Myopia or nearsightedness is globally concerning due to its high prevalence and incidence. In fact, more than 28.3% of the earth population are myopic, and it’s expected to reach 50% in 2050. Actually, this condition is characterized by axial length elongation (eye longer than the normal) or powerful lens, where the image of an object focuses in front of the retina, not at the retina. Therefore, a myopic person tends to see near objects clearly, while far objects look blurry. This is totally different from normal sight where the image is focused normally on the retina.
What causes myopia?
Frankly, the reason behind the massive prevalence of myopia is still not clear. Although genetics (family history) is a major cause, it doesn’t explain the increase of the disease. Consequently, the cause is a combination of genetic, environmental, pathologic or toxic factors.
- Genetically: having one or two myopic parents is an important cause.
- Environmentally: education duration, excessive near work are all responsible for myopia.
- Pathologically: diabetes, cataracts, or keratoconus might cause permanent or provisional myopia.
- Toxically: by toxic substance consumption leading to troubled vision temporary or permanently.
Symptoms:
Without doubt, myopia starts at childhood and develops with aging through teens to stabilize after the age of 18. Also, it might be combined with other vision conditions such as presbyopia or astigmatism.
- Far objects are seen blurry
- Inability to drive especially at night
- Eyestrain
- Over blinking
- Headaches or migraines
- Squinting excessively to see better
- Rubbing eyes frequently
Types of myopia:
- Simple myopia of less than 6 diopters (D). In fact, it stabilizes at 18-20 years of age and must be corrected by glasses, contact lenses or surgery.
- High, pathologic or magna myopia of more than 6-8 diopters (D). To clarify, it results from extreme axial eye length elongation mostly at the retina level. Indeed, this is a concerning type since it causes vision impairment and a specialist must evaluate it often.
Diagnosis:
Eye examining in the major approach to diagnose myopia, and it may affect one eye or both.
- Refraction examination
- Intraocular pressure measurement
- Visual acuity
- retina examination (fundus)
- color perception
- strabismus (lazy eye) check by eye movement analysis
- Penetration of color testing
- Checking for binocular vision
Notably, glaucoma and myopia structural and functional defects can be very confusing and indistinguishable. Hence, only longitudinal observation is qualified to distinguish them apart. Indeed, myopic children testing must be at the age of 3 and later every 2 school years. While adults at risk must be tested often (every year).
Treatment:
The most effective counter methods are glasses, outdoor activities, defocusing contact or corrective lenses, orthokeratology, and low-dose atropine pharmaceutical measurements. Besides, myopia suppressive gene (EGR1) can be upregulated by violet light (VL); thus, lenses that are transmissible to VL prevent the progression of the disease best. Moreover, surgeries such as Lasik and intraocular lens can be done to enhance vision.
High myopia complications:
Pathologic complications, vision-related life quality and specific contact lens complications are firmly correlated with high myopia. As a matter of fact, myopia is the 6th leading cause of blindness. As a result, some complications are:
- Formation of cataract where the eye lens is cloudy
- Retinal detaches from peripheral retinal tears
- Macular hole which opens at the retina center
- Dome-shaped macula
- Peripapillary deformation resulting in depression in some areas or grooves
- Myopic foveoschisis (schisis-like retina thickening)
- Choroidal or scleral thinning
- Glaucoma which damages the optic nerve
- Myopic choroidal neovascularization
References:
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-Hopf S, Pfeiffer N. Epidemiologie der Myopie [Epidemiology of myopia]. Ophthalmologe. 2017 Jan;114(1):20-23. German. doi: 10.1007/s00347-016-0361-2. PMID: 27601149.
-Jones D, Luensmann D. The prevalence and impact of high myopia. Eye Contact Lens. 2012 May;38(3):188-96. doi: 10.1097/ICL.0b013e31824ccbc3. PMID: 22495679.
-Cooper J, Tkatchenko AV. A Review of Current Concepts of the Etiology and Treatment of Myopia. Eye Contact Lens. 2018 Jul;44(4):231-247. doi: 10.1097/ICL.0000000000000499. PMID: 29901472; PMCID: PMC6023584.
-Chang RT, Singh K. Myopia and glaucoma: diagnostic and therapeutic challenges. Curr Opin Ophthalmol. 2013 Mar;24(2):96-101. doi: 10.1097/ICU.0b013e32835cef31. PMID: 23542349.
-Torii H, Kurihara T, Seko Y, et al. Violet Light Exposure Can Be a Preventive Strategy Against Myopia Progression. EBioMedicine. 2017; 15:210-219. doi: 10.1016/j.ebiom.2016.12.007
-Bremond-Gignac D. Myopie de l’enfant [Myopia in children]. Med Sci (Paris). 2020;36(8-9):763-768. doi:10.1051/medsci/2020131
