This near vision (40 cm / 16 inch) hand-held testing chart is two sided and features a different optotype per side.
On the first side are Patti Pics optotypes which are among the many picture-like symbols for testing children, however, Patti Pics are the only pediatric eye chart that has been designed explicitly to equal Sloan letters as used in ETDRS charts. Patti Pics are recognizable to children and help keep their attention during testing.
Side two features Sloan optotypes which were developed from the idea of Snellen optotypes. However, Sloan optotypes do not feature any serifs, making distinguishing optotypes slightly easier. Also, Sloan optotypes were chosen for their equal difficulty along with the amount of space they occupy in the Snellen 5×5 grid. Sloan letters adhere to the principles set for Snellen optotypes, but also take in new principles of total equality and difficulty.
The two islands on either side reduce memorization when testing OD, OS, and OU (Oculus Dexter, Oculus Sinister and Oculus Uterque).
Constructed with the same precision, accuracy, and methodology as traditional ETDRS charts. Lines are of equal difficulty. Geometric progression in letter size from line to line. Letter size is only variable.
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