Monocular Clues Research Articles

Computer vision-based system for early diagnosis of stereoscopic vision alterations

ABSTRACT Stereopsis is the three-dimensional perception capability, which is possible when binocular vision is present. Development of binocular vision system ends around 7-year-old, and after this time brain connections are already set, therefore, it will be difficult to recover stereopsis. Early diagnosis of Stereoscopic Visual Alterations (SVA) in the childhood is paramount to receive an appropriate treatment as soon as possible. Currently, to detect SVA, ophthalmologists commonly carry out tests based on cards. All these tests are based on the random-dot-stereogram principle, with different seconds of arc images, which allows doctors to graduate stereopsis. Some limits of this tests have been identified, such as monocular clues (e.g., the contours of the objects), or the non-standardized range levels depending on the test. This paper presents a novel concept of measuring stereopsis based on computer vision techniques. The system detects SVA in patients and calculates the degree of the perceived depth. As early diagnosis of SVA may suppose a therapeutic possibility, this platform is aimed at children by using stereoscopic models with varied and attractive designs. To validate the proposal, an early-stage prototype has been implemented and an objective evaluation of the measurement accuracy and reliability has been carried out with satisfactory results.

Comparison of the Efficacy of TNO and Titmus Fly in Myopic Anisometropes

Objectives: The aim of this study is to evaluate the stereo acuity in anisometropic myopes and to compare efficacy of TNO and Titmus fly test. Methodology: The cross sectional study design was carried out from September 2021 to May 2022 at eye departments of different teaching hospitals of Punjab. A total study sample of 150 subjects age range between 11-33 years of both gender (male and female) having myopic anisometropia (with moderate and severe degree of anisometopia) were included in this study. All other types of refractive error except myopic anisometropes, all ocular pathologies and systemic pathologies were excluded from the study. After taking informed consent from the individual’s subject to undergo routine ophthalmological examinations, including slit lamp examination of the inner and posterior chamber of the eye and best corrected visual acuity of both eyes (BCVA). Steroacuity test TNO and Titmus were performed to evaluate the stereopsis of myopic anisometropes. Data analysis was done by SPSS version 20. Independent sample t test was used for statistically analysis. Results: Results showed that stereopsis gets reduced by myopic anisometropia. As the level of anisometropia increase from 1D and above, the stereopsis deteriorates in case of myopic anisometropia Conclusion: TNO is considered more reliable as compared to Titmus fly test as the level of difficulty is more in TNO and is independent of monocular clues. Keywords: Depth perception, Myopic anisometropes, TNO test, Titmus stereoacuity test.

Elucidation of the mechanism of stereoscopic insufficiency and mental and physical fatigue caused by near vision - research and development on recovery methods

Increased exposure to video terminal display (VDT) devices is part of 21st century life, but the consequences of this are myopia and abnormal binocular single vision, which present as mental and physical fatigue. A collaborative team is investigating the mechanism underlying abnormal binocular single vision and developing a methodology for recovery. Associate Professor Satoshi Takahashi, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Japan, and the tem are looking into the interaction between binocular stereoscopic clues and monocular stereoscopic clues in binocular single vision. Their goal is to explore the effects on depth judgment and the researchers will use their findings to construct a training system that enables correct depth judgement in binocular single vision. This extensive research will involve conducting inspections on a large number of participants and developing effective methods for inspecting binocular stereoscopic function. This will lead to the development of a device that can easily diagnose the binocular stereoscopic function of the participants and enable early detection. Takahashi and the team will also explore training methods that can help individuals recover lost eye function and encourage behavioural changes that will reduce incidence of eye problems.

