Clinical predictive factors and imaging biomarkers of treatment response to half dose PDT in patients with chronic central serous chorioretinopathy.

PURPOSE: To determine the clinical and imaging biomarkers of the response to half-dose photodynamic therapy (HD-PDT) in patients with central serous chorioretinopathy (CSC) METHODS: Clinical records and baseline ophthalmic images of 67 chronic CSC patients who underwent HD-PDT were assessed. In addition to demographic data, optical coherence tomography (OCT), fluorescein angiography (FA) and fundus autofluorescence (FAF) images were analyzed for specific biomarkers. The patients were categorized to early responder and late responder based on the time needed for complete resolution of subretinal fluid after PDT (less than 1 month vs. more than 1 month). The baseline clinical and imaging biomarkers were compared between the two groups. RESULTS: Seventy-three eyes of 67 patients were included in the study. The mean response time to PDT was 1.63 ± 1.48 months with 82.2% (60/73) of eyes categorized as early responder. The mean response time to PDT in delayed-response group was 4.15±1.51 months. In multivariate analysis, delayed response to PDT was associated with lacking history of systemic corticosteroid consumption, lacking history of pretreatment with eplerenone or acetazolamide before PDT and presence of hyperreflective foci in baseline OCT images (all p values < 0.05). There was no association between final visual outcome and late response to PDT. CONCLUSION: The presence of inflammatory biomarkers such as hyperreflective foci in baseline OCT images might be indicative of resistance to PDT. Moreover, the effect of pretreatment with mineralocorticoid antagonist on the response to PDT in chronic CSC should be explored in future prospective studies.

Genetic insights into PHARC syndrome: identification of a novel frameshift mutation in ABHD12.

BACKGROUND: Mutations in ABHD12 (OMIM: 613,599) are associated with polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataract (PHARC) syndrome (OMIM: 612674), which is a rare autosomal recessive neurodegenerative disease. PHARC syndrome is easily misdiagnosed as other neurologic disorders, such as retinitis pigmentosa, Charcot-Marie-Tooth disease, and Refsum disease, due to phenotype variability and slow progression. This paper presents a novel mutation in ABHD12 in two affected siblings with PHARC syndrome phenotypes. In addition, we summarize genotype-phenotype information of the previously reported patients with ABHD12 mutation. METHODS: Following a thorough medical evaluation, whole-exome sequencing was done on the proband to look for potential genetic causes. This was followed by confirmation of identified variant in the proband and segregation analysis in the family by Sanger sequencing. The variants were interpreted based on the American College of Medical Genetics and Genomics (ACMG) guidelines. RESULTS: A novel pathogenic homozygous frameshift variant, NM_001042472.3:c.601dup, p.(Val201GlyfsTer4), was identified in exon 6 of ABHD12 (ACMG criteria: PVS1 and PM2, PM1, PM4, PP3, and PP4). Through Sanger sequencing, we showed that this variant is co-segregated with the disease in the family. Further medical evaluations confirmed the compatibility of the patients' phenotype with PHARC syndrome. CONCLUSIONS: Our findings expand the spectrum of mutations in the ABHD12 and emphasize the significance of multidisciplinary diagnostic collaboration among clinicians and geneticists to solve the differential diagnosis of related disorders. Moreover, a summary based on mutations found so far in the ABHD12 gene did not suggest a clear genotype-phenotype correlation for PHARC syndrome.

Unplanned Reoperation following Vitreoretinal Surgery.

