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Despite the success of convolutional neural networks (CNNs) in numerous computer vision tasks and their extraordinary generalization performances, several attempts to predict the generalization errors of CNNs have only been limited to a posteriori analyses thus far. A priori theories explaining the generalization performances of deep neural networks have mostly ignored the convolutionality aspect and do not specify why CNNs are able to seemingly overcome curse of dimensionality on computer vision tasks like image classification where the image dimensions are in thousands. Our work attempts to explain the generalization performance of CNNs on image classification under the hypothesis that CNNs operate on the domain of image patches. Ours is the first work we are aware of to derive an a priori error bound for the generalization error of CNNs and we present both quantitative and qualitative evidences in the support of our theory. Our patch-based theory also offers explanation for why data augmentation techniques like Cutout, CutMix and random cropping are effective in improving the generalization error of CNNs.

Aims: To assess the differences in ocular morbidity with/without visual impairment between rural and urban school-going children using a two-step screening strategy. Methods: Data obtained by a hospital team from school camps conducted between the 1st of February 2019 and the 31st of December 2019, in schools with a strength of at least 1,000 students were reviewed retrospectively. The differences in ocular pathologies between the rural and urban cohorts were evaluated. A P < 0.05 was considered significant. Results: Out of 25,132 students (nurban = 12,562; nrural = 12,570), 14.44% (nurban = 1,585; nrural = 2,044; P < 0.001) were selected for evaluation by the hospital team after a primary screening by their class teachers. A statistically significant difference was noted in the frequency of refractive errors (urban = 6.8%; rural = 6.0%; P = 0.01), allergic conjunctivitis (urban = 0.2%; rural = 0.05%; P = 0.001), and amblyopia (urban = 0.03%; rural = 0.12%; P = 0.009) between urban and rural children. Simple and compound myopic astigmatism were significantly more common in urban children (p < 0.001 and 0.03 respectively). There was no significant difference in the incidence of spectacle use (P = 0.11) between the two cohorts. A Cochran--Armitage trend test revealed a statistically significant increase in the proportion of myopia with age among the children evaluated by the hospital team (p < 0.001). Conclusion: Allergic eye disease and myopic astigmatism are commoner in urban children. Routine ophthalmic screening is required to identify uncorrected refractive errors and amblyopia, especially in rural school children.

Purpose: In this advanced era, patients prefer to have reliable spectacle prescription after phacoemulsification at the earliest possible time. The purpose of this study is to find out the period of refraction stabilization after uneventful phacoemulsification in a tertiary eye care hospital in south India. Methodology: A prospective nonrandomized observational study at a tertiary surgical eye care centre in South India was conducted from January to June 2018, on 210 eyes of 210 consecutive patients with senile cataracts, who underwent uneventful phacoemulsification through 2.8 mm clear corneal incision. The refraction status of the subjects was evaluated at 1st week, 3rd week, and 3rd month postoperatively. One hundred seven patients were followed up till 3rd month. The remaining patients were followed up to 1 month. Patients were grouped into 1, 2, and 3 based on power variations in the range of 0–0.25 D, 0.5–0.75 D, 1 D, and more difference between visits, respectively. The changes were analyzed for spherical and cylindrical powers separately. Results: Almost 98.1% and 96.2% of patients were in Group 1 among spherical and cylindrical powers, respectively, when compared between second and third visits. About 84.3% and 67.1% were in Group 1 among spherical and cylindrical powers, respectively, when compared between first and second visits, but the difference was not statistically significant. The mean spherical equivalent showed no difference between all the three visits. Conclusion: Since there is no statistically significant difference of spherical and cylindrical values between visits, our prospective study concludes that reliable final refraction both by autorefraction and subjective refraction for spectacle prescription is possible as early as 1 week, in cases of clear cornea and quiet eye at 1 week postoperatively.

