Cataract is the clouding of the natural lens in the eye. It is most commonly due to ageing but can also be caused by trauma, illness (such as diabetes), or even congenital (from birth). It occurs when there is a disruption to the fine arrangement of the lens protein. When the lens gets cloudy, it reduces the amount of light entering the eye, hence causing a decrease in vision. Cataract is the leading cause of preventable blindness globally; if untreated, it can lead to blindness.
In this article, we will share on a rare form of congenital cataract known as cerulean cataract.
Cerulean cataract (also known as ‘blue-dot’ cataract) occurs where there are blue-white opacities in the lens cortex (middle layer of the lens). It can develop during childhood or occur at birth (congenital). The cause of cerulean cataract is due to mutation of several genes. It is of autosomal dominant inheritance (i.e. an affected individual has a copy of the mutant gene and a normal gene on a pair of non-sex chromosomes). The cataract can develop in 1 or both eyes and is progressive. Visual acuity is well-preserved, and surgery is usually not required before adult life.
Infants with cerulean cataract may be asymptomatic depending on the severity of the opacities. If severe, complications such as nystagmus (rapid involuntary movement of the eyes) and amblyopia (lazy eye) can develop. Both male and female can be equally affected. Family history of congenital cataract is one of the risk factors.
No treatment can prevent cerulean cataract from developing or progressing, but surgery may be required to prevent amblyopia (depending on severity of cataract at point of diagnosis and age of patient).
Surgery is usually not warranted until the 2nd to 4th decade of life. The need for surgery depends on the visual impact. Like all cataract removals, treatment of cerulean cataract is through cataract surgery. There are 2 types of modern-day cataract surgery techniques: micro-incision phacoemulsification and laser-assisted cataract surgery. The surgery cost varies and is dependent on factors including seniority of the eye surgeon, type of intraocular lens implanted (eg monofocal, multifocal), anaesthetist fee, facility fees etc. Most people can achieve good post-surgery outcomes.
Genetic counselling is usually straightforward if the cerulean cataract is congenital, bilateral, the abnormality is limited to the lens and the presence of a family history. If the cataract is unilateral (only in 1 eye), the cause is usually non-genetic. If the cataract is bilateral with no family history, further investigations will be required. Firstly, the child’s immediate family (both parents and siblings) will have to undergo dilated eye examinations to exclude congenital cataract. If immediate family has been excluded, the child needs to be examined by the paediatrician to rule out any other multisystem disorder associated with cataract through a series of investigations. If investigations are normal and in the absence of family history, the risk of recurrence in subsequent pregnancies is extremely low.
Regular eye examination
Cerulean cataract is a progressive condition that starts from childhood. It is thus advisable to attend regular eye examination to prevent amblyopia from developing, monitor the progression of condition and for early intervention should the need arise.