Purpose: To evaluate the incidence of unplanned return to the operating room following vitreoretinal surgery and assess the reasons. Methods: In this retrospective case series, medical records of all patients who underwent vitreoretinal surgery were reviewed to determine the incidence and reasons of early (<30 days postoperatively) and late (≥30 days postoperatively) unplanned reoperations after the surgery. Results: A total of 488 eyes of 468 patients with a mean age of 55.84 ± 18.23 years were included. Fourteen percent (68/488) of eyes required one or more unplanned reoperation following their primary surgery. These include 3.9% (19/488) for the early and 10.0% (49/488) for the late reoperation. The most common primary reason for baseline surgery was rhegmatogenous retinal detachment (RRD) without proliferative vitreoretinopathy (PVR, 38.2%), followed by RD with PVR (23.5%), and tractional RD (TRD, 19.1%). Unplanned reoperations were most common in RD with PVR (19.3%), RRD without PVR (17.2%), and TRD (14.4%). Overall, the most common reasons of the first unplanned reoperation were repeated RD with PVR (27.9%), repeated RD (19.1%), and the presence of silicone oil (SO) in the anterior chamber (AC) (10.3%). For early unplanned reoperations, SO in AC, postoperative endophthalmitis, and persistent hyphema were the most common causes. Repeated RD with PVR was the most prevalent cause of late unplanned reoperations (34.7%). In the multivariate analysis, preoperative best-corrected visual acuity (BCVA) was significantly lower in eyes with unplanned reoperation than in eyes without (P = 0.011). Conclusions: Unplanned reoperation following vitreoretinal surgery is not very common, and occurs mostly in the setting of PVR, RRD, and TRD. Lower preoperative BCVA may indicate an increased chance of future unplanned reoperation(s).

Ocular safety of intravitreal ethylene diamine tetra acetic acid (EDTA): An experimental feasibility study.

Ethylene diamine tetra acetic acid (EDTA) is a chelating component that is able to diminish oxidative reactivity and can be a potential neuroprotective drug in various ocular diseases. For assessing the safety of intravitreal EDTA, 10 rabbits were allocated and divided into 5 groups. Right eyes of the animals received intravitreal EDTA (112.5, 225, 450, 900 and 1800 µg /0.1 ml). Fellow eyes were considered as controls. Clinical examinations and electroretinography (ERG) were performed at the baseline and on day 28. The enucleated eyes were subjected to hematoxylin and eosin (H&E) staining, immunohistochemistry for glial fibrillary acidic protein (GFAP) and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test. Clinical examinations, H&E staining and TUNEL assay were unremarkable. The ERG test did not exhibit any significant alteration compared to the baseline values, except for a significant decrease in just one measurement of the eyes injected with 225 µg EDTA. The mean scores of GFAP immune reactivity in the eyes injected with 112.5 and 225 µg EDTA indicated a non-significant reaction. The scores in higher doses were significant. We suggest intravitreal EDTA with a dose threshold of < 450 µg should be studied for ratification of the safe dose.

Baseline retinal vascular bed area on ultra-wide field fluorescein angiography correlates with the anatomical outcome of diabetic macular oedema to ranibizumab therapy: two-year analysis of the DAVE Study.

PURPOSE: To determine the relationship between baseline retinal non-perfusion area (NPA) and retinal vascular bed area (RVBA) on ultra-wide field fluorescein angiography (UWF FA) and long-term response to intravitreal ranibizumab therapy in diabetic macular oedema (DMO). METHODS: A post-hoc, 2-year observational case series. Baseline UWF FA images (Optos 200Tx) of 40 eyes from 29 patients with diabetes mellitus and treatment naïve DMO in the DAVE (NCT01552408) study were montaged and stereographically projected at the Doheny Image Reading Center to adjust for peripheral distortion. The retinal vasculature was automatically extracted to calculate RVBA. NPA was manually delineated by two masked certified graders. RVBA and NPA were computed in mm2 automatically by adjusting for peripheral distortion and then correlated with the severity of DMO. RESULTS: While global NPA at baseline was not correlated to retinal thickness measurements, baseline NPA in the superior retina was associated with the macular volume (MV) improvement (P = 0.022). Multivariate analysis revealed a smaller RVBA at baseline was correlated with a better MV outcome at two-year follow-up after adjusting for confounding factors (P = 0.049). CONCLUSION: Eyes with smaller baseline RVBA appear to have a better long-term anatomic outcome of DMO.

