Cataract

Introduction

The opacification of the normal transparent lens is called cataract. The Latin word 'cataracta' means 'waterfall'. Imagine trying to peer through a sheet of falling water or through a frosted or fogged-up window.

History of Cataract treatment :

The earliest surgery treatment began in India. It was known as 'couching'. The sclera was incised. Then the lens was dislocated backward into the vitreous and out of optical axis.
This procedure was performed for more than two thousand years until the mid-eighteenth century. Great progress in cataract surgery has been made in recent years with the introduction of micro-surgical instruments, microscope and modern surgical techniques like phaco-emulsification. In the early stages of cataract development, all that is needed to correct your vision with glasses is a change in prescription. As the cataract develops and begins to affect your lifestyle, it needs to be removed. Cataract surgery, the most commonly performed operation, is safe and effective in 95% patients with enhancement in vision.

Methodology:

The procedure of cataract surgery by Phacoemulsification technique:

During this procedure, the surgeon will first create a small incision with an advanced diamond blade.
The surgeon will then peel off the front layer of your lens capsule.
Using ultrasound from small sophisticated instruments, the surgeon will break up your cataract into minute fragments.
The instruments then use gentle suction to extract these fragments out of the eye.
An intra-ocular lens is implanted to replace your natural lens. Diffeent types of Lenses:

Diffeent types of Lenses:

Anatomy of the lens:

Capsule
Cortex
TNucleus

The primary function of the bi-convex lens is to refract and focus light on the retina while remaining transparent. This transparency depends on the maintenance of structural (anatomic) & functional (physiologic) integrity.
The lens is 66% water,the least hydrated organ of the body. The remaining bulk is composed mainly of protein. It is devoid of any blood supply and derives its nourishment from the surrounding aqueous and vitreous.

Classification of cataracts:

Cataracts are classified as per their morphology (form and structure) and as per their maturity.

a) Morphological types:

Capsular : Focal thickening of lens capsule
Sub-capsular
Cortical : Opacification of cortical fibres
Capsular : Focal thickening of lens capsule

b) According to maturity:

Immature : Scattered opacities are separated by clear zones.
Mature : Cortex and nucleus become totally opaque.
Intumescent : The lens becomes swollen by absorbing water.
Hyper-mature Cataract : Mature cataract, which has become smaller and has a wrinkled capsule as a result of leakage of water out of lens.
Morgagnian Cataract : A Hyper-mature cataract, in which total liquefaction of cortex allows the nucleus to sink inferiorly.

Causes of cataract:

Age-related cataract :

The cataract occurs as a result of the natural aging process of lens fibres which become opaque over a period of time.

Traumatic cataract :

Due to a direct penetrating injury.
Concussion- Electric shock and lightning.
Ionizing radiation to ocular tumours.
Surgical trauma

Metabolic cataract :

Defect in body metabolism
Diabetes
Galactosaemia -inborn error of metabolism
Calcium disorders
Toxic cataract

Steroid-induced cataract :
This occurs as a result of excess intake of oral steroid or putting steroid drops in the eye.Drugs induced: Chlorpromazine, Miotics, Busulphan, Amiodarone, gold
Secondary cataract:
Here, cataract develops as a result of some other primary ocular disease such as chronic inflammation and glaucoma.

How do cataracts affect normal lifestyle?

One may not be aware that a cataract is developing if the size and location of the cloudy areas in the lens are not in the pupillary area. As the cataract progresses, there is deterioration of distant and near vision.

One may experience hazy, fuzzy and blurred vision.
Double vision may also occur when a cataract is beginning to form.
The eye may also be more sensitive to light resulting in glare and making night-driving difficult.
There may be a need to change the eye-glass prescription in the early stages, which may help temporarily.
As the cataract develops further, stronger glasses would no longer improve the vision.
This can lead to imbalance between the two eyes, which may cause headaches.
One may also experience poor night-vision, poor depth-perception, e.g. difficulty in getting downstairs.

