Post graft lenses
Spectacles can only be used to manage primary corneal ectasias in the early stages. The primary corneal ectasias include eye conditions like keratoconus, keratoglobus and pellucid marginal degeneration. Keratoconus is the most commonly encountered of these diseases and a separate page is dedicated to keratoconus contact lens management. All corneal ectasia conditions are characterized by corneal thinning and ectasia (this is the irregular and asymmetrical disturbance of the corneal shape- in keratoconus occurs as a protrusion of the normal corneal shape into a conical irregular corneal shape). Corneal ectasia results in varying degrees of irregular astigmatism and distorted vision.
Penetrating keratoplasty (corneal transplant or graft surgery) is performed when all other options in the presence of a progressed corneal ectasia, have failed and the visual acuity remains severely reduced. In fact 60% of transplanted patients are patients who suffer from keratoconus. A corneal transplant is an operation used to remove all (full thickness graft) or part (lamellar or deep lamellar) of a damaged cornea and replace it with healthy cornea tissue from the eye of a suitable donor. Corneal graft sizes range from 7.5 to 8.5 mm and sutures used to keep the graft in place can be radially interrupted sutures or a single continuous suture. After the operation the surgeons’ care is focused on controlling inflammation and preventing infection with the use of corticosteroids and the prophylactic use of antibiotics.
However, according to studies carried at London’s Moorfields Eye Hospital approximately 30%- 50% of eyes that undergone a corneal transplant will still benefit from a contact lens in order to achieve adequate vision after the graft surgery. Contact lens fitting can typically start 6 to 12 months after surgery following removal of sutures but the cornea as a whole may take up from 18 to 24 months to reach complete tissue healing and stability. Partial and not full thickness grafts have a faster recovery time but in any case if you have undergone any type of corneal transplant is extremely important to take good care of your eye to improve your chances of a good recovery. This includes advice such as no rubbing your eye and avoiding activities such as contact sports and swimming until you are told by your surgeon that it is safe to do so.
Fitting contact lenses post penetrating keratoplasty can be challenging since every graft is different. At Xenophontos Opticians past hospital experience as well as years of fitting post grafted patients, has given us the confidence and essential experience for encountering such difficult fits. Despite advances in surgical techniques for corneal transplants, myopia and high degrees of irregular astigmatism remain common. Perfectly centered grafts are not always possible and in fact very frequently the graft is tilted with the host/graft junction often being irregular. Your fitter will respect the physiology and new shape of your ‘new cornea’ during the contact lens fitting. High oxygen gas permeable materials are usually the first choice for grafted corneas (the need for oxygen supply is increased in a grafted cornea especially along the junction of the host/donor cornea) and this is one of the reasons your optometrist will take extreme care of the host/donor graft margin when performing the aftercare visits of the final lens prescribed. Other reasons, involve eliminating mechanical stress of the contact lens which is resting and gently moving along the different topographic areas of your grafted cornea. We recommend our post graft fitted patients to keep their aftercare routine appointments every six months unless advised otherwise. Post graft contact lens patients are carefully educated on all aspects of careful contact lens care and handling since lens hygiene is of extreme importance in these cases.