Page 75 - PowerPoint 演示文稿

Tinted Lens 65

Fig. 7.2: Visible spectrum

Fig. 7.3: Wavelength is the distance between one wave crest to the next

of doing serious damage to the eyes, if they are of sufficient intensity. Other
radiations such as X-rays, gamma rays are also damaging to the eyes. But
since they are also damaging to the other bodily functions, they are not
treated solely as an ophthalmic problem. In addition, eye protection from
these radiations cannot be attained by absorptive lenses.

EFFECT OF RADIANT ENERGY ON THE OCULAR TISSUES
Radiation is characterized by its wavelength. The portion of the total
spectrum which is of primary ophthalmic concern is usually divided into
ultraviolet, the visible and the infrared. Other radiations such as X-ray,
gamma ray and many other forms of nuclear radiations are also damaging
to the eyes. But since they are also damaging to the other bodily functions,
they are not treated as solely an ophthalmic problem.
The visible spectrum: The media of the eye is transparent throughout the
visible spectrum which may be taken as existing between 380 nm to 780
nm. Within this region the energy is transmitted to excite the sensation of
the vision and has no harmful effects upon the tissues under the ordinary
intensities of radiation. In recent years, concern has been expressed over
the potential effects of short–wave visible radiation on ocular tissues. The
blue light hazard remains a controversial topic and, at present, it is