Accuracy of peripapillary OCTA in patients with acute nonarteritic anterior ischemic optic neuropathy.

OBJECTIVE: To evaluate the accuracy of peripapillary optical coherence tomography angiography (OCTA) segmentation in eyes with acute nonarteritic anterior ischemic optic neuropathy (NAION) and healthy eyes. METHOD: In this retrospective study, en face OCTA images of the optic disc of healthy eyes and eyes with unilateral acute NAION were obtained. The disc boundary and radial peripapillary capillary (RPC) segmentation were generated automatically by the instrument software and then corrected by 2 expert investigators. The frequency of segmentation errors and its impact on vessel density and nerve fibre layer (NFL) thickness measurements were evaluated. RESULTS: Thirty-eight eyes of 38 subjects (18 in the healthy group and 20 in the acute NAION group) were studied. A misidentified disc border was noted in 5 healthy eyes (27.7%) and 19 eyes with NAION (95.0%; p < 0.001). Segmentation error at the RPC level was found in 6 healthy eyes (33.33%) and 19 eyes with NAION (95.0%; p < 0.001). The nerve fibre layer thickness and RPC density did not change statistically significantly after error corrections in both groups. CONCLUSIONS: Misidentification of disc border and segmentation error of the RPC layer are common in OCTA images of the optic disc. Accuracy of OCTA imaging in disc boundary detection and RPC network segmentation is reduced in edematous optic discs following acute NAION.

Delayed-Onset Endophthalmitis after Intravitreal Aflibercept Injection.

Purpose: To describe delayed-onset infectious endophthalmitis 4 months after intravitreal aflibercept injection. Methods: An 80-year-old female was referred with signs and symptoms of clinical endophthalmitis 4 months after intravitreal injection of aflibercept for choroidal neovascularization. Noninfectious causes of panuveitis were excluded and she was diagnosed with delayed-onset postinjection infectious endophthalmitis. Vitreous and aqueous specimens were prepared and antibiotics (vancomycin and ceftazidime) were injected intravitreally. Results: Vitreous culture was positive for Staphylococcus epidermidis. During the 1st month after the antibiotic injections, symptoms and signs of the patient improved and became stable during the 6-month follow-ups. Conclusions: Delayed-onset infectious endophthalmitis can be presented following intravitreal injections. Late presentation of uveitis in postinjected eyes needs complete investigations to rule out infectious endophthalmitis as an ophthalmic emergency.

Differentiating a pachychoroid and healthy choroid using an unsupervised machine learning approach.

The purpose of this study was to introduce a new machine learning approach for differentiation of a pachychoroid from a healthy choroid based on enhanced depth-optical coherence tomography (EDI-OCT) imaging. This study included EDI-OCT images of 103 eyes from 82 patients with central serous chorioretinopathy or pachychoroid pigment epitheliopathy, and 103 eyes from 103 age- and sex-matched healthy subjects. Choroidal features including choroidal thickness (CT), choroidal area (CA), Haller layer thickness (HT), Sattler-choriocapillaris thickness (SCT), and the choroidal vascular index (CVI) were extracted. The Haller ratio (HR) was obtained by dividing HT by CT. Multivariate TwoStep cluster analysis was performed with a preset number of two clusters based on a combination of different choroidal features. Clinical criteria were developed based on the results of the cluster analysis, and two independent skilled retina specialists graded a separate testing dataset based on the new clinical criteria. TwoStep cluster analysis achieved a sensitivity of 1.000 (95-CI: 0.938-1.000) and a specificity of 0.986 (95-CI: 0.919-1.000) in the differentiation of pachy- and healthy choroid. The best result for identification of pachychoroid was obtained for a combination of CT, HR, and CVI, with a correct classification rate of 0.993 (95-CI: 0.980-1.000). Based on the relative variable importance (RVI), the cluster analysis prioritized the choroidal features as follows: HR (RVI: 1.0), CVI (RVI: 0.87), CT (RVI: 0.70), CA (RVI: 0.59), and SCT (RVI: 0.27). After performing a receiver operating characteristic curve analysis on the cluster membership variable, a cutoff point of 389 µm and 0.79 was determined for CT and HR, respectively. Based on these clinical criteria, a sensitivity of 0.793 (95-CI: 0.611-0.904) and a specificity of 0.786 (95-CI: 0.600-0.900) and 0.821 (95-CI: 0.638-0.924) were achieved for each grader. Cohen's kappa of inter-rater reliability was 0.895. Based on an unsupervised machine learning approach, a combination of the Haller ratio and choroidal thickness is the most valuable factor in the differentiation of pachy- and healthy choroids in a clinical setting.

