Comparison of Lamina Cribrosa Morphology in Normal Tension Glaucoma and Autosomal-Dominant Optic Atrophy

Abstract

Purpose: To compare lamina cribrosa (LC) morphology in patients with normal tension glaucoma (NTG) and autosomal-dominant optic atrophy (ADOA).

Methods: This cross-sectional study matched 24 patients diagnosed with ADOA (24 eyes) by age and retinal nerve fiber layer thickness with 48 patients diagnosed with NTG (48 eyes) by age with 48 healthy controls (48 eyes). Optic nerve heads were scanned by enhanced-depth imaging (EDI) optical coherence tomography (OCT). The LC curvature index (LCCI) and LC depth (LCD) on B-scan images obtained using EDI-OCT were measured at seven locations spaced equidistantly across the vertical optic disc diameter and compared among the NTG, ADOA, and control groups.

Results: Mean LCCI and LCD were significantly greater in NTG than in ADOA and healthy eyes (P < 0.001 each) but did not differ significantly in ADOA and healthy eyes.

Conclusions: NTG eyes have a more posteriorly curved and deeper LC than ADOA and healthy eyes. This finding provides insight into the role of LC morphology in NTG and provides a clinical clue to distinguish between NTG and ADOA.

Figure 1.

Measurements of LCD and LCCI. (A) Disc photograph showing seven horizontal green lines indicating the locations at which the measurements were taken. (B) Measurement of the LCD from the reference line connecting the two BMO points to the anterior surface of the LC. LCD was defined as the distance from this reference line at the maximally depressed point. (C) Determination of LCCI by dividing the LCCD within the BMO by the width of the anterior LC surface reference line (W), and then multiplying by 100.

Figure 2.

Variations in LCD (A) and LCCI (B) in the different planes and groups of patients, with groups 1, 2, and 3 representing the ADOA, NTG, and health control groups, respectively. Error bars indicate the standard error of the mean.

Figure 3.

Representative eyes showing the LC morphology in (A–C) an eye with ADOA in a 72-year-old woman, and (D–F) an eye with NTG in a 77-year-old woman. (A and D) Optic disc photographs showing temporal pallor of the optic disc. (B and E) B-scan images at plane 6, indicated by the green lines in the optic disc photographs. (C and F) OCT circumpapillary scanning of the RNFL. (C) RNFL thickness reduction of the inferotemporal region. (F) RNFL thickness reduction in the temporal region.