Types of Cataract: What are the Differences in Causes?

Having cataracts will definitely affect your day-to-day life, and it can progressively get worse if not addressed. Learn about the different types of cataract here.

How Do Cataracts Affect One’s Vision?

For us to be able to see clearly, light has to enter our eyes and reach the layers at the back of the eye responsible for sending signals to our brain for vision. The lens, a transparent gel-like body inside the eye, focuses light to the back of the eye. It focuses light by changing its curvature. The lens’s ability to change its form is what allows us to see objects clearly at different distances.

In people with cataracts, there is sclerosis or hardening of the lens. When hardening happens, the lens is unable to adjust appropriately causing vision problems. The hardened part of the lens also stops light from passing through the eye, which is the main reason why cataract patients find it difficult to see anything at night and need a lot of light when doing tasks. 

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Types of Cataracts According to Cause

There are many types of cataracts and they are classified according to what causes them and where which side of the lens is hardening. 

Age-related Cataracts

Age-related cataracts are due to normal changes in the eye as a person gets older. As the lens ages, the center of the lens or the nucleus hardens. This occurs in people over the age of 40. Age-related cataracts are the most common form of cataracts accounting for the majority of cataract cases. 

Pediatric Cataracts

Cataracts can also happen to children. Pediatric cataracts can have detrimental and permanent effects if they are left untreated. A child’s eye is still developing until they are 8 to 10 years old. Cataracts in children can be caused by metabolic diseases such as diabetes or eye injury. 

The types of cataracts that occur at birth or during the first year of a child are called congenital cataracts. Cataracts can happen to infants who had an infection such as HIV, rubella, chickenpox, syphilis, and herpes during infancy. This type of cataract may also occur in infants who were born prematurely or have a family history of congenital cataracts. 

Traumatic Cataracts

Cataracts can occur after a serious eye injury caused by blunt force or penetrating trauma to the eye. The cataract can occur right after the injury or years later. 

Secondary Cataracts

When a person undergoes cataract surgery, they are at risk of developing secondary cataracts. During eye surgery, the doctor replaces the hardened lens with an artificial one and is held in place in the eye’s natural lens capsule, the sac holding the lens. Some cells from the old lens remain inside the capsule. Weeks, months, or years later, the lens capsule starts to become cloudy. The condition is known as posterior capsular opacity, which is also dubbed as secondary cataracts. 

Polychromatic Cataracts

Characterized as needle-shaped opacities traversing through the lens, polychromatic or Christmas Tree cataract is a type of cataract often associated with myotonic dystrophy or progressive muscle deteriorating and weakness. This is a rare type of cataract that occurs in older people.

Diabetic Snowflake

White opacities that resemble snowflakes appear in the eye. This is a rare type of cataract that happens often to people who are diagnosed with diabetes preferably in young type 1 diabetics. 

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Types of Cataracts According to Site

Types of cataracts can also be classified according to which part of the lens is affected by hardening. 

Nuclear Cataracts

Most age-related cataracts are nuclear cataracts. Nuclear cataracts occur when the central part of the lens, known as the nucleus, starts to harden and gradually starts becoming yellow or brown. Untreated nuclear cataracts often result in difficulty distinguishing color. 

Cortical Cataracts

Streaks of white opacities that look like wedges start affecting the outer edges of the lens or the cortex. As cortical cataracts progress, the streaks start to extend to the center of the eye causing blurred vision, glare, and poor depth perception.

Posterior Subcapsular Cataracts

Small opacities occur at the back of the lens right at the path of light. This type of cataract is called subcapsular because it happens right beneath the sac that holds the lens in place (lens capsule).  Posterior subcapsular cataracts can cause reduced vision in bright light, difficulty reading, glare, and halos. This type of cataract has a faster progression compared to other types. 

Anterior Subcapsular Cataracts

Opacity occurs in front of the lens close to the lens capsule. This type of cataract usually occurs due to inflammation inside the other parts of the eye. 

Posterior Polar Cataracts

Hardening of the lens occurs in the central posterior or at the back part of the nucleus of the lens. This is often congenital and challenging to operate. 

Key Takeaways

There are different types of cataracts. Age-related cataracts are the most common form of cataract and often happens to old people. Cataracts can also occur in children. Other forms of cataract include those caused by diabetes, previous cataract surgery, and eye trauma. Cataracts are also classified according to which part of the lens is hardening. Cataracts may occur in the center, front, back, or side of the lens. 

Learn more about Cataracts here.