[Depth of lamellar keratoplasty with the guided trephine system for transplantation of full-thickness donor sections]

Histologic findings of recipient corneas obtained via deep anterior lamellar keratoplasty

PURPOSE

We sought to investigate the histologic findings of recipient corneas obtained via deep anterior lamellar keratoplasty (DALK).

METHODS

The histology of three recipient corneas obtained from patients during DALK was investigated. In all cases, the Descemet membrane was successfully exposed without any perforation during surgery. The isolated corneal tissue was stained with hematoxylin-eosin and periodic acid-Schiff. In two cases, the tissues were examined using a transmission electron microscope.

RESULTS

In one cornea obtained via DALK, only the corneal stroma was observed, and the Descemet membrane was not confirmed. In another case, the recipient cornea was detached within the Descemet membrane. In the third cornea, the banded layer membrane was partially confirmed.

CONCLUSIONS

These findings suggest that the recipient corneas separated at different layers during the DALK procedure. With our surgical technique, the detachment of the Descemet membrane may occur at a mechanically weak segment. This separation site may not be between the Descemet membrane and the corneal stroma.

Deep lamellar keratoplasty by deep parenchyma detachment from the corneal limbs

AIM

To improve the deep lamellar keratoplasty technique.

METHOD

For the easy and reliable perfomance of deep lamellar keratoplasty (DLKP), detachment of Descemet's membrane through the corneal limber flap was improved. To expose Descemet's membrane, the parenchyma was detached by hydrodelamination through a sclerocorneal flap made in the corneal limbs. The parenchyma was removed after the pseudochamber between it and Descemet's membrane was maintained with viscoelastic material. The corneal graft was placed with a running suture. 22 eyes were treated.

RESULTS

Complete exposure of Descemet's membrane was obtained in 20 of the 22 eyes (91%). The membrane was perforated in five of the 22 eyes (23%) during surgery, and two of the 22 eyes (9%) were converted to penetrating keratoplasty. These two eyes developed keratoconus after acute corneal hydrops.

CONCLUSION

Compared with the conventional procedure, this new method provides easy, reliable exposure of Descemet's membrane.

Lamelläre Keratoplastik

In 1840 Mühlbauer was the first to describe a technique for anterior lamellar keratoplasty (LKP). However, in the second half of the twentieth century penetrating keratoplasty (PKP) became the gold standard. Although it is associated with a higher risk for serious complications -- it is technically easier to perform and avoids wound healing reactions in the lamellar interface and thus resulting in better visual acuity. In view of the pathology, replacing all layers of the cornea including healthy parts can be considered therapeutic "overkill" for many corneal graft indications. Several innovative surgical techniques have recently been described which allow the lamellar dissection of recipient and donor cornea with good reproducibility in almost every desired depth. This now allows the recipient endothelium and Descemet's membrane to be selectively replaced or preserved and to avoid formation of an optical barrier in the lamellar interface in eyes undergoing lamellar keratoplasty for optical indications. The most important principal advantage of an anterior LKP -- to minimize the risk of an immune reaction in the graft -- is even more important in tectonic indications. From the large number of variations, the surgical technique, results, and problems with anterior and posterior LKP for optical indications as well as lamellar segment keratoplasty and epikeratoplasty for tectonic indications are discussed.

Surgical Treatment of Keratoconus at the Turn of the 20th Century

PURPOSE

This paper reviews surgical modalities for treatment of keratoconus at the threshold of the 20th century.

METHODS

All ophthalmic literature from 1895 until 1925 in English and German, available at the library of the Institute of Ophthalmology, London, United Kingdom, was studied with respect to this topic.

RESULTS

Three thermal procedures were described; galvanocauterization with perforation, without perforation, and a non-contact application of heat to the corneal apex. Radial extension of a thermal burn to correct the minus cylinder represented a further modification. Excision of the conical area was suggested either as a lamellar dissection or as a full thickness trephination. Incision of the cone appeared to be less popular. In staged procedures, a combination of galvanocauterization, splitting of the cornea, conjunctival flap, and a subsequent optical iridectomy were applied.

CONCLUSION

The treatment of keratoconus 100 years ago used refractive surgery to improve visual function by modifying corneal shape.