醫學英語(臨床醫學)（簡體書）

Light rays striking the rods and cones cause photochermical reactions of the photosensitive chemicals contained in those cells. Chemical reactions both in the rods and the cones generate electrical impulses. Impulses emitted by the rods and cones are transmitted by the optic nerves to the visual area of the occipital lobe, passing the optic chiasma, where the optic nerve fibers from the median half of each retina cross over to the optic tract on the opposite side.
EYE DISEASES
Conjunctivitis
The conjunctiva lines the outside of the eyelids, covers the anterior surface of the eye (except the cornea), and is lubricated by the tears. This warm, moist habitat can provide a suitable environment for the growth of bacteria, viruses, and other organisms, all of which may cause conjunctivitis.
Glaucoma
Glaucoma is the name given to a group of diseases that cause a particular type of optic neuropathy that results in visual field19 loss. Two major classes of glaucoma are primary open angle glaucoma (POAG) and angle closure glaucoma.
Refractive Errors22
In some eyes, rays of light from distant objects are not brought to a focus on the retina but are focused on a plane in front of the retina, as in myopia ( nearsightedness ), or behind the retina, as in hyperopia (farsightedness). Other types of refractive error include presbyopia and astigmatism. In general, refractive errors are easily corrected with glasses and are rarely accompanied by any serious disease of the eyes.
Some other eye conditions are worth mentioning: blepharitis, keratitis, scleritis,uveitis, strabismus ( squint), night blindness, color blindness, nystagmus, and agerelated macular degeneration (ARMD)
OPHTHALMOLOGICAL EXAMINATION
The most important subjective test is for visual acuity. The confrontation visual field exam is the most basic test and involves a simple assessment of peripheral vision. Other subjective examinations include color vision testing and tests of visual perception under reduced illumination. The direct and indirect ophthalmoscope has an illuminating systemthat lights up the interior of the eye and a viewing system through which the fundus can beobserved. Estimation of the intraocular pressure26 is accomplished with a tonometer.
OPTICAL AIDS
The most widely used optical aids are eyeglasses (spectacles). Most older people require an additional lens for reading, which can be incorporated with the distance correction in the form of a bifocal lens.