Effect of Planting Design in Changing Architectural Perception in Landscape

The study deals with architecture and plant relations, aims to help the landscape designers to achieve integration between architecture and planting design of surrounding landscapes in accordance to the designer desire. The study also deals with employing planting design in changing architectural perception through changing its dimensions to be more horizontal or vertical and changing depth perception to be more closer or far from the viewer. The study aims at adopting a theoretical framework for the illusion phenomena to be employed in planting design in order to change architectural perception. This is done through using physiological phenomena related to eye and optical deviations in addition to using gestalt theory laws represented by proximity, continuity and direction , illusion properties for monocular and binocular clues, light and color formation clues, texture pattern formation and perspective clues. Keywords : architecture , plant ,landscape , perception , illusions

Monocular Clues in Seven Stereotests

Purpose: There have been numerous reports with evidence detailing the presence of non-stereoscopic or “monocular”clues in commonly used stereoacuity tests. The purpose of this study was to quantify the influence of monocularclues in the Titmus, Randot®, Randot® Special Edition, Randot® Preschool, Lang, Lang II, and Frisby stereoacuitytests. Stereoacuity testing is typically performed and/or interpreted by eye care professionals and other health/occupational professionals. Methods: Two separate prospective studies were conducted. The first assessed the monocular responses of 100subjects aged 8 to 67 with normal stereoacuity, and no previous exposure to any of the seven tests administered.The second assessed the monocular responses of 33 subjects aged 8 to 65 with longstanding, manifest, horizontalstrabismus of 20 prism diopters or greater, on the aforementioned stereotests. Results: Monocular clues were found to be present for the normal group on the Titmus (61%), Randot® (6%), Randot®Special Edition (5%), Randot® Preschool (7%), Lang (13%), and Lang II (37%). Monocular clues were found to be presentfor the strabismic group on the Titmus (100%), Randot® (9%), Randot® Special Edition (9%), Randot® Preschool (12%),Lang (3%), and Lang II (27%). There was no monocular identification for either group on the Frisby stereotest, butthere was minimal binocular identification by a subject with manifest strabismus. Conclusion: Monocular clues were present for both the normal and strabismic group on 6 of the 7 stereotestsinvestigated. Based on these findings the authors conclude that caution must be used when interpreting patientresponses on the 7 aforementioned stereotests.

The role of the random dot Stereo Butterfly test as an adjunct test for the detection of constant strabismus in vision screening

A goal of vision screening is the detection of amblyopia risk factors, including strabismus. The random dot Stereo Butterfly test requires no instruction, has a simple pass/fail response with no monocular clues, and is easily administered. The purpose of this study was to determine whether this test could be used as a cost-effective and reliable component of preschool vision screening. The Stereo Butterfly was presented to children with no previous history of ocular problems or treatment. The test was presented with the use of polarized glasses at a 16-inch testing distance. A "pass" was recorded if the patient reported seeing a butterfly; a "refer" was denoted otherwise. Vision and motility measurements were recorded, and the patient underwent a complete eye examination with cycloplegic refraction. A total of 281 children 3 to 6 years of age were tested: 221 children passed the test. Of those who passed, 7 (3.2%) had intermittent strabismus, 1 had a small-angle constant strabismus, 60 failed screening for constant strabismus (of whom 24 [40%] had constant strabismus), and 6 were false-negative results. The sensitivity of the Stereo Butterfly for detecting constant strabismus was 96%; the specificity, 86%. The Stereo Butterfly test may be a valuable adjunctive tool in vision screening programs for the detection of manifest strabismus because it is easy to administer and effectively detects constant strabismus. It has a high specificity for detection of constant strabismus but, if used alone, the low positive predictive value would allow for many false-positive results.

