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"Exposing the truth to wipe out animal experimentation"

Government Grants Promoting Cruelty to Animals

Washington University, St. Louis, MO

Lawrence Tychsen - Grant Application - 2002

Grant Number: 2 R01 EY010214-08
Project Title: Early Functional-Structural Repair of Macaque Strabismus
PI Information: PROFESSOR LAWRENCE TYCHSEN, M.D.  tourville@vision.wustl.edu 
Phone: 314-362-3743 Fax: 314-362-3131

Trans Am Ophthalmol Soc. 2007 December; 105: 564–593.
PMCID: PMC2258131
Copyright ©American Ophthalmological Society 2007

CAUSING AND CURING INFANTILE ESOTROPIA IN PRIMATES: THE ROLE OF DECORRELATED BINOCULAR INPUT (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)

Lawrence Tychsen, MD

From the Departments of Ophthalmology and Visual Sciences, Pediatrics, Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri

ANIMALS AND GOGGLE REARING GROUPS

Monkeys (Macaca mulatta) born at the Yerkes Primate Center in Atlanta, Georgia, were fitted with goggles on the first day of life (Figure 1). The fitting procedure was an adaptation of that originally described by Crawford.27,28 The procedure was not stressful to the newborn macaques and did not require anesthesia or fabrication of a head mold. Padded head straps held the goggles firmly in place and prevented the infant from removing the apparatus, which was custom-fabricated for each monkey from lightweight plastic. The front piece consisted of 2 lens holders, which unscrewed so that ultra-lightweight, 2-mm-thick Fresnel plastic prisms could be inserted. Animals were observed several times per day in the primate nursery and during bottle feedings to ensure that the goggles remained clear and in proper position. The goggles did not interfere noticeably with normal play or mingling with other infant macaques. The goggle helmet was removed from each monkey for cleaning a minimum of once per day. During cleaning and, if necessary, adjustment of the goggle, the animal was placed briefly in a dark (light-tight) enclosure to preclude normal binocular experience. Inspections of the infant monkeys during these brief periods when the goggles were removed for cleaning disclosed that, after several weeks, each of the animals manifested esotropia.

A total of 8 monkeys were studied: 6 experimental and 2 controls. The 6 experimental monkeys (Table 1) were divided into 3 prism-rearing groups: 3-week (2 animals), 12-week (1 animal), and 24-week (3 animals) groups. In each group, experimental animals wore prism goggles (for periods of 3 to 24 weeks) to impose horizontal and vertical binocular noncorrespondence (decorrelation) of 11.4º (20 prism diopters) in each eye; 11.4º base-in in one eye, and 11.4º base-down in the other eye. The 2 controls wore goggles with plano lenses. At 4 to 6 months of age, the monkeys were shipped to Washington University in St Louis, Missouri, where they were trained to perform visual fixation and tracking tasks without goggles, using a positive-feedback reward (a small bolus of fruit juice).29 Cycloplegic refractions revealed a refractive error ≤ +3.00 spherical equivalent in each of the experimental and control animals.

At age 1 year, eye coils were implanted29 and ocular motor as well as sensory testing initiated, which proceeded typically for 3 to 6 months. Monocular visual acuity was measured using spatial sweep visual evoked potentials (SSVEP)30,31 (without correction for refractive error).

EYE MOVEMENT RECORDINGS

Detailed descriptions of the surgical and recording methods have been published in previous reports, and for this reason only, an abbreviated description is provided here.29,32 Using deep general inhalation anesthesia (supplemented by local infiltration and topical anesthesia), scleral search coils were implanted in both eyes and a custom-built, polycarbonate head-restraint device was attached to the skull. All procedures were performed in compliance with the ARVO resolution on the use of animals in research and were approved by the Washington University Animal Care and Use Committee.

