September 1, 2020
By Dwight Akerman, OD, MBA, FAAO, FBCLA
Is myopia a simple refractive error or a disease? This is an important question because the answer will influence our approach to managing myopia.
Consider the following definitions of disease:
- A disease is any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and differing in nature from physical injury. (Encyclopedia Britannica, 2020)
- A disease is an abnormal condition affecting a living organism. Diseases are generally understood to be medical conditions that involve a pathological process associated with a specific set of symptoms. (Infectious Disease News, 2019)
Clinical trials and work with animal models of myopia have provided ample evidence that axial elongation is the primary factor driving myopic progression. Indeed, refractive myopia, in which the optical power of the cornea and/or lens is abnormally high in eyes with a normal axial length, also exists. However, refractive myopia is far less common than axial myopia.
When comparing interventions to reduce myopic progression, there is a clear relationship between the impact of an intervention on refraction and axial length.1 Ocular morbidity increases per diopter and per millimeter of axial length, thus increasing the risk of serious, sight-threatening complications:
|myopic maculopathy3||2.2 X higher||9.7 X higher||40.6 X higher||126.8 X higher|
|retinal detachment4||3.1 X higher||9.0 X higher||21.5 X higher||44.2 X higher|
|PSC cataract5||1.6 X higher||3.2 X higher||5.4 X higher||12.3 X higher|
|glaucoma6||1.7 X higher||2.5 X higher||2.5 X higher||N/A|
Odds Ratio of Ocular Disease as a Function of Myopia Relative to Emmetropia2
Bullimore and Brennan showed that a one diopter increase in myopia is associated with a 67 percent increase in the prevalence of myopic maculopathy. Furthermore, slowing myopia by one diopter reduces the likelihood of a patient developing myopic maculopathy by 40 percent. This treatment benefit accrues regardless of the level of myopia.7
Based on these definitions and data, I believe myopia should be considered as a disease rather than merely a refractive error.
Best professional regards,
Dwight H. Akerman, OD, MBA, FAAO, FBCLA
Chief Medical Editor
- Huang J, Wen D, Wang Q, et al. Efficacy comparison of 16 interventions for myopia control in children: a network meta-analysis. Ophthalmology. 2016; 123: 697–708.
- Flitcroft, D. I. (2012). The complex interactions of retinal, optical, and environmental factors in myopia aetiology. Progress in retinal and eye research, 31(6), 622-660.
- Vongphanit, J., Mitchell, P., & Wang, J. J. (2002). Prevalence and progression of myopic retinopathy in an older population. Ophthalmology, 109(4), 704-711.
- Ogawa, A., & Tanaka, M. (1988). The relationship between refractive errors and retinal detachment–analysis of 1,166 retinal detachment cases. Japanese journal of ophthalmology, 32(3), 310-315.
- Chang, M. A., Congdon, N. G., Bykhovskaya, I., Munoz, B., & West, S. K. (2005). The association between myopia and various subtypes of lens opacity: SEE (Salisbury Eye Evaluation) project. Ophthalmology, 112(8), 1395-1401.
- Marcus, M. W., de Vries, M. M., Montolio, F. G. J., & Jansonius, N. M. (2011). Myopia as a risk factor for open-angle glaucoma: a systematic review and meta-analysis. Ophthalmology, 118(10), 1989-1994.
- Bullimore, M. A., & Brennan, N. A. (2019). Myopia control: why each diopter matters. Optometry and Vision Science, 96(6), 463-465.