Elsevier

Ophthalmology

Volume 115, Issue 2, February 2008, Pages 279-286
Ophthalmology

Original article
Assessment of Eye Bank–Prepared Posterior Lamellar Corneal Tissue for Endothelial Keratoplasty

https://doi.org/10.1016/j.ophtha.2007.04.020Get rights and content

Objective

To evaluate eye bank–prepared tissue for Descemet’s stripping automated endothelial keratoplasty (DSAEK).

Design

Experimental study and retrospective case series.

Participants

Seventeen human donor corneas and 4 recipient patients undergoing DSAEK surgery.

Methods

Corneal–scleral discs were obtained. Specular microscopy and pachymetry were performed. A designated Tissue Banks International technician used a microkeratome to prepare a flap. Posterior bed thickness was measured. The sectioned tissue was stored, and at 24 and 48 hours, pachymetry was repeated. At 48 hours, specular microscopy was repeated, and endothelial cell viability was assessed with trypan blue. Descemet’s stripping automated endothelial keratoplasty was performed in 4 patients using eye bank–prepared posterior lamellar tissue.

Main Outcome Measures

Corneal tissue was assessed with the following parameters: corneal thickness measured with ultrasonic pachymetry, cell density counts measured with a keratoanalyzer, and cell viability as observed with trypan blue exclusion. Patient outcomes were measured by changes in visual acuity (VA) and the presence of a clear graft.

Results

Donor corneal pachymetry before sectioning averaged 599±52 μm. Immediately after sectioning with a microkeratome set at a depth of 300 μm, mean posterior bed thickness was 328±95 μm. Thus, the mean cutting depth achieved by the microkeratome when set at 300 micrometers averaged 271±83 μm. After storage for 24 hours, the posterior beds measured 352 μm, an average swelling of 24 (7%) μm (P = 0.14). After 48 hours, the posterior beds measured 382 μm, an average swelling of 54 (16%) μm (P = 0.02). Cell counts 48 hours after sectioning decreased by an average of 11% (P = 0.10). Endothelial cell staining confirmed improvement in postsectioning morphology and survival with increased technician experience. All 4 patients receiving eye bank–prepared DSAEK tissue showed uncomplicated postoperative results, with improvement in VA.

Conclusions

The microkeratome cutting depth was moderately accurate. Pachymetry, cell density, and cell viability of sectioned tissue after 48 hours in storage were encouraging overall. Initial clinical results of eye bank–prepared DSAEK tissue showed uncomplicated postoperative courses and improved VA. Additional studies are needed to follow the long-term outcomes in the recipients of these tissues.

Section snippets

Corneas and Grouping Protocol

Seventeen human corneal–scleral discs (Table 1) were obtained by Tissue Banks International (TBI; Baltimore, MD) after informed consent for research use was obtained from the deceased’s families. These tissues were processed entirely at the local TBI eye bank facility by TBI personnel and were not used for patient keratoplasty.

All tissues were ≤16 days postmortem. The corneas were assigned to 1 of 2 groups (Fig 1). Corneas in group 1 were used for pachymetry, which was performed at the time of

Baseline Characteristics of Donor Corneas

All of the donor corneas used for pachymetry measurements in this study were ≤7 days postmortem (group 1; Table 1), with a mean storage time of 6 days. The mean ± standard deviation (SD) age of donors in group 1 was 54±10 years. The mean ± SD precut thickness of these corneas was 599±52 μm (Table 3).

Reliability of Microkeratome Cutting Depth

In vivo microkeratome cutting depths may vary ±26 μm in one study.8Table 3 shows an average cutting depth of 271±83 μm in this study (29 μm under the target setting), reflecting a fairly consistent

Discussion

With manual dissection for traditional DSEK, the surgeon attempts to achieve a posterior lamellar thickness close to 150 μm. This is often difficult to achieve and can result in inadvertent perforation of the donor tissue’s endothelium, necessitating prompt replacement with alternative donor tissue. This event is not uncommon, particularly in the hands of inexperienced surgeons, and has often led to having a second cornea on hand in the event of this complication. The safety of having

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