Purpose: To study the agreement of findings of glaucoma screening between trained vision center (VC) technicians and glaucoma specialists in patients referred from VC to the glaucoma services of a tertiary eye care hospital in south India. Methods: This was a retrospective study comparing the findings of the VC technicians and the specialists of the glaucoma services in the base hospital, in patients referred from 13 VCs between January and June 2019. Medical records of 277 referred patients (out of 533 referrals) who attended the glaucoma clinic were analyzed. Results: Of the 277 patients, 111 (40%) were confirmed having glaucoma, 133 (48%) were suspects, 29 (10.4%) were normal, and four (1.4%) had other pathology. The mean age of the patients was 59.7 ± 13 years and 60.6% were females. There was no statistically significant difference between the mean intraocular pressure (IOP) measured (17 ± 7.2 mmHg at the VC and 18 ± 8.7 mmHg at the clinic, p = 0.16) and the cup-to-disc ratio (CDR) (0.7 ± 0.13 at the VC and 0.6 ± 0.18 at the clinic, p = 0.57). Bland–Altman plots with 95% limits of agreement supported that mean differences were close to zero, and the intraclass correlation coefficient at 95% CI showed good consistency between the measurement of IOP (0.78 [0.74 to 0.81]) and CDR (0.90 [0.88 to 0.92]) at the base hospital and vision center. Conclusion: There is good agreement between the findings of VC technicians and glaucoma specialists. VC technicians can help in detecting glaucoma in the community.

Aims: The aim of this study is to analyze the outcomes of air descemetopexy with/without suture augmentation (AD) for Descemet's membrane detachment (DMD) post-cataract surgery. Materials and Methods: This prospective study included 51 eyes that underwent AD at a tertiary hospital. The outcome measures were successful Descemet's membrane (DM) reattachment and improvement in visual acuity by at least two Snellen lines. Statistical Analysis: Mean, standard deviation, and percentage were used to summarize the data. Wilcoxon signed-rank test, Chi-square test, and Fischer's exact test were used to calculate statistical significance. P < 0.05 was considered statistically significant. Results: Out of 52,396 cataract surgeries, 51 patients required surgical intervention for DMD, postoperatively. The mean age of the participants was 66.67 ± 9.8 years with a male: female ratio of 6:11. A nonplanar DMD was found in 56.87% (n = 29). The most common surgery preceding DMD was small incision cataract surgery (68.6%; n = 35). The mean interval between cataract surgery and descemetopexy was 9.3 ± 7.9 days. The mean pre- and post-descemetopexy visual acuities were 1.01 ± 0.6 and 0.44 ± 0.49, respectively (P < 0.00001). After an air tamponade, an additional suture (s) had to be placed in 62.8% (n = 32) cases, out of which 23 required a single suture, seven needed two sutures, and two needed three sutures. A successful DM reattachment was seen in 92.2% (n = 47) with the first attempt. There was a statistically significant improvement in visual acuity post-descemetopexy irrespective of the timing of surgery (P < 0.001 for all surgeries performed within 2 weeks and P = 0.03 for surgeries performed later). Conclusion: AD is a safe and effective procedure for the treatment of post-cataract surgery DMD.

The present protocol reports the ultrasound assisted synthesis of NiO nanoparticles(NPs) using benzylamine as a base and different types of cyclodextrins (CDs) as capping agents. The use of α-CD, β-CD or γ-CD leads to different morphologies of NiO NPs. In particular, NiO nanosheets obtained using β-CD as the capping agent. The synthesized NPs were characterized by FEG-SEM, TEM, XRD and EDS analysis. They showed high catalytic activity towards synthesis of different trisubstituted imidazoles under solvent free conditions. In addition, NiO NPs could be recycled and reused consecutively up to four recycle runs without much loss of their catalytic activity.