Retinotomy and Retinectomy in the Management of Rhegmatogenous Retinal Detachment Associated with Advanced Proliferative Vitreoretinopathy.

Purpose: To report the anatomical and functional outcomes of retinotomy and/or retinectomy for the management of rhegmatogenous retinal detachment (RRD) complicated by advanced proliferative vitreoretinopathy (PVR). Methods: In this retrospective study, the charts of patients who underwent pars plana vitrectomy with retinotomy and/or retinectomy for the management of RRD complicated by PVR were reviewed. Primary outcome measures were final best-corrected visual acuity (BCVA) and anatomical reattachment rate. Results: Sixty-one eyes of 61 patients with a mean age of 48.56 ± 15.92 were studied. The mean follow-up time was 21.38 ± 23.08 months. The mean angle of the retinotomy was 171.31° ± 79.15°. Thirty-two (52.5%) of them needed extensive (≥180°) retinotomy. In addition, simultaneous retinectomy was performed in 36.2% of the cases. The BCVA was 2.18 ± 0.63 and 1.85 ± 0.71 logMAR before the surgery and at the last visit, respectively (P = 0.001). The initial anatomical success was achieved in 45 eyes (73.8%) after retinotomy surgery. Sixteen eyes (26.2%) had recurrent RD and needed reoperation, which was performed 5.60 ± 4.01 months after the initial retinotomy surgery. At the last examination, the retina was attached in all patients. Conclusion: Retinotomy with/without retinectomy is an effective procedure in the majority of patients with RRD associated with advanced PVR; however, additional surgeries are needed in a significant number of eyes to achieve final anatomical success.

RETINAL VASCULAR BED AREA IN EYES WITH RETINAL VEIN OCCLUSION ON ULTRA-WIDEFIELD FLUORESCEIN ANGIOGRAPHY: WAVE Study.

PURPOSE: To compute retinal vascular bed area (RVBA) in square millimeters on distortion corrected ultra-widefield fluorescein angiography images in eyes with retinal vein occlusion (RVO). METHODS: Prospective observational study. The peripheral distortion of baseline ultra-widefield fluorescein angiography (Optos 200Tx) images of 30 patients with RVO from the WAVE study (NCT01710839) and 13 control eyes of normal subjects was corrected using the stereographic projection method to compute RVBA in square millimeters. RESULTS: In comparison with age- and sex-matched normal control eyes, eyes with RVO had a decreased global RVBA for the entire retina (50.5 ± 20.4 mm 2 vs. 62.6 ± 12.2 mm 2 , P = 0.023). Eyes with RVO and the unaffected fellow eye had a similar RVBA globally (50.5 ± 20.4 mm 2 vs. 46.2 ± 18.9 mm 2 , P = 0.523). The RVBA was observed to negatively correlate with nonperfusion area (R = -0.47, P = 0.009). However, RVBA was not related to the severity of macular edema ( P > 0.05). CONCLUSION: Eyes with RVO have a similar RVBA to the unaffected fellow eyes but with a reduction when compared with normal control eyes. Retinal vascular bed area appears to be a surrogate biomarker of retinal ischemia on ultra-widefield fluorescein angiography but not the extent of macular edema.

