Response: comment on 'Swept-source optical coherence tomography angiography reveals vascular changes in intermediate uveitis': Letter to the Editor.

Abstract

Editor, We wish to thank Prof. Robert P. Finger and Dr. Wintergerst Maximilian (Wintergerst & Finger, 2019) for their comments on our article ‘Swept-source optical coherence tomography angiography reveals vascular changes in intermediate uveitis’. (Tian et al. 2019) The results of our study using anova demonstrate that patients with intermediate uveitis and concomitant vasculitis and patients with intermediate uveitis had reduced central vessel density compared to healthy age-matched controls, which is in line with the findings of Wintergerst et al. (2018). Using a multivariable analysis, however, the presence of a cystoid macular edema (CME) turned out to has more impact on vessel density than the disease entity itself in our patient cohort. Despite this fact, CME only explained about 10% of the changes in our patient cohort. (Tian et al. 2019). Ergo, more, so far unknown contributing factors must be present, which lead to reduced vessel parameters. Reduced central retinal thickness (CRT) was found to be one of these factors. (Wintergerst et al. 2018). Based on their suggestion and findings, we assessed CRT as potential factor in our study cohort. There was no association between CRT and vessel density in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), respectively (R2 = 0.03, p = 0.09 and R2 = 0.03, p = 0.2). However, as disorganization of retinal inner layers (DRIL) has been described as prognostic factor not only in DME but also in uveitic CME (Grewal et al. 2017) we also assessed the potential impact of DRIL in our patient cohort. And, indeed the presence of DRIL had a significant effect on the vessel density of the SCP (R2 = 0.08, p = 0.006), while the DCP (R2 = 0.01, p = 0.26) was not affected. Like CME though, DRIL explained only 8% of the changes. Thus, there are still a lot of unknown factors, which contribute to reduced vessel parameters in uveitic eyes. One of them may be the presence of media opacities caused by, for example cataract and/or inflammation, which was so far not considered in the assessment of retinal blood flow measurements of uveitic eyes and was found to significantly influence quantitative vessel parameters (Yu et al. 2018). Best Regards, Marion R. Munk