Ocular Rotation Research Articles

Uniocular and binocular fields of rotation measures: Octopus versus Goldmann

To compare the range of ocular rotations measured by Octopus versus Goldmann perimetry. Forty subjects (20 controls and 20 patients with impaired ocular movements) were prospectively recruited, age range 21-83years. Range of uniocular rotations was measured in six vectors corresponding to extraocular muscle actions: 0°, 67°, 141°, 180°, 216°, 293°. Fields of binocular single vision were assessed at 30° intervals. Vector measurements were utilised to calculate an area score for the field of uniocular rotations or binocular field of single vision. Two test speeds were used for Octopus testing: 3°/ and 10°/second. Test duration was two thirds quicker for Octopus 10°/second than for 3°/second stimulus speed, and slightly quicker for Goldmann. Mean area for control subjects for uniocular field was 7910.45 degrees(2) for Goldmann, 7032.14 for Octopus 3°/second and 7840.66 for Octopus 10°/second. Mean area for patient subjects of right uniocular field was 8567.21 degrees(2) for Goldmann, 5906.72 for Octopus 3°/second and 8806.44 for Octopus 10°/second. Mean area for left uniocular field was 8137.49 degrees(2) for Goldmann, 8127.9 for Octopus 3°/second and 8950.54 for Octopus 10°/second. Range of measured rotation was significantly larger for Octopus 10°/second speed. Our results suggest that the Octopus perimeter is an acceptable alternative method of assessment for uniocular ductions and binocular field of single vision. Speed of stimulus significantly alters test duration for Octopus perimetry. Comparisons of results from both perimeters show that quantitative measurements differ, although qualitatively the results are similar. Differences per mean vectors were less than 5° (within clinically accepted variances) for both controls and patients when comparing Goldmann to Octopus 10°/second speed. However, differences were almost 10° for the patient group when comparing Goldmann to Octopus 3°/second speed. Thus, speed of stimulus must be considered if wishing to use these perimeters interchangeably.

Situational Restriction: Using Your Physical Exam to Differentiate Pulley Abnormalities from Other Vertical Deviations Secondary to Restrictive Conditions

The description of the orbital pulley system has changed the way we understand eye movements and ocular motility disorders. The presence of abnormalities in the orbital pulley system can complicate the assessment of vertical restrictive conditions. The standard tests for restriction are reviewed. These include version and duction testing, assessing saccades, differential intraocular pressure measurements, forced duction testing, and forced generation testing. We introduce the concept of situational restriction and how to look for it during your physical exam. Situational restriction is a limitation of ocular rotation that is dependent on the path that is taken to try to arrive at a tertiary position of ocular rotation. Specifically, it shows noncommutative movement that breaks Listing's Law. The presence of situational restriction denotes that a pulley abnormality is present.

Paraxial Ocular Rotation with Astigmatic Lenses

To obtain analytical formulas for calculating the ocular rotation and the prismatic effect with a general lens, centered or decentered, with particular reference to thick spherotoric spectacle lenses. Linear theory is used, using the symplectic properties of optical matrices, to derive the desired formulas. By applying the general formulas to particular cases, the corresponding formulas are obtained, sometimes recovering formulas already known. Two examples serve to illustrate the use of the formulas obtained and to compare the results they provide with the ones obtained by exact ray tracing. The linear formulas derived allow to find, in a rather easy way, quite accurate values of the ocular rotation and the prismatic effect in the paraxial region.

Binocular Visual Function in Patients With Boston Type I Keratoprostheses

To report the postoperative binocular function of patients with Boston type I keratoprostheses implantation for unilateral visual impairment. Seventeen patients who underwent implantation of a Boston type I keratoprosthesis and had a best-corrected visual acuity better than 20/50 in the contralateral eye before surgery were evaluated. All subjects prospectively underwent sensory testing of binocular function including Bagolini lenses, Worth-4-dot test, stereoacuity at distance and near, and double Maddox rods. In addition, an assessment of ocular rotations and alignment was performed on each subject. Twenty patients with best-corrected visual acuity better than 20/50 in the contralateral eye at the time of keratoprothesis surgery were identified. Seventeen of the 20 patients underwent binocular visual testing, with 16 of 17 (94%) demonstrating binocular function. Second-degree fusion at near was demonstrated via the Worth-4-dot test in 13 of 17 (76%) patients. Third-degree fusion at near was demonstrated in 7 of 17 (41%) patients. Patients with better postoperative sensory binocular function tended to be of younger age (P = 0.05) and have better postoperative visual acuity (P = 0.006). Five patients were found to have some degree of ocular misalignment. Overall, patients with strabismus had worse binocularity (P = 0.04). Implantation of the Boston type I keratoprosthesis in patients with good preoperative visual acuity in the fellow eye is associated with useful binocular function in greater than 90% of patients.

