ssVERDICT: Self-supervised VERDICT-MRI for enhanced prostate tumor characterization.

PURPOSE: Demonstrating and assessing self-supervised machine-learning fitting of the VERDICT (vascular, extracellular and restricted diffusion for cytometry in tumors) model for prostate cancer. METHODS: We derive a self-supervised neural network for fitting VERDICT (ssVERDICT) that estimates parameter maps without training data. We compare the performance of ssVERDICT to two established baseline methods for fitting diffusion MRI models: conventional nonlinear least squares and supervised deep learning. We do this quantitatively on simulated data by comparing the Pearson's correlation coefficient, mean-squared error, bias, and variance with respect to the simulated ground truth. We also calculate in vivo parameter maps on a cohort of 20 prostate cancer patients and compare the methods' performance in discriminating benign from cancerous tissue via Wilcoxon's signed-rank test. RESULTS: In simulations, ssVERDICT outperforms the baseline methods (nonlinear least squares and supervised deep learning) in estimating all the parameters from the VERDICT prostate model in terms of Pearson's correlation coefficient, bias, and mean-squared error. In vivo, ssVERDICT shows stronger lesion conspicuity across all parameter maps, and improves discrimination between benign and cancerous tissue over the baseline methods. CONCLUSION: ssVERDICT significantly outperforms state-of-the-art methods for VERDICT model fitting and shows, for the first time, fitting of a detailed multicompartment biophysical diffusion MRI model with machine learning without the requirement of explicit training labels.

Hospital corneal retrieval program: A long way to go.

PURPOSE: The Hospital Corneal Retrieval Program (HCRP) aims to counsel and encourage the family of a critically ill or deceased person in the hospital for eye donation. Adequately sensitized health-care workers (HCWs) may play a pivotal role in boosting HCRP. STUDY DESIGN: Multicentric, cross-sectional, descriptive study. METHODS: Study participants included all HCWs of three medical colleges, including one with eye bank and corneal transplant services. A pretested, structured questionnaire was used to record the awareness, knowledge, and attitude about eye donation among HCWs. The expected outcome was to seek differences in awareness, if any, among medical and paramedical workers of medical colleges with (group A) or without (group B) eye bank and corneal transplant facilities. RESULTS: Of the 4060 study participants, 2100 HCWs were in group A and the rest (1960) were in group B. For eight out of 13 questions assessing awareness and perception, a statistically insignificant difference in responses was observed between the two groups. Regarding questions related to attitude, although the majority of HCWs in both groups were comfortable talking about eye donation, they did feel that counseling relatives of a terminally ill patient about eye donation was insensitive. Less than half of HCWs showed a willingness to donate eyes, and about half of the participants wanted to acquire more knowledge about eye donation. CONCLUSION: Awareness regarding eye donation among HCWs was mostly found to be at dismal levels, irrespective of whether they worked in an institute with or without eye bank and corneal transplant services. This warrants an accelerated effort at sensitizing HCWs as a strengthening measure for HCRP.

Comparison of Keratometric Change Following Various Conjunctival Autografting Techniques in Pterygium Surgery.

Aim To compare the postoperative keratometric changes and duration of surgery for different techniques of conjunctival autografting in pterygium surgery. Methods Patients with primary pterygium attending the outpatient department and having appropriate indications for surgery were enrolled. Preoperative ophthalmic examination included visual acuity assessment, refraction, keratometry, slit lamp, and fundus evaluation. Pterygium excision surgery with conjunctival autografting was performed on all patients using one of the four different techniques, namely, sutures, fibrin glue, and the autologous blood and bridge techniques. Duration of surgery was recorded for all patients. Postoperatively, all patients were followed up on Day 1, Day 7, and Months 1, 3, and 6. Duration of surgery, keratometric changes, and recurrence rates were analyzed in all four groups. Results Sixty-eight eyes of 66 patients completed the study protocol. There was a significant reduction in astigmatism after the autologous blood graft technique (P value 0.0055) and the glue technique (P value < 0.0001). The success rate of the autologous and glue technique was 90%. The glue technique was found to be more time efficient (mean duration 20.40 minutes) than other techniques. Conclusion After pterygium excision, conjunctival auto grafting using either autologous blood or glue plays a significant role in reducing pterygium-induced astigmatism and recurrence rates with the added advantage of a shorter operative time.

