Download Corneal Biomechanical Properties in Mexican Population

Corneal Biomechanical
Properties in Mexican
Population
Alejandro Rivera MD
Private Practice. Mexico City.
The author has no financial interest in any of the materials described
in this poster
Purpose
The assessment of the biomechanical properties of the
cornea is important in the evaluation of patients who will
undergone refractive surgery. In the literature there is ambiguity
about the influence of age in biomechanical properties. This
study will analyze the influence of age in the biomechanical
parameters of a Mexican population.
Methods
The design was an observational series of patients without
history of ocular abnormalities. 1116 eyes of 1116 patients were
retrospectively evaluated. The data were taken from files of
patients evaluated for refractive surgery. The inclusion criteria
were patients of age 20 to 80 years, without ocular or systemic
pathology. The Ocular Response Analyzer (Reichert
Corporation, Depew, USA) was used to determine the corneal
hysteresis (CH) and the corneal resistance factor (CRF). The
results were statistically analyzed using the Analise-it for
Microsoft Excel program (Version 2.07, Analise-it Software, Ltd.
Leeds, UK).
Results
Demographic data of the 1116 eyes reported.
Histogram
Normal Fit
(Mean=36.0,
SD=10.0)
300
Frequency
250
200
150
100
50
0
20 25 30 35 40 45 50 55 60 65 70 75 80
Age
Results
No significant correlation was found between patient age
and the value of corneal hysteresis (Pearson’s correlation: r =
- 0,06, 2-tailed p: 0,0321).
20
Linear f it (9.562 -0.0103x)
18
95% CI
16
95% Prediction interval
CH
14
12
10
8
6
4
10
20
30
40
50
Age
60
70
80
Results
No significant correlation was found between patient age
and the value of corneal resistance factor (Pearson’s correlation:
r = - 0,00, 2-tailed p: 0,9235).
22
Linear f it (9.65 -0.0005045x)
20
95% CI
18
95% Prediction interval
CRF
16
14
12
10
8
6
4
10
20
30
40
50
Age
60
70
80
Conclusion
There is discrepancy about the influence of age on the
corneal biomechanical variables. Although some articles
demonstrate a negative correlation between age and corneal
resistance factor and corneal hysteresis (1,2) other studies report
the opposite (3). As shown in the results of the present study no
correlation was found between age and corneal hysteresis and
corneal resistance factor. Maybe this reflects the different
influences of age on the biomechanics of the cornea. There is an
increase in the stiffness of the corneal tissue that could be related
to the additional age-related nonenzymatic cross-linking affecting
the stromal collagen fibrils (4). On the other hand, there are agerelated changes in ultrastructural collagen fibril orientation and
dimensions that could decrease the strength of the cornea (5).
References
1.
2.
3.
4.
5.
Kamiya K, Shimizu K, Ohmoto F. Effect of aging on corneal
biomechanical parameters using the ocular response
analyzer. J Refract Surg 2009; 25: 888-893.
Kotecha A, Elsheikh A, Roberts CR, Zhu H, Garway-Heath
DF. Corneal thickness- and age-related biomechanical
properties of the cornea measured with the ocular response
analyzer. Invest Ophthalmol Vis Sci 2006; 47:5337-5347.
Kamiya K, Hagishima M, Fujimura F, Shimizu K. Factors
affecting corneal hysteresis in normal eyes. Graefes Arch Clin
Exp Ophthalmol 2008; 246: 1491-1494.
Elsheik A, Wang D, Brown M, Rama P, Campanelli M, Pye D.
Assessment of corneal biomechanical properties and their
variation with age. Curr Eye Res. 2007; 32: 11-19.
Daxer A. Age-related corneal biomechanical changes. J
Cataract Refract Surg; 2008: 34: 715.
Acknowledgment
The author is grateful to Magdalena Fabila MD for her
support in the evaluation of the data of this study.