Development of cataract :

It varies from person to person but as a general rule, most cataracts develop slowly over a period of time. A cataract can take months or even years to reach a point where it adversely affects vision.

Effects of cataract on normal lifestyle:

One may not be aware that a cataract is developing, if the size and location of the cloudy areas in the lens are not in the pupillary area.
As the cataract progresses, there is deterioration of distance and near vision.
One may experience hazy, fuzzy and blurred vision.
Double-vision may also occur when a cataract is beginning to form.
The eye may also be more sensitive to light resulting in glare and making night- driving difficult.
There may be a need to change your prescription eyeglass in the early stages, which may help temporarily.
As the cataract develops further, stronger glasses would no longer improve the vision this can lead to imbalance between the two eyes, which may cause headaches.
One may also experience poor night vision, poor depth perception, e.g. difficulty in getting downstairs.

Methods of evaluation of cataract :

Visual acuity :
Checking vision of both eyes unaided and aided with glasses and pin-hole vision to know the improvement as well as to get the general idea about the macular function of the eyes. This will help in prognostic evaluation of visual recovery after cataract surgery.

Intra ocular pressure :
If intra-ocular pressure increases as a secondary to cataract, surgery is needed to prevent further complications.

Slit-lamp examination :
To know the type of cataract along with its opacity, morphology and etiology or any associated ocular pathology.

Direct and indirect ophthalmoscopy :
Dense opacity (cataract will prevent retinal evaluation)

A-scan biometry:
To calculate the AL and IOL power for implantation In cases of mature cataract the posterior segment of the eye is evaluated.

Treatments for cataract:

No presently available medical treatment can prevent cataracts or reverse them once they develop.

The only treatment for cataract is their surgical removal.
The decision to operate is taken by the patient and the doctor together.
This decision is based on the degree to which the cataract is impairing vision and the effect it has on patient's lifestyle.
It is the decision only the patient and the doctor can make, as based on the individual's needs.
With modern advances in cataract surgery, one does not require to wait till vision drops to finger-counting.
The sooner the operation is done, the better are the results.

Two treatments options available for cataract:

Extra-Capsular Cataract Extraction (ECCE): is a conventional technique. It requires

The sooner the operation is done, the better are the results.
ECCE requires an incision of 10-12mm
The doctor removes the clouded lens in one piece.
Multiple stitches are required.
He implants a non-foldable lens.
Micro-incision cataract surgery: Phaco-emulsification is a modern technique.

Phaco-emulsification is the latest technology in cataract surgery. It is a micro-incision stitch-less operation, where the cataract is emulsified by ultrasound energy, liquefied and sucked through the phaco-emulsifier probe. Then a foldable intra-ocular lens is implanted in the eye permanently.

Benefits:

It is least traumatic form of cataract surgery with early rehabilitation and recuperation.
Vision restoration is possible in a short period of time. (pictures to be placed here)
The operation is not traumatic to the eye.
It is a day-care procedure without the requirement of hospitalization overnight.
The operation is performed by instilling local anaesthetic drops and without giving any injection in most cases. Hence no patch is necessary after the surgery.
This procedure offers the least chances of infection
Healing and recovery are quicker.
The patient gets good quality vision within twenty-four to forty-eight hours.
It involves minimum post-operative precautions.
The patient can resume professional work in the shortest possible time.
One may need to wear glasses only to fine tune one's vision.
Glasses will be necessary for clear near-vision.
One can reimburse the cost for the surgery through Mediclaim.

Methodology:

It is a micro-incisional stitch- less operation.
The ultra-sound energy emulsifies the cataract .
It is liquefied and sucked through the phaco-emulsifier probe.
Then the surgeon implants a foldable intra-ocular lens in the eye permanently.

It is the least traumatic form of cataract surgery with early rehabilitation and recuperation. Vision restoration is possible in a short period of time.