Visuomotor Velocity Transformations for Smooth Pursuit Eye Movements

Smooth pursuit eye movements are driven by retinal motion signals. These retinal motion signals are converted into motor commands that obey Listing's law (i.e., no accumulation of ocular torsion). The fact that smooth pursuit follows Listing's law is often taken as evidence that no explicit reference frame transformation between the retinal velocity input and the head-centered motor command is required. Such eye-position-dependent reference frame transformations between eye- and head-centered coordinates have been well-described for saccades to static targets. Here we suggest that such an eye (and head)-position-dependent reference frame transformation is also required for target motion (i.e., velocity) driving smooth pursuit eye movements. Therefore we tested smooth pursuit initiation under different three-dimensional eye positions and compared human performance to model simulations. We specifically tested if the ocular rotation axis changed with vertical eye position, if the misalignment of the spatial and retinal axes during oblique fixations was taken into account, and if ocular torsion (due to head roll) was compensated for. If no eye-position-dependent velocity transformation was used, the pursuit initiation should follow the retinal direction, independently of eye position; in contrast, a correct visuomotor velocity transformation would result in spatially correct pursuit initiation. Overall subjects accounted for all three components of the visuomotor velocity transformation, but we did observe differences in the compensatory gains between individual subjects. We concluded that the brain does perform a visuomotor velocity transformation but that this transformation was prone to noise and inaccuracies of the internal model.

Long-term results of the surgical management of intermittent exotropia

To examine long-term surgical success rates (>10 years) for patients with intermittent exotropia and the risk factors for failure of surgery in these patients. An attempt was made to contact all patients who underwent surgical treatment for intermittent exotropia between the years of 1970 to 1998 with a minimum postoperative follow-up of 10 years. Each patient underwent a detailed sensory and motor examination, including measurements of near and distance stereoacuity, cover testing, and ocular rotations. Patients were classified as achieving an excellent, fair, or poor outcome on the basis of motor and sensory outcomes. Risk factor analysis was performed to evaluate associations with a poor outcome and reoperations. Of 197 patients identified, 50 were reevaluated. When combined motor/sensory criteria for surgical success were used, we found that 38% of patients achieved an excellent outcome, whereas 34% and 28% achieved a fair or poor outcome, respectively. When only the motor criteria were used, we found that 64% had an excellent outcome, whereas the remaining patients achieved either a fair (18%) or a poor (18%) outcome. During the follow-up period, 60% of patients required at least one reoperation. Multivariate risk factor analysis determined that anisometropia (p = 0.03) was associated with a poor outcome, whereas postoperative undercorrection (p = 0.04) and lateral incomitance (p = 0.06) were associated with reoperations. Long-term surgical results in intermittent exotropia are less encouraging when sensory status is added to the evaluation. Patients with anisometropia, lateral incomitance, and immediate postoperative undercorrection are at increased risk for poor outcomes and to require reoperations.

