Physical and Psychosocial Challenges as Predictors of Vision Difficulty in Children: A Nationally Representative Survey Analysis.

PURPOSE: To elicit associations between vision difficulties and physical or psychosocial challenges in children in the United States. METHODS: Children aged 2-17 years old from the 2021 National Health Interview Survey with data pertaining to vision difficulty were included in our retrospective, population-based analysis. Our primary aim was investigating physical and psychosocial challenges as predictors of vision difficulty. Logistic regression models were performed on Stata version 17.0 (StataCorp LLC, College Station, Texas). Analyses were accompanied by an odds ratio (OR) and 95% confidence interval (CI). RESULTS: A total of 7,373 children had data pertaining to their level of vision difficulty and were included in our sample. In our multivariable analysis, children with a good/fair (OR = 1.84, 95% CI = [1.31, 2.60], p < 0.01), or poor (OR = 5.08, 95% CI = [1.61, 16.04], p < 0.01) general health status had higher odds of vision difficulty relative to children with an excellent/very good health status. Furthermore, children with difficulties hearing (OR = 8.67, 95% CI = [5.25, 14.31], p < 0.01), communicating (OR = 1.96, 95% CI = [1.18, 3.25], p < 0.01), learning (OR = 1.93, 95% CI = [1.27, 2.93], p < 0.01), and making friends (OR = 1.94, 95% CI = [1.12, 3.36], p = 0.02) had higher odds of vision difficulty. Nonetheless, the following factors were only predictors of vision difficulty in our univariable analysis: requiring equipment for mobility (p < 0.01), experiencing anxiety (p < 0.01), and experiencing depression (p < 0.01). CONCLUSION: Several factors pertaining to physical and psychosocial challenges in children are associated with vision difficulty. Future research should further explore potential causal links between vision difficulty and physical or psychosocial factors to aid in coordinating public health efforts dedicated to vision health equity.

The Association Between Retinal Thickness Fluctuations and Visual Outcomes Under Anti-VEGF Therapy: A Systematic Review and Meta-Analysis.

INTRODUCTION: To examine the association between retinal thickness (RT) fluctuations and best-corrected visual acuity (BCVA) in eyes with neovascular AMD, macular edema secondary to RVO, and DME treated with anti-VEGF therapy. METHODS: A systematic search of Ovid MEDLINE, EMBASE, and the Cochrane Library was performed from January 2006 to March 2024. Studies comparing visual or anatomic outcomes of patients treated with anti-VEGF therapy, stratified by magnitudes of RT fluctuation, were included. ROBINS-I and Cochrane RoB 2 tools were used to assess risk of bias, and certainty of evidence was evaluated with GRADE criteria. Meta-analysis was performed with a random effects model. Primary outcomes were final BCVA and change in BCVA relative to baseline. RESULTS: 15725 articles were screened; 15 studies were identified in the systematic review and 5 studies were included in the meta-analysis. Final ETDRS VA was significantly worse in eyes with the highest level of RT fluctuation (weighted mean difference (WMD) = 7.86 letters; 95% CI, 4.97, 10.74; p < 0.00001; I² = 81%; 3136 eyes). RT at last observation was significantly greater in eyes with high RT fluctuations (WMD = -27.35 µm; 95% CI, -0.04, 54.75; p = 0.05; I2 = 88%; 962 eyes). CONCLUSIONS: Final visual outcome is associated with magnitude of RT fluctuation over the course of therapy. It is unclear whether minimizing RT fluctuations would help to optimize visual outcomes in patients treated with anti-VEGF therapy. These findings are limited by a small set of studies, risk of bias, and considerable heterogeneity.

Pars Plana Vitrectomy With Silicone Oil or Gas Tamponade for Uncomplicated Retinal Detachment: A Systematic Review and Meta-Analysis.

