Ocular surface problems
PTK for recurrent corneal epithelial erosion and corneal scars
This is any laser or surgical procedure performed to reduce the refractive error of eyes and reduce or eliminate the need for wearing glasses or contact lenses. This includes surgery for short-sightedness (myopia), long-sightedness (hyperopia), astigmatism or presbyopia (the need for wearing glasses for reading with age).
Refractive surgical procedures include:
Other surgical procedures:
Keratoconus is a degenerative process affecting the cornea, the clear window of the front of the eye, distorting it out of shape and interfering with the focus of the eye. The cornea becomes more conical in shape and this makes vision blurry by making the eye more short-sighted (myopic) and also distorts vision by producing irregular astigmatism (the cornea is not evenly curved). The condition usually affects both eyes but one may be much worse than the other.
Keratoconus is a genetically determined condition but is not necessarily passed on in families. One in twelve people with keratoconus will have an affected relative. If there is not a definite family history then there is a one in ten chance of the children of someone with keratoconus also having it.
Keratoconus is often associated with allergic disorders such as asthma, eczema and hayfever. It is more common in those with Down’s syndrome. It is also more common in people with sleep apnoea syndrome or floppy eyelid syndrome.
There are a number of options for dealing with keratoconus:
Unfortunately, there is very little that one can change in daily life or activity that will make a difference to progression of keratoconus. It is known that eye-rubbing makes it worse and this is more likely to be an issue for people with hayfever and allergies. Using anti-inflammatory eyedrops (Cromo-Fresh, Zaditen or Patanol) can help to reduce itching and the need to rub the eyes. Wearing contact lenses does not prevent keratoconus getting worse. If it is getting worse then it is advisable to have collagen cross-linking performed to stabilise it.
Corneal transplantation is replacement of part of the cornea with human tissue from deceased donors. These are proper transplant procedures with the potential risks associated with that. Satisfactory synthetic grafts are not yet routinely available. Keratoprosthesis (artificial cornea) procedures may be done when standard corneal transplants fail repeatedly or have no hope of surviving and working.
Corneal transplantation is performed for several reasons:
Types of corneal transplants
The traditional method of corneal transplantation has been full thickness transplantation (Penetrating Keratoplasty (PK). This is not a new technique, with the first successful corneal graft being reported in 1905.
More recently there has been a shift to replacement of only the affected layers of the cornea (Lamellar Keratoplasty, LK), including Deep Anterior Lamellar Keratoplasty (DALK) for the front of the cornea and Endothelial Keratoplasty (EK, DSEK, DSAEK, DMEK) for replacement of the posterior layer of the cornea – the corneal endothelium.
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Corneas are donated after death and are processed in the Lions Eye Bank of Western Australia at the Lions Eye Institute. Corneas need to be obtained within 24 hours of death and consent from the next of kin needs to be available within that time even if the deceased has registered as an organ donor. Registration as a donor and discussion of your wishes with next of kin is important if you do wish to donate organs or tissues after death.
To register as an organ and tissue donor see:
The corneas have a number of testing procedures performed and must be used within 4 weeks of donation. We are fortunate to usually have enough donors in Western Australia to be able to schedule corneal transplants within several weeks and also deal with emergency cases. Occasionally corneas need to be obtained from other eye banks around Australia or New Zealand.
There are many potential issues with corneal transplants, though most work very well.
There is a risk of rejection of the graft. This may start to occur in up to 25% of full-thickness grafts but is less common in lamellar grafts. Rejection is usually reversible with treatment. If the graft rejects completely the cornea will go cloudy and the graft may have to be repeated. The chance of a second graft surviving in that case is less than the first.
Corneal grafts do not last forever. Full-thickness grafts may last 25-30 years in very good circumstances but will then need to be repeated as the graft gradually becomes hazy. Endothelial grafts are likely to fail sooner and will need to be replaced more frequently but that is more straightforward than repeating a full-thickness graft.
Rarely a graft will not work right from the start and will need to be replaced straight away.
Some conditions, such as some of the corneal dystrophies, may recur in the graft and require further surgery repeat corneal transplantation.
It is quite common to have an increase in intraocular pressure due to the topical steroid medication used after the surgery (steroid-induced glaucoma). This may require treatment with glaucoma eyedrops or may require surgery itself.
It is possible for the corneal graft to be clear and healthy but for vision to still be poor due to irregular or uneven shape of the cornea (irregular astigmatism).
The donor corneas are screened for the presence of potentially transmissible diseases but despite this there is a very small risk of developing a disease from the graft itself.
Systemic (oral) anti-rejection drugs are not usually used for corneal transplants as they have multiple potentially severe side effects and the survival rate of the transplants is generally very good without them. Drugs are used in the form of eyedrops and may need to be used indefinitely.
Tissue typing is usually not necessary for corneal transplant as the cornea is an immunological privileged site within the body and it does not make a significant difference to the outcome.