Maximum angle of horizontal strabismus consistent with true stereopsis

BackgroundWe prospectively evaluated the performance of three stereoacuity tests in patients with a wide range of strabismus angles to determine the maximum angle of horizontal strabismus consistent with true stereopsis as well as the extent of false-positive results. MethodsSubjects age ≥ 5 years old (n = 186) with constant horizontal strabismus were prospectively studied. Stereoacuity was measured using the Titmus Fly, Animals, and Circles tests; the original Preschool Randot test; and the Frisby test. We defined a false-positive result as any positive response to a stereoacuity test when a patient had > 20 prism diopters (PD) of deviation. Based on the results from our previous study of monocularly patched adults, we then defined a true-positive result as Titmus circles five to nine, at least 400“ on the original Preschool Randot test, or a pass on the Frisby test. Data were then analyzed to determine a maximum deviation consistent with true stereopsis. ResultsFalse-positive results occurred with Titmus Fly (6%), Titmus Animals (10%), Titmus Circles (35%), and the 800 seconds of arc (”) level of the original Preschool Randot test (10%). No false-positive results were seen with the Frisby test. Applying the criteria for a true-positive result, we found that no patient with > 10 PD of deviation had true stereopsis. The two patients with 10 PD and 6 PD deviations could not subsequently pass the Frisby test and were therefore deemed not to have true stereopsis. We concluded that the threshold for true stereopsis may be as low as 4 PD of horizontal deviation. ConclusionIn summary, the Titmus Fly, Titmus Animals, and Titmus Circles (the first four circles) tests possess monocular clues that limit their usefulness for clinical testing. The Frisby test is particularly useful for rapid assessment of whether stereopsis is present or absent. The new Preschool Randot test is valuable for quantifying stereopsis in both children and adults. True stereopsis may be rare when a patient has a horizontal deviation > 4 PD.

Postoperative stereoacuity following realignment for chronic acquired strabismus in adults

Background: There is controversy regarding whether or not visually mature individuals can permanently lose stereoacuity and under what conditions stereoacuity can be regained. Some have proposed a critical duration of misalignment in adults beyond which recovery of fine stereoacuity is not possible, despite successful surgical alignment. Methods: Twenty-one adult patients (median age 59 years) with large-angle acquired strabismus and who were successfully surgically aligned after 7 to 501 months of misalignment were studied. Subjects had no evidence of motor or sensory fusion since the onset of strabismus, on preoperative exam, or by history. Stereoacuity was measured using 1 or more of the Frisby, Preschool Randot and Titmus tests, at 8 weeks and at 12 months. Data from tests with monocular clues were not used. Results: At total of 67% of patients with chronic acquired strabismus and no preoperative fusion regained measurable stereoacuity and 44% regained fine stereoacuity of at least 60 seconds of arc. Of 10 patients with no or subnormal stereoacuity 8 weeks postoperatively, 6 (60%) showed improvement at the 12-month visit. Misalignment for up to 4 years did not preclude the development of postoperative stereoacuity. Conclusions: Although a minority of adult strabismus patients may permanently lose stereoacuity despite successful alignment for acquired strabismus, the majority do show recovery. Such recovery of stereoacuity may take several months to occur. In our adult series, duration of misalignment did not predict failure to recover stereoacuity. (J AAPOS 2002;6:233-7)

The Goldmann Memorial Lecture--historical and current aspects of stereopsis

According to Goldmann stereopsis is the highest performance of binocular recognition. A historical review shows that binocular stereopsis was explained only in 1838 by Wheatstone, whereas the monocular clues for stereopsis e.g. size, position and covering of the objects, light and shadow, perspective of the air, parallax and linear perspective were known long ago. The denomination depth perception is ambiguous: "depth" is the opposite of "height". Stereopsis means natural recognition of distance and objects in space, stereoscopy means recognition by the aide of an instrument. Natural and dichoptic stereopsis and the influences of vertical structures, of pupillary distance and of astigmatism are discussed. Examination of stereopsis is discussed, among others the two pencil test, the stereo-modification Bagolini-glasses, the combination of the plano-cylinders of W. R. Hess with random dots without glasses, the disk stereopsis etc. Goldmann's theory of binocular vision helps to understand different forms of strabismus, e.g. the statistical interplay of fixation and fusion for microtropia, the fixation mechanism for the congenital strabismus syndrome, the use of binocular stereopsis only for near explains intermittent divergence.

Stereoacuity Testing in the Monofixation Syndrome

A group of patients with the monofixation syndrome were assessed prospectively to compare performance on Titmus and Randot stereograms under monocular and binocular conditions. These patients achieved monofixation either as a result of surgery for infantile esotropia, or because of a partially accommodative esotropia or significant anisometropia. Their ability to detect elevation of the Titmus circles was not significantly better with two eyes as compared to that level achieved using only their monofixating eye. However, performance on the Titmus animals and on Randot circles or animals showed better discrimination. These data would suggest that the monocular clues available in determining elevation of the Titmus circles would invalidate establishing a diagnosis of monofixation.