Pomegranate bacterial blight caused by Xanthomonas axonopodis pv. punicae (Xap) is a highly destructive disease. In the absence of host resistance to the disease, we aimed to evaluate the biocontrol potential of endophytic bacteria against Xap. Thus, in this study, we isolated endophytes from pomegranate plants, identified them on the basis of 16S rDNA sequencing, tested them against Xap, and estimated the endophyte-mediated host defense response. The population of isolated endophytes ranged from 3 × 106 to 8 × 107 CFU/g tissue. Furthermore, 26 isolates were evaluated for their biocontrol activity against Xap, and all the tested isolates significantly reduced the in vitro growth of Xap (15.65% ± 1.25% to 56.35% ± 2.66%) as compared to control. These isolates could reduce fuscan, an uncharacterized factor of Xap involved in its aggressiveness. Lower blight incidence (11.6%) and severity (6.1%) were recorded in plants sprayed with endophytes 8 days ahead of Xap spray (Set-III) as compared to control plants which were not exposed to endophytes (77.33 and 50%, respectively%) during in vivo evaluation. Moreover, significantly high phenolic and chlorophyll contents were estimated in endophyte-treated plants as compared to control. The promising isolates mostly belonged to the genera Bacillus, Burkholderia, and Lysinibacillus, and they were deposited to the National Agriculturally Important Microbial Culture Collection, India.

Here, we report a rare complication of the retropupillary iris claw intraocular lens (IOL) which in recent times has emerged as a good option for implantation in cases with inadequate capsular support following cataract surgery. Three weeks after undergoing iris claw IOL implantation, our patient presented with sudden decrease in visual acuity. On examination, we found the iris claw IOL to be tilted by 90° and lying perpendicular to the pupillary plane with the haptics still enclaved. Resurgery was done to reposition the IOL. The tremulousness of the iris causing an anterior movement of the iris diaphragm and IOL, aided by prolapse of vitreous could have caused the tilt.

PurposeTo identify the microbial aetiology of infectious endophthalmitis and to determine the in vitro antibacterial susceptibilities of bacterial isolates.MethodsA retrospective analysis was carried out of all patients presenting between January 1997 and December 2006 with clinically diagnosed infectious endophthalmitis who underwent microbiological evaluation. Intraocular specimens (aqueous and vitreous fluids) were collected from all cases of clinically suspected infectious endophthalmitis. In addition to intraocular aspirates, blood specimens from endogenous endophthalmitis, and corneal and scleral scrapes from relevant cases were also collected. The collected intraocular specimens, blood specimens, and corneal and scleral scrapes were subjected to microbiological evaluation.ResultsSamples from 955 patients with endophthalmitis underwent microbiological analysis, of which 424 (44.4%) were found to be culture positive. Of 424, 364 (85.8%) had bacterial growth and the remaining 60 (14.2%) had fungal growth. Among post-surgical endophthalmitis, Gram-negative bacilli (75%) were found to be the predominant cause for developing fulminant onset, Staphylococcus spp. (68.6%) for acute, and Streptococcus spp. (75%) for chronic onset of infections, whereas in post-traumatic endophthalmitis, Gram-negative bacilli (65.2%) were found to be the predominant cause for fulminant onset, Gram-positive bacillus (28.4%) for acute onset, and fungi (52.3%) for chronic onset of infections. Endophthalmitis associated with microbial keratitis was mainly caused by filamentous fungi (37.2%) and Gram-negative bacilli (37.2%). Overall, gatifloxacin (97.7%) showed highest activity against bacterial isolates followed by ciprofloxacin (95.9%) and ofloxacin (95.1%).ConclusionGram-negative bacilli cause predominantly fulminant onset, Staphylococci and Gram-positive bacilli acute, and Streptococci, Nocardia, and fungi chronic endophthalmitis. Gatifloxacin demonstrated greatest efficacy against these bacterial isolates.Eye (2009) 23, 945–956; doi:10.1038/eye.2008.197; published online 4 July 2008 [ABSTRACT FROM AUTHOR]

