Biomedical subjects
Publications and source records attributed to R P Rutstein.
This paper discusses the use of vertical fixation disparity (VFD) measurements to determine a patient's ability to adapt to vertical prism. Vertical vergence adaptation for orthophoric patients, hyperphoric patients, and patients with vertical deviations associated with superior oblique paresis is reported. The effect of orthoptic training on the ability to adapt to vertical prism is also reported.
To determine the efficacy and stability of therapy, we reviewed the charts of 64 amblyopes with strabismus and/or anisometropia who had been treated by direct occlusion. For patients aged 7 years or less (N = 39), 90% (35/39) showed some acuity gain, with 69% (27/39) achieving at least a doubling of acuity (0.3 log units). Fifty-four percent obtained 20/40 (6/12) or better after an average treatment period of 3.8 months. Some reduction in visual acuity (VA) subsequently occurred for 75% (24/32) of those patients followed. For patients aged 8 years or more (N = 26), 77% (20/26) showed some acuity gain with 31% (8/26) improving at least 0.3 log units. Twenty-seven percent (7/26) obtained 20/40 (6/12) or better after an average treatment period of 4.2 months, although no patients older than 10 years (N = 13) achieved 20/40 (6/12). Loss of some of the acuity gain subsequently occurred for 67% (12/18) of those followed. These findings indicate that VA can be improved by patching therapy in most patients older than 7 years, but the acuity improvement is somewhat less than in younger patients. At least 67% of all amblyopes followed for 1 year lost some of the acuity gain after cessation of therapy, regardless of the age when treated. As a reduction of the acuity gain is likely to occur within the first year after cessation of therapy, it is recommended that amblyopic patients of all ages be followed at regular intervals.
The clinical findings for 29 patients with Duane's retraction syndrome (DRS) are reported. Similar to other studies, a preponderance of females, left eye involvement, and type I DRS occurred. The incidence of both anisometropia and amblyopia was somewhat higher than for the normal population. Unexpectedly, complaints of diplopia existed for seven patients.
We studied the changes in retinal correspondence for 32 constant strabismic patients whose ocular alignment was altered either surgically or spontaneously over a period of time. Patients having normal retinal correspondence (N = 10) generally maintained normal correspondence after the change in ocular alignment. Patients with anomalous retinal correspondence (N = 20) behaved differently. Thirteen of these patients maintained anomalous correspondence and seven patients developed normal correspondence after the change in ocular alignment. For the patients who developed normal correspondence, the direction of the strabismus also changed. We conclude that normalization of retinal correspondence is more likely to occur in strabismic deviations that are overcorrected.
Cyclodeviations may interfere with fusional ability and may also affect the refractive status. If a cyclodeviation is present, the axis of astigmatism determined under monocular viewing conditions will be different from that determined under binocular viewing conditions. The change in the axis should correlate with the amount and direction of the cyclodeviation. We measured the refractive status under monocular and binocular viewing conditions of patients with cyclodeviation of 3 degrees or more and astigmatism of 1.00 D or more. All patients had superior oblique paresis. We then compared the change in the axis of astigmatism to the cyclodeviation measured with the double Maddox rod test. The average change in the axis of astigmatism was 5.0 degrees and the average cyclodeviation was 5.2 degrees. We recommend that all patients with 3 degrees or more of cyclodeviation, 1.00 D or more of astigmatism, and capable of fusion should have their refractive status determined under binocular viewing conditions.
Preferential looking using square waves is commonly used to measure visual acuity of infants. Since sine-wave gratings have the advantage of presenting only a single spatial frequency, we completed a study to develop and validate a set of acuity cards using sine waves. The subjects were 83 children (mean age = 41.5 months, range = 3 to 69 months). The sine-wave cards were compared with Teller cards. Identical visual acuity was determined in 83% of the cases. Wilcoxon non-parametric analysis provided no evidence to reject the null hypothesis of equal visual acuities between the two methods. We conclude that sine-wave cards may be used to measure the preferential looking acuity of children.
