Impact of dehydration and fasting on intraocular pressure and corneal biomechanics measured by the Ocular Response Analyzer

Abstract Background: To compare intraocular pressure (IOP) measurements by a dynamic Scheimpflug analyzer (Corvis ST), a non-contact tonometer, and the ocular response analyzer following hyperopic small-incision lenticule extraction (SMILE).Methods: Thirteen patients underwent hyperopic SMILE in one eye each were prospectively enrolled. IOP and corneal biomechanical parameters were measured preoperatively and 1 week, 1 month, and 3 months after surgery with a non-contact tonometer (IOPNCT), Corvis ST (biomechanical corrected IOP, bIOP), and the ocular response analyzer (Goldmann-correlated intraocular pressure [IOPg], cornea compensated IOP [IOPcc]). A linear mixed model was used to compare IOP and biomechanical values among the methods at each time point.Results: IOPNCT, IOPg, and IOPcc dropped significantly after surgery, with the amplitude being 3.15±0.48 mmHg, 5.49±0.94 mmHg, and 4.34±0.97 mmHg, respectively, at the last visit. IOPNCT decreased by 0.11±0.06 mmHg per µm of removed central corneal thickness. bIOP did not change significantly after surgery. Before surgery, no difference was found among the measurements (P> 0.05). After surgery, IOPNCT and bIOP were higher than IOPg and IOPcc. bIOP is independent of cornea thickness at the last visit, while correlated significantly with corneal biomechanics as other three IOP values did.Conclusion: bIOP (biomechanical corrected IOP as measured with the Corvis ST) seems to be an accurate parameter to measure IOP after hyperopic SMILE.

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Assessment of the Ocular Response Analyzer as an Instrument for Measurement of Intraocular Pressure and Corneal Biomechanics

Current Eye Research ◽

10.3109/02713683.2014.978479 ◽

2014 ◽

Vol 40 (11) ◽

pp. 1111-1119 ◽

Cited By ~ 8

Author(s):

Ahmed Elsheikh ◽

Akram Joda ◽

Ahmed Abass ◽

David Garway-Heath

Keyword(s):

Intraocular Pressure ◽

Corneal Biomechanics ◽

Ocular Response Analyzer

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Corneal Biomechanics Determination in Healthy Myopic Subjects

Journal of Ophthalmology ◽

10.1155/2016/2793516 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 9

Author(s):

Kunliang Qiu ◽

Xuehui Lu ◽

Riping Zhang ◽

Geng Wang ◽

Mingzhi Zhang

Keyword(s):

Regression Analysis ◽

Intraocular Pressure ◽

Axial Length ◽

Multivariate Regression ◽

Biomechanical Properties ◽

Corneal Biomechanics ◽

Ocular Response Analyzer ◽

Corneal Curvature ◽

Factors Associated ◽

Corneal Biomechanical Properties

Purpose. To determine the corneal biomechanical properties by using the Ocular Response Analyzer™and to investigate potential factors associated with the corneal biomechanics in healthy myopic subjects.Methods. 135 eyes from 135 healthy myopic subjects were included in this cross-sectional observational study. Cornea hysteresis (CH), corneal resistance factor (CRF), cornea-compensated intraocular pressure (IOPcc), and Goldmann-correlated intraocular pressure (IOPg) were determined with the Reichert Ocular Response Analyzer (ORA). Univariate and multivariate regression analyses were performed to investigate factors associated with corneal biomechanics.Results. The mean CH and CRF were9.82±1.34 mmHg and9.64±1.57 mmHg, respectively. In univariate regression analysis, CH was significantly correlated with axial length, refraction, central corneal thickness (CCT), and IOPg (r=-0.27, 0.23, 0.45, and 0.21, resp.; all withp≤0.015), but not with corneal curvature or age; CRF was significantly correlated with CCT and IOPg (r=0.52and 0.70, resp.; all withp<0.001), but not with axial length/refraction, corneal curvature, or age. In multivariate regression analysis, axial length, IOPcc, and CCT were found to be independently associated with CH, while CCT and IOPg were associated with CRF.Conclusions. Both CH and CRF were positively correlated with CCT. Lower CH but not CRF was associated with increasing degree of myopia. Evaluation of corneal biomechanical properties should take CCT and myopic status into consideration.

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Changes in corneal biomechanics and intraocular pressure following Femto-LASIK using Goldman applanation tonometry and ocular response analyzer

International Journal of Ophthalmology ◽

10.18240/ijo.2020.05.13 ◽

2020 ◽

Vol 13 (5) ◽

pp. 782-787

Author(s):

Ahmed Yassin Hemida

Keyword(s):

Intraocular Pressure ◽

Applanation Tonometry ◽

Corneal Biomechanics ◽

Ocular Response Analyzer

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Intraocular pressure changes and corneal biomechanics after hyperopic small-incision lenticule extraction

10.21203/rs.2.18089/v2 ◽

2020 ◽

Author(s):

Dan Fu ◽

Meiyan Li ◽

Michael C. Knorz ◽

Shengsheng Wei ◽

Jianmin Shang ◽

...

Keyword(s):

Intraocular Pressure ◽

Linear Mixed Model ◽

Corneal Thickness ◽

Corneal Biomechanics ◽

Ocular Response Analyzer ◽

Small Incision Lenticule Extraction ◽

Corvis St ◽

Small Incision ◽

Lenticule Extraction

Abstract Background: We aimed to compare the intraocular pressure (IOP) measurements by a dynamic Scheimpflug analyzer (Corvis ST), a non-contact tonometer, and an ocular response analyzer after hyperopic small-incision lenticule extraction (SMILE).Methods: Thirteen patients who underwent hyperopic SMILE in one eye were enrolled prospectively. IOP and corneal biomechanical parameters were measured preoperatively and at 1 week, 1 month, and 3 months postoperatively with a non-contact tonometer (IOPNCT), Corvis ST (biomechanical corrected IOP and biomechanical corrected IOP measured with Corvis ST [bIOP]), and an ocular response analyzer (Goldmann-correlated intraocular pressure [IOPg] and cornea compensated IOP [IOPcc]). A linear mixed model was used to compare the IOP and biomechanical values among methods at each time point.Results: IOPNCT, IOPg, and IOPcc dropped significantly after surgery, with the amplitude being 3.15±0.48 mmHg, 5.49±0.94 mmHg, and 4.34±0.97 mmHg, respectively, at the last follow-up visit. IOPNCT decreased by 0.11±0.06 mmHg per µm of excised central corneal thickness. bIOP did not change significantly after surgery. Preoperatively, no difference was found among the measurements (P> 0.05). Postoperatively, IOPNCT and bIOP were higher than IOPg and IOPcc. bIOP was independent of cornea thickness at last follow-up visit, whereas it correlated significantly with corneal biomechanics similar to the other three IOP values.Conclusion: bIOP is a relative accurate measure of IOP after hyperopic SMILE.

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