Abstract
Purpose:
While posterior displacement of the anterior laminar surface (ALS), reduction of neuroretinal rim and thinning of the retinal nerve fiber layer (RNFL) have been reported in experimental glaucoma, longitudinal changes of the laminar cribrosa in patients with chronic glaucoma have not been investigated. This is a 3-year prospective study following pre-laminar and laminar displacement, and pre-laminar tissue thickness (PLTT) in patients with progressive RNFL thinning.
Methods:
SD-OCT images of 27 eyes of 20 glaucoma patients (each eye had 6 radial scans centered at the optic disc for each visit) who had been followed 4 monthly for a mean of 47.15 months (range: 35 - 54 months) and had significant RNFL thinning (detected by OCT) were exported for measurement of (1) pre-laminar and (2) laminar displacement and (3) neuroretinal rim width after manually detecting the neural canal opening and the boundaries of anterior laminar and laminar surfaces. The mean values of each parameter were computed form the 6 scans. Progression was defined with reference to the linear regression analysis.
Results:
7 eyes (26.0%) showed pre-laminar displacement [4 had posterior and 3 had anterior displacement (1 had a history of glaucoma surgery)], 12 (44.4%) had laminar displacement [8 had posterior and 4 had anterior displacement (1 had a history of glaucoma surgery)], and 12 (44.4%) had reduction in neuroretinal rim width. All the 7 eyes with pre-laminar displacement also demonstrated corresponding laminar displacement. 3 eyes (11.1%) had thinning of pre-laminar tissue thickness. 9 eyes (33.3%) did not show significant changes in any of the neuroretinal rim and laminar / pre-laminar parameters despite having significant progressive RNFL thinning during the follow-up.
Conclusions:
Pre-laminar and laminar displacement can be detected with SD-OCT in chronic glaucoma patients. Progressive RNFL thinning may occur without concomitant laminar and pre-laminar changes.
Keywords: 550 imaging/image analysis: clinical