Post-penetrating keratoplasty glaucoma

Abstract

Post-penetrating keratoplasty (post-PK) glaucoma is an important cause of irreversible visual loss and graft failure. The etiology for this disorder is multifactorial, and with the use of new diagnostic equipment, it is now possible to elucidate the exact pathophysiology of this condition. A clear understanding of the various mechanisms that operate during different time frames following PK is essential to chalk out the appropriate management algorithms. The various issues with regard to its management, including the putative risk factors, intraocular pressure (IOP) assessment post-PK, difficulties in monitoring with regard to the visual fields and optic nerve evaluation, are discussed. A step-wise approach to management starting from the medical management to surgery with and without metabolites and the various cycloablative procedures in cases of failed filtering procedures and excessive perilimbal scarring is presented. Finally, the important issue of minimizing the incidence of glaucoma following PK, especially through the use of oversized grafts and iris tightening procedures in the form of concomitant iridoplasty are emphasized. It is important to weigh the risk-benefit ratio of any modality used in the treatment of this condition as procedures aimed at IOP reduction, namely trabeculectomy with antimetabolites, and glaucoma drainage devices can trigger graft rejection, whereas cyclodestructive procedures can not only cause graft failure but also precipitate phthisis bulbi. Watchful expectancy and optimal time of intervention can salvage both graft and vision in this challenging condition.

Figure 1

(A) Graft corneal edema due to peripheral anterior synechiae (PAS) and secondary glaucoma. (B) PAS - gonioscopic view

Figure 2

PAS on ultrasound biomicroscopy (UBM) (copyright owner Lippincott, Williams and Wilkins, 2008)

Figure 3

Graft host junction (GH Jn) synechia on UBM (copyright owner Lippincott, Williams and Wilkins, 2008)

Figure 4

Both PAS and GH Jn synechiae (copyright owner Lippincott, Williams and Wilkins, 2008)

Figure 5

Central iris corneal synechia with ACIOL tilt (copyright owner Lippincott, Williams and Wilkins, 2008)

Figure 6

IOL iris synechia (copyright owner Lippincott, Williams and Wilkins, 2008)

Figure 7

PK with concomitant iridoplasty (courtesy of Dr. Namrata Sharma, Dr. R.P. Centre)