Intraocular Lens
Introduction
Before the development of intraocular lenses (IOLs), people had to wear very thick eyeglasses or special contact lenses to be able to see after cataract surgery. Several types of IOL implants are available to help the people to enjoy improved vision. These options should be discussed with the eye specialist to determine which IOL best suits the patient’s vision needs and lifestyle.
Cataract lens replacement: Function of IOLs
Similar to the natural lens of the eye, an IOL focuses light coming into the eye through the cornea and pupil onto the retina, the sensitive tissue at the back of the eye which relays the images through the optic nerve to the brain. Most IOLs are made up of a flexible, foldable material and they are about one-third of the size of a dime. Like the lenses of prescription eyeglasses, the IOL also contains the appropriate prescription mentioning its power or ability of focusing to give the best vision possible.
Iran is now ranking first both in the region and in the Middle East and the Iranian ophthalmology science is among the world top majors
Which lens option is right for you?
Before cataract surgery, the eyes are measured to determine the required power of IOL. The patient and specialist should compare the options available to decide which IOL type is best for a specific cause.
The type of IOL implanted affects the vision while the patient is not wearing eyeglasses. Glasses may still be needed by some people for some activities.
In certain cases, the choice of IOLs depends upon the cost as selecting special premium lOLscan reduce the need for glasses.
Intraocular lens (IOL) types
1. Monofocal lens:
This is a common IOL type being used for several decades. Monofocals are designed to provide best corrected vision for near, intermediate or far distances.
Most people who choose monofocals have their IOLs set for distance vision and use reading glasses for near activities. On the other hand, if the IOLs are set to correct near vision, the patient will need glasses to see distant objects clearly.
2. Monovision:
Some patients who choose monofocals decide to have the IOL for one eye set for distance vision, and the other set for near vision. This is a strategy called as monovision. The brain adapts to the different information from both the eyes to provide vision at intermediate distances. This can reduce the need for reading glasses. This lens is useful especially for people regularly using computers or other digital devices. Individuals considering monovision are advised to try this technique with contact lenses first to adjust to monovision. These lenses are not for people requiring crisp, detailed vision.
3. Multifocal or accommodative lenses:
These newer IOL types reduce or eliminate the need for glasses or contact lenses. In this type, a series of focal zones or rings is designed into the IOL. Depending on where incoming light focuses through the zones, the person may be able to see both near and distant objects clearly.
The design of the accommodative lens allows certain eye muscles to move the IOL forward and backward. This causes change in the focus as with a natural lens, allowing near and distance vision.
IOLs include filters to protect the eye’s retina from exposure to UV and other potentially damaging light radiation.
The ability to read is generally best when multifocal or accommodative IOLs are placed in both eyes.It usually takes 6 to 12 weeks for the brain to adapt to these lenses after surgery on the second eye.
The visual success with these IOLs also depends on the size of the pupils and other eye health factors.
Side effects can occur such as glare or halos around lights, and decreased sharpness of vision (contrast sensitivity), especially at night or in dim light. Most people adapt to these effects, but those who frequently drive at night or need to focus on close-up work usually benefit more from monofocal IOLs.
4. Toric IOL for astigmatism:
This is a monofocal IOL with astigmatism correction built into the lens. Astigmatism is an eye condition which distorts or blurs the ability to see both near and distant objects. In astigmatism, the cornea (the clear front window of the eye) is not round and smooth, but instead it is curved. People with significant degrees of astigmatism require toric IOLs.
Other cataract lens replacement considerations
IOLs include filters to protect the eye’s retina from exposure to UV and other potentially damaging light radiation. These filters are selected by the eye specialist to provide appropriate protection for the patient’s specific needs.
Sometimes, after healing completely from the cataract lens surgery, some patients may need further correction to achieve still better vision. Additional surgery may be advised to exchange an IOL for another type or implant an additional IOL.
People who have had refractive surgery such as LASIK need to be carefully evaluated before getting IOLs as the power of the IOL required may be affected by the previous refractive surgery.