What is Cataract?
Our eyes have a lens which refracts the light rays that enter through the pupil. This lens should be clear to receive as much light as possible for optimum vision. However, in a cataract condition, the lens becomes cloudy causing blurred vision. Although the progression of cataract is often slow, it can lead to blindness in people over 40. Unfortunately, the condition is becoming increasingly more common, especially among older people.
What are the symptoms of cataract?
Cataract is painless, but it starts out as very minimal changes in vision. At first, a person with cataract will experience blurred vision, as if he/she is looking through a foggy glass window. Also, the patient may notice a halo-like glow around the headlights of cars or around lamp posts. Moreover,colors may seem more bland or faded;
they become less bright than they usually are. As cataract progress, vision deteriorates.
Symptoms of cataract vary according to which type of cataract the person has. There are some types which do not show any symptoms until the cataract is fully established.
How is cataract classified?
Senile (age-related) Cataract:
Age is the most common cause of cataract condition. Naturally lens proteins break down and degrade by time. However, there are some age-related diseases that accelerate this process, for example diabetes mellitus, hypertension and many others. Also, there are environmental factors that have cumulative
effect on the degeneration of proteins such as toxins, radiation, and ultraviolet light, since these factors lead to the loss of the protective and restorative mechanisms within the eye.
There are some factors that increase the risk of cataracts including:
- Prolonged use of corticosteroid medications
- Previous eye injury or inflammation
- Previous eye surgery
- High blood pressure
Senile cataract can be classified into 3 types according to the location and propagation of the condition:
The first and the most common type is the nuclear cataract which starts in the central zone of the affected lens. This type is usually related to aging. When this type first develops, it can cause what is called “second sight” which is a phenomenon characterized by temporary improvement in near vision. However, as the cataract worsens, this effect disappears and vision deteriorates.
The second type is the subcapsular cataract which develops at the back of the lens. Diabetic patients and people taking steroid drugs in high doses have higher risk of developing this type of cataract. This type is a silent one meaning that no symptoms appear before the cataract is well established.
The third type is the cortical cataract that affects the cortex or outer coating of the lens. It is characterized by white opacities starting from the peripheral edges of the lens and spreading to the center.
Cataract can result from both mild and severe blunt trauma to the eye. With mild blunt trauma, swelling and whitening of the lens often result. Although the swelling may resolve by time, the white color persists. On the other hand, severe trauma to the eye can involve a breach and damage of the eye capsule that contains the lens.
This in turn causes the fluid from the other parts of the eye to enter the capsule which then swells and whitens. Unlike in mild blunt trauma, both the swelling and whitening persist and block the light from reaching the retina at the back of the eye. Cataract resulting from mild blunt trauma differs in shape from the ones resulting from severe trauma.
There are several kinds of radiation that cause cataract such as ultraviolet light coming from the sun, microwave radiation, ionizing radiations like X-rays, electrical and heat energy and finally Laser. The mechanism of how these radiations cause cataracts is not yet clear. However, there are some suggested mechanisms. For instance, heat-sensitive enzymes exhibit changes that hinder their protective function within the eyes. Also, the lens can be directly damaged by the pressure waves generated in the eye fluid. Moreover, heat and electric injuries cause lens proteins to coagulate
and whiten in the same way cooking coagulates the protein parts of an egg. Despite the differing mechanisms, all these radiations damage the lens and cause cataract formation. So people who work in any field that requires the use of radiation should have regular checkups to make sure a cataract is not developing.
In addition, there are some diseases like diabetes and some inherited disorders that can cause cataract. Also, some medications such as inhaled corticosteroids as well as smoking increase the chances of cataract formation.
How is cataract treated?
Cataract is treated surgically. Cataract extraction surgery involves the removal of the natural lens that became opaque as a result of the development of a cataract condition. Next, a man-made lens called an intraocular lens (IOL) replaces the removed cataract lens to rebuild focusing power of the lens and to help improve vision.
Cataract surgery is successful and quite safe, as very few patients develop complications. The duration of surgery is usually not more than half an hour to an hour. It is an outpatient procedure meaning that the patient can go home on the same day of the surgery.
For adults, local anesthesia is usually all that is required for the procedure. Medications to relax the patient are also given. Since children are hard to handle during surgery, they usually receive general anesthesia to make them unconscious.
How is cataract extraction surgery performed?
Generally, the ophthalmologist views the eye using a microscope and then makes a small incision in the outer coating of the eye, the cornea. The ophthalmologist then decides on the technique by which the lens is removed according to the condition of the patient.
This method of cataract extraction involves the use of sound waves to disintegrate cataract into small pieces. The pieces are then suctioned out. The advantage of this method is that it requires a very small incision.
Here, a small tool is used to remove the cataract as a whole. This involves a larger incision compared with other methods of extraction.
Performing this kind of cataract extraction involves the use of laser energy to make the incisions and soften the cataract. Then the cataract is extracted in a way that is similar to phacoemulsification. The use of laser will accelerate recovery and improve accuracy.
When is surgery needed?
Cataracts are painless and do not always affect vision. However, in some cases the lens becomes so unclear and cloudy that light is blocked, and the patient’s vision is compromised. You should discuss with your doctor the optimal timing to have the procedure performed.
If you or one of your family members have any of the cataract risk factors or started complaining of blurry vision associated with faded colors and/or appearance of halo-like glow around the headlights of cars or around lamp posts, you should check with an ophthalmologist. Contact us and book your appointment with Dr. Ramy Riad.