Search Results (11)

Human eyes do not have perfectly aligned optical components; the fovea is displaced from the posterior pole, and the crystalline lens is tilted away from the eye’s optical axis. Important in the study of vision quality, it is included here in binocular and oculomotor research. In the binocular system, with the eye’s optical asymmetry, all axes differ. The eye’s posture change is decomposed into the torsion-free part that gives the change in visual axis direction and the torsional part that best approximates the rotation about the lens’s optical axis. This geometric formulation, supported by computer simulations and modern ophthalmology studies, leads to binocular Listing’s law and the related half-angle rule, important for oculomotor control by constraining the eye’s redundant torsional degree of freedom. The eye’s primary position and the Listing plane, indispensable ingredients of Listing’s law, are replaced with the binocular eyes’ posture corresponding to the eye muscles’ natural tonus resting position, which serves as a zero-reference level for convergence effort. Further, the binocular constraints couple 3D changes in the torsional positions of the eyes within the ab initio formulation of Listing’s law here, which was previously proposed ad hoc. Finally, the noncommutativity rule underlying Listing’s law and the half-angle rule are discussed by specifying the configuration space of sequences of fixations of binocularly constrained eyes, which are visualized in 3D simulations. The results obtained in this study should be a part of the answers to the questions posted in the literature on the relevance of Listing’s law to clinical practices. Full article

Ocular tilt reaction (OTR) and trochlear nerve palsy (TNP) can induce cyclotorsion. We aimed to assess the utility of fundus photography in distinguishing between these disorders. The database of a neuro-ophthalmology hospital-based clinic was retrospectively searched for patients referred for new-onset vertical diplopia between 2020 and 2023. Medical data were collected, and the angle between the optic disc and fovea was measured using ImageJ software to quantify torsion. Distinct torsional patterns were identified between the groups. OTR was characterized by variable, often conjugate torsion, whereas TNP demonstrated consistent disconjugate extorsion. Analysis of interocular torsional relationships, rather than magnitude alone, provided useful diagnostic discrimination. Fundus photography may be useful for differentiating OTR from TNP in complicated neurological cases, particularly in patients who are difficult to examine. This study emphasizes the practical clinical value of fundus photography as a simple, accessible, and objective tool for differentiating OTR from TNP, by contributing the torsional component of OTR triad, particularly in emergency or diagnostically challenging settings where standard examination may be limited. Full article

While typical benign paroxysmal positional vertigo (BPPV) presents with reproducible patterns of nystagmus and vertigo during positional testing, atypical variants often deviate from typical patterns, making diagnosis more complex. Recognizing atypical BPPV is crucial to avoid misdiagnosis and inappropriate management. This study aims to describe the clinical spectrum of atypical BPPV, differentiate it from central positional vertigo, and provide practical diagnostic guidance for clinicians. A narrative review was conducted to explore the clinical spectrum of atypical BPPV. Findings indicate that it may present with vertigo without nystagmus, conflicting torsional components in bilateral cases, or persistent symptoms despite repositioning maneuvers. Canal switch and pseudo-spontaneous nystagmus have also been described. Although these variants may mimic central etiologies, the absence of consistent neurological signs supports a peripheral mechanism. Diagnosis relies on detailed assessment of nystagmus characteristics—such as latency, /duration, and direction—as well as the exclusion of red flags, like direction-changing nystagmus without head movement, vomiting, or non-positional ocular motor abnormalities. Atypical BPPV remains a diagnostic challenge and requires careful bedside assessment and clinical testing. Understanding these variants is essential for timely and appropriate treatment. When doubt persists and resolution with treatment does not occur, neuroimaging should be considered to exclude central pathology. Full article

Sensing gravity through the otolith receptors is crucial for bipedal stability and gait. The overall contribution of the otolith organs to eye movements, postural control, and perceptual functions is the basis for clinical testing of otolith function. With such a wide range of contributions, it is important to recognize that the functional outcomes of these tests may vary depending on the specific method employed to stimulate the hair cells. In this article, we review common methods used for clinical evaluation of otolith function and discuss how different aspects of physiology may affect the functional measurements in these tests. We compare the properties and performance of various clinical tests with an emphasis on the newly developed video ocular counter roll (vOCR), measurement of ocular torsion on fundus photography, and subjective visual vertical or horizontal (SVV/SVH) testing. Full article

