Purpose: To report two cases of typical multiple evanescent white dot syndrome (MEWDS), in which Swept‑ Source Optical Coherence Tomography angiography (SS‑ OCTA) revealed transient areas of flow deficit at the level of the choriocapillaris. Methods: The SS‑ OCTA images of two female patients with typical MEWDS were analyzed at the onset of the disease and during follow‑ up. Results: The patients were aged 24 and 25 years, respectively. Previous medical history was unremarkable in both cases. The diagnosis of MEWDS was made on the basis of typical clinical findings and results of fundus autofluorescence, fluorescein angiography, and Optical Coherence Tomography. At presentation, SS‑ OCTA showed a few small hypointense areas of flow deficit at the level of the choriocapillaris in both cases. During follow‑ up, SS‑ OCTA showed complete resolution of choriocapillaris flow voids. Conclusion: Both our patients with typical acute MEWDS showed SS‑ OCTA multifocal small areas of flow reduction at the level of the choriocapillaris, with full recovery during the follow‑ up. This finding supports the hypothesis of transient, primary, or secondary choriocapillaris hypoperfusion in typical MEWDS.

Background and Objective: One of the most common extracutaneous complications in psoriasis patients is ocular complications, which is controversial concerning its effect on choroidal thickness. This study aimed to compare the psoriasis patients with healthy individuals in terms of the thickness of the choroidal layer using the Optical Coherence Tomography technique. Materials and Methods: In this case-control study, 30 psoriasis patients were compared with 32 healthy individuals who were matched for gender and age. Choroidal thickness was measured in both groups using the Optical Coherence Tomography technique. Furthermore, the relationship of the choroidal thickness with the severity and duration of the disease was assessed in patients. Results: The mean choroidal thickness of the left eye (312. 1± 12. 0 mμ vs. 296. 3± 20. 8 mμ ), right eye (310. 6± 12. 5mμ vs. 297. 5± 17. 5mμ ), and regardless of the left or right eye (311. 3± 12. 2 mμ vs. 296. 9± 19. 1mμ ) was significantly higher in patients, compared to the control group (P=0. 001 for all three mean values). No significant relationship was found between disease duration and severity with choroid thickness. Moreover, the patients with multiple limb involvement had a higher mean choroid thickness; however, it was not statistically significant. Conclusion: According to the results of the present study, patients with psoriasis have a greater choroidal thickness, compared to healthy individuals, which is not related to the severity, type of involvement, and duration of the disease.

Background: The symmetricity of even organs of body may help clinicians in the early detection of diseases.So, we estimated the cup-to-disk ratio (CDR) in left and right eyes and checked the symmetricity between the two eyes using the data of Optical Coherence Tomography (OCT).Methods: In this study, data from 40 normal subjects were used. This data was taken from the 3D-OCT1000 Tapcon model. For estimating CDR in each B-scan, at first the internal limiting membrane (ILM) and retinal pigment epithelium (RPE) layers were extracted; then using the end-point of RPE layer and the depth of cup, the boundary of disk and cup were determined. Finally, CDR of each B-scan was compared point-by-point and the symmetricity parameters were evaluated.Findings: CDRs in the left and right eyes of 40 normal data were investigated locally. We divided optic disk area into three regions named upper, middle and lower. Then, CDR of each region was calculated for left and right eyes of each patient. The local CDR were 0.433±0.0548, 0.432±0.061, and 0.432±0.0635 for the right eyes and 0.441±0.0635, 0.443±0.0731, and 0.417 ± 0.675 for the left eyes in upper, middle and lower regions, respectively. The differences between local CDRs in different regions of the two eyes were 0.0483±0.042, 0.0420±0.039, and 0.067±0.045, respectively.Conclusion: The results of local comparison of CDRs between the left and right eyes indicated that the level of asymmetricity in the lower region of disk was higher than upper and middle regions, and the middle region has the most symmetricity. In addition, in point-by-point symmetricity evaluation of CDRs, the highest level of symmetricity is seen in the second B-scan, near the center of optic disk.

