Managing Positive Vitreous Pressure in Penetrating Keratoplasty: Techniques and Challenges

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Positive vitreous pressure (PVP) is an uncommon but serious complication that can arise during penetrating keratoplasty (PKP), posing a risk to vision, particularly when accompanied by choroidal hemorrhage. Limited information is available regarding the occurrence of PVP during PKP, but studies find an incidence rate of 3.6% to as high as 40–50%[1][2][3][4]. Given the potential sight loss, it is crucial to identify surgical approaches that minimize intraoperative complications while ensuring the preservation of the donor corneal tissue.

Pathophysiology of PVP

Positive vitreous pressure (PVP) can occur during penetrating keratoplasty (PKP) and intraocular anterior segment procedures due to acute hypotony resulting from open-sky surgery[5]. The condition involves a gradual increase in vitreous cavity pressure relative to volume reduction that can be caused by external compression or intraoperative swelling. This concurrent aqueous loss and hypotony creates a pressure gradient between the vitreous cavity and the anterior chamber, resulting in displaced vitreous content.

This condition manifests as the anterior chamber exhibiting a resistant shallowing with the lens-iris diaphragm displaced forward[5]. And it can be marked by recurring instances of iris prolapse and, in severe cases, the occurrence of zonular rupture alongside the possibility of vitreous or lens prolapse.

Prolonged and acute hypotony during PKP can increase transmural pressure, resulting in vessel rupture and the potential development of sight-threatening suprachoroidal hemorrhage.[6]

Risk Factors of PVP

  • Patient risk factors:
    • Increased systemic venous pressure due to
      • Positioning of the head below the heart
        • Congestive heart failure
        • Pulmonary edema
        • Obstructive sleep apnea
        • Chronic obstructive pulmonary disease
        • Valsalva maneuver
        • Severe obesity
        • Poorly positioned bull-necked patients with elevated venous pressure in the head
        • Rare cases of arteriovenous fistula
      • Younger age
        • Infants may have less rigidity and increased elasticity of the cornea and sclera, contributing to iris-lens diaphragm movement[7]
      • Other risk factors:
        • Blood dyscrasias or coagulation defects[8]
        • Diabetes mellitus[8]
        • History of liver disease[8]
        • Preoperative use of digoxin[8]
        • Anxiety, which has been associated with higher PVP risk
  • Ocular risk factors:
    • Ocular disorders:
      • Iris pathology
      • Presence of zonular instability
      • Shallow anterior chamber
      • Acute angle-closure glaucoma
    • Additional risks in patients with pseudophakia:
      • Ruptured capsule or IOL location outside the bag[9]
      • Presence of an IOL or iris prolapse in pseudophakic or aphakic eyes is strongly correlated with a 100% incidence of PVP[10]
    • Eye conditions:
      • Poor rigidity (i.e. keratoconus)
      • High myopia, High axial length of the eye leading to decreased orbital volume and increased pressure on globe
      • Buphthalmos
      • Short axial length
      • large crystalline lens
    • Orbital-related risk factors:
      • External compression during surgery (example: Lid speculum pressure on the eye)
      • Strong blink reflex
      • Anatomically small orbit or orbital deformity
      • Increased orbital tissue pressure from increased volume or fluid, such as retrobulbar or intraorbital hemorrhage
      • Orbital congestion from inflammation or edema (e.g., thyroid-related ophthalmopathy, orbital inflammatory syndromes)
      • Orbital tumors
      • Increased orbital fat in patients with marked obesity
    • Other risk factors:
      • History of infectious keratitis, ocular inflammation, or glaucoma (mechanism remains unknown)
  • anesthesia risk factors
    • peribulbar anesthesia> general anesthesia
    • general anesthesia
    • positive end-expiratory pressure (PEEP) during general anesthesia
  • surgeon risk factors
    • operating with the open-sky technique
    • length of time globe is open[3]



  • Graft-over-host Technique
  • Modified Graft-Over-Host Technique
  • Mattress Sutures and Needle Techniques
  • Vitrectomy or Vitreous aspiration


  1. Dekaris I, Gabric N, Pauk M, Drača N. Positive pressure during penetrating keratoplasty can be solved with a modified graft-over-host technique. Acta Ophthalmol. 2014;92(3):282–285. doi:10.1111/AOS.12085
  2. Konomi K, Shimazaki J, Shimmura S, Akabane N, Goto E, Tsubota K. Efficacy of core vitrectomy preceding triple corneal procedure. Br J Ophthalmol. 2004;88(8):1023–1025. doi:10.1136/bjo.2003.033902
  3. 3.0 3.1 Shimomura Y, Hosotani H, Kiritoshi A, Watanabe H, Tano Y. Core vitrectomy preceding triple corneal procedure in patients at high risk for increased posterior chamber pressure. Jpn J Ophthalmol. 1997;41(4):251–254. doi:10.1016/S0021-5155(97)00046-4
  4. Baratz KH, Pulido JS. Vitreous tapping for positive pressure. Ophthalmology. 2006;113(3):501–502. doi:10.1016/J.OPHTHA.2005.11.014
  5. 5.0 5.1 Chronopoulos A, Thumann G, Schutz J. Positive vitreous pressure: pathophysiology, complications, prevention, and management. Surv Ophthalmol. 2017;62(2):127–133. doi:10.1016/J.SURVOPHTHAL.2016.10.002
  6. Alkharashi M, AlAbdulhadi HA, Otaif W, Alahmadi AS, Alanazi B, Al Habash A, Aldayel A, Aljindan M, Almulhim A, Bin Helayel H. Incidence, Pathophysiology, Complications, and Management of Positive Vitreous Pressure During Penetrating Keratoplasty: A Literature Review. Clin Ophthalmol. 2023;17:583-590
  7. Shimomura Y, Hosotani H, Kiritoshi A, Watanabe H, Tano Y. Core vitrectomy preceding triple corneal procedure in patients at high risk for increased posterior chamber pressure. Jpn J Ophthalmol. 1997;41(4):251–254. doi:10.1016/S0021-5155(97)00046-4
  8. 8.0 8.1 8.2 8.3 Lavinsky F, Moisseiev J, Levkovitch-Verbin H. The surgical management of massive intraoperative and postoperative suprachoroidal hemorrhage: anatomic and functional outcomes. Arq Bras Oftalmol. 2013;76(4):212–214. doi:10.1590/S0004-27492013000400003
  9. Huang X, Zhou Q, Wang S, Zhang J, Niu G, Bi Y. Stepwise decreasing of vitreous pressure by anterior vitrectomy: a novel method for preventing positive vitreous pressure during penetrating keratoplasty. Adv Ther. 2020;37(1):617–629. doi:10.1007/S12325-019-01139-6
  10. Cheung AY, Davis AR, Denny MR, et al. “Basket” mattress suture to manage positive vitreous pressure during penetrating keratoplasty. Can J Ophthalmol. 2020;55(6):509–517. doi:10.1016/J.JCJO.2020.06.012
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