OBJECTIVES: There has been continuous development in the area of stereoscopic medical imaging devices, and many stereoscopic imaging devices have been realized and applied in the medical field. In this article, we review past and current trends pertaining to the application stereo-imaging technologies in the medical field. METHODS: We describe the basic principles of stereo vision and visual issues related to it, including visual discomfort, binocular disparities, vergence-accommodation mismatch, and visual fatigue. We also present a brief history of medical applications of stereo-imaging techniques, examples of recently developed stereoscopic medical devices, and patent application trends as they pertain to stereo-imaging medical devices. RESULTS: Three-dimensional (3D) stereo-imaging technology can provide more realistic depth perception to the viewer than conventional two-dimensional imaging technology. Therefore, it allows for a more accurate understanding and analysis of the morphology of an object. Based on these advantages, the significance of stereoscopic imaging in the medical field increases in accordance with the increase in the number of laparoscopic surgeries, and stereo-imaging technology plays a key role in the diagnoses of the detailed morphologies of small biological specimens. CONCLUSIONS: The application of 3D stereo-imaging technology to the medical field will help improve surgical accuracy, reduce operation times, and enhance patient safety. Therefore, it is important to develop more enhanced stereoscopic medical devices.
Asthenopia ; Depth Perception ; Diagnostic Imaging ; Laparoscopy ; Patient Safety ; Vision Disparity ; Vision, Ocular

OBJECTIVETo evaluate the rule of the rebuilding of binocular vision after surgery in strabismus for thyroid-associated ophthalmopathy.

METHODThe binocular vision was examined and compared in 30 patients before and after strabismus surgeries.

RESULTSThe strabismus degrees were 20-80(delta) before surgeries and 2-12(delta) after surgeries. As shown by synoptophores examinations, 19 patients (63.3%) had degree one before strabismus surgeries and the number increased to 28 (93.3%) after the surgeries. Synoptophore fusion area was 0-12(0) [mean (6.1 +/- 4.7)0] before strabismus surgeries and was 0-30(0) [mean (14.4 +/- 5.1)0] after the surgeries (P < 0.001). Nine patients (30%) had stereovision before strabismus surgeries, and the number increased to 22 (73.3%) after the surgeries. Pre-surgery stereoacuity was as follows: none < or = 60", 2 patients 80-200", and 4 patients 300-800"; while the post-surgery stereoacuity was as follows: 4 patients < or = 60", 6 patients 80-200", and 10 patients 300-800" (P < 0.05).

CONCLUSIONStrabismus surgeries for thyroid-associated ophthalmopathy can effectively improve ocular movement and rebuilt binocular vision.

Eye Movements ; Graves Ophthalmopathy ; surgery ; Humans ; Strabismus ; surgery ; Vision Disparity ; Vision, Binocular ; Visual Acuity

When the oculomotor nerve is completely paralyzed, the affected eye shows severe outward displacement and poor cosmetic appearance. Past results of many surgical procedures for oculomotor palsy have been generally unsatisfactory. We tried a new surgical approach experimentally, in which the disinserted lateral rectus muscle was used as an adductor by medial transposition of the muscle. Five adult cats underwent disinsertion of the medial rectus muscle of both eyes to induce iatrogenic medial rectus paralysis. The disinserted medial rectus was removed as far back as possible to prevent reattachment. Then, the right lateral rectus muscle was disinserted and passed beneath the superior rectus muscle and resutured to the sclera 4mm superoposterior to the medial rectus insertion site. After excision of the bilateral medial rectus, a large exotropia of an average 47.6 delta (42.0-55.5 delta) was induced. The medial transposition of the right lateral rectus produced an average 36.6 delta (24.8-45.8 delta) correction of the exotropia. A satisfactory cosmetic result was achieved by this procedure.
Animals ; Cats ; Exotropia/etiology ; Oculomotor Muscles/*surgery ; Oculomotor Nerve Diseases/physiopathology/*surgery ; Vision Disparity

A clinical study on the AC/A ratio with 125 normal persons was performed by modified gradient method. AC/A ratio is a convergence response of an individual to a unit stimulus of accommodation. Through many studies on the AC/A ratio, the normal range of the AC/A ratio was 3 delta/D ~ 5 delta/D. The AC/A ratio can be changed by some drugs. The AC/A ratio is high in divergence excessive exotropia, pseudodivergence exotropia and non-refractive accommodative esotropia; on the other hand, the AC/A ratio is low in convergence insufficiency exotropia. Methods for the determination of the AC/A ratio are heterophoria method, gradient method, fixation disparity method. This study was performed by modified gradient method due to easy application. The mean of the AC/A ratios in this study was 4.55 delta/D, and the AC/A ratios ranged from 0.5 delta/D to 9.6 delta/D. 95 percentile ranged from 3.01 delta/D to 6.09 delta/D. The AC/A ratio in this study seems not to be correlated with age, sex and interpupillary distance.
Esotropia ; Exotropia ; Hand ; Humans ; Ocular Motility Disorders ; Reference Values ; Vision Disparity

