Comparison of Goldmann applanation and dynamic contour tonometry before and after cataract surgery

PurposeTo validate changes in intraocular pressure (IOP) after phacoemulsification with intraocular lens (IOL) implantation without pressure-lowering surgery in previously unoperated eyes of normal and glaucoma patients.SettingUniversity Eye Clinic, Otto-von-Guericke-University, Magdeburg, Germany.DesignCohort study.MethodsThe IOP in both eyes of patients was determined by Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) 1 to 2 days before and after uneventful unilateral surgery. Central corneal thickness was used to correct raw GAT readings.ResultsOf the 50 patients having unilateral phacoemulsification, 29 had had cataract extraction in the contralateral eye. The mean baseline IOP was 17.4 ± 4.4 mm Hg (GAT) and 16.6 ± 2.9 mm Hg (DCT). Postoperatively, the GAT IOP decreased to 16.4 ± 6.5 mm Hg and the DCT IOP increased slightly to 17.1 ± 4.1 mm Hg. The mean tonometer difference (ΔIOP = GAT − DCT) amounted to ΔIOPpre = +0.75 ± 2.69 mm Hg in phakic eyes and ΔIOPpost = −0.70 ± 3.76 mm Hg in pseudophakic eyes (P=.0011). Consistent results were found in pairs of phakic eyes and pseudophakic eyes (mean IOP 18.0 ± 4.8 mm Hg [GAT] and 17.0 ± 3.3 mm Hg [DCT]). In fellow eyes, the mean GAT reading was 13.4 ± 4.4 mm Hg and the mean DCT value, 14.8 ± 2.4 mm Hg. ΔIOPphakic was +1.04 ± 2.75 mm Hg and ΔIOPpseudophakic was −1.48 ± 2.78 mm Hg (P=.00000021).ConclusionsThe GAT IOP readings in pseudophakic eyes seemed to be falsely low. Hence, special attention in the screening, diagnosis, and management of glaucoma is necessary.Financial DisclosureNo author has a financial or proprietary interest in any material or method mentioned.