ORIGINAL PAPER
Investigation of corneal biomechanics at moderate to high
refractive errors
Nehir I
˙
nceog
˘
lu
.
Sinan Emre
.
Mahmut Og
˘
uz Ulusoy
Received: 8 January 2017 / Accepted: 10 May 2017 / Published online: 24 May 2017
Ó Springer Science+Business Media Dordrecht 2017
Abstract
Purpose Corneal hysteresis (CH) and corneal resis-
tance factor (CRF) are corneal biomechanical param-
eters which were measured by ocular response analyzer
(ORA). Aim of this study was to define the CH and CRF
in high myopic and hyperopic patients and compare the
results with emmetropic control group.
Methods A total of 193 eyes of 100 healthy volun-
teers were included. Study groups were high myopic
patients (n = 27) with spherical refractive errors
(SRE) of greater than -5.00D, high hyperopic patients
(n = 20) with SRE of greater than ?3.00D and
controls (n = 53) with SRE between ± 1.00D. All
subjects underwent IOP and corneal biomechanical
evaluation with the ORA. Also Goldmann applanation
tonometry (GAT), central corneal thickness (CCT),
corneal curvature and axial length measurements were
taken.
Results Mean age of groups was 30.7 ± 6.9,
29.1 ± 7.7, 28.9 ± 5.6 years (p [ 0.05). Among
study groups except CRF and CCT, all parameters
were significantly different between study groups. CH
was lowest in the high myopic group and highest in the
high hyperopia. In all groups, there were significant
correlations between CH and CRF, CCT, SRE, SE
(spherical equivalent), AL (axial length) and between
CRF and CCT. GAT and IOPg (Goldmann-correlated
intraocular pressure) measurements were significantly
correlated with CCT (p \ 0.05). One of the major
findings was as the CH approaches 11.2 mmHg,
IOPcc (corneal-compensated intraocular pressure)
and IOPg get close to each other.
Conclusions The results revealed that CRF is not
affected by refractive errors and IOPcc is not affected
by any other ocular parameter. The difference between
IOPcc and IOPg was greatest in myopic group, and
IOP (intraocular pressure) measurement in these
patients deserves high suspicion.
Keywords Corneal biomechanics Á Corneal
hysteresis Á Corneal resistance factor Á High myopia Á
High hyperopia Á Refractive error
Introduction
Refractive errors (RE) are the major cause of mild to
moderate levels of visual impairment worldwide.
Epidemiologic studies indicate that RE are one of
N. I
˙
nceog
˘
lu
Department of Ophthalmology, Turgutlu State Hospital,
Manisa, Turkey
S. Emre
Department of Ophthalmology, School of Medicine,
Baskent University Zubeyde Hanim Hospital, Izmir,
Turkey
M. O. Ulusoy (&)
Department of Ophthalmology, School of Medicine,
Bas¸kent University Konya Research Hospital, Goz
Hastaliklari Anabilim Dali, 42000 Konya, Turkey
e-mail: drmoguz@gmail.com
123
Int Ophthalmol (2018) 38:1061–1067
https://doi.org/10.1007/s10792-017-0560-0
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