Dynamic contour tonometry over silicone hydrogel contact lens

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optometry

Background:

• Accurate intraocular pressure (IOP) measurement is crucial for diagnosing and managing glaucoma.
• Silicone hydrogel contact lenses are widely used, but their effect on IOP measurements requires investigation.
• Dynamic Contour Tonometry (DCT) offers a non-contact method for IOP and ocular pulse amplitude (OPA) assessment.

Purpose of the Study:

• To compare IOP and OPA measurements using DCT with and without silicone hydrogel contact lenses of varying modulus.
• To evaluate the impact of different silicone hydrogel lens moduli on corneal biomechanics measured by Ocular Response Analyzer (ORA).
• To assess the feasibility and clinical effect of DCT over in-situ silicone hydrogel contact lenses.

Main Methods:

• Forty-seven young subjects underwent IOP, OPA, corneal hysteresis (CH), and corneal resistance factor (CRF) measurements.
• Measurements were taken without lenses and with two brands of silicone hydrogel contact lenses, with random assignment and crossover.
• DCT and ORA were utilized to assess ocular parameters and corneal biomechanics.

Main Results:

• No significant differences in CH and CRF were observed across different contact lens conditions.
• IOP measurements showed greater variability over high modulus silicone hydrogel lenses compared to no lens.
• Improved agreement for IOP measurements was noted over low modulus silicone hydrogel lenses, with OPA agreement within 1.0mmHg.

Conclusions:

• DCT is a feasible method for measuring IOP and OPA over silicone hydrogel contact lenses.
• Low modulus silicone hydrogel contact lenses do not clinically affect DCT measurements.
• The findings support the use of DCT in patients wearing low modulus silicone hydrogel contact lenses.