A successful corneal graft requires both clarity and an acceptable refraction. A clear corneal graft may be an optical failure if high
astigmatism limits visual acuity. Intraoperative measures to reduce postkeratoplasty
astigmatism include round and central
trephination of cornea with an adequate size, appropriate
sutures with evenly distributed tension, and perfect graft-host apposition.
Suture manipulation has been described for minimising early postoperative
astigmatism. If significant
astigmatism remains after
suture removal, which cannot be corrected by optical means, then further
surgical procedures containing relaxing incisions, compression
sutures,
laser refractive surgery, insertion of intrastromal corneal ring segments, wedge resection, and toric
intraocular lens implantation can be performed. When
astigmatism cannot be reduced using one or more abovementioned approaches, repeat
penetrating keratoplasty should inevitably be considered. However, none of these techniques has emerged as an ideal one, and corneal surgeons may require combining two or more approaches to exploit the maximum advantages.