Treating uncorrected refractive error in adults in the developing world with autorefractors and ready-made spectacles

Approaches for delivery of refractive and optical care services in community and primary care settings

BACKGROUND

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.

OBJECTIVES

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.

SEARCH METHODS

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.

SELECTION CRITERIA

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.

DATA COLLECTION AND ANALYSIS

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.

MAIN RESULTS

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.

AUTHORS' CONCLUSIONS

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.

FUNDING

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

REGISTRATION

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

Health shock and preference instability: assessing health-state dependency of willingness-to-pay for corrective eyeglasses

BACKGROUND

Differences in contingent valuation (CV) estimates for identical healthcare goods can cast considerable doubt on the true economic measures of consumer preferences. Hypothetical nature of CV methods can potentially depend on the salience, context and perceived relevance of the good or service under consideration. Thus, the high demand elasticity for healthcare goods warrants careful selection of study population as the contexts of valuation significantly changes after experiencing health shock.

METHODS

In this study, using triple-bounded dichotomous choice (TBDC) experiments, we test how negative health shock (namely, being diagnosed with refractive errors), can alter preference over a common health good (namely, corrective eyeglasses). We compared elicited WTP of diagnosed patients with a synthetically constructed comparable cohort without the same health shock, controlling for the possible self-selection using a number of matching techniques based on the observable socio-demographic characteristics.

RESULTS

The consumers diagnosed with vision problems exhibit a rightward shift in their demand curve compared to observationally identical consumers without such problems resulting in about 17% higher consumer surplus. The consumers without the health shock are willing to pay about BDT 762.4 [95% CI: BDT 709.9 - BDT 814.9] for corrective eyeglasses, which gets 15-30% higher for the matched with-health-shock consumers. Multivariable analyses suggest more educated and wealthier individuals are willing to pay respectively BDT 208 and BDT 119 more for corrective eyeglasses. We have tested the models for different matching protocols. Our results are fairly robust to alternate specifications and various matching techniques.

CONCLUSION

The preferences for healthcare goods, such as eyeglasses, can significantly depend upon the respondent being diagnosed with refractive errors. Our findings have implications for general cost-benefit analyses often relying on WTP, which can vary depending on the contexts. There are also increasing interests in cost recovery models, which require understanding the demand for healthcare goods and services. We find eliciting the demand needs to consider the health status of the population from which the respondents are sampled.

Evaluating Self-Refraction and Ready-Made Spectacles for Treatment of Uncorrected Refractive Error

PURPOSE

Uncorrected refractive error is the leading cause of visual impairment worldwide and has significant quality of life and economic implications. Treatment with subjective refraction and custom-made spectacles requires expensive equipment and highly trained personnel. We examine several alternatives.

METHODS

Patients were taught to self-refract using two devices: AdSpecs and the I-test Vision Screener. Ready-made spectacles were fit to the self-refraction and visual acuity (VA) was measured. Donated-spectacles were fit to subjective refraction and VA was measured. Self-refraction and donated spectacles spherical equivalent (SE) and VA were compared to subjective refraction SE and VA.

RESULTS

About 57 patients (102 eyes) were enrolled in the study. Patients accurately determined refractive power with self-refraction by both AdSpecs and the I-test (compared to subjective refraction SE, r² = 0.97 and r² = 0.94, respectively). SE of donated spectacles fit well with self-refraction SE (r² = 0.91). There was no significant difference between best-corrected VA by subjective refraction and VA treated by ready-made spectacles fit to self-refraction by either device (analysis of variance (ANOVA), p non-significant). Patients fit with donated spectacles had significantly worse VA than best-corrected VA by subjective refraction (ANOVA, p < 0.01), although 80% improved to >20/40.

CONCLUSION

Patients accurately self-refract using both devices and ready-made spectacles fit to self-refraction have excellent visual outcomes. Donated spectacles have worse visual outcomes but might be useful in a subset of patients. Ready-made spectacles fit to self-refraction may provide a treatment alternative to uncorrected refractive error.

Patient satisfaction and acceptance of spherical equivalent spectacles correction wear in rural India

PURPOSE

The aim of this study was to explore the possibilities of acceptance of a ready-to-dispense spherical equivalent (SE) of spherocylindrical (SC) correction spectacles in rural India.

METHODS

Snellen visual acuity with SE power of refracted SC lenses was prospectively collected from all individuals visiting vision centers in Phase 1 (vision correction accuracy) of the study conducted in two South Indian districts. The satisfaction level was recorded by asking one standard question. The SE spectacles were dispensed in vision centers of one district in Phase 2 (SE acceptance) with a suggestion to return, if unsatisfied, for free exchange of spectacles within a month of dispensing.