Toward the design of an optimal filter for enhancement of dichromat monocular chromatic discrimination.

Based on Farnsworth's theories of color confusion and discrimination, "rose-colored" or "pink" filters such as the X-Chrom material of 0.16 mm in thickness or the Kodak Wratten no. 30 filter act as monocular chromatic enhancers for red/green color deficients by virtue of colorimetrically lengthening color space in a direction perpendicular to the dichromatic axis of color confusion. Using derived formulas for dichromat colorimetry, a set of representative isoluminant-isochroma spectral hues, and interactive computer graphic colorimetric tools, it is possible to determine an optimum spectrophotometric filter curve. Such a filter has minimal middle wavelength transmission and is optimal in terms of providing maximal monocular chromatic clues for discriminative tasks involving confused colors.

Strabismus Surgery and Its Effect Upon Infant Development in Congenital Esotropia

Parents of children with congenital esotropia have reported improvements in their child's fine motor development and visual functions after surgery. Eighteen patients with congenital esotropia were tested pre- and post-operatively with The Bayley Scales of Infant Development to determine if these observations were valid. A three-point increase in the Bayley raw score of strabismus patients was noted after operation that is significant at the 0.01 level, as compared to the performance of age-matched controls. An improvement in fine motor skills was observed in 35% of the children, and visually directed reaching and grasping increased in 41%. Item #87 on the Bayley, which requires the child to recognize depressions without monocular clues, appears to be related specifically to depth perception. On this item, the study population showed the greatest improvement.

Binocular-disparity-dependent upper-lower hemifield anisotropy and left-right hemifield isotropy as revealed by dynamic random-dot stereograms.

Dynamic random-dot stereograms devoid of all monocular depth cues were used to measure the limits of temporal and spatial resolution in the center of the visual field. The temporal durations for detecting a small, briefly presented test square of different binocular disparity than the surround varied as a function of its location and binocular disparity. The test squares presented in the upper hemifield were detectable at consistently shorter durations than those presented in the lower hemifield for a surround disparity which was uncrossed relative to the fixation marker. For crossed surround disparity this preference reversed, resulting in a superiority of the lower hemifield. The anisotropy diminished for zero surround disparity. No such anisotropy was found when left and right visual hemifields were compared. It was also shown that this upper-lower temporal anisotropy (and left-right isotropy) is paralleled by a similar disparity-dependent upper-lower anistropy (and left-right isotropy) in spatial resolution. Introduction of monocular clues into the stereograms tended to eliminate the anisotropies. This implies that the anisotropies reflect the spatiotemporal properties and distribution of binocular disparity detectors in the human cortex and result in a tilted surface that pivots around the horizontal midline in the space of binocular depth perception.

Effect of monocular and binocular vision in vehicle driving speeds.

By testing driving performance under binocular viewing conditions and under monocular viewing conditions, the authors make a comparison of the effectiveness of binocular and monocular clues.

STEREOSCOPIC VISION APPLIED TO PHOTOGRAMMETRY

ABSTRACTIn Part I the visual processes involved in depth perception are briefly described and discussed, while in Part II their application in stereo plotting and allied observations is considered. Reference is made to the visual axis, the need for and nature of eye movements, the conception of the horopter space within which fusion of the binocular images occurs and objects are seen in three‐dimensions, and the tolerances for fusion implied by the existence of Panum's areas. Monocular clues make an important contribution to the perception of depth, and the apparent location of an object in space is determined by the factors of retinal disparity, convergence, angular size, perspective, motion parallax, elevation, aerial haze, etc. The following problems are then discussed: The significance of the horopter in relation to the general contour in a stereo photograph; the fusion of the images in a stereo plotting machine; the arguments for and against some convergence of the eyepiece axes; the special problems of spectacle wearers; the functions of field stop. An analysis of the visual task in contour plotting is attempted, but a more complete analysis would be possible if records were available of the observer's eye movements while plotting. Finally, chromatic aberration in relation to the Multiplex system is considered, and also in connection with the stereoscopic effect observed with differently coloured objects lying in a plane.