Inter-instrument agreement and influence of central corneal thickness on measurements with Goldmann, pneumotonometer and noncontact tonometer in glaucomatous eyes.

PURPOSE: This study was conducted to compare the intraocular pressure (IOP) measurements by the Goldman applanation tonometer (GAT), non contact tonometer (NCT) and the ocular blood flow (OBF) pneumotonometer in different IOP ranges in glaucomatous eyes. The effect of central corneal thickness (CCT) on IOP measurement in chronic glaucomatous eyes using the three different tonometers was also evaluated. MATERIALS AND METHODS: IOP measurements of 130 eyes of primary glaucoma patients were performed using GAT by an ophthalmologist while NCT and OBF-pneumotonometer measurements were performed by an experienced optometrist. The IOP values were compared amongst the three instruments in the three different IOP ranges (0-18 mmHg, > 18 to 25 mmHg, > 25 mmHg). CCT was also measured in all patients. RESULTS: The mean of paired difference between GAT and NCT was 0.9 +/- 3.1 mmHg while that between GAT and OBF-pneumotonometer was 0.3 +/- 3.4 mmHg. The OBF-pneumotonometer and NCT were more affected by corneal thickness (0.41 mmHg and 0.4 mmHg / 10 micro corneal thickness respectively) while GAT was the least affected by corneal thickness (0.3 mmHg / 10 micro corneal thickness) though the difference was not statistically significant ( P =0.42). CONCLUSION: With appropriate correction for corneal thickness the NCT and OBF-pneumotonometer can be used as reliably as GAT in following up glaucomatous patients.

Quantification of the retinal nerve fibre layer thickness in normal Indian eyes with optical coherence tomography.

PURPOSE: To quantitatively assess the normative values for peripapillary retinal nerve fibre layer (RNFL) thickness with Optical Coherence Tomography (OCT 3) in Indian subjects. METHODS: The peripapillary retinal nerve fibre layer of 146 normal subjects was imaged on OCT 3 in this cross-sectional study. Thickness of the RNFL around the disc was determined with three 3.4 mm diameter circle OCT scan. The RNFL thickness was measured in four quadrants; superior, nasal, inferior and temporal. The data was analysed using SAS commercial statistical software. Influence of age and gender was evaluated on various measured parameters using unpaired t test, one-way analysis variance (ANOVA) and Pearson's correlation coefficient. RESULTS: One hundred and forty six eyes of 146 patients, 84 males and 62 females were studied. The average RNFL thickness in the sample population under study was 104.27 +/- 8.51 (95% CI 87.25-121). The RNFL was thickest in the inferior quadrant, followed by the superior quadrant, and progressively less in nasal and temporal quadrant. The difference between inferior and superior quadrants was not statistically significant. Age had a significant negative correlation with average RNFL thickness (r = -0.321, P = 0.000) and with average superior (r = -0.233, P = 0.005) and average inferior RNFL thickness (r = -0.234, P = 0.004). There was no effect of gender on various RNFL thickness parameters. CONCLUSIONS: RNFL thickness is significantly correlated with age, but not with gender. This normative database of RNFL thickness with OCT in Indian eyes is similar to previously reported values in normal Asian eyes.

Macular thickness evaluation using the optical coherence tomography in normal Indian eyes.

PURPOSE: To determine the normative values for macular thickness and volume by Optical Coherence Tomography (OCT 3) in healthy Indian subjects. METHODS: The macula of 170 consecutive, randomly selected normal subjects was imaged on OCT 3 in this cross-sectional study. OCT parameters of macular thickness were analysed with baseline variables including age, gender, axial length and refractive error. RESULTS: The average foveal thickness in the population under study was 149.16 +/- 21.15 micro. Macular thickness and volume parameters of OCT correlated significantly (Pearson's Correlation coefficient) with age (r=0.23, P<0.01), but not with gender, axial length and refraction. CONCLUSIONS: The macular thickness and volume parameters have a significant correlation with age. This normative database of macular thickness by OCT in Indian eyes may be a useful guideline for management and further research in diseases of the macula and glaucoma.

Timolol maleate 0.5% versus timolol maleate in gel forming solution 0.5% (Timolol GFS) in open angle glaucoma in India. Preliminary safety and efficacy study.

PURPOSE: To compare the efficacy and safety profile of Timolol maleate 0.5% versus Timolol gel forming solution (GFS) 0.5% in open angle glaucoma in Indian eyes. METHODS: In a prospective crossover study 52 patients of open angle glaucoma, well controlled intraocular pressure (IOP) on 0.5% timolol maleate solution were switched over to timolol GFS once a day, after a washout period of one month. A diurnal IOP measurement was done after 6 weeks and compared with patients on timolol maleate 0.5% twice a day. In addition, side effects reported or observed were compared. RESULTS: Statistically significant difference was not observed in ocular hypotensive effect of the two treatment. The side-effects in both the treatment groups were similar except for higher incidence of blurring of vision in patients on timolol GFS. The compliance was better with timolol GFS, but was not statistically significant. CONCLUSION: The results of this study suggest that the more convenient 0.5% timolol in gel forming solution can be offered as an equally efficacious and well-tolerated alternative to twice daily 0.5% timolol solution in open angle glaucoma.