Multi-center validation of Catquest-9SF visual function questionnaire in Ontario, Canada.

PURPOSE: To investigate the psychometric performance and responsiveness of Catquest-9SF, a patient-reported questionnaire developed to evaluate visual function as related to daily tasks, in patients referred for cataract surgery in Ontario, Canada. METHODS: This is a pooled analysis on prospective data collected for previous projects. Subjects were recruited from three tertiary care centers in Peel region, Hamilton, and Toronto, Ontario, Canada. Catquest-9SF was administered pre-operative and post-operatively to patients with cataract. Psychometric properties, including category threshold order, infit/outfit, precision, unidimensionality, targeting, and differential item functioning were tested using Rasch analysis with Winsteps software (v.4.4.4) for Catquest-9SF. Responsiveness of questionnaire scores to cataract surgery was assessed. RESULTS: 934 patients (mean age = 71.6, 492[52.7%] female) completed the pre- and post-operative Catquest-9SF questionnaire. Catquest-9SF had ordered response thresholds, adequate precision (person separation index = 2.01, person reliability = 0.80), and confirmed unidimensionality. The infit range was 0.75-1.29 and the outfit range was 0.74-1.51, with one item ('satisfaction with vision') misfitting (outfit value = 1.51). There was mistargeting of -1.07 in pre-operative scores and mistargeting of -2.43 in both pre- and post-operative scores, meaning that tasks were relatively easy for respondent ability. There was no adverse differential item functioning. There was a mean 1.47 logit improvement in Catquest-9SF scores after cataract surgery (p<0.001). CONCLUSION: Catquest-9SF is a psychometrically robust questionnaire for assessment of visual function in patients with cataract in Ontario, Canada. It is also responsive to clinical improvement after cataract surgery.

A retrospective population-based analysis of wait times for cataract surgery in Ontario, Canada.

BACKGROUND: Current methods used to estimate surgical wait times in Ontario may be subject to inconsistencies and inaccuracies. In this population-level study, we aimed to estimate cataract surgery wait times in Ontario using a novel, objective and data-driven method. METHODS: We identified adults who underwent cataract surgery between 2005 and 2019 in Ontario, using administrative records. Wait time 1 represented the number of days from referral to initial visit with the surgeon, and wait time 2 represented the number of days from the decision for surgery until the first eye surgery date. In the primary analysis, a ranking method prioritized referrals from optometrists, followed by ophthalmologists and family physicians. RESULTS: The cohort consisted of 1 138 532 people with mostly female patients (57.4%) and those aged 65 years and older (79.0%). In the primary analysis, the median was 67 days for wait time 1 (interquartile range [IQR] 29-147). There was a median of 77 days for wait time 2 (IQR 37-155). Overall, the following proportions of patients waited less than 3, 6 and 12 months: 54.1%, 78.5% and 91.7%, respectively. For wait time 2, the proportions of patients who waited less than 3, 6 and 12 months were 49.5%, 77.1% and 93.3%, respectively. In total, 19.3% of patients did not meet the provincial target for wait time 1, 20.5% did not meet the target for wait time 2 and 35.0% did not meet the target for wait times 1 or 2. INTERPRETATION: Administrative health services data can be used to estimate cataract surgery wait times. With this method, 35.0% of patients in 2005-2019 did not receive initial consultation or surgery within the provincial wait time target.

Preoperative evaluations for ophthalmic surgery: A systematic review of 48,869 eyes.

Eliminating low-yield testing can reduce the burden on modern health care systems. Our purpose is to determine whether routine preoperative assessment impacts the incidence of perioperative complications in ophthalmic surgery. We conducted a comprehensive search of Ovid MEDLINE, EMBASE, and Cochrane Library databases to identify studies investigating the incidence of perioperative complications following any preoperative assessment for patients undergoing ophthalmic surgery (PROSPERO ID#164008). Four randomized controlled trials (RCTs) and 5 observational studies were selected for inclusion. Risk of bias assessment revealed a lack of masking and insufficient statistical power in RCTs, and confounding in observational studies. Routine preoperative testing-including laboratory tests, electrocardiogram, and imaging studiesdid not decrease the incidence of adverse events or risk of perioperative ocular and systemic complications in most studies. Two cohort studies (1 retrospective, 1 prospective) suggestd that patients with certain preexisting health conditions were at increased risk for adverse events perioperatively. Another retrospective study found a lower risk of complications in high-risk patients who underwent evaluation. While patients with comorbidities may be at increased risk of adverse events, the role of preoperative assessment is not well delineated in this population. Further study is required to determine the comparative safety, effectiveness, and implementation of alternative assessment tools.

