The Role of Different Retinal Imaging Modalities in Predicting Progression of Diabetic Retinopathy: A Survey.

Diabetic retinopathy (DR) is a devastating condition caused by progressive changes in the retinal microvasculature. It is a leading cause of retinal blindness in people with diabetes. Long periods of uncontrolled blood sugar levels result in endothelial damage, leading to macular edema, altered retinal permeability, retinal ischemia, and neovascularization. In order to facilitate rapid screening and diagnosing, as well as grading of DR, different retinal modalities are utilized. Typically, a computer-aided diagnostic system (CAD) uses retinal images to aid the ophthalmologists in the diagnosis process. These CAD systems use a combination of machine learning (ML) models (e.g., deep learning (DL) approaches) to speed up the diagnosis and grading of DR. In this way, this survey provides a comprehensive overview of different imaging modalities used with ML/DL approaches in the DR diagnosis process. The four imaging modalities that we focused on are fluorescein angiography, fundus photographs, optical coherence tomography (OCT), and OCT angiography (OCTA). In addition, we discuss limitations of the literature that utilizes such modalities for DR diagnosis. In addition, we introduce research gaps and provide suggested solutions for the researchers to resolve. Lastly, we provide a thorough discussion about the challenges and future directions of the current state-of-the-art DL/ML approaches. We also elaborate on how integrating different imaging modalities with the clinical information and demographic data will lead to promising results for the scientists when diagnosing and grading DR. As a result of this article's comparative analysis and discussion, it remains necessary to use DL methods over existing ML models to detect DR in multiple modalities.

The Risk of Postoperative Complications After Major Elective Surgery in Active or Resolved COVID-19 in the United States.

OBJECTIVE: To assess the association between the timing of surgery relative to the development of Covid-19 and the risks of postoperative complications. SUMMARY BACKGROUND DATA: It is unknown whether patients who recovered from Covid-19 and then underwent a major elective operation have an increased risk of developing postoperative complications. METHODS: The risk of postoperative complications for patients with Covid-19 undergoing 18 major types of elective operations in the Covid-19 Research Database was evaluated using multivariable logistic regression. Patients were grouped by time of surgery relative to SARS-CoV-2 infection; that is, surgery performed: (1) before January 1, 2020 ("pre-Covid-19"), (2) 0 to 4 weeks after SARS-CoV-2 infection ("peri-Covid-19"), (3) 4 to 8 weeks after infection ("early post-Covid-19"), and (4) ≥8 weeks after infection ("late post-Covid-19"). RESULTS: Of the 5479 patients who met study criteria, patients with peri-Covid-19 had an elevated risk of developing postoperative pneumonia [adjusted odds ratio (aOR), 6.46; 95% confidence interval (CI): 4.06-10.27], respiratory failure (aOR, 3.36; 95% CI: 2.22-5.10), pulmonary embolism (aOR, 2.73; 95% CI: 1.35-5.53), and sepsis (aOR, 3.67; 95% CI: 2.18-6.16) when compared to pre-Covid-19 patients. Early post-Covid-19 patients had an increased risk of developing postoperative pneumonia when compared to pre-Covid-19 patients (aOR, 2.44; 95% CI: 1.20-4.96). Late post-Covid-19 patients did not have an increased risk of postoperative complications when compared to pre-Covid-19 patients. CONCLUSIONS: Major, elective surgery 0 to 4 weeks after SARS-CoV-2 infection is associated with an increased risk of postoperative complications. Surgery performed 4 to 8 weeks after SARS-CoV-2 infection is still associated with an increased risk of postoperative pneumonia, whereas surgery 8 weeks after Covid-19 diagnosis is not associated with increased complications.

Regulation of the parental gene GRM4 by circGrm4 RNA transcript and glutamate-mediated neurovascular toxicity in eyes.

