ROC curve analysis is often applied to measure the diagnostic accuracy of a biomarker. The analysis results in two gains: diagnostic accuracy of the biomarker and the optimal cut-point value. There are many methods proposed in the literature to obtain the optimal cut-point value. In this study, a new approach, alternative to these methods, is proposed. The proposed approach is based on the value of the area under the ROC curve. This method defines the optimal cut-point value as the value whose sensitivity and specificity are the closest to the value of the area under the ROC curve and the absolute value of the difference between the sensitivity and specificity values is minimum. This approach is very practical. In this study, the results of the proposed method are compared with those of the standard approaches, by using simulated data with different distribution and homogeneity conditions as well as a real data. According to the simulation results, the use of the proposed method is advised for finding the true cut-point.

Objective: To evaluate the choroidal thickness in patients with multiple sclerosis (MS) using enhanced depth imaging optical coherence tomography (EDI-OCT). Methods: In this observational comparative study, 68 eyes of 34 MS patients and 60 eyes of 30 healthy subjects were evaluated. All participants underwent complete ophthalmologic examination and OCT scanning. Choroidal thickness measurements were performed at seven points. Results: The mean subfoveal choroidal thickness was reduced significantly in MS patients (310.71 ± 61.85 μm) versus healthy controls (364.85 ± 41.81 μm) (p < 0.001). The difference was also significant at all six measurement points (p < 0.001 for all). Choroidal thickness measurements revealed no significant difference between MS eyes with a prior optic neuritis (ON) history (MS ON) and those without ON history (MS non-ON). Subfoveal choroidal thickness did not correlate with retinal nerve fiber layer and Expanded Disability Status Scale score, but reduced choroidal thickness was associated with longer disease duration (r = -0.28, p = 0.019) in MS patients. Conclusion: In MS patients, choroidal structural changes occur both in MS ON and MS non-ON eyes. The decreased choroidal thickness might provide evidence to support a potential role of vascular dysregulation in the pathophysiology of MS.

Purpose: To evaluate choroidal thickness (CT) and investigate the involvement of choroidal circulation in patients with systemic sclerosis (SSc). Methods: A total of 120 eyes of 60 SSc patients and 60 eyes of 30 healthy controls were evaluated. CT measurements were performed at the subfoveal region, 1000 µm nasal and 1000 µm temporal to the fovea, using enhanced depth imaging optical coherence tomography. CT measurements were compared between the patients and controls. Results: The average subfoveal, parafoveal nasal and parafoveal temporal CT were significantly thinner in SSc patients when compared with healthy controls (297.77 ± 60.8 µm vs 339.8 ± 50.4 µm; 267.32 ± 51.1 µm vs 308.65 ± 49.9 µm; 270.63 ± 46.3 µm vs 309.22 ± 42.4 µm, respectively; p<0.001 for all). Conclusions: Reduced CT in SSc patients supports the hypothesis of widespread vascular injury, including the ocular microcirculation.