Effects of Aging on Corneal Biomechanical Properties and Their Impact on 24-hour Measurement of Intraocular Pressure

Introduction: Although biomechanically corrected intraocular pressure (bIOP) is available, the effectiveness of intraocular pressure (IOP) correction in keratoconus and forme fruste keratoconus (FFK) eyes has not been investigated. Objective: Evaluation of bIOP measurements in eyes with keratoconus and FFK. Methods: Forty-two eyes in 21 patients with keratoconus in one eye and FFK in the fellow eye were examined (KC/FFK group; mean age 24.62 ± 8.6 years; 16 males and 5 females). The control group consisted of 62 eyes in 31 unaffected subjects (mean age 26.26 ± 3.64 years; 15 males and 16 females). The bIOP was determined using a Scheimpflug-based tonometer (Corvis Scheimpflug Technology [Corvis ST®]) after measuring the IOP with a conventional non-contact tonometer (NIOP). The agreement between NIOP and bIOP values was examined using the Bland-Altman plot. The difference between NIOP and bIOP (bIOP correction amount) was compared between keratoconus and FFK eyes. Results: In the control group, there were no significant differences between right and left eyes in both NIOP and bIOP values (p = 0.975 and p = 0.224, respectively). In the KC/FFK group, NIOP values were significantly lower in the keratoconus eyes (9.93 ± 1.96 mm Hg) than in the FFK eyes (12.23 ± 3.03 mm Hg; p = 0.0003). There was no significant difference in bIOP values between the right and left eyes of the KC/FFK group (p = 0.168). The bIOP correction amount was significantly increased in keratoconus eyes (3.58 ± 2.12 mm Hg) compared to in FFK eyes (1.80 ± 3.32 mm Hg; p = 0.011). Conclusions: For eyes with keratoconus and FFK, the bIOP method is effective to adjust IOP measurements based on corneal biomechanical properties.

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Intraocular Pressure–dependent Corneal Elasticity Measurement Using High-frequency Ultrasound

Ultrasonic Imaging ◽

10.1177/0161734619858386 ◽

2019 ◽

Vol 41 (5) ◽

pp. 251-270 ◽

Cited By ~ 4

Author(s):

Laurentius O. Osapoetra ◽

Dan M. Watson ◽

Stephen A. McAleavey

Keyword(s):

Intraocular Pressure ◽

High Resolution ◽

High Frequency ◽

Wave Speed ◽

Biomechanical Properties ◽

Single Element ◽

High Frequency Ultrasound ◽

Spatially Resolved ◽

Corneal Biomechanical Properties ◽

Frequency Ultrasound

Measurement of corneal biomechanical properties can aid in predicting corneal responses to diseases and surgeries. For delineation of spatially resolved distribution of corneal elasticity, high-resolution elastography system is required. In this study, we demonstrate a high-resolution elastography system using high-frequency ultrasound for ex-vivo measurement of intraocular pressure (IOP)-dependent corneal wave speed. Tone bursts of 500 Hz vibrations were generated on the corneal surface using an electromagnetic shaker. A 35-MHz single-element transducer was used to track the resulting anti-symmetrical Lamb wave in the cornea. We acquired spatially resolved wave speed images of the cornea at IOPs of 7, 11, 15, 18, 22, and 29 mmHg. The IOP dependence of corneal wave speed is apparent from these images. Statistical analysis of measured wave speed as a function of IOP revealed a linear relation between wave speed and IOP cs = 0.37 + 0.22 × IOP, with the coefficient of determination R2 = 0.86. We also observed depth-dependent variations of wave speed in the cornea, decreasing from anterior toward posterior. This depth dependence is more pronounced at higher IOP values. This study demonstrates the potential of high-frequency ultrasound elastography in the characterization of spatially resolved corneal biomechanical properties.

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Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument

Journal of Biomedical Optics ◽

10.1117/1.jbo.22.2.020502 ◽

2017 ◽

Vol 22 (02) ◽

pp. 1 ◽

Cited By ~ 4

Author(s):

Manmohan Singh ◽

Zhaolong Han ◽

Achuth Nair ◽

Alexander Schill ◽

Michael D. Twa ◽

...

Keyword(s):

Intraocular Pressure ◽

Biomechanical Properties ◽

Optical Coherence ◽

Noncontact Measurement ◽

Single Instrument ◽

Corneal Biomechanical Properties

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Corneal Biomechanical Assessment Using Corneal Visualization Scheimpflug Technology in Keratoconic and Normal Eyes

Journal of Ophthalmology ◽

10.1155/2014/147516 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 46

Author(s):

Lei Tian ◽

Yi-Fei Huang ◽

Li-Qiang Wang ◽

Hua Bai ◽

Qun Wang ◽

...

