Literature review and meta-analysis of translaminar pressure difference in open-angle glaucoma

There is increasing evidence in the literature regarding translaminar pressure difference's (TPD) role in the pathophysiology of glaucoma. The optic nerve is exposed not only to intraocular pressure in the eye, but also to intracranial pressure (ICP), as it is surrounded by cerebrospinal fluid in the subarachnoid space. Although pilot studies have identified the potential importance of TPD in glaucoma, limited available data currently prevent a comprehensive description of the role that TPD may have in glaucomatous pathophysiology. In this review, we present all available qualified data from a systematic review of the literature of the role of TPD in open-angle glaucoma (OAG). PubMed (Medline), OVID Medline, ScienceDirect, SpringerLink, and all available library databases were reviewed and subsequent meta-analysis of pooled mean differences are presented where appropriate. Five papers including 396 patients met criteria for inclusion to the analysis. Importantly, we included all observational studies despite differences in ICP measurement methods, as there is no consensus regarding best-practice ICP measurements in glaucoma. Our results show that not only TPD is higher in glaucoma patients compared with healthy subjects, it is related to structural glaucomatous changes of the optic disc. Our analysis suggests further longitudinal prospective studies are needed to investigate the influence of TPD in OAG, with a goal of overcoming methodological weaknesses of previous studies

A comparative study of the effects of brinzolamide and dorzolamide on retinal oxygen saturation and ocular microcirculation in patients with primary open-angle glaucoma

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldAIMS: To assess the effects of brinzolamide and dorzolamide on ocular haemodynamics and retinal oxygen saturation in patients with primary open-angle glaucoma (OAG). METHODS: Fifteen patients with OAG were evaluated in a randomised, cross-over, double-blind study. They were treated with either brinzolamide or dorzolamide for 3 months and then crossed-over after a 4-week washout period. They were given timolol during a 4-week run-in period and during washout. The following were performed after run-in, after washout and after each treatment period: adverse events check, measurement of visual acuity, contrast sensitivity, blood pressure, heart rate, and intraocular pressure, and fundus examination. Ocular blood flow was assessed using confocal scanning laser Doppler flowmetry (HRF) and colour Doppler imaging (CDI). Retinal oxygenation levels were determined using a non-invasive measurement of haemoglobin oxygen saturation by digital photographic fundus oximetry. RESULTS: Both brinzolamide and dorzolamide reduced the number of zero-flow pixels in the retina as measured by HRF, suggesting an increase in retinal blood flow (-6.86 and -0.452 respectively) with brinzolamide treatment resulting in fewer zero-flow pixels than dorzolamide (-6.41) (p = 0.024). Both brinzolamide and dorzolamide increased oxygen saturation in the retina as measured by photographic retinal oximetry in the superior (0.82 (p = 0.002) and 0.87 (p = 0.005)) and inferior (0.88 (p = 0.035) and 0.82 (p = 0.002)) retinal veins. No significant changes were found in CDI measurements of the retrobulbar blood supply during either treatment. CONCLUSION: This pilot study suggests that brinzolamide and dorzolamide may increase retinal oxygen saturation in patients with OAG

Optic nerve head diurnal vessel density variations in glaucoma and ocular hypertension measured by optical coherence tomography angiography

Background/aims: To evaluate diurnal variations in optic nerve head (ONH) vessel density assessed by optical coherence tomography angiography (OCT-A) in healthy subjects, ocular hypertension (OHT), and open-angle glaucoma (OAG) patients. Methods: Forty subjects (OAG, 21; OHT, 6; healthy, 13) were assessed for vessel density percentage (VD%) and flow index in the ONH (NH VD%, NH index), and in the radial peripapillary capillary layer (RPC VD%, RPC index) at 9:00, 11:00, 14:00, 16:00, and 18:00 on a single day. Repeated measures ANOVAs were used to test for changes in the parameters measured at multiple time points. Results: All OCT-A parameters analyzed at the different time points were statistically lower in the OAG patients compared to both the OHT and healthy groups (p 0.05). Conclusion: In healthy subjects, OHT and OAG patients, the variations in the OCT-A derived parameters were relatively small. These results suggest that in the clinical practice the OCT-A assessment can be performed independently of the time of the day, contrasting IOP evaluation