Correlation between lamina cribrosa morphology and glaucoma severity in patients with primary open-angle glaucoma

Abstract

Objectives: The objectives of the study are 1) To determine the morphological parameters of lamina cribrosa (LC), lamina cribrosa thickness (LCT) and anterior lamina cribrosa depth (ALCD) in patients with primary open angle glaucoma (POAG) and normal healthy controls. 2) To compare the lamina cribrosa thickness (LCT) and anterior lamina cribrosa depth (ALCD) in POAG cases and controls. 3) To correlate LCT and ALCD with retinal nerve fiber layer (RNFL) thickness and visual field (VF) changes in patients of primary open angle glaucoma (POAG) Methods: The study was conducted from August 2018 to April 2019. A total of 103 subjects (57 POAG cases and 46 age-matched healthy controls) were assessed for general ophthalmological investigations including intraocular pressure (IOP), axial length (AXL), steroesopic ophthalmoscopy, slit-lamp biomicroscopy, and visual field (VF) testing deducing mean deviation (VF-MD) and visual field pattern standard deviation (VF-PSD) testing utilizing enhanced depth imaging (EDI) spectral domain ocular computed tomography (SD-OCT). Results: The mean age of subjects was 65 years (65 ± 22) with more male participants. We obtained statistically significant results for intraocular pressure [IOP (20.05 ± 2.47)], AXL (24.23 ± 1.99) and VCDR (0.86 ± 0.24). We also assessed highly significant statistical values for the POAG clinical parameters of laminar dots (P-value 0.000), optic nerve head hemorrhages [ONHH P-value 0.000], parapapillary atrophy [PPA P-value 0.000] and retinal nerve fiber layer sectorial defects [RNFLD P-value 0.000]. While calculating the functional parameters of lamina cribrosa defects, significant results were procured for VF-MD and VF- PSD. The values of VF mean deviation in POAG cases were (-2.92 ± 2.52) and visual field pattern standard deviation (7.54 ± 4.69). Structural 2 variables of RNFLT (73.21 ± 13.63) and LCT (218.07 ± 79.80) were statistically significant in POAG cases as compared to the controls. We aimed for statistically significant results for deeper ALCD and thinner LCT with presence of laminar dots, PPA, ONHH, VF-MD and VF-PSD in POAG cases, in which the ALCD result was not found statistically significant. Conclusion: A thinner lamina cribrosa, quantified by lamina cribrosa thickness (LCT) in primary open-angle glaucoma (POAG) correlated significantly with the decrease in retinal nerve fiber layer thickness (RNFLT) and visual field (VF) mean deviation (VF-MD) and visual field pattern standard deviation (VF-PSD) defects. Lamina cribrosa parameters were also significantly associated with a greater axial length of the eyes (AXL), raised intraocular pressure (IOP), superior and superior-inferior sectorial retinal nerve fiber layer defects (RNFLD) and a greater vertical cup-to-disc ratio (VCDR). Laminar defects were significant in myopics. Anterior lamina cribrosa depth (ALCD) and lamina cribrosa thickness (LCT) can be estimated with precision using enhanced depth imaging spectral domain ocular coherence tomography (EDI SD-OCT). Timely evaluation and monitoring of lamina cribrosa morphology can prove prophylactic and prognostic against the deleterious effects of glaucomatous optic neuropathy (GON).