Eye movements were recorded using standard magnetic search coil techniques.33,34 The monkey sat in a primate chair in the middle of field coils. The head restraint was locked to preclude head movement and the room was lit with dim background illumination. Eye position was calibrated at the start of each recording session by using a calibration coil and by having the animal maintain eye position within a 2º window of target position. The target was a laser spot subtending ~ 0.05º projected onto the back of a translucent screen located 50 cm in front of the animal. The calibration sequence was repeated separately for each eye.

Recordings were performed under conditions of binocular and monocular viewing. Monocular viewing was achieved by use of liquid-crystal shutter goggles which cycled from transparent to opaque (or the reverse) in 80 microseconds (0.08 msec).35 Voltages proportional to horizontal and vertical eye position were digitized at 500 Hz. Eye velocity signals were obtained by passing the eye position signals through a Finite Impulse Response filter (DC to 90 Hz) and differentiated. Angular resolution of the system was about 0.05º. Experiments were controlled and the data were acquired and analyzed with the aid of a computer and interactive signal processing software (Spike2 for Macintosh, Cambridge Electronic Design, United Kingdom, and Igor Graphics, Wave Metrics, Lake Oswego, Oregon).

VISUAL STIMULI AND TRIAL DESIGN
Eye Alignment

In the months before coil implantation, eye alignment was assessed using 35 mm photographs and video recordings of each monkey (Hirshberg method36,37). After implantation of eye coils, alignment was measured under conditions of binocular viewing to document precisely the magnitude of any intermittent or constant heterotropia. The fixation target was displaced from primary position (straight ahead) to the cardinal positions of gaze to assess concomitance of any misalignment. Alignment during periods of binocular viewing was compared with alignment when viewing with either eye covered, to reveal the presence of any heterophoria (horizontal or vertical).

Stable Fixation

Viewing monocularly, each monkey was required to fixate the laser spot at straight-ahead gaze or at eccentricities of ± 10º horizontally and vertically (Figure 2). The target was presented in repeated trials. In order to receive a juice reward, the animal had to maintain eye position of the nonoccluded, fixating eye within a 2º fixation window, surrounding the target, for a randomized interval of 2 to 5 sec. The small target size, variability of target location, small fixation window, and random duration of required fixation ensured a high level of visual attention.29

Smooth Pursuit

Smooth pursuit was recorded under conditions of monocular viewing using a modification of the “step-ramp” paradigm of Rashbass (Figure 2).38,39 At the beginning of each trial, the animal fixated on the stationary spot at straight-ahead gaze. When the animal’s eye remained within a 2º window continuously for an interval of 2 to 5 sec, the stationary spot disappeared and a second spot appeared, moving rightward or leftward at 30º/sec. The moving spot started either from the point of fixation (zero eccentricity) or from 1 of 8 other initial positions along the horizontal meridian (5º and 10º above, below, to the right and left of zero eccentricity). The “step-ramp” approach allowed presentation of target motion at a precise location on the retina as determined by the relative positions of the stationary and moving spots. When viewing with the left eye, rightward target velocities represented nasally directed motion, and leftward target velocities temporally directed stimulus motion in the visual field. To receive the juice reward, the monkey had to track the stimulus within the 2º window for a duration > 750 msec. The onset, direction (up, down, left, right), and speed of the target were controlled by the computer program, which selected combinations of initial target position and direction in a pseudorandom fashion to preclude prediction.

Please email:  LAWRENCE TYCHSEN, M.D. tourville@vision.wustl.edu or
Phone: 314-362-3743 Fax: 314-362-3131 to protest the inhumane use of animals in this experiment. We would also love to know about your efforts with this cause: saen@saenonline.org

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Rats, mice, birds, amphibians and other animals have been excluded from coverage by the Animal Welfare Act. Therefore research facility reports do not include these animals. As a result of this situation, a blank report, or one with few animals listed, does not mean that a facility has not performed experiments on non-reportable animals. A blank form does mean that the facility in question has not used covered animals (primates, dogs, cats, rabbits, guinea pigs, hamsters, pigs, sheep, goats, etc.). Rats and mice alone are believed to comprise over 90% of the animals used in experimentation. Therefore the majority of animals used at research facilities are not even counted.

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