Validation of a novel patient satisfaction questionnaire for preoperative fasting in cataract surgery: a discrimination analysis.

OBJECTIVE: Preoperative fasting is routinely performed to prevent anaesthesia-related pulmonary aspiration. To capture patients' experiences with preoperative fasting, a 13-item questionnaire was developed and validated using Rasch analysis and shortened to 6 items. This extension study aims to assess this questionnaire's ability to discriminate between participants with a short versus long duration of fasting and early versus late day surgery. DESIGN: Single-centred cross-sectional study. PARTICIPANTS: Subjects were recruited via consecutive sampling of cataract patients on surgery day at Kensington Eye Institute in Toronto from February to December 2019. METHODS: A validated preoperative fasting questionnaire was administered. Discriminative ability was assessed by comparing responses in patients scheduled for surgery in the morning (8:00 am-12:00 pm) versus afternoon (12:00 pm-3:30 pm) and fasting for short (≤8 hours) versus long (>8 hours) duration. Diagnostic ability of the 6-item questionnaire relative to the 13-item questionnaire was assessed with receiver operating characteristics curve analysis. RESULTS: A total of 164 patients (mean age 70.8 ± 10.0 years; 57% female) were included. Total scores of patients having surgery in the morning were greater (i.e., less fasting-related burden) than in the afternoon (p = 0.04). There was no significant difference in scores between patients fasting for a short versus long duration (p > 0.05). Receiver operating characteristics curve analysis showed excellent diagnostic ability of the 6-item questionnaire relative to the 13-item version (area under the curve = 0.964). CONCLUSION: The 6-item questionnaire for fasting-related burden has excellent discriminative ability between early versus late surgery patients. The time fasting while awake may be a more relevant predictor of fasting-related burden relative to the total duration of fasting.

Backlog in ophthalmic surgeries associated with the COVID-19 pandemic in Ontario 2020.

OBJECTIVE: To assess the volume of deferred ophthalmic surgeries in Ontario associated with the COVID-19 pandemic from March to December 2020 and suggest strategies and time required to clear the backlog. DESIGN: Cross-sectional study. PARTICIPANTS: Ontarians eligible for the Ontario Health Insurance Plan in 2017-2020. METHODS: Backlog and clearance time for ophthalmic surgeries associated with the COVID-19 pandemic were estimated from time-series forecasting models and queuing theory. RESULTS: From March 16 to December 31, 2020, the estimated ophthalmic surgical backlog needing operating rooms was 92,150 surgeries (95% prediction interval, 71,288-112,841). Roughly 90% of the delayed surgeries were cataract surgeries, and a concerning 4% were retinal detachment surgeries. Nearly half the provincial backlog (48%; 44,542 of 92,150) was in patients from the western health region. In addition, an estimated 23,755 (95% prediction interval, 14,656-32,497) anti-vascular endothelial growth factor injections were missed. Estimated provincial clearance time was 248 weeks (95% CI, 235-260) and 128 weeks (95% CI, 121-134) if 10% and 20% of operating room surgical capacity per week were added, respectively, based on the weekly ophthalmic surgical volume in 2019. CONCLUSIONS: Ontario data demonstrate that the magnitude of the ophthalmic surgical backlog in 2020 alone raises serious concerns for meeting the ophthalmic surgical needs of patients. As the pandemic continues, the accrued backlog size is likely to increase. Planning and actions are needed urgently to better manage the collateral impacts of the pandemic on the ophthalmic surgical backlog.

Ontario Cataract Quality Outcome Initiative: appropriateness and prioritization of cataract surgery.

