CATARACT
Cataract is that condition of the eye where the clear natural lens become opaque and affects the vision. It is  caused by various factors like age, heredity, ultraviolet light exposure, injury, diabetes and medications like steroids.
There is no medical treatment for cataract. Surgery is the only option.
Symptoms Early stage: Blurring of vision, seeing multiple images and glare
Advanced stage: Cataract can cause complications like inflammation and increased pressure in the eye causing pain and redness
Timing of Surgery:
1. Lifestyle: Timing of surgery can be decided by patient based on their requirement. In a patient leading an active life and driving in the night, even a 5% central cataract may affect his quality of life, whereas a patient leading a retired sedentary life may not opt for surgery even if a significant cataract is present.
2. Duration of cataract: It is advisable not to delay the cataract surgery because long standing cataract leads to hardening of the central portion of lens which may become difficult to break with ultrasound. Hard pieces can hit the cornea and cause significant complications during cataract surgery.
Procedure:
    
Phacoemulsification: This is the latest procedure, where a wound of about 2 mm is made & with an ultrasonic needle, the cataract is broken into pieces and aspirated. An IOL of suitable power is then implanted in the same position of the natural lens.
IOL (Intraocular lens): There has been considerable improvement in IOL technology. There are two basic types-non foldable and foldable. Non foldable IOLs are hard, made of glass like material and cannot be folded. With these lenses, after removing the cataract, the wound is extended & a lens of 6 mm diameter is implanted. The trend is to implant a foldable IOL which are made of soft material which can be folded. These are implanted with the help of special injectors. Foldable lenses are of different materials like Silicone, hydrophilic Acrylic and hydrophobic Acrylic
Acrylic IOL: Acrylic lenses with square edges have been highlighted off late to reduce the problem of capsular opacification which can happen several years after cataract surgery. Capsular opacification affecting the vision is known to occur with old age, diabetes and certain types of cataract.
Aspheric IOL: Corrects the overall imperfections (aberrations) in the eye resulting in vision following surgery like a young adult enjoying good quality of vision in different lighting conditions.
Multifocal IOL: Zones of different powers covering different distances are available for patients who need decreased dependence from spectacles. These are high quality IOLs giving good vision, both for distance and near, without spectacles. Patient needs to undergo surgery in the other eye soon, so that the brain gets adapted. One of the important challenges is to reduce the pre-existing corneal power (astigmatism), by making cuts on the cornea so that the patient can enjoy good vision at different distances without spectacles.
Accomodative IOL’s : These IOL’s are meant to provide good near vision in addition to distance vision without the zones of different power as in multifocal IOL’s
Investigations needed before surgery: Blood sugar, Blood pressure, Cardiac evaluation, ‘A’ scan and Keratometry test (to find IOL power to be implanted).
LASIK
LASIK (Laser Assisted In Situ Keratomileusis) is an advanced laser vision correction technique and an attractive option to remove spectacles where the curvature of the cornea is altered using laser.
ALL YOU NEED TO KNOW ABOUT LASIK TREATMENT
- Patient should be at least 18 years of age
- The glasses power should be stable for at least one year
- LASIK is done till about –10 Ds of myopia(near sightedness) and +5Ds of hyperopia(far sightedness)
- The routine tests which are done before surgery are refraction (glasses checkup), intraocular pressure, retinal examination, corneal thickness, corneal curvature and measurement of minute aberrations in the eye called aberrometry.
Patient needs to discontinue contact lens before corneal thickness and curvature evaluation. Soft lenses needs to be discontinued for about a week and semi-soft lenses for 3 weeks. The normal cornea thickness is about 520 to 530 microns. Contact lens wear for many years makes the cornea thinner by 10 microns.
Patients with low power like -2 or -3 diopters have higher chance of getting fully corrected than those with higher powers. In higher errors, since we ablate deeper, healing is more and the patient’s end correction can be in between 0 to -0.5 diopters. If healing is excessive and if the patient lands up more than -1 diopters, we can fine tune the correction by application of additional laser.
While creating the flap, the nerves are affected and dryness of the eyes can be a problem. Patients are prescribed artificial tears for about 2 to 3 months till the nerves regenerate.
In Photorefractive keratectomy (PRK) technique, the laser is applied on the surface of the eye. The surface heals by 3-4 days leading to recovery of vision of about 60- 70% by 3-4 days and vision is clear by 7 -10 days. To avoid disturbing the surface, in LASIK treatment, a thin flap of cornea is created with a microkeratome, the flap is pulled back and then laser is applied.
The decision to do LASIK or PRK is based on the corneal thickness and the amount of refractive error. If thickness is between 460 to 500 microns, PRK is recommended for refractive error upto -6D. If the thickness is less than 460 microns, then patient is offered phakic IOL implantation. A safe model called STAAR implantable contact lens is available. This is a plate like lens which will be positioned behind the Iris and floats in front of natural lens. This is usually recommended for very high refractive errors and in patients with very low corneal thickness, where LASIK and PRK would not give very good visual results.
After LASIK laser vision correction, vision is slightly blurred on the day of surgery. The vision improves overnight. On the day of surgery, it is better not to watch TV or get exposed to excessive sunlight. The patient is suggested to sleep as much as possible for comfort. Antibiotic and steroid drops are prescribed for 5 days and artificial tear drops for 3-6 months. May be after a couple of days, the patient can resume his routine activities. Goggles during day time and eye shield at night are suggested for few days. Patients are advised not to splash water into the eyes for about one week to 10 days.
After PRK, the surface layer of cornea called the epithelium peels off. To prevent the lids touching the bare cornea, a zero powered bandage contact lens is applied for comfort. The lens is usually removed after 3 days following healing of epithelial defect.
STANDARD TREATMENT: In this procedure, only the refractive error is corrected by changing the shape of cornea. One of the issue of myopic LASIK procedure is the induced imperfections or aberrations as the central cornea is flattened. In a standard procedure, the aberrations are increased. Huge amount of aberrations after treatment as it happens in a patient with pre-existing high aberrations and very high amount of refractive error correction can affect the contrast sensitivity. Patients may complain of objects appearing dimmer than what they used to have with glasses or contact lenses. Fortunately, Indian patients have darker Iris and smaller pupils and many of these symptoms complained by Caucasians or white race individuals because of light Iris color and large pupils are not complained by our patients.
CUSTOMISED TREATMENT: Here, in addition to power the overall aberrations in the eye are also taken care off. The aberrations are measured with an instrument called aberrometer. The data from the aberrometer is transferred to the laser machine. The laser machine in addition to removing the power, also take care of these minute aberrations resulting is better quality of vision even in dim light. Compared to standard treatment, customized procedure is advanced as not only the power is removed, but also the pre-existing aberrations are corrected and induction of new aberrations is minimized.
LASIK and PRK for hyperopia or far-sightedness: It is easy to flatten the cornea than to steepen it, as is done in hyperopia or farsightedness. These procedures yield good results till about +5 D of hyperopia.
Bladeless LASIK : Now recently femto second laser is becoming popular to make the flop so that no blade is used making the entive procedure bladeless with femto second laser to surgeoncan make &precise flop of required thickness, better configuration of flop & avoid flop related complications like button holes & free caps associated with blade. |
