Symptoms and causes

Symptoms and causes

What is it?

In the eye, the lens is located behind the pupil and behind the iris. The lens is surrounded by a very thin cover and hangs in the inside of the eye with very fine fibres. Normally, the lens of the eye is completely transparent, but when it becomes clouded we speak of a cataract. Usually, a cataract is a consequence of ageing. Other causes are medication (including cortisone), diabetes, heredity, trauma, eye infections, congenital... A cataract usually develops on both eyes and can evolve slowly or rapidly. It usually does not evolve evenly and varies from eye to eye and from patient to patient.


Vision impairment due to cataracts Patients complain of blurred vision, fog in front of their eyes, the impression of looking through a frosted glass or that their glasses are always dirty. Reading is hard, and it is difficult to recognise people from a distance. Some patients are severely hindered by bright sunlight and sometimes even see double.

When a cataract develops into a total cataract, patients can only see the difference between light and dark. The pupil is greyish-white.

Diagnosis and treatment

Diagnosis and treatment


During a visit, the ophthalmologist diagnoses a cataract with the slit lamp or a biomicroscope. This way, the severity of the cataract can be determined and its evolution monitored. There are different types of cataracts, depending on their location:

  • nuclear: obfuscation of the central lens core
  • cortical: obfuscation of the cortex
  • total: clouding of the entire lens


More information about cataract treatment can be found on the page cataract surgery.


Treatment centres and specialisations

Treatment centres and specialisations
Eye Clinic

Latest publication date: 17/05/2023
Supervising author: Dr Vanwynsberghe David