Comparison of suppression, stereoacuity, and interocular differences in visual acuity in monovision and acuvue bifocal contact lenses.

PURPOSE: The relationship between visual acuity and stereoacuity has been well documented: as binocular visual acuity increases, stereoacuity improves. We compared interocular differences in visual acuity and stereoacuity in two presbyopic soft contact lens modalities, monovision and a new soft bifocal contact lens, the Acuvue Bifocal. The Acuvue Bifocal is hypothesized to show a smaller interocular acuity difference, increased stereoacuity, and decreased suppression over monovision at distance and near. METHODS: Monovision patients wearing Acuvue or Surevue soft contact lenses were tested for visual acuity, stereoacuity, and suppression at distance and near. Stereoacuity was tested with the Randot Stereotest (near) and the BVAT (distance). Suppression was evaluated with the Acuity Suppression Vectogram (near) and the BVAT (distance). Patients were then fit with the Acuvue Bifocal in each eye. After wearing the lenses for 1 week, the same tests of visual acuity, stereoacuity, and suppression were performed. RESULTS: The mean interocular acuity difference (IAD) at distance with monovision was 0.712 logarithm of the minimum angle of resolution (logMAR) (SD = 0.275) and 0.188 logMAR (SD = 0.252) (p < 0.001) with the Acuvue Bifocal. At near, the mean IAD with monovision was 0.420 logMAR (SD = 0.183) and 0.137 logMAR (SD = 0.147) (p < 0.001) with the Acuvue Bifocal. Of the monovision subjects, 89% (17 of 19) demonstrated suppression at near while only 26% (5 of 19) did with the bifocal lenses (statistically significant at p < 0.001). Stereoacuity at near improved from a median of 200 sec arc with monovision to 50 sec arc with the bifocal lenses. CONCLUSIONS: In this study, correcting presbyopia with the Acuvue Bifocal versus monovision resulted in a statistically significant decrease in the interocular difference in visual acuity at distance and near. The decreased interocular difference in visual acuity improved certain aspects of binocularity as demonstrated by a decrease in suppression and an increase in stereoacuity.

The effect of ocular dominance on the performance of professional baseball players.

OBJECTIVE: The purpose of the study was to determine whether a performance difference exists between baseball players with "same" (right-right) and "crossed" (right-left) hand-ocular dominance. DESIGN: A cohort study design was used. PARTICIPANTS: Four hundred and ten major and minor league members of the Los Angeles Dodgers professional baseball team. INTERVENTION: Measurement of ocular dominance. MAIN OUTCOME MEASURES: Batting average and earned run average (ERA). RESULTS: Same/crossed dominance (with P values in parentheses) are as follows: Batting averages: major league-0.271/0.251 (0.20); minor league-0.274/0.270 (0.57); ERA: major league-3.34/3.56 (0.66); minor league-4.00/4.20 (0.54). CONCLUSIONS: Hand-ocular dominance patterns do not have an effect on batting average or ERA.

The visual function of professional baseball players.

PURPOSE: To measure the visual acuity, stereoacuity, and contrast sensitivity of professional baseball players. METHODS: Three hundred eighty-seven professional baseball players underwent several tests of visual function including distance visual acuity. Stereoacuity was evaluated at near by the Randot test and at distance by both contour and random dot targets. Distance stereoacuity was also tested under timed and untimed conditions. Contrast sensitivity was evaluated by the Vision Contrast Test System, Contrast Sensitivity Viewer, and Binocular Visual Acuity Tester. RESULTS: Visual acuity (measured with players' regular distance correction) in 774 eyes ranged from 20/8.89 to 20/100. Near stereoacuity ranged from 23 to 37 seconds of arc, mean untimed distance contour stereoacuity from 55 to 35 seconds of arc, and mean untimed distance random dot stereoacuity from 98 to 76 seconds of arc. The results under timed conditions were 86 to 65 seconds of arc (timed distance contour stereoacuity) and 104 to 83 seconds of arc (timed distance random dot stereoacuity). Statistically significant differences were found between major and minor league players on tests of untimed distance contour and random dot stereopsis, and on contrast sensitivity testing with the 3.0- and 6.0-cpd gratings using the Contrast Sensitivity Viewer. CONCLUSIONS: Professional baseball players have excellent visual skills. Mean visual acuity, distance stereoacuity, and contrast sensitivity are significantly better than those of the general population.

Comparison of fixation disparity measurements obtained with the Wesson Fixation Disparity Card and the Sheedy Disparometer.

