Influence of corneal biomechanical properties on IOP indices in patients with keratoconus
https://doi.org/10.33791/2222-4408-2019-4-15-19
Abstract
Purpose: Evaluation of corneal biomechanical properties and their influence on IOP indices in patients with keratoconus.
Material and methods. The study included 194 eyes with keratoconus (113 patients aged from 23 to 36 years). Corneal refraction in central zone varied from 48.25 to 56.75 D, values of corneal thickness ranged from 279 to 558 pm. Patients were divided into 4 groups according to Amsler classification: I stage - 40 eyes; II stage - 78 eyes; III stage - 54 eyes and IV stage - 22 eyes. Standard ophthal-mological examination was carried out including pneumotonometry. IOP indices and values of biomechanical properties were evaluated by dynamic bidirectional pneumatic applanation and pneumatic impression.
Results. Study of corneal biomechanical properties in patients with keratoconus showed a decrease of such biomechanical indices as corneal hysteresis (CH) on average to 8.42±1.12 mm Hg, corneal resistance factor (CRF) -to 7.45±0.96 mm Hg, coefficient of elasticity (CE) - 5.35± 0.87 mm Hg. Values of these indices strongly depended on the stage of keratoconus. In the whole sample, the average corneal compensated IOP (IOPcc) amounted to 15.08± 2.43 mm Hg, Goldman IOP (IOPg) was 11.61±2.37 mm Hg and pneumatic tonometry IOP (IOPp) was 10.13±2.94 mm Hg. IOPcc indices didn't have any statistically significant difference in dependence on the stage of keratoconus (р>0.473), while in process of disease progression IOPg and IOPp indices showed statistically significant decrease of mean values.
Conclusion. Progression of keratoconus led to a decrease in corneal biomechanical properties which determine reduction of such indices as IOPg and IOPp in contrast to IOPcc.
About the Authors
I. A. Bubnova
State Research Institute of Eye Diseases
Russian Federation
Russian Federation
Med.Sc.D., Senior research scientist of Refractive Disorders Department.
11A Rossolimo St., Moscow, 119021
V. V. Averich
State Research Institute of Eye Diseases
Russian Federation
Russian Federation
M.D., Ph.D., Junior research scientist of Refractive Disorders Department.
11A Rossolimo St., Moscow, 119021
E. V. Belousova
Academy of Medical Optics and Optometry
Russian Federation
Russian Federation
M.D., Ph.D., Senior Lecturer.
63b, bld. 4 Mikhalkovskaya St., Moscow, 124438
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Review
For citations:
Bubnova I.A., Averich V.V., Belousova E.V. Influence of corneal biomechanical properties on IOP indices in patients with keratoconus. The EYE GLAZ. 2019;21(4 (128)):15-19. (In Russ.) https://doi.org/10.33791/2222-4408-2019-4-15-19
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