Astigmatism
In Astigmatism, an uneven curvature of the cornea blurs and distorts both distant and near objects. Normally, the cornea (front window of the eye) is round, with the same curvature along all axes/sides, rather like a football. The astigmatic cornea is shaped a little more like a rugby ball, curved more in one direction than in another. As a result, light rays from different meridians (axes) focus on separate areas of the retina, distorting the visual image.
Most people have very slight astigmatism, but a significant number require spectacle or contact lens correction to see clearly. Advances in laser techniques allow astigmatism to be corrected with
LASIK and LASEK. Wavefront guided techniques may also be beneficial
Keratoconus
Keratoconus is a condition which causes reduced vision due to a more extreme degree of astigmatism. Keratoconus is derived from the Greek words: kerato, meaning cornea, and konos, meaning cone. The cornea becomes distorted with a cone-shaped bulge.
Keratoconus affects approximately 1 in 2000 of the population, presenting mainly in the late teens or early 20s and remains the commonest indication for corneal transplantation in this age group.
Progression of the condition depends on many factors but includes the age at the time of the onset. The earlier the onset, the faster keratoconus progresses.
The condition almost always affects both eyes, with one eye usually more affected than the other.
What causes Keratoconus?
The precise cause of Keratoconus is unknown. We do however, know that there are several risk factors for its development. These include: hereditary factors, excessive eye rubbing, certain underlying disorders such as Downs Syndrome. Affected patients often suffer from allergic eye disease. Keratoconus treatments include the following:
1. Spectacles in the early stages of the disorder
2. Hard contact lenses when spectacles are no longer helpful
3. Corneal collagen cross linking (CXL) with Riboflavin which increases the strength of the cornea to prevent progression of the keratoconus
4. Intrastromal rings (Intacs)
5. Keraflex (Microwave Thermoplasty)
6. Corneal transplantation - deep anterior lamellar keratoplasty (DALK) or full thickness penetrating keratoplasty (PK) for more advanced stages.
What is Keraflex?
Keraflex is a new procedure which uses microwave energy carefully delivered to the mid-periphery of the cornea using a special machine. This procedure flattens the cone and helps to produce a more regular shape to the cornea. It is used in combination with collagen cross linking to achieve the best optical effect as well as the best degree of stability. http://www.youtube.com/watch?v=eAF8UciNLXE
Glaucoma
Glaucoma is a disorder in which the optic nerve head at the back of the eye is damaged, leading to progressive, irreversible loss of visual field and eyesight. It is often, associated with an abnormally high pressure of the fluid in the eye (a high intraocular pressure or IOP) although some patients develop nerve damage at a relatively low intraocular pressure, while other patients may have a high intraocular pressure for years and yet never develop optic nerve head damage. Untreated glaucoma leads to permanent damage of the optic nerve and a resultant visual field loss, which can progress to visual loss and ultimately to blindness.
Glaucoma can be divided into two main types: "open angle" and "closed angle" glaucoma. Closed angle glaucoma can occur suddenly and is often painful; visual loss can progress quickly but the discomfort often leads patients to seek medical attention before permanent damage occurs. Open angle glaucoma is chronic and tends to progress at a much slower rate and the patient may not notice that they have lost any visual field until the disease has progressed significantly.
Glaucoma is mainly treated with eye drops which can be very effective. Some patient require laser treatment (laser trabeculoplasty) and a small proportion require glaucoma drainage surgery (trabeculectomy), which is often undertaken under "twilight anaesthesia".
