Ophthalmic Visual Acuity:
Ophthalmic visual acuity is the cornerstone of the ophthalmic examination. It measures central, or foveal, vision.
Vision is a complex human sense that consists of, but is not limited to, visual acuity, visual field, and contrast sensitivity.
This review will specifically address the subjective clinical measurement of visual acuity.
By definition, "the term visual acuity refers to an angular measurement relating testing distance to the minimal object size resolvable at that distance".
Simply, it is the measure of the eyes’ ability to distinguish object details and shape at a given distance.
Although visual acuity testing assesses only one aspect of visual function, it is the one test, when administered in a concise and consistent manner, which can detect changes in the integrity of the visual system.
Ophthalmic Auto Projector:
The autochart Projector is a device intended to project an image on a screen for vision testing.
Ophthalmic chart projector including a rotatable chart carrying disc and a mask plate which are co-axial with each other.
A light source and a projecting lens assembly are provided for projecting one of the charts on the disc and one of the mask openings onto a screen.
An index tube is mounted in the projecting optical path and carrying a colored filter on the inner periphery thereof.
Thus, an astigmatic index can be projected on the peripheral portion of the astigmatic examination chart.
The chart carrying disc, the mask plate and the astigmatic index tube can be controlled by knobs all provided on the front panel of the projector.