Keratoplasty

Keratoplasty, also called corneal grafting or corneal
transplantation, is an operation in which the patient's
diseased cornea is replaced by the donor's healthy
clear cornea.
Types
1. Penetrating keratoplasty (full-thickness grafting)
2. Lamellar keratoplasty (partial-thickness grafting).
Indications
1. Optical, i.e., to improve vision. Important indications
are: corneal opacity, bullous keratopathy, corneal
dystrophies, advanced keratoconus.
2. Therapeutic, i.e., to replace inflamed cornea not
responding to conventional therapy.
3. Tectonic graft, i.e., to restore integrity of eyeball
e.g. after corneal perforation and in marked corneal
thinning.

4. Cosmetic, i.e., to improve the appearance of the eye.
Donor tissue
The donor eye should be removed as early as
possible (within 6 hours of death). It should be stored
under sterile conditions.
Evaluation of donor cornea. Biomicroscopic
examination of the whole globe, before processing
the tissue for media stroage, is very important. The
donor corneal tissue is graded into excellent, very
good, good, fair, and poor depending upon the
condition of corneal epithelium, stroma, Descemet's
membrane and endothelium (Table 5.1).
Methods of corneal preservation
1. Short-term storage (up to 48 hours). The whole
globe is preserved at 4oC in a moist chamber.
2. Intermediate storage (up to 2 weeks) of donor
cornea can be done in McCarey-Kaufman (MK)
medium and various chondroitin sulfate enriched
media such as optisol medium.
3. Long-term storage up to 35 days is done by
organ culture method.
Surgical technique
1. Excision of donor corneal button (Fig. 5.23A).
The donor corneal button should be cut 0.25 mm
larger than the recipient, taking care not to damage
the endothelium.
2. Excision of recipient corneal button. With the
help of a corneal trephine (7.5 mm to 8 mm in size)
a partial thickness incision is made in the host
cornea (Fig. 5.23B). Then, anterior chamber is
entered with the help of a razor blade knife and
excision is completed using corneo-scleral scissors
(Fig. 5.23C).
3. Suturing of corneal graft into the host bed (Fig.
5.23D) is done with either continuous (Fig. 5.23E)
or interrupted (Fig. 5.23F) 10-0 nylon sutures.
Complications
1. Early complications. These include flat anterior
chamber, iris prolapse, infection, secondary
glaucoma, epithelial defects and primary graft
failure.
2. Late complications. These include graft rejection,
recurrence of disease and astigmatism.