Self correction of refractive error among young people in rural China: results of cross sectional investigation

Abstract

Objective To compare outcomes between adjustable spectacles and conventional methods for refraction in young people.Design Cross sectional study.Setting Rural southern China.Participants 648 young people aged 12-18 (mean 14.9 (SD 0.98)), with uncorrected visual acuity ≤6/12 in either eye.Interventions All participants underwent self refraction without cycloplegia (paralysis of near focusing ability with topical eye drops), automated refraction without cycloplegia, and subjective refraction by an ophthalmologist with cycloplegia.Main outcome measures Uncorrected and corrected vision, improvement of vision (lines on a chart), and refractive error.Results Among the participants, 59% (384) were girls, 44% (288) wore spectacles, and 61% (393/648) had 2.00 dioptres or more of myopia in the right eye. All completed self refraction. The proportion with visual acuity ≥6/7.5 in the better eye was 5.2% (95% confidence interval 3.6% to 6.9%) for uncorrected vision, 30.2% (25.7% to 34.8%) for currently worn spectacles, 96.9% (95.5% to 98.3%) for self refraction, 98.4% (97.4% to 99.5%) for automated refraction, and 99.1% (98.3% to 99.9%) for subjective refraction (P=0.033 for self refraction v automated refraction, P=0.001 for self refraction v subjective refraction). Improvements over uncorrected vision in the better eye with self refraction and subjective refraction were within one line on the eye chart in 98% of participants. In logistic regression models, failure to achieve maximum recorded visual acuity of 6/7.5 in right eyes with self refraction was associated with greater absolute value of myopia/hyperopia (P<0.001), greater astigmatism (P=0.001), and not having previously worn spectacles (P=0.002), but not age or sex. Significant inaccuracies in power (≥1.00 dioptre) were less common in right eyes with self refraction than with automated refraction (5% v 11%, P<0.001).Conclusions Though visual acuity was slightly worse with self refraction than automated or subjective refraction, acuity was excellent in nearly all these young people with inadequately corrected refractive error at baseline. Inaccurate power was less common with self refraction than automated refraction. Self refraction could decrease the requirement for scarce trained personnel, expensive devices, and cycloplegia in children’s vision programmes in rural China.

Reversing the Trend of Large Scale and Centralization in Manufacturing: The Case of Distributed Manufacturing of Customizable 3-D-Printable Self-Adjustable Glasses

“…The Adspec lens is composed of two thin circular membranes sealed at the edges and filled with a fluid with an index of refraction, n, of 1.579 [42]. The optical power of the lens is a function of the surface curvature, which is determined by the volume of the fluid in between the membranes.…”

“…Hence by varying the fluid volume, the optical power of the lens can also be varied to the desired value. Mounting two adaptive lens on a specialized spectacle frame results in an adaptive spectacles (Adspecs) [42], which offers the user to ability to adjust the refractive power of each lens to achieve self-refraction. The useful power range of the lenses was reported to be −6 D to +12 D [42].…”

“…The use of wearer adjustable eyeglasses solves two problems: first, it reduces the need for measurement by a trained refractionist, which is crucial for regions with few eye care professionals. Secondly, it offers a much simpler and far cheaper deployment compared to a more conventional approach based on lens grinding or stock optics [30,[38][39][40][41][42]. Self-adjusting eyeglasses would make vision correction accessible particularly to those in the developing world where there is either a lack of professionally trained optometrists and ophthalmologists, or where the cost of traditional spectacle lenses and professional consultation is prohibitively expensive [42].…”

Validation of Near Eye Tool for Refractive Assessment (NETRA) – Pilot Study

“…With a pair of basic prescription spectacles costing as little as $1 to produce, this lack of human resource is a major contributor to treatable visual loss due to URE in resource poor countries. Most attempts to address this unmet need have been unsuccessful, with a large reliance on volunteer organisations and overly complicated modifiable spectacles 5 . Following Tudor Hart's 'inverses-care-law' local optometric services tend to be private, and unevenly distributed; making them unaffordable and inaccessible to many to the urban poor and those living in rural areas.…”

Comparison between focometer and autorefractor in the measurement of refractive error among students in underserved community of sub-Saharan Africa

“…3 URE is the single largest contributor to the global burden of eye diseases 4 and among children it is the leading and most easily remedied cause of poor vision. 5 The prevalence of refractive error among school students in Nigeria varies between 1.97% and 5.8%. [6][7][8] School children are an important large target group for detection of eye diseases 9 and this early detection provides the best opportunity for effective treatment thereby preventing blindness.…”