Macular vessel density a useful marker for glaucoma progression

This prospective longitudinal study characterized the morphologic and vascular changes in glaucomatous eyes.

Study design

Researchers used OCT angiography to evaluate vessel density and structural thickness of 139 eyes: 23 healthy, 36 preperimetric and 80 primary open-angle glaucoma (POAG). The mean follow-up time ranged from 2 to 2.6 years. The associations between the rates of changes in ganglion cell complex (GCC) thickness and vessel density and potential factors were evaluated.

Outcomes

All 3 groups demonstrated significant rates of GCC thinning and macular vessel density loss. The rates of GCC and macular vessel thinning in the healthy and preperimetric groups were comparable. However, in the POAG group, the decrease in macular vessel density was significantly faster than GCC thinning (-7.12%/year vs. -2.13%/year). Faster macular vessel density decline—but not GCC thinning—significantly associated with worse glaucoma severity. Although IOP affected the rate of GCC thinning in all groups, it did not track with macular vessel density decrease.

Limitations

The patient groups were not matched based on any characteristics or parameter and differing characteristics among the 3 diagnostic groups could have potentially contributed to the study results. The study scans were 3x3 mm² but larger 6x6 mm² scans are available and could lead to higher diagnostic accuracy, but longitudinal data for larger scans are not yet available. The relationship between GCC thinning, macular vessel density and the stage of disease severity was not assessed due to the limited sample size of moderate and advanced POAG cases (14 and 5, respectively).

Clinical significance

The findings suggest that OCT angiography may be particularly useful for evaluating glaucoma progression in advanced disease. Further studies are needed to assess the optimum number of tests to evaluate progressive changes seen on OCT angiography.