Validation of deep learning techniques for quality augmentation in diffusion MRI for clinical studies.

The objective of this study is to evaluate the efficacy of deep learning (DL) techniques in improving the quality of diffusion MRI (dMRI) data in clinical applications. The study aims to determine whether the use of artificial intelligence (AI) methods in medical images may result in the loss of critical clinical information and/or the appearance of false information. To assess this, the focus was on the angular resolution of dMRI and a clinical trial was conducted on migraine, specifically between episodic and chronic migraine patients. The number of gradient directions had an impact on white matter analysis results, with statistically significant differences between groups being drastically reduced when using 21 gradient directions instead of the original 61. Fourteen teams from different institutions were tasked to use DL to enhance three diffusion metrics (FA, AD and MD) calculated from data acquired with 21 gradient directions and a b-value of 1000 s/mm2. The goal was to produce results that were comparable to those calculated from 61 gradient directions. The results were evaluated using both standard image quality metrics and Tract-Based Spatial Statistics (TBSS) to compare episodic and chronic migraine patients. The study results suggest that while most DL techniques improved the ability to detect statistical differences between groups, they also led to an increase in false positive. The results showed that there was a constant growth rate of false positives linearly proportional to the new true positives, which highlights the risk of generalization of AI-based tasks when assessing diverse clinical cohorts and training using data from a single group. The methods also showed divergent performance when replicating the original distribution of the data and some exhibited significant bias. In conclusion, extreme caution should be exercised when using AI methods for harmonization or synthesis in clinical studies when processing heterogeneous data in clinical studies, as important information may be altered, even when global metrics such as structural similarity or peak signal-to-noise ratio appear to suggest otherwise.

Effect of atropine 0.01% on progression of myopia.

Purpose: Myopia is the most common type of refractive error and the leading cause of functional visual loss. Increased risk of myopic maculopathy, retinal detachment, glaucoma and cataract has been seen with a myopia of as low as -1D. This study was done to determine the effect of atropine 0.01% eye drops on the progression of myopia in children >5 years. Methods: This was a single-blind, prospective, randomized case-control study which included children of 5-15 years with myopia of >2D and were divided into treatment group (group 1) and placebo group (group 2). Children under treatment group were treated with application of 0.01% atropine at night. Children with history of any ocular surgery, chronic ophthalmic illness, squint and amblyopia were excluded from the study. The follow-up for myopia progression was done for two years. Results: This study showed a significant difference in increase of spherical equivalent and axial length among treatment and placebo groups after a duration of two years. Total duration of follow up was twenty-four months. Mean increase in axial length of group 1 and 2 was 0.115 mm and 0.32 mm, respectively. Mean increase in refraction of groups 1 and 2 was -0.30 D and -0.88 D, respectively, showing significant change in axial length and refraction (P < 0.0001). Conclusion: This study supports the use of atropine 0.01% eye drops in reducing the progression of myopia.

Analysis of COVID-19-associated rhino-orbital-cerebral mucormycosis patients in a tertiary care center in Northern India.