Intravitreal recombinant tPA before vitrectomy for diabetic tractional retinal detachment: A randomized controlled trial.

PURPOSE: To investigate the effect of intravitreal recombinant tissue plasminogen activator (rt-PA) injection before vitrectomy on surgical facility and outcome in diabetic tractional retinal detachments (TRD). METHODS: Prospective, randomized, interventional clinical trial. A total of 38 eyes with diabetic TRD were candidates for vitrectomy. Patients were randomized 1:1 to receive intravitreal rt-PA, five to seven days before vitrectomy or no injection. Intraoperative surgical facility and anatomic success at month 3 after surgery were assessed. RESULTS: Mean patient age was 54.2 ± 9.4 years. There was no statistically significant difference between rt-PA and no injection groups with regard to anatomic success (89% versus 95%, respectively, P = 0.547) and best corrected visual acuity at 3 months (2.0 versus 2.1 logMAR, respectively, P = 0.840). However, surgical facility score was statistically significantly lower in rt-PA injection group compared to no injection group (4.1 ± 1.7, 5.8 ± 2.0, respectively, P = 0.007). CONCLUSIONS: Vitrectomy for TRD was easier after preoperative rt-PA injection, without affecting the anatomic and visual outcomes.

Optic Nerve Head Vessel Density Changes from Graves' Disease without TED to TED Dysthyroid Optic Neuropathy: Does Optic Nerve Head Ischemia Play a Role?

PURPOSE: To compare the retinal peripapillary capillary (RPC) vessel density (VD) between 5 groups of patients on the spectrum of thyroid eye disease (TED). METHOD: This is a prospective comparative study looking at 5 groups of patients who were consecutively included from January 2018 to March 2021. They were composed of: Healthy volunteers (39 eyes and 20 subjects), patients with Graves' disease without TED (26 eyes and 13 patients), mild TED (28 eyes and 14 patients), moderate-severe TED (30 eyes and 17 patients), and TED with dysthyroid optic neuropathy (DON) (21 eyes and 12 patients). Ocular and periocular examination, visual field indices, RPC-VD (with optical coherence tomography angiography), and retinal nerve fiber layer, and macular ganglion cell complex thickness were recorded. RESULT: An initial insignificant (0.5 < p < 0.9) rise in the peripapillary-VD (pp-VD) and whole image-VD (wi-VD) from the healthy subject to the Graves' disease without TED was followed by a significant (p = 0.001) fall in RPC-VD in different severity grades of the TED. Paired comparison between the 5 groups showed that the statistically significant fall from the Graves' disease group occurred in the moderate-severe and DON groups (0.001 ≤ p ≤ 0.04). No variable significantly affected the VD (0.08 ≤ p ≤ 0.9). A lower wi-VD and pp-VD were significantly (0.001 ≤ p ≤ 0.009) correlated with the impaired optic nerve functional and structural tests. The sensitivity and specificity of wi-VD (81% and 76%) and pp-VD (69% and 71%) for detecting the DON were statistically significant (p < 0.001). CONCLUSION: Despite an insignificant rise in the wi- and pp-VD from the healthy volunteers to the patients with Graves' disease without TED, VD showed a declining trend in the course of patients with TED, which was statistically significant in the moderate-severe TED and DON groups.

Segmentation Error Correction of the Optical Coherence Tomography Angiography Images in Peer-Reviewed Studies.

