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Comment
. 2023 May;37(7):1470-1478.
doi: 10.1038/s41433-022-02158-4. Epub 2022 Jul 6.

Effects of physiological fluctuations on the estimation of vascular flow in eyes with idiopathic macular pucker

Rino Frisina  1 , Gabriella De Salvo  2 , Luigi Tozzi  1 , Irene Gius  1 , Jean-Yves Sahyoun  3 , Barbara Parolini  4 , Alessandro Meduri  5
Affiliations
Comment

Effects of physiological fluctuations on the estimation of vascular flow in eyes with idiopathic macular pucker

Rino Frisina et al. Eye (Lond). 2023 May.

Abstract

Objectives: To evaluate the macular vascular flow in eyes with idiopathic macular pucker (EyeiMP), pre and post pars plana vitrectomy with epiretinal and limiting membranes peeling, and to compare it with the vascular flow in the healthy fellow eyes (Eyefellow), taken as physiological reference value.

Methods: 40 eyes of 40 patients were recruited. Best-corrected visual acuity (BCVA) was evaluated. Spectral domain optical coherence tomography (SD-OCT) and OCT-angiography parameters were central foveal thickness (CFT), choroidal thickness (CT), foveal avascular zone (FAZ) area, vessel area density (VAD), vessel length fraction (VLF), vessel density index (VDI) of superficial capillary plexus (SCP) and deep vascular complex (DVC), choriocapillaris (CC) flow. Absolute and relative difference calculation was applied to evaluate macular vascular flow in EyeiMP adjusted for physiological changes detected in Eyefellow.

Follow-up: 6 months.

Results: BCVA improved (p = 0.003) in all cases following surgery. CFT reduced postoperatively (p = 0.0138). FAZ area was smaller in EyeiMP than Eyefellow (p = 0.0071) preoperatively and postoperatively it shrank further (p = 0.0027). After surgery, inverse correlation between FAZ area and BCVA was detected (r-0.683). VAD of SCP was pre- and post-operatively higher in EyeiMP than Eyefellow (baseline p = 0.0344, 6th month p = 0.0466). Relative difference of VDI of SCP (p = 0.0096) and CC flow (p = 0.0013) at 6 months reduced. DVC flow changed significantly only in Eyefellow. CT increased post-operatively in both EyeiMP (p = 0.0345) and Eyefellow (p = 0.00423), but relative difference did not change.

Conclusions: Vascular flow indices monitoring demonstrated significant changes in both eyes: EyeiMP and Eyefellow. Relative difference of vascular flow provided objective estimate of changes due to iMP surgery taking into account physiological changes in Eyefellow.

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Conflict of interest statement

RF, LT, IG, JYS, BP, and AM certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or nonfinancial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials. GDS received honoraria and consultancies fees outside the current work from the following companies: Allergan Abbvie, Apellis, Bayer, Boehringer Ingelheim, Heidelberg Engineering, Novartis.

Figures

Fig. 1
Fig. 1. Example of calculation of absolute and relative difference.
a Graph shows a calculation of the absolute and relative difference. Healthy fellow eye (Eyefellow) has a flow of 7 units at baseline, 8 units at the first control, and 9 units at the last control. Eye with idiopathic macular pucker (EyeiMP) has a flow of 4 units at baseline, 5 units at the first control, and 6 units at the last control. The absolute difference (EyeiMP-Eyefellow) is constant, i.e., it is 3 units for each follow-up timepoints. The relative difference varies from 75% at baseline, 60% at the first control and 50% at the last control. While the absolute difference is an algebraic subtraction between absolute values, the relative difference is a percentage of change in EyeiMP to reference values given by the Eyefellow. b Spectral domain optical coherence tomography (SD-OCT). Left: Automatic segmentation of the internal limiting membrane (ILM) and the retinal pigment epithelium/Bruch’s membrane (RPE/BM) for the measurement of central foveal thickness (CFT), represented on the ETDRS grid. Right: manual segmentation of the outer choroidoscleral boundary for the measurement of choroidal thickness (CT), represented on the ETDRS grid. c En-face OCTA. Foveal avascular zone (FAZ) area of superficial capillary plexus (SCP), automatically calculated by the software Angioscan 8 OCT angiography (OCTA) on a macular 3 × 3 mm map. d B-scan OCTA. Top: Superficial capillary plexus (SCP), generated as a layer extending from the internal limiting membrane (ILM) to a segmentation line located 12 μm above the inner plexiform layer/inner nuclear layer (IPL/INL) interface on a macular 3 × 3 mm map. Bottom: Deep vascular plexus (DVC), generated as a layer extending from 8 μm above the IPL/INL interface to a deeper line 12 μm above the outer plexiform layer/outer nuclear layer (OPL/ONL) on a macular 3 × 3 mm map, including the intermediate (ICP) and the deep capillary plexuses (DCP). e En-face OCTA image of the choriocapillary (CC) layer. Isolation of the CC layer by the identification of a slab of 8 μm from 33 μm posteriorly to the segmentation of the retinal pigment epithelium/Bruch’s membrane (RPE/BM) on a macular 3 × 3 mm map. f OCTA image after elaboration with FIJI software (imageJ version 1.52e extension, National Institutes of Health, Bethesda, Maryland, USA): automatic local thresholding analysis performed with the Phansalkar method using a radius of 15 pixels available in the aforementioned version of the software, according to Spaide’s method [21, 22]. Automatic distribution of the obtained data into 15 categories in a range from 1 to 100 pixels, distributed on a logarithm graph number of areas vs. logarithm amplitude of areas of flow voids (FV). The resulting scatter chart can be intersected by a trend line described by the mathematical relationship described by Spaide: log (number of areas) = m log (amplitude of areas) + b. The slope of regression line is represented by the absolute angular coefficient “m” value, that increases for larger choriocapillary (CC) streams.
Fig. 2
Fig. 2. Thickness variation.
a Variation of central foveal thickness (CFT) in eyes with idiopathic macular pucker (EyeiMP) and in healthy fellow eyes (Eyefellow) from baseline to each time points of the follow-up. b Variation of choroidal thickness (CT) in eyes with idiopathic macular pucker (EyeiMP) and in healthy fellow eyes (Eyefellow) during the follow-up, absolute and relative difference. c Variation of foveal avascular zone area (FAZ area) in eyes with idiopathic macular pucker (EyeiMP) and in healthy fellow eyes (Eyefellow) during the follow-up. d Variation of choriocapillaris (CC) flow in eyes with idiopathic macular pucker (EyeiMP) and in healthy fellow eyes (Eyefellow) during the follow-up, absolute and relative difference.
Fig. 3
Fig. 3. Vascular flow of superficial capillary plexus.
Variation of superficial capillary plexus (SCP) indices: vessel area density (VAD), vessel length fraction (VLF), vessel diameter index (VDI) in eyes with idiopathic macular pucker (EyeiMP) and in healthy fellow eyes (Eyefellow) during the follow-up, absolute and relative difference.
Fig. 4
Fig. 4. Vascular flow of deep vascular complex.
Variation of deep vascular complex (DVC) indices: vessel area density (VAD), vessel length fraction (VLF), vessel diameter index (VDI) in eyes with idiopathic macular pucker (EyeiMP) and in healthy fellow eyes (Eyefellow) during the follow-up, absolute and relative difference.
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Comment on

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