RESULTS

In Phase 1, 929 of 3529 patients were refracted and it was found that 320 patients and one eye of one patient (641 eyes) had astigmatism. The average age was 41 (±16; range: 7-84) years. There was no reduction of visual acuity in SE of 0.25 Dcyl (100% satisfaction) and progressive decrease in satisfaction to 43%, 26%, and 19% with SE correction of 0.50, 0.75, and 1.00 Dcyl, respectively. In Phase 2, 988 of 6168 patients needed refraction and 240 had astigmatism. A total of 103 patients (206 eyes) accepted SE equivalent spectacles. No client returned for the free exchange of spectacles.

CONCLUSION

Dispensing SE power up to 1 Dcyl in ready - made spectacles could be considered in remote rural populations in resource-poor economic conditions.

Analysis of readymade readers and near–inter-pupillary distance for presbyopic patients in optometric practice in Cape Town, South Africa

Purpose and background: This study has particular significance in ophthalmic dispensing as well as for optometry when considering the use of readymade readers (RMRs) both in private practice and in the public health sector. This study investigated firstly whether the optical centre (OC) distance for a sample of RMRs correlates with the near–inter-pupillary distance (near-IPD) for presbyopic patients, whether induced prism occurs with convergence when reading and whether RMR lenses are free of optical strain. Methods: Near-IPDs (measured by a single individual) were obtained from record cards of 1080 patients (540 male patients and 540 female patients). The OC distances were determined for 60 RMRs using a Nikon PL-2 screen vertometer, and induced prismatic effects were calculated for vertical and horizontal meridians. The presence of optical strain was analysed and graded using crossed polarised filters (within a polariscope). Results: The measured average near-IPD was 59.04 mm (s.d. ±2.87) for the 540 female patients and 61.59 mm (s.d. ±3.08) for the 540 male patients. The measured average RMR OC distance was 64.49 mm (s.d. ±3.74) for female patients and 62.77 mm (s.d. ±1.57) for male patients. Based on the mean near-IPD and the corresponding RMR OC distance, the average horizontal prismatic effect found in RMRs designed for female patients with induced prism was 0.11 pd base-out (5.06 mm outwards) and 0.04 pd base-in (1.26 mm inwards). For male RMRs, this was 0.03 pd base-out (1.32 mm outwards) and 0.02 pd base-in (1.28 mm inwards). When comparing RMR distances with near-IPDs, t = -7.87, p < 0.001 for female patients and t = -3.69, p < 0.001 for male patients. The average vertical differential prismatic effect for female patients was 0.67 pd and it was 0.68 pd for male patients. Optical strain was observed in 66.67% and 56.67% of RMR lenses for female and male patients, respectively. The strain pattern was found to be most severe in the inferior temporal periphery for 34 RMRs for female patients and for 20 RMRs for male patients, followed by the inferior nasal periphery for 27 and 18 lenses (RMRs) for male and female patients, respectively. Conclusion: Most RMRs were found to be within international standard tolerances for horizontally induced prismatic effects, but 10% of female and 36.67% of male RMRs had vertical prismatic effects, which exceeded international standards. Significant optical strain was found in the inferior nasal reading portion of the RMRs. Keywords: Readymade readers (RMR’s); prismatic effect; strain; interpupillary distance; presbyopia; reading

Used glasses versus ready-made spectacles for the treatment of refractive error

BACKGROUND AND OBJECTIVE

To compare visual outcomes for used glasses versus ready-made spectacles in the treatment of refractive error.

PATIENTS AND METHODS

In this prospective, comparative case series, undilated refractive error screening examinations were conducted over a 5-week period. Patients with bilateral refractive error were treated with used glasses and ready-made spectacles powered to match their prescriptions. Snellen visual acuity was measured with no correction, best (manifest) correction, unrefined autorefraction, used glasses, and ready-made spectacles. Main outcome measurements were the mean visual improvement from uncorrected acuity and median final visual acuity after treatment with used and ready-made spectacles.

RESULTS

One hundred forty-one patients ages 18 and older with bilateral refractive error were examined. Uncorrected visual acuity in each eye improved an average of 4.5 lines with best correction, 4.0 lines with used glasses, and 3.5 lines with ready-made spectacles, with used glasses demonstrating a statistically significant advantage over ready-made spectacles (P < .001). The median visual acuity in the better eye improved from 20/60 uncorrected to 20/25 with all types of glasses. In patients with less than 1 diopter of anisometropia and greater than 1 diopter of astigmatism in each eye (49%), the ready-made spectacles performed equally as well as the used glasses (P = .95), improving vision an average of 3.9 lines for a median final visual acuity of 20/25 in the better eye.

CONCLUSION

Although both were effective, used glasses are better than ready-made spectacles for improving vision loss due to refractive error.