Peaks and Troughs of Three-Dimensional Vestibulo-ocular Reflex in Humans

The three-dimensional vestibulo-ocular reflex (3D VOR) ideally generates compensatory ocular rotations not only with a magnitude equal and opposite to the head rotation but also about an axis that is collinear with the head rotation axis. Vestibulo-ocular responses only partially fulfill this ideal behavior. Because animal studies have shown that vestibular stimulation about particular axes may lead to suboptimal compensatory responses, we investigated in healthy subjects the peaks and troughs in 3D VOR stabilization in terms of gain and alignment of the 3D vestibulo-ocular response. Six healthy upright sitting subjects underwent whole body small amplitude sinusoidal and constant acceleration transients delivered by a six-degree-of-freedom motion platform. Subjects were oscillated about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5° in azimuth. Transients were delivered in yaw, roll, and pitch and in the vertical canal planes. Eye movements were recorded in with 3D search coils. Eye coil signals were converted to rotation vectors, from which we calculated gain and misalignment. During horizontal axis stimulation, systematic deviations were found. In the light, misalignment of the 3D VOR had a maximum misalignment at about 45°. These deviations in misalignment can be explained by vector summation of the eye rotation components with a low gain for torsion and high gain for vertical. In the dark and in response to transients, gain of all components had lower values. Misalignment in darkness and for transients had different peaks and troughs than in the light: its minimum was during pitch axis stimulation and its maximum during roll axis stimulation. We show that the relatively large misalignment for roll in darkness is due to a horizontal eye movement component that is only present in darkness. In combination with the relatively low torsion gain, this horizontal component has a relative large effect on the alignment of the eye rotation axis with respect to the head rotation axis.Electronic supplementary materialThe online version of this article (doi:10.1007/s10162-010-0210-y) contains supplementary material, which is available to authorized users.

Correlazione tra i sistemi stomatognatico e oculomotore nel determinismo della postura

Objectives To establish if oculomotor apparatus, stomatognathic apparatus and postural system are someway related. Materials and methods Ocular deficit, postural stabilization, head inclination and rotation, shoulder position and dental class were assessed by convergence test, cover test, postural and stomatognathic examination in a sample of 22 patients with ocular disease (convergence deficit, strabismus and heterophoria) aged from 10 to 18 years. Results In patients with convergence's deficit, body axis deviated to left (65%) and head inclination to right (65%), right shoulder was higher (68%) and I dental class was observed (49%); in patients with strabismus, body axis deviated to left (54%) and head inclination to left (53%), right shoulder was higher (61%) and II dental class was observed (33%); patients with heterophoria showed head inclination to left (98%), body axis and higher shoulder deviated to left (78%) and I-II dental class (33%). Conclusions This study suggests that head inclination on the left side in patients with convergence's deficit or strabismus and head inclination on the right side in patients with heterophoria compensate ocular deficit.

Estrabismos: da teoria à prática, dos conceitos às suas operacionalizações

Some particular points concerning the study of strabismus are analyzed, specially, the difficulties for definitions and the different ways it can be conceived, besides the relativity of binocular positions interpretation, and the necessary referential elements for circumscribing such questions. Then, the concept of primary position of gaze is discussed as well as the conditions for its operational attainment, leading to the conclusion that it is materially impossible to achieve this 'zero' point, from which all other measurements of strabismus or ocular movements should be done. In sequence, the construction of multiple referential systems applying the quantification of strabismus are examined. The lack of consensual agreement about which should be used as the standard system causes elementary practical implications, as the lack of agreement about how to superimpose orthogonal prisms for the measurement of associated horizontal and vertical deviations. The functional asymmetry of ocular rotations and its exceptions are commented. The accuracy that the measurements of strabismus can be performed is analyzed, leading to the conclusion that fractional figures using the commonest angular unities are improper. At last, some technical problems related to such evaluations are also commented, as operational difficulties related to prism-diopter unity, concerning the use of prisms, and prismatic effects due to the use of conventional optical glasses.

A comparative review of methods to record ocular rotations

Aim: To review the methods reported for recording ocular rotations. Methods: A literature-based review from 1899 to 2008 was carried out to enable a comparative discussion on the methods available to record ocular rotations. Results: The recording of ocular rotations has changed and progressed over the years. Different methods are available that are essentially either kinetic or static. The important factors in evaluating the efficacy of methods for recording ocular rotations are: minimising patient discomfort; maintaining accuracy and minimising variability from head and chin movement; the speed and simplicity of the test, particularly for elderly patients; good repeatability and level of inter- and intra-observer reliability. Conclusion: No one method has been advocated in the literature as the gold standard. However, clinically the Goldmann perimeter for kinetic recording and the Lees screen for static recording are popular.

