Validity of Tono-pachymetry for Measuring Corrected Intraocular Pressure in Non-surgical and Post-photorefractive Keratectomy Eyes

다국어 초록 (Multilingual Abstract)

Purpose: To assess the validity of central corneal thickness (CCT) and corrected intraocular pressure (IOP) values
obtained by tono-pachymetry in non-surgical and post-photorefractive keratectomy (PRK) eyes.
Methods: For the study, 108 young healthy participants and 108 patients who had PRK were enrolled. Measurements
were randomly performed by tono-pachymetry, ultrasonic (US) pachymetry, and Goldmann applanation
tonometry (GAT). CCT measurement by tono-pachymetry was compared to that of US pachymetry.
The corrected IOP value obtained by tono-pachymetry was compared to that obtained by US pachymetry
and GAT. The corrected IOP from US pachymetry and GAT was calculated using the identical compensation
formula built into the tono-pachymetry. Bland-Altman plot and paired t-test were conducted to evaluate the between-
method agreements.
Results: The mean CCT measurement using tono-pachymetry was significantly greater by 7.3 μm in non-surgical
eyes (p < 0.001) and 17.8 μm in post-PRK eyes (p < 0.001) compared with US pachymetry. Differences
were significant in both Bland-Altman plotand paired t-test. The mean difference of corrected IOP values obtained
by tono-pachymetry and calculated from measurements by US pachymetry and GAT was 0.33 ± 0.87
mmHg in non-surgical eyes and 0.57 ± 1.08 mmHg in post-PRK eyes. The differences in the Bland-Altman plot
were not significant.
Conclusions: The CCT measurement determined using tono-pachymetrywas significantly thicker than that of
US pachymetry. The difference in CCT was greater in post-PRK eyes than in non-surgical eyes. However, the
corrected IOP value obtained by tono-pachymetry showed reasonable agreement with that calculated from
US pachymetry and GAT measurements.