Correcting refractive error with spectacles: a simple solution but a global challenge

Uncorrected refractive error is the leading cause of visual impairment and the second cause of blindness worldwide. Vision impairment from uncorrected refractive error is responsible for a reduction in quality of life and can negatively affect employability and productivity of adults. Because the correction of refractive error can be remedied easily and completely with appropriate spectacles, the World Health Organization and the International Agency for the Prevention of Blindness have placed uncorrected refractive error as one of the priorities for Vision 2020 at the elimination of avoidable blindness. Nevertheless, from 1990 to 2010, the proportions of vision impairment and blindness due to uncorrected refractive error have changed little and remained high. Worldwide, uncorrected refractive error led to 53% of vision impairment and 21% of blindness in 2010. The proportion of vision impairment and blindness caused by uncorrected refractive error was largest in the South Asia region (65% and 36%, respectively). Despite the public health significance of uncorrected refractive error, data on prevalence and pattern of spectacle use are very limited in developing countries. In this edition of Clinical and Experimental Ophthalmology, Marmamula et al. investigated the prevalence of spectacles use and spectacle coverage in South India, state of Andhra Pradesh, where refractive error accounts for 48% of total visual impairment. Data from this large-scale population-based study showed that almost 30% of participants were presently using spectacles for distance and/or near vision, with bifocals as the most common form of spectacle corrections and private eye clinics as the leading spectacles providers. However, the rate of spectacle coverage was low: only 38% in people with refractive error and 27% in those with presbyopia. Marmamula et al. introduced a new indicator, spectacle benefit rate (SBR), to quantify the effective use of spectacles among spectacles users. Among current spectacles users, spectacles benefit was deemed to be present if an individual who had unaided distance visual acuity (VA) worse than 6/12 in the better eye and showed an improvement to 6/12 or better with own spectacles, or those who had unaided near vision worse than Notation 8 (N8) and improved to N8 or better with their spectacles. Based on this, the SBR showed that only about half of the spectacle users benefited from their current prescription. However, there were at least two groups of spectacle users that could have as well “benefited” but were not considered. The first group was the spectacle users who have shown an improvement but not to the level of 6/12 or N8, either due to under correction or other ocular comorbidity. The second group was the spectacle users with unaided VA better than 6/12 or N8 but still showed an improvement with own spectacles. Therefore, the current SBR indicator could be an underestimation of the people who may have benefited from spectacle used. An alternative calculation could examine the proportions of people who had unaided distance VA worse than 6/12 in the better eye and subsequently show an improvement of two VA lines. One could also develop an indicator to measure whether individuals experience an improvement in their visual functioning, when using spectacles, to meet their daily living requirements. Using multiple logistic regression analysis, Marmamula et al. found that spectacle use was independently associated with increasing age, higher levels of education and interestingly, higher for residents living in the rural than urban region. But they failed to determine the factors or barriers (e.g. accessibility to optical services) that were independently associated with low spectacle coverage and ineffective use of spectacles. Those factors would be more relevant for public health interventions to improve the availability and quality of refraction and eye care service in a given region. In other developing countries where there is a shortage of eye care services, volunteer-based organizations from developed countries have traditionally been making short visits to provide services such as