PURPOSE: To compare the efficacy and safety of pars plana vitrectomy (PPV) with silicone oil compared to gas tamponade for uncomplicated rhegmatogenous retinal detachment (RRD). DESIGN: Systematic review and meta-analysis. METHODS: A systematic literature search was conducted on Ovid MEDLINE, Embase, and the Cochrane Library from January 2000 to September 2023 for comparative studies evaluating the efficacy and safety of PPV with either silicone oil or gas tamponade in the setting of uncomplicated RRD. Our primary outcome was best-corrected visual acuity at the last study observation. Secondary outcomes included the rates of retinal reattachment, retinal thickness, and the incidence of adverse events. We performed a meta-analysis using a random-effects model. RESULTS: Nine observational studies reporting on 491 RRD eyes were included. The mean best-corrected visual acuity at the last study observation was significantly better in the gas tamponade group than in the silicone oil group (weighted mean difference [WMD] = 0.17 logMAR, 95% confidence interval [CI] = [0.06, 0.27], P = .002). Rates of primary retinal reattachment were similar between the silicone oil and gas tamponade groups (P = .89). The ganglion cell layer was significantly thinner in the silicone oil group compared to the gas tamponade group (WMD =-3.70 µm, 95% CI = [-5.87, -1.53, P = .0008), as was the inner plexiform layer (WMD = -2.45, 95% CI = [-4.50, -0.40], P = .02) and outer nuclear layer (WMD = -11.74 µm, 95% CI = [-18.39, -5.10], P = .0005). CONCLUSIONS: PPV with gas tamponade was associated with better functional outcomes compared to PPV with silicone oil, although both tamponades yielded comparable primary reattachment rates. The absence of randomized trials and the potential for selection bias underscore the importance of further investigation in diverse patient populations.

Google Gemini and Bard artificial intelligence chatbot performance in ophthalmology knowledge assessment.

PURPOSE: With the popularization of ChatGPT (Open AI, San Francisco, California, United States) in recent months, understanding the potential of artificial intelligence (AI) chatbots in a medical context is important. Our study aims to evaluate Google Gemini and Bard's (Google, Mountain View, California, United States) knowledge in ophthalmology. METHODS: In this study, we evaluated Google Gemini and Bard's performance on EyeQuiz, a platform containing ophthalmology board certification examination practice questions, when used from the United States (US). Accuracy, response length, response time, and provision of explanations were evaluated. Subspecialty-specific performance was noted. A secondary analysis was conducted using Bard from Vietnam, and Gemini from Vietnam, Brazil, and the Netherlands. RESULTS: Overall, Google Gemini and Bard both had accuracies of 71% across 150 text-based multiple-choice questions. The secondary analysis revealed an accuracy of 67% using Bard from Vietnam, with 32 questions (21%) answered differently than when using Bard from the US. Moreover, the Vietnam version of Gemini achieved an accuracy of 74%, with 23 (15%) answered differently than the US version of Gemini. While the Brazil (68%) and Netherlands (65%) versions of Gemini performed slightly worse than the US version, differences in performance across the various country-specific versions of Bard and Gemini were not statistically significant. CONCLUSION: Google Gemini and Bard had an acceptable performance in responding to ophthalmology board examination practice questions. Subtle variability was noted in the performance of the chatbots across different countries. The chatbots also tended to provide a confident explanation even when providing an incorrect answer.

Dose-response of localized renal cell carcinoma after stereotactic body radiation therapy: A meta-analysis.

BACKGROUND: Stereotactic ablative radiation therapy (SBRT) is an emerging treatment option for primary renal cell carcinoma (RCC), particularly in patients who are unsuitable for surgery. The aim of this review is to assess the effect of increasing the biologically equivalent dose (BED) via various radiation fractionation regimens on clinical outcomes. METHODS: A literature search was conducted in PubMed (Medline), EMBASE, and the Cochrane Library for studies published up to October 2023. Studies reporting on patients with localized RCC receiving SBRT were included to determine its effectiveness on local control, progression-free survival, and overall survival. A random effects model was used to meta-regress clinical outcomes relative to the BED for each study and heterogeneity was assessed by I2. RESULTS: A total of 724 patients with RCC from 22 studies were included, with a mean age of 72.7 years (range: 44.0-81.0). Local control was excellent with an estimate of 99 % (95 %CI: 97-100 %, I2 = 19 %), 98 % (95 %CI: 96-99 %, I2 = 8 %), and 94 % (95 %CI: 90-97 %, I2 = 11 %) at one year, two years, and five years respectively. No definitive association between increasing BED and local control, progression-free survival and overall survival was observed. No publication bias was observed. CONCLUSIONS: A significant dose response relationship between oncological outcomes and was not identified, and excellent local control outcomes were observed at the full range of doses. Until new evidence points otherwise, we support current recommendations against routine dose escalation beyond 25-26 Gy in one fraction or 42-48 Gy in three fractions, and to consider de-escalation or compromising target coverage if required to achieve safe organ at risk doses.

Accuracy of an Artificial Intelligence Chatbot's Interpretation of Clinical Ophthalmic Images.

