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D. T. Chang, M. B. Pantcheva, R. J. Noecker; Corneal Thickness and Intraocular Pressure in Edematous Corneas Before and After Descemet’S Stripping With Automated Endothelial Keratoplasty. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1475.
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Accurate measurement of intraocular pressure (IOP) is important in eyes with corneal endothelial dysfunction both before and after Descemet’s stripping with automated endothelial keratoplasty (DSAEK). Glaucoma is a common comorbidity in this population and IOP elevation can worsen corneal edema, while pre-existing 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 due to edema, grafted tissue and subsequent stromal deturgescence affect IOP measurements.
A retrospective chart review was performed on 32 eyes from 31 patients with corneal edema secondary to Fuch’s endothelial dystrophy, bullous keratopathy or prior graft failure 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 three months after surgery. Paired t-tests were used to evaluate changes in CCT and IOP after DSAEK, and linear regression was used to analyze the relationship between CCT and IOP.
CCT significantly decreased from 703 ± 82 µm to 650 ± 52 µm after DSAEK (p = 0.0026), but there was no significant change in IOP (16.7 ± 3.4 mm Hg preoperatively, 16.3 ± 4.1 mm Hg postoperatively; p = 0.61). There was also no significant relationship between CCT and IOP before (slope = 0.10 ± 0.07 mm Hg/10 µm; r2 = 0.062; p = 0.17) or after (slope = 0.21 ± 0.14 mm Hg/10 µm; r2 = 0.072; p = 0.14) DSAEK.
CCT is significantly reduced by DSAEK but remains well above the normal range. IOP remains at the preoperative level three 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.
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