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Editors Selection IGR 20-2
Prognostic factors: Predicting visual field loss from choroidal vascular dropout
Comment by Min Hee Suh on:
91971 An Increased Choroidal Microvasculature Dropout Size is Associated With Progressive Visual Field Loss in Open-Angle Glaucoma, Lee JY; Shin JW; Song MK et al., American Journal of Ophthalmology, 2021; 223: 205-219
The advent of the optical coherence tomography angiography (OCTA) enabled in-vivo assessment of deep-layer microvasculature defined as choriocapillaris or vessels within the scleral flange. Moreover, there is accumulating evidence that OCTA-derived parapapillary deep-layer microvasculature dropout (MvD-P) is a characteristic sign suggestive of glaucoma progression.1-3 A recent study by Lee et al. adds to the literature that angular enlargement of the MvD-P is positively associated with the rate of visual field (VF) progression. This highlights the pathogenic role of MvD-P in the progressive change of glaucomatous optic neuropathy.
Interestingly, the extent of the MvD-P angular enlargement was significantly larger in the VF progressor than in the VF non-progressor, while the rate of RNFL thinning did not differ between the two groups. Given that the study population of this study had moderate to advanced disease severity, RNFL may be limited in detecting progression due to the floor effect. MvD-P enlargement can serve as a useful structural parameter indicating disease progression, especially in moderate to advanced glaucoma.
However, the temporal relationship between the MvD-P enlargement and glaucoma progression remains to be elucidated. Decreased metabolic need due to the progressive loss of the retinal ganglion cell (RGC) may lead to reduced ocular perfusion, resulting in the enlargement of the dropout. On the other hand, functional deterioration of the RGC can be derived from the hypo-perfusion of the optic nerve head.4 Future prospective longitudinal studies are needed to clarify the causative role of the parapapillary deep-layer microvasculature dropout in the glaucoma progression.
References
- Kwon JM, Weinreb RN, Zangwill LM, Suh MH. Parapapillary Deep-Layer Microvasculature Dropout and Visual Field Progression in Glaucoma. Am J Ophthalmol. 2019;200:65-75.
- Kim JA, Lee EJ, Kim TW. Evaluation of Parapapillary Choroidal Microvasculature Dropout and Progressive Retinal Nerve Fiber Layer Thinning in Patients With Glaucoma. JAMA Ophthalmol. 2019;137(7):810-816.
- Park HY, Shin DY, Jeon SJ, Park CK. Association Between Parapapillary Choroidal Vessel Density Measured With Optical Coherence Tomography Angiography and Future Visual Field Progression in Patients With Glaucoma. JAMA Ophthalmol. 2019;137(6):681-688.
- Flammer J, Orgul S, Costa VP, et al. The Impact of Ocular Blood Flow in Glaucoma. Prog Retin Eye Res 2002; 21(4): 359-93.
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