Electrocardiography is a valuable tool to aid in medical understanding and treatment of heart-related ailments, specifically atrial fibrillation (AF) and other irregular cardiac behavior. Although signs of AF will manifest in conventional electrocardiogram (ECG) recordings, interpretation and localization of AF sources require significant clinical expertise. In this vein, electrocardiographic imaging has emerged as an important medical imaging modality that provides reconstructions of the heart's electrical activity from non-invasive multi-lead body-surface ECG and anatomical x-ray computed tomography images. In this paper, we present a nonlinear inversion model for computing this mapping to improve upon the reconstruction performance of current methods. While contemporary techniques typically determine an inverse solution by discretizing and inverting an underdetermined linear system of partial differential equations governing the relationship between voltage potentials of the heart and torso, the presented technique re-casts this problem as a task in function approximation and provides a direct parameterization of the inverse operator using a polynomial neural network. That is, the outlined nonlinear inversion technique is a generalization of contemporary reconstruction techniques which allows geometrical and material parameterizations of the forward-model to be optimized using real experimental data collected from patients suffering from AF, as to better represent the inverse operator with respect to reconstruction metrics applicable to electrophysiology. The accuracy of our model is evaluated against a dataset of real-patient recordings to demonstrate its validity, and mathematical analysis is provided to support the polynomial expansion used in our inversion model.

Purpose: Pseudoexfoliation is an age-related fibrillopathy characterized by the deposition of fibrillar material in the eye with an increased risk of complications during cataract surgery. Aim was to study visual outcomes and complications in patients with pseudoexfoliation undergoing manual small-incision cataract surgery (MSICS)., Methods: Prospective observational study was performed on 152 patients with pseudoexfoliation above 50 years undergoing MSICS in a tertiary hospital from December 2016 to November 2017. Intraoperative and postoperative complications were documented with follow-up on postoperative day 1, 1 st week, 1 st month, and 3 rd month., Results: Preoperative small pupil was noted in 49 eyes (32.2%), and 19 (12.5%) required intraoperative measures. Intraocular complications noted were zonular dialysis in five (3.3%), posterior capsular rupture in one (0.7%), and iridodialysis in one (0.7%). On postoperative day 1, the most common complication was corneal edema in 134 patients but clinically significant in only 23 (15.1%). Postoperative complications at 3 months were irregular pupil in 17 cases and decentered IOL in three cases. Intraocular pressure decreased with each visit [preoperative mean: 14.39 (±3.4) and 13.37 (±2.0) 12.53 (±1.4) mm Hg at 1 and 3 months, respectively]. There was a significant improvement in vision from the first day mean pinhole vision of 0.26 (±0.24) to mean best corrected visual acuity (BCVA) of 0.09 (±0.22) and 0.07 (±0.22) at 1 and 3 months, respectively. Mean endothelial cell loss was 193.16 (7.79%) and 266.01 (10.68%) at 1 and 3 months, respectively., Conclusion: Pseudoexfoliation has an increased risk of complications during cataract surgery. MSICS gives good outcomes in terms of visual recovery and postoperative outcomes., Competing Interests: None

Purpose: To analyze the reasons for delay in cataract surgery in patients with advanced cataracts during the COVID-19 pandemic., Methods: This was a prospective, cross-sectional, multicenter questionnaire study which included patients with mature cataract, nuclear sclerotic cataract grade IV, and cataracts with best corrected visual acuity (BCVA) <5/60, during the COVID-19 pandemic from December 2020 to April 2021. Reasons for delay in presentation to the hospital were analyzed., Results: One thousand four hundred seventy two patients were recruited with advanced cataracts. Absence of ophthalmic care nearby (44.2%), lack of awareness regarding elective surgeries (42.6%), lack of public transportation (37%), fear of contracting COVID-19 (23.4%), and waiting for outreach camps (20.4%) were found to be the reasons behind the delay in cataract surgery. 53.7% of the patients had worsening of defective vision and 55.3% of them had difficulty in carrying out activities of family living. 30.8% of the patients faced difficulty in commuting and 8.4% of the patients suffered a fall during this pandemic due to worsening of the visual acuity., Conclusion: The lockdown imposed during the pandemic has created a significant backlog of patients who are progressing to advanced cataracts due to lack of ophthalmic care nearby, lack of awareness regarding elective surgeries, lack of public transportation, and no outreach camps. Proactive measures to deal with this backlog are of utmost need to prevent blindness due to cataract., Competing Interests: None

