Abstract
Purpose::
To compare intraocular pressure (IOP) measurements with noncontact pneumotonometer, Goldmann applanation tonometer, and I-care tonometer in myopic eyes treated with excimer laser Photorefractive Keratectomy (PRK).
Methods::
IOP was measured with noncontact pneumotonometer, Goldmann tonometer and I-care tonometer in random order in 23 eyes before and after PRK surgery. Central corneal thickness (CCT) was measured using an ultrasonic pachymeter after all IOP determinations had been made. Right and left eyes were analyzed separately for statistical purposes.
Results::
IOP values obtained before surgery were significantly similar with all 3 instruments. After surgery, IOP values resulted significantly lower,, and appeared related to changes in CCT values. A mean decrease in IOP of 0.4 mm Hg/10 µm of CCT was observed with the pneumotonometer, a mean decraseof 0.6 mm Hg/10 µm of CCT with the Goldmann tonometer, and of 0.10 mm Hg/10 µm of CCT with the I- care tonometer.
Conclusions::
Corneal changes after myopic PRK may induce an underestimation of the IOP imeasurements. The tonometry with I-care was least affected by PRK corneal changes. Stromal thinning after refractive surgery may represent one possible factor among others. The ablation of Bowman’s layer may modify corneal elastic properties, independently from CCT.
Keywords: refractive surgery: PRK • intraocular pressure • cornea: clinical science