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PENTACON Trial: Partial ENdothelial Trepanation in Addition to Anterior Lamellar Keratoplasty in keratoCONus (PENTACON)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01145937
Recruitment Status : Terminated (during anticipated study duration trial power was not attained.)
First Posted : June 17, 2010
Last Update Posted : December 3, 2015
Dr. F.P. Fischer-stichting, Utrecht, The Netherlands
Information provided by (Responsible Party):
R.P.L. Wisse, MD, UMC Utrecht

Brief Summary:


Keratoconus is a progressive, non-inflammatory corneal disease in which irregular refractive properties of the cornea result in loss of visual acuity. Treatment is aimed at improving vision, principally using (rigid) contact lenses. With progression of the disease non-correctable refractive abnormalities and/or corneal scars arise. For these advanced stages of keratoconus, a corneal transplant is the only treatment modality.

New surgical grafting modalities have been developed to create partial thickness grafts, according to the location of corneal pathology. For keratoconus, transplanting only the anterior corneal lamellae lowers long-term graft rejection rates. We utilize a method to enhance the safety of the grafting procedure while better visual outcomes are expected.


To investigate the additional value of partial endothelial trepanation (PET) in an anterior lamellar keratoplasty (ALKP) procedure in terms of efficacy and safety in patients with keratoconus.

Study design:

A randomized controlled interventional trial

Study population:

Patients over 18 years old with keratoconus in whom contact lens correction is unsuccessful and who are not suitable for corneal crosslinking.


Patients will be randomly assigned to corneal grafting techniques; partial endothelial trepanation in addition to an anterior lamellar keratoplasty (i.e. the PET group) or a regular ALKP procedure.

Study outcomes:

Risk of per-operative perforation. Secondary, factors contributing to treatment safety and efficacy.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

There is no extra burden or risk associated with participation in this study. All measurements are part of normal clinical practice. Adequate experience is available with both surgical techniques. Study participation has no effect on donor selection. If partial endothelial trepanation (PET) is associated with lower complication rates and better visual outcomes, this might be beneficial in terms of morbidity.

Condition or disease Intervention/treatment Phase
Keratoconus Procedure: PET Procedure: DALK Not Applicable

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 14 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Pentacon Trial: Partial ENdothelial Trepanation in Addition to Anterior Lamellar Keratoplasty in keratoCONus. A Prospective Multicenter Randomized Controlled Trial
Study Start Date : March 2011
Actual Primary Completion Date : May 2015
Actual Study Completion Date : May 2015

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: PET

Partial endothelial trepanation in addition to anterior lamellar keratoplasty.

The endothelium en Descemet are paracentrally and circular loosened, but some tissue bridges are left in place. This 'island' is able to mould to the healthy donor curvature.

Procedure: PET
Partial Endothelial Trepanation in addition to an anterior lamellar keratoplasty
Other Name: Busin

Active Comparator: DALK
Conventional DALK grafting procedure where the Big Bubble technique is used according to Anwar et al.
Procedure: DALK
Conventional DALK grafting procedure, with Big Bubble technique according to Anwar et al.
Other Name: ALK

Primary Outcome Measures :
  1. Peroperative corneal perforation [ Time Frame: During Surgery. From start to closure of surgical procedure approx. 2h ]
    Peroperative corneal perforation is the biggest drawback of currently utilized grafting procedures (ALKP, 20-30%). Our new technique is believed to be safer, by reducing the number of corneal perforations during surgery. Corneal perforation necessitates converting the procedure to a full-thickness graft with a less favourable long term rejection profile.

Secondary Outcome Measures :
  1. Best corrected visual acuity one year post op [ Time Frame: One year post-op ]
    To determine treatment efficacy visual acuity is assessed one year post-op.

  2. Manifest refraction one year post op [ Time Frame: One year post-op ]
    Manifest refraction can be grossly altered after corneal grafting procedures. To assess this effect, a manifest refraction one year post-op is obtained.

  3. Contact lens use (soft/rigid/scleral) or spectacle use [ Time Frame: one year post-op ]
    To assess the dependency on visual aids after corneal grafting. Residual irregular post-op corneal abnormalities can necessitate (rigid) contact lens wear.

  4. Self-rated improvement questionnaire [ Time Frame: One year post-op ]
    To assess patient satisfaction with treatment outcomes, such as visual acuity, residual refraction etc. This will be measured using the Visual Functioning Questionnaire-25 (Dutch edition).

  5. Corneal endothelial function one year post op [ Time Frame: One year post-op ]
    To assess corneal endothelial function as a measurement for corneal damage sustained during grafting procedure. Endothelial function plays a role in long term corneal decompensation issues.

  6. Graft rejection rate [ Time Frame: During one-year follow up period ]
    Lamellar grafting has proven to lower graft rejection rates. Any graft rejection (endothelial, stromal or epithelial) will be recorded en reported.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • age equal or above 18 years
  • keratoconus as defined and classified by

    • presence of corneal thinning and protrusion on slit-lamp examination
    • topographic criteria according to KISA% index (>100%)
    • mean corneal curvature map
  • decreased best corrected visual acuity due to corneal scarring or contact lens intolerance

Exclusion Criteria:

  • prior corneal surgery, cross linking, refractive surgery or other treatment modalities
  • (localized) corneal thickness < 200 µm
  • associated corneal endothelial disease on specular microscopy as defined by:

    • <1500 endothelial cells per mm2
    • polymegathism > 0.3
    • pleomorphism < 0.6 (all are measurements of endothelial dysfunction)
  • gross ophthalmic pathology surpassing keratoconus as cause of decreased visual acuity
  • keratoconus-like disease (keratoglobus, pellucid marginal degeneration)
  • associated corneal anomalies (microcornea, macrocornea, buphthalmos, Peters syndrome, ICE-syndrome etc.)

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01145937

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Amphia Ziekenhuis
Breda, Netherlands, 4819 EV
Westfries Gasthuis
Hoorn, Netherlands, 1620 AR
UMCN St. Radboud
Nijmegen, Netherlands, 6500HB
Rotterdam Eye Hospital
Rotterdam, Netherlands, 3000 LM
University Medical Center Utrecht
Utrecht, Netherlands, 3508 GA
Sponsors and Collaborators
UMC Utrecht
Dr. F.P. Fischer-stichting, Utrecht, The Netherlands
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Principal Investigator: Allegonda Van der Lelij, MD PhD UMC Utrecht
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Responsible Party: R.P.L. Wisse, MD, Ophthalmologist, UMC Utrecht Identifier: NCT01145937    
Other Study ID Numbers: 30756.041.10
First Posted: June 17, 2010    Key Record Dates
Last Update Posted: December 3, 2015
Last Verified: December 2015
Keywords provided by R.P.L. Wisse, MD, UMC Utrecht:
Corneal grafting
Corneal transplantation
Anterior Lamellar Keratoplasty
Additional relevant MeSH terms:
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Corneal Diseases
Eye Diseases