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Background: The vast majority of oxygen required for outer retinal layer, including photoreceptors is provided by choriocapillaris with a little support of deep retinal capillaris. This organization may differ between individuals depending on the variability in photoreceptor density. Based on these, we evaluated the changes and interaction between the retinal capillary networks—organization of retinal microvessels—using optical coherence tomography angiography (OCTA) considering ocular perfusion pressure (OPP) and diurnal variations. Methods: Forty eyes of 40 healthy volunteers formed the sample for this cross-sectional study. Mean arterial pressure (mAP), OPP, and OCTA measures were noted at two different time points on a single day. Results: The mAP, OPP, superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) perfusion values showed no diurnal change (p>0.05). When compared the mAP and OPP with the SCP, DCP, and CC perfusion measurements, there was no significant relation between them (p>0.05). There was a significant moderate positive correlation between DCP and CC values in both morning and afternoon (r=0.422; p=0.007, r=0.493; p=0.001, respectively). Conclusion: The DCP and CC perfusion values show a significant moderate positive correlation. This correlation may suggest the role of DCP in the maintenance of oxygen homeostasis in outer retinal layers.

Background Reflectance spectroscopy, which is one of spectroscopic techniques, is an optical technique and has the potential to differentiate cancerous tissues from normal tissues. There are several studies which evaluate the diagnostic accuracy of this method in the literature. Objective The aim of this study is to assess the sensitivity and specificity of the fiber optic reflectance spectroscopy system in diagnosis of cancerous tissue via meta-analysis. Materials and methods In this meta-analysis paper, the literature search was conducted using the “PubMed” database as of 16-August-2018 last date. A total of 30 articles which the pathological evaluation was accepted as the gold standard were included in the meta-analysis, excluding the articles that were out of context and did not contain the required statistics. Results Overall sensitivity was 0.82; overall specificity was 0.84 and area under the summary receiver operating characteristic curve was 0.89 in differentiating cancerous from normal tissue by using fiber optic reflectance spectroscopy system. Overall diagnostic odds ratio was obtained as 29.42. Conclusion In this study, according to the results of meta-analysis conducted to evaluate the diagnostic accuracy of the fiber optic reflectance spectroscopy high overall sensitivity and specificity values were obtained in the detection of cancerous tissue.

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