Safety of Repeat Intravitreal Injection of Human Retinal Progenitor Cells (jCell) in Adult Subjects With Retinitis Pigmentosa

Mean change in BCVA in study eye from baseline to month 12 as assessed by E-ETDRS. A letter score is used to compare change over time, with a higher number of letters representing better visual function, and a lower number of letters representing worse visual function. For example, 85 letters is equivalent to 20/20 visual acuity and 5 letters is equivalent to 20/800 visual acuity. A change value is derived for each subject by taking the letter score at 12 months and subtracting the letter score at baseline. A mean of all change values is then calculated.

Mean change in total kinetic visual field (KVF) area (degrees squared) of all islands of vision from baseline to 12 months. The Octopus 900 will be used for KVF testing using a specified target of V4e for subjects with a more severely impaired visual field (<10,000deg2) and a target of III4e and I4e for better seeing subjects (>10,000deg2). Target size is selected based on the Baseline visit. Whatever target size(s) is/are selected, the same size will be used throughout the study on that particular eye for that particular patient.

Contrast sensitivity (CS) measures the ability of a subject to distinguish between finer and finer increments of light versus dark (contrast), as measured with a vertical striped pattern that varies in stripe width (cycles per degree or CPD); CS thresholds are created by taking the mean of multiple trials at each size of the target (i.e., at various CPDs). A CS curve is created by using the threshold of CS means at each target size, with the highest or most sensitive value (regardless of the CPD) representing the peak of the curve (i.e., peak contrast sensitivity). The unit of measure is therefore the peak contrast sensitivity regardless of the target size (i.e., CPD) being used to perform the measurement. The higher the value, the better the ability to detect contrast. The data shown here represent the mean change from Baseline to 12 months in the subjects' peak of the CS curve.

The LLMT identifies the performance of patients as they walk along an indoor pathway of arrows and obstacles at varying lighting levels. The Critical Illumination Level (CIL) is the light level below which the patient has a markedly slower pace and more errors than all light levels above (brighter than) that point. The LLMT uses light levels that go from very dim (0.12 lux) to a bright indoor room (500 lux), with evenly spaced increments that increase light by doubling the brightness of the room from the prior level. These evenly spaced light levels have been converted to a scale score to enable easier calculation of change scores. The dimmest light level of 0 lux (completely dark room) corresponds to a scale score of 13, whereas the brightest light level of 500 lux corresponds to a scale score of 0. A positive scale score change from baseline to 12 months represents improvement in low light vision, whereas a negative scale score change represents a decline in low light vision.