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SYMPOSIUM: KERATOCONUS
Year : 2013  |  Volume : 61  |  Issue : 8  |  Page : 382-383

Epidemiology of keratoconus


Gokhale Eye Hospital and Eyebank, Mumbai, Maharashtra, India

Date of Submission16-May-2013
Date of Acceptance04-Jul-2013
Date of Web Publication3-Aug-2013

Correspondence Address:
Nikhil S Gokhale
Gokhale Eye Hospital and Eyebank, Anant building, Gokhale Road (S), Dadar West, Mumbai - 400 028, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0301-4738.116054

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  Abstract 

Prevalence of keratoconus is variable in different parts of the world. Environmental and ethnic factors and the cohort of patients selected for such studies may explain the wide variation in the reported rates. Family history, gender differences, asymmetry in the two eyes, association with ocular rubbing, and natural history of disease are discussed.

Keywords: Epidemiology, keratoconus, prevalence


How to cite this article:
Gokhale NS. Epidemiology of keratoconus. Indian J Ophthalmol 2013;61:382-3

How to cite this URL:
Gokhale NS. Epidemiology of keratoconus. Indian J Ophthalmol [serial online] 2013 [cited 2020 Oct 30];61:382-3. Available from: https://www.ijo.in/text.asp?2013/61/8/382/116054


  Keratoconus Epidemiology Top


Keratoconus has been classically described as a noninflammatory pathology, characterized by a conical shape of the cornea, as a result of thinning and protrusion. The etiopathogenesis is still under research and it may be the final manifestation of diverse pathologic processes. With better understanding of the disease and new imaging modalities as well as the advent of refractive surgery, it is being diagnosed much more often and much earlier than in the past.

The reported prevalence of keratoconus varies widely depending upon the geographic location, diagnostic criteria used, and the cohort of patients selected. The prevalence in studies can range from 0.3 per 100,000 in Russia [1] to 2300 per 100,000 in Central India [2] (0.0003%-2.3%). The first population-based study was done by Hofstetter [3] using a Placido disc and he reported an incidence of 600 per 100,000. The most commonly cited prevalence is 0.054% in Minnesota, USA by Kennedy et al., [4] who used scissors movement on retinoscopy and keratometry for diagnosis.

In Central India, the prevalence of keratoconus was studied based only on the anterior corneal power obtained by keratometry. Prevalence of keratoconus defined as a corneal refractive power ≥48 D was 2.3%. However, the prevalence dropped to 0.6% using a cut off power ≥49 D and 0.1% using a cutoff of ≥50 diopter. [2]

The only other study in literature reporting such a high prevalence was by Millodot et al., [5] in Jerusalem. This videokeratography-based study included only well-defined cases and still reported a prevalence of 2.34% in a college population.

Environmental factors may contribute to the wide variation in prevalence. Geographical locations with plenty of sunshine and hot weather such as India [2] and the Middle East [6] have higher prevalence than locations with cooler climates and less sunshine such as Finland, [7] Denmark, [8] Minnesota, [4] Japan, [9] and Russia. [1] Ultraviolet light induced oxidative stress, which keratoconic corneas cannot handle well, may have a role to play.

Ethnic differences may account for the differences in the reported prevalence of keratoconus. The reports of two surveys in the UK indicated a prevalence 4.4 and 7.5 times greater for Asian (Indian, Pakistani, and Bangladeshi) subjects compared with white Caucasians. [10],[11] These results concur with the higher values of prevalence found in India. [2] In both these studies, it was noted that most of the Asian subjects were Muslim with a high prevalence of consanguinity, a factor usually associated with a high rate of genetic disease.

Family history of keratoconus has been found to be very variable and a high prevalence of keratoconus in a sample population can change the reported rate of a positive family history. It varies between 6% and 10% in most studies, [12] the US Collaborative Longitudinal Evaluation of Keratoconus study reported a rate of 13.5% and a study from Israel where the prevalence is high, reported a rate of 21.74%. [13]

Keratoconus affects both genders, although it is unclear whether significant differences between males and females exist. Some studies have not found differences in the prevalence between genders; [4],[14] others have found a greater prevalence in females, [12] while other investigators have found a greater prevalence in males. [11],[15],[16]

In two studies from North India [17],[18] and one from Western India, [19] keratoconus was noted more often in males, while the Central India study found a higher prevalence in women. [2]

A higher prevalence of keratoconus has been found in patients with eye rubbing. Ocular rubbing associated with atopy, ocular allergies, Down's syndrome, and tapetoretinal degenerations have a higher incidence of keratoconus. [12]

Keratoconus usually occurs bilaterally but asymmetry is common. In a large series, 14.3% had unilateral disease. [20] Although unilateral cases do exist; their frequency might be even lower than reported, if appropriate diagnostic criteria and examination techniques that detect very early keratoconus are used. [21]

The natural history of disease is variable. Typically at about the age of puberty, the keratoconic process starts and usually, over a period of next 10-20 years, the process continues until the progression gradually stops. The severity of the disorder at the time the progression stops can range from very mild irregular astigmatism to severe thinning, protrusion, and scarring requiring keratoplasty. [12] Keratoconus in India presents at a younger age than in the Western population and progresses more rapidly. [22] Earlier age of onset has been associated with a significantly higher need for surgery possibly because of more rapid progression. [18]