We compared the fixation disparity measurements obtained with the Disparometer to those of the Wesson Card. Previous studies suggest that the measurements obtained by these two instruments gave different results. The results of previous studies were based on the analysis of pooled data, which may have led to spurious results. Analysis of our data done in this manner (pooled data) revealed the same findings. However, after analysis of the data based on the separation of subjects according to phoria (exophoria/esophoria), no statistically significant difference was found between the measurements obtained with the Wesson Card and those with the Disparometer.

Electronic submission of abstracts for the annual meeting of the American Academy of Optometry.

Recently the American Academy of Optometry conducted a 2-year trial in which abstracts submitted for presentation at the Annual Meeting could be transmitted to the Academy in electronic form. Electronic submission has many advantages for the author as well as for the Academy and therefore has now been endorsed as the preferred method of submission for future meetings. Step-by-step procedures for electronic submission are described.

Vertical rectus muscle transposition and botulinum toxin (Oculinum) to medial rectus for abducens palsy.

Ten adult patients developed sixth-nerve palsy after trauma or a cerebral tumor. No clinical evidence of recovery of function was noted by at least 8 months after onset. All patients underwent total transposition of the superior and inferior rectus muscle insertions to the area of the lateral rectus insertion, accompanied by botulinum toxin (Oculinum) injection of the ipsilateral medial rectus. These patients developed a mean diplopia-free field of 51 degrees, with a diplopia-free field in the abducted field of 20 degrees. This procedure involved surgery on only two rectus muscles, but the results compared favorably with surgical strategies involving three rectus muscles. Thus, the risk of developing anterior segment ischemia was greatly reduced.

Fresnel vs. conventional prisms: their effects on the apparent fronto-parallel plane horopter.

Among the inherent optical aberrations found in conventional crown glass or resin prisms is the property known as nonuniform relative magnification. Prisms, by definition, displace an image by a given amount. However, the final size of the image is nonuniform, being relatively larger toward the apex than toward the base of the prism. At present, reduction of the amount of nonuniform magnification is achieved by fabricating the prismatic correction on relatively steeper base curves (i.e., +9.00 D). This research deals with an attempt to reduce nonuniform magnification using Fresnel prisms. In this way, image displacement is created only by small prism apices, each of equal power and each producing identical image displacement resulting in a smaller degree of nonuniformity of image size. In this experiment, equal amounts of prism were fabricated on flat and steep base curves, using either conventional or Fresnel prism. The precise magnitude of the nonuniform relative magnification for each set of lenses was measured by a number of observers using the Apparent Fronto-Parallel Plane (AFPP) horopter apparatus. After statistical analysis using both an analysis of variance (ANOVA) and a matched pair t-test, there proved to be no significant reduction in the amount of nonuniform relative magnification when Fresnel prisms were used in place of conventional ground prisms. Furthermore, maximal reduction of this aberration appears to be effected only by fabricating such corrections on steep base curves. Relative magnification is more a function of the orientation of the base-apex meridian and the angle of incident light from an extended object than of effects of prism type or thickness.

Performance of the dot visual acuity test with uncorrected ametropia resulting in target blur.

The dot visual acuity test is used to test the acuity of children between the ages of 2 and 4 years who do not respond to the tumbling E test. Because the test involves the detection of a black dot on a white background it is appropriate to ask if the detection threshold is lowered artificially in the presence of target blur. Twenty-one children (42 eyes) were used in the study. Refractive errors were fully corrected and each subject's lag of accommodation was measured. A monotonic decrease in acuity was found with increasing amounts of optical blur. The explanation for the decreased acuity is found in the reduced retinal image contrast of the blurred target.

The use of botulinum toxin in the medical management of benign essential blepharospasm.

Twenty-eight patients with mild or moderate cases of benign essential blepharospasm were treated with botulinum toxin Type A. Average follow-up was six months. The injection technique used on these patients is illustrated. The treatment was effective in virtually all patients treated, although transient; the mean interval of relief of spasm was approximately two and one-half months. Potential side effects include ptosis and epiphora. Botulinum toxin as an initial treatment or as an adjunct in postsurgical residual blepharospasm shows promise in this preliminary study.

The dot visual acuity test--a new acuity test for children.

A new visual acuity test is described for children between the ages of 2 and 4 years who are unable to respond to the tumble E games. For children old enough to respond to both tests, the visual threshold are the same. Fifty percent of the children who could not respond to the tumble E game will be able to be tested with this new method. The new is rapid, inexpensive, and cannot be memorized, thereby allowing the test to be given at frequent intervals.

