Description

Penetrating keratoplasty (PKP) is a successful procedure for restoring a clear cornea in patients with corneal disease, particularly following recent improvements in microsurgical techniques, suture materials, instrumentation and quality of donor material. Major complications include: primary graft failure; allograft rejection; secondary glaucoma; significant astigmatism and recurrence of the primary pathology. Patient dissatisfaction may be due to a failure of improvement in visual function or asthenopia. The latter may be secondary to glare, anisometropia, aniseikonia or astigmatism. However, significant induced corneal astigmatism remains the single most common factor limiting visual acuity postoperatively. This is despite improvements in trephination, suturing techniques and intra-operative keratometry. Astigmatism may be regular, or highly irregular and asymmetric to such a degree that correction with spectacles or contact lenses may be unsatisfactory, or poorly tolerated, and difficulties with contact lens stability or fit may be insurmountable.