Techniques for objectively measuring visual acuity

Claim 3

A method as defined in claim 1 further comprising: presenting said image to said subject in the form of alternating light and dark areas.

Claim 4

A method as defined in claim 2 further comprising: presenting said alternating light and dark areas to said subject in the form of parallel, alternating light and dark stripes.

Claim 5

A method as defined in claim 1 wherein said step of progressively changing said apparent dimensional characteristics of said image comprises: reducing progressively the apparent dimensional characteristics of said oscillating image.

Claim 6

A method as defined in claim 4 wherein said image is formed on a plurality of cards, each of said cards having an image smaller in dimensions than that of its preceding card and wherein said step of reducing said dimensions of said image comprises: presenting said cards to the subject''s view individually beginning with the card having the largest dimensions of said image and thereafter substituting cards of the next smaller dimensional image.

Claim 7

A method as defined in claim 1 wherein said image is oscillated horizontally.

Claim 8

A method as defined in claim 6 wherein said image is oscillated vertically, said horizontal and vertical oscillation being performed independently of each other.

Claim 11

An apparatus as defined in claim 8 further comprising: means for monitoring the pendular eye movement of said subject.

Claim 12

An apparatus as defined in claim 9 further comprising: means for recording the eye movement of said subject.

Claim 13

An apparatus as defined in claim 8 further comprising: a housing for enclosing said target; and a window formed in said housing to enable the subject to view only the central portion of said target.

Claim 14

An apparatus as defined in claim 8 further comprising: means mounting said housing for movement between positions in which said window may be aligned selectively with either one or both of the subject''s eyes.

Claim 15

An apparatus as defined in claim 8 wherein said target comprises alternating light and dark areas.

Claim 16

An apparatus as defined in claim 13 wherein said alternating darK and light areas comprise: parallel light and dark alternating bars.

Claim 17

An apparatus as defined in claim 13 further comprising: said light and dark areas being of predetermined dimensions; and means locating said image at a predetermined distance from the subject''s eyes.

Claim 18

An apparatus as defined in claim 15 further comprising: a head rest adapted to support the subject''s head in a predetermined location.

Claim 19

An apparatus as defined in claim 8 wherein said image is formed on cards arranged in a stack, said cards in said stack having targets of different dimensions, said cards being arranged in said stack to be presented to the subject in a succession of decreasing dimensional magnitude.

Claim 20

An apparatus as defined in claim 17 further comprising: a housing; card holding means mounted in said housing for holding said stack of cards; said housing having a window formed therein to enable the facing card of said stack to be viewed by the subject; means enabling said facing card to be removed from said stack to present the next succeeding card to the subject''s view; and means mounted within said housing for illuminating said facing card.

Claim 21

An apparatus as defined in claim 16 wherein said means enabling said facing card to be removed from said stack comprises: a slot formed in said housing in registry with said card holding means; and said card holder supporting said stack of cards so that the end of each of said cards protrudes outwardly of said housing through said slot.

Claim 22

An apparatus as defined in claim 18 wherein said means mounting said target for oscillation comprises: means mounting said card holder and cards supported thereon within said housing for reciprocating movement in a lateral direction; and drive means for effecting said movement.

Claim 23

An apparatus as defined in claim 20 wherein said means for mounting said card holder within said housing comprises: a shuttle mounted within said housing for said lateral movement; means for securing said card holder to said shuttle for movement in unison therewith; and a crank drive connected to said shuttle for driving said shuttle in said lateral oscillatory motion.

Claim 24

An apparatus as defined in claim 21 wherein said housing comprises a boxlike member having top and bottom walls, sidewalls and front and rear walls, said slot being formed in said top wall and wherein said means mounting said shuttle comprises: a bracket secured within said housing between said slot and said rear wall; upper and lower roller means rotatably mounted to said bracket on the forward side thereof; said shuttle including upper and lower edges engageable with said upper and lower rollers to permit lateral oscillatory movement of said shuttle, said rollers and shuttle being effective to retain said shuttle edges in engagement with said rollers.

Claim 25

An apparatus as defined in claim 22 wherein said crank drive comprises: a motor secured to the rearward face of said bracket, said motor having an output shaft protruding forwardly through said bracket; a crank arm secured to the protruding end of said output shaft; and means connecting the end of said crank arm to said shuttle.

Claim 26

An apparatus as defined in claim 8 further comprising: a housing including front and rear walls, sidewalls, and top and bottom walls, said front wall having a window formed therein, said target being mounted within said housing in a position to be viewed through said window; a supporting surface; a pin mounted to the rearward end of the bottom wall of said housing and projecting downwardly therefrom, said pin being receivable in a hole formed in the supporting surface; a bracket secured to the bottom wall of the housing and extending downwardly therefrom, said bracket being located forwardly of said pin, said bracket including a pair of laterally spaced fingers extending downwardly therefrom at its ends, said finGers being spaced laterally a width greater than the widthwise dimension of said support and depending downwardly beyond said support whereby when said housing is disposed on said support with said pin inserted into the hole in said support, said housing may be pivoted angularly within the limits defined by engagement of the fingers on said bracket with their associated sides of said support to enable said window and target to be aligned with either or both of the subject''s eyes.

Claim 27

An apparatus as defined in claim 24 further comprising: a second bracket secured to one of said sidewalls; and a pin, secured to said sidewall rearwardly of said second bracket and projecting normally therefrom, said pin being receivable within said hole in said support whereby said housing may be reoriented on its side with said second bracket providing support for said housing.