Epigenetic memory plays crucial roles in gene regulation. It not only modulates the expression of specific genes but also has ripple effects on transcription as well as translation of other genes. Very often an alteration in expression occurs either via methylation or demethylation. In this context, "1-carbon metabolism" assumes a special significance since its dysregulation by higher levels of homocysteine; Hcy (known as hyperhomocysteinemia; HHcy), a byproduct of "1-Carbon Metabolism" during methionine biosynthesis leads to serious implications in cardiovascular, renal, cerebrovascular systems, and a host of other conditions. Currently, the circular RNAs (circRNAs) generated via non-canonical back-splicing events from the pre-mRNA molecules are at the center stage for their essential roles in diseases via their epigenetic manifestations. We recently identified a circular RNA transcript (circGRM4) that is significantly upregulated in the eye of cystathionine ß-synthase-deficient mice. We also discovered a concurrent over-expression of the mGLUR4 receptor in the eyes of these mice. In brief, circGRM4 is selectively transcribed from its parental mGLUR4 receptor gene (GRM4) functions as a "molecular-sponge" for the miRNAs and results into excessive turnover of the mGLUR4 receptor in the eye in response to extremely high circulating glutamate concentration. We opine that this epigenetic manifestation potentially predisposes HHcy people to retinovascular malfunctioning.

A convolutional neural network for the screening and staging of diabetic retinopathy.

Diabetic retinopathy (DR) is a serious retinal disease and is considered as a leading cause of blindness in the world. Ophthalmologists use optical coherence tomography (OCT) and fundus photography for the purpose of assessing the retinal thickness, and structure, in addition to detecting edema, hemorrhage, and scars. Deep learning models are mainly used to analyze OCT or fundus images, extract unique features for each stage of DR and therefore classify images and stage the disease. Throughout this paper, a deep Convolutional Neural Network (CNN) with 18 convolutional layers and 3 fully connected layers is proposed to analyze fundus images and automatically distinguish between controls (i.e. no DR), moderate DR (i.e. a combination of mild and moderate Non Proliferative DR (NPDR)) and severe DR (i.e. a group of severe NPDR, and Proliferative DR (PDR)) with a validation accuracy of 88%-89%, a sensitivity of 87%-89%, a specificity of 94%-95%, and a Quadratic Weighted Kappa Score of 0.91-0.92 when both 5-fold, and 10-fold cross validation methods were used respectively. A prior pre-processing stage was deployed where image resizing and a class-specific data augmentation were used. The proposed approach is considerably accurate in objectively diagnosing and grading diabetic retinopathy, which obviates the need for a retina specialist and expands access to retinal care. This technology enables both early diagnosis and objective tracking of disease progression which may help optimize medical therapy to minimize vision loss.

Hydrogen sulfide intervention in cystathionine-ß-synthase mutant mouse helps restore ocular homeostasis.

AIM: To investigate the applications of hydrogen sulfide (H2S) in eye-specific ailments in mice. METHODS: Heterozygous cystathionine-ß-synthase (CBS+/-) and wild-type C57BL/6J (WT) mice fed with or without high methionine diet (HMD) were administered either phosphate buffered saline (PBS) or the slow-release H2S donor: GYY4137. Several analyses were performed to study GYY4137 effects by examining retinal lysates for key protein expressions along with plasma glutamate and glutathione estimations. Intraocular pressure (IOP) was monitored during GYY4137 treatment; barium sulfate and bovine serum albumin conjugated fluorescein isothiocyanate (BSA-FITC) angiographies were performed for examining vasculature and its permeability post-treatment. Vision-guided behavior was also tested employing novel object recognition test (NORT) and light-dark box test (LDBT) recordings. RESULTS: CBS deficiency (CBS+/-) coupled with HMD led disruption of methionine/homocysteine (Hcy) metabolism leading to hyperhomocysteinemia (HHcy) in CBS+/- mice as reflected by increased Hcy, and s-adenosylhomocysteine hydrolase (SAHH) levels. Unlike CBS, cystathionine-γ lyase (CSE), methylenetetrahydrofolate reductase (MTHFR) levels which were reduced but compensated by GYY4137 intervention. Heightened oxidative and endoplasmic reticulum (ER) stress responses were mitigated by GYY4137 effects along with enhanced glutathione (GSH) levels. Increased glutamate levels in CBS+/- strain were prominent than WT mice and these mice also exhibited higher IOP that was lowered by GYY4137 treatment. CBS deficiency also resulted in vision-guided behavioral impairment as revealed by NORT and LDBT findings. Interestingly, GYY4137 was able to improve CBS+/- mice behavior together with lowering their glutamate levels. Blood-retinal barrier (BRB) appeared compromised in CBS+/- with vessels' leakage that was mitigated in GYY4137 treated group. This corroborated the results for occludin (an integral plasma membrane protein of the cellular tight junctions) stabilization. CONCLUSION: Findings reveal that HHcy-induced glutamate excitotoxicity, oxidative damage, ER-stress and vascular permeability alone or together can compromise ocular health and that GYY4137 could serve as a potential therapeutic agent for treating HHcy induced ocular disorders.

