Does corneal epithelial thickness show the severity of psoriasis? SD-OCT study

Background: Previous studies have generally focused on dry eye test abnormalities and ocular involvements such as uveitis, and blepharitis in psoriasis. Psoriasis area severity ındex (PASI), which is used to assess psoriasis severity, is a time-consuming and complex tool. Objective: To evaluate the relationship between disease severity and central corneal epithelial thickness (CCET) in psoriasis. Methods: 175 eyes of 175 psoriasis patients and 57 eyes of 57 healthy individuals as a control group was included in this study. Psoriasis patients were divided into three subgroups according to PASI score as < 10 mild, 10‒20 moderate and > 20 severe. CCET was measured by spectral domain-optical coherence tomography (SD-OCT), and mean values were recorded. Mean CCET values were compared between the psoriasis groups and the control group. Additionally, the relationship between PASI score and CCET was examined. Results: The mean CCET value was 58.06 ± 3.1 μm in the mild group, 60.10 ± 5.0 μm in the moderate group, 65.75 ± 6.3 μm in the severe group and 56.16 ± 3.1 μm in the control group. It was determined that the mean CCET value was significantly higher in all psoriasis groups compared to the control group (p < 0.001). The mean CCET value was significantly higher in the moderate psoriasis group than in the mild psoriasis group (p = 0.018), and in the severe psoriasis group compared to the moderate psoriasis group (p < 0.001). There was a strong positive correlation between PASI score and CCET (p < 0.001, r = 0.519). Study limitations: Cross-sectional design and a relatively small number of participants. Conclusions: There is a strong positive correlation between psoriasis severity and CCET. Contactless measurement of CCET by SD-OCT can be an indicator of psoriasis severity.