The trans-illuminated versions are identical to the original “Gold Standard” Pelli-Robson Contrast Sensitivity Charts. These charts cover ¾ of the original contrast range and are manufactured to the same true log steps and use the same letters and letter sizes as the originals.
Trans-illumination has the advantage of uniform fixed illumination and eliminates the need for staging the room and verifying chart luminance with room lighting. These charts require using our ETDRS Illuminator Cabinet™, Cat. No. 2425 and our 85 cd/m2 lamp filter, Cat No 2427D85.
Chart 5016 designated for Low Vision uses the upper 12 contrast levels ranging from 0 – 1.65 Log CS (100% – 2.2% Weber).