Comparison of Scleral Tono-Pen Intraocular Pressure Measurements with Goldmann Applanation Tonometry.

SIGNIFICANCE: Measuring the intraocular pressure (IOP) on the sclera can be an alternative to conventional corneal measurement in eyes with scarred corneas. However, these measurements have to be evaluated prior in normal eyes. Our study aimed to evaluate scleral IOP using Tono-Pen and compared it with corneal Goldmann applanation measurements. PURPOSE: The aim of this study was to evaluate the ability of limbal and scleral Tono-Pen IOP readings to predict central corneal Goldmann applanation tonometry (GAT) readings in eyes with normal corneas. METHODS: In a cross-sectional study, 115 eyes of 115 patients attending a tertiary eye care center underwent GAT on the central cornea followed by Tono-Pen readings at the central cornea, at the limbus, and at the sclera. Bland-Altman plots were used to determine the agreement between different methods of IOP measurement. RESULTS: The median IOP (interquartile range) by GAT performed on the central cornea was 18 (16, 24) mmHg, and the IOP ranged from 10 to 54 mmHg. The median IOPs (interquartile range) by Tono-Pen obtained at central cornea, limbus, and sclera were 16 (13, 23), 23 (17, 28), and 33 (27, 44) mmHg, respectively. The Pearson correlation coefficient and the 95% limits of agreement between GAT readings and Tono-Pen readings at the central cornea were 0.9 (P < .001) and -4.9 to 8.74 mmHg, respectively. The correlation coefficient between GAT readings and Tono-Pen readings at the limbus and GAT readings and Tono-Pen readings at the sclera was 0.46 (P < .001) and 0.23 (P = .01), respectively. The 95% limits of agreement between these pairs of readings were -20.55 to 13.66 and -44.02 to 13.37 mmHg, respectively. CONCLUSIONS: This study showed limited ability of Tono-Pen readings obtained at the limbus and sclera to predict the central corneal GAT IOP readings in eyes with normal corneas at various IOP ranges.

Estimation of Goldmann applanation tonometer intraocular pressure (IOP) from scleral Schiotz IOP values in eyes with type-1 keratoprostheses.

PURPOSE: To validate estimation of Goldmann applanation tonometer (GAT) intraocular pressure (IOP) from scleral Schiotz IOP measurements using a regression model in normal eyes and eyes with type-1 keratoprostheses. METHODS: In this prospective cross-sectional study, cohort-1 had 253 normal anterior segment eyes, and cohort-2 had 100 eyes with type-1 keratoprostheses. Scleral Schiotz IOP measurements were used (in a non-linear model) to predict GAT IOP values for these eyes. Accuracy of predicted GAT IOP values was assessed using actual GAT IOP values for normal eyes, while for type-1 keratoprosthetic eyes, finger tension (FT) IOP assessments by an experienced glaucoma specialist were used. Primary outcome was agreement between FT IOP (assessed by an experienced glaucoma specialist) and predicted GAT IOP-derived clusters. RESULTS: The actual values of GAT IOP measurements in normal eyes (n=253; mean age ±SD, 51.35±15.56 years) ranged between 6 mm Hg and 62 mm Hg (mean=22±10.05 mm Hg). Estimated and actual GAT IOP values for normal eyes were very similar (mean difference=0.05 mm Hg with limits of agreement: -5.39 to 5.5 by Bland-Altman plot). Of the 100 eyes with type-1 keratoprostheses, 68 were classified as having digitally normal IOP, 28 as borderline and 4 as high. The agreement between classification by FT assessment and model-predicted GAT IOP values was substantial (Kappa=0.81, 95% CI 0.69 to 0.93). The accuracy of the model in assessing IOP was found to be 91% (95% CI 0.84 to 0.96). CONCLUSION: Scleral Schiotz IOP values along with our predictive model can be an alternative objective method to FT IOP in assessing IOP in eyes with type-1 keratoprostheses.

Adaptive optics scanning laser ophthalmoscopy may support early diagnosis of glaucoma.

