Effects of preferred retinal locus placement on text navigation and development of advantageous trained retinal locus.

Sixty readers were evaluated for visual function and text-navigation ability. The visual field and preferred retinal locus (PRL) were measured with a scanning laser ophthalmoscope (SLO). We found significant differences in text-navigation ability based on scotoma and PRL placement. Readers with a PRL to the left of or above a scotoma had significantly less text-navigation abilities. Readers with a PRL to the left of a scotoma tended to misread words with similar beginnings and omit the last word on a line. Readers with a PRL above a scotoma tended to skip a line or reread the same line twice. In a follow-up study, seven subjects with a nonadvantageous PRL quickly developed a trained retinal locus (TRL) during instruction with an SLO. Although the readers developed the TRL in about 15 minutes, they read slower with the TRL than the PRL. This TRL research provides promising pilot data.

Comparison of low-vision reading with spectacle-mounted magnifiers.

Reading is the most common goal among persons with age-related macular degeneration and other retinal diseases that lead to macular loss, as well as the functional task most affected by the resulting central scotomas. This project determined whether reading ability is different when persons with macular loss read with a new hybrid-diffractive spectacle magnifier versus a refractive-aspheric spectacle magnifier and an aplanatic spectacle magnifier. After subjects completed a low-vision examination, we assigned them to groups that compared different types of spectacle magnifiers and assessed their reading acuity, speed, critical print size (print size large enough to provide a subject's best fluent reading), accuracy, and comprehension. Subjects completed visual analog scales to indicate their perceptions of satisfaction with reading, comfort with reading, and cosmesis (comfort with allowing others to see them read) and were asked which of the compared spectacle magnifiers they preferred for prescription. We subjected the data to paired t-tests to ascertain whether differences existed in subjects' reading ability and perceptions between the types of reading devices. Subjects' reading comprehension, perception of satisfaction, and perception of cosmesis were significantly better with the hybrid-diffractive lens than with the refractive-aspheric lens. Although subjects' critical print size was significantly better with the aplanatic lens than with the hybrid-diffractive lens, functional reading ability was not significantly different. More subjects preferred the hybrid-diffractive lenses for prescription. The hybrid-diffractive spectacle magnifiers are an important addition to the optical-device armamentarium for reading with low vision.