The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry.
OBJECTIVE
To investigate if the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) contact lenses (CL) is affected by the positive power of the CLs.


METHODS
The experimental group comprised 26 subjects, (8 male, 18 female). IOP measurements were undertaken on the subjects' right eyes in random order using a Rebound Tonometer (ICare). The CLs had powers of +2.00D and +6.00D. Measurements were taken over each contact lens and also before and after the CLs had been worn.


RESULTS
The IOP measure obtained with both CLs was significantly lower compared to the value without CLs (t test; p<0.001) but no significant difference was found between the two powers of CLs.


CONCLUSIONS
Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses.
Degree Course in Optics and Optometry, Department of Sciences - Roma TRE University, Rome, Italy; Vision Sciences Department, Istituto Benigno Zaccagnini, Bologne, Italy; School of Life and Health Sciences, Aston University, Birmingham, UK. Electronic address: zeri@fis.uniroma3.it.
Fabrizio
F
Zeri
Degree Course in Optics and Optometry, Department of Sciences - Roma TRE University, Rome, Italy.
Mario
M
De Cusatis
Degree Course in Optics and Optometry, Department of Sciences - Roma TRE University, Rome, Italy; Vision Sciences Department, Istituto Benigno Zaccagnini, Bologne, Italy; School of Life and Health Sciences, Aston University, Birmingham, UK.
Luigi
L
Lupelli
School of Optometry, Hong Kong Polytechnic University, Hong Kong; School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia.
Peter Graham
PG
Swann
D000328:Adult; D003263:Contact Lenses, Hydrophilic; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D020100:Hydrogels; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D014065:Tonometry, Ocular / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult
D020100:Hydrogels
Contact lens; Hidrogel; Hydrogel; Intraocular pressure; Lentes de contacto; Presión intraocular; Rebound tonometry; Tonometría de rebote