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Editors Selection IGR 22-3

Clinical Examination Methods: Macular Microvascular Density and Visual Acuity in Glaucoma

Jin Wook Jeoung

Comment by Jin Wook Jeoung on:

96059 Relationship Between Macular Microvasculature and Visual Acuity in Advanced and Severe Glaucoma, Hsia Y; Wang TH; Huang JY et al., American Journal of Ophthalmology, 2021; 236: 154-163


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In the late stage of glaucoma, the structural parameters including the retinal nerve fiber layer (RNFL) and ganglion cell complex can reach the measurement floor, restricting the usefulness of OCT for detecting disease progression beyond a minimum practical value.1 Previous studies have shown that vessel density had a lower value for the measurement floor and was promising for disease monitoring in more advanced stages.2,3 Considering the lower cutoff values for OCT angiography-derived vessel density, it is reasonable to hypothesize that peripapillary and macular vessel density might exhibit stronger structure- function relationships than the RNFL and ganglion cell complex in patients with advanced glaucoma.

Hsia et al.4 evaluated the correlation between structural parameters and visual acuity in advanced glaucoma. A total of 238 eyes from 238 patients were divided into an advanced (mean deviation of 24-2 visual field tests from −12.01 to −20.0 dB) and severe (< −20 dB) glaucoma group. This study showed that macular vessel density showed a better correlation with visual acuity than other structural parameters. Both deep and superficial macular vessel density showed the highest correlation with visual acuity in advanced glaucoma, and only the deep nasal grid vessel density showed the highest correlation with visual acuity in severe glaucoma. These findings suggest that deep macular vessel density, especially nasal grid, may be a promising structural parameter in severe glaucoma.

Deep macular vessel density, especially nasal grid, may be a promising structural parameter in severe glaucoma

As pointed out by the authors, several factors limit this study's generalizability and clinical relevance. Ocular and systemic conditions, such as subclinical age-related macular degeneration, diabetes mellitus, cardiovascular disease, and the use of systemic medication, may cause macular vessel density changes. Possible projection artifacts may bias the analysis of deep macular vessel density. In spite of these limitations, this paper is important in clarifying the relationship between structural parameters and visual acuity in patients with advanced and severe glaucoma based on the relatively large cohort. Considering the test-retest variability of OCT angiography, further studies with more reliable and reproducible algorithms may be necessary to elucidate the correlation between macular vessel density and central visual function.

References

  1. Bowd C, Zangwill LM, Weinreb RN, Medeiros FA, Belghith A. Estimating optical coherence tomography structural measurement floors to improve detection of progression in advanced glaucoma. Am J Ophthalmol. 2017;175:37-44.
  2. Yarmohammadi A, Zangwill LM, Diniz-Filho A, et al. Relationship between optical coherence tomography angiography vessel density and severity of visual field loss in glaucoma. Ophthalmology. 2016;123(12):2498-2508.
  3. Moghimi S, Bowd C, Zangwill LM, et al. Measurement floors and dynamic ranges of OCT and OCT angiography in glaucoma. Ophthalmology. 2019;126(7):980-988.
  4. Hsia Y, Wang TH, Huang JY, Su CC. Relationship between macular microvasculature and visual acuity in advanced and severe glaucoma. Am J Ophthalmol. 2021;236:154-163.


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