Purpose: To compare image characteristics of retinal nerve fiber layer (RNFL) between glaucoma patients and healthy controls using adaptive optics scanning laser ophthalmoscopy (AOSLO). Methods: This was a cross-sectional pilot study with two groups: a glaucoma group with patients with moderate or severe glaucoma as per the Hodapp-Parrish-Anderson classification system and a control group with healthy individuals. The optic nerve damage in moderate glaucoma was predominantly located in only one hemisphere; the other hemisphere was un- or minimally affected on optical coherence tomography and automated perimetry and is referred to as early glaucoma. The structure of RNFL bundles and gain (%) in RNFL images with mean pixel values between 15 and 35 were analyzed. Imaging was performed one degree away from the optic disc margin at two and four cardinal clock positions in the glaucoma and control groups, respectively. The field of view was 1.3° at 2.3 µ resolution. We studied one eye per participant. Results: There were 11 glaucoma patients and 7 healthy controls. Imaging was successful at 88% of the locations in controls and early glaucoma; the reflectivity differed significantly (0.51 and 0.56, respectively, P < 0.001) but not the structure of RNFL bundles (Cohen's Kappa 0.11) between them. In patients with moderate and severe glaucoma, imaging was successful only at 46% of the locations; RNFL bundles were not discernible, and RNFL reflectivity did not differ from those with early glaucoma (P < 0.11). Conclusion: The recorded gain (%) of RNFL images obtained using AOSLO could be an objective indicator of early glaucoma.

Steroid-induced glaucoma and blindness in vernal keratoconjunctivitis.

PURPOSE: To report the clinical features, treatment outcomes and blindness associated with steroid-induced glaucoma in vernal keratoconjunctivitis (VKC). MATERIALS AND METHODS: Records of patients with VKC, who visited our tertiary centre from 1992 and 2009, were reviewed and those with steroid-induced glaucoma were included in the study. Glaucoma was diagnosed based on intraocular pressure (IOP) ≥22 mm Hg on two consecutive visits (ocular hypertension) and/or glaucomatous optic disc damage. Blindness was defined as best corrected visual acuity of ≤20/400 or visual field <10°. RESULTS: Of the 4062 VKC subjects, 91 (157 eyes) had steroid-induced glaucoma (SIG), showing a prevalence of 2.24%. Of these 87% were men. The median (IQR) age at onset of VKC was 12 years (7-17). At presentation, the median duration of VKC was 48 months (24-72) and the median duration of steroid usage was 24 months (12-36). The median cup-to-disc ratio (CDR) was 0.9 (0.7-0.9) and median mean deviation was -21.9 dB (-30.0 to -10.2). IOP was medically controlled in 66% eyes (104/157) and 34% eyes (53/157) needed glaucoma surgery. High presenting IOP (OR: 1.04; p=0.05) and increased duration of steroid usage (OR: 1.07; p=0.02) were significantly associated with need for glaucoma surgery. At presentation, 29/91 subjects (31.8%) were bilaterally blind due to SIG. Higher CDR at presentation was significantly associated with blindness in this cohort (p=0.02). CONCLUSION: In this cohort of VKC with SIG, the disease predominantly affected adolescent males. Glaucoma was severe with one-third needing surgery and one-third blind due to SIG.

LVPEI Glaucoma Epidemiology and Molecular Genetic Study: teleophthalmology screening for angle-closure disease in an underserved region.

OBJECTIVES: To assess the ability of teleophthalmoscopic grading of peripheral anterior chamber depth (PACD) using the van Herick (vH) technique in detecting gonioscopically occludable angle; and to determine whether combining results from vH grading and ocular biometry can improve the accuracy to diagnose gonioscopically occludable angle METHODS: This cross-sectional study was an offshoot of a rural population-based study, Glaucoma Epidemiology and Molecular Genetic Study (GLEAMS). A masked urban ophthalmologist graded digital slit lamp photographs of PACD by vH technique. Sussman four-mirror lens was used to perform dark room indentation gonioscopy. Cutoff values of the tests were, vH technique: grade ≤ 2, central anterior chamber depth (ACD), as well as axial length: ≤ 25th percentile and lens thickness ≥ 75th percentile value of the study population. RESULTS: We studied 1965 eyes of 1029 adult participants. The vH grade was ≤2 in 188 (9.5%) eyes. The angle was occludable by gonioscopy in 101 (5.1%) eyes. The performance of the vH test to rule out gonioscopically occludable angle was good [negative predictive value (NPV): 97.3%], despite low sensitivity (52.5%), while its efficacy to rule in the condition was low [positive predictive value (PPV): 28.2%] despite high specificity (92.8%). However, test combination strategy increased the PPV nearly twofold (53.8%). The calculated PPV at 10% prevalence of gonioscopically occludable angle was even higher (70.5%). CONCLUSIONS: Van Herick technique can be incorporated into a teleophthalmology program by means of slit lamp photographs of PACD. Combined vH grading and ocular biometry improved the predictability of a gonioscopically occludable angle.

