Visual Acuity The Snellen chart is used to test acuity at a distance of 6 m (20 ft). For convenience, a scale version of the Snellen chart, called the Rosenbaum card, is held at 36 cm (14 in) from the patient (Fig. 29-1). All subjects should be able to read the 6/6 m (20/20 ft) line with each eye using their refractive correction, if any. Patients who need reading glasses because of presbyopia must wear them for accurate testing with the Rosenbaum card. If 6/6 (20/20) acuity is not present in each eye, the deficiency in vision must be. | Chapter 029. Disorders of the Eye Part 2 Visual Acuity The Snellen chart is used to test acuity at a distance of 6 m 20 ft . For convenience a scale version of the Snellen chart called the Rosenbaum card is held at 36 cm 14 in from the patient Fig. 29-1 . All subjects should be able to read the 6 6 m 20 20 ft line with each eye using their refractive correction if any. Patients who need reading glasses because of presbyopia must wear them for accurate testing with the Rosenbaum card. If 6 6 20 20 acuity is not present in each eye the deficiency in vision must be explained. If worse than 6 240 20 800 acuity should be recorded in terms of counting fingers hand motions light perception or no light perception. Legal blindness is defined by the Internal Revenue Service as a best corrected acuity of 6 60 20 200 or less in the better eye or a binocular visual field subtending 20 or less. For driving the laws vary by state but most require a corrected acuity of 6 12 20 40 in at least one eye for unrestricted privileges. Patients with a homonymous hemianopia should not drive Figure 29-1 6 3 9 2 5 Gard is held in good light 14 inches from eye. Record vision for each eye separately with and without glasses. Presbyopic patients should read thru bifocal segment. Check myopes with glasses only OtiKlHCCHj TfSV J G H0SiNB UM W Lt PUPIL GAUGE mm Source Fiuci FS Kesper CL areunwald E Hauler SL Longo CL Jtmtion JL Loicelio J Wjmjon r frinsiplewf 17th Edition http Copyright S1 Thia McGrow Hill Comprriie Ing. All rights r .