Importance: Ophthalmology is reliant on effective interpretation of multimodal imaging to ensure diagnostic accuracy. The new ability of ChatGPT-4 (OpenAI) to interpret ophthalmic images has not yet been explored. Objective: To evaluate the performance of the novel release of an artificial intelligence chatbot that is capable of processing imaging data. Design, Setting, and Participants: This cross-sectional study used a publicly available dataset of ophthalmic cases from OCTCases, a medical education platform based out of the Department of Ophthalmology and Vision Sciences at the University of Toronto, with accompanying clinical multimodal imaging and multiple-choice questions. Across 137 available cases, 136 contained multiple-choice questions (99%). Exposures: The chatbot answered questions requiring multimodal input from October 16 to October 23, 2023. Main Outcomes and Measures: The primary outcome was the accuracy of the chatbot in answering multiple-choice questions pertaining to image recognition in ophthalmic cases, measured as the proportion of correct responses. χ2 Tests were conducted to compare the proportion of correct responses across different ophthalmic subspecialties. Results: A total of 429 multiple-choice questions from 136 ophthalmic cases and 448 images were included in the analysis. The chatbot answered 299 of multiple-choice questions correctly across all cases (70%). The chatbot's performance was better on retina questions than neuro-ophthalmology questions (77% vs 58%; difference = 18%; 95% CI, 7.5%-29.4%; χ21 = 11.4; P < .001). The chatbot achieved a better performance on nonimage-based questions compared with image-based questions (82% vs 65%; difference = 17%; 95% CI, 7.8%-25.1%; χ21 = 12.2; P < .001).The chatbot performed best on questions in the retina category (77% correct) and poorest in the neuro-ophthalmology category (58% correct). The chatbot demonstrated intermediate performance on questions from the ocular oncology (72% correct), pediatric ophthalmology (68% correct), uveitis (67% correct), and glaucoma (61% correct) categories. Conclusions and Relevance: In this study, the recent version of the chatbot accurately responded to approximately two-thirds of multiple-choice questions pertaining to ophthalmic cases based on imaging interpretation. The multimodal chatbot performed better on questions that did not rely on the interpretation of imaging modalities. As the use of multimodal chatbots becomes increasingly widespread, it is imperative to stress their appropriate integration within medical contexts.

PARS PLANA VITRECTOMY WITH OR WITHOUT INTERNAL LIMITING MEMBRANE PEEL FOR MACULAR HOLE: A Systematic Review and Meta-Analysis.

PURPOSE: To compare the efficacy and safety of pars plana vitrectomy with and without internal limiting membrane (ILM) peeling for macular hole (MH). METHODS: A systematic literature search on Ovid MEDLINE, Embase, Cochrane Library, and Google Scholar was performed from January 2000 to 2023. The primary outcome was the final best-corrected visual acuity (BCVA). Secondary outcomes included MH closure rates and the need for repeat surgery. The authors performed a random-effects meta-analysis on Review Manager 5.4. RESULTS: Fourteen studies on 880 eyes were included. Pars plana vitrectomy with and without ILM peel achieved a similar final BCVA ( P = 0.66). However, pars plana vitrectomy without ILM peeling achieved a significantly better final BCVA in eyes with closed MHs (WMD = 0.05 logMAR, 95% CI, 0.01-0.10, P = 0.02). Pars plana vitrectomy with ILM peeling achieved a significantly higher primary MH closure rate (RR = 1.21, 95% CI, 1.04-1.42, P = 0.02) and lower incidence of MH reoperation (RR = 0.19, 95% CI, 0.11-0.33, P < 0.001). The final MH closure rate ( P = 0.12) and incidence of MH recurrence ( P = 0.25) were similar between groups. CONCLUSION: Pars plana vitrectomy with and without ILM peel achieved a similar final BCVA. However, pars plana vitrectomy without ILM peeling achieved a better final BCVA in eyes with closed MHs. ILM peeling achieved a greater primary MH closure rate and reduced need for reoperation.

Diagnostic methods for primary vitreoretinal lymphoma: A systematic review.

