Background: The objective of this study is to assess the subfoveal choroidal thickness (SFCT) in individuals with macular edema (ME) resulting from retinal vein occlusion (RVO). Additionally, the study aims to examine the immediate effects following a solitary intravitreal ranibizumab (IVR) injection. Furthermore, it is important to compare the changes in subfoveal choroidal thickness (SFCT) between central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO). Methods: This study involved a prospective longitudinal examination of 100 eyes belonging to 100 patients who had not received any prior treatment for retinal vein occlusion. Among these patients, 24 had central retinal vein occlusion (CRVO) and 40 had branch retinal vein occlusion (BRVO). In this study, Spectral-domain optical coherence tomography (SD-OCT) was employed to assess various ocular parameters including peripapillary choroidal thickness (PPCT), subfoveal choroidal thickness (SFCT), peripapillary retinal nerve fiber layer (pRNFL) thickness, and central macular thickness (CMT) in both affected and fellow eyes. Measurements were taken at baseline during the acute phase, as well as at 3 and 9 months following anti-VEGF treatment. The Spectralis HRA-OCT system from Heidelberg was utilized for this purpose. A p-value less than or equal to 0.05 was deemed to be statistically significant. Results: When compared to other eyes in CRVO and BRVO, affected eyes had thicker baseline PPCT and SFCT (p 0.05). At three months following baseline, PPCT in the affected eyes significantly decreased in both groups (p 0.05). PPCT remained stable at 9 months as compared to 3 months (p > 0.05). At 3 months, both groups' affected eyes' SFCT significantly decreased (p 0.05). SFCT decreased in the CRVO patients at 9 months compared to 3 months (p = 0.047), but it remained stable in the BRVO patients (p = 0.850). At any timepoint in both groups, there were no correlations between SFCT and CMT (p > 0.05). At 3 months, there is a correlation between PPCT and pRNFL in CRVO, but no other correlations were discovered during the follow-up. In BRVO, there was no discernible correlation between PPCT and pRNFL. Conclusion: Both in CRVO and BRVO eyes, PPCT and SFCT at diagnosis are significantly thicker compared to the fellow eye, suggesting a possible increase in CT immediately after the occlusion, which is followed by a decrease at an early follow-up stage.