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Cranial nerves
Published in Ian Mann, Alastair Noyce, The Finalist’s Guide to Passing the OSCE, 2021
Ideally this should be tested with a Snellen chart at six metres distance. If the patient usually wears glasses, they should keep them on. Test each eye separately, covering the other as appropriate. Invite the patient to read from the top line (largest letters) down as far as they can go. Record the findings as 6/6 if at six metres they can read down to line six, and 6/24 if at six metres they can read to line 24.
Histories and examinations in the Part 2 clinical section
Published in Joseph Manjaly, Peter Kullar, Advanced ENT Training, 2019
The patient is asked (with their visual aids on if needed) to read the lowest (smallest letters) line they can on a Snellen chart, ideally from 6 feet away if it is a 6 ft chart. The head is then rapidly perturbed in all directions (i.e. up and down and side to side) in small movements in an unpredictable manner so that the patient cannot use smooth pursuit (too rapid) or predictive saccades (too unpredictable) and the patient is asked to read down to the lowest level they can while this is being done.
Impairment of visual functions
Published in Ramar Sabapathi Vinayagam, Integrated Evaluation of Disability, 2019
The Snellen chart assesses the acuity of vision within 6 meters (20 feet). The evaluator assesses each eye separately with a pinhole occluder and current spectacles. The person reads the multi-letter, or “E,” or “C” Snellen chart with proper illumination. The line with the smallest letters that the person could read refers to a fraction, for example, 6/60 where numerator 6 denotes the test distance in meters at which the person could recognize the symbol and denominator 60 indicates the distance in meters at which the person with normal vision could recognize the symbol. The evaluator ascertains if the person could not read the largest letter on the Snellen chart at 6 m whether he/she could read at 5 m from the chart (5/60). If the person could not read the letters at 5 m, the evaluator assess whether he/she could read at 4 m (4/60), 3 m (3/60), 2 m (2/60). If the person could not read even at a 1-meter distance (1/60), the evaluator further ascertains whether he/she could count the fingers at less than one-meter distance, and, if it is not possible, whether he/she could recognize hand movement. Finally, the evaluator examines whether he/she could perceive the light splashed on his/her eye (6).
A Comparison of different scoring terminations rules for visual acuity testing: from a computer simulation to a clinical study
Published in Current Eye Research, 2019
Michael Mimouni, Reuben R. Shamir, Amir Dn. Cohen, Ran El-Yaniv, Matan J. Cohen, Leo Joskowicz, Eytan Z. Blumenthal
The ETDRS chart is accepted as being far superior to the Snellen chart owing to its more standardized design and careful choice of letter selection. Indeed, the accuracy obtained with the ETDRS chart was superior to that obtained with the Snellen chart when the per-letter and 50% termination rules were used, however, the Snellen chart was found superior when the 100% and one-miss scoring termination rules were used. The varying number of characters per row in the Snellen chart, as well as the non-uniform size increment between adjacent lines, probably explains these differences found between the two charts. Moreover, in the poor VA range, Snellen lines are significantly shorter and spaced further apart; while at the high VA range far more characters exist in each Snellen line, and subsequent lines are spaced closer together. This, in part, underlies the non-uniform accuracy found across the VA range, as demonstrated in Table 2.
Clinical Profile, Treatment, and Visual Outcome of Ocular Toxocara in a Tertiary Eye Care Centre
Published in Ocular Immunology and Inflammation, 2018
Ekta S. Sahu, Bikramjit Pal, Tarun Sharma, Jyotirmay Biswas
All patients had undergone a detailed ophthalmologic evaluation at baseline and each follow-up visit. The Snellen chart was used to measure visual acuity, which was converted to logMAR for statistical analysis. Based on the location of granuloma and intensity of inflammation, three groups were clinically categorized as: vitreous inflammation with “posterior” (between the vascular arcades), or “peripheral” (anterior to the equator) retinal granuloma, and nematode “endophthalmitis” (dense cellular infiltrate obscuring retinal granuloma and limiting retinal view).9 Associated vitreo-retinal comorbidities requiring vitreous surgery was also accounted. Data was abstracted, including demographic details, duration of disease, basis of diagnosis (clinical and laboratory), management modality, and follow-up period. Visual outcome was analyzed and correlation obtained.
The irrelevant speech effect among younger and older adults: The influence of background noises on reading comprehension
Published in Experimental Aging Research, 2018
Dana R. Murphy, Helen Bailey, Marlena Pearson, Graham Albert
All participants were also tested for visual acuity using a Snellen vision screening test. In the vision screening task, participants were required to read lines from a Snellen chart at a distance of 10 ft. Participants’ visual acuity was determined by the smallest line of type that individual was able to read correctly. The Snellen fraction associated with that line was recorded by the experimenter and used to describe the visual acuity of that individual. All vision screening was completed binocularly with corrective lenses in place when necessary. The denominator of the Snellen fraction was then used as a measure of visual acuity in subsequent analyses. The visual acuity of older adults (M = 26.47, SD = 7.93) was significantly poorer than that of younger adults (M = 20.41, SD = 4.57), t(30) = 2.69, p = .01.