The retina is the thin inner lining of the eyeball. It acts like the film in a camera to "make the picture". Tiny light-sensitive cells pick up the signals of the world around us and transmit them via the optic nerve to the brain. Because of the way the light falls, the image on the retina is upside-down. Fortunately for us, however, the brain quickly re-invents the picture or else we would all be walking on our hands! Doing all the hard and vitally important work that it does, the retina needs a lot of energy from the body. Consequently it has its own little system of blood vessels which have no connections to other vessels. This means that another part of the body cannot steal the retina's blood but conversely, when a small retinal artery is blocked, severe damage to the retina occurs as there is no blood to steal from anywhere else! When one of the small vessels or their branches becomes blocked sudden loss of vision can occur. No time should be lost in seeing your ophthalmologist because, in the case of a small artery blockage, immediate treatment can sometimes be successful. Your ophthalmologist will probably also want you to undergo some systemic investigations as diseases such as high blood pressure, diabetes and others may be implicated. 

Another important fact is that the little light-sensitive cells, which are divided into those that work in the dark (called rods) and those that work in the light (called cones) are constantly breaking down and re-building. When things go wrong with this system retinal degeneration occurs. The cones are mostly concentrated in the central or "bull's eye" area (called the macula) which we use for clear vision and reading while the rods, which are more concentrated in the periphery, are needed for night vision. 

An important problem affecting the macula occurs as the eye (and the patient!) ages. Slow deterioration in this area makes reading and fine close work difficult. Tiny blood vessels may develop and cause distortion of vision or even bleeding. Your ophthalmologist may recommend special photographs or laser treatment to the back of your eye. It is important to remember that the treatment is aimed at preventing further deterioration only. Unfortunately, the opposite eye may also become involved over a period of years. We call this condition Age Related Macular Degeneration. Considerable research is being done and surgical techniques being developed which may occasionally be helpful. 

Inherited disorders may cause macular deterioration in much younger patients but one of the commoner degeneration's is Retinitis Pigmentosa which, especially in the early stages, affects the rods and causes night blindness and "tunnel vision". Genetic research has helped us to identify some of the faulty genes and the race is on to find a cure. 

Another serious condition which may affect the retina is retinal detachment. This means that the retina has come loose from the back of the eye much like wallpaper peeling of a wall! This usually happens when a tear or hole develops in the retina allowing fluid from inside the eye to seep under the retina. The first thing that the patient may notice is flashes of light or a shower of little dots called "floaters". It is important to see your ophthalmologist if you notice these symptoms, especially if you are short sighted or anyone else in your family has had a retinal detachment. The next thing that happens is that a "curtain" or shadow comes over the vision. When surgery is offered this may be a procedure involving mainly the outside of the eye or may be internal with the injection of a gas bubble or in very severe cases a special oil called silicone oil. The most important thing in the successful treatment of retinal disease is to present as early as possible to your ophthalmologist if you notice any of the symptoms we have mentioned especially if you have a family history of retinal disorders.

Whenever the light focusing system in front of the eye (mainly the cornea, also the lens) produces an image either in front of (myopic or shortsighted) or behind (hyperopic or longsighted) the retina, vision is blurred and some additional focusing system such as spectacles or contact lenses are necessary to shift the focus onto the retina.

The further the image is from the retina, the thicker the spectacles (or contact lenses) must be to achieve this focus on the retina and therefore clear vision.

I EXCIMER LASER SURGERY

We cannot shorten or lengthen the eyeball, but we can now alter the shape of the front of the cornea sufficiently in most cases to shift the focus (image) from it's abnormal position to the retina, and therefore restore good vision without glasses. There is obviously some risk associated with this, so however small this risk might be, surgical approach is not considered if patients are comfortable with their glasses or their contact lenses.

The altered shape of the front of the cornea can be achieved via Laser (Excimer) Refractive Surgery as follows:

I A Laser in-situ keratomileusis

Laser in-situ keratomileusis, or LASIK, is considered safe and effective for patients with low to high myopia (up to +-10 diopter of shortsightedness), with or without astigmatism, and low to moderate hyperopia (up to +- 3 diopter of farsightedness). The ophthalmologist uses an automated microkeratome to cut a thin, hinged layer in the cornea, called a flap. The flap is then laid back and the surgeon uses an excimer laser beam to flatten the underlying cornea by vaporising a thin layer of tissue. The flap is gently put back in place. The cornea heals without any stitches. 

