An intraocular lens (or IOL) is a small artificial lens implanted in the eye in place of the cloudy natural lens (cataractous lens) during cataract surgery.
The natural crystalline lens bends light rays that enter the eye and helps us to see. When this clear lens becomes cloudy with cataract formation, things look blurry, hazy, or less colorful. Cataract surgery involves the removal of this cloudy lens and replacing it with a clear intraocular lens to improve vision.
IOLs are available in different focusing powers, which are individualized by your ophthalmologist based on your eye’s length and curvature of the cornea. With advances in cataract surgery technology, intraocular lenses have also undergone a revolutionary change.
Different types of IOLs are available based on the
- Size and shape ( biconvex, aspheric, square edge IOLs)
- IOL material ( rigid PMMA, soft acrylic, silicone, hydrogel, Collamer IOLs)
- Type of optical correction ( Monofocal, multifocal, accommodative, phakic IOLs)
- Based on physical flexibility and a variety of cataract surgery ( foldable and Non-foldable IOLs)
- Based on U.V. absorption ( blue light filtering IOL, which protects the eyes from harmful ultraviolet rays)
- Based on the site of lens implantation within the eye ( anterior chamber and posterior chamber intraocular lenses)
Choosing the best IOLs type for cataract surgery
The advanced posterior chamber IOLs available for implantation after modern cataract surgery, namely, phacoemulsification, Microincision cataract surgery or Femtosecond laser cataract surgery, are collectively called premium IOLs. You have the freedom to choose from a large pool of premium IOLs. The selection of the best intraocular lens depends on many factors, including lifestyle, specific visual needs, pre-existing diseases, and cost.
The following is an overview of premium IOLs currently available.
These are the most common type of lenses used with cataract surgery. Monofocal lenses are designed to restore vision for only one distance, for distance or near. Most people have them set for clear distance vision. Then they wear reading eyeglasses for reading or close work or even bifocals which are glasses for both distance and near for patients with preexisting refractive error ( especially astigmatism).
E.g., Acrysof IQ, Acrysof SP, Aurovue, Akreos AO.
Multifocal IOLs (MFIOLs)
These intraocular lenses are designed to restore vision for both near and distance and thus reduce dependency on glasses by providing a good clear vision for both distance and near. However, the apparent drawbacks of these lenses are glare and a decrease in contrast sensitivity.
Eg : Technis Symphony, Zeiss Trifocal, Alcon Panoptix.
Extended Depth of Focus IOLs
These lenses create a single elongated focal point to enhance the depth of focus. It enhances the sharpness of vision at near, far, and intermediate distances. These are designed to reduce glare and halos, as reported in MF IOLs.
Accommodating IOLs are premium intraocular lenses that expand the range of clear vision with both an aspheric design and flexible “haptics”. This flexible haptics allows the accommodating IOL to move forward slightly when looking at near objects, which increases the eye’s focusing power enough to provide better near vision than a conventional monofocal lens but may not provide the same level of magnification for near vision compared to MFIOL.
For people with high preexisting cylinders or astigmatism, toric Lenses can correct the eye’s spherical and cylinder components.
E.g., Acrysof IQ (Toric), Zeiss (Toric).
Aspheric IOLs closely match the shape, and optical quality of the eye’s natural lens, providing sharper vision with good contrast sensitivity, especially at night.
Monovision is the technique of fully correcting the refractive error of one eye and making the other eye mildly near-sighted. In this scenario, the fully restored eye sees distant objects clearly (but cannot see very well up close without glasses), and the mildly near-sighted eye sees very well up close without glasses (but not so clearly far away). Any combination of premium IOLs can be used for monovision cataract surgery.
Types of IOL materials
Intraocular lenses can be manufactured from different materials. The type of material determines the flexibility of IOL. All lens materials discussed provide excellent optical quality and a good safety record.
Non-foldable or Rigid IOLs
Polymethylmethacrylate (PMMA) is the material used for non-foldable IOLs. Because PMMA is rigid, these lenses do not fold and require a larger incision implanted.
Foldable IOLs comprise materials flexible enough to allow the lens to be rolled, compressed, or folded in half. This property enables these IOL to’s to be introduced through a much smaller incision than their non-foldable PMMA counterparts. There are three classes of foldable lens materials – silicone, hydrophobic acrylic, and hydrogel.
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FAQ about IOLs
How long will the IOLs last?
IOL is fixed permanently inside the eye; hence it cannot fall out, does not require cleaning, does not change the appearance of the eye, produces no sensation, cannot be felt by the patient and will never cloud.
Can the IOL be removed and replaced?
Although rare, the IOL can be removed and replaced, and surgery can be associated with pros and cons. The most common reason would be the incorrect power of IOL, despite all of the preliminary calculations. Another reason would be IOL displacement from its position inside the eye.
Does having an IOL mean that I won’t need glasses anymore?
Not exactly. The conventional intraocular lens is a single, fixed focus lens. It cannot give distance focus one moment and near focus the next. Following cataract surgery, patients need to wear eyeglasses for reading or close work or even bifocals which are glasses for both distance and near for patients with preexisting refractive error ( especially astigmatism).
Does the multifocal IOL take the place of eyeglasses?
The multifocal IOL has its pros and cons. Although many of these patients do not seem to need spectacles, some still require spectacles most of the time for reading. Patients who have opted for multifocal IOLs can have better vision than those who opt for conventional IOLs.
Does the IOL protect from U.V. rays of the sun?
All premium IOLs are coated to provide U.V. protection at all times. Patients may choose to wear sunglasses for extra comfort.
If I previously had LASIK, R.K., or other refractive surgery, can I still have an IOL?
Yes. But it has to be kept in mind that prior refractive surgery causes significant surgical alteration in the corneal shape. Because of this, the corneal measurements used to calculate the IOL power become wildly inaccurate, significantly impairing the IOL power selection process. Prior records from exams immediately before and after the refractive surgery are helpful in such cases. Despite this, estimating the required IOL power is still very difficult.
Need cataract surgery?
If you are someone who feels they require cataract surgery and can’t seem to find the perfect place to get one done. Then, you need not look further; PVRI has the answer to all your needs.
PVRI is a not-for-profit, super-specialty eye hospital in Secunderabad, Hyderabad. PVRI has a team of highly trained professionals equipped with the best-in-class equipment to deliver equitable eye care for all sections of society.