Clinical use of both OCT, OCT angiography may help assess risk for glaucoma progression
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Key takeaways:
- Fast OCT and OCT angiography progressors were associated with more rapid visual field loss.
- Fast OCTA progressing eyes were most likely to have visual field progression.
Faster initial capillary density loss was associated with more rapid visual field progression and increased risk for event progression, prompting researchers to suggest the addition of OCT angiography for risk assessment in glaucoma.
“Early detection of visual field progression is vital for effective management of glaucoma,” Natchada Tansuebchueasai, MD, and colleagues from Shiley Eye Institute at the University of California, San Diego, wrote in JAMA Ophthalmology. “Extensive research has focused on the predictive capabilities of structural optic nerve and retinal nerve fiber layer parameters and their association with visual field loss.”
Researchers conducted a retrospective study of a longitudinal cohort at a glaucoma referral center to determine the association between the rate of initial optic nerve head capillary density loss and visual field progression.
They included 167 eyes with suspected glaucoma (n = 71 eyes) and primary open-angle glaucoma (n = 96 eyes) from 109 patients (mean age, 69 years; 48.6% men) who underwent OCT angiography (OCTA) and spectral-domain OCT for optic nerve head capillary density and retinal nerve fiber layer (RNFL) thickness analysis. Participants were monitored from January 2015 to December 2022 (mean, 5.7 years).
According to results, the mean whole image capillary density at baseline was 42.9%, and the mean visual field mean deviation was –2.9 dB. During the initial mean 2 years of follow-up, the mean rate of capillary density loss was –0.81 per year, and the mean rate of RNFL thinning was –0.34 µm per year.
The researchers categorized 83 eyes as slow OCTA progressors with a mean capillary density loss of –0.45% per year and 84 eyes as fast progressors with a mean capillary density loss of –1.17% per year (mean difference, –0.72% per year; P < .001).
They also identified 83 eyes as slow OCT progressors with mean RNFL thinning of –0.09 µm per year and 84 eyes as fast progressors with mean RNFL thinning of –0.6 µm per year (mean difference, –0.51 µm per year; P < .001).
The fast OCTA and OCT progressors had more rapid visual field loss compared with the slow progressors (mean differences, –0.18 dB/year; P = .004 and –0.17 dB/year; P = .002, respectively), and fast OCTA-progressing eyes were more likely to have visual field progression (HR = 1.96; P = .04).
Of eyes with fast OCTA and OCT progression, 32.7% developed subsequent visual field likely progression, while 21.9% that were fast OCTA but slow OCT progressors had this development.
“Fast initial capillary density loss was associated with faster rate of visual field progression and a greater chance of developing event visual field progression over an extended follow-up,” Tansuebchueasai and colleagues wrote. “One-third of eyes that had fast initial OCT and OCTA progression developed future visual field likely progression. Both trend and event analysis findings support the consideration of potential clinical use of OCTA along with OCT for estimating the risk of glaucoma progression.”
Perspective
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Our mission as glaucoma providers can be streamlined into determining whether our patient’s glaucoma is progressing, how fast it progresses and how likely it is that it will progress to vision loss.
Figuring out who on the front end is most likely to progress and doing so early in the disease course should enhance our odds of preserving vision and has ultimately led to the search for prognostic biomarkers. OCT structural biomarkers such as RNFL and ganglion cell-inner plexiform layer are well-known, but the recent development of OCTA has raised the possibility that we may be able to use microvascular biomarkers as meaningfully as their structural counterparts.
Tansuebchueasai and colleagues calculated the rates of initial optic nerve head capillary density loss to determine if changes were associated with future visual field progression. They found that faster initial loss of capillary density was, indeed, associated with more rapid rates of visual field progression, and suggested this provides further evidence of OCTA’s potential to provide prognostic information complementary to OCT.
Previous OCTA studies have shown that the vascular-function relationship is stronger than the structure-function relationship, and this has led to excitement that OCTA has the potential to become a unique addition to our glaucoma calculus. In this study, faster initial RNFL loss also was associated with more rapid visual field progression, and therefore, in this case, OCTA does not appear to further advance our knowledge beyond conventional testing.
As the authors point out, further studies will help us understand how clinically relevant OCTA can be, but the potential is there.
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Tansuebchueasai N, et al. JAMA Ophthalmol. 2024:doi:10.1001/jamaophthalmol.2024.0906.
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