Myopia (Short-Sightedness)

What is Myopia (Short-Sightedness)?

Myopia, or short-sightedness, is the most common refractive error worldwide and its prevalence is increasing rapidly, particularly in young people. It occurs when the eyeball is slightly too long from front to back, causing light to focus in front of the retina rather than on it. Distant objects appear blurred while near objects are seen clearly. High myopia (greater than -6 dioptres) is associated with an increased risk of retinal complications including retinal detachment, macular degeneration and glaucoma.

Symptoms

• Difficulty seeing distant objects clearly — road signs, blackboards, TV screens
• Clear vision for reading and close work
• Squinting to try to see at distance
• Headaches from the effort of trying to focus
• Eye strain, particularly after driving

Causes

• Excessive axial length of the eyeball — the most common mechanism
• Steeper-than-normal corneal curvature
• Strong genetic component — risk significantly increased if one or both parents are myopic
• Environmental factors — prolonged near work and limited outdoor time in childhood

Diagnosis

Refraction assessment, measuring glasses prescription. Cycloplegic refraction (with dilating drops) is used in children to obtain an accurate measurement. Axial length measurement and fundus examination are important in high myopia.

Treatment

Spectacles and contact lenses are the standard correction. Orthokeratology (overnight contact lenses) and low-dose atropine drops are established myopia control strategies in children. In adults, laser vision correction (LASIK, LASEK) or implantable collamer lenses (ICL) can reduce or eliminate glasses dependence. People with high myopia should have annual dilated fundus examinations.