Abstract

An error-detecting optometer has been developed which provides high-resolution measurements of the instantaneous refractive power of the human eye. The instrument has been employed to study the dynamic and steady-state characteristics of the accommodation reflex. The error-detecting optometer utilizes a coplanar visual target and an exit slit whose position is controlled by a servomechanism. A modulated infrared beam emerges from the slit and is imaged onto the retina. A pair of lead sulfide photodetectors mounted above and below the slit are illuminated by the infrared reflected from the retina whenever the retina and the slit are not optically conjugate. The photodetectors develop a voltage whose magnitude and polarity are related directly to the degree and direction of the deviation from conjugacy. The sensitivity of the error-detecting optometer has been improved over earlier optometers by application of a null-balance technique. The optometer can be used to study open-loop accommodation responses and behavior under stabilized accommodation conditions.

© 1964 Optical Society of America

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References

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  1. G. Collins, Brit. J. Physiol. Opt. 1, 30–42 (1937).
  2. F. W. Campbell and G. Westheimer, J. Physiol. (London) 151, 285–295 (1960).
  3. J. Allen and J. H. Carter, Am. J. Optometry and Arch. Am. Acad. Optometry 37, 403–407 (1960).
    [Crossref]
  4. N. Roth, J. Optometry and Arch. Am. Acad. Optometry 39, 356–361 (1962).
    [Crossref]
  5. F. W. Campbell and J. G. Robson, J. Opt. Soc. Am. 49, 268–272 (1959).
    [Crossref] [PubMed]

1962 (1)

N. Roth, J. Optometry and Arch. Am. Acad. Optometry 39, 356–361 (1962).
[Crossref]

1960 (2)

F. W. Campbell and G. Westheimer, J. Physiol. (London) 151, 285–295 (1960).

J. Allen and J. H. Carter, Am. J. Optometry and Arch. Am. Acad. Optometry 37, 403–407 (1960).
[Crossref]

1959 (1)

1937 (1)

G. Collins, Brit. J. Physiol. Opt. 1, 30–42 (1937).

Allen, J.

J. Allen and J. H. Carter, Am. J. Optometry and Arch. Am. Acad. Optometry 37, 403–407 (1960).
[Crossref]

Campbell, F. W.

F. W. Campbell and G. Westheimer, J. Physiol. (London) 151, 285–295 (1960).

F. W. Campbell and J. G. Robson, J. Opt. Soc. Am. 49, 268–272 (1959).
[Crossref] [PubMed]

Carter, J. H.

J. Allen and J. H. Carter, Am. J. Optometry and Arch. Am. Acad. Optometry 37, 403–407 (1960).
[Crossref]

Collins, G.

G. Collins, Brit. J. Physiol. Opt. 1, 30–42 (1937).

Robson, J. G.

Roth, N.

N. Roth, J. Optometry and Arch. Am. Acad. Optometry 39, 356–361 (1962).
[Crossref]

Westheimer, G.

F. W. Campbell and G. Westheimer, J. Physiol. (London) 151, 285–295 (1960).

Am. J. Optometry and Arch. Am. Acad. Optometry (1)

J. Allen and J. H. Carter, Am. J. Optometry and Arch. Am. Acad. Optometry 37, 403–407 (1960).
[Crossref]

Brit. J. Physiol. Opt. (1)

G. Collins, Brit. J. Physiol. Opt. 1, 30–42 (1937).

J. Opt. Soc. Am. (1)

J. Optometry and Arch. Am. Acad. Optometry (1)

N. Roth, J. Optometry and Arch. Am. Acad. Optometry 39, 356–361 (1962).
[Crossref]

J. Physiol. (London) (1)

F. W. Campbell and G. Westheimer, J. Physiol. (London) 151, 285–295 (1960).

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Figures (6)

Fig. 1
Fig. 1

Equivalent optical system. (a) Conjugate state (f=f0). (b) Hypermetropic state (f>f0). (c) Myopic state (f<f0).

Fig. 2
Fig. 2

Arrangement of optical elements. (a) Light source; (b) condensing lens; (c) double aperture; (d) beam interrupter; (e) reference photocell and lamp; (f) collimating lens; (g) infrared filter; (h) viewing target; (i) exit slit and photodetectors; (j) carriage; (k) projection lens; (l) subject; (m) servomotor.

Fig. 3
Fig. 3

Servo and instrumentation flow diagram.

Fig. 4
Fig. 4

Modes of operation. (a) Nulling mode; (b) conjugate error mode; (c) open accommodation loop mode.

Fig. 5
Fig. 5

Recorded responses to accommodation stimuli. Upper trace—conjugate error; lower trace—platform position; timing mark interval—1 sec. (a) Stationary platform, 3-d step target stimulus. (b) Coupled target and platform, 1-d step chance from infinity to near.

Fig. 6
Fig. 6

Open-loop accommodation response to a 1.5-d standing error. Upper trace—conjugate error; lower trace—platform position (elicited accommodation response); timing mark interval—1 sec.