Visual Problems

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Visual problems may be due to refractive errors, damage to the eye or optic nerve. This may be an indication of underlying diseases such as diabetes or hypertension.

Investigations

  • Assess ocular alignment
  • Determine visual acuity accurately in both eyes by Snellen chart

If vision is diminished, (less than 6/12), perform the following:

  • Pin hole test
    • Make a hole of about 1mm wide in a piece of dark/black paper – you can push a hole in a paper or card with a pen tip
    • Ask the patient to look through this hole at the Snellen chart
    • If vision improves, this means that the patient has a refractive error
  • Red Reflex Test
    • The patient looks past the examiners head focusing on a distant target.
    • With the ophthalmoscope at 0 (zero) the examiner keeps close to his eye and then focuses the beam of light so that it falls on the pupillary area of the cornea
    • The examiner stands about 60cm away from the patient.
    •  In normal individuals, the examiner should be able to see a red or pink colour (reflex) through the pupil which comes from the retina.

Significance of absent red reflex  

If there is history of trauma or diabetes, the absence of a red reflex is probably due to: 

  • Retinal detachment
  • A vitreous hemorrhage
  • Mature cataract

If there are cataracts, one usually sees: 

  • Black shadows against the red reflex in immature cataract, or
  • Absence of red reflex in mature cataracts

In a >50years of age with no history of trauma, diabetes or previous eye disease, an absent red reflex is often due to cataract formation, especially with decreased visual acuity. 

Fundoscopy 

Note : Associated diabetes or hypertension should be adequately managed with referral, as surgery can only be considered with appropriately managed systemic disease 

Referral 

Urgent within 12–24 hours 

  • Sudden loss of vision in one or both eyes
  • Pain or redness in one eye only especially with visual and pupillary abnormalities
  • Recent proptosis of one or both eyes or enlargement of the eye (buphthalmos) in children
  • Hazy cornea in children
  • Unilateral watery eye

Within days 

  • Squint of recent onset
  • Suspected or previously diagnosed glaucoma
  • Double vision following recent injury might indicate orbital fracture
  • Leukocoria (white reflex from the pupil) especially in children
  • Squint at an age if not previously investigated by ophthalmologist
  • Visual loss in patients with systemic disease such as diabetes

Non-urgent referral 

  • Cataracts in adults
  • Refractive errors in teenage and adults
  • Longstanding blindness–first visit to health facility