Corneal thickness and intraocular pressure in edematous corneas before and after Descemet stripping with automated endothelial keratoplasty.

PURPOSE

It is important to accurately measure intraocular pressure (IOP) in eyes with corneal endothelial dysfunction both before and after Descemet stripping with automated endothelial keratoplasty (DSAEK). Glaucoma is a common comorbidity in this population, and IOP elevation can worsen corneal edema. Additionally, preexisting glaucoma and steroid-responsive ocular hypertension are significant risk factors for graft rejection after DSAEK. Accurate tonometry is limited by variations in central corneal thickness (CCT) and corneal hydration that may affect corneal biomechanical properties. We analyzed CCT and IOP in eyes before and after DSAEK to determine whether changes in corneal biomechanics because of edema, grafted tissue, and subsequent stromal deturgescence affect IOP measurement.

METHODS

A retrospective chart review was performed on 32 eyes from 31 patients with corneal edema secondary to Fuchs endothelial dystrophy, bullous keratopathy, or prior graft failure, or rejection that received uncomplicated DSAEK with no evidence of persistent corneal edema or steroid-induced ocular hypertension. IOP was measured by Tono-Pen XL, and CCT was measured by ultrasound pachymetry before and approximately 3 months after surgery. We used paired t tests to evaluate changes in CCT and IOP after DSAEK and linear regression to determine the relationship between CCT and IOP before and after surgery.

RESULTS

CCT significantly decreased from 703 ± 82 to 650 ± 52 μm after DSAEK (P = 0.0026), but there was no significant change in measured IOP (16.7 ± 3.4 mm Hg preoperatively and 16.3 ± 4.1 mm Hg postoperatively; P = 0.61). There was no significant relationship between CCT and IOP before (slope = 0.10 ± 0.07 mm Hg/10 μm; r = 0.062; P = 0.17) or after (slope = 0.21 ± 0.14 mm Hg/10 μm; r = 0.072; P = 0.14) DSAEK.

CONCLUSION

CCT is significantly reduced by DSAEK but remains well above the normal range. IOP remains near the preoperative level 3 months after DSAEK. Furthermore, no correction is required for Tono-Pen measurements of IOP in corneas thickened by edema secondary to endothelial dysfunction or by DSAEK.