Abstract
Purpose Intracranial pressure (ICP) and ocular perfusion pressure (OPP) are both involved with the pathogenesis of glaucoma. The orbital ICP determines a retrolaminar counter pressure that is antagonistic to the intraocular pressure (IOP). The purpose of this study is to evaluate whether the translaminar pressure difference (TLPD) and the OPP varies in glaucoma patients with different optic disc sizes.Methods In this university hospital-based, observational, cross-sectional clinical study, all patients underwent an ophthalmic evaluation. Blood pressure, height, weight, and the results of retinal nerve fiber layer examination with optical coherence tomography examination were recorded. TLPD and OPP were calculated for each patient using proxy algorithms to attain indirect surrogate parameter values. Patients' eyes were stratified into three quantiles according to optic disc sizes and the differences compared. Data from both eyes were used after using the appropriate correction for inter-eye dependency.ResultsThe sample consisted of 140 eyes of 73 patients with primary open-angle glaucoma and suspects. Patients with large disc size presented with higher TLPD as compared to those with average and small-sized discs (2.4 4.5, 2.8 3.8, and 3.7 4.7 mmHg for first, second, and third tertile, respectively (P 0.000). OPP did not vary according to the optic disc size.ConclusionGlaucoma patients with larger optic discs have higher TLPD. The pathological significance of this finding warrants further investigation.
Highlights
Presuming that there is a higher difference in the cribrosa translaminal pressure, a marked translaminar pressure gradient may damage the optic nerve, and a low orbital intracranial pressure (ICP) may be associated with the pathogenesis of glaucoma
The sample included patients who were diagnosed with Primary open-angle glaucoma (POAG) and met the following inclusion criteria: age > 40 years, any sex and ethnicity; no previous ocular lasers or incisional surgeries, except for cataract which occurred more than a year ago; optic disc with the presence of concentric increase or localized defect of the neural rim, disc hemorrhage, or a retinal nerve fiber layer (RNFL) defect; visual field defect characterized by at least three adjacent points on the pattern deviation map with P < 5% and one of the points with P < 1%, and/or pattern standard deviation (PSD) decreased with P < 5%, and/or glaucoma hemifield test (GHT) outside normal limits on a reliable exam
Patients with larger optic disc area presented a higher translaminar pressure difference (TLPD) as compared to patients with small or average discs (2.4 ± 4.5, 2.8 ± 3.8, and 3.7 ± 4.7 mmHg in the first, second, third tertile, respectively P < 0.001)
Summary
Some clinical and population studies reported that glaucoma patients have a lower ICP compared to that of normal subjects.[2, 3] From an anatomical perspective, the ICP at the orbit level and the optic nerve tissue pressure determine the retrolaminar counter pressure which is antagonistic to the IOP. It may be part of the critical translaminar gradient or a translaminar pressure difference (TLPD). There has been a debate as to whether this is an epiphenomenon or that there is an actual causal relationship between ICP and glaucoma.[4]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call