FREQUENT SUBCLINICAL MACULAR CHANGES IN COMBINED BRAF/MEK INHIBITION WITH HIGH-DOSE HYDROXYCHLOROQUINE AS TREATMENT FOR ADVANCED METASTATIC BRAF MUTANT MELANOMA: Preliminary Results From a Phase I/II Clinical Treatment Trial.

PURPOSE: To assess the potential ocular toxicity of a combined BRAF inhibition (BRAFi) + MEK inhibition (MEKi) + hydroxychloroquine (HCQ) regime used to treat metastatic BRAF mutant melanoma. METHODS: Patients with stage IV metastatic melanoma and BRAF V600E mutations (n = 11, 31-68 years of age) were included. Treatment was with oral dabrafenib, 150 mg bid, trametinib, 2 mg/day, and HCQ, 400 mg to 600 mg bid. An ophthalmic examination, spectral domain optical coherence tomography, near-infrared and short-wavelength fundus autofluorescence, and static perimetry were performed at baseline, 1 month, and q/6 months after treatment. RESULTS: There were no clinically significant ocular events; there was no ocular inflammation. The only medication-related change was a separation of the photoreceptor outer segment tip from the apical retinal pigment epithelium that could be traced from the fovea to the perifoveal retina noted in 9/11 (82%) of the patients. There were no changes in retinal pigment epithelium melanization or lipofuscin content by near-infrared fundus autofluorescence and short-wavelength fundus autofluorescence, respectively. There were no inner retinal or outer nuclear layer changes. Visual acuities and sensitivities were unchanged. CONCLUSION: BRAFi (trametinib) + MEKi (dabrafenib) + HCQ causes very frequent, subclinical separation of the photoreceptor outer segment from the apical retinal pigment epithelium without inner retinal changes or signs of inflammation. The changes suggest interference with the maintenance of the outer retinal barrier and/or phagocytic/pump functions of the retinal pigment epithelium by effective MEK inhibition.

ACUTE EXUDATIVE PARANEOPLASTIC POLYMORPHOUS VITELLIFORM MACULOPATHY DURING VEMURAFENIB AND PEMBROLIZUMAB TREATMENT FOR METASTATIC MELANOMA.

PURPOSE: To describe a patient with BRAF mutation-positive cutaneous melanoma who developed acute exudative polymorphous vitelliform maculopathy during vemurafenib and pembrolizumab treatment for metastatic melanoma. METHODS: Retrospective case report documented with wide-field fundus imaging, spectral domain optical coherence tomography, and fundus autofluorescence imaging. RESULTS: A 55-year-old woman with bilateral ductal breast carcinoma and BRAF mutation-positive metastatic cutaneous melanoma complained of bilateral blurred vision within 5 days of starting vemurafenib (BRAF inhibitor). She had been on pembrolizumab (program death receptor antibody) and intermittently on dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor), and had a normal ophthalmologic examination. On presentation three weeks after the introduction of vemurafenib, her visual acuity had declined to 20/40 in both eyes. Her examination showed diffuse elevation of the fovea with multifocal yellow-white, crescent-shaped subretinal deposits within the macula of both eyes and bilateral neurosensory retinal detachments by spectral domain optical coherence tomography. Discontinuation of vemurafenib and introduction of difluprednate and dorzolamide led to a gradual resolution (over four months) of the neurosensory detachments with recovery of vision. CONCLUSION: This case report suggests that acute exudative polymorphous vitelliform maculopathy may be directly associated with the use of BRAF inhibitors as treatment for metastatic cutaneous melanoma, or indirectly by triggering autoimmune-paraneoplastic processes. Future identification of similar associations is required to unequivocally link vemurafenib and/or pembrolizumab to acute exudative polymorphous vitelliform maculopathy in metastatic melanoma.

