Penetrating Keratoplasty and Glaucoma (PKPG)

Updated: Aug 10, 2018
  • Author: Kristin Schmid Biggerstaff, MD, MS; Chief Editor: Hampton Roy, Sr, MD  more...
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Glaucoma following penetrating keratoplasty (PKP) is one of the most common causes for irreversible visual loss and the second leading cause for graft failure after rejection. The management of penetrating keratoplasty and glaucoma (PKPG) remains controversial mainly because of the high risk of graft failure associated with the treatment.

Recent developments in the management of glaucoma, including newer classes of drugs, surgical procedures (eg, trabeculectomy with mitomycin-C), glaucoma drainage devices (GDDs), and cyclodestructive procedures with Nd:YAG and diode lasers, have increased the options available to the clinician in the management of PKPG.

This article addresses the etiology, diagnosis, and treatment of PKPG.


History of the Procedure

In 1969, Irvine and Kaufman reported the high incidence of increased intraocular pressure (IOP) following PKP. [1] They reported a mean maximum pressure of 40 mm Hg in aphakic transplants and 50 mm Hg in combined transplants and cataract extraction in the immediate postoperative period. Since then, numerous authors have reported on the incidence and management of PKPG.




The incidence of PKPG varies from 9-31% in the early postoperative period [2, 3, 4] and from 18-35% in the late postoperative period. [1, 2, 4, 5, 6]



The important risk factors for glaucoma in patients undergoing PKP include aphakic and pseudophakic bullous keratopathy, mesodermal dysgenesis, irido-corneal-endothelial syndrome, preexisting glaucoma, perforated corneal ulcer, adherent leukoma, previous PKP, posttraumatic cases, combined PKP and intracapsular cataract extraction, and performance of vitrectomy during PKP. [1, 2, 3, 4, 5, 6, 7, 8] A 10-year retrospective cohort study of 1657 eyes identified the strongest risk factors to be preoperative glaucoma (or IOP >20 mm Hg), aphakic postoperative lens status, and intraocular lens (IOL) removal/exchange associated with keratoplasty. [9]

In addition, the indication for grafting should be considered. In particular, bullous keratopathy, trauma, herpes simplex infection, and corneal ulceration or perforation are associated with higher risk for PKPG than are keratoconus, stromal dystrophies, and Fuchs dystrophy.. [10, 11, 12, 13]

The causes for elevated IOP in the early postoperative period are as follows:

  • Postoperative inflammation

  • Viscoelastic substances

  • Wound leak with angle closure

  • Operative technique

    • Tight suturing and long bites with compression of the angle

    • Larger recipient bed with same size donor button

    • Increased peripheral corneal thickness

  • Pupillary block glaucoma

  • Preexisting glaucoma

  • PKP in aphakic eyes secondary to mechanical angle collapse

The causes for elevated IOP in the late postoperative period are as follows:

  • PKP in aphakic eyes

  • PKP combined with cataract extraction

  • Preexisting glaucoma

  • Steroid-induced glaucoma

  • Graft rejection with glaucoma

  • Ghost cell glaucoma

  • Misdirected aqueous or ciliary block (malignant) glaucoma

  • Epithelial downgrowth

  • Fibrous ingrowth



The pathophysiology of PKPG is multifactorial; it may be related to distortion of the angle with collapse of the trabecular meshwork, suturing technique, postoperative inflammation, corticosteroid use, repeated corneal transplantation, and peripheral anterior synechiae (including prior history of uveitis). The usual factors that contribute to postoperative glaucoma, such as preexisting glaucoma, postoperative inflammation, use of viscoelastic substances, iatrogenic injury to the angle, and steroid-induced glaucoma, [2] should be considered. Zimmerman et al demonstrated on eye bank human eye models that the depth of sutures during PKP can disrupt outflow channels of the trabecular meshwork via weakening of the iridocorneal angle support, particularly in aphakic eyes. [14]

Rumelt et al reports the incidence of various etiologies of PKPG as closed angle (59%), corticosteroid induced (21%), open angle (11%), angle recession (3%), aqueous misdirection (3%), and unknown cause (3%). [15]

Dada et al reported ultrasound biomicroscopy (UBM) findings in 31 eyes with postkeratoplasty glaucoma. [16] The types of synechiae noted on UBM included peripheral anterior synechiae in 30/31 (96.7%) eyes, synechiae at the graft-host junction in 13/31 (41.93%) eyes, both peripheral anterior synechiae and graft-host junction synechiae in 12/31 (38.7%) eyes, central iridocorneal synechiae in 6/31 (19.3%) eyes, and intraocular lens iris synechiae in 3/31 (9.6%) eyes. The authors concluded that secondary angle closure caused by anterior synechiae formation is one of the important causes of PKPG in eyes with opaque grafts. The authors also concluded that UBM serves as a useful tool for anterior segment evaluation in such cases and can help in planning the site for glaucoma filtering surgeries and drainage devices.

Other factors that are peculiar to patients who have undergone keratoplasty exist. Olson and Kaufman, using a mathematical model, proposed that the elevated IOP following keratoplasty in an aphakic patient might be the result of angle distortion secondary to a roll of excess compressed tissue in the angle. [17] Because of edema and inflammation, trabecular meshwork function is compromised. According to Olson and Kaufman, factors that contribute to angle distortion include tight suturing, long bites (more compressed tissue), larger trephine sizes, smaller recipient corneal diameter, and increased peripheral corneal thickness. [17] Conversely, less tight wounds, smaller trephine sizes, donor corneas larger than the recipient, thinner recipient corneas, and larger overall corneal diameter tend to alleviate the angle distortion. Therefore, donor corneal size should be kept at least 0.5 mm or larger. [18]



The diagnosis of PKPG is made based on IOP measurements in the early postoperative period, and, in the late postoperative period, it is based on IOP, optic disc changes, and progressive visual field changes. Patients with extremely high IOPs might present with graft edema and/or failure.



Indications are discussed in other sections.


Relevant Anatomy

Relevant anatomy is discussed in other sections.



Contraindications are discussed in other sections.