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Introduction to Patti Pics
For many years, pediatric eye care professionals have requested test optotypes for children that adhere to the Snellen principle of 1862 where the optotype occupies a 5 x 5 grid in which each stroke or arm is 20% of the overall height. The Sloan letter set, developed in the 1950's to the Snellen principle, has become the acuity test standard of the National Eye Institute.
Many symbol tests developed to test visual acuity in children result in acuities that are one or more lines better than Sloan/Snellen letter charts.This is particularly a problem when the child with an eye disorder or amblyopia begins to be tested with a standard clinical letter chart and acuity is reduced compared to that tested previously with symbols.
The Patti Pics optotype test has been designed to meet acuity test standardization criteria. They adhere to the Snellen principle and are calibrated to provide the same acuities as Sloan letters. Patti Pics are made up of four well-known symbols modified to provide a universal pediatric chart. The house and apple, from the New York Lighthouse symbol test, date back to the late 1960's and the Ffooks square and circle date back to the early 20th century. Patti Pics are available in all the popular formats used for many years.
Precision Vision
