Abstract
Abstract: :
Purpose: From an ongoing study of reading strategies in eccentric fixation, we investigated, and retrospectively analyzed, the relationship between the minimum readable character size for different word lengths and for a paragraphed text, in twenty–five patients with a central scotoma and eccentric fixation. Methods: Examination was performed using a scanning laser ophthalmoscope (SLO, Rodenstock, Munich, Germany). Patients were asked to read isolated letters, two, five and ten letter–words, in eight different sizes (0.8–1.5 logMAR), presented in a random order, followed by continuous text passages in the same range of character sizes. Results: The threshold character size (TCS) could be determined for each word length in nine of the twenty–five patients. These nine patients were included in the statisctical analyses. These analyses revealed, firstly, that in these nine patients word acuity changed as a function of word length. Secondly, acuities for single letters and two–letter words were both equivalent (p=0.73), but different from acuities for five and ten–letter words and the text passages (p<0.05). Thirdly acuities for five and ten letter words were equivalent to the acuity for text passages (p= 0.76). Conclusions: The acuity for five and ten–letter words, in patients with a central scotoma and eccentric fixation, appears to be strongly predictive of the threshold character size at which a text passage can successfully be read. Measures of word acuity threshold, in such patients should be considered as being dependent on the word length used. This probably reflects an amplified occurrence of the crowding effect on long words.