Fig. 5. A. Electroretinograms recorded in 1967 for normal subject and four affected members from family with dominant retinitis pigmentosa with reduced penetrance. One to three responses to same stimulus are represented. Stimulus onset is designated by vertical hatched lines in columns 1 and 2 and vertical shock artifacts in column 3; cornea positivity is upward deflection; arrows in column 3 designate cone implicit times. Calibration symbol, lower right, designates 50 msec horizontally for columns 1 and 2 and 25 msec for column 3 and 50 μV vertically for column 1 and 100 μV vertically for columns 2 and 3. B. Electroretinograms recorded in 1977 for normal subject and four affected members from same family as in A for comparison with ERGs recorded in 1967. Calibration symbol (lower right corner) designates 60 msec horizontally and 100 μV vertically for all tracings. (From Berson EL, Simonoff EA. Dominant retinitis pigmentosa with reduced penetrance: further studies of the electroretinogram. Arch Ophthalmol 1979;97:1286.)