Local anaesthetic drops are used (no injections) to render the eye insensitive. Mild sedation is also usually advisable. Because of this you should not drive your car for at least 12 hours after the operation.

NB. Stop cosmetics at least 5 days before Laser Surgery, soft contact lenses at least 1 week before surgery and hard contact lenses 2 weeks before surgery - confirm these times with your Ophthalmologist as some patients need longer.

Possible Complications:

An imperfect flap at operation. If this happens, no laser is applied, the flap is replaced - and reoperation performed 1 - 3 months later.

Epithelial defects at operation - these heal within 48 hours and will be covered with a bandage contact lens.

Infection - extremely rare, statistics show this to be about 1:50 000 operations.

Corneal "haze" or light scarring - about 3%. This would cause mistiness of vision, halo's around lights (especially at night), and may need lifting of the "flap" to remove unwanted material.

Regression. Some patients tend to revert partially to their previous refraction. Excimer / Lasik "top up" may be done on these patients.

Haloes around lights, especially when driving at night - this gets better after 6 months but never completely disappears. 

With all types of surgery there is a possibility of other complications including those due to anaesthetic agents, drug reactions etc, and factors which may involve other parts of the body. Since it is impossible to state every complication which may occur as a result of any surgery, this list is incomplete.

Frequently asked questions:

Who can have this ?

Not all people with refractive errors are good candidates for refractive surgery. Your ophthalmologist is the best source of information on refractive procedures and the options you have to correct your particular refractive error. Patients with thicker spectacles benefit most from this procedure.

Laser Surgery aims to eliminate (or substantially reduce) this handicap. You may need thin glasses afterwards for very sharp vision, but should have about an 80% chance of going without spectacles 80% of the time - depending on your refractive error.

How can I find out if I am a good candidate for Excimer Laser ?

You need to be screened and assessed by your local Ophthalmologist. Your eye surgeon will be able to give you a good idea whether you are a possible candidate. The procedure, as well as advantages and disadvantages will be discussed with you. You will need to remove soft contact lenses five days before this assessment, and hard contact lenses at least two weeks before the assessment.

What age do I have to be ?

Minimum of 18 years, with a stable refraction for at least one year.

There is no maximum age, but short sighted patients over 45 years old should remember that they are unlikely to be able to read without glasses after this procedure.

Is the treatment permanent ?

World wide experience shows that patients experience longterm benefits. However, laser surgery does not prevent the natural changes that occur with ageing, and this may include gradually increasing shortsightedness or longsightedness.

Can I wear contact lenses after this surgery ?

Yes - most people will be able to wear soft contact lenses if necessary. Sometimes, a hard contact lens might be necessary.

Can they have both eyes operated on at the same time ?

Most possibly, but only after thorough discussion with your eye surgeon. 

How long do I need to be off work ?

About two days after surgery.

Is there any post-operative follow up ?

Yes - you will have post-operative checks until your vision is stable. 

Do I need to use eye drops after the surgery ?

Yes, most patients need drops for about one week.

When will I be able to drive ?

You will probably be able to drive after a few days. However, driving at night may be affected by glare for a while.

How long does the procedure take ?

About 10 minutes per eye. 

Is the procedure painful ?

No - anaesthetic drops numb all pain. You will be aware of the eye surgeon working on your eye though. 

Is there pain afterwards ?

Normally there is only a slight scratchy feeling for a day or two.

Will I be able to drive myself home after the surgery ?

No, you will have eye shields covering both eyes, and you will need someone to drive you home. 

I B PHOTOREFRACTIVE KERATECTOMY OR (PRK)

With this method the laser beam is applied directly to the surface of the cornea, after the thin superficial layer of cells has been wiped off. After the laser resculpturing of the cornea is done, it takes a day or two to heal and it can be uncomfortable during this period. The healing process sometimes leads to regression (some refractive error returns) or to scarring. 