A hypothesis for treating inflammation and oxidative stress with hydrogen sulfide during age-related macular degeneration.

Age-related macular degeneration (AMD) is a leading cause of blindness and is becoming a global crisis since affected people will increase to 288 million by 2040. Genetics, age, diabetes, gender, obesity, hypertension, race, hyperopia, iris-color, smoking, sun-light and pyroptosis have varying roles in AMD, but oxidative stress-induced inflammation remains a significant driver of pathobiology. Eye is a unique organ as it contains a remarkable oxygen-gradient that generates reactive oxygen species (ROS) which upregulates inflammatory pathways. ROS becomes a source of functional and morphological impairments in retinal pigment epithelium (RPE), endothelial cells and retinal ganglion cells. Reports demonstrated that hydrogen sulfide (H2S) acts as a signaling molecule and that it may treat ailments. Therefore, we propose a novel hypothesis that H2S may restore homeostasis in the eyes thereby reducing damage caused by oxidative injury and inflammation. Since H2S has been shown to be a powerful antioxidant because of its free-radicals' inhibition properties in addition to its beneficial effects in age-related conditions, therefore, patients may benefit from H2S salubrious effects not only by minimizing their oxidant and inflammatory injuries to retina but also by lowering retinal glutamate excitotoxicity.

Circular RNAs profiling in the cystathionine-ß-synthase mutant mouse reveals novel gene targets for hyperhomocysteinemia induced ocular disorders.

Cystathionine-ß-synthase (CBS) gene encodes L-serine hydrolyase which catalyzes ß-reaction to condense serine with homocysteine (Hcy) by pyridoxal-5'-phosphate helps to form cystathionine which in turn is converted to cysteine. CBS resides at the intersection of transmethylation, transsulfuration, and remethylation pathways, thus lack of CBS fundamentally blocks Hcy degradation; an essential step in glutathione synthesis. Redox homeostasis, free-radical detoxification and one-carbon metabolism (Methionine-Hcy-Folate cycle) require CBS and its deficiency leads to hyperhomocysteinemia (HHcy) causing retinovascular thromboembolism and eye-lens dislocation along with vascular cognitive impairment and dementia. HHcy results in retinovascular, coronary, cerebral and peripheral vessels' dysfunction and how it causes metabolic dysregulation predisposing patients to serious eye conditions remains unknown. HHcy orchestrates inflammation and redox imbalance via epigenetic remodeling leading to neurovascular pathologies. Although circular RNAs (circRNAs) are dominant players regulating their parental genes' expression dynamics, their importance in ocular biology has not been appreciated. Progress in gene-centered analytics via improved microarray and bioinformatics are enabling dissection of genomic pathways however there is an acute under-representation of circular RNAs in ocular disorders. This study undertook circRNAs' analysis in the eyes of CBS deficient mice identifying a pool of 12532 circRNAs, 74 exhibited differential expression profile, ∼27% were down-regulated while most were up-regulated (∼73%). Findings also revealed several microRNAs that are specific to each circRNA suggesting their roles in HHcy induced ocular disorders. Further analysis of circRNAs helped identify novel parental genes that seem to influence certain eye disease phenotypes.

Benign Reactive Lymphoid Hyperplasia of the Conjunctiva Treated With Cyclosporine.

