The superior retina performs better than the inferior retina when reading with eccentric viewing: a comparison in normal volunteers.
OBJECTIVE
Patients with an absolute central scotoma, such as in age-related macular degeneration, need to use eccentric viewing for reading. In the present study, we investigated whether there are differences in reading performance between the superior and inferior retina.


METHODS
Twelve volunteers with normal vision, aged 25-58 years and able to maintain stable eccentric viewing, were studied in a scanning laser ophthalmoscope while reading a line of text, 6 degrees above or below a fixation line (series A). The text, properly magnified above threshold, was scrolled at a speed of 60 words/min. The number of words missed or incorrectly read in 1 min as well as words read when occasionally fixating the text was counted. In series B, a random letter text was superimposed upon the fixation line (i.e. at 6 degrees from the original line of text) to see whether this would disturb reading. In series C, the random letter text was moved away from the fixation line to a distance of 12 degrees from the original line of text. The entire programme was repeated in reverse order, and the mean value of the two series was used for calculations, which were carried out using Student's two-sided t-test.


RESULTS
In all series of experiments, the number of errors was significantly lower when using the superior retina compared with the inferior retina (A: p = 0.006; B: p = 0.042, C: p = 0.009). The addition of the random letter line of text at 6 or 12 degrees did not disturb reading performance significantly. There was no significant difference between the superior and inferior retina in terms of visual acuity.


CONCLUSIONS
In eccentric viewing, reading performance was significantly better when using the superior retina compared with the inferior retina. A line of random letter text at a distance of 6 or 12 degrees from the original line of text did not disturb reading significantly.
Frennesson
Christina
C
Department of Ophthalmology, Linköping University, Linköping, Sweden. Christina.Frennesson@lio.se
Nilsson
Sven Erik
SE
D000328:Adult; D006801:Humans; D008875:Middle Aged; D011932:Reading; D012016:Reference Values; D012160:Retina / Q000502:physiology*; D014792:Visual Acuity; D014794:Visual Fields