A complete guide to the different types of cataracts
Cataracts are not a rare or new eye condition. In fact, The World Health Organization regards cataracts as the leading cause of blindness worldwide, accounting for 51% of all blindness around the globe.
While the prevalence of cataracts gives many adults a sense of familiarity with the condition, their knowledge typically ends there: That cataracts are an eye condition that impacts vision. However, cataracts vary in many ways, including where they are located in the lens, how they look and who they affect.
This brief guide to different types of cataracts explains these differences, as well as what can cause them and other risk factors.
Types of cataracts
Types of cataracts are categorized by what kind of change is happening to the lens (color, structure, etc.) and where in the lens they are located. Cataracts can develop at the back (posterior) of the lens, the center (nucleus) of the lens or around its periphery.
Cataract types: The basics
Incipient cataracts are new, immature cataracts. The lens is only slightly clouded, and the portion of the lens surrounding the nucleus is typically clear.
Intumescent cataracts are mature cataracts that are usually accompanied by opaque, swollen lenses due to the deterioration of lens proteins. These can lead to narrow-angle glaucoma.
Bilateral cataracts simply means cataracts are present in both eyes. This term applies to any type of cataract.
Early onset cataracts refers to cataracts that develop before the age of 40 due to poorly controlled medical conditions, medications, trauma or heredity.
Secondary cataracts, also called after-cataracts or posterior capsular opacification (PCO), are not actually true cataracts. PCO is a condition that sometimes occurs after cataract surgery. It is a clouding of a thin, clear membrane (the posterior lens capsule) that’s left inside the eye when a cataract is removed. It’s located directly behind the artificial intraocular lens that’s implanted in the eye to replace the natural lens. If this membrane becomes cloudy, it can mimic the visual effect of a cataract. PCO can be treated with an in-office laser procedure.
Age-related cataracts
Nuclear cataracts, also called nuclear sclerosis or nuclear senile cataracts, form in the center (nucleus) of the lens, causing the nucleus to become yellow or even brown, and eventually opaque. Nuclear cataracts usually develop slowly and commonly occur in both eyes. According to the American Academy of Ophthalmology (AAO), they tend to affect distance vision to a greater degree than near vision. Other symptoms of nuclear cataracts include a fading of colors (especially blue objects) and a shift toward increased nearsightedness, AAO says.
Cortical cataracts are characterized by wedge-shaped opacities (often called cortical spokes) that form in the lens cortex, which is the part of the lens that surrounds the central nucleus. These spoke-like opacities usually begin near the periphery of the lens, where they cause no vision problems. But as cortical cataracts worsen and start to grow toward the central portion of the lens — either in front of the nucleus (anterior cortical cataracts) or behind it (posterior cortical cataracts), they cause blurred vision and significant glare from car headlights and other bright lights.
Congenital cataracts
Congenital cataracts are present at birth. They can be small and have little effect on vision, or they can be dense and require cataract surgery. If significant, congenital cataracts increase a child’s risk for developing amblyopia, also known as lazy eye.
Genetic factors and underlying diseases can play a role in causing congenital cataracts, but the reasons they occur are often unknown.
Cerulean cataracts are a type of congenital cataract that presents a bluish-white hue within the lens. These usually occur in both eyes and worsen over time. Cerulean cataracts may be present at birth or develop in very early childhood, but they might not be diagnosed until adulthood, according to the National Institutes of Health’s Genetic and Rare Diseases Information Center.
Polar cataracts are usually small congenital opacities located in the central part of the lens. These can be in the front (anterior polar cataracts) or back (posterior polar cataracts) of the lens and often appear as a little dot in the middle of a child’s pupil. Anterior polar cataracts usually remain small and do not significantly affect vision. Posterior polar cataracts may worsen and require surgery. However, polar cataracts can cause unequal refractive errors in the two eyes that can put a child at risk of amblyopia.
SEE RELATED: Pediatric cataracts
Other cataract types
Rosette cataracts are trauma-induced cataracts that can be seen in the anterior or posterior region of the lens. The lens opacities form what look like petals and take on a flower-like appearance.
Subcapsular cataracts are cataracts located below the lens capsule. They can be located in the front (anterior) or back (posterior) portion of the capsule that surrounds the lens.
Posterior subcapsular cataracts (PSC) occur at the very back of the lens, just inside the posterior lens capsule. Because they often occur in the central zone of the lens, PSCs can cause significant vision problems and require surgical treatment. Long-term use of oral corticosteroid medications has been identified as a risk factor for posterior subcapsular cataracts.
Anterior subcapsular cataracts are the same as PSC but are located in the front center of the lens. They are less common than PSCs and it appears the greatest risk factor is trauma to the eye.
Christmas tree cataracts are a rare, age-related cataract resembling colorful Christmas tree needles that is associated with myotonic dystrophy.
Snowflake cataracts are a rare type of cataract often associated with diabetes. It can develop in patients with uncontrolled Type 1 diabetes. A snowflake cataract looks like white specks that resemble snowflakes.
SEE RELATED: At what stage should cataracts be removed?
Causes of cataracts
Cataracts are a change to the lens of the eye that appears as a cloudy film. The lens, located behind the iris (the colored part of the eye), is made up of proteins called crystallins and plays a primary role in the clarity of vision.
When these proteins begin to clump together, either due to age, injury, or other cataract causes, they begin to form a milky haze over the eye that is commonly associated with the condition.
Aging: As you age, proteins in the eye’s lens naturally begin to break down and clump together, making aging the most common cause of cataracts.
Smoking: It is believed that smoking alters lens cells through oxidation, which leads to cataract development.
Certain medical treatments: Medications such as oral steroids or radiation treatment for cancer can promote the development of cataracts.
Underlying conditions: High blood pressure and diabetes may accelerate cataract development.
Trauma: Chemical, blunt or penetrating trauma to the lens can irritate lens fibers and result in cataract development. This can happen at any age.
UV exposure: Prolonged, unprotected UV exposure can damage the lens, cornea and surface tissues of the eye. The same sun exposure that leads to skin cancer can lead to cataracts.
Certain childhood syndromes: Congenital cataracts are most often found in children with Down syndrome, Chondrodysplasia syndrome and Lowe syndrome, among many others.
Risk factors for cataracts
Mature age (over 40)
Smoking
Accumulated sun exposure
Obesity
High blood pressure
Diabetes
Past eye injury
Family history of cataracts
Prolonged steroid use
Radiation exposure
Excessive alcohol consumption
While most cataracts develop rather slowly, they will ultimately hinder your ability to see. The job of the lens is to help focus images onto the light-sensitive retina at the back of the eye. As cataracts progress, they block the amount of light that reaches the retina, resulting in blurry vision and possibly even legal blindness.
Cataract surgery is currently the only scientifically proven way to eliminate cataracts. However, there are some ways to treat the symptoms of the earlier stages of cataracts, as well as some natural remedies that may be helpful for some cataract patients.
READ MORE: Cataracts, marijuana and CBD
Page published on Thursday, August 20, 2020
