Academic journal article Bulletin of the World Health Organization

Refractive Error Blindness

Academic journal article Bulletin of the World Health Organization

Refractive Error Blindness

Article excerpt

Voir page 242 le resume en francais. En la pagina 242 figura un resumen en espanol.

Introduction

Refractive error as a cause of blindness has not received much attention because many definitions of blindness have been based on best-corrected distance visual acuity, including the definition used in the International Statistical Classification of Diseases and Related Health Problems (1). However, in many parts of the world refractive error would become the second largest cause of treatable blindness after cataract if blindness were defined on the basis of presenting distance visual acuity (2-10). Refractive error is also one of the most common causes of visual impairment (3-5, 9-13).

Because of the increasing realization of the enormous need for correction of refractive error worldwide, this condition has been considered one of the priorities of the recently launched global initiative for the elimination of avoidable blindness: VISION 2020 -- The Right to Sight (14, 15). For the most part, refractive error can be easily corrected with spectacles, which makes it imperative that effective strategies be developed to eliminate this easily treatable cause of blindness.

This review presents a summary of the current and likely future issues related to blindness due to refractive error.

Definition of blindness

Blindness is defined either in terms of best-corrected distance visual acuity (the most appropriate refractive correction) or presenting distance visual acuity (the individual's current refractive correction) in the better eye. The latter definition permits assessment of blindness due to refractive error, whereas the former does not. Although a large amount of data are available on the prevalence of blindness in different parts of the world (16), data on the prevalence of blindness due to refractive error are not readily available because the presenting distance visual acuity definition is not always used.

Also of importance in the definition of blindness is the level of visual acuity that is applied. Visual acuity levels of [is less than] 3/60 or [is less than] 6/60 in the better eye have been commonly used to define blindness (2-9). In addition, visual acuity levels [is less than] 6/60 have sometimes been used to define blindness, for example in the USA (10).

Magnitude of refractive error blindness

We carried out a literature search to identify information from different parts of the world on the magnitude of blindness due to refractive error from population-based surveys of blindness published in 1990 or later. The findings are summarized in Table 1 (2-10).

Table 1. Prevalence of blindness due to refractive error reported from
population-based surveys in selected countries

                                                 Age groups
Year of                                            studied
Publication                 Country                (years)

Blindness definition 1(a)

1992                        Pakistan (ref. 2)     All ages
1996                        Turkey (ref. 3)       All ages
1997                        Lebanon (ref. 4)      All ages
1997                        Ethiopia (ref. 5)     All ages
1998                        Tunisia (ref. 6)      All ages
2001                        India (ref. 7)        All ages

Blindness definition 2(b)

1999                        China (ref. 8)           >50
2001                        Australia (ref. 9)       >40
2001                        India (ref. 7)        All ages

Blindness definition 3(c)

1990                        USA (ref. 10)        [is greater than
                                                   or equal to]
                                                   40 (Blacks)
                                                 [is greater than
                                                   or equal to]
                                                   40 (Whites)

                                                     Prevalence of
Year of                     Sample   Prevalence     blindness due to
Publication                 size     of blindness   refractive error

Blindness definition 1(a)

1992                        29 139      1. … 
Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.