OBJECTIVE: To explore the utility of the Catquest 9SF visual function (VF) questionnaire along with visual acuity (VA) for determining appropriateness and priority for cataract surgery. To evaluate the feasibility of administering the Catquest-9SF in a clinical setting using web-based electronic data capture and interpretation. DESIGN: Prospective multicentred interventional observational study. PARTICIPANTS: Subjects undergoing sequential cataract surgery in both eyes at 4 sites in Ontario. METHODS: We recorded best-corrected VA (BCVA) and VA with current correction (CCVA) in each eye and both eyes (OU) and Catquest-9SF responses on a tablet before and after cataract surgery. Linear regression models were employed to test for associations between VA and visual function (VF). RESULTS: Preoperative BCVA and CCVA in the worse eye were significant predictors of change in VF (p = 0.006 and p = 0.008, respectively); subjects with worse VA had a greater improvement in VF after surgery. There was a significant association between improvement in VF and improvement in CCVA OU (p = 0.001). Fourteen of 151 subjects (9%) had no improvement or worse VF scores after surgery. Within this group, 10 of 14 subjects had a preoperative score ≤-3, which is suggestive of minimal visual disability. Within this subset, 4 of 14 subjects (2.6%) had a preoperative BCVA of 20/30 or better in their worse eye. CONCLUSIONS: For patient groups with equal VA, the Catquest-9SF score can help determine priority for surgery. Web-based data capture and interpretation allow for efficient virtual assessments of VF. A BCVA in the worse eye of 20/30 or better combined with a Catquest-9SF score <-3 can be used as a guideline for lowest priority.

Eye protection following cataract surgery: a systematic review.

BACKGROUND: There is a high variability in the use of postoperative eye protection among ophthalmologists. Postoperative eye protection treatment modalities include an eye shield, an eye patch, an ocular bandage, and instant vision. The aim of this study was to review and compare the evidence on the various options for eye protection. METHODS: A systematic literature search was conducted, and original comparative articles that reported on subjective symptoms (e.g., foreign-body sensation, photophobia, tearing, and pain) and postoperative outcomes (e.g., tear film breakup time, best-corrected visual acuity, etc.) after usage of an eye protection method were included. RESULTS: Overall, 598 eyes across 8 articles were included. Included studies investigated ocular bandages (n = 6), eye patches (n = 4), instant vision (n = 2), and eye shields (n = 1) postoperatively. In 5 studies, patients receiving ocular bandages self-reported symptoms, including pain (n = 3), foreign-body sensation (n = 4), photophobia (n = 3), and tearing (n = 3), at a reduced or equivalent rate compared with other treatment modalities. With the ocular bandage, 3 studies reported increased tear film breakup time, and 1 study reported improvements in corneal wound healing compared with a control group. Two studies reported reduced tear film breakup time for the eye patch relative to the ocular bandage, and another study reported reduced tear film breakup time for instant vision compared with the eye patch. CONCLUSIONS: Patient-reported symptoms are acutely reduced for patients receiving an ocular bandage relative to instant vision following cataract surgery. Patients prefer receiving some form of postoperative protection as opposed to instant vision.

Prediction accuracy of intraoperative aberrometry compared with preoperative biometry formulae for intraocular lens power selection.

