Characteristic Parameters of MTF of the Retina-Brain System.
[Objective] To search parameters characterizing the MTF curve of retina-brain system of the human eye for distinguishing eye disease use. [Method] Suppose the MTF can be expressed by (for symmetric MTF) or (for asymmetric MTF). Let y=ln(MTF), x=lnf, the above formula can be transformed into y=k<inf>1</inf>x+... (for symmetric MTF) or y=k<inf>1</inf>'x+...(for asymmetric MTF).Parameters k<inf>i</inf>s(or k<inf>i</inf>'s) are determined by curve fitting from experimental data and used as discriminating indices to indicate various eye diseases. The effectivity of the curve fitting is evaluated by F test.[Result] The fitting parameters and the peak frequencies, fc, of MTF for normal eyes and eyes with diseases are shown in table 1 with corresponding F value and F value under 0.01 confidence level. The experimental data are taken from Wang's paper for normal eyes, and Fang's paper for eyes with diseases.[Conclusion] It seems that the parameters k<inf>i</inf>s (or k<inf>i</inf>'s) can be used as the indices to distinguish eye diseases because they are remarkably different for normal and various eye diseases. In curve fitting, there are reasons to use cubic equations for symmetric MTF (as in the case of cataracts) and quadratic equation for asymmetric MTF (as in the case of amblyopia).
Bixin
Zeng
Z
Department of Physics, Wenzhou Medical, College, Zhejiang Wenzhou 325003 CHINA (e-mail: zbx@wzmc.net).
Shisu
Chen
C