Patch Grafting Using a Cryopreserved Descemet Stripping Automated Endothelial Keratoplasty Flap for Treating Corneal Perforation

Modified "Top-up sandwich" technique for the management of corneal perforations: A case report and a literature review

Purpose

We describe a modified technique for managing a peripheral, non-infected, corneal perforation using a "Sandwich" technique that combines posterior lamellar keratoplasty, an amniotic membrane patch and a Gundersen conjunctival flap.

Observations

A 75-year-old female patient presented with Sjogren's syndrome-related corneal perforation. A mini-Descemet stripping automated endothelial keratoplasty (DSAEK) graft (5 mm) was introduced into the anterior chamber and was mobilized to plug the perforation. Then, two amniotic membrane patches were stacked over the perforation and glued. Finally, the whole area was covered with a Gundersen conjunctival flap, mobilized from the inferior conjunctiva and secured in place using interrupted 10-0 nylon sutures. A step-by-step guide is also described. At three months, the final visual acuity was 6/9. A literature review revealed ten cases in which a posterior lamellar graft was effectively employed to treat corneal perforations.

Conclusions and Importance

We described a modified approach for treating peripheral corneal perforation surgically. This "sandwich" approach is simple to replicate and can give quick healing with few visual repercussions. Our detailed guide may be utilized to obtain similar results and may be added to the array of treatment options for peripheral corneal perforation.

Mechanical Stability of Cryopreserved Split-Thickness Tectonic Corneal Grafts

PURPOSE

To evaluate the influence of cryopreservation on the pressure-strain relationship of microkeratome dissected anterior stromal grafts (ASGs).

METHODS

Partial thickness ASGs were created from 7 pairs of human corneas and randomized to immediate grafting or grafting after 3 months of cryopreservation at -80°C into a whole globe ex vivo corneal perforation model. High frequency ultrasound speckle tracking was used to calculate the cross-sectional axial and lateral strains in each graft at increasing intraocular pressure (IOP) from 5 to 30 mm Hg. The mean axial and lateral strains were compared between the paired groups.

RESULTS

The mean axial and lateral strains were not significantly different between the cryopreserved and noncryopreserved ASGs. The mean lateral strains at 30 mm Hg in the noncryopreserved and cryopreserved grafts were 2.4% ± 2.1% and 1.4% ± 0.7% (P = 0.294), respectively. The mean axial strains at 30 mm Hg in the noncryopreserved and cryopreserved grafts were -7.8% ± 3.3% and -5.5% ± 3.0% (P = 0.198), respectively. A linear pressure-strain relationship was found for all grafts at physiologic IOP.

CONCLUSIONS

ASGs cryopreserved at -80°C maintain their IOP-strain relationship compared with noncryopreserved ASGs at physiologic pressures, supporting the potential use of cryopreserved human corneal stroma for patch grafting procedures.

Methods of cadaver donor cornea evaluation for keratoplasty (literature review)

At present time, a large amount of patients with corneal diseases require keratoplasty, therefore there is a quite high demand of constant donor cornea stock. In present article, methods of cadaver donor corneal material analysis are described in a sequence that is necessary for its qualitative assessment before surgery or for the choice of the optimal method of preservation in the Eye Bank conditions. It is known that corneal endothelial cells and their viability play a main role in the maintenance of transparency of transplanted corneal flap after penetrating keratoplasty or endothelial keratoplasty. It is for these types of keratoplasty that the highest quality of donor material with preservation of a large number of viable corneal endothelial cells is needed. Corneal flaps with poorer quality of corneal endothelial layer could be successfully used for different types of anterior lamellar keratoplasty and interlamellar keratoplasty. Therefore the adequate evaluation of donor corneal material before surgery allows reducing the risk of postoperative complications associated with failure of the corneal endothelial layer, and increasing graft survival in patients after surgery. In addition, the choice of the optimal type of preservation is of great relevance for maintaining the corneal material as viable in the long run for various types of transplantations.

[Methods of preserving donor corneas]

Corneal transplantation is the most successful and frequently performed allotransplantation procedure. Benign outcome of penetrating and posterior keratoplasty depends on viability of the corneal tissue and presence of the proper endothelial layer, which retaining is one of the main objectives of preservation of donor material. Methods designed to reach this goal may be classified according to storage duration as short-term (storage in a moist chamber), medium-term (hypothermia), long-term (organ cultivation) and unlimited (cryopreservation). While there are reports of successful application of cryo-conserved corneas for penetrating keratoplasty, its use for this type of transplantation is limited due to complexity of the method and very high requirements for the quality of donor material. However, being a method of unlimited storage, it still attracts the attention of researchers. Taking into account the ongoing development of innovative keratoplasty technologies and the tendency for predominant use of layered grafts that in some cases do not need viable endothelium, methods of preservation of such material for anterior lamellar and intralamellar keratoplasties become relevant. In this context, cryopreservation without the use of cryoprotective agents is promising because it allows simple and fast accumulation of large amount of material with long storage time. Further research on the development of preservation methods of the corneal endothelial layer at sub-zero temperatures may allow storing the material by cryopreservation that will be suitable for penetrating and posterior keratoplasty.