The purpose of this study was to assess a new criterion for binocular comfort analogous to the classical Sheard's criterion. Instead of equating the fusional demand with the monocular phoria as is done when Sheard's criterion is applied, the new criterion uses a calculated binocular fusional demand. The binocular demand was derived using a clinical measurement of the convergence accommodation per convergence (CA/C) ratio. Sheard's criterion was also evaluated. Other commonly used indicators of binocularity (heterophoria, vergences, accommodative amplitude, facility and response, fixation disparity, and the associated phoria) were measured. One hundred subjects (52 males, 48 females; mean age 26 years) were classified as either symptomatic or asymptomatic by an interviewing clinician. The examining clinician was intentionally masked as to the classification of the subjects. We hypothesized that the new criterion would best discriminate between the two groups of patients inasmuch as it is based on currently accepted dual-interaction models of accommodation and vergence. Our analysis confirmed that the CA/C ratio corresponded closely to those published previously (mean = 0.06 D/delta). Significant differences (p less than 0.05) were determined between the symptomatic and asymptomatic groups for gender, near phoria through a +2.00 D add, accommodative amplitude, positive vergences at near, and both the classical Sheard's and the new criterion. The new criterion was the best discriminator between the groups, identifying 72% correctly, an improvement of 6% over the classical Sheard's. However, various stepwise discriminant analysis procedures consistently failed to demonstrate that the calculated binocular fusional demand or the new criterion was superior to the near phoria or the classical Sheard's value. These results suggest potential clinical utility for new procedures based on recently described models of accommodation and vergence, but further development appears necessary.
The correspondence status of 68 constant, early-age onset strabismics was evaluated with three common clinical tests to determine the prevalence of anomalous retinal correspondence (ARC) and which clinical features of the strabismus were most highly associated with the ARC. Ninety-six per cent, 71%, and 51% of the patients manifested ARC with the striated lens test, the synoptophore, and the afterimage test, respectively. The clinical features of the strabismus that were correlated, although weakly, with the diagnosis of ARC were: (1) the magnitude of the deviation at near for the striated lens test; (2) the age of the patient at the time of testing and the laterality of the deviation on the synoptophore; and (3) the age of the patient at the time of testing, the change in the deviation from distance to near, and the spherical equivalent refractive error for the afterimage test. A low correlation also existed between the age of the patient and the depth of ARC (superficial or deep-rooted). We conclude that the clinical features of strabismus cannot be utilized effectively to predict the status of retinal correspondence.
The refractive changes of pediatric patients who were prescribed overminus lenses for exotropia were evaluated. Overminus lenses means additional minus power over the lenses required to correct the refractive error at distance. Forty exotropic patients, ages 1 to 15 years, were prescribed overminus lenses (-0.50 D to -3.75 D) for a period of 9 to 86 months. A small but significant correlation was found between the initial refractive error and the mean annual change toward myopia. Other factors such as age when treatment was given, duration of therapy, amount of overminus, and the amount of the exodeviation had little effect on the rate of myopic change. The mean annual changes in refractive error for hyperopes (-0.13 +/- 0.44 D, N = 15), emmetropes (-0.26 +/- 0.37 D, N = 17), and myopes (-0.75 +/- 0.77 D, N = 18) were similar to values reported in the literature for nonexotropic children.
Explore the source record for details and available documents.
The purpose of this study was to assess the effects of horizontal and vertical vergence training on fusional vergences and the fixation disparity (FD) curve. Thirty-four subjects were divided into three groups. One-third served as controls and the other two-thirds underwent 5 h of supervised horizontal and vertical vergence training, respectively. Before and after the 4 week training period, vergences and FD curves were measured by a single individual who was intentionally uninformed of each subject's group. We hypothesized that the subjects in the horizontal training group would have increased vergence amplitudes and flatter FD slopes. Our analysis revealed that the positive vergences increased significantly for those in the horizontal group. No evidence was found to suggest changes in any variables related to the FD curve. Because type II errors were likely to be unacceptably large, further work is necessary to determine the relation between fusional vergence training and variables derived from the FD curve.
The purpose of this study was to assess the effects of horizontal and vertical vergence training on vertical fusional amplitudes, the vertical fixation disparity (VFD) curve, and prism adaptation. Thirty-four subjects were divided into three groups. One-third served as controls and the other two-thirds underwent 5 h of supervised horizontal and vertical vergence training, respectively. We hypothesized that subjects in the vertical group would manifest increased vertical vergence amplitude and coefficients of adaptation in concert with flatter VFD slopes. Before and after the 4-week training period, vertical vergences, fixation disparity (FD) curves, and coefficients of vertical prism adaptation were measured by a single individual who was intentionally uninformed of each subject's group. Analysis of the data suggests that changes in the vertical fusional amplitudes increased slightly. Although changes in the VFD slope and coefficient of prism adaptation were not statistically significant, the changes were much greater in the vertical group and in the hypothesized direction. We suggest that the results offer preliminary support for our hypothesis.
