Retinal Vascular Changes in Response to Hypoxia: A High-Altitude Expedition Study

Westwood, Jessica, India Mayhook-Walker, Ciaran Simpkins, Andrew Darby-Smith, Dan Morris, and Eduardo Normando. Retinal vascular changes in response to hypoxia: a high-altitude expedition study. High Alt Med Biol. 25:49-59, 2024. Background: Increased tortuosity and engorgement of retinal vasculature are recognized physiological responses to hypoxia. This can lead to high-altitude retinopathy (HAR), but incidence reports are highly variable, and our understanding of the etiological mechanisms remains incomplete. This study quantitatively evaluated retinal vascular changes during an expedition to 4,167 m. Methods: Ten healthy participants summited Mount Toubkal, Morocco. Fundus images were taken predeparture, daily throughout the expedition, and 1 month postreturn. Diameter and tortuosity of four vessels were assessed, in addition to vessel density and features of HAR. Results: Significant (p ≤ 0.05) increases in tortuosity and diameter were observed in several vessels on high-altitude exposure days. There was a strong correlation between altitude and supratemporal retinal artery diameter on days 2, 3, and 6 of the expedition (r = 0.7707, 0.7951, 0.7401, respectively; p < 0.05). There was a significant increase in median vessel density from 6.7% at baseline to 10.0% on summit day. Notably there were no incidences of HAR. Conclusion: Physiological but not pathological changes were seen in this cohort, which gives insight into the state of the cerebral vasculature throughout this expedition. These results are likely attributable to relatively low altitude exposure, a conservative ascent profile, and the cohort's demographic. Future study must include daily retinal images at higher altitudes and take steps to mitigate environmental confounders. This study is relevant to altitude tourists, patients with diabetic retinopathy or retinal vein occlusion, and critically ill patients.

Safety and Acceptability of a Natural Language Artificial Intelligence Assistant to Deliver Clinical Follow-up to Cataract Surgery Patients: Proposal

Background

Due to an aging population, the demand for many services is exceeding the capacity of the clinical workforce. As a result, staff are facing a crisis of burnout from being pressured to deliver high-volume workloads, driving increasing costs for providers. Artificial intelligence (AI), in the form of conversational agents, presents a possible opportunity to enable efficiency in the delivery of care.

Objective

This study aims to evaluate the effectiveness, usability, and acceptability of Dora agent: Ufonia’s autonomous voice conversational agent, an AI-enabled autonomous telemedicine call for the detection of postoperative cataract surgery patients who require further assessment. The objectives of this study are to establish Dora’s efficacy in comparison with an expert clinician, determine baseline sensitivity and specificity for the detection of true complications, evaluate patient acceptability, collect evidence for cost-effectiveness, and capture data to support further development and evaluation.

Methods

Using an implementation science construct, the interdisciplinary study will be a mixed methods phase 1 pilot establishing interobserver reliability of the system, usability, and acceptability. This will be done using the following scales and frameworks: the system usability scale; assessment of Health Information Technology Interventions in Evidence-Based Medicine Evaluation Framework; the telehealth usability questionnaire; and the Non-Adoption, Abandonment, and Challenges to the Scale-up, Spread and Suitability framework.

Results

The evaluation is expected to show that conversational technology can be used to conduct an accurate assessment and that it is acceptable to different populations with different backgrounds. In addition, the results will demonstrate how successfully the system can be delivered in organizations with different clinical pathways and how it can be integrated with their existing platforms.

Conclusions

The project’s key contributions will be evidence of the effectiveness of AI voice conversational agents and their associated usability and acceptability.

International Registered Report Identifier (IRRID)

PRR1-10.2196/27227

The Effectiveness of Artificial Intelligence Conversational Agents in Health Care: Systematic Review

Background

The high demand for health care services and the growing capability of artificial intelligence have led to the development of conversational agents designed to support a variety of health-related activities, including behavior change, treatment support, health monitoring, training, triage, and screening support. Automation of these tasks could free clinicians to focus on more complex work and increase the accessibility to health care services for the public. An overarching assessment of the acceptability, usability, and effectiveness of these agents in health care is needed to collate the evidence so that future development can target areas for improvement and potential for sustainable adoption.

Objective

This systematic review aims to assess the effectiveness and usability of conversational agents in health care and identify the elements that users like and dislike to inform future research and development of these agents.

Methods

PubMed, Medline (Ovid), EMBASE (Excerpta Medica dataBASE), CINAHL (Cumulative Index to Nursing and Allied Health Literature), Web of Science, and the Association for Computing Machinery Digital Library were systematically searched for articles published since 2008 that evaluated unconstrained natural language processing conversational agents used in health care. EndNote (version X9, Clarivate Analytics) reference management software was used for initial screening, and full-text screening was conducted by 1 reviewer. Data were extracted, and the risk of bias was assessed by one reviewer and validated by another.

Results

A total of 31 studies were selected and included a variety of conversational agents, including 14 chatbots (2 of which were voice chatbots), 6 embodied conversational agents (3 of which were interactive voice response calls, virtual patients, and speech recognition screening systems), 1 contextual question-answering agent, and 1 voice recognition triage system. Overall, the evidence reported was mostly positive or mixed. Usability and satisfaction performed well (27/30 and 26/31), and positive or mixed effectiveness was found in three-quarters of the studies (23/30). However, there were several limitations of the agents highlighted in specific qualitative feedback.

Conclusions

The studies generally reported positive or mixed evidence for the effectiveness, usability, and satisfactoriness of the conversational agents investigated, but qualitative user perceptions were more mixed. The quality of many of the studies was limited, and improved study design and reporting are necessary to more accurately evaluate the usefulness of the agents in health care and identify key areas for improvement. Further research should also analyze the cost-effectiveness, privacy, and security of the agents.