 
  References Top

1.
Gorskova EN, Sevost'ianov EN. Epidemiology of keratoconus in the Urals. Vestn Oftalmol 1998;114:38-40.  Back to cited text no. 1
[PUBMED]    
2.
Jonas JB, Nangia V, Matin A, Kulkarni M, Bhojwani K. Prevalence and associations of keratoconus in rural Maharashtra in central India: The central India Eye Medical Study. Am J Ophthalmol 2009;148:760-5.  Back to cited text no. 2
[PUBMED]    
3.
Hofstetter HW. A keratoscopic survey of 13,395 eyes. Am J Optom Arch Am Acad Optom 1959;36:3-11.  Back to cited text no. 3
[PUBMED]    
4.
Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and epidemiological study of keratoconus. Am J Ophthalmol 1986;101:267-73.  Back to cited text no. 4
[PUBMED]    
5.
Millodot M, Shneor E, Albou S, Atlani E, Gordon-Shaag A. Prevalence and associated factors of keratoconus in Jerusalem: A cross-sectional study. Ophthalmic Epidemiol 2011;18:91-7.  Back to cited text no. 5
[PUBMED]    
6.
Assiri AA, Yousuf BI, Quantok AJ, Murphy PJ. Incidence and severity of keratoconus in Asir province, Saudi Arabia. Br J Ophthalmol 2005;89:1403-6.  Back to cited text no. 6
    
7.
Ihalainen A. Clinical and epidemiological features of keratoconus genetic and external factors in the pathogenesis of the disease. Acta Ophthalmol Scand 1986;178(Suppl):S5-64.  Back to cited text no. 7
    
8.
Nielsen K, Hjortdal J, Aagard NE, Niels E. Incidence and prevalence of keratoconus in Denmark. Acta Ophthalmol Scand 2007;85:890-2.  Back to cited text no. 8
    
9.
Tanabe U, Fujiki K, Ogawa A, Ueda S, Kanai A. Prevalence of keratoconus patients in Japan. Nihon Ganka Gakkai Zasshi 1985;89:407-11.  Back to cited text no. 9
[PUBMED]    
10.
Georgiou T, Funnell CL, Cassels-Brown A, O'Connor R. Influence of ethnic origin on the incidence of keratoconus and associated atopic diseases in Asian and white patients. Eye (Lond) 2004;18:379-83.  Back to cited text no. 10
    
11.
Pearson AR, Soneji B, Sarvananthan N, Sandforth-Smith JH. Does ethnic origin influence the incidence or severity of keratoconus? Eye (Lond) 2000;14:625-8.  Back to cited text no. 11
    
12.
Krachmer JH, Feder RS, Belin MW. Keratoconus and related non-inflammatory corneal thinning disorders. Surv Ophthalmol 1984;28:293-322.  Back to cited text no. 12
[PUBMED]    
13.
Zadnik K, Barr JT, Edrington TB, Everett DF, Jameson M, McMahon TT, et al. Baseline findings in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) study. Invest Ophthalmol Vis Sci 1998;39:2537-46.  Back to cited text no. 13
[PUBMED]    
14.
Li X, Rabinowitz YS, Rasheed K, Yang H. Longitudinal study of the normal eyes in unilateral keratoconus patients. Ophthalmology 2004;111:440-6.  Back to cited text no. 14
[PUBMED]    
15.
Owens H, Gamble G. A profile of keratoconus in New Zealand. Cornea 2003;22:122-5.  Back to cited text no. 15
[PUBMED]    
16.
Wagner H, Barr JT, Zadnik K. Collaborative longitudinal evaluation of keratoconus (CLEK) study: Methods and findings to date. Cont Lens Anterior Eye 2007;30:223-32.  Back to cited text no. 16
[PUBMED]    
17.
Fatima T, Acharya MC, Mathur U, Barua P. Demographic profile and visual rehabilitation of patients with keratoconus attending contact lens clinic at a tertiary eye care centre. Cont Lens Anterior Eye 2010;33:19-22.  Back to cited text no. 17
[PUBMED]    
18.
Sharma R, Titiyal JS, Prakash G, Sharma N, Tandon R, Vajpayee RB. Clinical profile and risk factors for keratoplasty and development of hydrops in north Indian patients with keratoconus. Cornea 2009;28:367-70.  Back to cited text no. 18
[PUBMED]    
19.
Agrawal VB. Characteristics of Keratoconus patients at a tertiary eye center in India. J Ophthalmic Vis Res 2011;6:87-91.  Back to cited text no. 19
  Medknow Journal  
20.
Amsler M. Some data on the problem of keratoconus. Bull Sot Belge Ophthalmol 1961;129:331-54.  Back to cited text no. 20
    
21.
Chopra I, Jain AK. Between eye asymmetry in keratoconus in an Indian population. Clin Exp Optom 2005;88:146-52.  Back to cited text no. 21
[PUBMED]    
22.
Saini JS, Saroha V, Singh P, Sukhija JS, Jain AK. Keratoconus in Asian eyes at a tertiary eye care facility. Clin Exp Optom 2004;87:97-101.  Back to cited text no. 22
[PUBMED]    



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