Dr Ben Wild
Overview |
As our bodies develop from birth until adulthood, our eyes have to change in lock-step. This process is called emmetropization (where the growth of the eye matches the change in focusing power). Most of the focusing power of the eye comes from the cornea, the clear tissue in front of the colored iris, and the intra-ocular lens, a clear tissue located through the pupil.
A sagittal view of an eye with light rays focusing perfectly on the retina.
Myopia, or nearsightedness, occurs when the cornea and the lens focus light before the retina (the back surface of the inside of the eye responsible for sensing light). This is usually due to the eye growing too quickly or growing too large. Someone with myopia notices that distant objects are blurry without glasses. Unfortunately the incidence of myopia is skyrocketing.
A sagittal view of a myopic eye with light rays focusing in front of the retina (top) and a view of a myopic eye with glasses that are helping focus the light on the retina (bottom).
Signs and Symptoms |
Signs
Poor vision without glasses, squinting.
Symptoms
Eyestrain, headaches, difficulty seeing distant objects.
Causes and Risk Factors |
Causes
Mismatch between the growth of the eye and focusing power of the cornea and lens.
Risk Factors
Parents with myopia, East Asian descent, large amounts of time doing near work (screens, books, etc.), urban living, higher education, limited outdoor time.
Prevention and Treatment |
Prevention
Research is needed and is currently investigating potential risk factor targets. Currently, having at least 2 hours per day of outdoor time has been shown to be preventative.
Treatments
· Myopia management is essential for young patients (myopes under 16 years of age).
o Atropine drops lower myopia progression by about 70%.
o Myopia control glasses lower myopia progression by about 65%.
o Myopia control soft contact lenses lower myopia progression by about 65%.
o Orthokeratology contact lenses lowers myopia progression by about 65%.
· Hard contact lenses that are worn while sleeping, reshape the front of
the eye, and correct myopic prescriptions.
· Glasses.
· Contact lenses (soft, hard, and orthokeratology).
· Laser eye surgery.
Prognosis |
In most cases, myopia does not cause blindness and vision can be corrected with simple tools like glasses, contacts or laser eye surgery. However, the higher the myopia, the higher the risk of conditions like early cataracts, glaucoma, macular degeneration and retinal detachments. In fact, any amount of myopia increases odds of getting glaucoma by about 50% and early cataracts by 18%. Mild myopia (between -0.50 and -3.00) has a 320% higher chance of retinal detachments and 136% chance of myopic macular degeneration whereas high myopia (over -6.00) has a 1260% higher chance of retinal detachments and 8460% chance of myopic macular degeneration. Luckily, the earlier myopia is detected and the earlier myopia control is started, the lower the myopia will become and the lower the odds of developing vision threatening eye conditions.
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