Real-time line-field optical coherence tomography for cellular resolution imaging of biological tissue

A real-time line-field optical coherence tomography (LF-OCT) system is demonstrated with image acquisition rates of up to 5000 B-frames or 2.5 million A-lines per second for 500 A-lines per B-frame. The system uses a high-speed low-cost camera to achieve continuous data transfer rates required for real-time imaging, allowing the evaluation of future applications in clinical or intraoperative environments. The light source is an 840 nm super-luminescent diode. Leveraging parallel computing with GPU and high speed CoaXPress data transfer interface, we were able to acquire, process, and display OCT data with low latency. The studied system uses anamorphic beam shaping in the detector arm, optimizing the field of view and sensitivity for imaging biological tissue at cellular resolution. The lateral and axial resolution measured in air were 1.7 µm and 6.3 µm, respectively. Experimental results demonstrate real-time inspection of the trabecular meshwork and Schlemm's canal on ex vivo corneoscleral wedges and real-time imaging of endothelial cells of human subjects in vivo.

Rubella virus-associated necrotizing granulomatous inflammation with extensive eyelid, ocular, and orbital involvement

We present a case of cutaneous granulomatous disease associated with rubella virus in a 4-year-old girl without an identifiable immunodeficiency. In this case, a combination of anti-inflammatory, anti-viral, and anti-neutrophil therapies successfully treated vision-threatening eyelid, conjunctival, scleral, and orbital inflammation.

Corneal imaging with blue-light optical coherence microscopy

Corneal imaging is important for the diagnostic and therapeutic evaluation of many eye diseases. Optical coherence tomography (OCT) is extensively used in ocular imaging due to its non-invasive and high-resolution volumetric imaging characteristics. Optical coherence microscopy (OCM) is a technical variation of OCT that can image the cornea with cellular resolution. Here, we demonstrate a blue-light OCM as a low-cost and easily reproducible system to visualize corneal cellular structures such as epithelial cells, endothelial cells, keratocytes, and collagen bundles within stromal lamellae. Our blue-light OCM system achieved an axial resolution of 12 µm in tissue over a 1.2 mm imaging depth, and a lateral resolution of 1.6 µm over a field of view of 750 µm × 750 µm.

Differentiation of Active Corneal Infections from Healed Scars Using Deep Learning

PURPOSE

To develop and evaluate an automated, portable algorithm to differentiate active corneal ulcers from healed scars using only external photographs.

DESIGN

A convolutional neural network was trained and tested using photographs of corneal ulcers and scars.

PARTICIPANTS

De-identified photographs of corneal ulcers were obtained from the Steroids for Corneal Ulcers Trial (SCUT), Mycotic Ulcer Treatment Trial (MUTT), and Byers Eye Institute at Stanford University.

METHODS

Photographs of corneal ulcers (n = 1313) and scars (n = 1132) from the SCUT and MUTT were used to train a convolutional neural network (CNN). The CNN was tested on 2 different patient populations from eye clinics in India (n = 200) and the Byers Eye Institute at Stanford University (n = 101). Accuracy was evaluated against gold standard clinical classifications. Feature importances for the trained model were visualized using gradient-weighted class activation mapping.

MAIN OUTCOME MEASURES

Accuracy of the CNN was assessed via F1 score. The area under the receiver operating characteristic (ROC) curve (AUC) was used to measure the precision-recall trade-off.

RESULTS

The CNN correctly classified 115 of 123 active ulcers and 65 of 77 scars in patients with corneal ulcer from India (F1 score, 92.0% [95% confidence interval (CI), 88.2%-95.8%]; sensitivity, 93.5% [95% CI, 89.1%-97.9%]; specificity, 84.42% [95% CI, 79.42%-89.42%]; ROC: AUC, 0.9731). The CNN correctly classified 43 of 55 active ulcers and 42 of 46 scars in patients with corneal ulcers from Northern California (F1 score, 84.3% [95% CI, 77.2%-91.4%]; sensitivity, 78.2% [95% CI, 67.3%-89.1%]; specificity, 91.3% [95% CI, 85.8%-96.8%]; ROC: AUC, 0.9474). The CNN visualizations correlated with clinically relevant features such as corneal infiltrate, hypopyon, and conjunctival injection.

CONCLUSIONS

The CNN classified corneal ulcers and scars with high accuracy and generalized to patient populations outside of its training data. The CNN focused on clinically relevant features when it made a diagnosis. The CNN demonstrated potential as an inexpensive diagnostic approach that may aid triage in communities with limited access to eye care.

MULTIMODAL IMAGING OF TWO UNCONVENTIONAL CASES OF BARTONELLA NEURORETINITIS

PURPOSE

To report two cases of cat-scratch fever with atypical posterior segment manifestations.

