Arthur Jampolsky

Hearing aid employing adjustment of the intensity and the arrival time of sound by electronic or acoustic, passive devices to improve interaural perceptual balance and binaural processing

A hearing aid for a person with asymmetric hearing perception (a weaker ear system and a better ear system) employs conventional frequency-selective amplification (26L) of sound coming to the weaker ears system and frequency selective amplitude adjustment (32) and arrival time adjustment (retardation or relative advancement) (34) of sound coming to the better ears system so that its resultant characteristics match those of the weaker ears system, as aided, or even without aiding the weaker ears system. As a result, sound perceived by both ear systems is matched or balanced, at each frequency, in both arrival time and amplitude. Such interaural balancing effects a great improvement in the binural processing mechanism, which in turn increases speech perception, especially in the presence of general noise or adjacent localized noise sources. The aid may be implemented by a pair of microphones (24L, 24R), one for each ears system. The signal from the microphone to the weaker ears system includes a conventional variable gain amplifier (26L) and a conventional frequency selective filter (13) to provide tailored amplification of the sound to the weaker ears system, insofar as possible. Also the channel to the weaker ears system includes a fixed delay (28) to compensate for a delay in the channel to the better ears system. The signal from the microphone to the better ears system includes a variable gain amplifier (26R) and a set of bandpass filters (30) to cover the audio spectrum in discrete steps. Each filter is connected in series with a selected attenuator (32) and a selected time delay (34) so as to match the perceived arrival time and amplitude level at its band with that of the weaker ears system.

Current Techniques of Adjustable Strabismus Surgery

Adjustable strabismus surgical procedures provide the opportunity to reposition a surgically altered muscle position, which is often necessary for nonaverage cases of strabismus correction. The usual surgical procedure is extended into the postoperative period (same hospitalization) so that the surgeon may satisfactorily monitor the total end result (by cover test and rotations) at the time of adjustment. Adjustable techniques should be considered whenever a desired goal is unlikely to be reached in one surgical session. Recent technical improvements allow satisfactory globe position control during the adjustment stage for ease of recession or resection adjustment. Globe stabilization is attained during surgery and the postoperative adjustment by means of a scleral loop handle, placed near the corneoscleral limbus. Millimeters of adjustment are easily estimated by means of a sliding suture knot technique.

Overcorrecting Minus Lens Therapy for Treatment of Intermittent Exotropia

The purpose of this paper is to determine the value of overcorrecting minus lenses in treating children with intermittent exotropia. The aim with this therapy is to secure an increase in the quality of fusion and to induce a quantitative decrease in the angle of strabismus. Thirty-five children were treated with 2.00 to 4.00 diopters of overcorrecting minus lenses for a median of 18 months duration. Of these, 46% had an improved quality of fusion during therapy; 26% had an improved quality of fusion and also had a quantitative decrease in their angle of deviation; and 28% had an inadequate improvement in their quality of fusion and decrease in the angle of their deviation with this therapy. Two children went from intermittent exotropia to esotropia while wearing their minus lenses--both had high accommodative-convergence/accommodation ratios (11.5 delta/1D and 10.7 delta/1D). Seventy percent of good responders who were followed for at least 1 year after discontinuing the therapy maintained a qualitative or quantitative improvement in their intermittent exotropia.

An Adjustable Transposition Procedure for Abduction Deficiencies

We used an adjustable transposition procedure in two cases of horizontal abduction deficiency (one of lateral rectus palsy and one of Duane syndrome with marked co-contraction). Primary position balanced alignment and maximum balanced rotations were obtained without inducing vertical deviation as the result of the transposition. The vertical force vectors were neutralized by the self-adjusting nature of the vertical rectus union. The procedure allowed for both intraoperative and postoperative adjustment of the result.

Management of Infantile Esotropia

We evaluated the management of infantile esotropia-constant, alternating esotropia before 6 months of age-in 34 children. Planned one-state surgery for satisfactory mechanical alignment was highly predicatable (79 to 84%), and was obtained at any age. Stable bifoveal motor fusion was also obtained but was more frequent with alignment before 2 years of age. The use of postsurgical spectacle orthoptics (minus lenses or prisms, or both) increased the incidence of bifoveal fusion. Surgery alone resulted in bifoveal fusion in 6% of the cases, whereas an overall incidence of 33% bifoveal fusion resulted after the use of postsurgical spectacle orthoptics by some patients. Of those receiving postsurgical spectacle orthoptics, 53% obtained bifoveal fusion. This study demonstrated a correlation between the incidence of secondary A patterns (after surgery for V esotropia) and the amount of horizontal muscle surgery done in combination with bilateral inferior oblique muscle myectomies.