Toward Better Health Outcomes in Rural and Under-served Areas: L. V. Prasad Eye Institute's Diagonal Model of Glaucoma Care.

Purpose: L. V. Prasad Eye Institute has adopted horizontal approach of eye care delivery for the past 22 years at one of its rural secondary centers. The recent implementation of a diagonal model for enhancing glaucoma care at this center and its outcomes are reported.Methods: This was a retrospective case-control study. We included newly and consecutively diagnosed adult glaucoma patients. A comprehensive ophthalmologist provided glaucoma care. During the study period, an experienced glaucoma specialist supported the care for 2 days every month in a structured format that consisted of triaging glaucoma patients for defined protocols of therapy along with hands-on and remote online guidance to the comprehensive ophthalmologist. The data from the worst or single eye were analyzed.Results: We have included 231 patients (151 study and 80 historical controls). Sixty (75%) control patients were managed at the study center and 20 (25%) were referred. The comprehensive ophthalmologist managed 70 (48.2%) study patients and co-managed 75 (51.7%) with the glaucoma specialist. The latter changed the diagnosis in 15 eyes and altered the treatment plan in 44 eyes. Six were excluded. Successful outcome was achieved in 52 (65%) eyes in the control group and 120 (84.5%) eyes in the study group (P < .01). Additionally, study group did better in terms of case detection rate, compliance to treatment and saving on expenses for patients.Conclusion: The new model has shown better clinical outcomes of glaucoma care in an under-served geographic area. The model has the potential for wider applicability.

Combination of Simple Diagnostic Tests to Detect Primary Angle Closure Disease in a Resource-constrained Region.

Purpose: To report on diagnostic accuracy of van Herick (vH) technique performed by a vision technician (VT) as well as on efficacy of a combination of vH technique and central anterior chamber depth (ACD) in detection of primary angle closure disease.Methods: Data was obtained from two cohorts; rural clinic setting (n = 111), and rural population-based research setting (n = 888). Van Herick grading was performed by a VT in first cohort and a glaucoma specialist in second cohort. A reference standard four-mirror gonioscopy was performed by a glaucoma specialist in both cohorts. We did preferential sampling. Cut-off levels for vH technique and central ACD were grade 2 and 25th percentile value, respectively. Data from one eye per participant was analyzed.Results: Three hundred and forty (34%) eyes were gonioscopically occludable. Area under receiver operating characteristic curve (95% confidence interval) for vH test was 0.83 (0.76, 0.9) and 0.81 (0.78, 0.84) in first and second cohorts, respectively. Simultaneous testing achieved sensitivity of 87.8% while sequential testing achieved specificity of 99.3%. Negative predictive value* of simultaneous testing was 98.3% compared to 96.6% of vH technique while positive predictive value* of sequential testing was 86% compared to 49.3% of vH technique. (*at 10% prevalence of gonioscopically occludable angle)Conclusions: Diagnostic accuracy of vH grading was similar when performed by a VT and a glaucoma specialist. While test combination was effective to rule in, vH technique may suffice to rule out the disease. Implications of these findings for resource-constrained regions are discussed.

Comparison of Visual Field Progression Rates Among the High Tension Glaucoma, Primary Angle Closure Glaucoma, and Normal Tension Glaucoma.