Eye rotation does not contribute to shifts in subjective straight ahead: Implications for prism adaptation and neglect

Prism adaptation has received much attention in recent years as a potential method for the rehabilitation of visual neglect. Recent theories as to the underlying mechanisms include oculomotor resetting and pathological realignment of subjective straight ahead (SSA). Typical prism adaptation procedures involve both ocular rotation and manual correction making the precise mechanisms and contribution of these to the amelioration of neglect difficult to determine. This experiment separated the contributions of ocular rotation and manual error reduction to SSA realignment in normal participants by shifting the eye alone, the hand alone or both together. Rotating the eye alone did not contribute to SSA realignment whereas shifting the hand did.

Binocular Vertical Rectus Muscle Recession For Comitant Vertical Strabismus

Binocular vertical rectus muscle recession has not been formally evaluated in the correction of comitant vertical strabismus. Eight patients with stable comitant vertical strabismus for at least 6 months were included. All underwent recession of the superior rectus muscle of the hypertropic eye combined with an equal or nearly equal recession of the inferior rectus muscle in the hypotropic eye. On the day before surgery, on one of the first three postoperative days, and at one year postoperatively, ocular alignment in vertical and horizontal gaze directions were measured with simultaneous and alternate cover test at a viewing distance of 5 meters, and with the two dimensional Hess screen test. The field of single binocular vision was determined with a Goldmann perimeter. The Lang stereopsis chart was presented at the last follow-up visit. All patients were orthotropic at the last postoperative follow-up visit. In primary gaze, the degree of vertical and horizontal phoria diminished significantly. Normal alignment was achieved in nearly all gaze directions and stereopsis was reestablished. The field of single binocular vision enlarged after the surgery. Binocular vertical rectus muscle recession is an effective surgical approach for patients with comitant vertical ocular misalignment.

Modulation of Saccade Curvature by Ocular Counterroll

On close inspection, it can be seen that most saccadic trajectories are not straight but curve slightly; in other words, they are not single-axis ocular rotations. The authors asked whether saccade curvatures are systematically influenced by static ocular counterroll (OCR). OCR was elicited by static whole-body roll position. Eight healthy human subjects performed horizontal and vertical saccades (10 degrees amplitude; 0 degrees and 10 degrees eccentricity; head-fixed coordinate system) in upright and ear-down whole-body roll positions (45 degrees right, 45 degrees left). Three-dimensional eye movements were recorded with modified dual-search coils at 1000 Hz. Saccade curvature was systematically modulated by OCR depending on saccade direction. In the horizontal-vertical plane, primarily vertical saccades were modulated with downward saccades curving toward the upper ear and upward saccades curving toward the lower ear. Modulation of saccade curvature in the torsional direction correlated significantly with OCR only in abducting saccades. No universal mechanism, such as visual-motor coordinate transformation or kinematic characteristics of the saccadic burst generator, alone could explain the complex modulation pattern of saccade curvature. OCR-induced changes of the ocular motor plant, including transient force imbalances between agonist eye muscles (vertical rectus and oblique muscles) and shifting eye muscle pulleys, are suitable to explain the found direction-dependent modulation pattern.

Surgical Treatment of Strabismus Secondary to Glaucoma Drainage Device

To describe surgical strategies in a series of patients with diplopia following implantation of a glaucoma drainage device. Retrospective review of 9 consecutive patients who underwent strabismus surgery because of strabismus and diplopia after implantation of a glaucoma drainage device. Seven patients with marked limitation to ocular rotations and incomitant strabismus underwent surgery on the eye with the implant. Two patients with mild limitation to ocular rotations of the involved eye underwent surgery on the contralateral eye. All patients had a large fibrous capsule surrounding the implant plate, adjacent muscles, and sclera. Intraocular pressure was not elevated postoperatively. Postoperative diplopia in the primary position was eliminated in 5 patients and markedly improved in 3 patients. Strabismus following implantation of a glaucoma drainage device is an uncommon but serious complication. Restoration of ocular alignment is a complex undertaking requiring strabismus and glaucoma surgical expertise. Multiple surgical complications may occur. Surgical intervention may require complete removal of the fibrous capsule surrounding the implant and involved adjacent structures. Size reduction of the implant plate is helpful and did not interfere with postoperative intraocular pressure control in this study. Surgery on the contralateral eye is an option in patients with mild restriction.