Primary vitreoretinal lymphoma is a potentially aggressive intraocular malignancy with poor systemic prognosis and sometimes significant diagnostic delays as it may masquerade as chronic uveitis. Despite the variety of diagnostic techniques, it is unclear which modality is most accurate in the diagnosis of PVRL. A systematic literature search was conducted on Ovid MEDLINE, EMBASE and the Cochrane Controlled Register of Trials for studies published between January, 2000, and June, 2023. Randomized controlled trials (RCTs) reporting on the following diagnostic tools used to diagnose patients with PVRL were included: cytology, flow cytometry, MYD88 L265P mutation, CD79B mutation, interleukin 10/interleukin-6 (IL-10/IL-6) ratio, polymerase chain reaction (PCR) for monoclonal immunoglobulin heavy chain (IgH) and immunoglobulin kappa light chain (IgK) rearrangements, and imaging findings. The aggregated sensitivity of each diagnostic modality was reported and compared using the chi-squared (χ2) test. A total of 662 eyes from 29 retrospective studies reporting on patients diagnosed with PVRL were included. An IL-10/IL-6 ratio greater than 1 had the highest sensitivity (89.39%, n = 278/311 eyes, n = 16 studies) for PVRL, where the sensitivity was not significantly different when only vitreous samples were drawn (88.89%, n = 232/261 eyes, n = 13 studies) compared to aqueous samples (83.33%, n = 20/24, n = 2) (p = 0.42). Flow cytometry of vitreous samples gave a positive result in 66/75 eyes (88.00%, n = 6 studies) with PVRL, and monoclonal IgH rearrangements on PCR gave a positive result in 354/416 eyes (85.10%, n = 20 studies) with PVRL. MYD88 L265P and CD79B mutation analysis performed poorly, yielding a positive result in 63/90 eyes (70.00%, n = 8 studies) with PVRL, and 20/57 eyes (35.09%, n = 4 studies) with PVRL, respectively. Overall, our systematic review found that an IL-10/IL-6 ratio greater or equal to one may provide the highest sensitivity in identifying patients with PVRL. Future studies are needed to employ multiple diagnostic tools to aid in the detection of PVRL and to further establish nuanced guidelines when determining the optimal diagnostic tool to use in diverse patient populations.

Cleft lip and/or palate mortality trends in the USA: a retrospective population-based study.

BACKGROUND: Cleft lip and/or palate (CL/P) is one of the most common congenital anomalies worldwide. Although CL/P management may require a series of interventions, mortality resulting from CL/P alone is rare. This study aims to examine recent trends of CL/P mortality rates in the USA. METHODS: A retrospective population-based study was conducted using official US birth and death certificate data from the Centers for Disease Control and Prevention from 2000 to 2019. Annual mortality rates per 1000 births with CL/P were calculated across sex and racial groups. Multivariable logistic regression models estimated the effects of sex and race on the risk of mortality with CL/P, and linear regression models were used to examine temporal changes in mortality rate across sex and race. RESULTS: From 2000 to 2019, 1119 deaths occurred in patients with documented CL/P, for an overall incidence of 20.3 deaths per 1000 births with CL/P (95% CI 18.9 to 22.8). Of these, Patau syndrome was the listed cause of death in 167 cases (14.9%). Black individuals (OR 1.93, 95% CI 1.85 to 2.01), Hispanic (1.54, 1.49 to 1.58) and American Indian individuals (1.28, 1.20 to 1.35) were at a greater risk of CL/P mortality compared with white individuals. Additionally, females were also at a greater risk (1.35, 1.21 to 1.49). A significant upward trend in CL/P mortality was observed in Hispanic (r2=0.70, p<0.01) and American Indian individuals (r2=0.81, p<0.01) from 2000 to 2019. CONCLUSIONS: Cleft birth and mortality surveillance is essential in healthcare and prevention planning. Future studies are required to understand the differences in CL/P mortality rates across various sociodemographic groups.

Systemic Arterial and Venous Thrombotic Events Associated With Anti-Vascular Endothelial Growth Factor Injections: A Meta-Analysis.