Purpose: To compare the visual field (VF) progression among high tension glaucoma (HTG), primary angle closure glaucoma (PACG), and normal tension glaucoma (NTG) subjects in routine clinical care. Methods: All patients had ≥5 VF tests using HFA, 24-2, SITA-standard strategy. We compared the progression between glaucoma subtypes after matching the VFs for baseline severity (mean deviation [MD]) and the age at presentation. Global VF progression was evaluated by linear regression analysis (LRA) of MD. For local VF progression, scotoma expansion (SE) defined as appearance of new scotoma and scotoma deepening (SD) defined by pointwise LRA were calculated. SE and SD were analyzed in three VF zones: superior arcuate (SA), inferior arcuate (IA), and central (C). Results: A total of 310 HTG, 304 PACG, and 165 NTG eyes were included. When VFs were matched by baseline MD, a greater number (n = 20/76) of eyes with HTG showed significant progression compared to PACG (n = 9/76; P = 0.04). The number of progressing eyes were not significantly different between HTG and NTG (n = 11/76; P = 0.10) and between NTG and PACG (P = 0.65). When the baseline VFs were matched by age, the number of eyes showing significant progression were similar in all the subtypes. SA zone in HTG and NTG showed greater SE and SD compared to other zones (P < 0.05), whereas IA zone in PACG showed greater SE and SD compared to other zones (P < 0.05). Conclusions: In our cohort of treated primary glaucoma with matched baseline severity, a greater proportion of HTG eyes progressed faster compared to PACG. SA zone in HTG and NTG and IA zone in PACG showed greater VF progression.

Diagnostic Accuracy of Van Herick Technique to Detect Pre-Disease States of Primary Angle Closure Glaucoma in a Resource Constraint Region.

OBJECTIVES: To critically evaluate diagnostic accuracy of the van Herick (vH) technique in detection of gonioscopically occludable angle in a rural population and to explore ways to improve accuracy of the technique Methods: The study cohort was formed by two-stage cluster random sampling. Peripheral anterior chamber depth grading was performed, using both traditional and modified (photographic comparison) vH techniques, under dark adapted and standard lighting conditions by a comprehensive ophthalmologist masked to the clinical features. The cut-off criterion for vH test was 25% of peripheral corneal thickness. The reference standard was dark room 4-mirror indentation gonioscopy performed by an experienced glaucoma specialist. This study adhered to the STARD guidelines for reporting diagnostic accuracy studies. RESULTS: We studied 111 eyes of 111 participants. The median age was 62 years. The angle was occludable by gonioscopy in 69 (62%) eyes; 58 eyes were primary angle closure suspects and 11 were primary angle closure patients. The likelihood ratio (95% confidence interval (CI)) of the positive (LR+) and negative (LR‒) result by the traditional vH technique was 5.17 (2.43, 11) and 0.30 (0.20, 0.46), respectively. The LR+ by reducing and LR‒ by elevating the cut-off grade of the traditional vH technique were 9.4 (2.3, 37.4) and 0.08 (0.02, 0.31), respectively. The area under receiver operating characteristic curve did not differ significantly by photographic comparison or lighting condition (p = 0.13). CONCLUSIONS: vH grading can be considered as a triage test before gonioscopy. The value of the vH technique to the diagnostic strategy is discussed.

Prevalence of Primary Glaucoma as Diagnosed by Study Optometrists of L. V. Prasad eye Institute - Glaucoma Epidemiology and Molecular Genetics Study.

PURPOSE: To report the prevalence of primary glaucoma as identified by study optometrists of the L. V. Prasad Eye Institute - Glaucoma Epidemiology and Molecular Genetics Study (LVPEI-GLEAMS). METHODS: Two study optometrists and a total number of 3833 individuals participated in the LVPEI-GLEAMS. All subjects underwent a complete medical history and comprehensive eye examination including slit lamp photography, imaging of anterior and posterior segment, frequency doubling technology and standard automated perimetry including gonioscopy with a Sussman 4 mirror goniolens, post dilated evaluation of the optic disc and fundus was done with a 90 D lens by the study optometrist. A diagnosis of primary open angle glaucoma (POAG), primary angle closure suspect (PACS), primary angle closure (PAC), primary angle closure glaucoma (PACG), normal tension glaucoma (NTG), glaucoma/disc suspect or no glaucoma was made based on the clinical examination. RESULTS: Estimated prevalence of OAG (POAG and NTG) was 1.07% (0.74-1.39), PACS 2.03% (1.58-2.48), PAC 1.77% (1.35-2.19), PACG 0.21% (0.06-0.35) as identified by the study optometrists on site. CONCLUSIONS: Prevalence of all the categories of primary glaucoma, as reported by the study optometrists of LVPEI-GLEAMS was comparable to previous findings of other regions in South India.

Outcomes of lensectomy and risk factors for failure in spherophakic eyes with secondary glaucoma.

