Full-field stimulus testing: Role in the clinic and as an outcome measure in clinical trials of severe childhood retinal disease

Restoration of Cone Sensitivity to Individuals with Congenital Photoreceptor Blindness within the Phase 1/2 Sepofarsen Trial

“…At baseline, variability estimates were ±1.24 log units (95% c.i. of residuals) which was higher than previous estimates of ±0.40 log units in a larger population of subjects that included mostly those retaining better vision than LP 30 . Increased variability of vision-based perceptual measurements was expected in severely affected participants who tended to be not visual.…”

“…Sensitivity to chromatic light flashes with full-field stimulus testing (FST) was developed specifically for participants with severe vision loss and lack of oculomotor control [28][29][30][31] . FST provides a measure of best light sensitivity retained across the retina and use of chromatic stimuli allows estimation of the photoreceptor source.…”

“…In all five participants, per clinical trial protocol, chromatic FST was performed darkadapted with the commercial software using a binary thresholding algorithm and an unconstrained response-acceptance window 32,33 . In addition, chromatic FST was performed in P10 as a specialized assessment under dark-adapted and light-J o u r n a l P r e -p r o o f adapted conditions using a 4/2 dB staircase with two response reversals and a limited response-acceptance window to minimize the effect of extraneous responses not synchronized with the stimulus presentation [16][17][18]30 . The homogeneous white 10 cd.m -2 background for light-adapted FST was provided by an LED (EWL5FW12-P01, Electrospell, Anaheim, CA; CIE chromaticity coordinates: X=0.32, Y=0.33) centered on a plastic bracket fitting the Colordome (Diagnosys, Lowell, MA) filter holder.…”

Gene-Based Therapeutics for Inherited Retinal Diseases

“…This is especially true of the early-onset RCDs like LCA. To overcome this problem, clinical trials for IRDs have employed the full-field stimulus test (FST), which can evaluate visual function in patients with severe vision loss (Roman et al, 2021). FST measures the sensitivity of the entire visual field by providing an estimation of the lowest level of luminance that elicits a visual sensation by the subject.…”

“…The FST presents stimuli of varying luminance according to a prespecified algorithm and the patient presses a button when a visual sensation is perceived. The FST instrument can additionally present varying colors to preferentially test different photoreceptor subsets, or be undertaken following dark adaptation to distinguish between cone and rod deficits (Roman et al, 2021;Tuohy and Megaw, 2021).…”