Purpose: To assess the percentage of published articles reporting optical coherence tomography angiography (OCTA) metrics regarding the report of segmentation error correction. Methods: A comprehensive search was conducted using the PubMed database for articles on OCTA imaging published between January 1, 2015, and January 1, 2021. All original articles reporting at least one of the OCTA metrics were extracted. The article text was reviewed for the segmentation correction strategy. In addition, the number of articles that mentioned the lack of segmentation error correction as a limitation of the study was recorded. Results: From the initial 5288 articles, 1559 articles were included for detailed review. One hundred ninety-six articles (12.57%) used manual correction for segmentation errors. Of the remaining articles, 589 articles (37.8%) excluded images with significant segmentation errors, and 99 articles (6.3%) mentioned segmentation errors as a limitation of their study. The rest of the articles (675, 43.3%) did not address the segmentation error. Multiple logistic regression analysis revealed that ignorance of segmentation error was significantly associated with lower journal ranks, earlier years of publication and disease category of age-related macular degeneration, and glaucoma (all P < 0.001). Conclusions: A significant proportion of peer-reviewed articles in PubMed, disregarded the segmentation error correction. The conclusions of such studies should be interpreted with caution. Editors, reviewers, and authors of OCTA articles should pay special attention to the correction of segmentation errors.

Differentiating features of OCT angiography in diabetic macular edema.

The purpose of current study was to evaluate different optical coherence tomography angiography (OCTA) metrics in eyes with diabetic retinopathy with and without diabetic macular edema (DME). In this retrospective study, macular OCTA images of eyes with non-proliferative or proliferative diabetic retinopathy were evaluated. Vascular density, vascular complexity and non-perfusion densities were compared between eyes with and without DME. One-hundred-thirty-eight eyes of 92 diabetic patients including 49 eyes with DME were included. In multivariate analysis, the presence of DME was positively associated with geometric perfusion deficit (GPD) in superficial capillary plexus (SCP), capillary non-perfusion (CNP) of SCP, and GPD in deep capillary plexus (DCP) (all P < 0.05). In eyes with DME, central foveal thickness was associated with VD ratio (SCP/DCP) (P = 0.001) and FAZ area (P = 0.001). In conclusion, in eyes with diabetic retinopathy, the presence of DME was associated with more extensive capillary non-perfusion compared to those with no macular edema.

Intravitreal Methotrexate.

Intravitreal methotrexate (MTX) has been proven to be an effective treatment for various intraocular diseases. In this article, a comprehensive review was performed on intravitreal applications of methotrexate. Different aspects of the administration of intravitreal MTX for various clinical conditions such as intraocular tumors, proliferative vitreoretinopathy, diabetic retinopathy, age-related macular degeneration, and uveitis were reviewed and the adverse effects of intravitreal injection of MTX were discussed. The most common indications are intraocular lymphoma and uveitis. Other applications remain challenging and more studies are needed to establish the role of intravitreal MTX in the management of ocular diseases.

Evaluating Reading Performance in Different Preferred Retinal Loci in Persian-Speaking Patients with Age-Related Macular Degeneration.

PURPOSE: To evaluate reading performance in different preferred retinal loci (PRLs) using a Persian version of a Minnesota Low Vision Reading (MNREAD) chart in Persian-speaking patients with age-related macular degeneration (AMD). METHODS: In this cross-sectional study, 35 patients with AMD were assessed. The reading performance was investigated by the MNREAD chart without using low vision aids. The location of PRL was determined monocularly using an MP1 microperimeter (Nidek Technologies, Padua, Italy). The anatomical location of the fovea was determined using optical coherence tomography (OCT). Images were taken with the MP1 microperimeter, and Spectralis HRA-OCT device was processed using graphic software to determine the location of the PRL on the retina. RESULTS: Thirty-five patients (51 eyes) with a mean age of 73.8 ± 7.7 years (range, 54-88 years) were assessed. Mean best corrected distance visual acuity (logMAR) was 0.65 ± 0.35 (range, 0.2-1.3). Mean levels of reading acuity (RA) (P = 0.009) and critical print size (CPS) (P = 0.015) were significantly different in different locations of PRL. Average scores of maximum reading speed (MRS) (P = 0.058) and reading accessibility index (ACC) (P = 0.058) were not statistically significant in different locations of PRL. There was a positive correlation between PRL-fovea distance and RA (P < 0.001, r = 0.591) and CPS (P < 0.001, r = 0.614). Significant negative correlations were observed between PRL-fovea distance and MRS (P < 0.001, r = -0.519) and ACC (P < 0.001, r = -0.545). CONCLUSIONS: This study provides evidence for differences in the reading performance of Persian-speaking patients with AMD in different PRL locations. The average scores of all reading indices obtained in the right-field PRL are lower than those in other areas and are highly correlated with the PRL-fovea distance.