This retrospective, observational study examined the surgical outcomes of bilateral inferior rectus (IR) recession in thyroid eye disease. Twelve patients who underwent bilateral IR muscle recession were included in the study. Surgical success was defined as patient achievement of the following conditions: (1) a postoperative angle of vertical ocular deviation of ≤3°; (2) a postoperative cyclotropic angle of ≤2°; (3) postoperative binocular single vision, including the primary position; and (4) postoperative enlargement of the field of binocular single vision. Linear regression analyses were performed to analyze the relationship between postoperative changes in the vertical and torsional ocular deviation angles and the amount of IR muscle recession and nasal transposition. Consequently, 9 out of 12 patients were deemed to have had successful surgical outcomes. There was a positive correlation between a change in the vertical deviation angle and a side-related difference in the amount of IR muscle recession in successful cases (crude coefficient, 2.524). A positive correlation was also found between a change in the torsional deviation angle and the amount of IR recession (crude coefficient, 1.059) and nasal transposition (crude coefficient, 5.907). The results will be helpful to more precisely determine the amount of recession and nasal transposition of the IR muscle in patients with thyroid-related bilateral IR myopathy. Full article

Purpose: To report the rate of ocular torsion in children with horizontal strabismus or orthophoria. Methods: A retrospective study design was used. Nineteen children were included in the study, including seven girls, aged 4–16 years. All patients were examined for strabismus and 12 were scheduled for surgical intervention. All participants had digital fundus photos (DRSplus, Padova, Italy) of both eyes at presentation, and 5 of 12 also had fundus photos following the strabismus operation. Patient files were reviewed for age, demographic data, type of strabismus, clinical symptoms and signs, orthoptic exams, subjective and objective reports of torsion, inferior oblique overaction, and V pattern. Fundus photos were analyzed for torsion by ImageJ software [ImageJ 1.54f, National Institute of Health, USA]. The disc-foveal angle was calculated for ocular torsion. Disc-foveal angle was defined as the angle formed between a line passing through the center of the optic disc to the fovea and another horizontal line passing through the center of the optic disc, using fundus photographs. Results: Of the 19 children, 18 had horizontal strabismus: 9 with exotropia and 9 with esotropia. One child was orthophoric with torsional strabismus. Inferior oblique overaction was detected in all but 3 children, while V pattern was documented in 10. Visual acuity was reduced (under 6/12) in four eyes of four children. None were symptomatic for ocular torsion. Although extorsion was documented clinically in 3 of 19 children, it was measurable on fundus photos in all patients before surgery with a mean of 8.7 ± 8.5 degrees and 8.5 ± 9.7 degrees in the right and left eyes, respectively. The mean extorsion in both eyes was 19.7 ± 10.1 degrees and improved to a mean of 15.3 ± 7.9 degrees in the children who were operated on and had documented postoperative fundus photographs. Conclusions: Extorsion was detected on fundus photos at a significantly higher rate than in clinical examination. Notably, inferior oblique overaction was mainly associated with torsion. This study demonstrated that torsion is underdiagnosed in clinical examinations, as the children are often asymptomatic, but fundus photos which are easily obtained can improve its detection. Full article

