The goal of this systematic review was to evaluate the measurement variability of distance visual acuity (VA) and refractive error (RE).

Accurately measuring VA and RE is fundamental to eyecare, however, no scientific consensus has been reached on the measurement variability. Scientific literature suggests limits of variability of ±0.15 Logarithm of the Minimum Angle of Resolution (LogMAR) for VA and ±0.5 Diopters (D) for RE. This lack of consensus on variability affects our clinical decision-making, regulations, and research.

This systematic review was performed in accordance with PRISMA guidelines and was registered at PROSPERO (ID CRD42024554663). We searched the Medline, PubMed, and Embase databases. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was then used to assess the risk of bias (RoB). We included studies of adults that directly compared distance VA or RE and reported the Limits of Agreement (LoA) and mean difference. An overall summarized mean is reported in LoA and the certainty of evidence was assessed using GRADE.

After applying the eligibility criteria, 12 studies reporting on VA and 6 studies reporting on RE were included. Six out of the 18 studies (33%) scored a low RoB in at least three out of four QUADAS-2 domains. In 25 out of 36 subgroups (69%), the LoA exceeded the suggested clinical accepted variability ranges for VA (±0.15LogMAR) or RE (±0.5D). The overall summarized mean is ±0.20LogMAR (95%CI 0.17;0.23) for VA and ±0.70D (95%CI 0.50;0.89) for RE. The GRADE certainty of evidence was very low.

This study demonstrates that distance VA and RE measurements have a high measurement variability in adults, exceeding the suggested limits of variability (VA: ±0.15LogMAR, RE: ±0.5D). The evidence either fails to support the suggested limits of variability or is based on studies with methodological weaknesses, with a very low certainty of evidence. Methodological rigorous studies are therefore needed to accurately estimate the suggested limits of variability. For now, we propose using the overall summarized mean LoA obtained in our study as a provisional frame of reference (i.e. ±0.20LogMAR and ±0.70D).

To evaluate the ability of the monocular QuickSee Free (QSF) portable autorefractor (PlenOptika) to detect and measure refractive error relative to gold standard cycloplegic retinoscopy in a population of school-aged children in a low-resource setting in The Gambia.

A total of 101 children, aged between 3 and 17 years (10.2 ± 3.45 years) underwent visual acuity screening, autorefraction by the QSF, and complete ophthalmic examination including cycloplegic retinoscopy. The agreement of the results was evaluated by Bland-Altman plots. The sensitivity and specificity of detecting myopia, anisometropia, and astigmatism were calculated based on the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) 2021 guidelines. The overall accuracy of detecting refractive error was analyzed with receiver operating characteristic curves.

Spherical equivalent (SE), sphere, and cylinder of the QSF all displayed moderate interclass correlation with cycloplegic retinoscopy with cylinder correlating the highest with physician measurements followed by SE, then sphere. The average bias for the QSF was slightly negative for sphere and spherical equivalents, indicating that on average the QSF tended to underestimate these measures relative to physicians. Based on AAPOS 2021 guidelines, the sensitivity and specificity (in respective order) were 62% and 93% for detecting myopia, 57% and 86% for detecting anisometropia, and 78% and 95% for detecting astigmatism. The area under the receiver operating characteristic curve was greater than 0.75 for all three conditions, suggesting the QSF has good predictive ability to detect myopia, anisometropia, and astigmatism.

The QSF displayed moderate agreement with physician reported refractions and it also tended to underestimate spherical equivalents and sphere. The device exhibited high predictability in detecting refractive error in the low-resource setting. [J Pediatr Ophthalmol Strabismus. 2025;62(2):122-127.].

Quality-of-care in refractive error services is essential, as it directly affects vision outcomes, wellbeing, educational attainment, and workforce participation. In Cambodia, uncorrected refractive error is a leading cause of mild and moderate vision impairment in adults. We evaluated the quality of refractive error care in Cambodia by estimating the proportion of prescribed and dispensed spectacles appropriate for people's refractive error needs and factors associated with spectacle quality.

A cross-sectional protocol was employed with 18 Khmer-speaking adult participants observing testing procedures in 156 optical services across six provinces in 2022. A total of 496 dispensed spectacles were assessed against spectacle quality indicators.

