Allen Figures
The classic Allen figures have been a staple for eye charts for decades. They were never made to conform to the standard 5 minutes of arc height/width or 1 minute of separation that is common with Snellen letters, therefore they are not considered true measures of standard acuity. Although it does not generally come with a response card, a card would help, especially with non-verbal persons. They are best used as a last choice to get some estimate of acuity in a child. Besides not being technically accurate, they have the appearance of looking “dated”, especially the rotary style desk phone. Many parents are astonished that a majority of kids actually identify it as a phone. This is due primarily to the continued use of the phone in even newer animated series. Additionally, this style of play phone can be purchased in any toy department.
Patti Pics – This optotype set is similar to others. However, it adds a fifth optotype, making it more reliable in clinical studies. It also uses a response card. It is included in version 10 and beyond.
Tumble E
This chart, (also sometimes referred to as a table) and its cousin, Tumble C (or broken wheel) are much more accurate than a chart of figures. This test can be done with or without a “prop”. The prop is basically the E or C on a stick handle that the child rotates to match the E or C shown on the screen. The tester will ask the child which way the hole in the wheel is pointing or the legs of the table. Alternatively, the child can use a finger to point in the direction the letter is pointing. This test is best performed using a single optotype with or without crowding bars
HOTV
This is a preferred optotype set for child testing. As with the Tumble E and C, the child (or adult with developmental or physical disabilities) does not have to know the alphabet or even speak. This chart requires a response card that has the four letters on it. The child simply plays a matching game and points to the letter on the card to match the letter on the screen. For even more accuracy, but sometimes a bit confusing for children, is the addition of “crowding bars”. This adds a bit of visual noise to make a single letter slightly more difficult to see.
Lea Symbols
These symbols were developed by a Finnish ophthalmologist in 1976. This is a symbol chart similar to the Allen Figures but is made easier due to use of a response card. It consists of four symbols, similar to HOTV. When used alongside the HOTV in the NEI VIP Children’s Vision Study it performed equally to HOTV.
Patti Pics
This chart, (also sometimes referred to as a table) and its cousin, Tumble C (or broken wheel) are much more accurate than a chart of figures. This test can be done with or without a “prop”. The prop is basically the E or C on a stick handle that the child rotates to match the E or C shown on the screen. The tester will ask the child which way the hole in the wheel is pointing or the legs of the table. Alternatively, the child can use a finger to point in the direction the letter is pointing. This test is best performed using a single optotype with or without crowding bars
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