Dagnelie Gislin, Barnett David, Humayun Mark S, Thompson Robert W
Lions Vision Research and Rehabilitation Center, Wilmer Ophthalmological Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Invest Ophthalmol Vis Sci. 2006 Mar;47(3):1241-50. doi: 10.1167/iovs.05-0157.
To investigate the feasibility of adequate reading by recipients of future prosthetic visual implants through simulation in sighted observers.
Four normally sighted subjects used a video headset to view short-story segments at a sixth grade reading level, presented in 6- to 11-word paragraphs through a pixelizing grid defined by five parameters (dot size, grid size, dot spacing, random dropout percentage, and gray-scale resolution). Grid parameters were varied individually, and four character sizes and two contrast levels were used.
Reading speeds of 30 to 60 words per minute without errors were recorded for some parameter combinations. In general, reading accuracy and speed were influenced by all parameters. Reading accuracy exceeded 90% if the following conditions were met: At least 3 dots/charwidth were presented, and dropout did not exceed 50%. Reading speed deteriorated below 20 words per minute if accuracy fell below 90% and at low contrast if the grid spanned less than two characters.
It is uncertain whether and to what extent retinal reorganization may limit the perception of multiple phosphenes by blind prosthesis recipients. If distinct phosphenes can be perceived, these results suggest that a 3 x 3-mm2 prosthesis with 16 x 16 electrodes should allow paragraph reading. The effects of stabilizing the dot grid on the retina must be investigated further.
通过在视力正常的观察者中进行模拟，研究未来假体视觉植入接受者进行充分阅读的可行性。
四名视力正常的受试者使用视频头戴设备观看六年级阅读水平的短篇小说片段，这些片段以6至11个单词的段落形式通过由五个参数（点大小、网格大小、点间距、随机丢失百分比和灰度分辨率）定义的像素化网格呈现。网格参数单独变化，并使用了四种字符大小和两种对比度水平。
对于某些参数组合，记录到每分钟30至60个单词且无错误的阅读速度。一般来说，阅读准确性和速度受所有参数影响。如果满足以下条件，阅读准确性超过90%：每个字符宽度至少呈现3个点，且丢失不超过50%。如果准确性低于90%且在低对比度下网格跨度小于两个字符，阅读速度会降至每分钟20个单词以下。
视网膜重组是否以及在何种程度上会限制盲人假体接受者对多个光幻视的感知尚不确定。如果能感知到明显的光幻视，这些结果表明，一个具有16×16个电极的3×3平方毫米的假体应该能够实现段落阅读。必须进一步研究稳定视网膜上的点网格的效果。