Auditory feedback in the control of congenital nystagmus.

The control of oscillatory eye movements in congenital nystagmus was studied in five human subjects. Auditory feedback of eye position and eye motion was given to each subject to aid in controlling the abnormal eye movement. Less than one hour was needed for all the subjects to learn to use the auditory information. Reductions in eye movement amplitude ranged from 41 to 73%. Sensory functions like visual acuity and contrast sensitivity also improved under the auditory feedback condition. Auditory feedback of eye position is thought to have potential usefulness in the treatment of congenital nystagmus.

How to write an abstract of a paper or a report to be presented at the annual meeting of the American Academy of Optometry.

Although the General Papers Program (held on Saturday, Monday and Tuesday afternoons at the Annual Meeting of the Academy) has expanded to a format in which 20-minute papers and 10-minute reports are presented simultaneously in 4 or 5 rooms the committee continues to receive abstracts for approximately 25 percent more papers and reports than the program can accommodate. The committee's task of selecting papers and reports is complicated by the failure of many writers of abstracts to include sufficient and pertinent information in their abstracts. This presentation lists the essential elements of an acceptable abstract, and tabulates the reasons for non-acceptance of abstracts.

An evaluation of accommodation response in amblyopic eyes.

A laser optometer and an auditory feedback system were used to assess the accommodative response in normal eyes, and in the dominant and amblyopic eyes of amblyopes. Although the accommodative response improved in amblyopic eyes when these eyes achieved steady foveal fixation it is not clear how much of the subnormal acuity in amblyopic eyes is due to eccentric fixation, unsteady fixation, inappropriate accommodation, refractive error or some combination of these factors.

Control of unsteady, eccentric fixation in amblyopic eyes by auditory feedback of eye position.

A technique for providing amblyopes with auditory feedback signals of eye position errors is described. With auditory cues, 12 adult eccentrically fixing amblyopes with strabismus and/or anisometropia have been able to maintain steady and foveal fixation with the amblyopic eye. The changes observed in fixation patterns with auditory feedback were both quantitative and qualitative; with such feedback, amblyopes often exhibited sequences of normal-appearing fixation. Some of our subjects have been successful in maintaining steady foveal fixation for short periods of time after feedback is turned off, apparently using visual error signals. For two subjects, feedback also promoted major improvements in smooth tracking performance. We conclude that the use of auditory feedback of eye position has significant value for basic studies of the mechanisms underlying amblyopia and potentially for the clinical treatment of this condition.

Changes in retinal correspondence following surgery for intermittent exotropia.

An intermittent exotrope of 54delta had harmonious anomalous correspondence when squinting and normal correspondence when bifoveally fixating. Measures of the angle of deviation (H) and angle of anomaly (A) were made at the first postoperative dressing 6 hr after surgery (H = 8--14delta esotropia, A = 0--54delta exo) and at several times over a 2.5-mo period during which a second operation was performed. The final result was 3delta of exophoria with normal correspondence when fusing and harmonious anomalous correspondence (A = 3delta exo) when fusion was disrupted. The change in angle of anomaly created by the surgery cannot be explained by changes in fusional vergence. Halldén's "sensory-fusion" mechanism, which is based on diplopia resulting from stimulation of disparate retinal points, is more useful in explaining the obtained results.

Visual acuity at different retinal loci of eccentrically fixating functional amblyopes.

Visual acuity was measured in eccentrically fixating amblyopic subjects to determine the contribution of sensory (inhibitory) and motor (retinal-locus) components of the acuity loss. A unique aspect of this research involved the subjects' use of auditory feedback to control their unsteady and eccentric fixation while responding to flashed (800 msec) or continuously presented targets at various eccentricities in the visual field. All 4 amblyopic eyes had maximum visual acuity at the fovea; from there, the acuity declined approximately symmetrically into the nasal and temporal periphery. Foveal acuity for these amblyopic eyes was depressed from the acuity at the fovea of the normal eye. We conclude that Worth's explanation of eccentric fixation (eccentric fixation develops in an attempt by the amblyopic eye to fixate with a peripheral retinal locus having higher acuity than the fovea) cannot apply to our amblyopes. The acuity losses exhibited by the amblyopic eyes studied have a sensory (inhibition) component and a motor (retinal-locus) component, the sensory component being greater for small degrees of eccentric fixation and the motor component being greater for large amounts of eccentric fixation.