PURPOSE: To describe a case of reactive lymphoid hyperplasia (RLH) of the conjunctiva responding to cyclosporine immunosuppressant monotherapy. METHODS: A 66-year-old man with a 2-year history of biopsy-proven bilateral RLH presented for dry eye evaluation with chief complaints of burning, stinging, and irritation in both eyes. After slit-lamp examination and positive findings of matrix metalloproteinase 9 in the patient's tear film, he was diagnosed with meibomian gland dysfunction and tear-insufficiency dry eye disease. The patient was subsequently treated with topical cyclosporine (ophthalmic emulsion 0.5 mg/mL two times per day) in both eyes. RESULTS: Examination at the 3-month follow-up visit revealed significant reduction of the RLH lesions bilaterally. CONCLUSIONS: This report represents the first case of benign ocular RLH responsive to topical cyclosporine therapy. We believe that cyclosporine could play a role in treating patients with benign ocular RLH and warrants further investigation to evaluate its full efficacy.

Evaluation of lipid peroxidation and antioxidant status on fenvalerate, nitrate and their co-exposure in Bubalus bubalis.

The toxic effects of pesticides and minerals have been explored in different species, but still there is paucity of information regarding their combined toxicological effects. The present investigation reports oxidative stress induced by oral subacute exposure to fenvalerate (1 mg/kg) and sodium nitrate (20 mg/kg) alone, as well as in combination daily for 21 days in buffalo calves. Fenvalerate exposure produced significant elevation in lipid peroxidation (LPO), glutathione peroxidase (GPx), while it produced significant decline in blood glutathione (GSH) levels, superoxide dismutase (SOD) and catalase (CAT). No significant alteration was evidenced in nitric oxide (NOx) levels. Oral exposure to sodium nitrate produced significant inclination in LPO and NOx, while on the other hand significant depreciation in SOD and CAT with no significant change in GPx activity. Combined exposure to fenvalerate and sodium nitrate produced severe effects with an appreciably more prominent elevation in extent of LPO and decline in blood GSH levels.

Surgical outcomes after epiretinal membrane peeling combined with cataract surgery.

OBJECTIVE: To compare functional and anatomical outcomes after idiopathic epiretinal membrane (ERM) peeling combined with phacoemulsification and intraocular lens implantation versus ERM peeling alone. METHODS: A retrospective, non-randomised comparative case series study was conducted of 81 eyes from 79 patients who underwent ERM peeling at the Beth Israel Deaconess Medical Center between 2001 and 2010. Eyes that underwent combined surgery for ERM and cataracts (group 1) were compared with those that had ERM peeling alone (group 2) with respect to best-corrected visual acuity at 6 months and 1 year after surgery, postoperative central macular thickness (CMT) as measured on optical coherence tomography, and rates of complications, including elevated intraocular pressure (IOP), ERM recurrence and need for reoperation. RESULTS: Mean logMAR visual acuity improved significantly in both groups at 6 months (p<0.001) and 1 year (p<0.001) after surgery. There was no statistical difference between the two groups in visual acuity improvement at 6 months (p=0.108) or 1 year (p=0.094). Mean CMT of both groups also significantly decreased after surgery (p=0.002), with no statistical difference in CMT reduction between the two groups, but a trend toward less CMT reduction in group 1 (p=0.061). The rates of complications, including IOP elevation, ERM recurrence and frequency of reoperation, were similar in the two groups, with non-statistical trends toward greater ERM recurrence (p=0.084) and need for reoperation (p=0.096) in those that had combined surgery. CONCLUSIONS: Combined surgery for ERMs and cataracts may potentially be as effective as membrane peeling alone with respect to visual and anatomical outcomes. Further studies are necessary to determine if there may be greater ERM recurrence or need for reoperation after combined surgery.

Bilateral conjunctival melanocytic nevi of simultaneous onset simulating conjunctivitis in a child.

