Corneal pathology occupies one of the leading positions among the causes of blindness and low vision. Most commonly, corneal damage results from injuries and burns, which are among the most severe pathologies of the visual organ. According to WHO data, it ranks among the top three main factors of vision loss, accounting for between 6.6% and 39.3%. In particular, corneal injuries in persons of working age account for 29% of the primary disability structure, while the frequency of eye burns, according to various authors, ranges from 6.1% to 38.4% of all types of visual organ injuries.
Traditional conservative treatment technologies for traumatic eye injuries and corneal ulcers do not always produce a positive outcome, which is quite often associated with disruptions in reparative-regenerative processes leading to corneal perforation and loss of the eye. Therefore, corneal pathology frequently requires urgent surgical intervention, especially in cases of progressive lysis and the threat of corneal perforation. This indicates that adequate treatment of patients with visual organ trauma and ulcerative keratitis is a pressing medical, social, and economic problem.
One of the main treatment approaches for patients with visual organ trauma and ulcerative keratitis is keratoplasty. Given the high regenerative capacity of corneal tissue, most clinicians favour the view that surgical treatment of these patients based on the fundamental principles of biological coverage according to N. O. Puchkovska (1985) offers advantages. For this purpose, various donor materials are used, including cornea, sclera, dura mater, fascia, amnion, and others. Although corneal transplantation, as the most widely used transplantation technology at present, has been known for about one hundred years, the difficulties in its implementation continue to form the core of the scientific and practical problem of modern ophthalmology. These include ensuring access to full-quality high-grade donor material, immunological incompatibility between implant tissues and the host organism, and others. This is all the more significant given that under modern conditions — against the backdrop of a sharp increase in road traffic, industrial, and domestic injuries, disruption of the ecological balance in the biosphere, high risk of visual organ trauma, and legal challenges in obtaining allogeneic material for keratoplasty — the problem of donor material shortage has become particularly acute.
For therapeutic and tectonic keratoplasty, we have proposed the use of porcine cornea — a cryolyophilised keratoxenoimplant (N. V. Pasiecnikova, S. A. Yakimenko, M. V. Turchyn).
In developing the technology for the preservation and storage of porcine corneas, account was taken of the positive long-standing clinical experience with the use of cryolyophilised xenogenic porcine skin for the treatment of burn patients (V. V. Bigunyak, 1985–2010).
The production of the cryolyophilised keratoxenoimplant is carried out using a technology developed jointly by the Ternopil State Medical University named after I. Ya. Horbachevsky and the Odesa Institute of Eye Diseases and Tissue Therapy named after Academician V. P. Filatov of the AMS of Ukraine (Pat. 52278 U, 2010). It consists of removing the cornea from a freshly slaughtered pig, treating it under appropriate conditions with a cryoprotectant, preserving it at ultra-low temperature (−196 °C), vacuum drying, passing a technological quality control stage, packaging the product, and sterilising it by radiation. The keratoxenoimplant cryolyophilised in this manner has been registered by the Ministry of Health of Ukraine as a medical device, is stored in a special hermetically sealed package (State Registration Certificate No. 9967/2010), and is approved for use in medical practice.
Specifications
The keratoxenoimplant, as a medical device, is a cryolyophilised tissue substrate of porcine cornea, ready for use in surgical corneal reconstruction according to medical indications.
Instructions
Indications:
for therapeutic keratoplasty:
- keratitis
- corneal ulcers
- corneal dystrophy and perforation resulting from trauma, burns, or infectious complications
- inflammatory corneal diseases
Contraindications:
- significant purulent discharge
Principle of therapeutic action:
mechanical closure of the recipient’s affected cornea and stimulation of its regeneration.
Usage Recommendations:
One hour before the surgical procedure (therapeutic keratoplasty), observing all aseptic and antiseptic rules, the dry keratoxenoimplant is removed from its polyethylene packaging and immersed in a sterile isotonic sodium chloride solution for 50–60 minutes at 18–20 °C. After soaking is complete, the moistened keratoxenoimplant is prepared by shaping a corneal graft of the required size and form to fully cover the patient’s cornea.
Using scissors, excess scleral tissue is trimmed circumferentially from the keratoxenoimplant, leaving 4 projections (approximately at 12, 3, 6, and 9 o’clock) measuring 2–2.5 mm in width and 1–1.5 mm in length for suturing the flap to the ocular sclera (if necessary, a scleral ring of the required width may be retained). For partial coverage, the required disc is cut from the keratoxenoimplant using a trephine.
After standard preparation of the surgical field, a lid speculum and a holding suture on the superior rectus muscle are applied. Local anaesthesia: Sol. Alcaini 0.5% epibulbar, Sol. Lidocaini 2% subconjunctival. The conjunctiva is then dissected from the limbus, the prepared keratoxenoimplant is placed onto the cornea of the affected eye, and sutured to the sclera behind the limbus with 7.0–8.0 sutures at 12, 3, 6, and 9 o’clock. Two sutures are used to fix the conjunctiva for peripheral coverage of the keratoxenoimplant.
An antibiotic solution is instilled into the conjunctival cavity, and an antibacterial ointment is applied. The lid speculum and holding suture are then removed, and a monocular aseptic dressing is applied to the eye.
In the postoperative period, antibiotics and sulfonamide preparations are prescribed in the form of eye drops, which should ideally be potentiated by instillation of non-steroidal anti-inflammatory agents. General anti-inflammatory therapy is prescribed depending on the condition of the eye. Following discharge from hospital, patients continue treatment on an outpatient basis under the supervision of an ophthalmologist at their place of residence until the keratoimplant is fully resorbed and the corneal ulcer has healed. The implanted keratoxenoimplant is fully resorbed within 2–3 months.
Thus, keratoxenoplasty using a keratoxenoimplant based on cryolyophilised porcine cornea ensures closure of the corneal defect with subsequent epithelialisation, reduction and elimination of the inflammatory process, and restoration of the anatomical integrity of the patient’s cornea.
Storage сonditions
Keratoxenoimplants may be stored at a temperature between +5 °C and +25 °C.