Tonopen XL assessment of intraocular pressure through silicone hydrogel contact lenses.
OBJECTIVE
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.


CONCLUSIONS
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, Rochester, MN 55905, USA. schornack.muriel@mayo.edu
Muriel
M
Schornack
Melissa
M
Rice
David
D
Hodge
D000293:Adolescent; D000328:Adult; D003263:Contact Lenses, Hydrophilic; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012828:Silicones; D014065:Tonometry, Ocular / Q000379:methods* / Q000592:standards; D055815:Young Adult
D012828:Silicones; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate