Previous studies have proposed two cognitive mechanisms responsible for the Ebbinghaus illusion effect, i.e., contour interaction and size contrast. However, the neural underpinnings of these two mechanisms are largely unexplored. The present study introduced binocular depth to the Ebbinghaus illusion configuration and made the central target appear either in front of or behind the surrounding inducers in order to disturb size contrast instead of contour interaction. The results showed that the illusion effect, though persisted, was significantly reduced under the binocular depth conditions. Notably, the target with a larger perceived size reduced early alpha-band power (8-13 Hz, 0-100 ms after stimulus onset) at centroparietal sites irrespective of the relative depth of the target and the inducers, with the parietal alpha power negatively correlated with the illusion effect. Moreover, the target with a larger perceived size increased the occipito-parietal beta-band power (14-25 Hz, 200-300 ms after stimulus onset) under the no-depth condition, and the beta power was positively correlated with the illusion effect when the depth conditions were subtracted from the no-depth condition. The findings provided neurophysiological evidence in favor of the two cognitive mechanisms of the Ebbinghaus illusion by revealing that early alpha power is associated with low-level contour interaction and late beta power is linked to high-level size contrast, supporting the claim that neural oscillations at distinct frequency bands dynamically support different aspects of visual processing.
Humans ; Alpha Rhythm/physiology* ; Female ; Male ; Size Perception/physiology* ; Young Adult ; Adult ; Beta Rhythm/physiology* ; Photic Stimulation/methods* ; Illusions/physiology* ; Optical Illusions/physiology* ; Depth Perception/physiology*

In this study, we explored the neural mechanism underlying impaired stereopsis and possible functional plasticity after strabismus surgery. We enrolled 18 stereo-deficient patients with intermittent exotropia before and after surgery, along with 18 healthy controls. Functional magnetic resonance imaging data were collected when participants viewed three-dimensional stimuli. Compared with controls, preoperative patients showed hypoactivation in higher-level dorsal (visual and parietal) areas and ventral visual areas. Pre- and postoperative activation did not significantly differ in patients overall; patients with improved stereopsis showed stronger postoperative activation than preoperative activation in the right V3A and left intraparietal sulcus. Worse stereopsis and fusional control were correlated with preoperative hypoactivation, suggesting that cortical deficits along the two streams might reflect impaired stereopsis in intermittent exotropia. The correlation between improved stereopsis and activation in the right V3A after surgery indicates that functional plasticity may underlie the improvement of stereopsis. Thus, additional postoperative strategies are needed to promote functional plasticity and enhance the recovery of stereopsis.
Humans ; Exotropia/surgery* ; Depth Perception/physiology* ; Strabismus/surgery* ; Oculomotor Muscles/surgery*

PURPOSE: The purpose of this study was to evaluate whether eye dominance changes after conventional pseudophakic monovision, and to identify factors that affect changes in eye dominance. METHODS: This retrospective study included 70 patients who underwent bilateral conventional monovision cataract surgery. Patients were divided into two groups based on whether they experienced a change in the dominant eye. We compared patients' uncorrected distance visual acuity (UCDVA), uncorrected near visual acuity (UCNVA), best-corrected visual acuity (BCVA), spherical equivalent, stereopsis, and time interval between cataract surgeries. RESULTS: The mean age was 71.26 ± 10.84 (range, 25–90) years, mean interval between surgery in each eye was 118.46 ± 183.50 (range, 17–1,018) days, and mean postoperative diopter difference was 1.16 ± 0.53 (range, 0.00–2.75) diopters. After bilateral cataract surgery, 22 patients (31.43%) experienced a change in eye dominance, whereas 48 patients (68.57%) experienced no change. There were no differences in the time interval between cataract surgeries, preoperative UCDVA and UCNVA, pre- and postoperative BCVA, or stereopsis in either group. Patients who experienced a change in eye dominance showed smaller differences between preoperative and postoperative spherical equivalent, compared with patients who experienced no change in eye dominance (t-test, p < 0.05). CONCLUSIONS: Twenty-two (31.43%) patients whose nondominant eyes were targeted for near vision showed altered eye dominance after conventional monovision cataract surgery. Eye dominance shows greater plasticity in patients with smaller differences between preoperative and postoperative spherical equivalent.
Cataract ; Clinical Study ; Depth Perception ; Dominance, Ocular ; Humans ; Plastics ; Presbyopia ; Retrospective Studies ; Visual Acuity

