A cataract is a clouding of the eye’s natural lens, the clear structure behind the colored iris. The lens focuses light onto the retina to produce sharp images. When a cataract forms, proteins and fibers within the lens break down and clump together, making the lens opaque. This obstructs the path of light, resulting in vision that is like looking through a foggy or frosted window.
Common Symptoms of Cataracts
The visual changes from a cataract often develop gradually, and initial symptoms may be subtle. A primary indicator is increasingly blurry or cloudy vision, which can make activities like reading or recognizing faces more difficult. Many people also experience heightened sensitivity to light and glare, noticing that sunlight or oncoming headlights seem unusually bright and distracting. This can lead to seeing “halos” or streaks around light sources, particularly at night, which can impact driving.
Another common symptom is a change in color perception; colors may appear faded, washed out, or tinged with a yellowish-brown hue. This occurs as the clouded lens filters and distorts the light entering the eye. Some individuals find they need brighter light for reading and other close-up tasks. It is also common for a person’s eyeglass or contact lens prescription to change more frequently as the cataract progresses.
The specific symptoms can also vary depending on where the cataract forms on the lens. The three most common types are nuclear, cortical, and posterior subcapsular cataracts. For example, a nuclear cataract, which forms in the center of the lens, may temporarily improve near vision, a phenomenon sometimes called “second sight.” A posterior subcapsular cataract, located at the back of the lens, often causes significant glare and affects reading vision.
Factors Contributing to Cataract Development
Aging is the most prevalent cause of cataracts. After about age 40, the proteins that make up the eye’s lens naturally start to change and break down, leading to the cloudiness that characterizes a cataract. While most people over 60 have some degree of lens clouding, significant vision problems might not develop until years later.
Beyond the natural aging process, several other factors can accelerate cataract formation:
- Prolonged and unprotected exposure to the sun’s ultraviolet (UV) radiation, which damages the proteins in the lens over time.
- Certain medical conditions, most notably diabetes. High blood sugar levels can cause the lens to swell and alter its protein structure.
- Smoking, as studies have shown it doubles the risk of developing cataracts compared to non-smokers.
- Excessive consumption of alcohol, which can also increase risk.
- The long-term use of steroid medications, whether taken orally, through an inhaler, or as eye drops.
- Previous eye injuries or surgeries, which can lead to what is known as a traumatic cataract.
Medical Diagnosis and Management
An eye care professional diagnoses a cataract through a comprehensive eye examination. The process begins with a visual acuity test, which uses an eye chart to measure how well a person can see at various distances. The most definitive part of the diagnosis involves a slit-lamp examination. This specialized microscope allows the doctor to see the cornea, iris, and lens in fine detail and identify the location and density of any cloudiness.
To rule out other causes of vision loss, the doctor will also perform a retinal exam. This requires dilating the pupils with eye drops to get a clear view of the structures at the back of the eye, including the retina and optic nerve. This step ensures that no other conditions, such as macular degeneration or glaucoma, are contributing to the patient’s symptoms.
In the early stages of a cataract, when symptoms are mild, surgery may not be immediately necessary. Vision can often be managed with non-surgical methods, such as updating eyeglass or contact lens prescriptions. Using brighter lighting for reading and other tasks can also make a significant difference, and anti-glare sunglasses can provide relief.
The Surgical Solution for Cataracts
When a cataract progresses to the point where it interferes with daily activities like driving or reading, surgery is the effective treatment to restore clear vision. The procedure is recommended when updated glasses and other management strategies no longer provide adequate visual function. Cataract surgery is one of the most common and successful surgical procedures performed worldwide.
The standard technique is called phacoemulsification. During this procedure, the surgeon makes a very small incision on the edge of the cornea. A tiny probe is inserted through this opening, which emits high-frequency ultrasound waves to gently break the cloudy lens into small fragments. These pieces are then carefully suctioned out of the eye.
Once the clouded natural lens is removed, a clear, artificial lens called an intraocular lens (IOL) is implanted in its place. The IOL is folded to fit through the small incision and then unfolds into position inside the lens capsule. The IOL becomes a permanent part of the eye, requires no care, and is not felt by the patient.
There are several types of IOLs available to meet different visual needs. Monofocal IOLs are the most common and are set to provide clear vision at a single distance, so patients will still need glasses for reading. Multifocal and trifocal IOLs have different zones set at different powers, allowing a person to see clearly at multiple distances. For individuals with astigmatism, toric IOLs can correct this issue at the same time the cataract is removed.