This chapter discusses the symptoms, examination, and diagnostic thought processes involved in evaluating a patient experiencing an alteration in visual acuity. The following terms are frequently encountered in the setting of visual acuity loss and are therefore worthy of review.
Central visual acuity: This refers to the relatively small but vital part of the visual field used for reading; it is tested with conventional eye charts and corresponds to the function of the macular area of the retina.
Marcus Gunn pupil: Also called an afferent pupillary defect, a Marcus Gunn pupil is a pupil that shows a greater consensual response than direct response to light. It is detected with the swinging penlight test described in Chapter 110.
Metamorphopsia: A subjective alteration in shape or form.
Photopsia: The sensation of sparks or flashing lights. It is usually seen in the periphery of the visual field and most often is caused by mechanical traction on the retina.
Scotoma: A focal area of visual loss in one eye.
Ocular media: The normally transparent structures of the eye including the cornea, crystalline lens, and vitreous.
Myopia. Nearsightedness.
Hyperopia. Farsightedness.
Presbyopia. The loss of ability to focus for near vision that occurs universally with increasing age. It is usually first symptomatic in the fourth and fifth decades, and usually necessitates the use of glasses for close viewing.
Copyright © 1990, Butterworth Publishers, a division of Reed Publishing.