PURPOSE: To report the outcomes of lensectomy in spherophakic eyes with subluxated or dislocated crystalline lenses and secondary glaucoma. METHODS: Lensectomy was performed in 52 eyes, 36 eyes with lens subluxation and 16 eyes with lens dislocation with secondary glaucoma from 1991 to 2016. Glaucoma was diagnosed based on intraocular pressure (IOP) ≥22 mm Hg and/or glaucomatous optic disc damage. Complete success was defined as IOP ≥5 and ≤21 mm Hg without antiglaucoma medications (AGMs) or surgery, and eyes needing oral AGM or surgical intervention for IOP control or those with complication causing loss of light perception were considered failure. RESULTS: Median (IQR) age at lensectomy was 12 (6-18) years, and median spherical equivalent was -14.5D (-23.7to -13). Median follow-up was 30.6 (5.4-103.4) months. Median logMAR (logarithm of minimal angle of resolution) visual acuity improved from 0.95 (0.6-1.8) to 0.4 (0.2-1.3) after lensectomy (p=0.01). Median IOP decreased from 22 mm Hg (17-31) to 14 mm Hg (11-19) at final follow-up (p=0.01). Median number of AGM decreased from 2 (2-3) to 1 (0-2) at final follow-up (p<0.0001), and glaucoma surgery was needed in four eyes (7.7% eyes). Complete success probability was 69% at 1 year and 51% at 5 years. Younger age (<6 years), higher presenting IOP (>32 mm Hg) and larger cup to disc ratio at presentation were found to be significant risk factors for failure. CONCLUSION: Lensectomy was effective in controlling IOP in close to half of all eyes with spherophakia and secondary glaucoma, 40% eyes needed AGM and only 7.7% eyes needed glaucoma surgery for IOP control. In this cohort, younger age, higher IOP and larger cup to disc ratio at presentation were risk factors for poor glaucoma control after lensectomy.

Is Ahmed Glaucoma Valve Consistent in Performance?

PURPOSE: To investigate the mechanism of action and consistency in flow characteristics of the Ahmed glaucoma valve (AGV) under simulated physiological conditions in-vitro and to evaluate whether resistance during priming has any effect on performance of the device. METHODS: Each newly opened AGV device was connected to a digital manometer and was primed with normal saline. The device was then placed in a saline bath and connected to an open manometer, a digital manometer, and an infusion pump. Saline was infused at a rate of 3 µL/min for 24 hours. Digital manometer readings were recorded at 4 Hz. RESULTS: Data obtained from 9 devices are presented as medians (ranges). The priming pressure was 1130 (835, 1625) mm Hg. Pressure versus time curves showed two distinct phases; transient and steady phases. The transient phase peak pressure was 24 (13, 45) mm Hg. In the steady phase, opening and closing pressures were 13 (10, 17) and 7 (4, 9) mm Hg, respectively; the valve leaflets briefly opened every 73.9 (51, 76.6) minutes and the fluctuation of pressure (difference between opening and closing pressures) was 6 (3, 9) mm Hg. The Spearman correlation coefficient between priming and opening and priming and closing pressure was ρ = -0.13 (P = 0.72) and ρ = -0.36 (P = 0.33), respectively. CONCLUSIONS: The device showed functionality like a valve. The resistance during priming did not affect opening and closing pressures of the AGV. This study showed variable in vitro performance of the AGV. TRANSLATIONAL RELEVANCE: These laboratory findings might, at least partly, explain the variability in the clinical outcome of the device.

Outcomes of Bleb Repair for Delayed Bleb Leaks and Sweating Blebs.

PURPOSE: To report the outcomes of bleb repair for delayed onset leaking blebs and sweating blebs following glaucoma filtering surgery. MATERIALS AND METHODS: Medical records of 76 eyes of 76 subjects that underwent bleb repair for either leaking bleb or sweating bleb between 1990 and 2015 were reviewed. Complete success was resolution of bleb leak and or hypotony with intraocular pressure ≥5 and ≤21 mm Hg with no antiglaucoma medication. RESULTS: There were 45 eyes with leaking bleb and 31 eyes with sweating bleb that underwent bleb repair by either conjunctival autograft or conjunctival advancement (P=0.11). Before bleb repair, complications like blebitis and hypotony maculopathy were significantly higher in sweating bleb group (13/31) compared with bleb leak group (5/45) (P=0.002). Median follow-up after bleb repair was >2 years in both groups (P=0.69). After repair, eyes in leaking bleb group had higher immediate (P=0.01) and long-term intraocular pressure elevation (P=0.06) compared with sweating bleb group. Complete success probability in sweating bleb group was significantly better (88%, 78%, and 71%) compared with leaking bleb group (54%, 45%, and 40%) at 1, 3, and 6 years, respectively (P=0.01). One eye in each group had blebitis, 2 eyes in leaking bleb group and 1 eye in sweating bleb group needed repeat glaucoma intervention. CONCLUSIONS: Higher complication rate before bleb repair in eyes with sweating bleb warrants early bleb repair. Bleb repair helped retain bleb function in majority of the eyes with sweating blebs, strengthening our recommendation.

