What are lenses or IOLs?
An intraocular lens (IOL) implant is a tiny, synthetic lens made of plastic, silicone, or acrylic that is used to replace the cataractous natural lens. The IOL implanted is designed to last indefinitely. Side vision and image size are normal and there is no discomfort. There is also no foreign body to irritate the surface of the eye. This is currently the most commonly-used option.
Nowadays we have a wide array of lenses to choose from. The choice of lens could depend upon the patient’s budget, requirement, life-style and the desire to see the very best possible. The artificial lens chosen especially for your eye will give you clear vision for the rest of your life. Your eye surgeon will advise you on the most suitable lenses available and you will have a choice; for example you may opt for a lens that gives you clear vision in the distance and near (reading), called a multi-focal lens, which could mean minimal or no dependence on specs – for life!
Vision in cataract and after treatment
Normal Vision
Astigmatism
Cataract Vision
Treatment with monofocal lens
Treatment with multifocal/toric lens
Normal Vision
Astigmatism
Cataract Vision
Treatment with monofocal lens
Treatment with multifocal/toric lens
Types of Lenses
Types of Lenses
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Toric lenses and astigmatism
What is Astigmatism?
Normally, the cornea and lens are smooth and curved equally in all directions. This helps to focus light rays sharply onto the retina at the back of your eye. If your cornea or lens isn’t smooth and evenly curved, light rays aren’t refracted (bent) properly. This a refractive error.
When the shape of cornea or lens is distorted, it is called astigmatism. In either case, your vision for both near and far objects is blurry or distorted.
Correcting Astigmatism using Toric Lens
If you have astigmatism, then only Toric lens may help to reduce your need for glasses for distance or near vision. The most advancement IOL in this category is now also available as multifocal Toric IOL.
Vision with Astigmatism
Cataract Vision
Vison with non-toric lens
Vision with multifocal toric
Foldable lenses and its advantage
Intra Ocular Lens (IOL) are the lenses which is placed inside the eyes by removing the cataract affected natural lens.
There are two types of IOL available; non-foldable (rigid) and foldable.
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- Foldable Lenses (IOL): The next step in technological advancement is the development of foldable lenses. These are made of a soft acrylic material which can be folded or rolled so as to be injected through a very small incision into the eye. Once inserted at the right place, the IOL unfolds and stabilizes in the eye to give a lifetime of clear vision.
Advantages of Foldable IOL- It is used in PHACO surgery
- Foldable IOL is made up of soft Acrylic material which is more bio-compatible.
- Needs very small incision for insertion in the eye. Usually the incision size is 2 mm or less.
- The chances of induced astigmatism become much less due to much smaller incision.
- Very short healing time.
- Chances of infection are minimal.
- Foldable Lenses (IOL) could be either MONOFOCAL or MULTIFOCAL.
- Foldable Lenses (IOL): The next step in technological advancement is the development of foldable lenses. These are made of a soft acrylic material which can be folded or rolled so as to be injected through a very small incision into the eye. Once inserted at the right place, the IOL unfolds and stabilizes in the eye to give a lifetime of clear vision.
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Multifocal Lenses (IOLs)
These IOLs have revolutionized existing state-of-the-art cataract surgery. Multifocal IOL helps to achieve the ultimate goal of independence from spectacles. These advanced technology IOLs are a newer type of lens that has multiple focal points and reduces or eliminates the need for eyeglasses or contact lenses after cataract surgery.
80% of patients who get these lenses will never need glasses for any activity. Of those 20% of patients who need glasses for certain activities, do so for very fine near work done for prolonged period of time. If the patient has astigmatism then they will need Toric IOLs to completely get rid of spectacles. More over the near glasses needed are of much less power than those needed by patients with monofocal IOL.
Normal Vision
Cataract Vision
Vision with Multifocal Lens
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Monofocal Lenses (IOLs)
Presbyopia
Presbyopia is the loss of your eyes’ ability to focus on nearby objects. A person with presbyopia could not see the near object clearly.
Monofocal IOLs
These IOLs provide a set focal point and can fix your vision for one distance only. It corrects the cataract but does not correct presbyopia. In such cases, the patient does not require to use spectacles to see far objects but is dependent on progressive bifocals spectacles for near vision.
If you do not want to use spectacles for near or distance vision post cataract surgery, based on diagnosis, you may choose Multifocal or Toric lenses.
Normal Vision
Cataract Vision
Vision with Monofocal Lens
Non-foldable lenses
Intra Ocular Lens (IOL) are the lenses which is placed inside the eyes by removing the cataract affected natural lens.
There are two types of IOL available; non-foldable (rigid) and foldable.
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- Non-foldable Lenses (IOL)Are made of a hard-plastic material (PMMA), are bigger in size & bigger incisions need to be made to insert them. These are the basic and the most initial IOL developed. As these IOLs cannot be folded so an incision (cut) as big as the IOL is mandatory for implantation in the eye. Technologically these are most basic of lenses, low in price and could only be monofocal.Limitations of Non – Foldable IOL:Most of the limitations arise due to the necessity of putting a larger incision to implant this type of IOL. With non-foldable IOL, the surgical incision has to be at least as big as the IOL, which is 5.5-6.0 mm –
- It is used in SICS surgery
- The healing time is prolonged.
- The chances of infection become higher.
- The chances of induced astigmatism become higher with bigger incision.
- The non-foldable IOL are overall less in diameter than foldable IOL so the chances of glare increase because of smaller IOL
- Since multifocal option is not available in non-foldable lenses, the patient will need spectacles for near vision
- Non-foldable Lenses (IOL)Are made of a hard-plastic material (PMMA), are bigger in size & bigger incisions need to be made to insert them. These are the basic and the most initial IOL developed. As these IOLs cannot be folded so an incision (cut) as big as the IOL is mandatory for implantation in the eye. Technologically these are most basic of lenses, low in price and could only be monofocal.Limitations of Non – Foldable IOL:Most of the limitations arise due to the necessity of putting a larger incision to implant this type of IOL. With non-foldable IOL, the surgical incision has to be at least as big as the IOL, which is 5.5-6.0 mm –
You must know
IOLs comes with different power. Only a state-of-the-art Biometer equipment can calculate the correct IOL power considering all types of eye conditions.
Did you know?
Vimla Ramkrishna Bajaj Eye Hospital has most advanced Optical Biometer equipment Lenstar 900, Haag Streit, USA.
| Treatment of different types of eye conditions | |||
|---|---|---|---|
| Types of IOLs | Cataract | Presbyopia | Astigmatism |
| Monofocal | Yes | No | No |
| Multifocal | Yes | Yes | No |
| Monofocal Toric | Yes | No | Yes |
| Multifocal Toric | Yes | Yes | Yes |