We herein describe a novel device to contain droplets and aerosols during phacoemulsification. We modified the silicon phaco test chamber into an aerosol containment chamber (ACC) by shortening the chamber and making a pear-shaped opening at one aspect of its tip. The ACC was fitted over phaco tip such that 4-5 mm of phaco tip and sleeve was exposed. When the phaco tip and irrigation port are inside the anterior chamber during phacoemulsification, the portion of the modified chamber remains around the clear corneal tunnel in an enclosing manner that contains aerosols and droplets., Competing Interests: None

Exfoliation syndrome (XFS) is the most common known risk factor for secondary glaucoma and a major cause of blindness worldwide. Variants in two genes, LOXL1 and CACNA1A, have previously been associated with XFS. To further elucidate the genetic basis of XFS, we collected a global sample of XFS cases to refine the association at LOXL1, which previously showed inconsistent results across populations, and to identify new variants associated with XFS. We identified a rare protective allele at LOXL1 (p.Phe407, odds ratio (OR) = 25, P = 2.9 × 10 -14 ) through deep resequencing of XFS cases and controls from nine countries. A genome-wide association study (GWAS) of XFS cases and controls from 24 countries followed by replication in 18 countries identified seven genome-wide significant loci (P < 5 × 10 -8 ). We identified association signals at 13q12 (POMP), 11q23.3 (TMEM136), 6p21 (AGPAT1), 3p24 (RBMS3) and 5q23 (near SEMA6A). These findings provide biological insights into the pathology of XFS and highlight a potential role for naturally occurring rare LOXL1 variants in disease biology.

Purpose: This study is aimed to determine the utility of various polymerase chain reaction (PCR) methods in vitreous fluids (VFs) for detecting the infectious genomes in the diagnosis of infectious endophthalmitis in terms of sensitivity and specificity., Methods: This prospective and consecutive analysis included a total of 66 VFs that were submitted for the microbiological evaluation, which were obtained from 66 clinically diagnosed endophthalmitis patients presented between November 2010 and October 2011 at the tertiary eye care referral centre in South India. Part of the collected VFs were subjected to cultures and smears, and the remaining parts were utilized for five PCR methods: uniplex, nested, semi-nested, multiplex and nested multiplex after extracting DNA, using universal eubacterial and Propionibacterium acnes species-specific primer sets targeting 16S rRNA gene in all bacteria and P. acnes, and panfungal primers, targeting 28S rRNA gene in all fungi., Results: Of the 66 VFs, five (7.5%) showed positive results in smears, 16 (24%) in cultures and 43 (65%) showed positive results in PCRs. Among the 43 positively amplified VFs, 10 (15%) were positive for P. acnes genome, one for panfungal genome and 42 (62%) for eubacterial genome (including 10 P. acnes positives). Among 42 eubacterial-positive VFs, 36 were positive by both uniplex (first round) and multiplex (first round) PCRs, while nested (second round) and nested multiplex (second round) PCRs produced positive results in 42 and 41 VFs, respectively. Of the 43 PCR-positive specimens, 16 (37%) had positive growth (15 bacterial and one fungal) in culture. Of 50 culture-negative specimens, 27 (54%) were showed positive amplification, of which 10 were amplified for both P. acnes and eubacterial genomes and the remaining 17 were for eubacterial genome alone., Conclusions: Nested PCRs are superior than uniplex and multiplex PCR. PCRs proved to be a powerful tool in the diagnosis of endophthalmitis, especially for detecting uncultured microbes.