Goldschmidt Mira, Déruaz Anouk, Lorincz Erika N, Whatham Andrew R, Mermoud Christophe, Safran Avinoam B
Ophthalmology Clinic, Department of Clinical Neurosciences, Geneva University Hospitals, Alcide-Jentzer 22, 1211 Geneva 14, Switzerland.
BMC Res Notes. 2010 Jan 22;3:15. doi: 10.1186/1756-0500-3-15.
Subjects with a ring scotoma can use two retinal loci, a foveal and a peripheral, for reading. Our aim was to investigate the relative use of both retinal loci as a function of the spared foveal area size and the spatial resolution at both retinal loci.
Two patients with Stargardt's disease and ring scotomas read through a scanning laser ophthalmoscope a series of letters and words at various character sizes. The number of fixations made using each retinal locus was quantified. The relative use of each retinal locus depended on character size of the stimulus. Both patients used exclusively the eccentric retinal locus to read words of large character sizes. At small character sizes, the central retinal locus was predominantly used. For reading letters or words, once foveal fixation was used, patients did not shift back to the eccentric retinal locus. When spatial resolution allowed deciphering at both the eccentric and the central areas, patients consistently fixated with the eccentric retinal locus.
Spatial resolution at the eccentric locus appears as a determinant factor to select the retinal area for reading. Reading strategies in patients with Stargardt's disease and a ring scotoma demonstrate a pattern of coordination of both eccentric and central retinal loci, reflecting a high degree of adaptation.
患有环形暗点的受试者可利用两个视网膜位点，即中央凹和周边区域进行阅读。我们的目的是研究这两个视网膜位点的相对使用情况与剩余中央凹区域大小以及两个视网膜位点的空间分辨率之间的关系。
两名患有斯塔加特病和环形暗点的患者通过扫描激光检眼镜阅读了一系列不同字号的字母和单词。对使用每个视网膜位点的注视次数进行了量化。每个视网膜位点的相对使用情况取决于刺激物的字号。两名患者在阅读大字号单词时仅使用偏心视网膜位点。在小字号时，则主要使用中央视网膜位点。对于阅读字母或单词，一旦使用了中央凹注视，患者不会再转回偏心视网膜位点。当空间分辨率允许在偏心和中央区域都能辨认时，患者始终使用偏心视网膜位点进行注视。
偏心位点的空间分辨率似乎是选择阅读视网膜区域的决定性因素。斯塔加特病和环形暗点患者的阅读策略显示出偏心和中央视网膜位点的协调模式，反映出高度的适应性。
