Refractive Errors Of A Human Eye
Perfect vision is the result of light passing through a perfectly shaped eye so that it focuses perfectly on the retina. When the eyeball is too long or too short, there is a refractive error, which may be corrected using glasses, contact lenses or refractive surgery (Lasik or Lens Implant).
Refractive Errors – Myopia. When the eye is too long or the cornea is too steep, light is focused in front of the retina. Distant objects appear blurry. Myopia is usually inherited, starting in childhood, with progressive worsening into adulthood.
Refractive Errors – Hyperopia. When the eye is too short or the cornea is too flat, light is focused behind the retina. Near objects appear blurry. In adults, glasses are needed to correct both near and distance vision.
Refractive Errors – Astigmatism. When the cornea is not perfectly spherical, light is focused in a haphazard manner inside the eye, causing distortion. Astigmatism often co-exists with myopia and hyperopia.
Refractive Errors – Childhood Myopia. 80% of the population in Singapore have myopia. Recent studies have shown that myopia in children can be treated with Atropine/Myopine eyedrops which can slow down progression of myopia. Dr Lim’s myopia treatment program uses Atropine eye drops to relax the eye muscles, over a closely-monitored period.
Presbyopia (“Lao Hua”)
Presbyopia develops as the natural crystalline lens in the eye loses its elasticity and can no longer focus clearly on near objects. The need for glasses for reading and close-up tasks usually begins from 40 years of age. Dr Lim treats Presbyopia (“Lao Hua”) with LASIK monovision or multifocal implants.
Authored by: Dr Natasha Lim