Background: This study aimed to investigate whether the choroidal vascularity index (CVI), choroidal thickness (ChT), and retinal nerve fiber thickness (RNFL) of patients with allergic asthma change compared to the healthy control group. Methods: This cross-sectional, observational study comprised 59 eyes of 59 patients with allergic asthma (Group 1) and 50 eyes of 50 age and sex-matched healthy volunteers as a control group (Group 2). CVI was measured by binarization of images obtained from choroidal enhanced depth imaging (EDI) mode optic coherence tomography. CVI was defined as the ratio of the choroidal luminal area to the total circumscribed choroidal area. ChT was measured manually at 3 points, subfoveal and 1000 microns nasal and temporal to the fovea (SFCT, N1000, and T1000 respectively). RNFL measurements were subdivided as global, nasal, temporal, superonasal, superotemporal, inferonasal, and inferotemporal quadrants. Results: Subfoveal CVI and ChT were significantly lower in asthma patients (p:0,043 and p: 0.034, respectively). N1000 and T1000 ChT and RNFL thicknesses were lower in asthma patients compared to the control group, though no significant difference was found between them (p> 0.05). Conclusion: Our findings suggest that asthma patients have choroidal structural changes. In the literature, there are not enough studies regarding the effects of asthma on ocular parameters.