GATI was 13.52 (+/-5.65) mm Hg (p< 0.001, 95% CI of the difference: -2.48 to -1.11). The 95% limits of agreement on the Altman and Bland plot were:-2.47 to 6.16 mm Hg). There was significant inter-instrument variability between the two accurately calibrated Goldmann type applanation tonometers studied.

Comparison of refractive errors and factors associated with spectacle use in a rural and urban South Indian population.

Purpose: To compare the prevalence of refractive errors and factors associated with spectacle use in a rural and urban south Indian population. Materials and Methods: Four thousand eight hundred subjects (age> 39 years) each from rural and urban Tamil Nadu were enumerated for a population-based study. All participants underwent a complete ophthalmic evaluation including best-corrected visual acuity (BCVA), objective and subjective refraction. Out of 3924 rural responders 63.91% and out of 3850 urban responders 81.64% were phakic in the right eye with BCVA of 20/40 or better and were included in the study. Association of spectacle use and refractive errors with different parameters were analysed using logistic regression. Statistical Analysis: Chi square, t test, Chi square for trend and Pearson's correlation coefficient were used for analysis. Results: Spectacle use was significantly higher and positively associated with literacy and employment in the urban population. The age and gender-adjusted prevalence of emmetropia, myopia of spherical equivalent (SE) </=-0.50 diopter sphere (DS), high myopia (SE </=-5.00DS), hyperopia (SE> 0.50DS) and astigmatism ≤ 0.50 diopter cylinder (DC) were 46.8%, 31.0%, 4.3%, 17.9% and 60.4% respectively in the rural population and 29.0%, 17.6%, 1.5%, 51.9%, 59.1% respectively in the urban population. The prevalence of emmetropia decreased with age ( p p = 0.001) and were associated with nuclear sclerosis ( p = 0.001) in both populations. Hyperopia was commoner among women than men ( p = 0.001); was positively associated with diabetes mellitus ( p = 0.008) in the rural population and negatively with nuclear sclerosis ( p = 0.001) in both populations. Conclusion: Spectacle use was found to be significantly lower in the rural population. The pattern of refractive errors was significantly different between both populations.

Retinal nerve fiber layer measurements in indian eyes using the scanning laser polarimeter, GDx.

PURPOSE: To obtain retinal nerve fiber layer (RNFL) measurements in normal Indian subjects of different age groups; and to determine the differences between the right and the left eye of a subject and variations between male and female gender using the scanning laser polarimeter GDx. MATERIALS AND METHODS: Prospective cross-sectional study of 180 eyes of 94 subjects. The RNFL values were obtained with the nerve fiber analyser GDx using default quadrant positions supplied by the manufacturer. Fourteen parameters were studied. Of these 6 were average-based parameters (average thickness, superior maximum, inferior maximum, ellipse average, superior average, inferior average), 4 ratio-based parameters (symmetry, superior ratio, inferior ratio, superior/nasal), 4 "other" parameters (maximum modulation, number, ellipse modulation, superior integral). The main outcome measures were effect of age on RNFL values, comparison of males and females and the right and the left eye of a subject. RESULTS: There was a negative linear correlation with age. Three ratio-based parameters showed a statistically significant negative correlation with age. "Number" increased with age. Superior maximum, superior average, superior integral, symmetry and superior ratio were higher for the left eye. 'Number' was higher for the right eye. Superior ratio and maximum modulation were more in females than males, no difference was noted with other parameters. CONCLUSION: There was a gradual decrease of RNFL values with increasing age - the superior quadrant values were higher for the left eye than the right eye, suggesting asymmetry. No significant differences were detected between males and females.