Dynamic contour tonometry over silicone hydrogel contact lens.
OBJECTIVE
This study compared the measurements of intraocular pressure (IOP) and ocular pulse amplitude (OPA) using the Dynamic Contour Tonometry (DCT) over silicone hydrogel contact lenses of different modulus. Corneal biomechanics were also measured using the Ocular Response Analyzer (ORA).


METHODS
Forty-seven young (mean age 22.3 years, standard deviation 1.2 years) subjects had IOP, OPA, corneal hysteresis (CH) and corneal resistance factor (CRF) measured without lens and with two brands of silicone hydrogel contact lenses. Each eye wore one brand followed by another, randomly assigned, and then the lenses switched over. Difference and agreement of IOP and OPA with and without silicone hydrogel contact lens were studied.


RESULTS
The right and left eyes had similar corneal curvatures, central corneal thicknesses, IOP, OPA and corneal biomechanics at baseline. No significant difference was found in CH and CRF when they were measured over different contact lenses. IOP demonstrated a greater difference (95% limits of agreement: 2.73mmHg) compared with no lens when it was measured over high modulus silicone hydrogel lenses. Agreement improved over low lens modulus silicone hydrogel lenses (95% limits of agreement: 2.2-2.4mmHg). 95% limits of agreement were within 1.0mmHg for OPA.


CONCLUSIONS
This study demonstrated the feasibility of DCT over silicone hydrogel lenses. Low lens modulus silicone hydrogel contact lens in situ has no clinical effect on DCT.
School of Optometry, The Hong Kong Polytechnic University, kowloon, Hong Kong. Electronic address: sokclam@polyu.edu.hk.
Andrew K C
AK
Lam
School of Optometry, The Hong Kong Polytechnic University, kowloon, Hong Kong.
Jimmy S H
JS
Tse
D000328:Adult; D001696:Biomechanical Phenomena; D003263:Contact Lenses, Hydrophilic; D003315:Cornea / Q000502:physiology; D019781:Corneal Topography; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D020100:Hydrogels; D007429:Intraocular Pressure; D008297:Male; D012826:Silicone Elastomers; D014065:Tonometry, Ocular / Q000379:methods*; D055815:Young Adult
D020100:Hydrogels; D012826:Silicone Elastomers
Amplitud del pulso ocular; Corneal hysteresis; Corneal resistance factor; Factor de resistencia corneal; Histéresis corneal; Intraocular pressure; Lens modulus; Módulo de la lente; Ocular pulse amplitude; Presión intraocular