Inner fluid volume and its role in macular hole repair

Reviewed by Kotaro Tsuboi, MD.

Location is everything, especially in the eye.

Inner fluid volume measured by optical coherence tomography (OCT) differs significantly in its amount, shape and distribution compared with outer fluid volume. It also is associated with larger macular holes and poorer postoperative vision in contrast with outer fluid volume.

These findings suggest that inner fluid volume represents a retinal degenerative change associated with more advanced macular holes, according to Kotaro Tsuboi, MD, a visiting scholar from Aichi Medical University in Nagakute, Aichi, Japan, at Oregon Health & Science University.

The results are from a study in which investigators took a retrospective look at intraretinal cystoid spaces, which are often present next to macular holes, using the AngioVue OCT angiography (OCTA) and Avanti RTVue XR (Optovue). All study patients had undergone a successful surgery to close a macular hole that included pars plana vitrectomy with internal limiting membrane peeling.

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The OCTA software in the Avanti machine produced volumetric data and custom software,1 and generated volume-rendering OCT images of the intraretinal fluid spaces, Tsuboi explained.

Results

The study included 42 eyes of 39 patients. Using the International Vitreomacular Traction Study classification, investigators classified the macular holes as small in 11 eyes (26%), medium in 11 eyes (26%) and large in 20 eyes (48%). Sixteen eyes (38%) had vitreomacular traction (VMT). Of the 42 eyes, 39 (93%) underwent combined phacovitrectomy and all eyes were pseudophakic postoperatively.

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Importantly, large macular holes were associated with increased inner fluid volume compared with small macular holes, a difference that reached significance (P = .0030). No differences in outer fluid volume were seen in association with the size of the macular holes, Tsuboi reported. In addition, VMT did not seem to drive the inner and outer fluid volumes, which were similar in eyes with and without VMT.

Inner fluid volume and minimal macular hole size had a significant effect on postoperative visual acuity (Pearson r [r] = 0.44, P = .0033 and r = 0.43, P = .0045, respectively), whereas basal macular hole size (r = 0.21, P = .19) and outer fluid volume (r = –0.17, P = .27) did not. The multivariate analysis found that inner fluid volume was the only significant factor affecting the postoperative 12-month visual acuity (r = 0.41, P = .021).

Inner fluids are shown in green and outer fluids in red. Volume-rendering OCT shows the outer FV is greater than the inner FV. En face OCT demonstrates the different distribution pattern between inner and outer fluids. (Images courtesy of Kotaro Tsuboi, MD)

optical coherence tomography = OCT; fluid volume = FV

The main takeaways from the study were that OCT showed that inner fluid volume differed significantly in amount, shape and distribution compared with outer fluid volume; it was associated significantly with large macular holes and poorer postoperative vision in contrast with outer fluid volume.

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Further, inner fluid volume may represent dysfunction of the Müller cells and a degenerative change associated with more advanced macular holes.

Reference

Guo Y, Hormel TT, Xiong H, Wang J, Hwang TS, Jia Y. Automated segmentation of retinal fluid volumes from structural and angiographic optical coherence tomography using deep learning. Transl Vis Sci Technol. 2020;9(2):54. doi:10.1167/tvst.9.2.54

Kotaro Tsuboi, MD

E: kotarotsuboi@gmail.com

This article was adapted from Tsuboi’s presentation at the Association for Research in Vision and Ophthalmology 2021 virtual annual meeting. He has no financial interest in this subject matter.

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