Central corneal thickness and tonometric intraocular pressure in healthy young Malaysian Chinese adults
Medical hypothesis, discovery & innovation in optometry,
Vol. 7 No. 3 (2026),
31 October 2026
,
Page 154-163
https://doi.org/10.51329/mehdioptometry256
Abstract
Background: Central corneal thickness (CCT) can influence intraocular pressure (IOP) readings, but the relationship varies across tonometers and populations. This study examined the associations between CCT and uncorrected IOP measured using Canon TX-F non-contact tonometry (NCT) and AccuPen contact applanation tonometry in healthy young Malaysian Chinese adults.Methods: This cross-sectional comparative study was conducted at UCSI University, Kuala Lumpur, Malaysia, between July and October 2019. Participants aged 18–25 years were recruited through voluntary, non-probability sampling. Eligibility required best-corrected visual acuity of 6/6 or better in each eye and clinically healthy anterior segments and optic nerve heads. A single optometrist performed bilateral examinations between 12:00 and 17:00 in a fixed sequence: NCT, ultrasonic pachymetry using AccuPach VI, and AccuPen tonometry. Three valid measurements per eye were averaged for each instrument. IOP readings were analysed without CCT correction.
Results: Of 98 individuals screened, 84 were enrolled, including 30 (35.7%) men and 54 (64.3%) women. Mean (standard deviation [SD]) age was 21.61 (1.88) years, and mean (SD) CCT was 570.11 (36.50) µm. Mean (SD) IOP was 15.50 (2.13) mmHg with NCT and 13.00 (2.35) mmHg with AccuPen. NCT readings were higher by a mean paired difference of 2.50 mmHg (95% confidence interval [CI], 2.11–2.89; P < 0.001). CCT was positively correlated with NCT readings (r = 0.339; 95% CI, 0.134–0.516; P < 0.05) and AccuPen readings (r = 0.310; 95% CI, 0.103–0.491; P < 0.05). CCT accounted for 11.5% and 9.6% of the variance in NCT and AccuPen readings, respectively. The regression slopes were numerically similar, corresponding to approximately 0.20 mmHg higher measured IOP per 10-µm greater CCT.
Conclusions: Greater CCT was associated with higher uncorrected IOP readings from both tonometers, while NCT yielded higher mean readings. These findings support considering CCT and instrument type when interpreting IOP in this population, without establishing device interchangeability or equivalent CCT sensitivity. Future studies in larger, more representative samples should examine how closely IOP readings from Canon TX-F NCT and AccuPen agree and how consistent repeated measurements are with each device.
- corneal pachymetry
- intraocular pressure
- tonometry
- ocular
- young adult
- cross-sectional studies
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