Customised component corneal transplantation: a blessing for three patients

An Overview of Corneal Transplantation in the Past Decade

The cornea is a transparent avascular structure located in the front of the eye that refracts light entering the eyes and also serves as a barrier between the outside world and the internal contents of the eye. Like every other body part, the cornea may suffer insult from trauma, infection, and inflammation. In the case of trauma, a prior infection that left a scar, or conditions such as keratoconus that warrant the removal of all or part of the cornea (keratoplasty), it is important to use healthy donor corneal tissues and cells that can replace the damaged cornea. The types of cornea transplant techniques employed currently include: penetrating keratoplasty, endothelial keratoplasty (EK), and artificial cornea transplant. Postoperative failure acutely or after years can result after a cornea transplant and may require a repeat transplant. This minireview briefly examines the various types of corneal transplant methodologies, indications, contraindications, presurgical protocols, sources of cornea transplant material, wound healing after surgery complications, co-morbidities, and the effect of COVID-19 in corneal transplant surgery.

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.

Component corneal surgery: An update

Several decades ago, penetrating keratoplasty was a challenge to corneal surgeons. Constant effort by the corneal surgeon to improve the outcomes as well as utilization of the available resources has led to a revolutionary change in the field of keratoplasty. All these efforts have led to the evolution of techniques that allow a corneal surgeon to disease-specific transplant of individual layers of corneal “so-called component corneal surgery” depending on the layer of cornea affected. This has led to an improvement in corneal graft survival as well as a better utilization of corneal tissues. This article reviews the currently available literature on component corneal surgeries and provides an update on the available techniques.