To develop and use equations of spectacle magnification
when the limiting stop is either the entrance pupil
of the eye or an artificial pupil in front of a lens.
Methods Spectacle magnification
was determined for ophthalmic lenses in air and for water
environments. The reference was the retinal image for an uncorrected eye in air with a natural pupil.
When an artificial pupil is placed in front of lenses, spectacle magnification
is hardly affected by lens power, unlike the usual situation where the natural pupil is used. The water
environment provides interesting influences in which spectacle magnification
is highly sensitive to the distance between the cornea and eye entrance pupil
. In water
, retinal images are approximately 18% bigger than in air. Wearing air-filled goggles in water
increases retinal image size by about 13% compared with that when they are not worn.
The equations extend earlier understanding of spectacle magnification
and should be useful for those wishing to determine magnification of ophthalmic lens systems when artificial pupils and environments such as water