OCTA Predicts Faster Visual Field Loss

Optical coherence tomography angiography (OCTA) has the potential to measure the progression of glaucoma because, in a study published in JAMA Ophthalmology, 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.1 OCTA measures may be useful in assessing risk in glaucoma patients.

A higher chance of having event progression and a quicker rate of visual field progression could result from density loss in the optic nerve head capillary.

Glaucoma is best controlled with the early diagnosis of visual field progression. Although OCTA can produce images of the retinal microvasculature, its application in the assessment of glaucoma is currently being studied. Reduced blood flow in the macular area and optic nerve head may be linked to glaucomatous damage. Perimetric glaucoma has been linked in the past to the thinning of the circumpapillary retinal nerve fiber layer. In primary open-angle glaucoma, this study sought to assess the strength of the relationships between initial optic nerve head capillary density loss and visual field progression, as well as between circumpapillary retinal nerve fiber layer thickness loss and visual field development.

The retrospective investigation included patients with optic nerve head imaging from both spectral-domain OCT and OCTA. In this trial, which ran from January 2015 to December 2022, patients were followed up on for an average of 5.7 (1.4) years. All subjects underwent baseline ultrasonography pachymetry assessments, semiannual intraocular pressure examinations, and annual ophthalmologic exams. If a patient exhibited glaucomatous optic neuropathy or an intraocular pressure of 22 mg Hg or more, they were suspected of having glaucoma.

Individuals who met the following criteria were considered for participation: they had to be at least eighteen years old, have a best-corrected visual acuity of 20/40 or greater, have open angles on gonioscopy, and have a refraction within 5.0 diopters spherical and 3.0 diopters cylinder. A diagnosis of Parkinson’s or Alzheimer’s disease, an axial length of 27 mm or greater, a history of intraocular surgery, concurrent retinal illnesses, and other ocular conditions precluded participation. Every OCT and OCTA picture was taken simultaneously.

This study involved 167 eyes from 109 individuals; 96 of the eyes had primary open-angle glaucoma, and 71 had glaucoma suspicious. 51.4% of the participants were female, with a mean age of 69.0 (11.1) years. 60.6% of the cohort consisted of White individuals, followed by Black or African American participants (24.8%) and Asian people (11.9%). Baseline visual field mean deviation (MD) was -2.9 (3.7) dB, while the mean baseline entire image capillary density was 42.9% (4.3).

During the mean follow-up of 2.0 (1.0) years, the mean rate of capillary density loss was -0.81 (95% CI, -0.89 to -0.74) per year. 83 and 84 eyes, representing slow and fast OCTA progressors, had mean annual capillary density loss rates of -0.45% and -1.17%, respectively.

In a univariate model, the fast OCTA progressor group (-0.25 dB/year; 95% CI, –0.32 to –0.17) showed a faster yearly visual field MD loss than the slower OCTA progressor group (–0.08 dB/year; 95% CI, –0.15 to 0.00). The OCT progressors showed the same pattern; fast OCT progressors exhibited an annual visual field MD loss that was faster than slow OCT progressors (-0.07 dB/year; 95% CI, –0.15 to 0.00) at –0.25 dB/year.

A comparable relationship was discovered between a quicker initial OCT progression and event-based visual field progression (HR, 1.70; 95% CI, 0.88-3.30). Eyes with a faster initial OCTA progression were more likely to exhibit event-based visual field progression (HR, 1.96; 95% CI, 1.04-3.69).

This study had certain shortcomings. Before the study, visual field loss might have been impacted since some of the individuals had previously had treatment for glaucoma. Because the study is being conducted at a single location, selection bias may exist. Exclusion of eyes with a visual field MD worse than –20 dB may have had an impact on the outcomes. When OCTA is used instead of OCT, there is more intra- and intervisit variability. The smaller sample size and short follow-up time may have resulted in large confidence intervals around the results.

Given that one-third of the eyes with rapid initial OCTA progression had probable future visual field progression, the researchers concluded that OCTA might be used clinically in the future.

For more information: Optical Coherence Tomography Angiography to Predict Visual Field Loss,  JAMA Ophthalmol, doi:10.1001/jamaophthalmol.2024.1120