Global burden of paediatric vision impairment: a trend analysis from 1990 to 2017.

OBJECTIVE: To assess the trend of paediatric visual impairment and its disparities by year, sex, age and national socioeconomic levels using disability-adjusted life years (DALYs). METHODS: It is a retrospective analysis of data from the Global Burden of Disease (GBD) 2017. Global and national DALY numbers and rates of vision impairment in three paediatric age groups of 1-4 (preschool children), 5-9 (school children) and 10-14 years (teenagers) years were obtained from the GBD 2017 database. The socioeconomic indices for 195 countries were derived from international open databases. Main outcome measures were comparison of DALYs due to paediatric vision impairment in different age groups by socioeconomic indicators in 2017 and analysis of the trend from 1990. RESULTS: The global prevalence of distance and/or near vision impairment for 1-14 years was 2.8% (95% uncertainty interval (UI): 2.5-3.1) in 2017. The highest DALYs for distance and/or near vision impairment [number=589.93 thousands (95%UI: 367.71-933.29), rate = 92.72 (95%UI: 57.79-146.68)] were observed in teenagers. DALY rate of distance and/or near vision impairment was not associated with socioeconomic indicators, however, DALY rate of refractive disorders had positive correlation with national socioeconomic development. The global trends of DALY numbers in distance and/or near vision impairment as well as refractive and other causes remained stable from 1990 to 2015 (0.128 ≤ P ≤ 0.738), however, DALY rates had a statistically significant trend of reduction in all paediatric age groups (0.003 ≤ P ≤ 0.024). CONCLUSION: The global health burden of paediatric vision impairment decreased from 1990. Refractive, near vision impairment and other causes were associated with socioeconomic development.

Spatial distribution of diabetic capillary non-perfusion.

OBJECTIVE: To evaluate the distribution of capillary non-perfusion (CNP) in superficial and deep capillary plexuses (SCP and DCP) in eyes with diabetic retinopathy (DR). METHODS: In this retrospective case series, macular optical coherence tomography angiography (OCTA) images were obtained from eyes with DR without diabetic macular edema (DME). The area of CNP in SCP and DCP was delineated using an automated approach after excluding the foveal avascular zone (FAZ) and major retinal vessels. The distribution and spatial correlation of the CNP in each layer were analyzed. RESULTS: Forty-three eyes of 27 patients with DR with a mean age of 59.10 ± 9.05 years were included. The mean CNP area in SCP was statistically significantly higher than DCP (0.722 ± 0.437 mm2 vs. 0.184 ± 0.145 mm2 , respectively, p < .001). There was a statistically significant association between mean BCVA (0.28 ± 0.21 logMAR) and CNP area in DCP (p = .01). After automated subtraction of CNP areas in DCP from SCP, 25.43 ± 15.05% of CNP areas in the DCP had co-localized CNP areas in SCP. The CNP percentage was statistically significantly different between the concentric rings on foveal center, both in SCP and in DCP (both p < .001) showing a decreasing trend from the outer ring toward the center. CONCLUSION: In DR, SCP is more ischemic than DCP. This is in contrast to the previously described oxygenation-dependent ischemic cascade following acute retinal vascular occlusions. This study provides further insight into the retinal ischemia in DR.

Artifacts in Optical Coherence Tomography Angiography.

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.