May 2003
Volume 44, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2003
Improved Fixation Target for Accommodation in a Focus-detection Photoscreener
Author Affiliations & Notes
  • B.I. Gramatikov
    Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States
  • K. Tarczy-Hornoch
    Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States
  • D.S. Nassif
    Department of Ophthalmology, Children's Hospital Boston, Boston, MA, United States
  • D.G. Hunter
    Department of Ophthalmology, Children's Hospital Boston, Boston, MA, United States
  • D.L. Guyton
    Department of Ophthalmology, Children's Hospital Boston, Boston, MA, United States
  • Footnotes
    Commercial Relationships  B.I. Gramatikov, None; K. Tarczy-Hornoch, None; D.S. Nassif, None; D.G. Hunter, Johns Hopkins University P; D.L. Guyton, Johns Hopkins University P.
  • Footnotes
    Support  Research to Prevent Blindness, NIH Grant EY-12883
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 4834. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      B.I. Gramatikov, K. Tarczy-Hornoch, D.S. Nassif, D.G. Hunter, D.L. Guyton; Improved Fixation Target for Accommodation in a Focus-detection Photoscreener . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4834.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Abstract: : Purpose: Screening at a near fixation distance for uncompensated refractive error may be a better method to detect amblyopia-prone children than measurement of distance refractive error. A double-pass focus detection device using a differential bulls-eye photodetector appears useful for this purpose. But the fixation target must stimulate natural accommodation in normal subjects, a requirement not met by the original monochromatic (785 nm) point source target in our Pediatric Vision Screener. We wished to develop a fixation target eliciting more reliable accommodation. Methods: A bulls-eye photodetector, conjugate via a beam splitter to an 830 nm point light source (a Super Luminescent Diode (SLD) at a fixation distance of 40 cm), was used to assess the goodness of double-pass focus of subjects' eyes viewing monocularly. A white LED, rear-illuminating a random black-line figure, was mounted near the optical axis at a distance from the eye which compensated for the measured longitudinal chromatic aberration of the eye, such that the 830 nm point source and white LED target appeared equally clear at the same best focus for each eye tested. The white LED target subtended a visual angle of 0.6° and was displaced 6° horizontally from the direction of the 830 nm target. The goodness of focus with each color target was then determined for one eye each of 5 young adult subjects, ages 26 to 31, using added trial lenses from -5.00 D to +5.00 D on each side of the highest power plus lens that gave best subjective focus. The resulting "focus curves" were analyzed. Results: The chromatic refractive difference between the two targets measured 1.00 D for all subjects, to the nearest 0.25 D. The white LED target was therefore positioned at 28.6 cm from the eye, 1.00 D closer than the 830 nm target at 40 cm. All focus curves for each target showed some accommodation when minus lenses were added to the highest power plus lens that gave best subjective focus. Subjectively, for all subjects, accommodating to the white LED target was reported easier and more natural than accommodating to the 830 nm target. With the white LED target, areas under the focus curves were 46 % +/- 33 %(SD) larger than with the 830 nm target (p=0.022). Conclusions: A white LED "accommodative" fixation target is superior to an 830 nm SLD point source for stimulating accommodation in a focus-detection photoscreener, at least in young adults under monocular conditions at near fixation.

Keywords: screening for ambylopia and strabismus • accommodation • amblyopia 
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×