WHAT IS A CATARACT ?
A cataract is a loss of transparency, or clouding, of the normally clear lens of the eye. This lens is a part of the eye that helps focus light on the retina. It is located behind the iris. The term cataract is derived from the Greek word cataractos, which describes rapidly running water. When water is turbulent, it is transformed from a clear medium to white and cloudy. Cataract development is usually a very gradual process of normal aging but can occasionally occur rapidly.
Many people are in fact unaware that they have cataract because the changes in their vision have been so gradual. Cataract commonly affect both eyes, but it is not uncommon for cataract in one eye to advance more rapidly. Some children develop cataract, called congenital cataract, before or just after birth; these are usually dealt with differently from cataract in adults.
WHAT CAUSES CATARACT ?
The lens of the eye is located immediately behind the iris and is responsible for 33% of the eyes focusing power. At birth it is like jelly, but unfortunately with age it gradually hardens and loses its ability to change shape.
Evidence of this hardening normally starts to affect us in our mid-forties when many require reading glasses for close work. This is called Presbyopia. The lens is made mostly of water and protein. Specific proteins within the lens are responsible for maintaining its clarity. Over many years, the structures of these lens proteins are altered, ultimately leading to a gradual clouding of the lens. Rarely, cataract can present at birth or in early childhood as a result of hereditary enzyme defects, and severe trauma to the eye, eye surgery, or intraocular inflammation can also cause cataract to occur earlier in life. With further increase in age, the lens continues to harden and starts to become more compact and cloudy, reducing initially quality of vision and later obstructing vision and interfering with day to day activities. A cloudy of opaque lens is called a cataract and unfortunately is inevitable.
WHAT ARE CATARACT SYMPTOMS ?
The typical symptom of cataract formation is a slow, progressive and painless decrease in vision of variable degrees. The loss of transparency of the lens may be so mild that vision is hardly affected, or so severe that no shapes or movements are seen. Common symptoms of cataract include.
A painless blurring of vision, Glare, or light sensitivity, Frequent eyeglass, Prescription changes, Double vision in one eye, Needing brighter light to read, Poor night vision & Fading or yellowing of colors.
When to Seek Medical Care- Eye-care professionals may mention during a routine eye exam that you have early cataract development even if you are not yet experiencing visual symptoms. Although your doctor will be able to tell when you first begin to develop cataract, you will generally be the first person to notice changes in your vision that may require cataract surgery. Clouding of the lens may start to be seen at any age, but it is uncommon before the age of 40.
However, a large majority of people will not begin to have symptoms from their cataract until many years after they begin to develop. Since cataract development rarely causes any long-term damage to the eye, cataract surgery should be considered only when visual symptoms begin to develop. Whenever significant vision problems are noted, you should schedule an exam by an eye-care professional.
Typical symptoms may include blurry vision, difficulty with glare or night vision, poor color vision, or frequent changes in eyeglass prescription. For an early cataract changes, vision may be improved by simply changing your eyeglass prescription, using a magnifying lens, or increasing lighting when you do visually demanding tasks.
Eventually, cataract get to a point where the only effective intervention is surgery. This decision is made based mainly on the degree of visual limitation the patient is experiencing.
THE RISK FACTORS INCLUDE :
Age: Most people older than 60 years have cataract.
Medical conditions: Diabetes and other systemic diseases, glaucoma, and metabolic abnormalities can cause cataract. We can work to control these causes.
Eye injuries: These are called traumatic cataract. A blow to the eye, great heat or cold, chemical injury, exposure to radiation and other injuries can lead to cataract formation. We can limit this with immediate treatment.
Ultraviolet radiation (UVA or UVB): Long-term exposure to sunlight is believed to speed the development of cataract. We can help prevent this with proper protection in your glasses.
Smoking: All studies indicate that smokers are twice as likely to develop cataract as nonsmokers and that quitting can reduce the risk for developing cataract. We will try to help you with this.
EXAMS AND TESTS :
To detect a cataract, the eye-care provider examines your lens. A comprehensive eye examination usually includes the following:
Visual acuity test : An eye chart test is used to measure your reading and distance vision.
Refraction : Your eye doctor should determine if glasses would improve your vision.
Glare testing : Vision may be significantly altered in certain lighting conditions and normal in others; in these circumstances, your doctor may check your glare symptoms with a variety of different potential lighting sources.
Potential acuity testing : This helps the ophthalmologist get an idea of what your vision would be like after removal of the cataract. Think of this as the eye's vision potential if the cataract was not present.
Contrast sensitivity testing : This check for your ability to differentiate different shades of gray, which is often this limited by cataract.
Tonometer : a standard test to measure fluid pressure inside the eye (Increased pressure may be a sign of glaucoma.)
Pupil dilation: The pupil is enlarged with eye drops so that the ophthalmologist can further examine the lens and retina. This is important to determine if there are other conditions which may ultimately limit your vision besides cataract.
IOL Master: A new dimension in optical biometry to improve postoperative refractive results. It is a gold standard in biometry (calculating IOL power)
Today, cataract treatment involves a lot more than the replacement of the crystalline lens. Refractive improvement is often also required. Premium IOL are now being increasingly used to meet patient demands. Hence accurate IOL power calculation is an absolute must. The IOL Master provides you with highly precise measuring data as a basis for optimum vision for patient.
The IOL Master can also be used to precisely and reliably measure problematic cases such as staphyloma, highly myopic, or silicone-filled eyes.
The Haigis-L formula offers a convenient solution for eyes subsequent to refractive surgery performed for the correction of myopia and hyperopia. The calculation of phakic implants is also possible.