[Morphological changes in rabbit cornea after implantation of a new keratoprosthesis supporting plate]

PURPOSE

To evaluate biocompatibility of the new keratoprosthesis supporting plates (KSP) in rabbits in vivo.

MATERIAL AND METHODS

The study included 15 chinchilla rabbits. In the first group (5 rabbit eyes) KSP made of hydrophobic acryl with square penetrating holes of 220×220 micron (model 1) were inserted into rabbits' corneas. In the second group (5 eyes), KSP made of hydrophobic acryl were used that had trapezoidal fenestrations with size (from 170×130 micron to 180×70 microns) gradually changing from periphery to the center of KSP (model 2). The control group rabbits (5 eyes) had ¹/₂ of Fyodorov-Zuev KSP made of titanium implanted. All animals were observed for up to 3 months with biomicroscopy and optical coherence tomography of the anterior segment. The animals were then euthanized and had their corneo-scleral discs excised and then examined with optical microscopy and scanning electron microscopy (SEM).

RESULTS

After 3 months, there was only one case of KSP protrusion in the first group. In the second group, thinning of the corneal layers above the central part of KSP occurred in one case. The presence of polymer KSP (of both models) in the corneal stroma was found not to cause formation of rough fibrotic tissue. At the same time, adhered cellular and fibrous elements were discovered on the surface and inside the holes of the polymer KSP, while on the surface of the titanium plate cellular elements were absent.

CONCLUSION

Supporting plates made of hydrophobic acrylic material can potentially serve as a foundation for the new keratoprosthesis design.

[Staged complex treatment of paralytic lagophthalmos (case report)]

Paralytic lagophthalmos, resulting from facial nerve palsy, is a difficult medical and social issue that requires cooperation of different specialists. Complications that arise in paralytic lagophthalmos may cause significant vision loss and even eye loss. Various techniques of paralytic lagophthalmos correction are used to protect the cornea and restore eyelid anatomy and functions. These comprise palliative (conservative), surgical, and alternative treatments (such as botulinum toxin type A therapy). Surgical treatment of paralytic lagophthalmos patients often has to be staged and complex. This article presents a clinical case of a female patient with paralytic lagophthalmos complicated by corneal perforation. Her staged complex treatment included lower eyelid surgery, chemodenervation of the upper eyelid levator and optical reconstructive surgery. The following positive results were achieved: the protective function of the eyelids was restored, residual visual functions - preserved, the risk of eye loss - eliminated, and the asymmetry between the two halves of the face - corrected.

[The role of eye tissue bank in cornea transplantation]

Cadaveric human cornea transplantation is impossible without a specialized tissue donor service, Eye Tissue Bank. An original medical technological system of Eye Tissue Bank was developed at Fyodorov Eye Microsurgery Complex, a federal state institution. The system is still unique in the world; it is grounded upon the concept of the pharmacological protection of the graft and is oriented towards prevention of energodeficiency both in donor cornea and in the recipient's organism at all stages from the selection and preservation of cadaveric material till postoperative pharmacological correction of the recipient. The working experience of Eye Microsurgery Complex has shown the significance of the developed medical technological system for clinical ophthalmology and rehabilitation of the blind and patients with impaired vision in Russian Federation.

[Achievements of S. N. Fyodorov's school in the field of keratoplasty and cornea replacement]

Reduction in corneal transparence leading to the loss of sight may be caused by different factors, such as eye burns and injuries, keratitis, corneal ulcers, primary and secondary dystrophy, keratoconus, and keratoglobus. In many cases, keratoplasty presents an effective treatment. S. N. Fyodorov made a great contribution to the development of cornea replacement. This was him who placed the entire ophthalmology, including keratoplasty, at the microsurgical level, suggested the use of large-diameter grafts, and was the initiator of establishing the first Eye Tissue Bank. Perfection of microsurgical technique, selection and protection of the graft, as well as new approaches to pre- and postoperation therapy have provided transparent engrafting in 35 to 95%. Presently, Eye Microsurgery Complex is the only Russian institution where the problem of cornea replacement is being worked out as a scientific and practical issue. Three models of keratoprosthesis have been developed: Fyodorov-Zuyev model for implantation into a burn leukoma, Moroz-Glazko model for implantation into a dystrophic leukoma, and a "grid" for implantation into a leukoma of any etiology.