THIS PARAGRAPH HAS BEEN WRITTEN IN REFERENCE TO MDU ROHTAK EXAM PATTERN
In order to ensure a person’s optic nerves are healthy, optometrists check the pressure placed on them by the fluid in the eyes. This pressure is called intraocular pressure and should measure between 10 mmHg and 21 mmHg. Measurements that are higher than normal can be a sign of early glaucoma or retinal detachment.
This diagram is from the copyright-free collection, The Sourcebook of Medical Illustration, edited by Peter Cull (Park Ridge, NJ: Parthenon, 1989).
Epidermis: outermost layer, mostly dead keratinized cells (stratified squamous epithelium). No blood vessels, gets nutrition from dermis. Dead cells slough off and are replaced by dividing cells in the stratum basale. Half life of skin cells about 35 days.
Dermis: contains blood vessels, nerves, sensory receptors for touch, pressure, hot, cold, pain. Also has hair follicles and sweat glands. All this is imbedded in fibrous connective tissue.
The traditional Snellen chart is printed with eleven lines of block letters. The first line consists of one very large letter, which may be one of several letters, for example E, H, N, or A. Subsequent rows have increasing numbers of letters that decrease in size. A patient taking the test covers one eye, and reads aloud the letters of each row, beginning at the top. The smallest row that can be read accurately indicates the patient’s visual acuity in that eye.