A Simplified (Screening) Approach to Check the Calibration Status of the Goldmann Applanation Tonometer.

BACKGROUND: To investigate whether a lower-end calibration error check alone can identify a Goldmann applanation tonometer (GAT) with acceptable calibration error as per Asia-Pacific Glaucoma Society (APGS) and World Glaucoma Association (WGA) guidelines. METHODS: This was a multicentric prospective study in a tertiary eye-care institutional setting. Seventy-six slit-lamp-mounted Haag-Streit GATs (Model AT 900 C/M) were included in the study. All GATs were checked for calibration error at 0, 20, and 60 mm Hg testing levels as recommended by the manufacturer. The ability of 2 screening criteria (calibration error within ±1 or ±2 mm Hg, respectively, at the 0 mm Hg testing level without using the calibration error check weight bar) to identify a tonometer within acceptable calibration limits defined by APGS (calibration error within ±2, ±3, and ±4 mm Hg at 0, 20, and 60 mm Hg testing levels, respectively) and WGA (calibration error within ±1 mm Hg at all testing levels) was determined. MAIN OUTCOME MEASURE: The negative likelihood ratio of the screening criteria RESULTS:: Five (6.6%) and 42 (55%) GATs were outside of the APGS and the WGA calibration limits, respectively. Negative likelihood ratios of the first and the second screening criteria at the APGS definition of calibration error tolerance were 0.11 and 0.25, respectively, and at that of the WGA definition of calibration error tolerance were 0.38 and 0.90, respectively. CONCLUSIONS: The screening criteria of calibration error within ±1 mm Hg at the 0 mm Hg testing level seem to be clinically useful to detect GAT with an acceptable calibration error as per the APGS guideline.

Optic nerve head parameters of high-definition optical coherence tomography and Heidelberg retina tomogram in perimetric and preperimetric glaucoma.

BACKGROUND: Heidelberg retina tomogram (HRT) and optical coherence tomography (OCT) are two widely used imaging modalities to evaluate the optic nerve head (ONH) in glaucoma. PURPOSE: To compare the ONH parameters of HRT3 and high-definition OCT (HD-OCT) and evaluate their diagnostic abilities in perimetric and preperimetric glaucoma. DESIGN: Cross-sectional analysis. METHODS: 35 control eyes (24 subjects), 21 preperimetric glaucoma eyes (15 patients), and 64 perimetric glaucoma eyes (44 patients) from the Longitudinal Glaucoma Evaluation Study underwent HRT3 and HD-OCT examinations. STATISTICAL ANALYSIS: Agreement between the ONH parameters of HRT and HD-OCT were assessed using Bland-Altman plots. Diagnostic abilities of ONH parameters were evaluated using area under the receiver operating characteristic curves (AUCs), sensitivity at fixed specificity, and likelihood ratios (LR). RESULTS: Optic disc area, vertical cup to disc ratio, and cup volume with HD-OCT were larger than with HRT, while the rim area was smaller with HD-OCT (P < 0.001 for all comparisons). AUCs of all HD-OCT ONH parameters (0.90-0.97 in perimetric and 0.62-0.71 in preperimetric glaucoma) were comparable (P > 0.10) to the corresponding HRT ONH parameters (0.81-0.95 in perimetric and 0.55-0.72 in preperimetric glaucoma). LRs associated with diagnostic categorization of ONH parameters of both HD-OCT and HRT were associated with larger effects on posttest probability of perimetric compared to preperimetric glaucoma. CONCLUSIONS: ONH measurements of HD-OCT and HRT3 cannot be used interchangeably. Though the diagnostic abilities of ONH parameters of HD-OCT and HRT in glaucoma were comparable, the same were significantly lower in preperimetric compared to perimetric glaucoma.