PURPOSE: To analyze stereopsis change before and after inferior oblique weakening surgery. METHODS: We retrospectively reviewed the medical records of 31 patients who had undergone inferior oblique weakening surgery. The factors analyzed included sex, age at surgery, preoperative and postoperative visual acuity (VA), time from first detection to surgery, degree of inferior oblique overaction (IOOA), primary/secondary IOOA, exotropia/hypertropia, bilaterality, and type of surgery. RESULTS: Eighteen patients with a mean age 7.3 ± 3.1 years exhibited stereopsis of 60 arc seconds or better before surgery and 17 had stereopsis better than 60 arc seconds after surgery. Postoperatively, stereopsis improved in 13 patients and deteriorated in 9. Better preoperative VA and the absence of superior oblique underaction were associated with better preoperative stereopsis. Better preoperative VA, postoperative VA, and the presence of head tilt were associated with better postoperative stereopsis. Unilateral inferior oblique weakening surgery and accompanying hypertropia were associated with improved stereopsis, while the absence of hypertropia was associated with deteriorated stereopsis. CONCLUSIONS: In this retrospective study, 58.1% of patients tended to have bifoveal fixation. When a vertical deviation is present in the primary position due to unilateral IOOA, IO weakening surgery can be expected to improve binocular function.
Depth Perception* ; Head ; Humans ; Jupiter ; Medical Records ; Retrospective Studies ; Strabismus ; Telescopes ; Visual Acuity

PURPOSE: To determine the amount of additional surgery required for patients with consecutive esotropia, who had an esodeviation angle similar to their pre-operative exodeviation angle, following bilateral lateral rectus recession surgery for intermittent exotropia. METHODS: The medical records of 29 patients who underwent surgery for intermittent exotropia from 1998 through 2013 were reviewed. These patients had consecutive esotropia with an unchanged postoperative esodeviation angle. Thirteen patients underwent esotropia surgery with the aim of full correction (Group A), while 16 patients underwent esotropia surgery with the aim of partial correction (Group B). The postoperative ocular alignment and stereopsis of both groups were compared. RESULTS: A total of 29 patients were evaluated including 13 patients in Group A and 16 patients in Group B. At the final follow-up visit, at least 24 months post procedure, Group B had a significantly greater success rate than Group A (62.5% vs. 23.1%, p = 0.039). Over-correction rates were higher in Group A than Group B (76.9% vs. 37.5%, p = 0.039). The changes during the follow-up period (6 months to their last follow-up) showed that the over-correction rate had increased from 30.8% to 76.9% in Group A (p = 0.034) and from 12.5% to 37.5% in Group B (p = 0.046). CONCLUSIONS: Consecutive esotropia surgery with the aim of partial correction showed favorable motor and sensory outcomes in patients who had a postoperative esodeviation angle similar to that of their pre-operative exodeviation. This strategy may also be helpful in preventing long-term postoperative over-correction in patients presenting with consecutive esotropia.
Depth Perception ; Esotropia ; Exotropia ; Follow-Up Studies ; Humans ; Medical Records

PURPOSE: To evaluate the relationship between initial postoperative overcorrection and long-term surgical success in exotropia patients. METHODS: The medical records of 46 patients who underwent surgery for intermittent exotropia after the age of 18 were enrolled. Enrolled patients also had at least 2 years of postoperative follow-up. Based on the initial postoperative deviation at distance measured by prism and the alternating cover test at 1 week, patients were assigned to one of the following groups: group A included patients who demonstrated any esodeviation, while group B included patients who showed orthophoria to exodeviation of 10 prism diopters. The records were analyzed to determine the preoperative deviation with stereoacuity and postoperative deviations with stereoacuity at the follow-up examinations at the following intervals: 1 week; 1, 3, and 6 months; and 1 and 2 years. A comparison between groups for demographic data and preoperative and postoperative angles of deviation was performed using analysis of variance. RESULTS: Of the 46 patients with intermittent exotropia included in this study, 18 (39%) belonged to group A, while 28 (73%) belonged to group B. The postoperative angle of deviation for distant fixation until 2 years of follow-up showed statistically significant differences in each group (p < 0.003 in all comparisons). The amount of exodrift until 2 years in group A (from −9.7 ± 6.1 to 1.6 ± 3.7) was greater than that in group B (from 2.0 ± 2.7 to 6.8 ± 5.6). The long-term surgical success rate within 2 years of surgery was significantly better in group A than in group B (p = 0.027). The number of patients with intermittent diplopia and the duration of diplopia were greater in group A (n = 8) than in group B (n = 2). CONCLUSIONS: Long-term surgical success was achieved in 89% of patients who were initially overcorrected. Overcorrection of an average of 10 prism diopters at the first postoperative week was found to be associated with a more favorable long-term surgical outcome.
Adult* ; Depth Perception ; Diplopia ; Esotropia ; Exotropia* ; Follow-Up Studies ; Humans ; Medical Records

PURPOSE: To compare the characteristics of patients with surgically overcorrected intermittent exotropia treated with alternate patching. METHODS: The medical records of 51 patients who underwent bilateral lateral rectus muscle recession for intermittent exotropia and required alternate patching to correct postoperative overcorrection were retrospectively reviewed. Patients with postoperative esodeviation ≥18 prism diopters (PD) were started on alternate patching on postoperative day 1, whereas those with postoperative esodeviation of 10 to 17 PD were started after 2 weeks. Postoperative esodeviation <10 PD was considered as slight intentional overcorrection after exotropia surgery. Patients not responsive to alternate patching treatment were defined as those with postoperative esodeviation ≥10 PD after 3 months of treatment. Sex, family history, age, refractive error, amblyopia, stereopsis, suppression, type of exotropia, surgical method, preoperative and postoperative angle of deviation, and start time of alternate patching were compared. RESULTS: Among 51 patients, 29 patients responded to alternate patching and 22 patients did not respond. Female sex (p = 0.04), larger preoperative exodeviation at distance (p = 0.04), late onset of postoperative maximal esodeviation (p < 0.01), larger postoperative maximal esodeviation at near (p = 0.02), and late initiation of alternate patching (p = 0.01) were associated with patients in the non-responsive group. Although postoperative angle of deviation was similar for 2 weeks, the angle of postoperative esodeviation was significantly larger in the non-responsive group than in the responsive group, beginning at 1 month postoperatively. CONCLUSIONS: Female sex, large preoperative exodeviation, late initiation of alternate patching, and large esodeviation 1-month postoperative predisposed patients to be resistant to alternate patching for postoperative overcorrection.
Amblyopia ; Depth Perception ; Esotropia ; Exotropia* ; Female ; Humans ; Medical Records ; Methods ; Refractive Errors ; Retrospective Studies

Videogames offer the usual skills needed for laparoscopy namely, eye-hand coordination, depth perception, and bimanual operation. The impact of playing videogames on basic laparoscopic skills is still ambiguous with some studies showing correlation and with other studies demonstrating little or no effect.

OBJECTIVE: To determine the impact of training with Nintendo® WiiTM in the improvement of basic laparoscopic skill among laparoscopic novices by measuring the time to completion of eye-hand coordination task, two-hand manipulation task, grasping and cutting task or grasping and clipping tasks.

