Abstract
PurposeTo measure horizontal and vertical lamina cribrosa (LC) tilt angles and investigate associated factors using prototype optical coherence tomography (OCT) with a broad wavelength laser light source.DesignCross sectional study.MethodsTwenty-eight no glaucoma eyes (from 15 subjects) and 25 glaucoma eyes (from 14 patients) were enrolled. A total of 300 optic nerve head B-scans were obtained in 10 µm steps and the inner edge of Bruch's membrane opening (BMO) was identified as the reference plane. The vertical and horizontal angles between BMO line and approximate the best-fitting line for the surface of the LC were measured and potential associated factors were estimated with univariate and multivariate logistic regression analyses.ResultsThe median (interquartile range) horizontal and vertical tilt angles were 7.10 (2.43–11.45) degrees and 4.15 (2.60–6.85) degrees in eyes without glaucoma and 8.50 (4.40–14.10) degrees and 9.30 (6.90–14.15) degrees in glaucoma eyes, respectively. The refractive errors had a statistically significant association with horizontal LC tilt angles (coefficients, −1.53 per diopter) and glaucoma had a significant correlation with vertical tilt angles (coefficients, 6.56) using multiple logistic regression analysis (p<0.001).ConclusionsOCT allowed evaluation of the internal tilting of the LC compared with the BMO. The horizontal internal LC tilt angle was correlated with refractive errors, corresponding to myopic physiological changes, and vertical internal LC tilt was correlated with glaucoma, corresponding to glaucomatous pathological changes. These parameters have important implications for investigation of the correlation between myopia, glaucoma and LC morphological features.
Highlights
The lamina cribrosa (LC) has been known to play a critical role in the pathogenesis of glaucoma. [1,2,3] The LC is a porous connective tissue through which retinal ganglion cell axon bundles travel in transit to the orbital portion of the optic nerve
Tilted disc and peripapillary atrophy reportedly develops in association with childhood age and a greater myopic shift. [14,15,16] Park et al reported that tilted and torsioned discs were more prevalent in myopic eyes, and the direction of the optic disc torsion was related to the location of visual field (VF) defect in patients with normal tension glaucoma based on fundus photograph analysis
To be eligible for the study, glaucoma patients had to have been previously diagnosed with primary open angle glaucoma (POAG) that fulfilled the criteria; i.e., characteristic glaucomatous optic nerve head (ONH) damage such as localized or diffuse neuroretinal rim thinning associated with glaucomatous loss of the visual field in accordance with the criteria of Anderson and Patella [19] using the Humphrey Field Analyzer (HFA; Carl Zeiss Meditec, Dublin, CA) and the standard 30-2 program of the Swedish interactive threshold algorithm (SITA)
Summary
The lamina cribrosa (LC) has been known to play a critical role in the pathogenesis of glaucoma. [1,2,3] The LC is a porous connective tissue through which retinal ganglion cell axon bundles travel in transit to the orbital portion of the optic nerve. Histopathological studies reported various changes in the LC structure, such as thinning, posterior displacement, and less connective tissue, which are thought to be associated with key mechanisms by which the retinal nerve fibers are damaged in glaucoma. Recent studies using SD-OCT devices revealed structural and dimensional changes associated with glaucomatous patients, such as thinning, and posterior displacement and its reversal after IOP reduction. [14,15,16] Park et al reported that tilted and torsioned discs were more prevalent in myopic eyes, and the direction of the optic disc torsion was related to the location of visual field (VF) defect in patients with normal tension glaucoma based on fundus photograph analysis. Tilted disc and peripapillary atrophy reportedly develops in association with childhood age and a greater myopic shift. [14,15,16] Park et al reported that tilted and torsioned discs were more prevalent in myopic eyes, and the direction of the optic disc torsion was related to the location of visual field (VF) defect in patients with normal tension glaucoma based on fundus photograph analysis. [17] These interesting findings raise a question with regard to whether there is asymmetrical deformation of the LC in glaucomatous patients
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