Advantages of phaco-emulsification:

The operation is atraumatic to the eye.
It is a day-care procedure without the requirement of hospitalization overnight.
In most cases, the surgeon performs the operation by administering local anaesthetic drops without giving any injection .
Hence no patch is necessary after the surgery.
Least chances of infection.
Quicker healing and recovery.
The patient gets good quality vision within 24-48 hours.
Minimum post-operative precautions.
The patient can resume professional work in the shortest possible time.
One may need to wear glasses only to fine-tune one's vision, although glasses will be necessary for clear near- vision.
One can reimburse the cost for the surgery through Mediclaim.

Lens implants:

During cataract surgery, the natural lens of the eye that has turned opaque is removed, resulting in loss of focusing power of the eye. This situation would be parallel to clicking a photograph without a camera lens-the picture would be extremely blurred. When the natural lens of the eye is removed an artificial implant is placed in the eye.

Intra-Ocular Lens (IOL):

Intra-ocular lenses may be rigid or flexible. The flexible IOLs are made from either Silicone or Polydroxymethacrylate so that they can be folded to allow insertion through a much smaller incision as compared to rigid IOLs.

SofPort® AO Lens with Violet shield Technology.
Description:
The new SofPort AO lens with violet shield technology is designed to be aberration free and thus reduces spherical aberration for better vision quality relative to standard spherical IOL's.

Suitability:
Its optical performance is unaffected by optic decentration or pupil size due to uniform center to edge power. It is more predictable and repeatable outcomes with a large patient population can be expected.

Benefits:
The SofPort lens helps preserve retinal health by blocking the more harmful violet light without the low vision compromise that is associated with blue blocking technologies.

Akeros AO Micro incision Lens.
Description:
This advanced micro incision lens offers aspheric aberration free sight and is designed for improved quality of vision. The lens can be implanted with a 1.8 mm incision and its shape with a four point Fixation design offers three dimensional stability.

Suitability:
Since the lens has uniform power from center to edge it can offer predictable refractive outcomes for all patients.

Benefits:
Since the lens has uniform power from center to edge it can offer predictable refractive outcomes for all patients.

Aspheric lenses for improved quality of vision
1.8 mm incision to help quicker recovery with and lesser chances of complications
Uniform power to optimize vision for all patients
Aberration free lens to preserve the depth of field.

Crystalens
Intraocular lens

Description:

Crystalens , is a single-focus accommodating intraocular lens. It was developed to address the loss of intermediate and near focusing ability. It is manufactured from a proprietary and specially formulated solid silicone called Biosil . Crystalens is a cataract replacement lens that works naturally with your eyes' muscles to give you the quality of vision you enjoyed when you were younger.

Distinction:

The revolutionary design element that makes Crystalens the state-of-the-art replacement lens are "hinges" which are designed to allow the lens to move, or accommodate to focus on objects near, far and all distances in-between seamlessly.

Suitability:

Crystalens is normally an option after the removal of cataract. It is now possible for your surgeon to replace your lens with Crystalens to help you regain vision not only at distance, but also intermediate and near objects-without dependence on glasses.

Benefits:

You will be able to do most of the daily tasks as usual without dependence on glasses or contact lenses.

Multi-focal Intra-Ocular lenses: Artificial Lens Implants
IOLs originally were meant to give freedom from glasses. However with the best of results the problem of near vision was not addressed. To address this problem surgeons tried to give monovision where the dominant eye was corrected for distance and the non-dominant eye for near vision using monofocal IOL.
This led to This led to the origin of multifocal IOLs or the IOls that focused far & near objects at the same time on the retina. The oldest designs were the 2 zone or 3 zone Bull's eye lenses. These lenses were PMMA lenses. Visual outcome was highly pupil dependent nd depending on the pupil size, the near or distance zones were blocked thus preventing the lenses from functioning as true multifocals.
The next generation of Multifocals used the principle of "Diffraction"to create 2 foci for distance and near. The basic refractive power for distance was provided by the anterior surface of the IOL and the diffradtive posterior surface design gave near vision. 41% light was focused for distance and 41% for near. These lenses are pupil independent due to diffractive rings but they continued to have poor contrast function and problems of glare and haloes under dim light conditions due to annular zones.
The next improvement came as Foldbale Multifocal IOLs. They have 5 concentric zones on its anterior surface. The light distribution was 50% for distance, 37% for near and 15% for intermediate distance. This lens had a ideal pupil size of 3.5mm and so proved unsuitable in Indian eyes that had small pupil size. The patients had lowered contrast sensitivity and increased perception of haloes. The modification of the original Silicon lens is Acrylic Foldable Rezoom lens. It has 5 zones 1, 3, & 5 are for distance and zones 2 & 4 for near. The zones are so modified that 60% of light is focused for distance & 40% for near and intermediate. Result show 80% of patients have good near vision but the lenses do not completely eliminate need for near glasses. The lens has modified edge design to reduce haloes and edge glare and aspheric transition between zones to reduce glare and give better intermediate distance.