OBJECTIVE: To compare the accuracy of intraoperative wavefront aberrometry to preoperative biometry formulae for predicting intraocular lens power. DESIGN: Retrospective, consecutive case series. PARTICIPANTS: Eyes undergoing cataract extraction with at least 1 month of follow-up after surgery at an ambulatory surgical centre in Toronto. METHODS: Consecutive sample of 228 cataract extractions with monofocal, trifocal, or toric intraocular lens implantation from November 1, 2017, to December 31, 2019. The spherical equivalent was predicted preoperatively with Barrett Universal II, Hill-Radial Basis Function (RBF), SRK/T, Holladay I, Holladay II, Haigis, and HofferQ using biometry measurements and intraoperatively with wavefront aberrometry. The primary outcomes were mean prediction error and proportion of eyes with a spherical equivalent within 0.5 D of the refractive target at postoperative month 1. RESULTS: The analysis included 159 eyes with 52% females and a mean age of 69.4 years. Formulae with the lowest mean prediction error were Hill-RBF (0.32 D ± 0.02 D), Barrett Universal II (0.32 D ± 0.02 D), intraoperative aberrometry (0.32 D ± 0.02 D), SRK/T (0.33 D ± 0.02 D), Holladay II (0.34 D ± 0.03 D), Holladay I (0.35 D ± 0.02 D), Haigis (0.37 D ± 0.02 D), and HofferQ (0.42 D ± 0.02 D). There were no statistically significant differences between intraoperative aberrometry and the preoperative formulae. Formulae with the highest proportion of eyes within 0.5 D of the refractive target were intraoperative aberrometry (82%), Barrett Universal II (81%), Hill-RBF (80%), SRK/T (77%), Holladay II (76%), Holladay I (75%), Haigis (71%), and HofferQ (70%). CONCLUSIONS: Intraoperative aberrometry and modern preoperative biometry formulae are equally effective at reaching the refractive target. In normal eyes, intraoperative aberrometry does not appear to provide any additional benefit to modern prediction formulae.

Evolution of first-line glaucoma therapy, 2007-2018: a population-based analysis.

OBJECTIVE: To evaluate the long-term evolution of first-line glaucoma therapy (FLGT) initiated by ophthalmologists and optometrists. DESIGN: Retrospective population-based study using validated provincial health care databases. PARTICIPANTS: 194,759 Ontario residents, 66 years of age or older, who received FLGT between 2007 and 2018. METHODS: A total of 194,759 individuals from 12 annual cohorts were enrolled, and rates of first-line medical treatment (prostaglandin analogue [PGA], beta-blocker, alpha-2-agonist, and carbonic anhydrase inhibitor) and laser trabeculoplasty (LT) were calculated. Provider (ophthalmologist or optometrist) rates also were assessed. RESULTS: Across the entire study period, of the 194,759 enrolled individuals who received FLGT, 60.2% initially received medical treatment and 39.8% underwent LT. Approximately 94.6% were treated by ophthalmologists. PGA therapy was the most common therapy prior to 2010, whereupon LT became the most common FLGT. By 2015, LT exceeded the total of all medications as FLGT. The annual rate of initial medication prescriptions by optometrists rose to 101.4 per 100,000 population between 2011 and 2018. In 2018, PGA and non-PGA prescription rates by ophthalmologists were 2.6 and 5.0 times higher, respectively, than prescription rates by optometrists. CONCLUSION: LT therapy has become the most common FLGT for Ontario residents 66 years of age or older. PGAs remain the most frequently prescribed glaucoma medication. While ophthalmologists continue to provide the majority of FLGT, optometrists now provide a small but growing fraction of FLGT following the introduction of glaucoma medication prescribing privileges.

Use of virtual care in ophthalmology in Ontario, Canada in 2020 during the COVID-19 pandemic.

OBJECTIVE: To investigate the use and trends of virtual care in ophthalmology and examine associated factors in a universal health care system during the COVID-19 pandemic in 2020. DESIGN: Cross-sectional study. PARTICIPANTS: Ontarians eligible for the Ontario Health Insurance Plan. METHODS: We used physician billing data from 2017-2020 to describe the use of virtual versus in-person care. We used logistic regression to examine factors associated with virtual care use. RESULTS: The uptake of ophthalmic virtual visits increased immediately following the government's directive to ramp down clinic activities and institution of a new virtual fee code (17.6%), peaked 2 weeks later (55.8%), and decreased immediately after the directive was lifted (24.2%). In March-December 2020, virtual visits were higher in female (11.6%) versus male (10.3%) patients and in patients <20 years of age (16.4%) and 20-39 years of age (12.3%) versus those aged 40-64 years (10.8%) and 65+ years (10.6%). Patients residing in the poorest/poorer neighbourhoods (10.9%) had similar use as their counterparts (11.1%). Patients with an acute infectious disease (14.2%) or nonurgent diagnosis (16.2%) had the highest use. Those with retinal disease had the lowest use (4.2%). Female ophthalmologists (15.4%) provided virtual care more often than male ophthalmologists (9.9%). Ophthalmologists aged 60-69 years (13.1%) provided virtual care more often than any other age groups (<40 years: 11.3%; 40-49 years: 11.0%; 50-59 years: 10.0%; and 70+ years: 7.7%). Multiple logistic regression models revealed similar results. CONCLUSION: Virtual care in ophthalmology increased significantly during the initial phase of the pandemic and decreased thereafter. There were significant variations in virtual care use by patient and ophthalmologist characteristics.

