Normal variations of the position of the eye in the orbit.

Photoradiographic measurements of projected corneal and nasion pituitary distances in Swedish adults and in white and black adults in the United States were transformed to true measurements. A new photographic method to compute nose-corneal distance was developed and compared to the photoradiographic and Hertel measurements. A new photographic method was developed to record interpupillary distance more accurately than earlier methods. A highly significant difference in eye position between white and black people was found. Variations in normal eye position in the same individual were studied in 39 subjects. Normal eye position was found to vary in an anterior-posterior direction, with an average variation of 1.5 to 2 mm (range, 0-3.7 mm). The interpupillary distance was found to be very stable. A difference of at least 2 mm, and perhaps 3 to 4 mm in exophthalmometric measurements is necessary to detect a pathological difference.