Ocular refraction with body orientation

Body inversion is used experimentally to raise the intraocular pressure (IOP). Psychophysical and electrophysiological methods of assessing visual function in artificially raised IOP are generally influenced by the clarity of the retinal image. It is therefore essential to be aware of any changes in ocular refraction induced by changes in body orientation. The present study reports on the refractive changes occurring with body orientation in conditions where accommodation is freely responding, and also immobilized pharmacologically. Ocular refraction varies by less than 0.50D across all body orientations as measured by a laser optometer which provides refractive measurements independent of the perception of blur. These results indicate that pattern-dependent tests of visual function are not likely to be influenced by refractive changes on body inversion.