Patient Satisfaction and Visual Function Following Implantation of Trifocal or Extended Range of Vision Intraocular Lenses.

Purpose: To compare the trifocal TFNT00 and extended depth-of-focus (EDF) ZXR00 intraocular lenses (IOLs) with respect to overall satisfaction with near and distance vision, visual acuity, dysphotopsia symptoms, spectacle dependence, and mesopic best corrected contrast sensitivity (MBCCS). Materials and Methods: This non-randomized, retrospective, single-centre, comparative study took place at the Kensington Eye Institute in Toronto, Canada. Subjects implanted with either the TFNT00 IOL (n = 11) or ZXR00 IOL (n = 13) were assessed up to 4 years post operatively. Overall satisfaction with distance and near vision, corrected distance visual acuity, uncorrected visual acuity at distance, intermediate (60 cm) and near (40 cm) (UNVA), dysphotopsia symptoms, spectacle dependence and monocular MBCCS were evaluated. Results: Forty-eight eyes of 24 subjects (mean age 68 years, 54% female) were assessed. There was no difference in overall satisfaction; both groups had a median score of 10/10 for overall distance vision, and 7/10 and 8/10 for near vision for EDF and trifocal, respectively. MBCCS at the higher spatial frequencies was significantly better with the ZXR00 IOL. Potentially clinically relevant but not statistically significant differences were found; the trifocal group (vs the EDF group) had better binocular UNVA (20/24 vs 20/32) and less spectacle dependence at least some of the time (54% vs 85%). Conclusion: The ZXR00 may be preferred for those who want optimal contrast sensitivity in dim lighting. Consistent with previous studies, the TFNT00 trifocal IOL may be a better choice for those who want to optimize UNVA. More studies in North America are required to further investigate spectacle dependence.

Supply and demographic characteristics of Ontario's ophthalmologists from 2010 to 2019: a population-based analysis.

BACKGROUND: With an aging population in Ontario, ophthalmologists provide most of their care to older adults, which has prominent human resource implications. In this study, we sought to investigate the supply and demographic characteristics of Ontario's ophthalmologists. METHODS: In this retrospective, population-based analysis, we evaluated cohort demographics, including sex and career stage, of Ontario's ophthalmologists from 2010 to 2019, which we reported using descriptive statistics. Similarly, we detailed ophthalmologist supply within different areas of care using descriptive statistics. RESULTS: Over the study period, a median of 464 ophthalmologists were practising in Ontario each year. The proportion of female ophthalmologists increased from 18.7% in 2010 to 24.1% in 2019. The proportion of late-career ophthalmologists (aged > 55 yr) significantly increased by 6.4% over the study period and constituted 45.3% of the workforce in 2019. Comprehensive cataract surgery was the most common area of care. Although the number of ophthalmologists per 100 000 people remained stable over the study period (3.27 ophthalmologists/100 000 people in 2019), the number of ophthalmologists per 100 000 people aged 65 years and older fell by 18.4% from 2010 to 2019. The greatest supply reduction was among moderate-volume comprehensive cataract surgeons (-20.2% overall and -35.4% relative to the population aged ≥ 65 yr). INTERPRETATION: Between 2010 and 2019, the overall number of ophthalmologists in Ontario remained stable; however, we observed declines in the number of ophthalmologists per 100 000 people aged 65 years and older for most areas of care. Nearly half of the ophthalmology workforce is now older than 55 years and female representation is increasing.

University of Toronto's redesigned ophthalmology curriculum and eye dissection lab.