Benefits:
They are far more functionally useful than conventional mono-focal implants as they obviate the need for spectacles.

OLC offers you Multi-focal IOLs from Technics and Restor.
Tecnis ZM001 IOL
This is diffractive IOL with anterior prolate surface that minimizes the increasing spherical aberration of the ageing eye. Thus it improves the quality of vision. The posterior diffractive surface gives near addition of +4.0D and adds in near vision. This lens was found to give good near vision in both bright & dim light conditions.

ReSTOR ® Intraocular Lens

Description
ReSTOR ® - Apodized Diffractive Optic Posterior Intraocular Lens is a permanent Intra Ocular lens. It is convex on both sides and made of a soft plastic. ReSTOR is folded and inserted into the eye through a tiny incision smaller than the optic diameter of the lens. After insertion, the lens gently unfolds and corrects vision. The lens has supporting arms that maintain proper positioning within in the eye.

Distinction
The ReSTOR ® Intraocular Lens replaces the natural lens. It has a patented optic design using apodization, diffraction and refraction technologies. The apodized diffractive optic design gives it the ability to focus light correctly on the retina for images at various distances without mechanical movement of the lens.

Apodization is a gradual reduction or blending of the diffractive step heights.
This unique technology optimally manages light energy delivered to the retina because it distributes the appropriate amount of light to near and distant focal points, regardless of the lighting situation.
Apodized diffractive optics are designed to improve image quality while minimizing visual disturbances. The result is an increased range of quality vision that delivers a high level of spectacle freedom.

Suitability
ReSTOR is indicated for adult patients with or without prespyopia who desire near, intermediate and distant vision.

Benefits

Increased independence from glasses and contact lenses
Ability to have normal distant as well as intermediate and near vision

Rezoom(lens)
ReZoom is a new, second generation multifocal refractive IOL that lets hyperopic patients resume their lives with a full range of vision in varying light conditions.
ReZoom balanced view optics distributes light over 5 optic zones so that each lens has distance dominant central zone for distance vision in bright light conditions when the pupil is dilated. A large distant dominant third zone plus a distance - dominant fifth zone provide good vision in moderate to low light conditions as the pupil expands. ReZoom also offers the +3.5 dipoter near add that is needed by most adults over 50.

Suitability
ReZoom is a new, second generation multifocal refractive IOL that lets hyperopic patients resume their lives with a full range of vision in varying light conditions.

Benefits

ReZoom's proportioned zones prReZoom's proportioned zones provide good visual function across a range of distance in varying light conditions.
ReZoom offers the +3.5 d near vision needed by most adults over 50.
The 3 piece design of the lens provides continued centration even in situations where one piece lenses may decenter and require repositioning or removal.

ReZoom Multifocal Intraocular lens
Description
The ReZoom Multifocal Intraocular Lens is an option for the treatment of both cataracts and presbyopia. It is designed to provide patients multifunctional vision if they desire for greater independence from glasses or contacts. The ReZoom Multifocal Lens has a patented lens design called Balanced View Optics Technology. This lens design creates multiple focal points so patients can see well at a variety of distances, be it near, mid-distance, or far.

