Changes in choroidal morphology and blood perfusion in patients with macular edema secondary to retinal vein occlusion after intravitreal injections of ranibizumab

Objective  To observe the changes in choroidal morphology and blood perfusion in patients with macular edema secondary to retinal vein occlusion (RVO) after intravitreal injections of ranibizumab.

Methods  A cohort study was performed.A total of 157 patients (157 eyes) with macular edema secondary to monocular acute retinal vein occlusion (RVO) were enrolled in the Third People’s Hospital of Dalian from January 2022 to March 2023.There were 66 cases (66 eyes) with central retinal vein occlusion (CRVO) and 91 cases (91 eyes) with branch retinal vein occlusion (BRVO).All patients were treated with 3+ pro re nata (PRN) regimen of ranibizumab.Before and 1 month after each injection, the central retinal thickness of the macula was measured by optical coherence tomography (OCT).Clear images of the choroid were obtained using the OCT enhanced depth scan mode.Subfoveal choroidal thickness (SFCT), the nasal choroidal thickness at 1 500 μm of macula (CT N1.5 mm), the temporal choroidal thickness at 1 500 μm of macula (CT T1.5 mm) were measured and mean macular thickness (CT Mean) was calculated.Binarization of choroidal images processed by ImageJ software was used to analyze luminal area (LA), stromal area (SA) and total choroidal area (TCA), and choroidal vascularity index (CVI) was calculated.This study adhered to the Declaration of Helsinki and was approved by the Ethics Committee of the Third People’s Hospital of Dalian (No.2023-145-001).

Results  SFCT, CT T1.5 mm, CT N1.5 mm, CT Mean, LA, SA, TCA and CVI of RVO eyes were higher than those of the contralateral eyes and the differences were statistically significant (all P<0.01).CT Mean in CRVO group was (326.99±64.92)μm, which was higher than (299.80±73.08)μm in BRVO group, with a statistically significant difference ( t=2.41, P=0.02).Baseline CVI values in CRVO group and BRVO group were (72.50±5.62)% and (72.33±5.85)%, respectively, with no significant difference ( t=0.187, P=0.85).In eyes with RVO, CRVO and BRVO, SFCT, CT T1.5 mm, CT N1.5 mm, CT Mean, LA, SA, TCA and CVI after every injection were lower than the baseline and the differences were statistically significant (all P<0.05).In eyes with CRVO, there was no significant difference in LA and CVI between first and second injections (both P>0.05), and SFCT, CT T1.5 mm, CT N1.5 mm, CT Mean, SA and TCA after second injection were lower than those after first injection with statistically significant differences (all P<0.05).In eyes with BRVO, there was no significant difference in SA and CVI between first and second injections (both P>0.05), and SFCT, CT T1.5 mm, CT N1.5 mm, CT Mean, LA and TCA after second injection were lower than those after first injection with statistically significant differences (all P<0.05).In eyes with RVO, CRVO and BRVO, there was no significant difference in SFCT, CT T1.5 mm, CT N1.5 mm, CT Mean, SA, TCA and CVI between second and third injections (all P>0.05).

Conclusions  After intravitreal injection of ranibizumab, the choroidal thickness becomes thinner and CVI decreases in eyes with macular edema secondary to RVO, and remain relatively stable after the second injection.

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