Early Retinal Vascular Density Deficiency May Indicate Risk of Visual Field Loss in Glaucoma

Glaucoma is characterized by progressive visual field (VF) loss and is the leading cause of blindness worldwide. A recent study assessed the association between the rate of early retinal vascular density (VD) loss at initial follow-up and VF loss over time in patients who have glaucoma and patients suspected of having glaucoma. Findings suggest that faster VD loss at initial follow-up is linked to faster VF loss over time.

VF testing is a key aspect of follow-up in glaucoma throughout treatment because VF degeneration significantly affects patient quality of life. As such, diagnostic tests have been developed to assess a patient’s risk of subsequent VF loss—a crucial component for ensuring timely observation and treatment for glaucoma.

Past research shows that structural parameters, such as decreased VD determined by optical coherence tomography angiography (OCTA), might be evident before future functional defects. Decreased VD on OCTA has also been associated with decreased retinal nerve fiber layer thickness measured with optical coherence tomography (OCT), the study authors noted.

Although these associations have been identified, past research has not investigated the implications of early VD decrease and subsequent VF loss, to the authors’ knowledge. The current study, published in JAMA Ophthalmology, aimed to provide insight into the relationship between decreased VD and later VF loss specifically.

The retrospective cohort study included 86 eyes with primary open-angle glaucoma and 38 eyes suspected of having glaucoma. There were 82 patients, all of whom followed up at a tertiary glaucoma center for a mean of 4 years. There were equal numbers of men and women in the cohort.

Each patient underwent 3 OCTA scans early in the study, which were used to gauge the rate of VD loss. VF loss was determined by the mean deviation over the entire follow-up, which included annual comprehensive ophthalmologic evaluation that included best-corrected visual acuity, slitlamp biomicroscopy, Goldmann applanation tonometry, gonioscopy, dilated fundus examination, stereoscopic optic disc photography, and ultrasonographic pachymetry in both eyes. Intraocular pressure (IOP), OCTA imaging, and standard automated perimetry testing were evaluated semiannually.

At a mean initial follow-up at 2 years, the annual VD change rate was –0.80% (95% CI, –0.88% to –0.72%). Fast progression was defined as VD loss of 0.75% or greater, and 62 eyes fell into this category. Slow progression was defined as an annual rate of less than 0.75%, and 62 eyes fell into this category. The slow-progressing group saw an annual VF loss of –0.15 dB (95% CI, –0.29 to –0.01 dB), while the fast-progressing group saw an annual VF loss of –0.43 dB (95% CI, –0.58 to –0.29 dB).

After adjusting to include the concurrent mean VF deviation rate, which was –0.17 dB, the group who showed fast progression determined by OCTA had a faster overall rate of VF loss during follow-up. In a univariable model, higher mean IOP during follow-up, worse baseline VF mean deviation, and faster concurrent VF mean deviation rate were also associated with overall VF mean deviation in the study cohort.

Despite the study’s limitations, including a limited number of OCTA scans, lower reproducibility with OCTA vs OCT, and varied preexisting courses of glaucoma across the cohort, the study authors conclude that VD loss at initial follow-up was associated with both concurrent and subsequent VF loss in the cohort at extended follow-up.

The findings support the use of OCTA for monitoring rate of VD loss and potential VF progression in patients with glaucoma. Further studies confirming that OCTA fast progressors are at a higher risk of functional loss would indicate the clinical relevance of these findings.

Reference

Nishida T, Moghimi S, Wu J-H, et al. Association of initial optical coherence tomography angiography vessel density loss with Faster visual field loss in glaucoma. JAMA Ophthalmol. Published online February 24, 2022. doi:10.1001/jamaophthalmol.2021.6433