Alcohol and marijuana effects on static visual acuity.

&NA; Static visual acuity was measured at two contrast levels (12 and 49%) in ten subjects in a double blind experiment involving five drug conditions of alcohol and marijuana (0.5 ml and 1.0 ml/kg body weight of 95% ethanol, 8 and 15 mg &Dgr;‐9‐tetrahydrocannabinol (THC), and a placebo). We found no statistically significant change in static visual acuity for any of the dose levels at any of the measurement times up to six hours following drug ingestion; this is sharply contrasted with the marked decrements in acuity which were found in the same subjects under the same drug conditions when the targets were in motion and required coordinated eye movements for their resolution.

Plasticity of human motion processing mechanisms following surgery for infantile esotropia

Monocular oscillatory-motion visual evoked potentials (VEPs) were measured in prospective and retrospective groups of infantile esotropia patients who had been aligned surgically at different ages. A nasalward-temporal response bias that is present prior to surgery was reduced below pre-surgery levels in the prospective group. Patients in the retrospective group who had been aligned before 2 yr of age showed lower levels of response asymmetry than those who were aligned after age 2. The data imply that binocular motion processing mechanisms in infantile esotropia patients are capable of some degree of recovery, and that this plasticity is restricted to a critical period of visual development.

Dissociated Vertical Deviation: An Asymmetric Condition Treated with Large Bilateral Superior Rectus Recession

Bilateral superior rectus recessions were performed on 25 patients for dissociated vertical deviation (DVD). Large recessions (at least 10 mm from the original insertion) have proved effective and safe, although all patients were slightly undercorrected. There were no complications of ptosis, upper lid retraction, alterations of palpebral fissure width, failure of upgaze, oblique dysfunction or overcorrection. The DVD was always asymmetric, with the greater deviation in the non-dominant eye. Forty percent of the patients had a decompensated asymmetry manifested by unilateral hypertropia of at least 10 prism diopters in addition to the DVD. These patients require an asymmetrical amount of surgery. Two such patients required reoperation, not because of residual DVD, but because of failure to correct this hypertropia. Currently we do bilateral superior rectus recessions of greater than 10 mm OU for DVD, reserving unilateral surgery for the patient with such deep amblyopia that he will never fix with the operated eye. An eye with manifest hypertropia in addition to DVD requires at least five more millimeters (greater than 15 mm) than the fixating eye. Maximum amounts of recession have not yet been determined.

Preoperative Alternate Occlusion Decreases Motion Processing Abnormalities in Infantile Esotropia

We have examined the effects of preoperative, full-time alternate occlusion on the development of visual motion processing mechanisms. Motion visual evoked potentials (MVEPs) were recorded longitudinally in 14 infantile esotropia patients during the course of standard preoperative occlusion therapy. The MVEP in these patients was initially asymmetric in a fashion consistent with a nasalward/temporalward response bias, with a motion asymmetry significantly higher than that of age-matched normals. The magnitude of the developmental motion asymmetry declined significantly after an average of 24 weeks of alternate occlusion. This result implies that the binocular motion-sensitive cells underlying the MVEP retain some degree of plasticity up to at least 1 year of age. Our data suggest further that the persistence of motion asymmetries in untreated infantile esotropia patients is maintained by an active process that can be disrupted by alternate occlusion. Alternate occlusion apparently eliminates a form of abnormal binocular interaction that supports the persistence of the motion asymmetry. We propose that one of the necessary pre-conditions for symmetricization of motion processing in infantile esotropia is the absence of abnormal competitive binocular interactions.

Diagnostic injection of Xylocaine into extraocular muscles.

In situations where it is unclear which extraocular muscle is causing anomalous eye movement or to what extent one of two muscles is responsible, temporary paralysis of the muscle with Xylocaine may provide the answer. The procedure is to inject 0.2 to 0.5 cc 2% Xylocaine directly into the muscle using electromyography (EMG) for precise localization, a technique similar to that of therapeutic injections of botulinum toxin (Oculinum). The procedure is especially useful for Duanes syndrome, superior oblique palsy, and other situations where abnormal muscle insertions or innervations make diagnosis of the muscle responsible for an eye movement anomaly difficult and surgery unpredictable.