Accommodating intraocular lens (Accommodating IOLs) are an advanced type of lens implant designed to correct presbyopia, nearsightedness and farsightedness. They can also offer a lens choice for cataract patients who need refractive cataract surgery. Accommodating IOLs are also used in people who don't have cataracts and want to reduce the need for reading glasses through lens-based vision correction surgery or refractive lens exchange (RLE).
During the treatment, the eye surgeon makes a small incision in the cornea to reach the eye lens, reduces it into small pieces and extracts them. He/she then inserts the accommodating IOL and places it into the right position. The implant becomes a permanent part of the eye.
Accommodating IOLs may transform cataract and refractive lens surgery because they can provide unaided near visual acuity without image degradation and optical aberrations.
Patients should discuss their vision needs and expectations of the lens implant with the surgeon. He/she will recommend the best option after reviewing the patient’s medical history and conducting a complete eye exam to ensure the patient is eligible for the procedure.
The surgeon also takes measurements of the corneal curve and the patient’s eye. The measurements are used to choose the right IOL and to set its focusing power.
Accommodating IOLs can be classified into two categories:
- Single-optic IOLs - This implant works by changing its position in the capsular bag which increases the active power of the lens but not its built-in power.
- Dual-optic IOLs- During accommodative effort, the two lens pieces increase their distance from each other which increases the productive power of the IOL. This design has an advantage over single-optic IOL because it needs less lens excursion to achieve a desired amount of accommodation.
Accommodation is a process which adjusts the eye’s focusing power enabling it to give clear vision at all distances, i.e., it offers a continuous range of vision with optimal near, intermediate and distance vision. The contraction of the ciliary muscles provides accommodation, which leads to a shift and a change in curvature of the natural eye lens.
With age, there is a reduction in the elasticity of the lens and a decrease in the ciliary muscle contraction which causes accommodation to decline. It creates a problem with near vision (presbyopia), a disorder affecting many people above the age of 40.
Other types of intraocular lens preserve all functions of the natural lens, except for accommodation. Accommodative IOLs are designed to restore accommodation. They are an artificial replacement for the natural eye lens. The lenses are designed to allow eye muscles to move the IOL backward and forward, adjusting the focus like a natural eye lens to provide near and distance vision.
For accommodating IOLs to work well, they should be placed in both eyes. Within six to twelve weeks after surgery on the second eye, the brain adapts to the IOL and the patient experiences vision improvement.
Each patient’s success with these implants depends on the size of their pupils and other eye health factors. So, the ability to read and undertake other tasks without contacts or eyeglasses varies from person to person. In most cases, accommodating IOLs reduce but do not end the need for contact lenses or glasses.
Accommodating IOLs are ideal for people with cataracts who because of their job, hobbies or lifestyle want a more natural range of vision. They reduce their dependence on near and intermediate vision glasses.
Accommodating IOLs in the toric model are also available for the correction of astigmatism.
Accommodating IOLs side effects may include:
- Corneal edema
- Retinal detachment
- Increased intraocular pressure
- Posterior capsular opacification (PCO)
- Decreased sharpness of vision (contrast sensitivity)
- IOL decentration - The implant moves out of position
- An after-cataract anywhere from weeks to years after surgery
- Glare or halos around lights, especially in dim light or at night
The eye surgeon implants the lens in a medical setting therefore overdose is unlikely to occur.