Optic Nerve Head Characteristics in Chronic Angle Closure Glaucoma Detected by Swept-Source OCT

ABSTRACT

Purpose: To compare structural features in prelaminar and laminar tissues of the optic nerve head (ONH) in chronic angle closure glaucoma (CACG), primary open angle glaucoma (POAG), and control subjects.

Materials and Methods: ONH imaging was performed using swept-source optical coherence tomography (SS-OCT) for measurements of minimum rim width at Bruch’s membrane opening (BMO-MRW), horizontal, and vertical lamina cribrosa depth (LCD). Prelaminar defects, categorized as hole and wedge, and lamina cribrosa (LC) defects were identified. Enhanced depth imaging spectral domain OCT (EDI-OCT) customized to perform high-resolution volume scans was used in conjunction to further characterize prelaminar holes. One eye per subject was analyzed.

Results: Eighty subjects (20 CACG, 40 POAG, and 20 controls) were included in the study. CACG and POAG groups had similar mean deviation on Humphrey visual field testing (−6.9 ± 5.1 vs. −6.3 ± 6.0 dB, p > 0.05) and IOP on the day of imaging (14.0 ± 3.1 vs. 13.8 ± 2.7 mmHg, p > 0.05). Thinnest and global BMO-MRW in CACG (120.3 ± 44.8, 225.5 ± 53.9 μm) and POAG (109.7 ± 56.3, 213.8 ± 59.7 μm) groups were lower than controls (200.1 ± 40.8, 308.3 ± 70.8 μm; p < 0.001 for both). Prelaminar holes were most frequent in CACG (65.0%) than POAG (25.0%, p=0.008) or control groups (20.0%, p=0.01). After adjusting for demographic and ophthalmic covariates, CACG was associated with increased odds of having prelaminar holes compared to POAG (odds ratio, 9.79; 95% CI, 2.12–45.19; p=0.003). Hole volume was similar between CACG and POAG (p > 0.05), but the CACG group had more holes per scan than POAG (maximum 2.5 ± 1.9 vs. 1.2 ± 0.4, p=0.02). Prelaminar wedge defects were less common in the CACG than the POAG group (5.0% vs. 37.5%, p=0.02). The CACG group did not differ from controls in laminar characteristics, such as LCD and LC defects.

Conclusions: SS-OCT evaluation of the ONH revealed more frequent prelaminar holes in CACG compared to POAG and control patients.

KEYWORDS:

• Chronic angle closure glaucoma
• glaucoma imaging
• optic nerve head
• prelaminar defect
• swept-source optical coherence tomography

Acknowledgments

The authors thank the Massachusetts Eye and Ear Fluorescein Laboratory Photographers and the Massachusetts Eye and Ear study coordinators.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding

This work was supported by the Harvard Glaucoma Center of Excellence and the Miller Research Funds at the Massachusetts Eye and Ear. A.V.T., L.R.P. and L.Q.S. were supported by the Harvard Glaucoma Center of Excellence. L.R.P. was supported by a Harvard Medical School Distinguished Ophthalmology Scholar Award. L.Q.S. was supported by the Eleanor and Miles Shore Fellowship, Harvard Medical School. E.I.P. was supported by the Boston Keratoprosthesis Research Fund.

Additional information

Funding

This work was supported by the Harvard Glaucoma Center of Excellence and the Miller Research Funds at the Massachusetts Eye and Ear. A.V.T., L.R.P. and L.Q.S. were supported by the Harvard Glaucoma Center of Excellence. L.R.P. was supported by a Harvard Medical School Distinguished Ophthalmology Scholar Award. L.Q.S. was supported by the Eleanor and Miles Shore Fellowship, Harvard Medical School. E.I.P. was supported by the Boston Keratoprosthesis Research Fund.