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
- Look for abormalities of the eye
- Determine visual acuity accurately in both eyes by Snellen chart
- If vision is diminished, (less than 6/12), perform the followingPin hole test
o 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
o Ask the patient to look through this hole at the Snellen chart
o 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 60 cm 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 haemorrhage
- 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 >50 years 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.
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)
- 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
