Refers to any abnormality in the focusing mechanism of the eye

Definitions

• Emmetropia: no refractive error, light focussed onto retina
• Ametrophia: retractive error present, light focussed in front of retina or behind retina
• Anisometrophia: significant difference between right and left ametropia

Myopia (short-sightedness)

Pathophysiology

• Abnormally increased axial length of eye or, less commonly, increased refraction means light focuses in front of the retina

Clinical features

• Clear near vision, blurred far vision

Management

• Glasses with concave (negative) lenses

Complications

• Complications related to larger eyeball size
  • Retinal detachment
  • Primary open-angle glaucoma

Hyperophia (far-sightedness)

Pathophysiology

• Abnormally decreased axial length of eye means light focuses in behind the retina

Clinical features

• Blurred near vision, clear far vision