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At least 1,135 records · Page 63Linked to original sources
PubMed1983

Use of various measures of visual acuity and contrast sensitivity in the evaluation of monocular occlusion and active vision training of three adult amblyopes.

Three adult amblyopic patients who underwent vision training involving monocular occlusion of the nonamblyopic eye and stimulation of the amblyopic eye using simple fixation exercises and a spinning grating procedure were evaluated using five different types of acuity testing and two methods of contrast sensitivity. It was found that contrast sensitivity and isolated Landolt C acuity improved sooner and to a greater extent than the more complex visual acuity tasks. One patient who improved only on the simpler tasks complained that the enhanced contrast due to training made vision in that eye less acceptable because it was more confusing. The results show that multiple measures of visual acuity and contrast sensitivity are necessary to adequately monitor the effects of occlusion therapy.

Adult↗
PubMed1983

A comparison of the results of tonic and phasic vergence training.

Thirty-four healthy asymptomatic young adults were randomly divided into two groups. All subjects underwent training aimed at expanding the vergence ranges. The training in one group consisted of tasks emphasizing smooth, slow activities. The other group trained using quicker, stepwise, more phasic tasks. The vergence ranges were subjectively measured using a small (1.72 degree diameter) target in a major amblyoscope. The study lasted 6 weeks. The first 3 weeks served as a control period over which time the vergences proved to be stable. The training was done for 10 min on the weekdays of the last 3 weeks of the study. Analysis of the data indicates that the group training via the stepwise or phasic paradigm showed greater increases in both the positive and negative vergences. Both groups achieved substantial increases in both the negative and positive vergences. The significance of these results is discussed.

Adult↗
PubMed1984

Effect of monocular occlusion on lateral phoria.

Several experiments have shown that monocular occlusion (MO) leads to a variety of changes in the visual functioning of the non-occluded eye. An experiment was conducted to assess the effect of 24 hr of MO on the lateral phoria, a binocular phenomenon. The results demonstrated marked tendencies for increased esophoria after MO, especially for near vision. Follow-up tests revealed that normal phoria was re-established 24 hr after the termination of MO. The results are discussed in the context of the use of MO in treatment procedures for visual dysfunctions and their implication for future investigations.

Accommodation, Ocular↗
PubMed1985

Clinical management of nearpoint stress-induced vision problems.

Functional vision problems caused by or associated with nearpoint vision stress include: accommodative disorders (insufficiency, ill-sustained, infacility); abnormal heterophorias (esophoria, high exophoria); and vergence disorders. These vision disorders cause problems with acuity, comfort, and performance (efficiency). A combination of lens prescribing, vision therapy, and work/study visual hygiene recommendations can eliminate or greatly reduce nearpoint stress-induced vision problems.

Eyeglasses↗
PubMed1985

Effect of visual training on the vertical vergence amplitude.

Visual training has an effect on the vertical vergence amplitudes. Three mature symptomatic patients exhibited a significant increase in the vertical vergence which compensates for the vertical heterophoria. Subjects with normal binocularity and hence no vertical heterophoria did not exhibit increased vertical vergence amplitudes after training.

Adult↗
PubMed1987

Efficacy of computerized vergence therapy.

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.

Adult↗
PubMed1988

Horizontal and vertical vergence training and its effect on vergences and fixation disparity curves: I. Horizontal data.

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.

Adult↗
PubMed1988

Horizontal and vertical vergence training and its effect on vergences, fixation disparity curves, and prism adaptation: II. Vertical data.

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.

Adaptation, Ocular↗
PubMed1988

A model of spatial localization and its application to strabismus.

Visually guided, spatially oriented behavior involves an ongoing integration of signals regarding the loci of the retinal images and the position and orientation of the eye. In the strabismic this requires an altered spatial metric resulting from a functional readaptation to avoid confusion and diplopia. A comparator mechanism for evaluating these two signals is presented. A case report using "disruptive" therapeutic procedures that deliberately alter the strabismic's visual-postural control system is presented. A treatment plan for altering the anomalous binocular link, a characteristic of the well adapted strabismic, is described and related to the comparator mechanism.

Adaptation, Physiological↗
PubMed1988

Visual therapy results for convergence insufficiency: a literature review.

This paper is a review of the literature relative to treatment results for convergence insufficiency utilizing vision therapy training procedures. Vision therapy is shown to improve the nearpoint of convergence and fusional convergence and to ameliorate associated symptoms. The overall cure rate is 72%. Furthermore, the training results appear to persist for at least 2 years if the patients are initially cured and are independent of age until the late presbyopic years. Also, recent studies indicate the type of training procedures which yield the most effective training results.

Adolescent↗
PubMed1992

Hypotony and corneal edema secondary to patching in normal eyes.