II PHAKIC INTRA-OCULAR LENSES

In cases of severe refractive errors exceeding the safety limits for Excimer laser surgery, you might be advised by your eye surgeon to have a phakic lens implanted. This is a special "contact lens" designed for permanent implanting into the eye, after which "fine tuning" of the refractive error will be done with the Excimer laser. The advantages and disadvantages of this procedure will be discussed with you. This method is only advised in patients under 40 years of age, who do not require reading glasses yet. 

Your eyes will be assessed thoroughly and the phakic intra-ocular contact lens will be manufactured to fit your eye specifically. According to the type of lens chosen, it can either be implanted in front of or behind the iris. Excimer laser surgery can be performed about a week after this surgery.

Possible Complications:

1 Cataract formation (about 30%)

2 Endophthalmitis (about 0.01%)

3 Pressure increase (about 10%)

Are you always searching for your reading glasses? Have you ever wished that there were a solution to this problem? When you are in front of the television your glasses are either in the bedroom, kitchen, car or even at the office. With the development of technology there is an operation available which could eliminate this problem and make the "old" eye as good as new. 

Reading problems will start to occur at the age of about 40 years and affects just about everybody after 45. When the eyes are focusing close up, the lens changes its shape. The diameter increases and light rays are focused on the retina. As we get older the lens grows and when the space are too limited to adjust its shape, reading problems start to occur. 

Modern technology has proved that by increasing the diameter of the eye it is possible to eliminate problems with reading. This enables the lens to change shape and focus again close up for reading. 

Increasing the diameter is achieved by inserting 4 plastic arches into the white of the eye(sclera). These arches have a very specific design and are being produced, under license, in America. 

The recovery process depends on the age of the patient. Persons under the age of 50 will recover quicker than those over 50. It can take up to six months and requires a lot of exercise. This can be compared to a broken arm or leg. When the plaster of paris is removed the bone is tin and the muscles are weak. The muscles need to regain their strength as soon as there are sufficient space available for the lens to change its shape while reading. 

Who qualifies for this operation?

Patients over the age of 40.

No underlying refraction errors. Other refractive procedures need to be treated (e.g. Lasik operation) before the reading problems can be addressed. Patients with no underlying eye diseases. Some systematic illnesses may be a relative contra-indications (e.g. Diabetes) 

How is the operation performed?

The implants are done under general anaesthetics and the patient goes home that same day. You will have to come for a one-day, a week, a month and a three-month follow-up after the operation. Only one eye is done at a time. In some cases it will only be necessary to do one eye. Some patients will be able to function effectively if the dominant eye is done first. 

What are the dangers involved?

As with any other operation there is always the risk of infection. To prevent this the operation is performed under sterile conditions in theatre. It is possible that the arches may move which will reduce the effectiveness of the procedure. This can be corrected by repositioning the arches under anaesthetic. There are even a small percentage of cases where the eye has rejected the arches. This seldom happens, but is possible. 

What can I expect immediately after the operation?

• For the first week the eye will be red and scratchy.
• Vision may fluctuate, especially for reading.
• Headaches may follow due to the eyedrops prescribed.
• Nausea due to the stretching of the eye. The body must adapt to the new shape.

Contact your local ophthalmologist for more information.

It is positioned just in front of the iris, which is the structure that gives each person's eye its individual color. Light rays pass through the clear cornea as they enter the eye. Should the cornea for any reason become cloudy, the person's vision will be permanently reduced.

There are many reasons for the cornea to become cloudy : 

Young people are often born with abnormalities of the cornea. In a condition known as keratoconus, the cornea develops an abnormal curvature that makes normal vision impossible. Childhood infections such as measles can also cloud the cornea, often causing permanent blindness throughout the person's life. 

In later years infection or trauma to the eye, are the main causes for the cornea to become opacified and this can once again reduce the vision making it difficult for the person to work and earn a living. 

In the older sections of our population, degenerative diseases, often caused by excessive exposure to the harsh sunlight of South Africa, can cause the cornea to become dull with a resultant loss in vision. Old people then find it increasingly difficult to function. 

The dull opacified cornea can however be transplanted with a new cornea, thus restoring the vision of the patient, whether he be a young child, an adult or an old person. The operation is performed by highly trained ophthalmic surgeons using the latest micro surgical techniques. Hospitalization is however often no longer than a day or two. The success of such grafts are more than all other forms of organ transplantation; a more than 90% chance of the new cornea retaining its clarity. 

