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Lea Tests

The Lea tests are a comprehensive set of tests administered to children.  The optotypes used in this test are four shapes: a circle, square, pentagon, and apple. These symbols are easily recognizable by children and the regular geometric shapes can be described as a ring, window, or house. This way, doctors can test visual acuity without the patient knowing the Latin alphabet. Tests have shown that the Lea tests are nearly as reliable as the Landolt C test, the industry standard.

One of the most common Lea test is one that emulates the LogMAR distance vision test. Each line logarithmically decreases in size and spacing, which means the height of the letter is cut by a factor of 10 each line. The optotypes were used primarily for near vision tests because most infants do not have good distance vision anyway. The same test can be administered for distance vision when the child is a toddler. The optotypes can also be used to determine the size of the text that would be optimal to help the child read. Optotypes can be used individually on flash cards or on dominos to introduce the child to the symbols. Being able to identify these cards is important for diagnosing amblyopia.

The optotypes can be used for contrast tests as well. The test is a combination of the LogMAR and Pelli Robson charts. The optotypes decrease logarithmically in size and spacing but also their contrast decreases with each line. The child is asked to identify the shapes until the optotype is too faint to see. If the child is too young to identify shapes, the Hiding Heidi can be used. This is when a card with a face is pulled out from behind a blank page. Babies should respond to its smiling face if they are able to see it. The contrast is gradually decreases until the child no longer responds to it. 

Another test is the Lea grating acuity test. This test consists of paddle with parallel lines on them that are moved in various patterns. A child’s eyes will normally follow the direction of motion in accordance with the direction of lines. Some brain injuries or ocular aberrations may cause the lines to appear blurred or curved. If the child does not follow the motion of the paddles, it may be a sign he or she may have distorted vision.

The Panel 16 Color Test entails 16 discs of varying hues in a plastic case. The child is given a disc of the same color as one in the case and asked to select the one that looks the same. This is, obviously, done to test for colorblindness.

The next test is called the Cone Test, named after the cones of the retina being tested. The goal is to sort tiles of varying colors into a pile of like colors. If this is achieved, the room is darkened slightly until the child can no longer differentiate the colors. This test is done in order to check for night blindness-like symptoms and to judge one’s ability to adapt to changing light.