Eye Health

Updated 26 September 2018

Diagnosing cataracts

An ophthalmologist will perform an eye examination to determine whether or not cataracts are present.

The diagnosis of cataract is primarily based on a medical history and an eye examination. Vision problems are compared with the results of an eye examination and visual acuity tests to:

  • Confirm the presence of cataracts
  • Rule out other conditions that may cause vision loss

Your healthcare practitioner can see the abnormal lens with a hand-held viewing instrument called an ophthalmoscope.

Note that the usual test for visual acuity, the letter eye chart, may not reflect the true nature of visual loss. Other tests, which measure glare sensitivity, contrast sensitivity, night vision, colour vision, and side or central vision, can help with the diagnosis.

Should your doctor find a cataract, he or she can monitor it and advise you on future treatment.

During the diagnostic examination, an ophthalmologist will measure the shape, size and general health of the eye to determine whether a lens implant will be effective.

Infants are checked for cataracts at birth and during routine visits to health professionals, or parents may detect cataracts in an infant by noticing a white pupil or poor vision in their child.

If cataracts are suspected in an infant or a child, he or she should immediately be referred to an ophthalmologist for evaluation and treatment.

Reviewed by ophthalmologist Dr Viresh Dullabh, MBBCh (Wits) FC Ophth SA (CMSA) MMED (UKZN). September 2018.

Read more:

Symptoms of cataracts

Treating cataracts

Preventing cataracts


Ask the Expert


Megan Goodman qualified as an optometrist from the University of Johannesburg. She has recently completed a Masters degree in Clinical Epidemiology at Stellenbosch University. She has a keen interest in ocular pathology and evidence based medicine as well as contact lenses.

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