Blebs, Barriers, and Bagpipes: Why is It so Hard?
[Year:2016] [Month:September-December] [Volume:10] [Number:3] [Pages:6] [Pages No:79 - 84]
Keywords: Capsule, Glaucoma, Glaucoma device, Outflow, Porosity, Surgery
DOI: 10.5005/jp-journals-10008-1206 | Open Access | How to cite |
Doug Johnson was a clinician-scientist who made great contributions to the understanding of outflow from the eye. This lecture is in honour of Doug and explores the author's understanding of outflow in the surgical context.
Macular Thickness Assessment in Patients with Glaucoma and Its Correlation with Visual Fields
[Year:2016] [Month:September-December] [Volume:10] [Number:3] [Pages:6] [Pages No:85 - 90]
Keywords: Glaucoma, Macula, Optical coherence tomography, RNFL, Visual field
DOI: 10.5005/jp-journals-10008-1207 | Open Access | How to cite |
Aim: To determine the relationship between macular thickness (MT) and visual field (VF) parameters, as well as with changes in the retinal nerve fiber layer (RNFL) thickness in patients with glaucoma and ocular hypertension (OH). Materials and methods: Cross-sectional statistical analysis of spectral domain optical coherence tomography (SD-OCT) compared with several VF parameters (mean defect - MD and loss variance - LV), in a nonrandom sample of 70 eyes from patients with glaucoma or OH. Statistical analysis was performed using Statistical Package for Social Sciences®. The correlation coefficient used was determined by Spearman correlation and the value of p < 0.05 was considered statistically significant. Results: A significant correlation was seen between VF parameters and decrease in MT (MD: r = -0.363, p = 0.002; LV: r=-0.378, p = 0.001). The results were more significant when we compared the LV in the group with average MT 270 to 300 μm (r = -0.413, p = 0.015). Asymmetry between the superior macula and inferior macula correlated with LV (r = 0.432, p = 0.019) in the group with MT < 270 μm. There was also a significant correlation between thinning of superior-temporal and inferior-temporal RNFL and the decrease of the superior and inferior MT respectively (p < 0.001). Conclusion: Spectral domain optical coherence tomography measurements of retinal thickness in the macula correlate with VF parameters and RNFL parameters in glaucoma patients. This relationship was first demonstrated with static computerized perimetry made with Octopus 101®. These results can be a valuable aid for evaluating and monitoring of glaucoma patients, establishing a correlation between structure and function. Measurements of retinal thickness in the macula may be an additional instrument for early detection of structural changes and its correlation with functional defects.
Porosity of Bleb Capsule declines rapidly with Fluid Challenge
[Year:2016] [Month:September-December] [Volume:10] [Number:3] [Pages:6] [Pages No:91 - 96]
Keywords: 3D Printed implant, Aqueous outflow, Capsular porosity, Filtering surgery, Glaucoma drainage device, Glaucoma, Hydraulic conductivity, Rabbit model, Rapid failure
DOI: 10.5005/jp-journals-10008-1208 | Open Access | How to cite |
Introduction: The porosity of the fibrous capsule around a glaucoma drainage device (GDD) may be the most important functional attribute. The factors that determine capsular porosity are not well understood. Failed GDD surgeries are usually associated with thick impervious capsules and components of aqueous have been implicated in this process. Purpose: In this study, we interrogated the effect of passage of nonaqueous fluid on capsular porosity in mature (but aqueous naive) blebs in a previously reported GDD model (the “Center for Eye Research Australia Implant”). Materials and methods: The study was performed at two centers using 17 New Zealand White (NZW) rabbits. An experimental GDD was implanted into the subconjunctival space but without connection to the anterior chamber. After 28 days, balanced salt solution (BSS) was passed through the implant for 30 to 40 minutes at 12 mm Hg. Capsular porosity was measured as flow (ul_/min) at a constant pressure. Porosity of the capsule was retested at 3 and 6 days. Results: There was a marked reduction in capsular porosity within 3 days of exposure to BSS (fluid challenge). Even though the baseline porosity was significantly different in the two groups (3.00 ± 0.5 ul_/min and 29.67 ± 12.12 ul_/min, p < 0.001), the effect of passage of BSS was similar. Capsular porosity fell by approximately 80% in both groups from baseline after single BSS challenge. Capsular thickness was significantly less in Advanced Eye Center (AEC) rabbits at baseline. There was no change in the capsular thickness before and after single fluid challenge. Conclusion: Passage of BSS at physiological pressures for under 40 minutes caused marked reduction in the porosity of the fibrous capsule within 3 days. This was not associated with any significant thickening of the fibrous capsule within this time frame.