Background and objectives: To analyze demographic and clinical features of pattern strabismus patients and assess the relationship among these clinical variables and risk factors. Materials and Methods: Medical records of pattern strabismus patients who had undergone strabismus surgery at our center between 2014 and 2019 were retrospectively reviewed. Data collected included gender, age at onset, age at surgery, refraction, Cobb angle, pre- and post-operative deviations in the primary position, up- and downgaze, angle of ocular torsion, type/amount of pattern, grade of oblique muscle function and presence/grade of binocular function. To verify the clinical significance of the Cobb angle, 666 patients who had undergone surgery within one week after ocular trauma between 2015 and 2021 were enrolled as controls. Results: Of the 8738 patients with horizontal strabismus, 905 (507 males and 398 females) had pattern strabismus, accounting for 10.36%. Among these 905 patients, 313 showed an A-pattern and 592 showed a V-pattern. The predominant subtype was V-exotropia, followed by A-exotropia, V-esotropia and A-esotropia. Over half of these patients (54.6%) manifested an A- or V-pattern in childhood. The overall mean ± SD Cobb angle was 5.03 ± 4.06° and the prevalence of thoracic scoliosis was 12.4%, both of which were higher than that observed in normal controls (4.26 ± 3.36° and 7.8%). Within A-pattern patients, 80.2% had SOOA and 81.5% an intorsion, while in V-pattern patients, 81.5% had IOOA and 73.4% an extorsion. Patients with binocular function showed decreases in all of these percent values. Only 126 (13.9%) had binocular function, while 11.8% of A-pattern and 15.1% of V-pattern patients still maintained binocular function. Pre-operative horizontal deviation was negatively correlated with binocular function (r = −0.223, p < 0.0001), while the grade of oblique muscle overaction was positively correlated with the amount of pattern (r = 0.768, p < 0.0001) and ocular torsion (r = 0.794, p < 0.0001). There were no significant correlations between the Cobb angle and any of the other clinical variables. There were 724 patients (80.0%) who had received an oblique muscle procedure and 181 (20.0%) who received horizontal rectus muscle surgery. The most commonly used procedure consisted of horizontal rectus surgery plus inferior oblique myectomy (n = 293, 32.4%), followed by isolated horizontal rectus surgery (n = 122, 13.4%). Reductions of pattern were 14.67 ± 6.93 PD in response to horizontal rectus surgery and 18.26 ± 7.49 PD following oblique muscle surgery. Post-operative deviations were less in V- versus A-pattern strabismus. Post-operative binocular function was obtained in 276 of these patients (30.5%), which represented a 16.6% increase over that of pre-operative levels. The number of patients with binocular function in V-pattern strabismus was greater than that of A-pattern strabismus (p = 0.048). Conclusions: Of patients receiving horizontal strabismus surgery, 10.36% showed pattern strabismus. In these patients, 54.6% manifested an A- or V-pattern in childhood, and V-exotropia was the most frequent subtype. Pattern strabismus patients showed a high risk for developing scoliosis. Cyclovertical muscle surgery was performed in 724 of these patients (80.0%), and horizontal rectus surgery was effective in correcting relatively small levels of patterns. Binocular function represented an important factor as being involved with affecting the occurrence and development of pattern strabismus. Full article

Background: To establish in patients with peripheral vestibular disorders relations between skull vibration-induced nystagmus (SVIN) different components (horizontal, vertical, torsional) and the results of different structurally related vestibular tests. Methods: SVIN test, canal vestibular test (CVT: caloric test + video head impulse test: VHIT), otolithic vestibular test (OVT: ocular vestibular evoked myogenic potential oVEMP + cervical vestibular evoked myogenic potential cVEMP) performed on the same day in 52 patients with peripheral vestibular diseases (age < 65 years), and 11 control patients were analyzed. Mixed effects logistic regression analysis was performed to assert whether the presence of nystagmus in SVIN (3D analysis) have an association with the presence of peripheral vestibular dysfunction measured by vestibular explorations (CVT or OVT). Results: We obtained different groups: Group-Co (control group), Group-VNT (dizzy patients with no vestibular tests alterations), Group-O (OVT alterations only), Group-C (CVT alterations only), Group-M (mixed alterations). SVIN-SPV horizontal component was significantly higher in Group-M than in the other groups (p = 0.005) and correlated with alterations of lateral-VHIT (p < 0.001), caloric test (p = 0.002) and oVEMP (p = 0.006). SVIN-SPV vertical component was correlated with the anterior-VHIT and oVEMP alterations (p = 0.007; p = 0.017, respectively). SVIN-SPV torsional component was correlated with the anterior-VHIT positivity (p = 0.017). SVIN was the only positive test for 10% of patients (83% of Group-VNT). Conclusion: SVIN-SPV analysis in dizzy patients shows significant correlation to both CVT and OVT. SVIN horizontal component is mainly relevant to both vestibular tests exploring lateral canal and utricle responses. SVIN-SPV is significantly higher in patients with combined canal and otolith lesions. In some patients with dizziness, SVIN may be the only positive test. Full article

Background: The aim was to investigate the effect of inferior oblique (IO) operation (IO myectomy or graded recession and anteriorization) for unilateral and bilateral superior oblique muscle palsy (SOP); Methods: A total of 167 eyes undergoing IO surgery by a single surgeon between 2008 and 2015 were retrospectively reviewed. The method for treating symmetric bilateral SOP was bilateral IO myectomy (n = 102) and the method for treating unilateral SOP or non-symmetric bilateral SOP was IO-graded recession and anteriorization (n = 65). Associated clinical results and other factors were analyzed; Results: Head tilt, vertical deviation, IO overaction, SO underaction degree and ocular torsion angle were all clearly changed, but there was no statistically significance between these two procedures. Mean preoperative torsional angle was 15.3 ± 6.4 degree, which decreased to 5.3 ± 2.7 degree after surgery. Preoperative torsional angle, IOOA and SOUA degree were all significantly affected in postoperative torsional angle (p = 0.025, 0.003 and 0.038). Horizontal rectus muscle and IO muscle operation did not interfere with each other’s results (p = 0.98); Conclusions: Symmetric bilateral SOP could be treated with bilateral IO myectomy and IO-graded recession and anteriorization should be reserved for unilateral SOP or non-symmetric bilateral SOP. Full article

