Public health and the eyeEpidemiology of refractive errors and presbyopia☆
Section snippets
Ocular parameters including ethnic variations
The variation with age of ocular parameters relevant to an understanding of age-related changes in refraction has been reviewed.192., 193. Earlier data were based largely on in vivo and in vitro material of Caucasian origin. The advent of ultrasonography has reduced reliance on in vitro measurements, although earlier difficulties linked to an uncertainty regarding the values of the refractive indices pertaining to the various components still persist. Also there has appeared a welcome interest
Genetic influences, sex differences, and familial correlations
The completion of the details of the human genome leaves no room for doubt but that the genetics of refraction and its anomalies will become known. Indeed, two loci for high myopia (<−6D) have now been identified, located on chromosomes 12q21–23 and 18p11.31, respectively.204 The type of myopia was not linked to near-work (see below), as the average age of onset was 5.9 years, the mean refractive error being −9.5 D. However, on a medico-social scale the priority of solving the genetic problem
Prematurity
The careful pioneering work by Fledelius48 has shown that refractive anomalies present at the birth of low-birth-weight children may persist for many years.49 Myopia may affect some 18% of them.153 When one considers that, even in a relatively advanced country, such as the United Kingdom, the prevalence of low birth weight babies is about 6%, the fraction of the total population that is myopic on that score is about 1%: this is not far from an epidemic.36 However, this argument is dwarfed by
Infants and toddlers
Schooling involves near work and therefore has been implicated in the etiology of acquired myopia. Consequently the epidemiology of refractive errors is in the first instance properly focused on pre-school children.
The causes of infant myopia are still being investigated, but, in view of the attention given during the last decade or so to long-term intra-uterine influences,14 it is worth noting that maternal hypertension, preeclampsia and renal disease are liable to lead to a baby's myopia
Phenomenology
The association of myopia, developing in the years leading up to puberty and beyond, with close work is now generally accepted. It finds its physiological basis in the observation that the axial lengths of eyes aged 18–22 years change by 0.06 mm and 0.1 mm during accommodation of 3 D and 8 D, respectively.175 Myopia thus appears to be linked to repeated and/or prolonged accommodation, and we shall see later that this view forms the basis of proposed remedies. In this connection it is
Late-onset myopia
Whereas Goss64 quotes the average annual increase in childhood myopia in Europe and the U.S. as being 0.5 D, it would seem that the late onset involves a slower progress. This was tracked in Norwegian university students with a mean age of 20.6 years:98 over a 3-year period the mean refractive change was −0.5 D (p = 0.0001), that is, three times as slow: this fits comfortably into an extrapolation of Table 7 to an age of 20.5 years. There was a significant relation between the degree of acquired
Age and sex
The description of age-related changes in refraction by Saunders170 has the advantage over all the others in that it provides a graphical frame-work with which to compare other studies. Fig. 8 shows the initial, infant hypermetropia being reduced as a result of emmetropization to zero at an age of ∼14 years in the sample studied. A progression to myopia reaches a maximum around the 30s, and then regresses toward hypermetropia, the maximum of which is reached in the 70s.52 The subsequent change
Refraction and pathology
While it is clear that this topic could be the subject of a review on its own, it would not be right to ignore it altogether, if only to hint at some of the difficulties facing it. Two examples must suffice to illustrate this. As we shall see in a moment, myopia is conventionally seen as a risk factor for primary open-angle glaucoma (POAG). Yet it can also appear as a familial factor in primary angle-closure glaucoma (PACG),76 and PACG is also prevalent among Chinese with a high prevalence of
Prevention
We previously noted that two gene loci for high myopia have been discovered, as a result of which the condition has been described as multigenic: if they should turn out to be the only ones, the condition would probably be called digenic. However, the links between high myopia and associated conditions are still tentative, and we shall have to wait for the situation to be resolved.
In the meantime, concern about the various undesirable sequelae of myopia has not abated, and, with regard to
Presbyopia
Because presbyopia is of relatively minor socio-medical urgency, few population-based study appear to have been published on either the age-related prevalence or incidence of accommodative failure. Therefore, there is no substantial basis for an epidemiology of presbyopia. The risk, in later life, of falling prey to the condition of being unable to focus sharply on near-by objects, such as the printed page, is 100%. There are a few isolated reports of people aged 60 years or more who claim to
Conclusion
It is appropriate that a review of the epidemiology of refractive errors should end with a pointer at Vision 2020, a global initiative200 promoting the elimination of avoidable blindness. In industrially developed countries the idea that refraction could be involved with avoiding blindness may appear strange. Nonetheless Vision 2020 stresses that there are five treatable conditions responsible for 75% of the world's blindness, and refractive errors are one of them. Thus the non-availability of
Summary
- 1.
In the immediate future, a distinction may have to be made between programs designed to address vision correction for developing and developed countries, respectively. The former need first aid to bring corrected vision to a level of at least 25% normal, that is, 20/80 or 6/15. Such countries also need ready help with presbyopic corrections.
- 2.
With regard to industrially more advanced countries, several studies suggest that the degree and prevalence of early onset myopia can be reduced worldwide
Method of literature search
I used Medline and Science on the Internet (the last 30 years). I had access to the library of the Institute of Ophthalmology (University of London), the journal shelves and lists of contents of which I combed. I possess an extensive collection of reprints, and also referred to the extensive bibliographies in my books. I used abstracts of Japanese papers, but ensured that I fully understood the relevant accompanying graphs. The search words used were related to ocular refraction, presbyopia,
References (206)
- et al.