Intraocular Pressure Control after Implantation of an Ahmed Glaucoma Valve in Eyes with a Failed Trabeculectomy
[Year:2016] [Month:September-December] [Volume:10] [Number:3] [Pages:7] [Pages No:97 - 103]
Keywords: Ahmed glaucoma valve, Glaucoma surgery, Intraocular pressure, Retrospective study
DOI: 10.5005/jp-journals-10008-1209 | Open Access | How to cite |
Aim: To evaluate the results of Ahmed glaucoma valve (AGV) in eyes with a failed trabeculectomy. Materials and methods: This retrospective study evaluated 61 eyes with a failed trabeculectomy that underwent implantation of an AGV due to uncontrolled intraocular pressure (IOP) on maximal medical therapy. Success was defined as IOP < 21 mm Hg (criterion 1) or 20% reduction in IOP (criterion 2) with or without antiglaucoma medications. Persistent hypotony, loss of light perception, and reoperation for IOP control were defined as failure. Results: Mean preoperative IOP and mean lOPs at 6, 12, and 24 months were 21.93 ± 6.32 mm Hg (n = 61), 14.15 ± 4.33 mm Hg (n = 59), 13.21 ± 4.44 mm Hg (n = 56), and 13.60 ± 3.27 mm Hg (n = 25) respectively. Mean number of antiglaucoma medications preoperatively and at 6, 12, and 24 months was 3.95 ± 0.85, 2.19 ± 1.38, 2.48 ± 1.44, and 2.40 ± 1.32 respectively. The reductions in the number of medications and IOP measurements were statistically significant at all time intervals (p < 0.001, Wilcoxon signed rank test). According to criterion 1, the Kaplan-Meier survival curve disclosed success rates of 75% at 12 and 24 months. According to criterion 2, the success rates were 57% at 12 months and 55% at 24 months. The most frequent complications were hypertensive phase (18%) and shallow anterior chamber (16.4%). Conclusion: The AGV may effectively reduce IOP in eyes that had a failed trabeculectomy. Clinical significance: The AGV is an alternative in eyes with a failed trabeculectomy.
Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma
[Year:2016] [Month:September-December] [Volume:10] [Number:3] [Pages:9] [Pages No:104 - 112]
Keywords: Color Doppler imaging, Glaucoma, Ocular perfusion pressure, Retrobulbar blood flow
DOI: 10.5005/jp-journals-10008-1210 | Open Access | How to cite |
Glaucoma may be caused by an interplay of elevated intraocular pressure (IOP), vascular, genetic, anatomical, brain, and immune factors. The direct assessment of ocular hemodynam-ics offers promise for glaucoma detection, differentiation, and possibly new treatment modalities. All the methods currently in use to measure ocular blood flow have inherent limitations and measure different aspects of ocular blood flow. This review article attempts to provide detailed information on ocular perfu-sion pressure as well as an overview of the newly developed imaging technologies used to investigate ocular blood flow in glaucoma patients.
Spectrum of Angle Closure, Uveal Effusion Syndrome, and Nanophthalmos
[Year:2016] [Month:September-December] [Volume:10] [Number:3] [Pages:5] [Pages No:113 - 117]
Keywords: Angle closure glaucoma, Cataract, Glaucoma, Nanonophthalmos, Uveal effusion syndrome
DOI: 10.5005/jp-journals-10008-1211 | Open Access | How to cite |
Nanophthalmos, uveal effusion syndrome, and acute angle closure glaucoma (ACG) can present as a continuum in a patient, as is described here. This patient's angle closure was thought to be caused by idiopathic uveal effusion syndrome, and while there are no generally accepted diagnosis criteria for nanophthalmos, our patient fulfilled the criteria as defined by Wu.10 To prevent development of further angle closure, the decision was made to do cataract extraction as opposed to medical management.