Age-dependency of ocular parameters: a cross sectional study of young and elderly healthy subjects.
OBJECTIVE
To investigate the effect of aging on ocular parameters, including intraocular pressure (IOP), measured with different tonometry methods in healthy young (HY) and healthy elderly (HE) subjects and to study the effect of corneal parameters on tonometry methods.


METHODS
In this prospective, cross-sectional study, fifty eyes of 50 HY subjects (28 females, 22-31 years of age) and 43 eyes of 43 HE subjects (22 females, 64-79) were included. IOP was measured with four tonometry methods in a standardized order: ocular response analyser (ORA), dynamic contour tonometry (DCT), applanation resonance tonometry (ART) and Goldmann applanation tonometry (GAT). Other measurements included axial length (AL), central corneal thickness (CCT), corneal curvature (CC), anterior chamber volume (ACV), corneal hysteresis (CH) and corneal resistance factor (CRF).


RESULTS
The mean IOP (HY/HE; mmHg ± standard deviation (SD)) was 12.2 ± 2.2/14.1 ± 3.5 with GAT. IOP was significantly higher (difference ± standard error) in HE compared to HY measured with an ORA (+3.1 mmHg ± 0.6), GAT (+1.9 ± 0.6) and DCT (+1.6 ± 0.6). No significant difference was found in IOP measured with ART. CH and ACV were significantly lower in HE compared to HY. There was no difference between the groups in CCT, CC, AL or CRF. No tonometry method was dependant on CCT or CC.


CONCLUSIONS
IOP measured with an ORA and via DCT and GAT was higher in HE compared to HY Swedish subjects, while IOP measured with ART did not differ between the groups. In these homogeneous groups, tonometry methods were independent of CCT and CC.
Department of Clinical Science, Ophthalmology, Umeå University, SE-901 87, Umeå, SWEDEN. gauti.johannesson@umu.se.
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Jóhannesson
Department of Radiation Sciences, Umeå University, Umeå, SWEDEN.|Centre for Biomedical Engineering and Physics, Umeå University, Umeå, SWEDEN.
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Hallberg
Department of Radiation Sciences, Umeå University, Umeå, SWEDEN.|Centre for Biomedical Engineering and Physics, Umeå University, Umeå, SWEDEN.
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Ambarki
Department of Radiation Sciences, Umeå University, Umeå, SWEDEN.|Centre for Biomedical Engineering and Physics, Umeå University, Umeå, SWEDEN.
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Eklund
Department of Clinical Science, Ophthalmology, Umeå University, SE-901 87, Umeå, SWEDEN.
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Lindén
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000867:Anterior Chamber / Q000033:anatomy & histology*; D058452:Axial Length, Eye / Q000033:anatomy & histology*; D003315:Cornea / Q000033:anatomy & histology*; D063171:Corneal Pachymetry; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014065:Tonometry, Ocular; D055815:Young Adult
Age dependency; Applanation resonance tonometry; Central corneal thickness; Corneal curvature; Dynamic contour tonometry; Intraocular pressure; Ocular response analyser