PURPOSE: To compare the risk of systemic arteriovenous thrombotic events between intravitreal anti-vascular endothelial growth factor (anti-VEGF) and sham injections. DESIGN: Random-effects meta-analysis. METHODS: A systematic search was performed on OVID MEDLINE, Embase, and Cochrane Library from January 2005 to August 2023. Our inclusion criteria were randomized controlled trials (RCTs) reporting on systemic arteriovenous events for standard dose intravitreal anti-VEGF agents for any indication. RESULTS: A total of 20 RCTs reporting on 12,833 eyes were included. There was no significant difference in the risk of any thrombotic event between bevacizumab 1.25 mg and ranibizumab 0.5 mg (Risk ratio (RR) = 0.96, 95% CI = 0.52-1.75, P = .89). There was no significant difference between bevacizumab and ranibizumab when restricting to arterial thrombotic events (RR= 0.88, 95% CI = 0.60-1.30, P = .53) or venous thrombotic events (RR = 1.99, 95% CI =86 0.68-5.82], P = .21). The risk of arterial thrombotic events was similar between aflibercept and bevacizumab (RR = 1.11, 95% CI = 0.60-2.07, P = .74), between aflibercept and ranibizumab (RR= 0.77, 95% CI = 0.49-1.21, P = .26), between brolucizumab and aflibercept (RR= 0.67, 95% CI = 0.32-1.38, P = .27), and between aflibercept and faricimab (RR = 0.96, 95% CI = 0.43-2.17, P = .93). Compared to sham, neither dose of ranibizumab (0.5 mg or 0.3 mg) showed a higher risk of arterial thrombotic events. CONCLUSIONS: There was a similar risk of systemic arteriovenous thrombotic adverse events between anti-VEGF agents and between ranibizumab and sham injections.

THE ABILITY OF ARTIFICIAL INTELLIGENCE CHATBOTS ChatGPT AND GOOGLE BARD TO ACCURATELY CONVEY PREOPERATIVE INFORMATION FOR PATIENTS UNDERGOING OPHTHALMIC SURGERIES.

INTRODUCTION: To determine whether the two popular artificial intelligence chatbots, ChatGPT and Bard, can provide high-quality information concerning procedure description, risks, benefits, and alternatives of various ophthalmic surgeries. METHODS: ChatGPT and Bard were prompted with questions pertaining to the description, potential risks, benefits, alternatives, and implications of not proceeding with various surgeries in different subspecialties of ophthalmology. Six common ophthalmic procedures were included in the authors' analysis. Two comprehensive ophthalmologists and one subspecialist graded each response independently using a 5-point Likert scale. RESULTS: Likert grading for accuracy was significantly higher for ChatGPT in comparison with Bard (4.5 ± 0.6 vs. 3.8 ± 0.8, P < 0.0001). Generally, ChatGPT performed better than Bard even when questions were stratified by the type of ophthalmic surgery. There was no significant difference between ChatGPT and Bard for response length (2,104.7 ± 271.4 characters vs. 2,441.0 ± 633.9 characters, P = 0.12). ChatGPT responded significantly slower than Bard (46.0 ± 3.0 vs. 6.6 ± 1.2 seconds, P < 0.0001). CONCLUSION: Both ChatGPT and Bard may offer accessible and high-quality information relevant to the informed consent process for various ophthalmic procedures. Nonetheless, both artificial intelligence chatbots overlooked the probability of adverse events, hence limiting their potential and introducing patients to information that may be difficult to interpret.

Intravitreal Triamcinolone Acetonide for Diabetic Macular Edema and Macular Edema Secondary to Retinal Vein Occlusion: A Meta-Analysis.

BACKGROUND: The comparative safety and efficacy of different doses of intravitreal triamcinolone acetonide (IVTA) for diabetic macular edema (DME) and macular edema (ME) secondary to retinal vein occlusion (RVO) is unclear. OBJECTIVES: This meta-analysis aimed to compare the safety and efficacy of different doses of IVTA in this setting. METHODS: A systematic literature search for randomized clinical trials (RCTs) was conducted on Cochrane Library, Ovid MEDLINE, and EMBASE from January 2005 to May 2022. Studies that reported on patients with DME or ME secondary to RVO that received treatment with different doses of IVTA were included. A random-effects meta-analysis was performed. Cochrane's Risk of Bias Tool 2 was used to assess the risk of bias, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) guidelines were used to assess certainty of evidence. RESULTS: Five RCTs reporting on 1,041 eyes at baseline were included in this meta-analysis. In eyes with ME secondary to RVO, high-dose (4 mg) IVTA achieved a significantly better change in best-corrected visual acuity (WMD = -4.75 ETDRS letters, 95% CI = [-7.73, -1.78], p = 0.002) and reduction in retinal thickness (WMD = -93.02 µm, 95% CI = [-153.23, -32.82], p = 0.002) at months 4-6 compared to low-dose (1-2 mg) IVTA. However, high-dose IVTA had a higher risk of intraocular pressure-related adverse events (RR = 2.99, 95% CI = [1.05, 8.50], p = 0.04) and cataract surgery (RR = 5.67, 95% CI = [3.09, 10.41], p < 0.00001) than low-dose IVTA in eyes with ME secondary to RVO. These efficacy and safety differences in high-dose and low-dose IVTA were not observed in DME eyes. CONCLUSIONS: The RCT evidence in this setting is limited. High-dose IVTA achieved greater improvements in visual acuity and reductions in retinal thickness than low-dose IVTA at months 4-6. However, high-dose IVTA had a less favorable safety profile than low-dose IVTA. The significance of these outcomes was based on patients with ME secondary to RVO, but not DME.

