You can read about Cataract below, or click on the following link to watch a video about cataract, cataract surgery, lens implants and after-cataract laser treatment.
The lens is located immediately behind the iris.
Like the lens in a camera it focuses light onto the retina.
In a young person the lens is clear like glass, with no significant opacity or color tint. As time goes by, in everyone’s life, the lens undergoes a change in clarity and color, becoming increasingly hazy and changing color from a yellow-green tint (see photo below) that progresses to orange and brown.
Slit lamp view of the lens through a dilated pupil.
The slip beam, coming at an angle from the left, first cuts through the cornea (broken arrows), followed by a dark gap for the anterior chamber, then it lights up a large section through the lens (solid arrows). This lens is average clarity for a person of 50 years of age.
When the lens becomes cloudy we call it a cataract.
Some things that are associated with accelerated cataract development are extended UV exposure, Diabetes, trauma and Prednisone use.
Objectively we measure a cataract by how much it reduces visual acuity. For example a mild cataract might reduce vision to 20/25 to 20/30, a moderate cataract to 20/40 to 20/60.
Decision About Cataract Surgery
Rule #2. Everyone gets some degree of cataract with time, but just because you have a cataract does not mean you need to have surgery.
As the lens gets cloudier you may notice increased glare along with reduced vision. Sometimes the combination of blur and glare results in more impairment in function than is necessarily measured in the specialized circumstances of the exam lane. When reduced vision interferes with things that are important to you, like driving, reading or job performance, then it is time to consider cataract surgery.
Modern cataract surgery is a technologic marvel. The cloudy natural lens is removed and replaced with a new artificial lens. Done under local anesthetic, the procedure usually takes under half an hour and you are back to your normal activities in a few days. Newer intraocular lens designs are promising less dependence on glasses.
Rule #3. It is important to remember that while the complication rate of cataract surgery is low, it is not zero, and the new lenses have their downsides. Consider your decision for surgery and lens choice carefully.
This photo shows an extreme example of clouding of the lens, reducing vision to the ability to see only light and dark.
At cataract surgery the main cloudy part of the lens is removed leaving the back part of the lens (the capsule) in place to support the lens implant (IOL). Picture the lens as an avocado. Surgery involves removing the pit and the meat, leaving the skin in place. The IOL is inserted into the remaining capsule like a sandwich in a sandwich bag.
The steps in cataract surgery:
- The eye is anesthetized with drops on the surface.
- A small incision, 1/4 of an inch, is made though the edge of the cornea.
- The front capsule of the lens is opened.
- A phaco instrument, its tip vibrating at ultrasonic frequency, is used to break up the lens into small fragments that are vacuumed out of the eye.
- The main part of the lens capsule is intentionally left in place.
- The lens implant is folded up and inserted through the corneal incision into eye, where it unfolds within the lens capsule.
- The surgeon verifies the lens is well positioned.
- The eye is reinflated with saline to normal pressure which causes the corneal incision to seal like a trap door.
Through the dilated pupil a lens implant (IOL) is visible. It is tricky to see because it is clear. The solid arrows point to the edge of the circular optic of the IOL. The end of one of the stabilizing arms can be seen embedded in the clear optic at about 6 o’clock position.
The diagram below shows an IOL oriented at the same angle as the lens in the photo.
At surgery an opening is made in the front of the capsule so the cloudy lens material (cataract) can be removed. The IOL is inserted into the capsule with the arms (haptics) keeping the lens positioned in the center. Within weeks the capsule contracts around the IOL holding it securely in position.
Diagram, side view of the IOL within the lens capsule.
Months to years after surgery, the capsule may become cloudy and interfere with vision much like the original cataract. My mental picture is of a sheet of wax paper behind the lens.
The white ring shown by the broken arrow is the part of the capsule in front of the IOL. The IOL is clear. The hazy area indicated by the solid arrow is clouding of the posterior capsule behind the lens. See the diagram above.
Using a YAG laser an opening can be made in the clouded back capsule to restore vision to the postop level of clarity.
Capsule Opened with Laser
The picture shows a clouded capsule opened with a YAG laser. Compare with the previous picture where there was a cloudy area behind the lens, now there is a clear opening.