There is however in South Africa a tremendous shortage of corneal donors. It has been estimated that there are more than 20 000 blind South Africans whose sight could be restores with a corneal graft. It is thus essential that the general public become more aware of corneal grafting and agree to donate their corneas or the corneas of their diseased relatives for grafting. Corneas from donors of all ages are used. Usually only the cornea is removed from the deceased and donating a cornea is thus not a disfiguring procedure. 

It is thus essential that more people agree to donate their corneas and, should a person have a "Living Will" or a Medic-Alert Identification tag, this intention should be included. When obtaining a new driver's license, the person's intention to donate their corneas can be entered onto the driver's license.

Its development is not related to injury or inflammation. 90% of pterygia are located nasally. Both eyes are frequently involved but often only one.

The pterygium can advance to involve the visual axis causing marked loss of visual acuity. 

The pterygium can be distinguished from a pingueculum, which is a small-elevated yellowish mass, which can become inflamed. The pterygium grows in the interpalpebral fissure (that is the exposed part of the eye) as an elevated fleshy mass of the conjunctiva.

Symptoms

Burning, irritation, tearing and a foreign body sensation may accompany the growth of a pterygium onto a cornea. Astigmatism may be induced and may lead to decreased vision. As the apex of the pterygium approaches the visual axis, glare and reduced contrast sensitivity appear.

In severe cases symblepharon formation (adhesions) may limit ocular motility and result in diplopia, which is double vision.

For poorly understood reasons the pterygium growth may stop at any stage. It may remain so for the rest of the patient's life or at a later date again start growing.

Etiology and Epidemiology

There is a worldwide distribution of pterygium but it is more common in warm, dry climates. Studies have shown a strong relationship between ultraviolet radiation and the formation of pterygia.

A study in Australia identified a number of risk factors:

• Living in the tropics
• Working in a sandy outdoor environment
• Not wearing sunglasses
• Not wearing a hat

Local drying of the conjunctiva and tearfilm abnormalities may also be contributing factors.

The highest incidents occur between the ages of 20-49 and rarely occur under the age of 15.

Treatment

The decision to remove a pterygium is dependant on the patient's symptoms and the interest in cosmetic improvement. Recurrences may be more frequent in young adults. Virtually all post-operative recurrences occur within the first year after surgery and often within 6-8 weeks. With recurrence there is a higher incidents of growth into the visual axis and of symblepharon formation. 

Medical Treatment

Eye drops such as preservative free lubricants, vasoconstrictors and mild cortico steroids can relive the symptoms. Some believe ultraviolet-blocking spectacles can prevent progression. 

Surgical

The pterygium is removed surgically and the method depends on the surgeon doing the operation.

1. The pterygium is avulsed.
2. The pterygium is excised and the underlined sclera is left exposed, that is bare sclera.
3. Transplantation of the head of the pterygium away from the cornea beneath the superior edge of the adjacent normal conjunctiva.
4. Keratectomy, that is, a superficial layer of the cornea is removed with the removal of the pterygium to the cornea. The pterygium may then be removed and the sclera left bare as above or the head of the pterygium can be transplanted.

Adjunctive Therapy

A number of therapies are used to decrease the risk of recurrence after surgical removal of the pterygium. The treatment used again depends on the surgeon's preference. Each has attractive features but none is without drawbacks that are side effects. 

The following may be used:

1. Steroid drops.
2. Thiotepa, a radiomimetic agent, which presumably obliterates proliferation of vascular, cells and is very rarely used today.
3. Mitomycen C is an antineoplastic-antibiotic agent, which inhibits the synthesis of proteins.
4. Beta-radiation. Strontium-90 applicators are used to radiate the site of the pterygium after surgical removal.

Future Prospects

The first report of a surgical treatment of a pterygium is more than 3000 years old. The management of pterygia and recurrent pterygia is improving yet many questions remained unanswered. Future studies may elucidate the cause of the pterygium as well as the cause of complications related to the adjunctive therapy after pterygium surgery and prevent recurrence.