If you live long enough, you will likely develop cataracts. It is the leading cause of treatable blindness. Predictions are that there are over 30 million people suffering from cataracts already in the United States and that number is expected to rise. Only about 10% of those people undergo cataract surgery yearly with a success rate of 95% with the best corrected vision. Globally, cataract is also a leading cause of visual impairment and blindness with incidences higher than 80% in countries such as India. It is estimated that 1.2% of the entire African population is blind. Early detection and surgical intervention is the goal of improving vision worldwide.
Cataracts are the most common and treatable cause of vision loss and blindness.
Cataracts arise from a combination of environmental, nutritional, and systemic reasons.
The only proven treatment for cataracts is surgery which involves lens replacement.
What is senile cataract?
A cataract is a natural clouding of the lens inside the eye, called the crystalline lens. Changes in clarity occur that slowly diminish visual quality. The lens plays a vital role in focusing unimpeded light on the retina for accurate relaying of visual information to the brain.
The term “cataract” is from the Greek word “cataractos” which means rapidly running water. The concept used by the Greeks to describe cataracts refers the water that becomes turbulent can be transformed from clear to white and cloudy.
Early in life, the crystalline lens is clear and light passes through it flawlessly. With time, the lens becomes cloudy and causes blurry, hazy, and/or less colorful vision. Cataracts are called senile or age-related because cataracts develop as a gradual process of normal aging, but there are exceptions when they can occur more rapidly. Most cataracts affect both eyes.
There are various types of cataracts. All cataracts fundamentally change the clarity of the lens structure. The three most common medical descriptions of cataracts include nuclear sclerosis, cortical, and posterior subcapsular cataract (PSC). These cataracts are not mutually exclusive, meaning people frequently develop some combination of the three.
what are the 3 types of cataracts?
There is still much to learn about the origin and pathology behind cataracts. It is probable that cataracts arise from complex, multifactorial physiological processes with a mix of environmental, nutritional, and systemic reasons.
The most common type of cataract is nuclear sclerosis which means the central portion of the lens is most affected. Nuclear cataracts result in yellowing of the lens with a resulting central opacity. Sometimes nuclear cataracts become brown and are called a brunescent nuclear cataract.
Nuclear sclerosis causes blurred vision, which typically bothers patients more at distance than it does at near. This type of cataract can cause changes in a patient’s glasses prescription, often resulting in myopia (or nearsightedness). While this makes distance vision more difficult, it may also make it easier to see things up close. Night driving might become a problem, as could seeing in a dark setting such as a movie theater. This is because cataracts reduce the amount of light getting to the eye. Glare may also become an issue, as could decreased contrast and color discrimination. Some people will experience a shadow behind objects, which could appear as double vision.
Cortical cataracts mean that there has been a change in the ionic composition of the surface of the lens or cortex. Eventually when there is a change in the hydration of the lens fibers a cortical cataract is formed.
Cortical cataracts also cause blurry vision, though they often have an equivalent effect on both far and nearsightedness. Glare and contrast sensitivity may also become issues.
PSC (Posterior Subcapsular Cortex)
While nuclear sclerosis and cortical cataracts tend to progress rather slowly, PSCs evolve more rapidly. PSCs occur as a result of granular and plaque like opacities in the back surface of the eye lens, hence posterior, beneath the lens capsule that holds the lens in place. Most patients notice glare and decreased visual acuity especially during bright sunlight, but can see well if the lights are dimmed. PSCs can occur from aging or as a complication of other conditions such as inflammation, surgery or trauma. There may be more blur close up than there is at distance, though this varies. Glare may also be a problem.
While the three types of cataracts may cause slightly different symptoms, many of these signs tend to overlap. Every patient experiences cataracts differently, depending on their visual needs. Many people also have more than one type of cataract develop, which contributes to the variability in symptoms.
Age is the primary risk factor for getting cataracts. Other reasons why cataracts might develop include:
- Family history. If your siblings, parents, or other family members have cataracts, you may be more prone to developing them.
- Medical conditions. Diabetes, for example, increases a person’s risk of cataracts. Patients with diabetes may be up to five times more likely to develop cataracts at an early age.
- Smoking. Smoking increases the risk of cataracts, possibly due to the oxidative stress it causes to the body.
- Trauma. Having an eye injury or eye surgery could precipitate the development of cataract. Furthermore, radiation treatment to the head or neck could also have an impact.
- Ultraviolet (UV) exposure. Spending a lot of time in the sun without adequate eye protection may accelerate the development of cataracts. Wearing sunglasses can help to prevent this.
- Medications. The use of corticosteroid medication can precipitate early cataract formation.
The refractive changes that accompany cataract formation can sometimes be managed with a change in glasses. However, this will only improve vision temporarily. In other words, it won’t treat the underlying cause of the change in vision. Using increased illumination may also help manage the decreased light getting to the eyes.
Ultimately, the best treatment for cataracts is surgical intervention. Your doctor will recommend surgery once cataracts begin keeping you from doing the things you want to.
The standard surgery for cataracts is performed in a hospital or ambulatory surgery center as an outpatient. The surgery process is called phacoemulsification. The doctor makes a very small incision in the surface of the eye in or near the cornea. A tiny ultrasound probe is inserted into the eye and using ultrasound the natural lens is dissolved or phacoemulsified and removed. Once the lens is removed, the doctor will replace it with artificial lens.
Rarely, a person’s vision declines following cataract surgery. This could occur months or years after the initial procedure and may be due to a clouding of the lens capsule, called posterior capsule opacification (PCO). PCO is sometimes referred to as a secondary cataract and can be treated with a laser procedure.
Cataracts are caused by a gradual clouding of the natural lenses in our eyes. Certain factors may accelerate their development, such as family history, diabetes, smoking, sun exposure, trauma, and steroid use. While the vision changes associated with cataracts may be temporarily managed with a change in glasses or more light, the most effective and ultimate treatment is surgery. Cataract surgery involves the removal of the cloudy part of the lens and replacement with an artificial lens that is highly successful in improving vision with few side effects or complications.
- Boyd, K. Cataract Surgery: Risks, Recovery, Costs.
- Javitt JC, Wang F, West SK. Blindness due to cataract: epidemiology and prevention.
- Kiziltoprak H, Tekin K, Inanc M, Goker YS. Cataract in diabetes mellitus.
- Nei.nih.gov. Cataract Data and Statistics.
- Nei.nih.gov. Types of Cataract.
Show all references
- Ye J, He J, Wang C, et al. Smoking and risk of age-related cataract: a meta-analysis.