Visual Field Progression, Doubling Risk of Event Progression Associated With Density Loss in Optic Nerve

Glaucoma progression could be measured using optical coherence tomography angiography (OCTA), as rapid initial optic nerve head capillary density loss from OCTA was found to be associated with a faster rate of visual field progression and an increased risk of developing event progression, according to a study published in JAMA Ophthalmology.¹ OCTA measurements could be helpful for measuring risk in patients with glaucoma.

Glaucoma is best managed through the early detection of visual field progression. OCTA can provide images of the retinal microvasculature, but its usage in glaucoma evaluation is still being investigated. Compromised blood flow in the optic nerve head and macular region could be associated with glaucomatous damage. Previous studies have found that the thinning of the circumpapillary retinal nerve fiber layer was associated with perimetric glaucoma.² This study aimed to evaluate the strength of the associations between circumpapillary retinal nerve fiber layer thickness loss and visual field progression, as well as initial optic nerve head capillary density loss and visual field progression, in primary open-angle glaucoma.

Woman performing OCT scan | Image credit: Microgen - stock.adobe.com

Patients who had both OCTA and spectral-domain OCT optic nerve head imaging were included in the retrospective study. The study took place between January 2015 and December 2022; patients were monitored for a mean (SD) of 5.7 (1.4) years. Annual ophthalmologic exams, baseline examinations of ultrasound pachymetry, and semiannual exams of intraocular pressure were conducted on all participants. Patients were considered to have glaucoma suspect if their intraocular pressure was 22 mg Hg or higher or they had glaucomatous optic neuropathy.

Participants were included if they were aged 18 years or older, had a best-corrected visual acuity of 20/40 or better, had open angles on gonioscopy, and had a refraction within 5.0 diopters spherical and within 3.0 diopters cylinder. Participants were excluded if they had a coexisting retinal disease, a history of intraocular surgery, other ocular diseases, an axial length of 27 mm or higher, or a diagnosis of Parkinson disease or Alzheimer disease. All OCT and OCTA images were collected at the same time.

There were 167 eyes from 109 patients included in this study, of which 96 eyes had primary open-angle glaucoma and 71 eyes had glaucoma suspect. The mean age of the participants was 69.0 (11.1) years and 51.4% were women. White participants made up 60.6% of the cohort followed by 24.8% Black or African American participants and 11.9% Asian participants. The mean baseline whole image capillary density was 42.9% (4.3) and the baseline visual field mean deviation (MD) was –2.9 (3.7) dB.

Capillary density loss had a mean rate of –0.81 (95% CI, –0.89 to –0.74) per year during the mean follow-up of 2.0 (1.0) years. Slow and fast OCTA progressors made up 83 and 84 eyes with mean capillary density loss rates of –0.45% and –1.17% per year, respectively.

Faster annual visual field MD loss was found in the fast OCTA progressor group (–0.25 dB/year; 95% CI, –0.32 to –0.17) compared with the slower OCTA progressor group (–0.08 dB/year; 95% CI, –0.15 to 0.00) in a univariate model. The same was found in the OCT progressors, as fast OCT progressors had faster annual visual field MD loss (–0.25 dB/year; 95% CI, –0.33 to –0.18) compared with slow OCT progressors (–0.07 dB/year; 95% CI, –0.15 to 0.00).

Event-based visual field progression was more likely in eyes with a faster initial OCTA progression (HR, 1.96; 95% CI, 1.04-3.69), with a similar association found between a faster initial OCT progression and event-based visual field progression (HR, 1.70; 95% CI, 0.88-3.30).

There were some limitations to this study. Visual field loss could have been affected prior to the study due to included participants receiving treatment for glaucoma in the past. Selection bias is possible due to the study taking place at a single site. Eyes that had a visual field MD worse than –20 dB were excluded, which could have affected the results. Intra- and intervisit variability is greater in OCTA compared with OCT. CIs could have been wide around the findings due to the limited follow-up period and smaller cohort.

The researchers concluded that potential clinical use of OCTA should be considered in the future, as future visual field likely progression was found in one-third of the eyes that had fast initial OCTA progression.

References

1. Tansuebchueasai N, Nishida T, Moghimi S, et al. Rate of initial optic nerve head capillary density loss and risk of visual field progression. JAMA Ophthalmol. Published online May 2, 2024. doi:10.1001/jamaophthalmol.2024.0906
2. Bonavitacola J. Faster rates of GCIPL, cpRNFL thinning associated with higher risks of glaucoma. AJMC. March 9, 2023. Accessed May 8, 2024. https://www.ajmc.com/view/faster-rates-of-gcipl-cprnfl-thinning-associated-with-higher-risks-of-glaucoma