The analysis revealed that 35.1% of dispensed spectacles were of optimal quality. The most common error observed in sub-optimal spectacles was the presence of horizontal prism outside of tolerance limits. The study also found that 44.0% of emmetrope visits involved unnecessary prescription spectacle recommendations, and 18.3% of written prescriptions did not correspond with dispensed spectacles. Sex differences were observed, with men predominantly providing refractive error care and women more likely to be unnecessarily recommended prescription spectacles.

The findings highlight the importance of prioritizing quality-of-care in refractive error services. A key recommendation is to consider regulatory mechanisms to ensure optical services employ appropriately qualified staff. Additionally, efforts should be made to eliminate unnecessary prescriptions -- especially for emmetropes and females -- standardize written prescriptions, ensure consistent pupil distance measurements, reduce reliance on autorefraction, and address the gender imbalance in the refractive error workforce.

The Street Medicine Auto-Refraction Technology study is an efficient and cost-effective treatment of refractive error (RE) and identification of potential non-RE pathology in people experiencing homelessness (PEHs).

Outreach evaluation for diagnosis and treatment.

The internal medicine physicians/staff team used a protocol designed by ophthalmology to screen and treat PEHs. First, the uncorrected visual acuity (ucVA) was measured, which was defined as a patient's visual acuity without the use of any glasses. Those with 2-line improvement on pinhole testing (phVA) underwent handheld portable autorefraction (AR). During a second encounter, glasses purchased from the AR measurements were distributed, and vision was remeasured with the new glasses or current corrected visual acuity (ccVA). Patients with a final VA ≥0.3 logMAR (equivalent to Early Treatment Diabetic Retinopathy Study 20/40) were referred to an ophthalmology clinic for further evaluation.

This was a prospective study of 117 patients (226 eyes). ucVA was 0.64 logMAR (equivalent to Early Treatment Diabetic Retinopathy Study 20/87) for both the OD and the OS. A total of 90 of 98 (91.8%) patients successfully underwent AR; 80 of 88 (90.1%) patients received their glasses. For the 61 patients who completed their second visit, the average improvement in VA (ccVA - ucVA) was 5 lines. Twenty-three of 117 (19.7%) were referred to ophthalmology for further evaluation. Poststudy Likert surveys (1 = strongly disagree to 5 = strongly agree) showed patient satisfaction with the testing (4.7), the AR (4.6), seeing better (4.8), and doing activities with glasses (4.7). In addition, most patients agreed that they would not have obtained glasses without the study (4.7).

This is a new model to screen RE and provide affordable glasses to PEHs in a nonambulatory setting. Patients with potential non-RE can be sent for further evaluation.

To evaluate effects and related factors of short-time accommodation training on measuring consistency of InnovEyes Sitemap (Alcon/WaveLight; Alcon Laboratories, Inc), NIDEK ARK-1 autorefractor (Nidek Corporation), and subjective refraction (SR).

One hundred adults (100 eyes) with myopia aged 17 to 40 years were enrolled. Refraction was obtained by InnovEyes Sitemap, autorefraction, and SR in a randomized order. Refractive data of InnovEyes Sitemap were grouped into two groups without and with application of a 2.00 diopter (D) flipper before InnovEyes Sitemap.

The average difference in spherical equivalent (SE) between InnovEyes Sitemap and SR (autorefraction) decreased from -0.56 ± -0.41 D in the without accommodation training group to -0.29 ± -0.14 D in the with accommodation training group, with 95% CI of limits of agreement (LOA) shrinking dramatically (InnovEyes Sitemap-SR: -1.39 to 0.27 vs -0.71 to 0.14 D; InnovEyes Sitemap-autorefraction: -1.23 to 0.40 vs -0.69 to 0.40 D). Furthermore, short-time accommodation training significantly improved the consistency of myopia measurements, with the proportion of SE differences within 0.50 D between InnovEyes Sitemap and SR significantly increasing from 56% to 88% (P < .001). Meanwhile, J0 and J45 showed no significant difference (P > .05) with similar LOA among three techniques in both groups. SE difference of InnovEyes Sitemap (with accommodation training group minus without accommodation training group) was significantly correlated to SE difference between SR and habitual glass refraction (β = -0.312, P = .001), lens thickness (β = 0.262, P = .006), and axial length (β = 0.199, P = .037).

