Refractive Errors

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This is a condition where one presents with poor vision either at near or distance at any age. There  are mainly 4 types of refractive errors namely presbyopia, myopia, astigmatism and hyperopia. A  patient may have more than one type of refractive error.

Presbyopia

This is a disorder of refractive status commonly occurring in older people. 

Clinical presentation

  • It usually starts after the age of 40 years
  • The main complaint is difficulty in reading/writing or doing near works
  • Diagnosis is only through refraction. Attendance to heath facility is also a good opportunity for screening of glaucoma and diabetic retinopathy

Investigations 

  • Visual acuity
  • Tonometry
  • Fundoscopy

Non-pharmacological Treatment

  • Convex lens spectacles for near vision. 

 

Myopia (Short sightedness)

This is a condition whereby patient has difficulty seeing far objects.

Clinical presentation 

  • It is common in young age between 5–25 years
  • The  condition  persists  throughout life

Investigations 

  • Visual acuity
  • Refraction
  • Fundoscopy
  • Stereopsis test

Non-pharmacological Treatment 

  • Concave lens spectacles for constant wear

  • If not treated early, it may progress rapidly and lead to retinal complications

  • It is diagnosed through refraction.

  • Colour

  • Strabismus assessment in all children

Hypermetropia (Long sightedness)

This  is  a  condition  where  patients  have  difficulty  in  seeing  near  objects.  It  is  less  manifested  in  children as they have a high accommodative power.  

Clinical presentation 

  • Ocular strain
  • Diagnosis in children should be reached after refraction through a pupil that is dilated

Investigations 

  • Visual acuity
  • Refraction
  • Fundoscopy
  • Stereopsis test

Non-pharmacological Treatment 

  • Convex lens spectacles for constant wear 

Note: Spectacles should be given to:

  • Children who have only significant hypermetropia (more than +3.00 Diopter of Sphere both eyes), all children who present with squint and have significant hypermetropia and children with anisometropia
  • Elderly who present with signs of ocular strain

Astigmatism

This is a condition where the cornea and sometimes the lens have different radius of curvature in all  meridians  (different  focus  in  different  planes).  Some  myopic  and  hyperopic  patients  may  have  astigmatism.  

Clinical Presentation 

  • Poor vision at distance,
  • Photophobia
  • Headache (sometimes).
  • Diagnosis is reached through refraction

Investigations

  • Visual acuity
  • Refraction
  • Fundoscopy
  • Stereopsis test
  • Colour
  • Strabismus assessment in all children

Non-pharmacological Treatment  

  • Cylindrical lenses spectacles for constant wear

Note: 

  • Reassessment for all types of refractive errors is done annually and change the spectacles of there are significant variation and improvement with new correction.
  • All  children  with  rapid  progression  of  refractive  errors  need  to  be  seen  by  Paediatric Optometrist and Paediatric Ophthalmologist for further assessment