OBJECTIVE: To present a multifaceted approach to ophthalmology undergraduate medical education and to assess the efficacy of an eye dissection laboratory in enhancing medical student learning. DESIGN: Curriculum review, validation, and student feedback evaluations. PARTICIPANTS: Year 2 medical students enrolled in the University of Toronto's Doctor of Medicine Program. METHODS: Student feedback evaluations were compiled from the University of Toronto undergraduate medical education student surveys before 2012-2016 and following introduction of the redesigned foundations ophthalmology curriculum at the University of Toronto (2017-2018). Students who participated in the Eye Dissection Lab as part of the newly designed curriculum completed the pre- and postsession satisfaction and overall interest in ophthalmology questionnaires and a knowledge-based test. RESULTS: Analysis of 1640 student evaluations demonstrated an increase in ophthalmology curriculum rating following the launch of the foundations ophthalmology curriculum (p = 0.015). Among the 335 students who completed the eye dissection lab, there was a significant increase in the average scores for the satisfaction questionnaire, knowledge-based test, and level of interest in the field of ophthalmology from before and after the session, with improvements in scores noted in 91%, 42%, and 36% of the educational parameters of the participants, respectively (p < 0.001). CONCLUSIONS: The newly designed foundations ophthalmology curriculum and the eye dissection lab at the University of Toronto serve as effective means for enhancing ophthalmology teaching in medical schools across Canada.

Clinical features of endophthalmitis clusters after cataract surgery and practical recommendations to mitigate risk: systematic review.

Intraocular transmission of exogenous pathogens in cataract surgery can lead to endophthalmitis. This review evaluates the features of endophthalmitis clusters secondary to pathogen transmission in cataract surgery. Articles reporting on pathogen transmission in cataract surgery were identified via searches of Ovid MEDLINE, EMBASE, and Cochrane CENTRAL, and a total of 268 eyes from 24 studies were included. The most common source of infectious transmission was attributed to a contaminated intraocular solution (ie, irrigation solution, viscoelastic, or diluted antibiotic; n = 10). Visual acuity at presentation with infectious features was 1.89 logMAR (range: 1.35 to 2.58; ∼counting fingers) and 1.33 logMAR (range: 0.04 to 3.00; Snellen: ∼20/430) at last follow-up. Patients with diabetes had worse outcomes compared with patients without diabetes. The most frequently isolated pathogen from the infectious sources was Pseudomonas sp. (50.0%). This review highlights the various routes of pathogen transmission during cataract surgery and summarizes recommendations for the detection, prevention, and management of endophthalmitis clusters.

Impact of discontinuing government-funded routine eye exams on new glaucoma diagnoses in Ontario.

OBJECTIVE: In 2004, government-funded routine eye exams were discontinued for individuals aged 20-64 years in Ontario. We assessed whether this policy change reduced the rate of new glaucoma diagnoses. DESIGN: Cohort-based time-series analysis. PARTICIPANTS: Ontarians aged 20+ years in 2000-2014. METHODS: Province-wide physician billing data were analyzed using segmented regression analysis. New glaucoma diagnoses were defined as the first glaucoma diagnostic billing code submitted by an ophthalmologist or optometrist among Ontarians who did not visit an ophthalmologist or an optometrist in the year prior to the study year. RESULTS: Post- versus pre-2004, the rate of new glaucoma billings was reduced in all age groups: -2.7‰ (p < 0.0001) in the age group 20-39 years, -8.2‰ (p < 0.0001) in the age group 40-64 years (p < 0.0001), and -2.1‰ (p = 0.0003) in the age group 65+ years. This corresponds to a decreased number of individuals with a new glaucoma billing after 2004 versus before 2004: -8,800 (p < 0.001) in the age group 20-39 years, -32,234 (p < 0.0001) in the age group 40-64 years, and -3,255 (p = 0.0012) in the age group 65+ years. Reduced rates of new glaucoma diagnostic billings were seen in males, females and rural and urban residents among policy-affected and policy-unaffected age groups. Ontarians living in the wealthiest neighbourhood areas also had a significantly reduced rate after versus before 2004: -2.7‰ (p < 0.0001) for the age group 20-39 years, -9.0‰ (p < 0.0001) for the age group 40-64 years, and -2.3‰ (p < 0.001) for the age group 65+ years. CONCLUSIONS: Discontinuation of government-funding for routine eye exams was associated with a significantly reduced rate of new glaucoma diagnostic billings irrespective of sociodemographics. More research is needed to understand the reduced glaucoma billings in unaffected seniors and those living in the wealthiest neighbourhood areas.

