DAVID GUYTON, M.D.
Medical Practice at Falls Rd, Lutherville Timonium, MD

6027216, Feb 22, 2000

Oct 15, 1998

9/172842

David Lee Guyton - Baltimore MD
David George Hunter - Baltimore MD
Saurabh Navinchandra Patel - Monmouth Junction NJ
Julie Christine Sandruck - Rochester NY
Robert Lee Fry - New Windsor MD

The Johns University School of Medicine - Baltimore MD

A61B 310

351200

Apparatus and method are provided for assessing the direction of fixation of an eye by detecting polarization-related changes in light retroreflected from the fundus of the eye. Nerve fibers in the retina of the eye are birefringent and alter the polarization state of light traversing them as a function of their orientation. The nerve fibers are arrayed in a characteristic pattern in the retina, specifically radiating outward from the fovea and converging to the optic nerve head. By assessment of polarization-related changes in rctroreflected light from multiple retinal areas either sequentially or simultaneously, characteristic birefringence signatures of portions of the retina can be identified which are used to assess the direction of fixation of the eye. In addition, interference from the corneal birefringence is reduced by using incident light having a polarization state that is substantially independent of meridional direction. Circularly polarized light or non-polarized light is used for the assessment.

4552440, Nov 12, 1985

Oct 12, 1983

6/541305

David L. Guyton - Baltimore MD

A61B 310

351214

In order to determine the visual acuity in the human eye in the presence of cataracts or other opacities, a conventional slit lamp microscope having an illumination source, an aperture illuminated thereby, and a converging lens, has been modified by the insertion of a target transparency having test figures thereon between the aperture and converging lens. The inclusion of a set of trial lenses positioned adjacent to the eye to neutralize refractive error, movement axially of the target transparency, and the inclusion of a telescopic optical system also axially adjustable is contemplated.

4367015, Jan 4, 1983

Oct 30, 1980

6/202267

Morey H. Waltuck - Worcester MA
David L. Guyton - Baltimore MD

Warner Lambert Technologies, Inc. - Southbridge MA

G02B 1308, G02B 1500

350429

In an ophthalmic refractor system for determining cylinder power and direction of axis for visual correction, cylinder axis orientation based upon corrective cylinder power in the refractor viewing path is automatically determined and introduced into the system.

2012022, Sep 13, 2012

Mar 9, 2012

13/416979

Boris I. Gramatikov - Baltimore MD, US
David L. Guyton - Baltimore MD, US
Kristina Irsch - Baltimore MD, US

The Johns Hopkins University - Baltimore MD

A61B 3/10

351215, 351221, 351246

An apparatus for detecting fixation of at least one eye of a subject on a target includes an optical illumination system, an optical detection system, and a signal processing system adapted to communicate with the optical detection system. The signal processing system is configured to calculate at least one of a time-frequency distribution or an Auto-Regressive spectral estimation of the detection signal to provide a frequency distribution of the detection signal at a plurality of times for use in determining periods in which the subject's eye is fixed on the target based on the first and second frequency signatures.

4435052, Mar 6, 1984

Oct 31, 1980

6/202521

David L. Guyton - Baltimore MD

A61B 302

351239

In apparatus for determining the refractive correction for a patient's eye, a plurality of similar test targets are presented to the patient simultaneously, with these test targets being viewed through different trial refractive corrections for the patient to choose between. Magnification differences produced by the different trial refractive corrections are compensated for by altering the size or shape of the different test targets, such that when magnified by the respective trial refractive correction, each test target appears of normal size and shape to the patient, not interfering with the patient's judgment of best clarity.