Acute acquired comitant esotropia in the older child, adolescent, and young adult may represent uncorrected accommodative esotropia. Three young patients developed spontaneous diplopia associated with acute comitant esotropia. In all cases, cycloplegic refraction revealed high uncorrected hyperopia suggesting late onset accommodative esotropia. However, for one patient an intracranial neoplasm precipitated the strabismus and for the other patients the hyperopic correction did not alter the deviation. Clinicians confronted with older children or adolescent patients with acute comitant esotropia associated with large uncorrected hyperopia should not hastily classify the deviation as being accommodative in etiology. Although the latter is possible, the hyperopia may be coincidental and masking an underlying mechanism.
Accommodative spasm (AS) is rarely reported in the literature. We studied 17 patients with accommodative spasm. Most patients were clinically emmetropic. Ten patients also manifested a spasm of the near reflex (SNR). The probable etiology of the accommodative disorder for most patients was psychogenic as revealed by case histories and visual field analysis. Treatment consisted primarily of plus reading lenses and, in some instances, orthoptic training. Some patients also underwent psychological counseling. Follow-up ranged from 2 months to 30 months. Although visual symptoms improved for most patients, only four patients had complete resolution of the spasm.
The purpose of this study was to determine the efficacy of computerized fusional vergence therapy and the effect of two different vergence training velocities. Six subjects received positive vergence training using a slow vergence training rate (0.75 delta/s) and six subjects received positive vergence training using a fast vergence training rate (5.00 delta/s). Six subjects served as controls and did not receive therapy. The duration of therapy was 80 min over a period of 4 weeks. All training activities were monitored. All vergence evaluations were double masked. Subjects using a slow training rate showed significant increases in positive vergence ranges as measured with the major amblyoscope, whereas subjects training with fast rates did not. We conclude that vergence therapy using a computerized video display is an effective technique for increasing the amplitudes of positive fusional vergence and that slower rates are more productive than faster rates.
Despite the close association of convergence and accommodation, accommodative dysfunction is not often associated etiologically with exotropia. We studied 13 adolescent and young adults having intermittent exotropia and severely reduced accommodative function. Most patients had a prolonged history of visual symptoms that had not responded to therapy in the past. Clinical testing indicated that the patients had severely reduced amplitudes of accommodation and difficulty sustaining accommodation. Exotropia was manifest when the accommodative response was inadequate; relative orthophoria existed when the accommodative response was adequate. Treatment of the accommodative defect as well as the strabismus was successful for some patients. We recommend careful evaluation of accommodation for adolescent and young adults with exotropia to rule out an accommodative defect as a contributing cause.
We studied vertical fixation disparity (VFD) with the purpose of assisting the clinician in the evaluation of patients having vertical heterophoria and/or vertical anisometropia and in the prescription of an appropriate vertical prismatic correction. Our research shows that VFD represents a relatively stable and reliable measurement of the vertical deviation; provides the clinician with a mechanism to study a patient's ability to adapt to an induced vertical fusional demand; and provides a process to determine the amount of the vertical prismatic correction.
The purpose of this study was to determine the characteristics of the clinically measured vertical fixation disparity (VFD) curve and the ability to adapt to vertical prism for patients who have a vertical heterophoria and are comfortably wearing vertical prism, and to relate these data to similar findings for nonvertical heterophoria patients. The correlation between the amount of vertical prism that was being worn comfortably and the amount of vertical prism that reduced the VFD to zero was also evaluated. The results indicate that patients with vertical heterophoria who are wearing vertical prismatic corrections comfortably have VFD curves with shapes and slopes similar to nonvertical heterophoria patients; have lower coefficients of adaptability to vertical prism than nonvertical heterophoria patients; and the amount of the vertical prismatic correction to produce visual comfort can be determined by the vertical prism that reduces the VFD to zero.