Variations in corneal biomechanical Variations in corneal biomechanical

parameters and central corneal parameters and central corneal

thickness during the menstrual cycle.thickness during the menstrual cycle.

David Zadok, MD, Yakov Goldich, MD, David Zadok, MD, Yakov Goldich, MD, Yaniv Barkana, MD, Isaac Avni, MDYaniv Barkana, MD, Isaac Avni, MD

Department of OphthalmologyDepartment of Ophthalmology Assaf Harofeh Medical CenterAssaf Harofeh Medical Center

IsraelIsrael

The authors have no conflicts of interest and no financial interest in the article’s subject matter or methods mentioned.

BackgroundBackground

The cornea of women may be influenced by hormonal The cornea of women may be influenced by hormonal changes that occur during the monthly menstrual cycle.changes that occur during the monthly menstrual cycle.Cyclic variations in corneal topography and corneal Cyclic variations in corneal topography and corneal thickness have been previously described.thickness have been previously described.11

Corneal changes are probably driven by direct Corneal changes are probably driven by direct interaction of sex hormones with sex hormone receptors interaction of sex hormones with sex hormone receptors located in the human cornea.located in the human cornea.22

1. Kiely, P. M., L. G. Carney, et al. (1983). "Menstrual cycle variations of corneal topography and thickness." Am J Optom Physiol Opt 60(10): 822-9.

2. Gupta, P. D., K. Johar, Sr., et al. (2005). "Sex hormone receptors in the human eye." Surv Ophthalmol 50(3): 274-84.

BackgroundBackground The Ocular Response Analyzer (ORA; Reichert The Ocular Response Analyzer (ORA; Reichert

Inc, Buffalo, NY, USA) can be used to assess in-Inc, Buffalo, NY, USA) can be used to assess in-vivo corneal biomechanical properties, vivo corneal biomechanical properties, presented by two parameters, corneal hysteresis presented by two parameters, corneal hysteresis (CH) and corneal resistance factor (CRF).(CH) and corneal resistance factor (CRF).

These biomechanical parameters were proposed These biomechanical parameters were proposed to be used in addition to corneal thickness and to be used in addition to corneal thickness and topography for screening for corneal ectasia topography for screening for corneal ectasia before performing laser refractive procedures.before performing laser refractive procedures.33

3. Randleman, J. B. (2006). "Post-laser in-situ keratomileusis ectasia: current understanding and future directions." Curr Opin Ophthalmol 17(4): 406-12.

PurposePurpose

• The aim of our study was to The aim of our study was to evaluate whether there is a clinically evaluate whether there is a clinically meaningful variation in corneal meaningful variation in corneal biomechanical properties as biomechanical properties as measured by ORA during the measured by ORA during the menstrual cycle.menstrual cycle.

MethodsMethods

Twenty two young healthy women aged 19.5 ± 1.5 Twenty two young healthy women aged 19.5 ± 1.5 (mean ± SD) years were prospectively recruited from (mean ± SD) years were prospectively recruited from among the service staff of the Assaf Harofeh Medical among the service staff of the Assaf Harofeh Medical center.center.

Every participant was assessed at the beginning of the Every participant was assessed at the beginning of the menstrual cycle, then during ovulation, and at the end menstrual cycle, then during ovulation, and at the end of the cycle.of the cycle.

The following parameters were assessed:The following parameters were assessed: Corneal biomechanical parameters: corneal hysteresis and Corneal biomechanical parameters: corneal hysteresis and

corneal resistance factor.corneal resistance factor. Non-contact IOP with ORA: Goldmann correlated intraocular Non-contact IOP with ORA: Goldmann correlated intraocular

pressure (IOPg) and corneal compensated IOP (IOPcc). pressure (IOPg) and corneal compensated IOP (IOPcc). Central corneal thickness (CCT) with US pachymetryCentral corneal thickness (CCT) with US pachymetry

ResultsResultsTableTable . .Study parameters and their mean change and statistical significance during menstrual cycleStudy parameters and their mean change and statistical significance during menstrual cycle..