We performed a comprehensive search of the published literature in PubMed and Google Scholar to identify types, prevalence, etiology, clinical impact, and current methods for correction of various artifacts in Optical Coherence Tomography angiography (OCTA) images. We found that the prevalence of OCTA image artifacts is fairly high. Artifacts associated with eye motion, misidentification of retinal layers, projections, and low Optical Coherence Tomography signal are the most prevalent types. Artifacts in OCTA images are the major limitations of this diagnostic modality in clinical practice and identification of these artifacts and measures to mitigate them are essential for correct diagnosis and follow-up of patients.

Purpose: To identify and explain different artifacts in macular Optical Coherence Tomography (OCT). Methods: For this comprehensive review, a PubMed and Google Scholar (January 1995– October 2018) search was conducted by the researchers, using the keywords such as OCT, artifacts, artefact, and macula. Results: We reviewed the main OCT artifacts including software break-down or misidentification of retinal layers, incomplete segmentation error, complete segmentation failure, mirror artifact (inverted artifact), cut edge artifact, degraded image scan, out‑ of‑ register artifact, off‑ center artifact, motion artifact, foveal duplication, segmentation shift, blink artifact, static or fixed image artifact, linear artifact, and perfluorocarbon liquid‑ producing artifact. Conclusions: There are various artifacts in OCT image scans. The identification of these artifacts may help in accurate interpretations of OCT images in clinical settings that can affect the diagnosis and management of different retinal disorders.

Optical Coherence Tomography Angiography (OCTA) is a new imaging technique that allows imaging of the retina and optic nerve. It is noninvasive and provides high resolution and rapid image. It is reproducible and has several applications in evaluation of retinal and optic nerve diseases. In this review, principle of imaging technique and application of OCTA in glaucoma detection will be discussed.

Background: Retina is the innermost tissue in human eye which sends visual information to the brain by means of optic nerve. Designing an intra-retinal layer segmentation method which can detect the retina surfaces properly in the presence of noise and lack of contrast is an important step in ophthalmology. In this study the combination of morphological component analysis (MCA) and dynamic programming (DP) is used automatically for segmentation of Optical Coherence Tomography (OCT) images.Methods: Data set for this study was 55 samples which were taken from normal people by Topcon OCT-1000.This study had two phases. In MCA phase the image dictionary was created by clustering with eigenvalues (k-SVD), and then the image was decomposed to cartoon and texture parts by selecting proper bases. In the second phase segmentation was done by the dynamic programming (DP) method on cartoon part and the retinal pigment epithelium (RPE), Verhoeff's memberane (VM), outer segment layer (OSL), innercollagenous layer (ICL), inner synaptic layer (ISL), and outer limiting membrane (OLM) layers were detected.Findings: Comparing the obtained results with gold standard (manual segmentation) shows that minimum error belongs to OSL surface and its error in the form of mean±SD (standard derivation) is 0.030±0.167. For other surfaces the error is calculated in this way from left to right for RPE, VM, ICL, ISL, OLM: -0.66±0.33, -0.59±0.31, -1.00±0.49, -1.72±0.61, -1.05±0.51.Conclusion: MCA in combination with DP can work as an automatic method for six lower intra retina layers' segmentation with acceptable accuracy. One of the main advantages of this method is omitting preprocessing phase for segmentation.

Introduction: To evaluate the clera canal diameters at optic nerve head in patients with nonarteritic anterior ischemic optic neuropathy (NAION) using Optical Coherence Tomography (OCT) and compare the results with fellow eyes and control group.Material and Methods: In a prospective study, optic nerve head OCT was performed in acute phase of NAION.Horizontal and vertical diameters of the scleral canal at optic disc i.e. the termination of the retinal pigment epithelium, were recorded. The data was compared with fellow eyes and an age- and sex-matched normal control group.Results: Thirty eyes of 30 patients and 20 eyes of 20 normal subjects were studied. Scleral canal diameters were the same for normal fellow eyes, optic atrophy fellow eyes and control eyes. Scleral canal diameters of NAION eyes were significantly greater than control and normal fellow eyes (P<0.001), however, the difference was not significant for optic atrophy fellow eyes.Conclusion: Although in the acute phase, the scleral canal diameters were greater in NAION eyes, no significant difference was found between normal fellow eyes and control eyes.