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    Stripping corneal surgery of complications

    A focus on DSAEK

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    Massimo Busin, MD
    During the last century penetrating keratoplasty (PK) has established itself as the surgical procedure of choice for the treatment of corneal diseases. Although the results of PK have substantially improved over time and the prognosis of most grafts is extremely good, several problems remain unsolved. The main negative aspect of the conventional technique is associated with the need to retain watertight sutures for at least one year after surgery. As a result, the regularity and stability of corneal shape are affected and vision is reduced by astigmatism, often of high-degree and/or irregular type. Even after suture removal, a relatively large percentage of patients (up to 20%) experience refractive errors that cannot be corrected adequately with spectacles and require the use of hard contact lenses or additional surgical procedures. On the other hand, sutures cannot be kept in place indefinitely, as spontaneous rupture with possible infection and/or graft rejection is possible.

    Where did it all begin?

    In those patients suffering from endothelial decompensation (both primarily, i.e., Fuchs dystrophy, and secondarily after cataract surgery) but with an otherwise healthy cornea, simple "substitution" of the diseased endothelium with donor cells would succeed in both treating the pathologic condition and eliminating most of the complications related to conventional PK surgery.


    Figure 1: Schematic representation of posterior lamellar keratoplasty according to Tillet (courtesy of Prof. G. van Rji, Rotterdam, Holland). The procedure included: A 180░ superior clear-cornea incision (part A); Hand dissection of the deep stroma using a spatula (part B); Excision of a lamella including deep stroma and endothelium from the recipient cornea (part C); Dissection of a similar donor lamella from a donor whole globe and preparation of suture for fixation in the recipient bed (part D); Insertion of the graft into the anterior chamber and fixation with trans-corneal sutures (part E); wound closure with interrupted sutures (part F).
    The idea of a posterior lamellar keratoplasty (PLK) is not new. As early as the mid-fifties, Tillet (Figure 1) had conceived such a procedure, albeit without clinical success, and about 10 years later JosÚ Barraquer had repeated the same negative experience. It must be taken into account, however, that during those years, corneal dissection was performed without the aid of a surgical microscope and, most importantly, there was practically no knowledge of endothelial physiology. It is therefore no surprise that the procedure was associated with the occurrence of intense interface opacity and early graft decompensation.

    All was not forgotten

    Posterior lamellar keratoplasty was forgotten for three decades, until in 1993 Ko presented a poster at the annual ARVO meeting in Fort Lauderdale, describing a new technique of PLK in a rabbit model: both removal of the posterior lamella from the recipient and implantation of the donor posterior graft were performed through a sclero-corneal tunnel without "touching" the anterior corneal surface. However, hand-dissection of the recipient cornea was difficult and the resulting surface, even in the best cases, was never of an optical quality compatible with 20/20 vision.

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    Massimo Busin, MD
    Massimo Busin, MD is Head of the Department of Ophthalmology, Villa Serena Hospital in Forli, Italy. He may be reached by E-mail.

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