ParameterParameter

Onset of Onset of cyclecycle

OvulationOvulationEnd of End of cyclecycle

PP value value

Mean ± SDMean ± SDOnset vs Onset vs OvulatioOvulatio

nn

OvulatioOvulation vs Endn vs End

Onset vs EndOnset vs End

CCT (µm)CCT (µm) 535535 ± ± 4040 542542 ± ± 4141 543543 ± ± 4242 <<0.0010.001 0.5150.515 <<0.0010.001

CH (mmHg)CH (mmHg) 11.111.1 ± ± 1.41.4 10.110.1 ± ± 1.11.1 11.411.4 ± ± 1.81.8 <<0.0010.001 <<0.0010.001 0.0760.076

CRF (mmHg)CRF (mmHg) 10.610.6 ± ± 1.71.7 9.89.8 ± ± 1.61.6 10.510.5 ± ± 2.02.0 0.0010.001 0.0070.007 0.6730.673

IOPcc (mmHg)IOPcc (mmHg) 14.314.3 ± ± 2.72.7 15.315.3 ± ± 3.93.9 13.613.6 ± ± 2.82.8 0.1920.192 0.0650.065 0.0630.063

IOPg (mmHg)IOPg (mmHg) 14.614.6 ± ± 3.23.2 14.914.9 ± ± 4.24.2 13.913.9 ± ± 3.13.1 0.5400.540 0.0970.097 0.1400.140

CCT=central corneal thickness, CH=corneal hysteresis, CRF=corneal resistance factor, IOPcc=corneal-compensated CCT=central corneal thickness, CH=corneal hysteresis, CRF=corneal resistance factor, IOPcc=corneal-compensated intraocular pressure; IOPg=Goldmann-correlated intraocular pressureintraocular pressure; IOPg=Goldmann-correlated intraocular pressure

ResultsResults

FIGURE 1. Box and whisker plots (smallest, median and largest values with FIGURE 1. Box and whisker plots (smallest, median and largest values with interquartile range) showing corneal hysteresis at three different time points interquartile range) showing corneal hysteresis at three different time points during menstrual cycle.during menstrual cycle.

5.00

7.00

9.00

11.00

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15.00

17.00

Onset Ovulation End

Co

rne

al H

ys

tere

sis

(m

mH

g)

ResultsResults

FIGURE 2. Box and whisker plots (smallest, median and largest values with FIGURE 2. Box and whisker plots (smallest, median and largest values with interquartile range) showing corneal resistance factor at three different time interquartile range) showing corneal resistance factor at three different time points during menstrual cycle.points during menstrual cycle.

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6.00

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Onset Ovulation End

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rne

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sis

tan

ce

Fa

cto

r (m

mH

g)

ResultsResults

FIGURE 3. Box and whisker plots (smallest, median and largest values with FIGURE 3. Box and whisker plots (smallest, median and largest values with interquartile range) showing central corneal thickness at three different time interquartile range) showing central corneal thickness at three different time points during menstrual cycle.points during menstrual cycle.

400

450

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Onset Ovulation End

Ce

ntr

al C

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ea

l T

hic

kn

es

s (

µm

)

ConclusionsConclusions Corneal thickness and biomechanical parameters significantly vary Corneal thickness and biomechanical parameters significantly vary

during menstrual cycle.during menstrual cycle.

The central cornea is thinnest at the beginning and significantly thicker at The central cornea is thinnest at the beginning and significantly thicker at

ovulation and at the end of the cycle.ovulation and at the end of the cycle.

CH and CRF are statistically significantly decreased at ovulation as CH and CRF are statistically significantly decreased at ovulation as

difference between values at the beginning and the end compared with the difference between values at the beginning and the end compared with the

other two time points, with no statistically significant of the cycle. other two time points, with no statistically significant of the cycle.

Cyclical corneal alterations may need to be considered when planning Cyclical corneal alterations may need to be considered when planning

corneal refractive surgery. corneal refractive surgery.

Correspondence: David Zadok MD, E-mail: davzadok@gmail.com