Are there different types of cataract?
Yes. We will classify the different types of cataracts according to the anatomical zone of the lens in which the cataract appears.
Nuclear cataract : the opacities are located in the nucleus of the lens. Its evolution leads to growing myopia and sometimes the splitting of images.
Cortical cataract : the opacities are located at the periphery, on the cortex of the lens.
Cortico-nuclear cataract : all the layers of the lens are more or less equally clouded. It is the most common form of senile cataract. The patients feel they need more light to see.
Subcapsular cataract : the opacities are located under the posterior or anterior capsule of the lens. This cataract gives the sensation of having a veil before the eyes and of being dazzled.
The different forms of cataracts are also named according to their cause of occurence.
Senile cataract : it is the most common cataract. It appears with ageing, at around 65/70 years old, although it can affect much younger individuals. The nucleus and cortex are opacified (cortoco-nuclear cataract). It often affects far vision first before interfering with near vision.
Traumatic cataract : it often occurs in young people and children following a force trauma (e.g. a punch, champagne cork, ball sports : watch out for badminton and squash!). It is typically posterior subcapsular. It can also follow an eyeball injury or the introduction of a foreign body into the eye. It can sometimes appear long after being hit.
Pathological cataract : they include cataracts alongside another ocular pathology : strong myopia, chronic uveitis (they are called “complicated cataracts”) or to a general metabolic pathology such as insulin-dependent diabetes (posterior subcapsular cataracts) for example. There may be iatrogenic cataracts due to prolonged use of certain drugs (corticosteroids) or in the aftermath of radiation therapy.
Congenital cataract : it can be present from birth (0,03% of births) and requires early management to avoid amblyopia.
Secondary cataract or capsular fibrosis : it occurs frequently after cataract surgery. It is not considered a complication of the first operation. It is due to the clouding of the lens envelope within a few months or years after the primary procedure. It is easily diagnosed with a slit lamp examination and treated at once with the YAG laser (capsulotomy).