Distinction
The ReZoom Multifocal Lens has carefully proportioned visual zones that provide patients with vision at varying distances. Each ReZoom Multifocal Lens is divided into five different zones with each zone designed for different light and focal distances. Unlike other earlier multifocal lens designs, the ReZoom Multifocal Lens has proportioned the size of its zones to provide for good vision in a range of light conditions. Some zones have been designed to offer greater low light-distance vision during night driving whereas others provide better bright light-near vision for close vision activities.

Suitability
ReZoom is indicated if you are suffering from a cataract condition and have the following problems

Difficulty reading
Difficulty seeing close objects
Difficulty seeing to drive, especially at night
Changing glasses prescriptions
Needing bifocals

Benefits:

Ability to read without contacts or spectacles
Ability to see close, intermediate and distant objects

Indications for cataract surgery:

Visual improvement.

Medical indications are those in which the presence of a cataract adversely affects the health of the eye e.g. lens-induced glaucoma.
Cosmetic indications: A mature cataract in an otherwise blind eye is removed to restore a black pupil.

How do I decide whether to have a cataract surgery?

After you inform the doctor about how your cataract affects your vision and your life, you and your doctor can decide about the corrective course of action.

I do not see well enough to do my best at work.
I do not see well enough to do things I need to do at home.
I do not see well enough to do things I like to do (e.g. watch T.V, sew, play cards, go out with friends)
I am afraid I will bump into something or fall.
I am not as independent as I would like to be.
My glasses do not help me see well enough.
My eyesight bothers me a lot.
Driving is a problem - there is too much glare from the sun during the day-time and headlights at night.

Benefits of cataract surgery:

Cataract surgery gives you back the ability to drive, read and continue work. You can also get back to your social activities and hobbies.
Risks of cataract surgery:
Some of the possible complications are:

High pressure in the eye.
Blood collection in the eye.
Infection.
RD (Retinal Detachment).
Swelling / clouding of the cornea.

Instructions for Surgery

Freedom from blurred vision gives you the freedom to enjoy your life to its fullest extent!!
What you should know or do before going for surgery:

Know your general health status.
Treatments related to other active diseases before surgery.
Pre-operative investigations like blood tests, ECG and glucose should be recorded.
Carry out the pre-operative instruction as per the scheduled date and time given by your doctor.

Pre-operative instructions:

Have light breakfast four hours before arriving at the hospital.
Use the eye drops as instructed three days prior to the date of the surgery and in the morning of the day of surgery in the eye which is to be operated.
Take the dose of regular medication which you are already taking.
Take head bath and dress comfortably.
Visit the clinic accompanied one or two persons at the most.
Carry your case papers, reports, sunglasses and necessary medication.
Register at the reception counter for admission.
Read and sign the consent form for the operation and take instructions form the optometrist.
If for some reason you have any questions, the doctor or one of the optometrists will answer them before the surgical treatment is begun.
Stop taking blood-thinning or anti-inflammatory medications including Aspirin three days prior to the day of your surgery.
Plan to have someone drive you home following surgery.
Plan to have a parent or legal guardian with a disabled person.
If there is any change in appointment, call up at the centre and inform a day prior to the date of operation.
Wear comfortable clothes.
Do not apply make-up or wear jewellery.
Do not carry expensive goods with you.

Area of operation :

The assistant will take you to the area where you would be prepared for the surgery. You will change into surgical clothes, cap, etc.
Pre-operative medication will be administered by way of anaesthetic drops, injections or sedatives if necessary. One person will help you to enter the operating room and lie down on the operation table, you will always have someone by your side to assist and help you during the operation.

Surgical wash:
The two eyelids will be carefully cleaned with the anti bacterial solution and drops will be put to clean the eyes and to make the area sterile during the surgical procedure.

After surgery:
The assistant will help you to leave the operation theatre and go to the recovery room where you will need to rest for some time. After this, the person who has accompanied you, can take you home to rest.

Good vision is necessary to enjoy your life to its fullest extent!!