An ultrasound biomicroscopic study of the anterior segment in Indian eyes with primary angle-closure glaucoma.

PURPOSE: To evaluate the presence of plateau iris in eyes with primary angle-closure glaucoma (PACG) after laser peripheral iridotomy by gonioscopy and ultrasound biomicroscopy and to evaluate the pathogenesis of this condition by comparing the UBM parameters of these eyes with those in normal subjects. PATIENTS AND METHODS: This prospective study was carried out in the Glaucoma clinic of a tertiary eye care center. A detailed clinical examination including applanation tonometry, indentation gonioscopy with a Sussman four-mirror gonioscope, and ultrasound biomicroscopic examination in one randomly selected eye of 55 patients (55 eyes) with PACG who had undergone laser peripheral iridotomy and 22 normal subjects (22 eyes). RESULTS: Among the PACG eyes, 40% (22/55) had an open angle (angle opening distance > 130 microns) and 60% (33/55) eyes had a narrow angle (angle opening distance

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.

Comparison of outcomes of trabeculectomy with mitomycin C vs. ologen implant in primary glaucoma.

PURPOSE: To compare the safety and efficacy of trabeculectomy with Ologen implant vs. trabeculectomy with Mitomycin C (MMC). MATERIALS AND METHODS: In a prospective, randomized, pilot study, 39 eyes of 33 subjects with medically uncontrolled primary glaucoma, aged 18 years or above underwent trabeculectomy either with MMC (20 eyes) or with Ologen implant (19 eyes). The primary outcome measure was cumulative success probability, defined as complete if the intraocular pressure (IOP) was > 5 and ≤ 21 mm Hg without anti-glaucoma medications or additional surgery and qualified if an IOP was > 5 and ≤ 21 mm Hg with or without anti-glaucoma medications. RESULTS: Mean (± standard deviation) follow-up in Ologen group was 19.1 ± 8.1 months, and in MMC group was 18.0 ± 8.4 months. Mean IOP reduction at 6 months was significantly lower (P = 0.01) in the MMC group (11.9 ± 2.9 mm Hg) as compared to Ologen group (14.6 ± 2.7 mm Hg). However, at 12 months (P = 0.81) and 24 months (P = 0.32), the mean IOP was similar between the 2 groups. Complete success probability at the end of 6 months in Ologen group was 100% (95% confidence interval: 59.1 - 99.0) was similar (P = 0.53) to that in MMC group (93.8%, 95% CI: 63.2 - 99.1). The incidences of early post-operative complications were similar in the 2 groups, except hyphema, which was significantly more in Ologen group (P = 0.02). CONCLUSION: In this pilot study, the success of trabeculectomy and complications were similar in both Ologen and MMC groups at the end of 6 months.

LV Prasad Eye Institute Glaucoma Epidemiology and Molecular Genetic Study (LVPEI- GLEAMS). Report 1: study design and research methodology.

PURPOSE: In the developing world, more than 90% of glaucoma is undetected due to the lack of appropriate screening methods. The LV Prasad Eye Institute Glaucoma Epidemiology and Molecular Genetic Study (LVPEI-GLEAMS) is a population-based study which aims to estimate the prevalence of, along with clinical, systemic and genetic risk factors for glaucoma in a rural population sampled from the state of Andhra Pradesh, India. The study aims to develop community screening strategies to diagnose glaucoma. This article describes the methodology adopted in LVPEI-GLEAMS. METHODS: A sample of 3833 participants aged 40 years and older has been estimated to be enrolled using a compact segment sampling method with probability proportionate to size. Each participant will undergo a complete medical history and comprehensive eye examination including slit lamp photography, imaging of anterior and posterior segment, frequency doubling technology and standard automated perimetry. Additionally, glycosylated hemoglobin will be measured and a genetic profile based on candidate gene analysis will be undertaken. Clinical, biochemical and genetic data will be stored in a computerized database and analyzed. The novelty of this study lies in the fact that it is conducted at a vision center (primary eye care center serving a population of 50,000) by a vision technician (high school educated rural youth trained in basic ophthalmic techniques for a year). CONCLUSION: Information from the diagnostic techniques of the study will be used to develop effective community-level screening strategies, and insights from risk factors associated with glaucoma will help develop appropriate detection and management strategies.