field of view in which the enlargement and spatial shift of the visual field exactly match the angular measurement of the deviation (See Figure 6, above). Thus, they experimentally proved Cass (27) and Costenbader’s (12) observations of panoramic viewing.

One can easily demonstrate panoramic viewing in X(T). First, measure and plot a binocular confrontation field with eyes aligned. Then repeat the procedure with an eye exodeviated. The binocular field will most likely be larger by the amount of the deviation.

Costenbader (12) has stated that X(T) has NRC with or without suppression. He reported that visual confusion was present in 61% of DEX(T) which he felt supported his contention concerning NRC. Bair (31) noted visual confusion present in 316 out of 528 DEX(T)s. Neither author defined how they measured visual confusion.

Most authorities disagree with Costenbader and Bair, who reported that patients with DEX(T) generally do not report diplopia or confusion (1,9,11,12).

The major proponents of suppression theories are Jampolsky (23,93) and Knapp (94) who maintain that X(T)s have binocular, hemiretinal, temporal suppression

which occurs only during exodeviation Jampolsky (84) used a Risley prism and a red lens to measure suppression in X(T)s. He reported that suppression extends from the fovea of the deviating eye into the temporal retina to the diplopia point (the point where the object of regard falls on the deviating eye). Jampolsky also reported that the nature of the stimuli influenced suppression patterns.

Similar findings were initially reported by Travers (95) who found two suppression zones, one at the fovea of the deviating eye and another at the diplopia point.

Pratt-Johnson & Wee (96) used red-green anaglyphs with a Lee Screen and polaroid lenses to measure suppression areas. Using polaroid lenses to dissociate the eyes, they found that X(T)s had a strong suppression zone extending from the deviating fovea to the diplopia point (See Figure 7, below). Contrary to Jampolsky (93), they found harmonious ARC (HARC) without evidence of suppression with red-green targets peripheral to the fovea of the deviating eye. They also reported, like Travers (95) two suppression areas, one at the fovea of the deviating eye and the other at the diplopia point. Like Jampolsky, they reported that

Figure 7 (cooper & Medow): Various reported suppression patterns for X(T). OD is fixating; OS deviating. (All suppression patterns described are with the OS deviating.)

Pattern 1: Iwo suppression areas corresponding to the fovea and point zero (diplopia

point) of the left eye. Pattern 2: dwnb bell shaped suppression zone extending from diplopia point to deviating fovea. Pattern 3: “D” shaped suppression zone including deviating fovea and diplopia point. Pattern 4: temporal hemiiretinal suppression. Note targets on the left side (animals) are seen by the left eye and seen where they are in real space demonstrating

HARC.

Figure 6 (Cooper & Medow): Experimental design in Cooper J, Feldman J: Panoramic viewing visual acuity of the deviating eye, and anomalous retinal correspondence in intermittent exorropia of the divergence excess type. (Am J Optomn Phys opt 1979,~ 56:422- 429). OD is fixating a light source behind a translucent screen ( ). Wizen the left eye is deviated (--) both visual acuity at the objective angle and binocular field of view are measured. The measurements were repeated with the left eye aligned (...). Eye movements were monitored. Results show during deviation simultaneous perception of fixation target ( ), 20/20 visual acuity in the deviating eye, wit/i accurate spatial projection of the peripheral target. The HARC (harmnonious anomnalous retinal correspondence) was associated with the increase in the field of view while deviating i.e., panoramic viewing.

196