A clinical study on the AC/A ratio with 125 normal persons was performed by modified gradient method. AC/A ratio is a convergence response of an individual to a unit stimulus of accommodation. Through many studies on the AC/A ratio, the normal range of the AC/A ratio was 3 delta/D ~ 5 delta/D. The AC/A ratio can be changed by some drugs. The AC/A ratio is high in divergence excessive exotropia, pseudodivergence exotropia and non-refractive accommodative esotropia; on the other hand, the AC/A ratio is low in convergence insufficiency exotropia. Methods for the determination of the AC/A ratio are heterophoria method, gradient method, fixation disparity method. This study was performed by modified gradient method due to easy application. The mean of the AC/A ratios in this study was 4.55 delta/D, and the AC/A ratios ranged from 0.5 delta/D to 9.6 delta/D. 95 percentile ranged from 3.01 delta/D to 6.09 delta/D. The AC/A ratio in this study seems not to be correlated with age, sex and interpupillary distance.
Esotropia ; Exotropia ; Hand ; Humans ; Ocular Motility Disorders ; Reference Values ; Vision Disparity

It is the aim of studies in cognitive process to understand how the impressive cognitive capacity of the human mind is uninterruptedly developed and how the process is controlled. We have been focusing attention on the central question with stereoscopic research. A multi-channel EEG data acquisition system is constructed for cognition studies which not only works perfectly in the EEG collection and signal processing of stereoscopic visual evoked potentials(VEP) but also is suitable for investigative and clinical use. We have identified the fact that the processing of stereoscopic depth information is done in the cortical advance functional areas with labeled characteristic signaling of the depth related VEP and the results were shown to be of no difference when compared with the ones of other investigations. We believe, the stereoscopic depth cognition is both a dynamic multi-factor processing process and a consequence of depth perception in advanced cortical areas through biological feedback to the whole process of visual signal processing. It is our novel and significant supposition in the psychophysical study, and the experimental results of the VEP are presented in this article.
Adult ; Cognition ; Electroencephalography ; instrumentation ; Evoked Potentials, Visual ; physiology ; Humans ; Male ; Signal Processing, Computer-Assisted ; instrumentation ; Vision Disparity ; physiology ; Visual Cortex ; physiology

PURPOSE: To investigate horizontal image disparity in three-dimensional (3-D) perception using 3-D animations in normal control patients and patients with intermittent exotropia, anisometropic amblyopia, and partially accommodative esotropia. MATERIALS AND METHODS: A total of 133 subjects were included. Stereopsis was measured using the Titmus Stereo test (Stereo Optical Inc., Chicago, IL, USA) and a 3-D stereopsis test with a 15 inch 3-D display laptop, adjusting 3-D parameters of 0 mm horizontal disparity to 15 mm horizontal disparity. RESULTS: When compared with normal controls, the average threshold of the 3-D stereopsis test was significantly reduced for esotropia patients (p<0.001) and for anisometric amblyopia patients (p<0.001), compared to normal controls. No significant difference was observed between normal controls and intermittent exotropia patients (p=0.082). The 3-D stereopsis test was correlated with the Titmus Stereo test (Spearman's rho=0.690, p<0.001). Mean difference in stereoacuity was 1.323 log seconds of arc (95% limits of agreement: 0.486 to 2.112), and 125 (92.5%) patients were within the limits of agreement. CONCLUSION: This study demonstrated that a 3-D stereopsis test with animation is highly correlated with the Titmus Stereo test; nevertheless, 3-D stereopsis with animations generates more image disparities than the conventional Titmus Stereo test. The 3-D stereopsis test is highly predictive for estimating real stereopsis in a 3-D movie theater.
Adult ; Aged ; Amblyopia/diagnosis ; Anisometropia/diagnosis ; *Depth Perception ; Esotropia/diagnosis ; Female ; Humans ; Imaging, Three-Dimensional/*instrumentation ; Male ; Middle Aged ; *Perceptual Disorders ; Software ; *Vision Disparity ; Vision, Binocular ; Visual Acuity/*physiology