Keyword(s):

Intraocular Pressure ◽

Corneal Thickness ◽

Area Under The Curve ◽

Biomechanical Properties ◽

Corvis St ◽

Biomechanical Assessment ◽

Deformation Amplitude ◽

Biomechanical Parameters ◽

And Control ◽

Corneal Biomechanical Properties

Purpose. To compare the corneal biomechanical properties of keratoconic patients and age-matched controls using corneal visualization Scheimpflug technology (Corvis ST).Methods. Sixty keratoconic eyes from 47 keratoconus patients and 60 normal eyes from 60 controls were enrolled in this prospective study. Tomography and biomechanical parameters of all eyes were obtained with the Pentacam and Corvis ST, respectively. Intraocular pressure was measured using a Goldmann applanation tonometer.Results.The tomography and biomechanical parameters of the keratoconic corneas were significantly different from those of the normal corneas except for the anterior chamber angle, first applanation length, the highest concavity time, and peak distance. The deformation amplitude was the best predictive parameter (area under the curve: 0.882), with a sensitivity of 81.7%, although there was a significant overlap between keratoconic and normal corneas that ranged from 1.0 to 1.4 mm. In both the keratoconus and control groups, the deformation amplitude was negatively correlated with intraocular pressure, central corneal thickness, and corneal volume at 3 and 5 mm.Conclusions. Corvis ST offers an alternative method for measuring corneal biomechanical properties. The possibility of classifying keratoconus based on deformation amplitude deserves clinical attention.

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The Effect of Dehydration and Fasting on Corneal Biomechanical Properties and Intraocular Pressure

Eye & Contact Lens Science & Clinical Practice ◽

10.1097/icl.0000000000000220 ◽

2016 ◽

Vol 42 (6) ◽

pp. 392-394 ◽

Cited By ~ 6

Author(s):

Refik Oltulu ◽

Gunhal Satirtav ◽

Ismail Ersan ◽

Erkan Soylu ◽

Mehmet Okka ◽

...

Keyword(s):

Intraocular Pressure ◽

Biomechanical Properties ◽

Corneal Biomechanical Properties

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Characterization of Corneal Biomechanical Properties and Determination of Natural Intraocular Pressure Using CID-GAT

Translational Vision Science & Technology ◽

10.1167/tvst.8.5.10 ◽

2019 ◽

Vol 8 (5) ◽

pp. 10 ◽

Cited By ~ 1

Author(s):

Shu-Hao Lu ◽

I. T. Chong ◽

Stanley Y. Y. Leung ◽

David C. C. Lam

Keyword(s):

Intraocular Pressure ◽

Biomechanical Properties ◽

Corneal Biomechanical Properties

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Intraocular pressure measurements and corneal biomechanical properties using a dynamic Scheimpflug analyzer, after several keratoplasty techniques, versus normal eyes

Journal Français d Ophtalmologie ◽

10.1016/j.jfo.2017.06.006 ◽

2018 ◽

Vol 41 (1) ◽

pp. 30-38 ◽

Cited By ~ 4

Author(s):

J. Hugo ◽

E. Granget ◽

G. Ho Wang Yin ◽

M. Sampo ◽

L. Hoffart

Keyword(s):

Intraocular Pressure ◽

Biomechanical Properties ◽

Pressure Measurements ◽

Corneal Biomechanical Properties

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Ocular Response Analyser — a New Diagnostic Tool to Measure Corneal Biomechanical Properties and Intraocular Pressure

Asian Journal of Ophthalmology ◽

10.35119/asjoo.v12i3.306 ◽

1970 ◽

Vol 12 (3) ◽

pp. 159-168

Author(s):

Arulmozhi Varman ◽

Muthuraman Chockalingam

Keyword(s):

Intraocular Pressure ◽

Diagnostic Tool ◽

Pressure Measurement ◽

Corneal Thickness ◽

Biomechanical Properties ◽

Ocular Diseases ◽

Wide Range ◽

Corneal Biomechanical Properties ◽

Ocular Response Analyser

Corneal biomechanical properties have been known to influence the outcome of ocular measurements and procedures for a wide range of ocular diseases. The assessment of corneal biomechanical properties has been a challenge and, for this reason, measurement of the geographical parameters of the cornea, namely corneal thickness and topography, has formed the mainstay of understanding the basis of various ocular pathologies. A newly marketed instrument, the Reichert ocular response analyser has been developed to improve the accuracy of intraocular pressure measurement by uniquely measuring and integrating corneal biomechanical data into its intraocular pressure estimates.

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