Some types of congenital cataract are visually significant, affecting the child’s vision, while others are milder and have no effect on the vision. If addressed early, congenital cataract is usually treatable.
Today we will talk about the different types of congenital cataract, highlighting the properties and characteristics of each type, and the predisposing factors that lead to development of that particular type. Before starting with our topic, it is important to remember the example that we discussed before about the composition of the human lens.
The human lens is composed of an outer layer or a coat called the “lens capsule”, surrounding a core of transparent lens fibers and cells forming the core of the lens. Now, I want to add one small detail to that description which is the presence of another layer inside the inner layer (like the “hazelnut” of an M&Ms Chocolate button). This innermost layer is the nucleus of the human lens.
After this brief description of the composition of the human lens, let’s get back to our topic, and discuss the different types of congenital cataract.
The lamellar cataract
This is the most common type of all the types of congenital cataract. It is characterized by being bilateral and symmetric. This type of cataract is inherited in some cases. In this condition, you find a history of cataract disseminating through many generations in the same family.
Sometimes, this type of cataract is due to the exposure of the mother to a toxic material during the period of pregnancy in which the lens of the baby is being formed.
The lamellar cataract appears as a well-defined disc-shaped opacity that is equal in size and density in both eyes. This gives the child a distinct appearance of a disc-shaped white opacity inside the pupil.
The effect of this type of cataract on the vision depends on the size and the density of the lens opacity.
The polar cataract
This type of congenital cataract can be classified into 2 subtypes:
- anterior polar cataract
- posterior polar cataract.
The anterior polar cataract is characterized by being bilateral and symmetric in most cases. Theses cataracts are usually small and non-progressive, but they are commonly associated with other ocular abnormalities. This type of cataract doesn’t affect vision and doesn’t require treatment.
The posterior polar cataract is completely different from anterior polar cataract. It is usually large in size and situated near the center of the lens. This type of cataract usually affects vision because of its large size and centered position.
Posterior polar cataracts can be either single sporadic cases or inherited. In sporadic cases, the cataract is usually unilateral. In inherited cases, the cataract tends to be bilateral.
The cerulean cataract
This type of congenital cataract is also known as blue dot cataract because it forms small bluish opacities inside the lens. It is non-progressive and doesn’t affect vision and doesn’t require treatment.
The nuclear cataract
This type of congenital cataract involves opacification of the nucleus of the lens (the “hazelnut”). This type of cataract is usually bilateral. The severity of the cataract depends on the degree of opacification.
The sutural cataract
This type is also known as the stellate cataract. These cataracts appear as longitudinal opacities having branches. This type of cataract is usually bilateral and symmetric. It usually is genetically inherited.
This type of cataract doesn’t affect vision and doesn’t require treatment.
The coronary cataract
This type of cataract is composed of multiple small opacities arranged around the equator of the lens, like a crown. This type of cataract can’t be seen except after dilating the pupil. It usually has familial inheritance. This type of cataract also doesn’t affect vision and doesn’t require treatment.
The capsular cataract
This type of cataract entails opacification of the lens capsule (the colorful outer coat of the candy button). This cataract doesn’t affect vision and doesn’t require treatment.
The complete cataract
In this type of cataract, all the transparent lens fibers are opacified. This cataract can be unilateral or bilateral.
Some cataracts might be subtotal or incomplete at birth, but they usually change rapidly to total or complete cataracts in a short period of time after birth. This cataract has the worst effect on vision amongst all the types of congenital cataract.