METHODS

Two cases were retrospectively reviewed.

RESULTS

A 27-year-old woman presented with painless blurring of central vision in her left eye. Clinical examination revealed a small focal area of retinitis within the macula associated with a subtle macular star. Spectral-domain optical coherence tomography showed a hyper-reflective inner retinal lesion in addition to subretinal and intraretinal fluid as well as hyperreflective foci within the outer plexiform layer. Serology was positive for anti-B. henselae IgM (titer 1:32). A 34-year-old woman presented with painless loss of vision in both eyes associated with headaches and pain with extraocular movement. Spectral-domain optical coherence tomography depicted subretinal fluid, intraretinal fluid, and hyperreflective deposits within the outer plexiform layer. A focal collection of vitreous cell was observed overlying the optic nerve in the left eye. Bilateral disk leakage was identified on fluorescein angiography. Serology revealed high-titer anti-B. henselae antibodies (IgM titers 1:32, IgG titers 1:256).

CONCLUSION

Our cases highlight the necessity of recognizing more unusual posterior segment presentations of ocular bartonellosis. Multimodal retinal imaging including spectral-domain optical coherence tomography may help better characterize lesions.

Effect of Oral Azithromycin vs Placebo on COVID-19 Symptoms in Outpatients With SARS-CoV-2 Infection: A Randomized Clinical Trial

IMPORTANCE

Azithromycin has been hypothesized to have activity against SARS-CoV-2.

OBJECTIVE

To determine whether oral azithromycin in outpatients with SARS-CoV-2 infection leads to absence of self-reported COVID-19 symptoms at day 14.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial of azithromycin vs matching placebo conducted from May 2020 through March 2021. Outpatients from the US were enrolled remotely via internet-based surveys and followed up for 21 days. Eligible participants had a positive SARS-CoV-2 diagnostic test result (nucleic acid amplification or antigen) within 7 days prior to enrollment, were aged 18 years or older, and were not hospitalized at the time of enrollment. Among 604 individuals screened, 297 were ineligible, 44 refused participation, and 263 were enrolled. Participants, investigators, and study staff were masked to treatment randomization.

INTERVENTIONS

Participants were randomized in a 2:1 fashion to a single oral 1.2-g dose of azithromycin (n = 171) or matching placebo (n = 92).

MAIN OUTCOMES AND MEASURES

The primary outcome was absence of self-reported COVID-19 symptoms at day 14. There were 23 secondary clinical end points, including all-cause hospitalization at day 21.

RESULTS

Among 263 participants who were randomized (median age, 43 years; 174 [66%] women; 57% non-Hispanic White and 29% Latinx/Hispanic), 76% completed the trial. The trial was terminated by the data and safety monitoring committee for futility after the interim analysis. At day 14, there was no significant difference in proportion of participants who were symptom free (azithromycin: 50%; placebo: 50%; prevalence difference, 0%; 95% CI, -14% to 15%; P > .99). Of 23 prespecified secondary clinical end points, 18 showed no significant difference. By day 21, 5 participants in the azithromycin group had been hospitalized compared with 0 in the placebo group (prevalence difference, 4%; 95% CI, -1% to 9%; P = .16).

CONCLUSIONS AND RELEVANCE

Among outpatients with SARS-CoV-2 infection, treatment with a single dose of azithromycin compared with placebo did not result in greater likelihood of being symptom free at day 14. These findings do not support the routine use of azithromycin for outpatient SARS-CoV-2 infection.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04332107.

The Prognostic Value of Persistent Culture Positivity in Fungal Keratitis in the Mycotic Antimicrobial Localized Injection Trial

PURPOSE

To evaluate the utility of repeat cultures at days 3 and 7 after starting antifungal medications for predicting outcomes in fungal keratitis.

DESIGN

Prespecified secondary analysis of the randomized clinical Mycotic Antimicrobial Localized Injection trial.

METHODS

Patients presenting to Aravind Eye Hospital, Pondicherry, India, with fungal keratitis and visual acuity worse than 20/70 received topical natamycin and were randomized to either receive intrastromal injection of voriconazole or topical therapy alone. All subjects received corneal cultures at date of presentation, day 3, and day 7. Outcome measures included 3-week and 3-month visual acuity and scar size, corneal perforation, and/or the need for therapeutic penetrating keratoplasty (TPK). Visual acuity and scar size were analyzed with multiple linear regression controlling for baseline measures. Survival analysis was used to analyze the risk of corneal perforation and/or need for TPK.

