Superficial Capillary Plexus Vessel Density Can Provide Key Glaucoma Diagnostic Metric

Researchers have found that examining the macula’s superficial capillary plexus (SCP) vessel density provides more information than deep capillary plexus (DCP) vessel density when diagnosing glaucoma. These findings were published in the Journal of Glaucoma.

While SCP vessel density measurements are commonly assessed via optical coherence tomography angiography (OCT-A), few studies have looked at deep capillary plexus vessel density, according to researchers. This is due, in part, to the presence of projection artifacts. However, there are now automated tools to remove these artifacts.

To evaluate the diagnostic accuracy of examining SCP vessel density and projection-resolved DCP vessel density, investigators assessed high-density OCT-A images of 68 eyes of 44 healthy patients, 26 eyes of 16 patients considered preperimetric glaucoma suspects, and 161 eyes of 124 patients diagnosed with glaucoma. 

The mean whole image vessel density (wiVD; percent of the area occupied by vessels containing flowing blood) in the SCP layer was highest in healthy eyes (49.7%), followed by glaucoma-suspect eyes (46.0%), and glaucoma eyes (40.9%) (P <.001). Mean wiVD in the DCP layer was similar in healthy (50.6%), glaucoma-suspect (47.3%), and glaucoma eyes (45.7%) (P =.925). Diagnostic accuracy of both ganglion cell complex (GCC) thickness and SCP wiVD was significantly higher than DCP wiVD for classifying healthy and glaucoma eyes [adjusted area under the receiver operating characteristic curve (95% confidence interval): GCC = 0.86 (0.72, 0.94), SCP= 0.80 (0.66, 0.91) and DCP=0.44 (0.30, 0.57)] (P <.001).

Researchers conclude that deep capillary plexus vessel density measurements did not help differentiate between healthy, glaucoma-suspect and glaucoma. However, the imperfect nature of the artifact-removal algorithm may play a role.

Researchers note several limitations to their study, including that the projection artifact removal algorithm does not remove all artifacts, the sample size of the glaucoma-suspect group was smaller than the healthy and glaucoma-positive groups, a larger proportion of glaucoma and suspect eyes were excluded from the study due to poor quality scans, and GCC/SCP thickness wasn’t compared with the DCP due to lack of deep layer thickness data using the current software. Lastly, topical glaucoma and systemic medications might influence vessel density.

Disclosure: Multiple study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.  

Reference

El-Nimri NW, Manalastas PIC, Zangwill LM, et al. Superficial and deep macula vessel density in healthy, glaucoma suspect, and glaucoma eyes. J Glaucoma. 2021;30(6):e276-e284. doi:10.1097/IJG.0000000000001860.