Short-time accommodation training could promote spherical consistency but not deteriorate cylindrical agreement among InnovEyes Sitemap, autorefraction, and SR, and this effect showed more effective in eyes with more undercorrected myopia in habitual prescription, thicker lens, and longer axial length. [J Refract Surg. 2024;40(12):e941-e955.].

Retinoscopy is arguably the most important method in the eye clinic for diagnosing and managing refractive errors. Advantages of retinoscopy include its non-invasive nature, ability to assess patients of all ages, and usefulness in patients with limited cooperation or communication skills.

To discuss the history of retinoscopes and examine current literature on the subject.

A search was conducted on the PubMed and with the reference citation analysis (https://www.referencecitationanalysis.com) database using the term "Retinoscopy," with a range restricted to the last 10 years (2013-2023). The search string algorithm was: "Retinoscopy" (MeSH Terms) OR "Retinoscopy" (All Fields) OR "Retinoscopes" (All Fields) AND [(All Fields) AND 2013: 2023 (pdat)].

This systematic review included a total of 286 records. Publications reviewed iterations of the retinoscope into autorefractors, infrared photo retinoscope, television retinoscopy, and the Wifi enabled digital retinoscope.

The retinoscope has evolved significantly since its discovery, with a significant improvement in its diagnostic capabilities. While it has advantages such as non-invasiveness and broad applicability, limitations exist, and the need for skilled interpretation remains. With ongoing research, including the integration of artificial intelligence, retinoscopy is expected to continue advancing and playing a vital role in eye care.

Currently eye examinations are usually based on autorefraction followed by subjective refraction (SR) with a phoropter. An automated phoropter that can also perform autorefraction may facilitate the optometric workflow.

The efficiency and feasibility of an objective autorefraction and correction system are assessed by comparing objective refractive measurements with SR on the same subjects and evaluating the visual acuity (VA) values obtained after the objective refractive measurement and correction.

Objective autorefraction and correction was performed on 41 subjects using an automated binocular phoropter system. The auto-phoropter performs autorefraction by wavefront measurement and corrects the spherical and cylindrical errors with tunable fluidic lenses while the patient looks at a visual display inside the instrument. The instrument outputs are optometric constants of spherical and cylindrical aberrations. After measurement and automated correction of the refractive errors, the VA values were assessed by having the subjects look at an integrated Snellen chart. The objective measurement results were statistically compared with their SR.

The correlations between SR and objective autorefraction and correction spherical equivalents (M) were 0.98 (0.97-0.99) and 0.96 (0.93-0.98), the vertical Jackson cross cylinder (J0) were 0.96 (0.92-0.98) and 0.95 (0.91-0.97), and the oblique Jackson cross cylinder (J45) were 0.73 (0.55-0.85) and 0.82 (0.69-0.90), for the right and left eyes, respectively, with the 95% confidence interval (CI) values in parentheses. 89.0% of the 82 eyes had at least 6/7.5 VA.

A significant agreement between the SR and objective autorefraction and correction was observed. An all-objective refractive assessment with instantaneous verification may improve the precision of eye prescriptions and possibly reduce the procedure time.

Uncorrected refractive error is a leading cause of vision impairment which, in most cases, can be managed with the appropriate spectacle correction. In 2021, the World Health Assembly endorsed a global target of a 40-percentage-point increase in effective coverage of refractive error by 2030. To achieve this global target, equitable access to refractive and optical services within community and primary care settings needs to be strengthened. This review will inform the development of technical guidance to support improvements in the testing and correction of refractive error among World Health Organization (WHO) member states.

To determine the range of approaches for delivery of refractive and optical care services in community and primary care settings, and the methods employed for their evaluation.

We searched CENTRAL, MEDLINE, Embase and Global Health databases, grey literature, and annual reports and websites of relevant organizations involved in eye-care delivery from January 2002 to November 2022 to identify approaches for refractive and optical service delivery.

