Examination and discriminant analysis of corneal biomechanics with CorVis ST in keratoconus and subclinical keratoconus.
- Author:
Yuan WU
1
;
Xiao Li LI
2
;
Song Lin YANG
1
;
Xiao Ming YAN
1
;
Hai Li LI
1
Author Information
1. Department of Ophthalmology, Peking University First Hospital, Beijing 100034, China.
2. Department of Ophthalmology, Tianjin Eye Hospital, Tianjin 300020, China.
- Publication Type:Journal Article
- MeSH:
Biomechanical Phenomena;
Cornea;
Discriminant Analysis;
Humans;
Keratoconus;
Tonometry, Ocular
- From:
Journal of Peking University(Health Sciences)
2019;51(5):881-886
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVE:To compare the corneal biomechanical properties among keratoconus, subclinical keratoconus and normal corneas by using CorVis ST, and to estimate the effect of these biomechanical indices in discriminating keratoconus and subclinical keratoconus from normal.
METHODS:A total of 76 eyes of 67 subjects were enrolled and divided into three groups. Keratoconus group included 24 eyes from 17 patients, subclinical keratoconus group included 12 eyes from 12 patients and normal group included 40 normal eyes from 40 subjects．All the eyes were assessed with CorVis ST and ten biomechanical parameters, intraocular pressure (IOP) and central corneal thickness (CCT) were obtained from this machine. The discrimination of biomechanical characteristic of the three groups based on the all indices was reflected by discriminant analysis and the Fisher discriminant function was established.
RESULTS:The values of corneal biomechanics of keratoconus, subclinical keratoconus, normal eyes were increased in sequence, except for three indices: the second applamation time (A2T), time taken to reach highest concavity (HCT) and maximum corneal velocity during the first applanation (Vin). Three sets of data were among a statistically significant difference (P<0.05). There were statistically significant differences (P<0.05) between any two groups by comparing with such two indices: radius value of central concave curvature at highest concavity (HCR) and CCT. The grades of the three groups were obvious, evaluated by the discriminant function. The accuracy of reevaluation was 85% by validation method. The biggest contribution of indices in discriminant function was given by such four indices in sequence: CCT, HCR, maximum deformation amplitude of highest concavity (HCDA) and maximum corneal velocity during the second applanation (Vout).
CONCLUSION:The corneal biomechanical properties of keratoconus and subclinical keratoconus were decreased compared with normal eyes. The biomechanical parameters based on CorVis ST showed a good performance for discriminating among keratoconus, subclinical keratoconus and normal corneas.
