Objectives: To assess the accuracy of Tonopen XL measurement of intraocular pressure (IOP) through low-power (−0.25 to −3.00) and high power (−3.25 to −6.00) silicone hydrogel lenses of 3 different materials (galyfilcon A, senofilcon A, and lotrafilcon B).
Methods: Seventy-eight patients were recruited for participation in this study. All were habitual wearers of silicone hydrogel contact lenses, and none had been diagnosed with glaucoma, ocular hypertension, or anterior surface disease. IOP was measured with and without lenses in place in the right eye only. Patients were randomized to initial measurement either with or without the lens in place. A single examiner collected all data.
Results: No statistically significant differences were noted between IOP measured without lenses and IOP measured through low-power lotrafilcon B lenses or high-power or low-power galyfilcon A and senofilcon A lenses. However, we did find a statistically significant difference between IOP measured without lenses and IOP measured through high-power lotrafilcon B lenses.
Conclusion: In general, Tonopen XL measurement of IOP through silicone hydrogel lenses may be sufficiently accurate for clinical purposes. However, Tonopen XL may overestimate IOP if performed through a silicone hydrogel lens of relatively high modulus.
Mayo Clinic (M.S., D.H.), Rochester, MN; and Bainbridge Island and Silverdale Eye Physicians (M.R.), Bainbridge Island, WA.
Address correspondence and reprint requests to Muriel Schornack, O.D., Mayo Clinic, 200 First Street SW, Rochester, MN 55905; e-mail: firstname.lastname@example.org
Supported in part by Research to Prevent Blindness, New York, NY (an unrestricted grant to the Department of Ophthalmology, Mayo Clinic, Rochester).
The authors have no conflicts of interest to declare.
Accepted March 27, 2012