Refractive errors in an older population: the Blue Mountains Eye Study
Ophthalmology
(1999) - et al.
Influence of HLA-DR phenotype and myopia on the risk of nonproliferative and proliferative diabetic retinopathy
Am J Ophthalmol
(1986) The change in lens curvature with age
Exp Eye Res
(1974)On emmetropization
J Theor Biol
(1982)- et al.
Prevalence of lattice degeneration and its relation to axial length in severe myopia
Am J Ophthalmol
(1991) - et al.
Biometry and primary angle-closure glaucoma among Chinese, white, and black populations
Ophthalmology
(1997) - et al.
Corneal curvatures in premature infants
Am J Ophthalmol
(1984) - et al.
The shape of the aging human lens: curvature, equivalent refractive index and the lens paradox
Vision Res
(2001) The development of myopia in Hong Kong children between the ages of 7 and 12 years: a five-year longitudinal study
Ophthalmic Physiol Opt
(1999)- et al.
Anterior chamber depth in Mongolians: variation with age, sex, and method of measurement
Am J Ophthalmol
(1997)
Nearwork and myopia
Lancet
Astigmatism and the development of myopia in children
Vision Res
Response AC/A ratios are elevated in myopic children
Ophthalmic Physiol Opt
Familial aggregation and prevalence of myopia in the Framingham Offspring Eye Study. ramingham Offspring Eye Study Group
Arch Ophthalmol
[The sagittal growth of the eye (authors transl)]
Nippon Ganka Gakkai Zasshi
Natural history of infantile anisometropia
Br J Ophthalmol
Refractive errors in a Finnish rural population
Acta Ophthalmol (Copenh)
Prevalence of anisometropia in volunteer laboratory and school screening populations
Invest Ophthalmol Vis Sci
Anterior chamber depth, genes and environment. A population study among long-term Greenland Eskimo immigrants in Copenhagen
Acta Ophthalmol (Copenh)
[Biometric data of eyes after the onset of acute glaucoma]
Klin Monatsbl Augenheilkd
Heritability of myopic refractive errors in identical and fraternal twins
Graefes Arch Clin Exp Ophthalmol
Relation between retinal vein occlusions and axial length
Br J Ophthalmol
Infant astigmatism: its disappearance with age
Vision Res
Education and myopia in 110,236 young Singaporean males
Singapore Med J
[Unilateral accommodation spasm: a diagnostic pitfall!]
Klin Monatsbl Augenheilkd
The stages of human development before birth
Refractive error and choroidal perfusion characteristics in patients with choroidal neovascularization and age-related macular degeneration
Ger J Ophthalmol
The change in shape and internal form of the lens of the eye on accommodation
Exp Eye Res
The influence of the size of the lens in ocular disease
Trans Ophthalmol Soc UK 102 Pt
Cataract: the relation between myopia and cataract morphology
Br J Ophthalmol
Déodati F J Ophthal 71: 405–414, 1987, quoting Huron H, Bé;chac: étude de la profondeur de la chambre antérieure
Arch Ophtal (Paris)
Correlation of accommodation between the two eyes
J Opt Soc Amer
Anterior chamber depth in open angle glaucoma
Br J Ophthalmol
Influence of axial length on visual field defects in primary open-angle glaucoma
J Formos Med Assoc
Severe myopia as a risk factor for progressive visual field loss in primary open-angle glaucoma
Ophthalmologica
Long term refractive outcome in eyes of preterm infants with and without retinopathy of prematurity: comparison of keratometric value, axial length, anterior chamber depth, and lens thickness
Br J Ophthalmol
Lens thickness and anglo-closure glaucoma. A comparative oculometric study in South African Negroes and Danes
Acta Ophthalmol (Copenh)
Refractive errors in an urban population in Southern India: the Andhra Pradesh Eye Disease Study
Invest Ophthalmol Vis Sci
Accommodative dysfunction
Doc Ophthalmol
The correlation between intraocular pressure and refractive status
Arch Ophthalmol
Cycloplegic refractions of infants and young children: the axis of astigmatism
Invest Ophthalmol Vis Sci
Major epidemics of the 20th century: from coronary thrombosis to AIDS
J R Stat Soc [Ser A]
Normal values of the accommodation at all ages
JAMA
[Occurrence of changes in the eye in diabetic retinopathy with significant myopia]
Srpski Arh Za Celok Lek
Changes in myopic refractive error with nine months extended wear of hydrogel lenses with high and low oxygen permeability
Optom Vis Sci
Clinical norms for amplitude of accommodation in Chinese
Ophthalmic Physiol Opt
Temperature—a factor in ocular development?
Dev Med Child Neurol
The reciprocal actions of accommodation and convergence
J Physiol
Senile cataract. A comparative study between lens fibre stress and cuneiform opacity formation
Trans Ophthalmol Soc UK
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2023, Contact Lens Practice, Fourth EditionPatients’ attitudes and beliefs to presbyopia and its correction
2021, Journal of OptometryCitation Excerpt :Generally, participants were aware of presbyopia as a ‘natural ageing process’; however, the term ‘presbyopia’ itself was not considered common knowledge. It may be somewhat surprising that the majority of participants were not aware of the term presbyopia or what it meant, despite the epidemiology of presbyopia being 100%.13 Our results are similar to previous work which indicated that there is a general lack of awareness of the topic, which is thought to be one of the main reasons for a 34% prevalence of unmanaged presbyopia even in developed countries.9
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The author reported no proprietary or commercial interest in any product mentioned or concept discussed in this article.
This work has not been funded by anyone.