ASSOCIATION OF INTRAVENOUS FLUORESCEIN ANGIOGRAPHY AND ADAPTIVE OPTICS IMAGING IN DIABETIC RETINOPATHY: A Prospective Case Series.

PURPOSE: To our knowledge, we present the first case series investigating the relationship between adaptive optics (AO) imaging and intravenous fluorescein angiography (IVFA) parameters in patients with diabetic retinopathy. METHODS: Consecutive patients with diabetic retinopathy older than age 18 years presenting to a single center in Toronto, Canada, from 2020 to 2021 were recruited. Adaptive optics was performed with the RTX1 camera (Imagine Eyes, Orsay, France) at retinal eccentricities of 2° and 4°. Intravenous fluorescein angiography was assessed with the artificial intelligence-based RETICAD system to extract blood flow, perfusion, and blood-retinal-barrier (BRB) permeability at the same retinal locations. Correlations between AO and IVFA parameters were calculated using Pearson's correlation coefficient. RESULTS: Across nine cases, a significant positive correlation existed between photoreceptor spacing on AO and BRB permeability (r = 0.303, P = 0.027), as well as perfusion (r = 0.272, P = 0.049) on IVFA. When stratified by location, a significant positive correlation between photoreceptor dispersion and both BRB permeability and perfusion (r = 0.770, P = 0.043; r = 0.846, P = 0.034, respectively) was observed. Cone density was also negatively correlated with BRB permeability (r = -0.819, P = 0.046). CONCLUSION: Photoreceptor spacing on AO was significantly correlated with BRB permeability and perfusion on IVFA in patients with diabetic retinopathy. Future studies with larger sample sizes are needed to understand the relationship between AO and IVFA parameters in diverse patient populations.

ChatGPT-4: An assessment of an upgraded artificial intelligence chatbot in the United States Medical Licensing Examination.

PURPOSE: ChatGPT-4 is an upgraded version of an artificial intelligence chatbot. The performance of ChatGPT-4 on the United States Medical Licensing Examination (USMLE) has not been independently characterized. We aimed to assess the performance of ChatGPT-4 at responding to USMLE Step 1, Step 2CK, and Step 3 practice questions. METHOD: Practice multiple-choice questions for the USMLE Step 1, Step 2CK, and Step 3 were compiled. Of 376 available questions, 319 (85%) were analyzed by ChatGPT-4 on March 21st, 2023. Our primary outcome was the performance of ChatGPT-4 for the practice USMLE Step 1, Step 2CK, and Step 3 examinations, measured as the proportion of multiple-choice questions answered correctly. Our secondary outcomes were the mean length of questions and responses provided by ChatGPT-4. RESULTS: ChatGPT-4 responded to 319 text-based multiple-choice questions from USMLE practice test material. ChatGPT-4 answered 82 of 93 (88%) questions correctly on USMLE Step 1, 91 of 106 (86%) on Step 2CK, and 108 of 120 (90%) on Step 3. ChatGPT-4 provided explanations for all questions. ChatGPT-4 spent 30.8 ± 11.8 s on average responding to practice questions for USMLE Step 1, 23.0 ± 9.4 s per question for Step 2CK, and 23.1 ± 8.3 s per question for Step 3. The mean length of practice USMLE multiple-choice questions that were answered correctly and incorrectly by ChatGPT-4 was similar (difference = 17.48 characters, SE = 59.75, 95%CI = [-100.09,135.04], t = 0.29, p = 0.77). The mean length of ChatGPT-4's correct responses to practice questions was significantly shorter than the mean length of incorrect responses (difference = 79.58 characters, SE = 35.42, 95%CI = [9.89,149.28], t = 2.25, p = 0.03). CONCLUSIONS: ChatGPT-4 answered a remarkably high proportion of practice questions correctly for USMLE examinations. ChatGPT-4 performed substantially better at USMLE practice questions than previous models of the same AI chatbot.