The current study presents a re-analysis of data from Zink et al. (1998, Electroencephalography and Clinical Neurophysiology, 107), who administered galvanic vestibular stimulation through unipolar direct current. They placed electrodes on each mastoid and applied either right or left anodal stimulation. Ocular torsion and visual tilt were measured under different stimulation intensities. New modelling introduced here demonstrates that directly proportional linear models fit reasonably well with the relationship between vestibular input and visual tilt, but not to that between vestibular input and ocular torsion. Instead, an exponential model characterised by a decreasing slope and an asymptote fitted best. These results demonstrate that in the results presented by Zink et al. (1998), ocular torsion could not completely account for visual tilt. This suggests that vestibular input is processed centrally to stabilise vision when ocular torsion is insufficient. Potential mechanisms and seemingly conflicting literature are discussed. Full article

Acute vertical diplopia requires an immediate neurological evaluation. The preliminary differential diagnosis is based on a few basic questions, which can be answered by simple clinical tests.The neurologist determines whether the lesion affects the optic, ocular motor, or vestibular system, and confirms that the problem is neural. Otherwise the patient is referred to the ophthalmologist. A thorough neurological assessment then allows concluding whether the lesion is within the central nervous system or peripheral. Photographs of the ocular fundus on both sides help to distinguish between trochlear nerve palsy and ocular tilt reaction or skew torsion. For a finer differential diagnosis, focused MR-imaging is always needed. The diagnosis of an optic disorder should be considered if the vertical diplopia is clearly monocular. If vertical diplopia is binocular, the neurologist first searches for typical oculomotor (III) or trochlear nerve (IV) palsies.While III-palsy is mostly due to ischaemia (pupil typically spared) or compression (pupil typically affected) of the nerve, IV-palsy is mostly due to head trauma. III- and IV-palsies that go together with retroorbital pain should lead to a careful evaluation for neoplasm,thrombosis, and inflammation of the cavernous sinus. One can never be absolutely sure whether a typical III- or IV-palsy is due to a problem along the nerve or within the brainstem, except if other signs clearly indicate a lesion within the ipsilateral orbit or cavernous sinus. Thus neuro-imaging should always include MR-imaging of the midbrain to detect lesions in the nuclei and fascicles of the oculomotor and trochlear nerves. If a suspected III-palsy does not include all of the four corresponding extraocular muscles (superior, inferior, and medial recti; inferior oblique), one should also consider myasthenia gravis, which can mimic any neural extraocular muscle palsy. Wernicke’s disease is always a valid differential diagnosis of binocular vertical diplopia, especially in the presence of pathological nystagmus and ataxia. If binocular vertical diplopia is associated with deficits of multiple cranial nerves, one should consider a demyelinating disease such as Miller-Fisher and Guillain-Barré syndrome. Skew deviation is a vertical misalignment of the two eyes resulting from disturbance of supranuclear inputs to the ocular motor neurons of the vertical-torsional eye muscles. If skew deviation goes together with ocular torsion towards the lower eye, so-called skew torsion, an imbalance in the vestibular system, mainly a unilateral lesion of “graviceptive”pathways, which combine otolith and vertical semicircular canal signals, is likely. Skew torsion combined with head roll towards the lower eye forms the triad of ocular tilt reaction (OTR). Consistent with the anatomy of the graviceptive pathways, ipsiversive skew torsion (ipsilateral eye lower, and ipsilateral binocular torsion) and ipsilateral OTR (ipsiversive skew torsion, and ipsilateral head tilt) will occur as a result of unilateral peripheral or pontomedullary lesions below the pontine crossing of the graviceptive pathways. In contrast, a unilateral pontomesencephalic brainstem lesion leads to contraversive skew deviation (contralateral eye lower) and contralateral OTR (contraversive skew deviation, contralateral binocular torsion, and contralateral head tilt). Lesions of cerebellar structures inhibiting the otolith-ocular reflex may also lead to skew torsion. Distinguishing between IV-palsy and OTR is sometimes difficult. In both conditions the head tilts away from the eye showing hyperdeviation. While the upper eye in IV-palsy is extorted, the upper eye in OTR is intorted. Furthermore, the lower eye in OTR is extorted and both eyes may show a torsional spontaneous nystagmus that beats opposite to the static ocular torsion. Full article