Purpose: An unprecedented surge has been noted in rhino-orbital-Cerebral mucormycosis (ROCM) in times of current COVID-19 pandemic. The present prospective study aims to evaluate clinico-epidemiological profile, risk factors, management, and outcome of the cases of ROCM that presented to our tertiary care center during the study period from April to June 2021. Methods: All patients were subjected to complete history taking, ophthalmological examination, and imaging studies. The patients were staged and were treated with intravenous liposomal amphotericin B (AMB) and sino-nasal debridement of local necrotic tissue. Transcutaneous retrobulbar AMB (TRAMB), orbital decompression, and exenteration were instituted as indicated. All patients were followed up for a minimum of 6 months before arriving at the final outcome. Statistical analysis was performed. Results: A total of 49 patients presented during the study period, with a mean age of 42.2 years. The major risk factors included uncontrolled diabetes (89.8%), COVID-19 positivity (51.02%), and concurrent steroid use (38.77%). The most common presenting symptom was facial pain/swelling (43.65%), while the most common presenting sign was deterioration in vision (75.51%). Intravenous liposomal AMB was given to all patients along with sino-nasal debridement (85.71%), TRAMB (57.14%), orbital decompression (14.28%), and exenteration (12.24%). Overall, mortality at 6 months was 22.45% (11 patients). Age more than 60 years, intracranial extension, and HbA1c of more than 8.0% were observed to be statistically significant indicators of mortality. Conclusion: Early suspicion and timely diagnosis of mucormycosis at rhino-orbital stage is warranted in order to salvage life as well as visual function. TRAMB may prove as potentially favorable treatment modality in cases with limited orbital involvement.

Differentiating False Positive Lesions from Clinically Significant Cancer and Normal Prostate Tissue Using VERDICT MRI and Other Diffusion Models.

False positives on multiparametric MRIs (mp-MRIs) result in many unnecessary invasive biopsies in men with clinically insignificant diseases. This study investigated whether quantitative diffusion MRI could differentiate between false positives, true positives and normal tissue non-invasively. Thirty-eight patients underwent mp-MRI and Vascular, Extracellular and Restricted Diffusion for Cytometry in Tumors (VERDICT) MRI, followed by transperineal biopsy. The patients were categorized into two groups following biopsy: (1) significant cancer­true positive, 19 patients; (2) atrophy/inflammation/high-grade prostatic intraepithelial neoplasia (PIN)­false positive, 19 patients. The clinical apparent diffusion coefficient (ADC) values were obtained, and the intravoxel incoherent motion (IVIM), diffusion kurtosis imaging (DKI) and VERDICT models were fitted via deep learning. Significant differences (p < 0.05) between true positive and false positive lesions were found in ADC, IVIM perfusion fraction (f) and diffusivity (D), DKI diffusivity (DK) (p < 0.0001) and kurtosis (K) and VERDICT intracellular volume fraction (fIC), extracellular−extravascular volume fraction (fEES) and diffusivity (dEES) values. Significant differences between false positives and normal tissue were found for the VERDICT fIC (p = 0.004) and IVIM D. These results demonstrate that model-based diffusion MRI could reduce unnecessary biopsies occurring due to false positive prostate lesions and shows promising sensitivity to benign diseases.

The effect of smoking on ocular surface and tear film based on clinical examination and optical coherence tomography.

PURPOSE: Smoking is a global health problem with a high burden of smokers in India and the world as well. Smoking is a known eye irritant that may have a significant effect on the anterior ocular surface. Hence, the present study was aimed to investigate the effect of smoking on dry eye parameters, ocular surface, and central corneal thickness (CCT) and to compare the results with nonsmokers. METHODS: In this cross-sectional study, 40 (80 eyes) smokers and 40 (80 eyes) age-matched nonsmokers were included. The severity of ocular surface disease symptoms was assessed by the Ocular Surface Disease Index (OSDI) tool. All participants underwent a series of measurements, that is, the Schirmer's II test score and tear breakup time (TBUT). Tear meniscus height (TMH) and CCT were measured using anterior segment optical coherence tomography (OCT). RESULTS: The mean value of all dry eye parameters was statistically different among the group of smokers and nonsmokers. The mean score of symptomatic assessment (OSDI) was observed to be significantly higher in smokers than in nonsmokers (P < 0.0001), and dry eye parameters, that is, Schirmer's score (P = 0.0127), TMH (P < 0.0001), and TBUT (P < 0.0001) were significantly lower among smokers than nonsmokers. There was no significant difference in CCT between smokers and nonsmokers (P = 0.06). CONCLUSION: Cigarette smoking has deteriorating effects on the ocular surface. Exposure to smoking was found to be associated with dryness of the eye. Further studies are needed on a molecular basis.