The study of the effect of some factors on the human is difficult and complex because of the lack of instruments for measuring eye efficiency. The human eye is an optical organ, its work is similar to the camera work, but the eye can not return the image which it makes, but the camera can return. Producing high quality image by human optical system like other lens system is affected by many parameters, some of them are internal such as aberrations and age, pigmentation. Also human eyes suffer from some defects that effect the human eye image quality, some of these defects are: 1. Hypermetropia (Long sightedness) 2. Myopia (short sightedness) 3. Some other defects The optical characteristics of human eye imaging system are studied quantitatively via experimental and computer modeling. Experimental work is carried out to study the effect of spatial frequencies, color and ages on image eye quality. Computer simulations models are carried out to study the limitations imposed by imaging in the human eye. These limitations include the diameter of pupil eye, the aberrations (astigmatism and spherical), age, and pigmentation of eye. These limitations are computed in terms of modulation transfer function (MTF). The results showed that MTF curves are suitable for determining image quality and the limitions effect on imaging system. Also result showed a coincidence between laboratory work and theortical calculation of MTF for age, pigmentation, pupil size and aberrations.