Medical Questions & Answers » poor eyesight

Eyesight : Spectacles

medicalquestions — Thu, 19 Jun 2008 06:00:08 +0000

Alternatives to spectacles: There are four main options available to overcome the disadvantages of spectacles:
Contact Lenses
These are small polymer lenses, which are placed directly over the cornea. They are of two main types — soft and semi soft. Soft contact lenses are pliable and therefore very comfortable, but require utmost meticulous care and maintenance. Infections and allergy (GPC : giant papillary conjunctivitis) are the likely complications. Semi soft lenses (or Rigid Gas Permeable) are rigid and thus, initially, slightly uncomfortable to wear, but they do not require too much care. Complications like infection and allergy are uncommon with these lenses. However, in the Indian context infection, GPC, mishandling, dust and pollution associated conjunctivitis continue to be major causes of contact lens intolerance. Patient compliance is generally not satisfactory relating to the lens care and maintenance schedules.
• High degree of astigmatism cannot be corrected by contact lenses.
• Extended wear lenses are not suitable for Indian conditions.
• Hard lenses are obsolete and should not be used as they prevent oxygen supply to the cornea.
Refractive Kartotomy (RK)?
This is an operation where 4 to 8 (rarely 16) incisions are made on the cornea using a diamond knife. This results in flattening of the complications caused by RK.
Excimer LASER (PRK) technique
Using a computer controlled LASER (mostly Argon Fluoride 193 nm) the surface of the cornea can be reshaped imparting a predetermined curvature. This leads to correction of both myopia and hypermetropia, and also moderate amount of astigmatism, the procedure is short and simple and being computer controlled is highly accurate. The patients suitable for PRK are the ones above 18 years of age, with refractive error between 1 to 6 D and whose error has been stable for the last 1 year. There should not be any other complicating factor or disease in the eye. PRK, although a little expensive, is relatively safe in comparison to RK. The complications are postoperative pain (due to removal of epithelium during surgery), prolonged healing time and need to use steroids, slight corneal haze and late regression of the effect seen in some patients. It is not useful for high refractive errors and high astigmatism.
LASIK is an acronym for Laser Assisted In-situ Keratomileusis.
It combines all the advantages of the above procedures and virtually eliminates all their disadvantages. In LASIK an ultra-thin flap/ layer of cornea is raised using an automated cutting device called the microkeratome, and then Excimer laser is delivered to reshape the corneal stroma (inner layer of cornea) into desired curvature. The flap is repositioned back where it self seals without any stitches.

Cataract Operation

medicalquestions — Sun, 01 Jun 2008 06:00:32 +0000

Question: My GP said that I have a cataract and It will need an operation. Is this the best treatment for a cataract?
Behind the pupil in your eye is the lens. This is transparent and able to change its shape with the aid of tiny muscles attached to its edge. The change in shape enables it to focus on objects near and far.
A cataract is the clouding over of this lens. Once the vision has deteriorated sufficiently to cause significant sight impairment in both eyes, the worst eye will be operated upon, because this is the only way of treating a cataract. There are no medications or drops that will help. The operation is technically difficult, but can be completed in half an hour and is often done under local anesthetic. The cloudy lens is removed, and a new clear plastic lens is inserted. This new lens is not mobile, and cannot change shape, thus spectacles are normally required for close work, and sometimes distant vision as well.

Question: What is the best time to have a cataract operation? When it is only slightly annoying, or should I wait until later?
A cataract is the slow clouding of the lens in the eye, until it becomes like frosted glass, and impossible to see through.
There is no urgency about having a cataract operation until your sight has deteriorated to the point where glasses are unable to compensate for the clouding of the lens. Usually one eye deteriorates faster than the other, and when reading, driving or other skills become difficult, the worst eye will be operated upon. Only very rarely are both eyes done at once.
Once the bad eye has recovered, the other eye will be treated, and most patients find a dramatic improvement in their sight. One of the most common comments by patients after a cataract operation is that they find colors far brighter and more vibrant. The slow progression of the cataract over many years has had the same effect as slowly turning down the color control on a television to give a very washed-out effect.

Pterygium in the eyes

medicalquestions — Sun, 01 Jun 2008 06:00:22 +0000

Question: I would appreciate your opinion on the cause of a pterygium in the eyes. Some say it is glare, others sand or other foreign matter in the eyes. How is this condition caused, and how do you prevent it?
A pterygium is a fleshy overgrowth of the white part of the eye (cornea) that grows across the colored part of the eye (iris). They develop very slowly over many years, but once they are half way across the iris, they should be removed in a simple operation to avoid growth across the pupil and blindness.
Pterygium are very common in Australia, but more so in the north than the south, as they are caused by recurrent mild sunburn to the cornea. The irritated tissue overgrows, and spreads across the eye. Farmers, sailors, drivers, outdoor workers and sports people are most prone to pterygium as glare and sun exposure are the prime cause. The problem can be prevented by wearing good quality (polarized) sun glasses.
A pterygium may become irritated, red and itchy at times. Simple drops available from chemists will ease this problem. Once present they will remain until removed surgically. There are no drops that will make them go away.

Question: My mother is having a vitrectomy. What sort of operation is this?
The eye contains a clear jelly-like substance called the vitreous. If this becomes discolored, the vision in that eye will be remarkably reduced, possibly to the point of blindness.
The most common cause of discoloration of the vitreous is bleeding into the eyeball. This can occur in high blood pressure, diabetes and injury. In the last few years, a very delicate operation has been devised in which the blood-stained vitreous can be removed from the eye and a new artificial substance substituted, allowing normal vision again. It is performed under a general anaesthetic by an ophthalmologist (eye doctor) who has had specialist training in this procedure.