The ophthalmic surgical backlog associated with the COVID-19 pandemic: a population-based and microsimulation modelling study.

BACKGROUND: Jurisdictions worldwide ramped down ophthalmic surgeries to mitigate the effects of COVID-19, creating a global surgical backlog. We sought to predict the long-term impact of COVID-19 on the timely delivery of non-emergent ophthalmology sub-specialty surgical care in Ontario. METHODS: This is a microsimulation modelling study. We used provincial population-based administrative data from the Wait Time Information System database in Ontario for January 2019 to May 2021 and facility-level data for March 2018 to May 2021 to estimate the backlog size and wait times associated with the COVID-19 pandemic. For the postpandemic recovery phase, we estimated the resources required to clear the backlog of patients accumulated on the wait-list during the pandemic. Outcomes were accrued over a time horizon of 3 years. RESULTS: A total of 56 923 patients were on the wait-list in the province of Ontario awaiting non-emergency ophthalmic surgery as of Mar. 15, 2020. The number of non-emergency surgeries performed in the province decreased by 97% in May 2020 and by 80% in May 2021 compared with the same months in 2019. By 2 years and 3 years since the start of the pandemic, the overall estimated number of patients awaiting surgery grew by 129% and 150%, respectively. The estimated mean wait time for patients for all subspecialty surgeries increased to 282 (standard deviation [SD] 91) days in March 2023 compared with 94 (SD 97) days in 2019. The provincial monthly additional resources required to clear the backlog by March 2023 was estimated to be a 34% escalation from the prepandemic volumes (4626 additional surgeries). INTERPRETATION: The estimates from this microsimulation modelling study suggest that the magnitude of the ophthalmic surgical backlog from the COVID-19 pandemic has important implications for the recovery phase. This model can be adapted to other jurisdictions to assist with recovery planning for vision-saving surgeries.

A comparative analysis of 12 intraocular lens power formulas.

PURPOSE: To evaluate the accuracy of 12 intraocular lens (IOL) power calculations: Barrett Universal II, EVO, Haigis, Hill-RBF version 2.0, Hoffer Q, Holladay 1, Holladay 2, Kane, Olsen, SRK/T, Super Formula and T2. METHODS: In this retrospective consecutive case series, cataract extraction and IOL implantation cases in Toronto, Canada, were recruited between 2017 and 2019. Refractive predictions were compared to the observed 1-month postoperative spherical equivalent to determine the refractive error for each formula cohort. Subgroup analysis stratified eyes into short (≤ 22.5 mm)-, intermediate (22.5 mm-25.5 mm)- and long (≥ 25.5 mm)-axial length (AL) cohorts. The primary outcome was the percentage of cases within ± 0.50D of refractive error. RESULTS: Overall, 764 cataract cases were analyzed. Formulas with the highest percentage of eyes within ± 0.50D of refractive error, in decreasing order, were: Kane (77.7%), Barrett Universal II (77.4%), EVO (76.6%), T2 (76.4%), Super (75.9%), Holladay 1 (75.4%), Hill-RBF 2.0 (74.7%), SRK/T (72.6%), Hoffer Q (72.5%), Haigis (71.7%), Olsen (67.4%) and Holladay 2 (67.3%). For short-AL eyes, the Holladay 1 formula was most accurate (n = 69, 78.3% within ± 0.50D), and for long-AL eyes, the Barrett Universal II formula was most accurate (n = 116, 76.7% within ± 0.50D). Kane, Barrett, EVO, T2 and Super formulas led to a significantly lower mean absolute error compared to the open-source calculations with optimized lens constants (p-value: < 0.001-0.042). CONCLUSIONS: The Kane formula was the most accurate formula for the overall analysis. The Holladay 1 calculation was most accurate for short-AL cases, whereas the Barrett Universal II was superior for long-AL eyes.