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Method of study and control of corneal biomechanical response

Supervisor: Dr. Semchishen V.A. (ILIT RAS)


Fig. 1

Fig. 2

The device for measurement of photoelasticity of transparent biological tissues was developed for determination and visualization of mechanical strength in the eye cornea. The device is a reflective polariscope Nurnberger type. Preliminary tests were held to measure the distribution of internal strength in the cornea with significant more then 3 В astigmatism before and after correction. It was demonstrated that astigmatism is not depend on anomalies of internal mechanical strength distributions.

The dependencies of biomechanical response of the eye cornea under local ablation by excimer laser radiation in paracentral zone from the thickness of cornea was studied. Changes of optical power in the centre of cornea at such treatment could be almost 10 times for thin (440 mcm) and thick (650) corneas.

The influence of different types of roughness of the stromal part of the cornea in the area of excimer laser action using LASIK (Fig.1) method for the vision corrections on the quality of retinal vision was investigated. The calculations show that under certain after surgery treatments conditions itís possible that significant part of light energy was scattered on the roughness in the zone of microkeratome and laser ablation action that decreases the vision sharpness in the low contrast and scotopic conditions.

Theoretical and experimental investigations of the speckle structure (Fig.2) that takes place under scattering of laser radiation on the retina were done. The comparison analyze of efficiency suppression of speckle modulation by various methods was presented.