458 AM J OPTOM & PHYSIOL OPTICS

Vol. 65, No. 6

FIG. 3. Representative convergence performance

for each session of patient given automated conver-

gence tralning using ADS (top panel) and a matched

control patient exposed to identical target without in-

creasing convergence demand (bottom panel). It is

readily apparent that vergence training increases fu-

slonal ranges for both RDS and vectograms, whereas

control therapy does not result in an increase in fusional

ranges. Vectogram arid RDS performance are pre-

sented In prism diopters. After control therapy the

patient received convergence therapy. (Reprinted from

Am J Optom Physiol Opt 1980;57:21 1.)

found previously in normal patients’ Therefore,

Cooper et al. concluded that the convergence

insufficiency patient must be treated with a

variety of vergence stimuli to obtain transfer.

They also found a decrease in asthenopia on a

scaled questionnaire as well as a flattening of

the patient’s fixation disparity curve after ver-

gence training. During placebo therapy no such

improvement occurred. They concluded that or-

thoptics was effective in remedying convergence

insufficiency with its accompanying symptoms

(Figs. 4 and 5).

Cooper et al.8 have recently used a similar

automated A-B crossover design to determine if

monocular accommodative therapy results in

improved accommodative abilities. Their pa-

tients demonstrated a statistically significant

improvement in accommodative facility, an in-

crease in accommodative amplitude, and a re-

duction in asthenopic symptoms. Within a short

period of time a 55% improvement in amplitude

and a reduction in symptoms occurred. Again,

the experimental design controlled for effects

that were coincidental or due to experimental

bias or placebo (Fig. 6). Improvement in accom-

modative facility is important in the conver-

gence insufficiency population because the ma-

jority of patients with convergence insufficiency

have a secondary accommodative anomaly.7

Kertesz9 showed that automated training with

microprocessor produced anaglyphic, large tar-

get, vergence stimuli that resulted in an im-

provement in vergence ranges and a reduction

in asthenopia in patients who had a convergence

insufficiency. All their convergence patients had

previously failed to benefit from traditional or-

thoptics. Of the 29 convergence insufficiency

patients treated, 23 increased their fusional

ranges with a concurrent alleviation of symp-

toms. Treatment included slowly separating 57

dichoptic targets and RDS which were presented

in both convergent and divergent directions.

Therapy required 5 to 15 sessions. Kertesz and

Kertesz concluded that computer-generated,

large stimuli are more effective in remedying

convergence insufficiency than traditional or-

thoptic techniques. However, Kertesz and Ker-

tesz did not control for stimulus parameters

(large vs. small, stereo vs. flat), motivation, skill

of the therapist, and/or speed of vergence. Thus,

their success may have been due to extraneous

factors. Somers et al.10 used microprocessor-gen-

erated stimuli to treat patients with binocular

anomalies. They reported that patients treated

with computer-produced vergence stimuli

showed more rapid and complete improvement

than traditional techniques. Griffin reported

that microprocessor-produced anaglyphs re-

sulted in an improvement in convergence ranges

similar to traditional methods and a greater

improvement in divergence ranges than tradi-

tional methods.

The above studies have shown the clinical

effectiveness of automated microprocessor-gen-

erated anaglyphs in increasing fusional ranges.

Methods which incorporated operant condition-

ing seemed to be the most effective. However,

many of these research studies utilized sophis-

ticated computer equipment and techniques not

yet available to the clinician. Cooper and

Citron12 demonstrated that a personal computer

(PC) could produce sophisticated anaglyphs,

which could be moved to create a variety of

vergence stimuli.

With the advent of small, powerful PC’s that

can produce sophisticated anaglyphic targets,

commercially available computerized vision