Function	Recommended tests	Referral criteria	Comments
Distance visual acuity	Snellen letters, Snellen numbers, tumbling E, HOTV, picture tests (Allen figures, LEA symbols)	Fewer than four of six correct on 20-foot line (15-foot line for children six years and older) with either eye tested at 10 feet monocularly (i.e., less than 10/20 or 20/40; 10/15 or 20/30 for children six years and older) or two-line difference between eyes, even within the passing range (i.e.,10/12.5 and 10/20 or 20/25 and 20/40; 10/10 and 10/15 or 20/20 and 20/30 for children six years and older)	Tests are listed in decreasing order of cognitive difficulty; the highest test that the child is capable of performing should be used; in general, the tumbling E or the HOTV test should be used for children three to five years of age and Snellen letters or numbers for children six years and older.
			Testing distance of 10 feet is recommended for all visual acuity tests.
			A line of figures is preferred over single figures.
			The nontested eye should be covered by an occluder held by the examiner or by an adhesive occluder patch applied to the eye; the examiner must ensure that it is not possible to peek with the nontested eye.
Ocular alignment	Cross cover test at 10 feet (three meters)	Any eye movement	Child must be fixing on a target while cross cover test is performed.
	Random dot E stereo test at 40 cm	Fewer than four of six correct	Direct ophthalmoscope used to view both red reflexes simultaneously in a darkened room from two to three feet away; detects asymmetric refractive errors as well.
	Simultaneous red reflex test (Bruckner test)	Any asymmetry of pupil color, size, brightness
Ocular media clarity (e.g., cataracts, tumors)	Red reflex	White pupil, dark spots, absent reflex	Direct ophthalmoscope, darkened room. View eyes separately at 12 to 18 inches; white reflex indicates possible retinoblastoma.