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. Development of Cataract 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.
The cataract occurs as a result of the natural aging process of lens fibres which become opaque over a period of time.
This occurs as a result of excess intake of oral steroid or putting steroid drops in the eye.
Here, cataract develops as a result of some other primary ocular disease such as chronic eye inflammation or glaucoma.
The earliest surgery treatment was started in India, by Maharshi Sushruta. It was known as ‘couching’, where the cataractous lens was dislocated backward into the bottom of the eye and out of visual 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 phacoemulsification, which has made couching obsolete.
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.
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: for complete retinal evaluation. Dense cataract will prevent retinal evaluation and such cases need B-scan for 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.
Optical biometry: this is an advanced non contact method to measure IOL power. It is patient friendly and highly precise
Phacoemulsification is latest technology in Cataract surgery. It is a micro-incisional stitch less operation where cataract is emulsified by ultra sound energy, liquefied & sucked through the phacoemulsifier probe. A foldable intra- ocular lens is then implanted in the eye permanently.
Vision restoration is possible in a short period of time & is least traumatic with early rehabilitation & recuperation.
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.
An intraocular lens (IOL) implant is a synthetic, artificial lens placed inside the eye that replaces the natural lens which is surgically removed usually as a part of cataract surgery.
Monofocal intraocular lens can be used to give clear point focus either at a distance or close up, but one can choose only one focal point.
Multifocal IOLs are popular as they allow correction of vision for both far & near distance.
Trifocal IOLs provides excellent vision not only for near and far, but also for intermediate distances, especially for people who have routine usage of computers.
Gradual diffractive steps on the IOL implant that create a smooth transition between focal points. The IOL bends incoming light to the multiple focal points to increase vision in differing light situations.
Crystalens and Trulign Toric currently are the only US-FDA -approved intraocular lenses (IOLs) that use a method called accommodation, enabling sharper vision at multiple distances for people who have undergone cataract surgery.
An accommodating IOL shifts position with the action of eye muscles and movement to improve eyesight.
This is a monofocal IOL with astigmatism correction built into the lens.
IOLs include filters to protect the eye’s retina from exposure to UV and other potentially damaging light radiation. The eye doctor selects the filters that will provide appropriate protection for the patient’s specific needs.
Other important cataract lens replacement considerations