International Registered Report Identifier (IRRID)

RR2-10.2196/16934

Micropulse transscleral cyclophotocoagulation: initial results using a reduced energy protocol in refractory glaucoma

PURPOSE

This study evaluates the 6-month safety and efficacy of micropulse transscleral cyclophotocoagulation (MP-TSCPC) in cases of uncontrolled glaucoma/ocular hypertension using a reduced energy protocol.

METHODS

Retrospective analysis of patients undergoing MP-TSCPC from January-April 2018 was carried out. Patients received up to 90 s of laser with settings of 2000 mW/Cm2 and a duty cycle of 31.3%.

RESULTS

A total of 29 patients were included, with a mean age of 64.7 ± 15.1 years. The most common diagnosis was primary open angle glaucoma (41.4%) with a mean Logmar visual acuity of 1.5 ± 1.2. All subjects had either undergone intraocular surgery (58.6% filtration surgery) or continuous wave diode laser prior to micropulse treatment. Mean pre-laser IOP was 26.2 ± 11.1 mmHg. There was a significant reduction (p < 0.05) in IOP at 1 month to 15.8 ± 5.4 mmHg (39.7% reduction), at 3 months to 15.04 ± 5.25 mmHg (42.6% reduction) and at 6 months to 18.19 ± 7.47 mmHg (30.6% reduction). There was also a corresponding reduction (p < 0.05) in the number of topical agents required to control pressure from a baseline of 3.31 ± 0.97, to 2.72 ± 0.88 at 1 month, 2.76 ± 0.91 at 3 months and 2.90 ± 1.08 at 6 months. Requirements for oral acetazolamide reduced from 41.3% (1/29) at baseline to 3.4% (1/29) at 6 months. Success rates were 75.9% at 1 month, 79.3% at 3 months and 58.6% at 6 months. There was no drop in the visual acuity, no change in central retinal thickness and no cases of intraocular inflammation.

CONCLUSIONS

MP-TSCPC at a decreased duration is effective at reducing intraocular pressure in ethnically diverse glaucoma patients refractory to previous glaucoma laser or surgeries at 6 months follow-up, with no significant complications. Further work is needed to confirm efficacy in the long term and to determine optimal settings.

A semi-automated technique for labeling and counting of apoptosing retinal cells

BACKGROUND

Retinal ganglion cell (RGC) loss is one of the earliest and most important cellular changes in glaucoma. The DARC (Detection of Apoptosing Retinal Cells) technology enables in vivo real-time non-invasive imaging of single apoptosing retinal cells in animal models of glaucoma and Alzheimer's disease. To date, apoptosing RGCs imaged using DARC have been counted manually. This is time-consuming, labour-intensive, vulnerable to bias, and has considerable inter- and intra-operator variability.

RESULTS

A semi-automated algorithm was developed which enabled automated identification of apoptosing RGCs labeled with fluorescent Annexin-5 on DARC images. Automated analysis included a pre-processing stage involving local-luminance and local-contrast "gain control", a "blob analysis" step to differentiate between cells, vessels and noise, and a method to exclude non-cell structures using specific combined 'size' and 'aspect' ratio criteria. Apoptosing retinal cells were counted by 3 masked operators, generating 'Gold-standard' mean manual cell counts, and were also counted using the newly developed automated algorithm. Comparison between automated cell counts and the mean manual cell counts on 66 DARC images showed significant correlation between the two methods (Pearson's correlation coefficient 0.978 (p < 0.001), R Squared = 0.956. The Intraclass correlation coefficient was 0.986 (95% CI 0.977-0.991, p < 0.001), and Cronbach's alpha measure of consistency = 0.986, confirming excellent correlation and consistency. No significant difference (p = 0.922, 95% CI: -5.53 to 6.10) was detected between the cell counts of the two methods.

CONCLUSIONS

The novel automated algorithm enabled accurate quantification of apoptosing RGCs that is highly comparable to manual counting, and appears to minimise operator-bias, whilst being both fast and reproducible. This may prove to be a valuable method of quantifying apoptosing retinal cells, with particular relevance to translation in the clinic, where a Phase I clinical trial of DARC in glaucoma patients is due to start shortly.

Unexpected low-dose toxicity of the universal solvent DMSO

Dimethyl sulfoxide (DMSO) is an important aprotic solvent that can solubilize a wide variety of otherwise poorly soluble polar and nonpolar molecules. This, coupled with its apparent low toxicity at concentrations <10%, has led to its ubiquitous use and widespread application. Here, we demonstrate that DMSO induces retinal apoptosis in vivo at low concentrations (5 μl intravitreally dosed DMSO in rat from a stock concentration of 1, 2, 4, and 8% v/v). Toxicity was confirmed in vitro in a retinal neuronal cell line, at DMSO concentrations >1% (v/v), using annexin V, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and AlamarBlue cell viability assays. DMSO concentrations >10% (v/v) have recently been reported to cause cellular toxicity through plasma membrane pore formation. Here, we show the mechanism by which low concentrations (2-4% DMSO) induce caspase-3 independent neuronal death that involves apoptosis-inducing factor (AIF) translocation from mitochondria to the nucleus and poly-(ADP-ribose)-polymerase (PARP) activation. These results highlight safety concerns of using low concentrations of DMSO as a solvent for in vivo administration and in biological assays. We recommend that methods other than DMSO are employed for solubilizing drugs but, where no alternative exists, researchers compute absolute DMSO final concentrations and include an untreated control group in addition to DMSO vehicle control to check for solvent toxicity.