Human eye has a natural lens which is normally transparent and forms a clear image of the outside world in the eye. When this lens develops haziness / opacity the sight is decreased or may be completely lost - this is called cataract.
What causes Cataract?
Cataract may develop at any age - right from birth to old age - but is most commonly seen in the old after the age of 60 years. By the age of 90 years almost 98 % of people have had cataract.
Cataract at old age is mostly caused by normal ageing process. When seen at younger age, it may be a resultr of various disease processes like trauma, uveitis, radiation ,diabeties, infections and many more.
What are the symptoms?
The most important symptom of cataract is a decrease in vision / sight for distance & / or near objects. Other features can be decrease vision in bright or low light, decreased contrast, glare, altered colour appreciation, seeing many images of one object, rapid changes in the number / power of glasses, or sometimes pain, redness and watering. In advanced cases there is complete loss of sight and pupil becomes pearly white in colour. However, none of these symptoms are seen exclusively in cataract.
What should one do?
The first thing a person must do on experiencing any of these symptoms is to consult an eye surgeon (Ophthalmologist) giving details of ones symptoms and getting ones eyes thoroughly examined. Answers to the following questions should be sought :
Do I have cataract ?
What is the cause of cataract in my eye ?
What are the treatment modalities available ?
What treatment would be most suitable for me ?
What is the expected outcome of the treatment/surgery in my case ?
What are the risks involved and possible complications ?
How early should I get operated ? What does the surgery involve in terms of time and expenditure ?
Do I have any other eye disease ?
Once it is decided that the patient has cataract, the treatment is essentially surgical. The only question that arises is when? The decision is patient’s - whenever the patient feels his vision has decreased to a level where he finds it difficult to carry on his routine daily activities. He can get operated (no longer is it required for the cataract to become mature). However, in certain cases where there are associated complications or potential risks of complications, an early (even urgent) operation may be required - here the advice of consulting eye surgeon should be followed.
The operations done for cataract are the following (the list includes only established standard procedures) :
Phacoemulsification with foldable Intraocular Lens (IOL) implantation (No-Stitch Surgery).
Extra-capsular Cataract Extraction (ECCE) with or without Intra-ocular Lens (IOL) Implantation.
Intra-capsular Cataract Extraction (ICCE).
Pars Plana (PP) Lensectomy.
In Phacoemulsification the incision is smaller (3.2 mm) and the nucleus of the lens is converted to a pulp using high frequency sound waves and sucked out. Then a foldable IOL is inserted through small incision and positioned into capsular bag or the incision may be enlarged and non-foldable IOL may be implanted (although sacrificing the advantage of small incision). The main advantages of this operation are early rehabilitation and decreased occurrence of high astigmatism (cylindrical power in glasses), though the final outcome after a few months is the same in both the procedures. All these operations are done under local anesthesia (injections of anesthetic drugs around the eye) or topical anesthesia (using only drops) which makes the eye and surrounding area numb / without sensation, and the patient although conscious does not feel any pain. The general anesthesia, which has its own risks, is used only in children and uncooperative patients.
ECCE with IOL implantation is the conventional procedure. It involves making an incision (about 6-8 mm) at the edge of cornea (junction of black with the white of the eye in the upper part) followed by making an opening in the capsule of the lens. Through these openings the nucleus (hard portion) of the lens is expressed and cortex (soft portion) of the lens is sucked out. IOL is inserted and positioned either inside the capsular bag or over the capsule (if the capsular support is deficient then IOL is positioned in the anterior chamber or may not be implanted at all).The incision is then sutured (stitched) using micro-fine polymer thread (# 10.0 or finer). In most cases these sutures are not required to be removed.
Intraocular Lens (IOL)
Intra-ocular Lenses (IOL) are small (5-7 mm) lenses made of a soft polymers viz., silicone, acrylic or PMMA and are implanted inside the eye in place of natural lens. The greatest advantage of IOL is a clear wide field of vision and the fact that the patient does not have to constantly wear thick glasses. However, glasses with low power may be still be required to be worn especially for reading distant and near small print. The reason being that unlike natural lens the IOL has a fixed power (estimated by doing Ultrasound of the eye) which is usually adjusted such that the mid-range or routine viewing distances are seen clearly, and for distances closer or further low powered glasses may still be needed.. Since the IOL stays in the eye lifelong therefore there should not be any compromise on the quality of the IOL. Indian IOLs, though structurally quite good, are not yet optically comparable to imported brands (e.g. Bausch & Lomb, Pharmacia, ORC, Domilens, Allergan, Iolab, Hoya, Alcon, Corneal, etc.)
Multifocal Foldable IOL
A recent advance in the field of cataract surgery is introduction of Multifocal Foldable Intraocular Lens (Available lenses are Rezoom and Technis Multifocal IOL) . This lens has multiple zones of varying converging powers on its front surface and is made of silicone.. The distant objects, mid-range and near objects, all are in focus and thus there is virtually no need of any glasses. Multifocal IOLs offer the advantage of clarity in the entire viewing range but they have poor comtrast and color saturation, some patients may also experience haloes and glare. However, these are only minor problems which the person gets easily used to. These IOLs are definitely an option to get rid of glasses after cataract surgery.
Have realistic expectations
To conclude, the surgeon, the surgical technique and the quality of the IOL are not the only factors that decide the result of cataract surgery; but also the condition of the eye otherwise, the cornea, the retina and the presence of systemic diseases like diabetes, hypertension, asthma, infections, etc. However experienced hands with the best of the equipments, the surgical risk is minimal. Though the overall results are excellent with restoration of good vision, yet it is not possible to duplicate nature’s gift of vision.