A healthy 10-year-old girl developed synchronous, bilateral, temporal redness of the eyes regarded as sectoral conjunctivitis for 5 years that was unresponsive to topical steroids and antihistamines. Finely vascularized, minimally elevated, amelanotic or faintly focally pigmented, epibulbar conjunctival lesions were present bilaterally. The lesions were completely excised. Histopathologic and immunohistochemical evaluations confirmed that they were both predominantly junctional nevi with conspicuous chronic inflammation. Juvenile conjunctival nevi frequently have atypical histopathologic traits that in an adult could be suggestive of melanoma. The differential diagnosis of much less likely disorders includes leukemia, lymphoid tumor (salmon patch), and conjunctival sarcoidosis, among other conditions. The patient has had no recurrence 3 years after surgery.

Plasma levels, pharmacokinetics and dosage regimen of intravenously administered gatifloxacin in buffalo calves (Bubalus bubalis) on coadministration with meloxicam / Os níveis plasmáticos, farmacocinética e regime de dosagem de gatifloxacina administrado por via intravenosa em bezerros búfalos (Bubalus bubalis) na administração concomitante com meloxicam

The pharmacokinetics of intravenously administered gatifloxacin, upon concomitant administration with meloxicam was investigated in buffalo calves. Meloxicam was administered subcutaneously (0.5 mg.kg-1) immediately followed by intravenous administration of Gatifloxacin (4 mg.kg-1). The concentration of gatifloxacin was estimated in plasma by microbiological assay. Pharmacokinetic parameters were calculated and appropriate dosage schedule was computed. The therapeutic plasma drug concentration was maintained up to 12 h. Gatifloxacin was rapidly distributed from blood to tissue compartment, which was evident from the high values of distribution rate constant, α1 (11.9 ± 0.52 h-1) and the ratio of rate constant of transfer of drug from central to peripheral compartments and vice versa, K12/K21 (3.05 ± 0.36) and K13/K31 (2.04 ± 0.12). The area under the plasma drug concentration-time curve and apparent volume of distribution were 12.0 ± 0.68 µg.ml-1.h and 2.69 ± 0.14 L.kg-1, respectively. The elimination half-life (t1/2β), total body clearance (ClB) and the ratio of drug present in peripheral to central compartment (P/C) were 5.59 ± 0.40 h, 337.6 ± 19.9 ml.kg-1.h-1 and 8.04 ± 0.50, respectively. The present study revealed that the most suitable dosage regimen of gatifloxacin when concomitantly administered with meloxicam in buffalo calves would be 2.5 mg.kg-1 followed by 2.0 mg.kg-1 at 12 h intervals.

Investigou-se a farmacocinética da gatifloxacina, administrada por via intravenosa, concomitante à aplicação de meloxicam em bezerros búfalos. O meloxicam foi administrado por via subcutânea (0,5 mg.kg-1), imediatamente seguido pela administração intravenosa de gatifloxacina (4 mg.kg-1). A concentração plasmática de gatifloxacina foi estimada por ensaio microbiológico. Os parâmetros farmacocinéticos foram calculados e a posologia adequada foi computada. A concentração plasmática do fármaco-terapêutico foi mantida por 12 h. A gatifloxacina foi rapidamente distribuída a partir de sangue para o compartimento de tecido, o que ficou evidente a partir dos valores elevados da taxa constante de distribuição, α1 (11.9 ± 0.52 h-1) e a proporção de velocidade constante de transferência de droga a partir de centrais para os compartimentos periféricos e vice-versa, K12/K21 (3.05 ± 0.36) e K13/K31 (2.04 ± 0.12). A área sob a curva plasmática de concentração-tempo da droga e o volume aparente de distribuição foi de 12.0 ± 0.68 µg.ml-1.h e 2.69 ± 0.14 L.kg-1, respectivamente. A meia-vida (t1/2β), a depuração corporal total (ClB) e relação da droga presente no sangue periférico para o compartimento central (P/C) foram 5.59 ± 0.40 h, 337.6 ± 19.9 ml.kg-1.h-1 e 8.04 ± 0.50, respectivamente. O presente estudo revelou que o regime de dosagem mais adequado de gatifloxacina quando administrada concomitantemente com meloxicam em bezerros búfalos seria 2,5 mg.kg-1 seguida de 2,0 mg.kg-1 em intervalos de 12 h.