We included observational and interventional studies, reviews, and reports from relevant organizations related to delivering refractive services and optical services for preschool and school-aged children and adults in community and primary care settings published between January 2002 and November 2022. We searched for studies and reports published within the last 20 years because vision impairment due to uncorrected refractive error has only recently become a public health and eye health priority, therefore we did not expect to find much relevant literature until after 2002.

Two review authors screened titles, abstracts and full texts, and extracted data. We resolved any discrepancies through discussion. We synthesized data, and presented results as tables, figures, and case studies. This project was led by the World Health Organization (WHO) Vision and Eye Care Programme.

We identified 175 studies from searches of databases and grey literature, 146 records from company reports, and 81 records from website searches of relevant organizations that matched our inclusion criteria. Delivery approaches for refractive and optical services in community care included school-based, pharmacy, and outreach models, whereas primary care approaches comprised vision centre, health centre, and a combination of vision or health centre and door-to-door delivery. In community care, school-based and outreach approaches were predominant, while in primary care, a vision-centre approach was mainly used. In the WHO African region, the school-based and outreach approaches were mainly reported while, in the Americas, the outreach approach was mostly used. Very few approaches for service delivery were reported in the WHO Eastern Mediterranean region. Prominent gaps exist in the evaluation of the approaches, and few studies attempted to evaluate the approaches for delivery of refractive and optical care services.

We comprehensively describe a range of approaches for delivery of refractive and optical services in community and primary care. Further evaluation of their effectiveness will better inform the application of these service-delivery approaches. The study outcomes will help guide WHO member states in strengthening refractive and optical services at community and primary care levels.

This scoping review was supported by the Vision and Eye care Programme, World Health Organization and ATscale Global Partnership.

The protocol of this scoping review was published in the Open Source Framework.

Despite the well-known reproducibility issues of subjective refraction, most studies evaluating autorefractors compared differences between the device and subjective refraction. This work evaluated the performance of a novel handheld Hartmann-Shack-based autorefractor using an alternative protocol, which considered the inherent variability of subjective refraction.

Participants underwent an initial measurement with a desktop autorefractor, two subjective refractions (SR1 and SR2) and a final measurement with the QuickSee Free (QSFree) portable autorefractor. Autorefractor performance was evaluated by comparing the differences between the QSFree and each of the subjective refractions with the difference between the subjective refractions (SR1 vs. SR2) using Bland-Altman analysis and percentage of agreement.

A total of 75 subjects (53 ± 14 years) were enrolled in the study. The average difference in the absolute spherical equivalent (M) between the QSFree and the SR1 and SR2 was ±0.24 and ±0.02 D, respectively, that is, very similar or smaller than the SR1 versus SR2 difference (±0.26 D). Average differences in astigmatic components were found to be negligible. The results demonstrate that differences between QSFree and both subjective refractions in J0 and J45 were within ±0.50 D for at least 96% of the measurements. The limits of agreement (LOAs) of the differences between QSFree and SR1, as well as QSFree and SR2, were higher than those observed between SR1 and SR2 for M, J0 and J45 .

A protocol was designed and validated for the evaluation of a refractive device to account for the variability of subjective refraction. This protocol was used to evaluate a novel portable autorefractor and observed a smaller difference between the device and subjective refractions than the difference between the two subjective refraction measurements in terms of mean bias error, although the standard deviation was higher.

The evaluation of refractive error is probably the most important and common procedure in eye care. The gold standard method for evaluating refractive error is subjective refraction, a process that has not significantly changed in 200years. This article aims to review recent technologies and novel approaches attempting to improve this traditional procedure.

From laboratory prototypes to commercial instruments, the proposed methods aim to perform reliable and fast subjective refractions, following different approaches: using motorized phoropters in combination with automatic algorithms or even self-refraction, hybridizing objective and subjective measurements within the same instruments, or using new visual tasks beyond letter identification of blur estimation to obtain the refractive error subjectively.

The current trend in subjective refraction is to overcome the traditional manual blur reduction method, using automatic and self-refraction instruments, which can provide faster measurements with lower variability. Many of the technologies reported here are already in the market, and some have the potential of becoming the new standard in subjective refraction.