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    Is there hope for patients unable to receive a donor cornea?

    Relieving corneal oedema through the creation of fine corneal incisions

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    Dr Singh
    Corneal transplantation is one of the most frequently performed and the most successful of human transplant procedures. Techniques in corneal surgery have improved dramatically over recent years with more sophisticated operating microscopes and finer surgical instrumentation; the prognosis for a good surgical result in corneal transplantation is generally excellent. Indeed a successful corneal transplant is seen in more than 90% of cases. The waiting lists, however, for suitable transplantable donor material can be long, and there is always a need for more donor tissue. Further, in certain areas of the world, it is extremely difficult to obtain donor corneas.

    Daljit Singh MD from Amritsar, India — a country that suffers from a severe lack of donor corneas — has developed a technique that could offer an alternative treatment approach where donor corneas are not available. Early results of this new procedure have been promising and were presented at the 2005 American Society of Cataract and Refractive Surgery meeting.

    Having extensively studied the lympatics within and around the cornea and conjunctiva, Singh theorized that, by relieving corneal oedema through the creation of fine corneal incisions or pits, most eyes with corneal decompensation could be treated without requiring a corneal transplant. Singh has put his theory into practice and is delighted with the results.

    Discovering lympathics


    Figure 1: Limbal and conjunctival lymphatics. The lymphatics are straight at the corneal end and anastomose freely under the conjunctiva.
    His path to discovery began more than five years ago when a routine glaucoma operation inspired research into conjunctival and corneal lymphatics — proving their existence and their role in corneal complications. "By injecting trypan blue into the extreme periphery of the cornea, lymphatics were seen to arise from all around the cornea as fine channels perpendicular to the limbus, which then joined each other and formed many sacculated and non-sacculated channels running parallel to the limbus and finally ending as two single channels, one at the upper fornix and another at the lower fornix," says Singh. His curiosity led him to pursue this line of research further, which culminated in the full charting of a gross and fine lympathic channel network and its relationship with the cornea (Figure 1).

    "I examined small corneal abscesses and was stunned at the speed with which the myriads of inflammatory cells appeared and disappeared from the inflamed areas," added Singh. Having established the presence of a generous network of channels throughout the cornea, Singh concluded, "at the periphery of the cornea this network is intimately linked with the ends of vascular capillaries and this gives rise to the activation of rapid inflammatory cellular responses. This explains the rapid movement of corneal infections."

    "I believe that wherever there is fluid, there is fluid movement and the cornea is no exception. The endothelium most likely regulates the fluid closest to it and the rest moves forward, irrigates the cornea from inside out and moves out of the anterior corneal layers into the pericorneal lymphatics. The oxygen, in contrast, travels from the surface inwards," postulated Singh. "Corneal oedema reduces both of these processes and inflicts further corneal damage," he concluded.

    Testing the theory


    Figure 2: 85-year old patient after receiving hypertonic saline drops every five minutes for two hours. Hypertonic saline could not clear the cornea.
    It was his years of research, revelations and theories that led Singh to perform his pioneering technique, involving the creation of multiple vertical pits in the cornea to relieve corneal oedema, in an 85-year old male corneal decompensation patient.

    Singh suggested that, by making corneal pits, thus speeding up fluid flow from the deep to the superficial layers of the cornea, a further outward drainage of moving fluid by the lymphatics could reduce corneal water logging.

    Singh's 85-year old patient had only one eye, which had received cataract surgery and iris claw lens implantation 18 years earlier. The patient urgently needed a donor cornea, however because of a lack of donor availability and the patient's inability to pay for the treatment, Singh suggested his alternative therapy (Figure 2).

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