REFRACTIVE ERRORS

This is the inability of images to be focused properly on the retina. The most common refractive errors are long
sightedness, short sightedness, presbyopia and astigmatism.

Clinical features

REFRACTIVE ERROR CAUSES CLINICAL FEATURES
Hyperopia, long-sightedness
or far-sightedness, also
termed hypermetropia can
be physiological (axial or
refractive) or pathological
(mal-development,
anatomical or drug-induced)
in nature.
  • Axial etiology (length of the
    eye, small eyes)
  • Refractive etiology (power of
    the eye)
  • Trauma
  • Paralysis of accommodation
  • Blurred vision, eye strain
  • Lazy eye
  • Squint/
  • crossed eye
  • Headaches
Myopia, short-sightedness
or near-sightedness It can be
simple (length and power),
pathological/degenerative
(mal-development or
anatomical) in nature, induced
or pseudomyopia.
  • Axial etiology (length of the
    eye, big eyeball)
  • Refractive etiology (power of
    the eye)
  • Ocular disease, e.g.
    keratoconnus
  • Trauma
  • Blurred distance vision
  • Flashes & floaters (high
    myopia)
  • Asthenopia (eyestrain,
    headaches, etc.)
Presbyopia
It is an age-related visual
impairment. It results from
the gradual decrease in
accommodation expected
with age and can have
multiple effects on quality of
vision and quality of life.
  • Age (35- 40 years)
  • Hyperopia (accommodative
    demand, especially if
    uncorrected)
  • Ocular disease/trauma
    (removal or injury to lens,
    ciliary body or zonules)
  • Systemic diseases (diabetes,
    etc)
  • Drug side-effect
  • Occupation (near vision
    demands)
  • Blurred near vision
  • Difficulty seeing at usual
    near working distance
  • Asthenopia (fatigue, eye
    strain, headaches, etc.)
  • Drowsiness
  • Diplopia (double vision

Investigations

  • History (blurred vision, asthenopia, etc.)
  • Visual Acuity (distance, near and pinhole)
  • Refraction
  • Ocular motility, Binocular Vision and Accommodation
  • Ocular health assessment (slit lamp, fundus assessment)

MANAGEMENT

  • Optical correction with spectacles or contact lenses
  • Vision therapy/orthoptics (for pseudomyopia)
  • For presbyopia: multifocal lenses
  • Refractive Surgery