RESULTS

Of the 70 study subjects with fungal keratitis, 25 of 69 (36%) remained culture positive at day 3, and 20 of 62 (32%) were culture positive at day 7. Culture positivity at day 3 conferred a hazard ratio of 2.8 for requiring TPK (P = .03) but was not a statistically significant predictor of perforation, scar size, or final visual acuity. Culture positivity at day 7 had a hazard ratio of 3.5 for requiring TPK (P = .003). Those with positive cultures at day 7 had on average 3 logMAR lines worse visual acuity at 3 months (95% confidence interval 0.9 to 5.2 logMAR lines, P = .006) and 1.1 mm larger scar size at 3 months after controlling for baseline measures (95% confidence interval 0.1 to 2.2 mm; P = .03).

CONCLUSIONS

While not as predictive as day 7 cultures, culture positivity at day 3 after starting treatment is a significant predictor of the need for TPK in patients with moderate-to-severe filamentous fungal keratitis. This has applications for risk stratification, and may facilitate earlier consideration of TPK in high-risk patients.

Using registry data to characterize the incidence and causes of blindness in Oregon

In the United States, there is no reliable data to describe the prevalence of eye diseases leading to visual impairment and little active surveillance to address this knowledge gap. Data that is readily available from many state blind registries may provide helpful information on trends and causes of blindness. We analyzed new registrations with the Oregon Commission for the Blind (OCB) and Oregon State Department of Administrative Services (DAS) from 1961 to 2016 for causes of and trends in blindness. Persons with blindness self-refer into the OCB registry and the Oregon State Department of Administrative Services (DAS) includes those receiving social security disability financial support and other state services. Data for 9,273 blind persons registered were analyzed. The most frequent causes of blindness were age related macular degeneration (AMD) 3,308 (38%), followed by diabetic retinopathy (DR) 729 (8%), congenital conditions 697 (8%), optic nerve atrophy 611 (7%), glaucoma 549 (6%), retinitis pigmentosa 546 (6%), retinopathy of prematurity192 (2%), cataract 180 (2%), and trauma 174 (2%). The mean age of onset of blindness was younger for Blacks (31 years) and Hispanics (33 years) than for Whites (44 years). Analysis of state-based registries can provide useful and locally relevant vision and eye health data where little information is otherwise available.

Bartonella presenting as branch retinal artery occlusion in a child

Branch retinal artery occlusion (BRAO) is rare in children. Bartonella is a known cause of branch retinal artery occlusion in adults, but it is typically not considered in the differential diagnosis for pediatric BRAO. We present the case of a 12-year old boy with a BRAO caused by a Bartonella henselae infection. This is the youngest such case reported in the literature. Although rare, Bartonella infection may be an important and underrecognized cause of pediatric BRAO.

The Impact and Implication of Peripheral Vascular Leakage on Ultra-Widefield Fluorescein Angiography in Uveitis

Purpose: To study if peripheral vascular leakage (PVL) on ultra-widefield fluorescein angiography (UWFFA) prognosticates complications of uveitis or necessitates treatment augmentation. Methods: Retrospective cohort study of uveitis patients imaged with UWFFA and ≥1 yr of follow-up. Results: We included 73 eyes of 42 patients with uveitis. There was no difference in baseline, intermediate, final visual acuity (p = 0.47-0.95) or rates of cystoid macular edema (CME) (p = 0.37-0.87) in eyes with PVL vs. those without. Eyes with PVL receiving baseline treatment augmentation were more likely to have baseline CME but were not more likely to have impaired visual acuity at final follow-up. PVL was independently associated with treatment augmentation on generalized estimating equation analysis with multivariable linear regression (OR: 4.39, p = 0.015). Conclusions: PVL did not confer an increased risk of impaired VA or CME at ≥1 yr follow-up but was possibly an independent driver of treatment augmentation.

Secretion of proteins by Coxiella burnetii

Viable Coxiella burnetii organisms were isolated from the culture medium of persistently infected Baby Hamster Kidney (BHK-21) fibroblasts. When these organisms were incubated in host-cell-free medium at low pH, some of the de novo-synthesized protein made by the bacteria was translocated to the exterior of the cell. The exported protein was detectable after 2-7 h incubation at 37 degrees C. No evidence was found to suggest that protein accumulation in the medium was due to leakiness caused by cell damage. Both DCCD (dicyclohexylcarbodiimide) and CCCP (carbonyl cyanide m-chlorophenylhydrazone) inhibited the process to some extent. Exported protein was represented largely by three polypeptides with molecular masses of 34, 24 and 12 kDa. De novo-synthesized proteins corresponding to these molecular masses were not detected in cytoplasmic fractions, but a membrane fraction might possess a similar form. It was concluded that a physiological process of protein translocation occurred in C. burnetii during acid activation in a defined medium. Organisms that were extracted directly from the cytoplasm of infected fibroblasts by a mechanical disruption procedure were also active in de novo protein synthesis; however they exported much less of the protein.