Squint in eyes

medicalquestions — Sat, 31 May 2008 06:01:40 +0000

Question: The doctor is concerned about my grand-daughter’s squint. What is a squint, and is it serious?
A squint (or strabismus, to give it its correct medical name), occurs when the two eyes do not align equally when looking at a distant object. One eye appears to be looking in one direction, while the other is looking in a different direction. This is quite normal when looking at something very close, as both eyes turn in to look at it.
If a child does have a significant squint, the brain will gradually suppress the sight in one eye, to avoid double vision. The affected eye may never learn to see again, resulting in the child becoming blind in that eye. The correction of a squint at an early age is therefore vital. Treatment usually involves prescribing special spectacles to correct the problem. If the squint is more severe, the good eye will be covered for a period every day, as well as using the glasses. This strengthens the vision in the poor eye and prevents blindness in that eye. In marked degrees of squint, it is necessary to operate on the tiny muscles that control eye movement to shorten those that are not pulling the eye around far enough.

Black flashes in eyes

medicalquestions — Sat, 31 May 2008 06:00:40 +0000

Question: I get flashes of black or clear spots or shapes in my eyes. My vision is still perfect. Any suggestions?
I have several suggestions as to the cause, but they will all end the same way— you must see a doctor!
The most likely cause is that you have a floater in your eye. This is a clump of cells floating in the fluid inside the eye. They can be quite annoying, and can be destroyed by laser treatment. The problem is what has caused the floater? The cells may have broken away for no serious reason, but it is possible that they are the first sign of significant eye problems. For this reason floaters must always be checked by an ophthalmologist (eye specialist).
Spots in your vision may also be due to migraines (and these are not always accompanied by a headache), a damaged retina (the light-sensitive layer of cells at the back of the eyeball), a cataract (cloudiness or damage to the lens in the eye), a deteriorating blood supply to the eye (for example after a stroke) or due to a tumor in or around the eye or the brain.
It is because there are so many possible nasty causes that it is essential to have an accurate diagnosis.

Question: Can glare damage your eyes?
Yes. Glare will cause chronic inflammation to the narrow segment of the white of the eyes that is exposed to the reflected sun’s rays when squinting. Over a period of several years this can lead to the build-up of scar and fat tissue in this area. This is known as a pinguecula. They cause no harm to the eye, but are unsightly and may become inflamed and itchy. Cataracts may also be aggravated by glare, including the glare reflected from water onto the eyes.
The problem is prevented by wearing high-quality sun glasses.

Treatment of Glaucoma

medicalquestions — Fri, 30 May 2008 09:45:48 +0000

Question: My mother has been diagnosed as having mild glaucoma, but all the doctor has done is give her some eye drops. How is glaucoma treated?
Your sight is one of your most valued possessions. Any disease that can reduce your vision, or worse still, make you blind, is of great concern. One such disease is glaucoma.
Glaucoma is an increase in the pressure of the fluid inside the eye. If this pressure becomes too high, the eye can be permanently damaged. It is diagnosed by measuring the pressure inside the eyeball. There are two methods of measuring the eyeball pressure. In the older method, special drops to numb the eye are used, and then an instrument is rested on the eye for a few seconds. A more sophisticated method is to use a machine that puffs air onto the eye for a fraction of a second and measures the amount of air pressure reflected from the eye. Both can give very accurate measurements of the eye pressure. Looking at the outside of the eye at different angles, and examining the back of the eyeball with a magnifying instrument also help make the diagnosis. There are more than 20 different types of glaucoma, with different causes and therefore different treatments. It is a complex area, that once suspected or diagnosed, is best dealt with by an ophthalmologist (specialist eye doctor).
Treatment involves the use of one or more eye drops on a regular basis, every day, usually for the rest of the patient’s life. Some types of glaucoma may also require the taking of tablets. Occasionally the disease settles spontaneously in old age. Glaucoma cannot be prevented, but it can be controlled successfully in nearly all patients, and sometimes it can be cured by surgery. The surgery increases the rate of drainage of fluid from the eye, and may involve the use of lasers to burn microscopic drain holes in the corner of the eye. With modern treatment techniques, the outcome for patients with glaucoma is normally very good, but continued follow-up by a doctor is essential.

Pterygium in the eyes

medicalquestions — Fri, 02 May 2008 06:00:46 +0000

Question: I would appreciate your opinion on the cause of a pterygium in the eyes. Some say it is glare, others sand or other foreign matter in the eyes. How is this condition caused, and how do you prevent it?
A pterygium is a fleshy overgrowth of the white part of the eye (cornea) that grows across the colored part of the eye (iris). They develop very slowly over many years, but once they are half way across the iris, they should be removed in a simple operation to avoid growth across the pupil and blindness. Pterygium are very common in Australia, but more so in the north than the south, as they are caused by recurrent mild sunburn to the cornea. The irritated tissue overgrows, and spreads across the eye.
Farmers, sailors, drivers, outdoor workers and sports people are most prone to pterygium as glare and sun exposure are the prime cause. The problem can be prevented by wearing good quality (polarized) sun glasses. A pterygium may become irritated, red and itchy at times. Simple drops available from chemists will ease this problem. Once present they will remain until removed surgically. There are no drops that will make them go away.

Question: My mother is having a vitrectomy. What sort of operation is this?
The eye contains a clear jelly-like substance called the vitreous. If this becomes discolored, the vision in that eye will be remarkably reduced, possibly to the point of blindness.
The most common cause of discoloration of the vitreous is bleeding into the eyeball. This can occur in high blood pressure, diabetes and injury. In the last few years, a very delicate operation has been devised in which the blood-stained vitreous can be removed from the eye and a new artificial substance substituted, allowing normal vision again. It is performed under a general anesthetic by an ophthalmologist (eye doctor) who has had specialist training in this procedure.