A cataract is an opacification of the lens of the eye that can be congenital or acquired later in life. The lens is made up of three components: the capsule, cortex, and nucleus. Congenital cataracts are often bilateral and genetic in nature, while acquired cataracts are usually age-related but can be caused by diseases like diabetes, sunlight exposure, or trauma. Cataracts can cause vision loss and are typically treated by surgically removing the opaque lens.

1. Cataracts
The crystalline lens is a transparent, biconvex structure in the eye that, along
with the cornea, helps to refract light to be focused on the retina. A cataract is an
opacification of the lens of the eye; it is one of the leading causes of blindness in
the world and it may be congenital or more commonly acquired.
The Anatomy of the Lens
The lens is made up of three components
 Capsule – smooth, transparent basement membrane that completely
surrounds the lens
 Cortex – made up of zonula fibres
 Nucleus – the maximal area for refraction in the lens
Congenital Cataracts
 Two thirds of congenital cataracts are bilateral
 Bilateral cataracts tend to be genetic and most are autosomal dominant
 Congenital cataracts may also follow an autosomal recessive or X-linked
recessive pattern
 Unilateral congenital cataracts tend to be sporadic
 Other causes of congenital cataract include metabolic disorders (e.g.
galactosemia), intrauterine infection (e.g. rubella, cytomegalovirus,
toxoplasmosis and varicella), chromosomal (e.g. Down’s Syndrome)
o/e
 Irregular red reflex is detected at the initial screening
Ddx
 Retinoblastoma
Ix
 TORCH screen
 FBC
 Urine for reducing substances of metabolism and amino acids

2.  CT brain scan
 Hearing tests
Tx
 Cataract is removed by phacoemulsification at 4-6 weeks to prevent
amblyopia
 Glasses or contact lenses may be needed later in life to correct vision
 If unilateral physical occlusion of the bad eye or atropine penalisation of
the stronger eye can prevent amblyopia
Acquired Cataracts
 Most common cause of cataract is natural ageing
 May be secondary to systemic diseases such as; diabetes, muscular
dystrophy, neurofibromatosis or atopic dermatitis
 May also occur secondary to ocular diseases such as; chronic anterior
uveitis, high myopia, fundus dystrophy or acute angle closure glaucoma
 Exposure to sunlight, cigarette smoke, radiation, chronic dehydration,
corticosteroids and antipsychotics also increase the likelihood to acquire
cataracts
o/e
 Patients complain of reduced visual acuity, increased glare in low light,
myopic shift and diplopia
Ddx
 Traumatic Cataract
Ix
 Direct and indirect ophthalmoscopy
 Check for co-morbidities such as diabetes
Tx
 Treatment of choice is phacoemulsification
 Indications for surgery include low visual acuity impacting on activities of
daily living
 An appropriate artificial lens is inserted into the preserved capsule
during the operation
 Although vision will be good, this artificial lens can not accommodate
therefore spectacles are needed for near vision
Traumatic Cataracts
 Most common cause of acquired unilateral cataracts in the young
 Cataracts produced tend to be irregularly shaped and colourful
 Caused by; penetrating trauma, blunt trauma, electricity and
infrared/ionizing radiation.
 Managed conservatively unless the cataract obstructs field of vision
 If the capsule is no longer intact phacoemulsification is contraindicated