Summary

A secondary (or complicated) cataract is one that develops as a consequence of pre-existing ocular disease, such as chronic anterior uveitis or acute angle closure glaucoma. Trauma to the eye, either blunt or penetrating, may also result in cataract formation. Ocular trauma is the leading cause of unilateral cataract in young patients.

Secondary cataract

A secondary cataract develops as a complication of a primary ocular pathology, importantly:

• Chronic anterior uveitis
• Acute angle closure glaucoma
• High myopia
• Hereditary fundus dystrophies

The table below summarises the key learning points concerning these ocular diseases and their association with cataract.

• Chronicity and severity of inflammation related to likelihood of cataract formation
• Steroids (topical/systemic) used in management can also cause cataracts
• The first finding is typically a polychromatic lustre on the posterior lens, followed by opacities on the posterior and/or anterior lens | | Acute angle closure glaucoma | -       ‘Glaukomflecken’ (small white-grey anterior subcapsular/capsular opacities) form in the pupillary area, signifying infarcts of the lens epithelium | | High myopia (aka pathological myopia) | -       Associated with posterior subcapsular lens opacity and early-onset nuclear sclerosis (which ironically can worsen the myopia) | | Hereditary fundus dystrophies (e.g. retinitis pigmentosa, Leber congenital amaurosis, gyrate atrophy, Stickler syndrome) | - Usually associated with posterior subcapsular lens opacity
• Cataract surgery is undertaken early, which can improve vision despite the presence of severe retinal changes |

Cataract secondary to medication

Cataract formation can also be caused by medication, such as:

• Topical and systemic steroids may cause cataracts, usually of the posterior subcapsular class. Predominant symptoms are severe glare and reduced near vision ****(see our ‘Age-related cataract’ notes)
• Prolonged chlorpromazine use

Traumatic cataract

Trauma is the most common cause of unilateral cataract in young patients. This causes clouding of the lens at the site of injury (which can develop quickly after the incident), which can extend to the whole lens.

Traumatic cataracts are stellate or flower-shaped.

Aetiology

Traumatic cataracts may be caused by: