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 Basic Eye AnatomyEYE BASICS The human eye is somewhat like a camera. It's a ball shaped organ about an inch in length and rests in a bony protective socket called the Orbit. The entire eye is wrapped in an outer white layer, "The white of the eye”, called the Sclera covered with a thin movable transparent film, the conjunctiva. When this conjuctiva gets infected it become “Pink” and we say that the person is suffering from, conjunctivitis. Right in front is the clear window of the eye called the CORNEA. It allows light into the eye. This is the structure that is replaced in “eye donation”. Contrary to popular belief the entire eye cannot be transplanted, its only the cornea which is transplanted to restore a patients vision. When Aishwarya appears in the advertisement and says donate your eyes, she actually means donate your corneas. Just behind the cornea we find a curtain with an opening called the IRIS. The iris is responsible for the color of the eye and in dark skinned, middle eastern Asians is brown in color due to the presence of pigment. In white people it is blue due to the absence of pigment. In days gone by people “claimed” to know the health of a person by examining the iris and called it IRIDOLOGY. Like other sciences such as reading the bumps on a persons head to determine their future it has waned in popularity! The black hole we see in this movable brown curtain is called the PUPIL. It acts like the aperture of a camera and lets more or less light into the eye by becoming wider or smaller in response to external light. When we see a cats eye at night we realize that the excellent night vision of a cat is because the pupil of a cat opens very wide. Just as the camera has a lens to focus light the human eye indeed has a similar lens. This is the structure which when it looses its clarity is called a cataract. Behind the human lens is a formed jelly called Vitreous, not unlike the jelly which sets in a jelly bowl, behind which is the most delicate part the retina. The Retina is the light sensitive layer of the eye and is made of 10 layers. It lis like the film in a camera and captures the image on it. In spite of having 10 layers its only 0.8 mm thick, like a sheet of tissue. More than one million of these retinal nerve fibers leave the eye together as the optic nerve which travels along the base of the brain and reaches the back part of the brain called the occipital cortex. Remember the eye is just a camera and a light and colour sensor like the sensor in the digital camera of today, it’s the brain that actually “sees”. |
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What
is a Cataract? A cataract is nothing but a Clouding of the Lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people by age 65. More than half of all Indians have either a cataract or have had cataract surgery. A cataract can occur in either or both eyes. It cannot spread from one eye to the other. |
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What are the symptoms of a Cataract? The most common symptoms of a Cataract are:
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| Cataract Cataract surgery was invented in India!! Circa 600 years BC the Indian sage Sushrut, in his textbook described cataract surgery with local anaesthesia in the days when the rest of the world were climbing trees and huddling in caves! He also used plastic surgery techniques including forehead flaps and described over 300 surgeries in all. The Arab doctor Shams Ud Deen, described Glaucoma hundreds of years ago and spoke of Cataract as white water in the eye or “mai abiyat” a term still used today in the middle east. The words Cataract Surgery, inspire anxiety and denial in people, mostly because they are ill informed about the disease and its treatment. If we are fortunate enough to live to a ripe old age, we will develop cataracts. For indeed the most common type of cataract is part of a natural process of ageing. A cataract is simply opacification or clouding of the human lens in the eye so that light is not focused properly on the Retina leading to a blurred image. |
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The most frequent symptoms of Cataract are:
Cataract can develop at any age. Newborns can have cataract due to infection in the womb commonly due to rubella. Young children can develop cataract due to metabolic imbalances and infections for eg. the inability to digest milk is sometimes associated with cataract. Any blow to the eye in play and even severe malnutrition can lead to cataract in childhood. The use of steroid containing skin creams for months, putting steroid anti allergy eye drops for a long period of time and exposure to sunlight can cause cataracts in the 20-40 year age group. Cataract is seen in glassblowers and in foundry workers due to infrared rays and so its advisable to have protective dark spectacles in these professions. Diabetes, other eye diseases, Glaucoma and even any eye surgery or retina detachment lead to Cataract. Anytime there is an internal eye disease, Cataract is the likely result! In old age the most common type of Cataract called Senile Cataract is seen. This is because the proteins in the human lens congeal and coagulate like the egg white in a frying pan leading to a whiteness. Finally, exposure to radiation for eg. Nuclear power plant technicians and people undergoing radiotherapy for cancer of the head and neck are likely to develop Cataract. |
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Prevention: Avoid blows to the eye in sports like squash and badminton by wearing protective spectacles (mandatory in the west) Make sure your diet has the necessary vitamins and minerals. Follow your gynaecologists advice at the time of conception and delivery and do appropriate blood tests as recommended by them. Sunlight exposure is a prominent cause ,so do not venture in the sun without sufficiently dark sunglasses. If you work in a steel mill or any area where a lot of red heat is present make sure you wear eye protection. Do not put steroid creams indiscriminately or use eye drops long after the doctor has stopped prescribing them. |
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Treatment of Cataract From time to time many people claim to reverse halt or treat cataract using medication and eyedrops which is a fallacy. The only treatment for cataract is to remove it. In the fifties and sixties intracapsular surgery was performed where the whole lens in its bag was removed after the eye was cut open by 180 degrees i.e. half the eye was cut open with a blade. The big disadvantage was that since there was no lens the vision was poor and very thick +10 number spectacles had to be worn continuously. Patients lay still for upto 2 months at a time till the wound healed. Naturally in the summer this was intolerable as bathing was banned for more than a month. Even today people refrain from cataract surgery in the summer as a hangover of the old days! The 1970’s saw the advent of implantable lenses. The eye was still cut open but by about 120 degrees now and fewer stitches were put. The risk of bleeding and poor vision and more complications were still there. Lenses in the eye are not a new invention. During world war two a young English Ophthalmologist (Sir) Harold Ridley noticed that small fragments of the cockpit canopy of the spitfire fighter in the eyes of pilots did not cause any reaction. Till 15 years ago all lenses were made of this Perspex material! Modern cataract surgery as we know it today uses different techniques to remove cataract out through between 0.7 mm to 3 mm. Laser energy or ultrasound energy or warn water jets are used to break up the cataract which is sucked out. The most modern of these techniques, about 2006 onwards uses warm water jets called AQUALASE to simply remove the lens gently by dissolving it. Also we can now go in through just 0.7 millimeter (as big as the tip of a ballpoint) and break up the cataract with ultrasound energy where the tip vibrates 40,000 times a second called 700 micron phaco. The lenses which are implanted in the eye today are very soft and are rolled up and injected into the eye through as small as 1 mm where they will open up. Naturally since the opening is so small it seals nearly instantly and the patient does not need sutures or a bandage.he can even resume work the next day with just protective glasses. Since the opening is so minute. The risk of bleeding is virtually absent and diabetics do not need time to heal etc as the amount of actual healing needed is miniscule. These lens materials today are acrylic and silicone and should comfortably outlast even a young patients lifespan as they are non reactive with the body. Lenses can be single focal i.e. the person does not need spectacles for distance or multifocal which means he or she is spectacle independent after surgery. However multifocal lenses are a compromise and the person may see rings of light at night and may still need a small number to read. Even so they have greatly gained in popularity despite their increased cost. For eg. the Restor multifocal lens retails for upwards of 1000 dollars for a single lens! In short, Cataract Surgery is no more the major adventure it was just 20 years ago and modern technology along with new techniques allow for a short hospital visit and nearly instant recovery |
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 A revolutionary Cataract removal system with unsurpassed performance offering for the first time in the world the New AquaLase® cataract liquefaction device, which is so innovative, that the cataract is removed with extreme safety, using only fluid ultra micro-pulses in milliseconds, gently and with unprecedented, virtual, total safety.Dramatically reduces the potential for complications. Represents a quantum leap over the older phaco techniques. The newest technology in cataract removal devices. !!!! MOST COMMON SURGERY NOW SAFER !!!!! New Cataract Surgical Device Designed to Reduce Complications More than 2.5 million people undergo cataract removal surgery in the US each year, and now researchers at Alcon Laboratories have recently devised a new technique that could make the most commonly performed surgery in the US a little safer.  There’s a new advancement in lens removal technology that may reduce the risk of thermal burns and other potential complications called the AquaLase® Liquefaction Device.Instead of using a metal probe, a doctor can now dissolve a patient’s clouded lens with pulses of warm naturally balanced solution to ‘wash away’ the lens layer-by-layer. First Alcon Infiniti Cataract Surgical System sold in India, Installed at our Institute. AquaLase® Liquefaction Device is part of the Infiniti™ Vision System, the world’s first tri-modal cataract removal surgical instrument. Alcon’s entirely new AquaLase® liquefaction device that generate fluid ultra micro-pulses in milliseconds, gently and with unprecedented, virtual, total safety safely break up and remove the natural lens material, dissolving the cataract. Increased flexibility and greater options provide surgeons with more control over the lens-removal procedure, which potentially offers the reduced risk of complications. It also represents the first departure from ultrasound phacoemulsification, which has been the industry standard for almost 25 years. |
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In the course of my practice and since this column has been well received over the last 2 months I have decided to answer some of the common questions patients and readers have posed to me.
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2009 © Copyright Dr. Cyres Mehta, Surgical Director & Chief - The International Eye Centre. All rights reserved. Website Designed by Rushi Web World |
