Intraocular Lens

By Prithvi Basak

Definition: Cataract results in blurred vision and results in blindness. An intraocular lens (IOLs) can rectify the complications of cataracts and presbyopia. The doctor conducts surgery to implant IOLs in the patient's eye by replacing its natural lens.

The aging process causes the covering of the cornea or the eye's natural lens by a cloudy layer. It hinders light entry into the eye lens, and the eye fails to form an image in the retina. Thus, it results in the loss of vision. However, the intraocular lens can solve the problems due to cataracts. IOLs are a small and lightweight clear plastic that improves the focusing power of the eye. It helps the formation of an image in the retina and thereby, made the vision possible.

The material of IOLs may be hard plastic, soft plastic, or soft silicone. Unlike the contact lenses, the patient does not need to replace the intraocular lens. It does not need to remove, clean, and reinsert the intraocular lens. Instead, doctors place the intraocular lens before or behind the iris and, the latter is the better option. Ophthalmologists incise the cornea and remove the natural lens and then replace it with a suitable intraocular lens.

Types of Intraocular Lens

Clear plastic is the material used to make intraocular lenses. There are a variety of intraocular lenses based on the lifestyle and the problems of the eye. Some of the types of intraocular lenses and their peculiarities include;

• Aspheric intraocular lens: It is different from the traditional intraocular lens in its manufacturing procedure and design. Aspherical intraocular lenses resemble the exact shape of the eye's natural lens and help in low-light vision.

• Toric intraocular lens is an efficient medical device that provides sharp vision like the eye's natural lens. Doctors recommend the Toric intraocular lens implant surgery to rectify astigmatism. The toric intraocular lenses exhibit different powers in various medians on the lens. The alignment markings in its peripheral part help the surgeon place the toric intraocular lens in its correct place. Surgeons create temporary markings on the cornea of the patient's eye. It guides the surgeon to locate the most curved meridian of the eye. The temporary markings on the cornea help the surgeon set a proper alignment of the toric intraocular lens while rotating it. The surgeon conducts Limbal Relaxation Incisions (LRI) before toric intraocular implant surgery to rectify astigmatism. Small incisions on the cornea help to attain a spherical shape and thereby reduces the occurrence of astigmatism.

• Accommodating intraocular lens: It is an artificial lens that is different from the standard intraocular lens. Unlike the standard intraocular lens, accommodating IOLs can change the focus according to the distance of the objects. It helps the patients to reduce the use of glasses while reading and driving. The flexible arm called haptics in the accommodating intraocular lens can work according to the movements of muscles in the eye. The contraction of the ciliary muscles results in the bending of flexible haptics. It causes the focus area to move forward and helps in accommodation.

• Multifocal lens: It helps to rectify presbyopia and reduces the requirement of glasses while reading and driving after the surgery. The multifocal lens consists of added magnification in various regions of the lens. It helps in the expansion of the range of vision and ensures clear vision at all distances. A multifocal lens can provide better near vision comparing the accommodating intraocular lens. However, multifocal lenses may result in mildly blurred vision.

Procedures of Intraocular Lens Implantation Surgery

An ophthalmologist is the eye specialist who recommends the patients conduct surgery to remove the dangerous cataract from their eye. They implant the intraocular lens with clear vision. The total duration for the surgery in one eye is 15 to 30 minutes. Some of the procedures of intraocular lens implantation surgery include;

• Measuring the eye by ophthalmologists is the primary step of the surgery. It helps the professionals to decide the suitable intraocular lens implants for the patient's eye.

• The doctor advises the patients not to wear contact lenses before surgery for several days.

• Doctors provide eyedrops several days before the surgery to prepare the patient for their surgery.

• Doctors provide valium for relaxing the patients and then anesthesia to numb the eye.

• Sometimes doctors provide painless injections around or behind the eye to reduce the movement of the eye.

• Professionals place a unique ring to induce pressure in the eye. It helps to flatten the eyes and holds the eye in position.

• The placing of a lid speculum prevents the blinking of the eye during surgery.

• Again, doctors apply anesthesia and create microincision on the cornea to access the cataract using an ultrasonic hand instrument. However, doctors use laser technology to incise the cornea and microprobe to remove the cataract in some cases.

• Then the doctors remove the natural lens and fix the intraocular lens instead for clear vision.

• Doctors cover the eye with a bandage and, the injury due to the incision heal itself after several days.

Complications and Follow-Up Care of Intraocular Lens Implantation Surgery

The complications after the surgery are rare. Sometimes patients experience bleeding and pain in the eye. The affected area turned red and get swell after the implantation surgery. Other rare complications after the intraocular lens implantation surgery include;

• Sometimes the retina gets detached from the nerves after the surgery. It is a rare condition and requires a medical emergency.

• Inappropriate surgery results in the dislocation of the intraocular lens implants and moves out of the position.

• Loss of vision is a rare complication after the implantation surgery.

After successful implantation of intraocular lens, the patient does not need to replace it. However, the patient must take care of the following practices to ensure a successful intraocular lens implantation surgery.

• Avoid rubbing the eye.

• Use eyedrops only after cleaning the hands.

• Medications and better sleep is necessary for healing

Some of the disadvantages of the intraocular lens include;

• Patients with mono-focal lenses require additional eyeglasses while reading and working on the computer.

• Patients with toric intraocular lenses require eyeglasses for near vision.

By Prithvi Basak