SHORT‐TERM VARIABILITY OF THE RESTING FOCUS OF ACCOMMODATION

Abstract Previous investigations have shown that, in dim illumination and empty visual fields, accommodation in most observers is for an intermediate distance referred lo as the dark focus or resting focus of accommodation. Dynamic properties of the resting focus were examined in the present study with a high‐speed infrared optometer. All subjects displayed fluctuations of accommodation in darkness that were primarily characterized by frequency components below 0.5 Hz. These fluctuations were substantially attenuated during cycloplegia or viewing a bright, high‐contrast target. Both the mean resting‐focus position and the magnitude of fluctuations varied from one subject to another and from day‐to‐day. A weak association was found between the mean and standard deviation of accommodation responses in the dark. The present findings suggest that the accommodation mechanism in most observers is somewhat unstable under degraded viewing conditions. In addition, the mean resting‐focus value for a large sample of subjects was found to be lower for i.r. optometer measurements than for previous investigations employing a laser optometer.

[1]  G. Westheimer,et al.  Fluctuations of accommodation under steady viewing conditions , 1959, The Journal of physiology.

[2]  F. Toates,et al.  Accommodation function of the human eye. , 1972, Physiological reviews.

[3]  H. Knoll,et al.  THE OPHTHALMETRON, PRINCIPLES AND OPERATION* , 1972, American journal of optometry and archives of American Academy of Optometry.

[4]  R. Hennessy,et al.  Instrument myopia. , 1975, Journal of the Optical Society of America.

[5]  D. Mershon,et al.  Stability of measures of the dark focus of accomodation. , 1980, Investigative ophthalmology & visual science.

[6]  W N Charman,et al.  Accommodation and color. , 1978, Journal of the Optical Society of America.

[7]  T. Teichmann,et al.  The Measurement of Power Spectra , 1960 .

[8]  R. J. Miller.  Mood changes and the dark focus of accommodation , 1978, Perception & psychophysics.

[9]  W N Charman,et al.  Accommodation as a Function of Object Form , 1978, American journal of optometry and physiological optics.

[10]  A. Ivanoff,et al.  Night binocular convergence and night myopia. , 1955, Journal of the Optical Society of America.

[11]  C. Johnson,et al.  Effects of luminance and stimulus distance on accommodation and visual resolution. , 1976, Journal of the Optical Society of America.

[12]  D. A. Owens.  A comparison of accommodative responsiveness and contrast sensitivity for sinusoidal gratings , 1980, Vision Research.

[13]  H. W. Leibowitz,et al.  Laser optometer incorporating the Badal principle , 1972 .

[14]  R. J. Maddock,et al.  Accommodation responses and refractive error. , 1981, Investigative ophthalmology & visual science.

[15]  D A Owens,et al.  The Mandelbaum effect: evidence for an accommodative bias toward intermediate viewing distances. , 1979, Journal of the Optical Society of America.

[16]  H W Leibowitz,et al.  Anomalous myopias and the intermediate dark focus of accommodation. , 1975, Science.

[17]  G WESTHEIMER,et al.  Accommodation measurements in empty visual fields. , 1957, Journal of the Optical Society of America.

[18]  B Winn,et al.  THE INFLUENCE OF METHOD ON THE STABILITY OF DARK FOCUS POSITION OF ACCOMMODATION , 1981, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[19]  H W Leibowitz,et al.  Night Myopia: Cause and a Possible Basis for Amelioration* , 1976, American journal of optometry and physiological optics.

[20]  P B Kruger,et al.  Infrared recording retinoscope for monitoring accomodation. , 1979, American journal of optometry and physiological optics.

[21]  W. N. Charman,et al.  Dependence of accommodation response on the spatial frequency spectrum of the observed object , 1977, Vision Research.

[22]  A. A. Skavenski,et al.  Contr of eye position in the dark. , 1970, Vision research.

[23]  F. G. Back.  Answer to N. J. Rumsey’s “Note on a Suggested Method for Evaluating Image Sharpness” , 1955 .

[24]  R. J. Miller.  Temporal Stability of the Dark Focus of Accommodation , 1978, American journal of optometry and physiological optics.

[25]  Lo J. Bour,et al.  The influence of the spatial distribution of a target on the dynamic response and fluctuations of the accommodation of the human eye , 1981, Vision Research.

[26]  M ALPERN,et al.  Effects of illuminance quantity on accommodation of the eyes. , 1958, Industrial medicine & surgery.

[27]  Miller Rj.  Temporal stability of the dark focus of accommodation. , 1978 .

[28]  H. Leibowitz,et al.  Subjective measurement of accommodation with laser light. , 1970, Journal of the Optical Society of America.

[29]  Chris A. Johnson,et al.  COMPARISON OF LASER AND INFRARED TECHNIQUES FOR MEASUREMENT OF THE RESTING FOCUS OF ACCOMMODATION: MEAN DIFFERENCES AND LONG‐TERM VARIABILITY , 1984, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[30]  G. Heath,et al.  The influence of visual acuity on accommodative responses of the eye. , 1956, American journal of optometry and archives of American Academy of Optometry.