Over the past decade investigators have used patching when studying corneal response to eye lid closure. In these studies, corneal edema was thought to be secondary to hypoxia, and the results were used to predict corneal response to contact lens wear. None of these studies have measured or controlled the intraocular pressure (IOP) during eye patching. Reports in the literature indicate that hypotonous and hypertensive events may induce corneal edema. In order to evaluate the IOP and corresponding corneal changes, measurements were made on subjects with patched eyes. Thirty subjects were unilaterally patched and randomized into tight and light patch groups to maintain complete lid closure for 4 h. Measurements of IOP and corneal thickness (CT) were made at baseline and at hourly intervals. The contralateral eye served as the control for each subject. Our results indicate a significant decrease in IOP and a corresponding increase in CT in the tight patched group as compared to the light patch group, and baseline controls. These results suggest that the corneal edema which results from patching of the eye may be due to hypotony, or a combination of factors affecting corneal function, rather than hypoxia.

Bandages↗
PubMed1992

Glenn A. Fry Award Lecture 1991: perceptual manifestations of imperfect optics in the human eye: attempts to correct for ocular chromatic aberration.

The profession of optometry has been very successful in providing optical corrections for spherocylindrical refractive errors. In this paper, I examine one attempt to improve retinal image quality beyond that afforded by a standard refractive correction. Ocular chromatic aberration is one of the factors that prevent retinal image quality from reaching the upper limit set by the wave nature of light. It can be subdivided into three primary aberrations (wavelength-dependent differences in imaging plane, image position, and image size). We have been able to measure all three of these using psychophysical techniques. Although attempts to provide an optical correction for wavelength-dependent refractive errors have been optically successful, they have failed to improve vision. Several possible explanations are given for this failure.

Awards and Prizes↗
PubMed1992

Estimation of dioptric power from measurements of meridional power and curvature, sagitta, lens thickness, and prismatic effect.

A method published elsewhere for estimating dioptric power from meridional measurements is generalized here to allow for measurements of sagitta, lens thickness, and prismatic effect as well. Measurements may be of only one type or of combinations of types. Any number of measurements may be used. Within the usual limitations of first-order optics the method always works and gives all solutions when solutions exist. When no solutions exist it gives approximate solutions called least-squares estimates. At least one least-squares estimate always exists. A wide class of ostensibly distinct problems reduces to a single standard routine that is easy to execute with matrix-handling software. If there is reason to believe that the dioptric power is of some particular form then constrained estimation may be applied to find that form.

Eyeglasses↗
PubMed1992

Influence of power changes in single cut rigid contact lenses on tear pump efficiency.

Differences between corneal oxygen uptake rates measured after 5 min of static (without blinking) and 5 min of dynamic (with blinking once every 5 s) non-gas permeable (polymethyl methacrylate) contact lens wear, referenced to the oxygen uptake rates of the normal open eye, were used as indications of tear pump efficiencies associated with each of seven contact lens back vertex powers (-9.00 to +9.00 D, in 3.00 D steps). Measurements were made in vivo on six human corneas showing with-the-rule (0.25 to 0.87 D) toricity. Lens overall diameter was 8.8 mm, optic zone diameter was 7.4 mm, and base curve radius was fitted "on K." Lens center thickness was 0.14 mm for all minus-powered lenses, and 0.19, 0.26, 0.34, and 0.41 mm for the plano, +3.00, +6.00, and +9.00 D lenses, respectively, maintaining an edge thickness of 0.11 mm. Under both static and dynamic wearing conditions, no significant differences were found among the corneal oxygen uptake rates associated with the various contact lens back vertex powers; however, the difference between the static and dynamic condition data, an indication of tear pump efficiency, was greatest for the -3.00 D lens. The difference values associated with the +9.00 and +6.00 D lenses were significantly lower than those associated with the minus power lenses.

Adult↗
PubMed1992

Efficacy and stability of amblyopia therapy.

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.

Adolescent↗
PubMed1992

To use or not to use the refractive correction along with hand-held magnifiers.

Equivalent viewing power (EVP), field of view, and working distance (WD) were calculated for 4 different magnifier equivalent powers, four magnifier-to-eye distances, and for uncorrected spherical ametropias varying from +20.00 to -20.00 D in 0.25 D steps. Results show that the various viewing conditions which arise (depending on whether or not the refractive correction is worn) can differ considerably. The uncorrected unaccommodating myope has a greater EVP than the equivalent power of the magnifier if he chooses a magnifier-to-eye distance shorter than the focal length of the magnifier. In this situation, field of view is also enhanced. The uncorrected unaccommodating hyperope using a magnifier-to-eye distance longer than the focal length of the magnifier achieves a stronger EVP than the equivalent power of the magnifier. However, field of view is then reduced. For the uncorrected unaccommodating spherical ametrope, the use of a magnifier-to-eye distance corresponding to the focal length of the magnifier seems to be a good compromise between EVP, field of view, and working distance.

Eyeglasses↗