Intraocular Lens – A Complete Guide
An intraocular lens is implanted in the eye once your natural lens which has turned opaque due to the removal of cataract, to restore your vision to optimal. With advances in available technology for cataract surgery, the kind of intraocular lenses, called IOLs, have also undergone a revolutionary change. The first IOL that was implanted in the human eye, by Sir Harold Ridley in 1949, was made of acrylic called Perspex.
Intraocular lenses were approved as “safe and effective” in the USA by the Food and Drug Administration (USFDA) only in 1981. From then to now, the kinds of lenses that are available for implantation has been nothing short of a revolution for cataracts treatment.
Types of Intraocular Lenses (IOLs)
The two most common types of lenses are:
- Anterior Chamber Lenses (ACIOL): These lenses are placed on top of the iris, the brown part of the eye. It is not the physiological position of the natural lens of the eye, and this type of lens is not the preferred IOL after non-complicated cataract surgery. ACIOLs are implanted in case the posterior capsule of the lens is deficient or damaged.
- Posterior Chamber Lenses (PCIOL): These lenses are tucked into the place over the residual posterior capsule in the physiological position of the natural lens of the eye and are the preferred lenses.
The rest of this article will discuss the major types of advanced PCIOLs available for implantation after modern cataract surgery, namely, phacoemulsification, Microincision cataract surgery or Femtosecond laser cataract surgery. These lenses are collectively called premium IOLs.
Types of Premium IOLs
Premium IOLs are of three broad categories:
1. Monofocal Lenses
Monofocal lenses, unlike the natural lens of the eye, can only restore vision for one distance, that is for distance, or for near. The power of the monofocal lenses is usually calculated so that the patient does not need glasses for distance vision. After having a monofocal lens implantation, you will need reading glasses or even bifocals which are glasses for both distance and near, depending on your preexisting refractive error (especially astigmatism). Below are the various types of monofocal lenses:
- Aurium (Monofocal): Aurium monofocal lenses are manufactured by Medennium(USA). These lenses are photochromatic, which means they become lightly tinted during daytime or bright light and thus prevent harmful UV. Under normal room lighting conditions, these lenses become transparent.
- Acrysof IQ (Monofocal): Acrysof IQ is an imported monofocal lens manufactured by Alcon (USA). These lenses provide excellent vision for distance. For near vision, however, a person may require additional reading glasses. This lens contains a yellow pigment chromatophore which blocks harmful UV rays and the blue rays from entering the eye and damaging the retina.
- Aurovue(Monofocal): An Indian Company – Aurolab manufactures Aurovue lenses. These lenses are considered as entry-level options for cataract surgery and are recommended for somebody on a low budget.
- Akreos AO(Monofocal): Akreos AO are similar to Aurovue lenses. However, these are imported lenses and are manufactured by Bausch & Lomb (USA).
- Acrysof SP(Monofocal): Acrysof SP is imported monofocal lens, manufactured by Alcon (USA). These lenses are also preferred in Diabetic Patients. It is also a recommended option for somebody opting for a monofocal lens in Regular Phaco surgery.
2. Multifocal Lenses
Multifocal IOLs are lenses which offer an acceptable restoration of vision for both near and distance. While choosing an IOL, it is important to remember that multifocal lenses provide you freedom from glasses for both near and distance, and can be customized to your active lifestyle. However, your doctor will discuss with you the apparent drawbacks of these lenses, namely glare, and a decrease in contrast sensitivity. In case you do not want to wear glasses for near or distance and do not want to go ahead with the added expense of a multifocal IOL, your doctor will discuss monovision with you. Following are the best multifocal lenses:
- Tecnis Symphony (Multifocal): Tecnis Symphony is a multifocal lens manufactured by Abott (USA). This lens provides excellent distance and intermediate vision (computer working).
- Zeiss Trifocal (Multifocal): Zeiss trifocal lenses are multifocal type lenses manufactured by Zeiss (USA). These are the only lenses which provide excellent vision for near, intermediate and distance.
- iDiff (Multifocal): iDiff lenses are multifocal lenses manufactured by Care Group. These lenses provide good vision for near and distance, which means that a person can easily carry out regular day to day activities with distance vision and also do near work such as reading and writing comfortably without use of additional spectacles. iDiff Lenses, however, do not correct intermediate vision.
- Tridiff (Multifocal): Tridiff lenses are multifocal lenses manufactured by Care Group. These lenses provide good vision for near, intermediate and distance, which means that a person can easily carry out regular day to day activities with distance vision, also do intermediate distance work such as working on the laptop and also carry out near work such as reading and writing comfortably without the use of additional
- Alcon Pantopix (Multifocal): It is the largest introduction in multi-focal lenses. The lens is able to provide excellent vision in for distance, immediate and near.
3. Toric Lenses
An eye can have two types of power, spherical power which is because of the natural lens within the eye and cylinder power which is because of the dissymmetry in the curve of the cornea. Monofocal and Multifocal Lenses can only correct the spherical component of the eye leaving behind the cylinder power which has to be later corrected by additional prescription glasses. Toric Lenses can correct both spherical and cylinder components of the eye. Toric lenses are recommended if you have a high pre-existing cylinder or astigmatism in your eye. Below are the recommended Toric lenses:
- Acrysof IQ (Toric): These lenses are designed to correct astigmatism at the time of cataract surgery. This lens is manufactured by Alcon (USA).
- Acrysof Toric (Toric): These lenses have all the properties of Acrysof IQ along with cylinder correction
- Zeiss (Toric): The lens is manufactured by the German company Carl Zeiss and is one of the benchmarks in superior cylinder correction.
Which is the best IOL for you?
In medicine, like life, there is no single best answer. Your doctor will discuss with you the potential benefits of each of these lenses, and help you select the one best suited for your lifestyle and visual needs, as well as your expectations from the cataract surgery.
Lifestyle and priorities: In case you have a very active lifestyle that involves a lot of precise focusing outdoors, like golf, you may compromise your near vision but not your distance vision. If you travel a lot, you might prefer to not be dependent on glasses at all, preceding a bit of precision for both near and distance vision. On the other hand, if you enjoy sewing or embroidery, you will want perfect near vision.
Pre-existing diseases: In case of certain eye diseases like advanced glaucoma, corneal disorders or age-related macular degeneration, you may not be a good candidate for specific lenses, like the multifocal lens. Your eye doctor will perform a comprehensive eye exam and discuss its results and implications with you, to help you choose the best possible lens for your eye.
Costs: These lenses are more expensive than traditional IOLs, adding an incremental value to the cost of cataract surgery. The premium lenses come at a price that is usually not covered by insurance companies.
The doctors at Eye7 Chaudhary Eye Centre are well versed in the use of premium IOLs following cataract surgery in Delhi and have had the experience of implanting thousands of these lenses. Your eye doctor will be happy to discuss all the options available and help you choose the best choice for your eye health, and visual needs.