METHODS: An electronic systematic search was done in online databases and search engines. This review included randomized prospective studies, written in English language, and published within the last 5 years. Participants included adults 19-29 years old, medical students and surgical residents, with a low video game experience, without or minimal experience in laparoscopic surgery and laparoscopic simulator. The studies compared the performance of participants in a laparoscopic simulator (SimbionixTM LapMentorTM or ProMIS) after training with Nintendo® WiiTM and measured their completion time of several tasks.

RESULTS: Training with Nintendo® WiiTM showed improvement in time to completion of eye-hand coordination task, two-hand manipulation task, and grasping and clipping task. The study however showed equivocal results in the grasping and cutting tasks.

CONCLUSION: Training with Nintendo® WiiTM can be used as a training tool for the improvement of basic laparoscopic skills of laparoscopic novices.

Visual conditions such as anisometropia, monovision and monocular undercorrection affect the combination of visual input from both eyes. This study investigated the effects of monocular blur, in binocularly normal participants, on stereoacuity and binocular contrast sensitivity. Fifteen young adults (age range between 19 and 23 years old) with normal visual acuity and binocular vision participated in this study. Stereopsis was measured using the TNO test with a series of positive spherical lenses placed before the dominant eye. The procedure was repeated using the Titmus Stereotest on five participants as a control experiment. Monocular and binocular contrast sensitivities were also measured using the Pelli-Robson Contrast Sensitivity Chart. Blur was induced monocularly with a series of positive spherical lenses placed before the dominant eye and binocular contrast sensitivity was re-measured. Stereopsis scores decreased significantly when monocular blur was imposed. Across blur levels, absolute stereopsis scores measured with TNO test were worse than those measured with Titmus stereotest (all p < 0.05). However, the ratio of scores obtained without blur and under monocular blur appeared to be similar for both tests. Stereopsis without blur was between 6.82× to 8× better than that obtained with the highest level of imposed monocular blur. Binocular contrast sensitivity score decreased significantly with increasing level of monocular blur (p < 0.01). Binocular contrast sensitivity score without blur was 1.62× better than that obtained under binocular viewing with highest level of imposed blur. Stereopsis tests are more sensitive than measurements of binocular contrast sensitivity as an indicator of interocular acuity discrepancies which could occur in anisometropic or monovision patients. However, the choice of stereopsis test is crucial, as the TNO test appears to be more sensitive to monocular blur than the Titmus stereostest.
Depth Perception

PURPOSE: To analyze the effect of stereopsis and contrast sensitivity on the quality of life and to evaluate the relationship between integrated binocular visual field (IVF) and binocular visual function in bilateral normal tension glaucoma (NTG) patients. METHODS: Stereopsis and contrast sensitivity tests were performed and compared among 44 NTG patients and 32 normal subjects. The IVF was integrated using the best location method. The correlation between visual function and subscales of the National Eye Institute Visual Function Questionnaire 25 (NEI VFQ-25) was evaluated using univariate linear regression. RESULTS: Stereopsis and contrast sensitivity for the bilateral NTG patients were decreased compared to the normal controls. Stereopsis and contrast sensitivity exhibited a significant correlation with social functions related to vision and color vision among subscales of NEI VFQ-25. IVF mean deviation (MD) and better eye MD showed a significant correlation with stereopsis and contrast sensitivity, while worse eye MD showed no association. CONCLUSIONS: Deterioration of stereopsis and contrast sensitivity in NTG patients affects their quality of life related to social functions and color vision. Both IVF and better eye MDs are correlated with stereopsis and contrast sensitivity in NTG patients.
Color Vision ; Contrast Sensitivity ; Depth Perception ; Humans ; Linear Models ; Low Tension Glaucoma* ; Methods ; National Eye Institute (U.S.) ; Quality of Life* ; Telescopes* ; Visual Fields