Modelling ready-made spectacle coverage for children and adults using a large global database

Abstract

Background/aims: To model the suitability of conventional ready-made spectacles (RMS) and interchangeable-lens ready-made spectacles (IRMS) with reference to prescribing guidelines among children and adults using a large, global database and to introduce a web-based application for exploring the database with user-defined eligibility criteria.

Methods: Using refractive power and interpupillary distance data for near and distance spectacles prescribed to children and adults during OneSight clinics in 27 countries, from 2 January 2016 to 19 November 2019, we modelled the expected suitability of RMS and IRMS spectacle designs, compared with custom-made spectacles, according to published prescribing guidelines.

Results: Records of 18 782 presbyopic adult prescriptions, 70 619 distance adult prescriptions and 40 862 paediatric prescriptions were included. Globally, 58.7%-63.9% of adults could be corrected at distance with RMS, depending on the prescribing cut-off. For presbyopic adult prescriptions, coverage was 44.1%-60.9%. Among children, 51.8% were eligible for conventional RMS. Coverage for all groups was similar to the above for IRMS. The most common reason for ineligibility for RMS in all service groups was astigmatism, responsible for 27.2% of all ineligible adult distance prescriptions using the strictest cut-off, 31.4% of children's prescriptions and 28.0% of all adults near prescriptions globally.

Conclusion: Despite their advantages in cost and convenience, coverage delivered by RMS is limited under current prescribing guidelines, particularly for children and presbyopic adults. Interchangeable designs do little to remediate this, despite extending coverage for anisometropia. Our free application allows users to estimate RMS coverage in specific target populations.

Keywords: Epidemiology; Optics and Refraction; Public health; Vision.

Figure 1

Analysis flow chart showing modelled eligibility for different distance and near vision corrective devices following available prescribing protocols. CMS,Custom-made spectacles; DoB, Date of Birth; D,Dioptress; RMS,Ready-made spectacles; IRMS, Interchangable-lens ready-made spectacles; SE, Spherical Equivalent; IPD, Inter-pupillary-distance.