Figure 18.

Slow emergence of a pseudo-fovea in an RPE65-LCA patient within the treated retinal region and perception of previously unseen stimuli. Panel (a) shows the eye (upper image) and the patient’s retina (lower image). Overlaid contours of constant sensitivity (measured by means of microperimetry) show no change in visual sensitivity between 1 and 12 months after treatment. F denotes the fovea, and ST the superotemporal retina that received treatment. The circular pattern is a standard grid centered on the fovea. Retinal distance calibration corresponding to 5 degrees of visual angle is shown. Panel (b) shows fixation clouds (scatter plots) in the study eye of the patient at baseline and the statistics of fixation dwell time (bar graphs) along the diagonal meridian as a function of the target luminance. All three luminances were perceived by the patient at all visits. At the 2.7- and 2.4-log₁₀ luminances, fixation was within 3 degrees of the fovea more than 99% of the time at all visits except at the 12-month visit for 2.4-log₁₀ luminance, when 68% of fixation time dwelled in an ST retinal region 4 to 9 degrees from the fovea. At 2.1-log₁₀ luminance, fixations showed increasingly greater excursions into the ST retina between 2 and 9 months after treatment. At 12 months, 89% of fixation time dwelled in the ST region 4 to 9 degrees from the fovea. Thin vertical lines represent the foveal location. Red bars indicate significant (>3 degrees) excursions from the fovea. Panel (c) shows that a dimmer target (1.8 log₁₀) was not perceived by the patient’s study eye during baseline though 9 months after treatment. At 12 months, this stimulus was perceived for the first time with a coincident shift of fixation into the ST retinal region. Reprinted from Cideciyan et al., 2009b. Copyright © 2009 Massachusetts Medical Society. All rights reserved.