Evaluation of the posterior segment vascular structures of Behcet's patients with and without ocular involvement

Purpose: It is aimed to analyze the retinal vessel diameter measurements obtained from color digital fundus photographs with the help of IVAN software between 3 groups as follows: Behcet's patients with ocular involvement of which are in remission, Behcet's patients without ocular involvement, control group. In addition, it is aimed to examine the differences in the thickness of the macula, choroid and other retinal layers in all patient groups and control groups by performing SD-OCT (Spectral Domain Optical Coherence Tomography), EDI-OCT (Enhanced depth imaging-OCT) OCT segmentation analysis. Materials and methods: Forty-four eyes of 44 patients with Behcet's disease with ocular involvement without active uveitis, 40 eyes of the 40 patients with Behcet's disease without ocular involvement and 60 eyes of 60 healthy volunteers whose examination revealed with normal ophthalmological examination, whom applied to Adiyaman University Faculty of Medicine, Department of Ophthalmology, between 17 February 2021 and 15 September 2021 were included in the study. After detailed ophthalmological examinations of all patients, retinal layers and central macular thickness (CMT) were evaluated with OCT. Color fundus images of all patients were taken with a fundus camera system. SPSS V23 program was used in statistical analysis. Significance level was taken as p<0.05. Results: Retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), photoreceptor layer (PRL) thicknesses were found to be significantly thinner in the ocular Behcet group compared to the control group. There was no significant difference between the groups in terms of outer plexiform layer (OPL), outer nuclear layer (ONL), retinal pigment epithelium (RPE) thicknesses. There was a significant difference between the Ocular Behcet group and the control group in terms of CMT. CMT was significantly thinner in the ocular Behcet group compared to the control group. When the choroidal thicknesses were compared between the groups, no significant difference was found in the sub foveal choroidal thickness, the choroidal thickness measured from 1500 µm nasal of the fovea, and the choroidal thickness measured from 1500 µm temporally of the fovea. As a result of the analysis of retinal vessel diameters between the groups, Central retinal artery equivalent (CRAE) was found to be the lowest in the ocular Behcet group and the highest in the control group. Central retinal vein equivalent (CRVE) was found to be highest in the ocular Behcet group and lowest in the control group. A significant difference was found between the Ocular Behcet group and the non-ocular Behcet group, between the ocular Behcet group and the control group, and between the non-ocular Behcet group and the control group in all posthoc analyzes in terms of CRAE and CRVE. Conclusion: Measuring individual layers of the retina with OCT can enable us to follow neurodegeneration and subclinical inflammatory activity in Behçet's patients, even if there is no clinical ocular involvement. Retinal photography allows for more objective documentation of retinal vessels. For this reason, we thought that analyzes with digital fundus photography have the potential to have an important place in the follow-up of ocular inflammation and vasculitis in a chronic inflammatory disease such as Behçet's disease, in the early diagnosis of ocular involvement and in the evaluation of response to treatment. In order to evaluate the accuracy and general validity of the data we obtained; it should be repeated in much larger patient series. Keywords: Behçet's Disease, Optical Coherence Tomography, Digital Fundus Photography