Peripheral retinal shape measurements, using the IOLMaster, in myopia and hyperopia

Purpose: When measuring peripheral retinal shape using the IOLMaster, measurements have been taken with the instrument in a fixed position and the subjects rotating their eye to measure peripherally. However, eye rotation could affect the peripheral ocular shape measures. The aim of this experiment is to determine the effect of eye rotation upon the measurement of peripheral retinal shape in myopic and hyperopic subjects using the IOLMaster.Methods: 20 subjects participated with informed consent in the experiment [10 myopes (MYO) and 10 hyperopes (HYP)]. All subjects were visually normal with visual acuity of 0.0 logMAR or better. The mean age of the subjects was 21.4 ± 2.2 years, and all were students in the University. Cycloplegia and mydriasis were induced using 1.0% cyclopentolate and the measurements were taken 30 min after instillation of the eyedrops. Peripheral retinal dimensions were measured with the IOLMaster (Carl Zeiss Ltd., Welwyn Garden City, UK) which measures axial length using partial coherence interferometry. 5 measures of axial length were taken at 10 degree intervals from 0–40 degree nasally and temporally using two different experimental paradigms. Experiment 1: Subjects rotated their eye to view an LED target array, attached to the front of the instrument. Experiment 2: Subjects maintained fixation upon a stationary target in the primary position while the IOL‐Master was rotated about the centre of rotation of the eye. The data was fitted with second order polynomials with separate curves being fitted to the temporal and nasal profiles to take into account any retinal asymmetry.Results: A significant difference (p < 0.01) was found in the mean second order coefficients for the temporal and nasal retinal profiles in the MYO subjects, with the temporal retina having the lower coefficient. There was no significant difference between temporal and nasal second order coefficients in the HYP subjects. Eye rotation produced a significant shift in the second order coefficients for both temporal (p < 0.01) and nasal (p < 0.01) retinal profiles in the MYO group, with the coefficients becoming smaller with ocular rotation. No significant effect of eye rotation was found in the HYP group.Conclusions: Asymmetry between the temporal and nasal retinal profiles is more pronounced in the myopic eye. Ocular rotation has a substantial and measurable effect on the shape of the myopic eye, but no measurable effect is found in the hyperopic eye. These results are indicative of substantial structural differences between the eyes of subjects with myopia and hyperopia. When measuring peripheral retinal shape these factors should be taken into account.

General Principles in the Surgical Treatment of Paralytic Strabismus

The surgical approach necessary to achieve the largest field of usable single binocular vision in patients with paralytic strabismus is one that has a greater effect in some directions of gaze than in others. Developing the appropriate “incomitant” strabismus surgery can be achieved by improving the ocular rotation of the involved eye(s), creating a matching rotation defect in the “normal” eye, and anticipating that surgery may create a new/different deviation (not present before the surgery) that can be used to surgeons' advantage. The severity of the limitation in ocular rotation will determine the amount and type of strengthening or weakening that will be necessary to the paralytic muscle and its yoke muscle.

First observations of young of the year and juvenile great white sharks (Carcharodon carcharias) scavenging from a whale carcass

Observations of great white sharks (Carcharodon carcharias) scavenging from cetacean carcasses are rare and have only been reported in the scientific literature for large (>3.5 m total length (TL)) individuals. Between 13 October and 25 November 2006, young of the year and juvenile great white sharks were observed scavenging from the carcass of a humpback whale (Megaptera novaeangliae) in Algoa Bay, South Africa. Although more than one shark scavenged from the carcass, simultaneous feeding was not observed. The sharks showed a clear preference for soft tissue at sites along the mouth of the carcass. Protective ocular rotation was rarely observed and none of the sharks exhibited palatoquadrate protrusion while feeding. These observations provide a new insight into the foraging behaviour of young of the year and juvenile great white sharks. The prevalence of small great white sharks (1.5 m TL) and the absence of any individuals greater than 3.65 m TL suggest that Algoa Bay may function as a nursery area for great white sharks in South Africa. This information is crucial not only to improve our understanding of great white shark biology, but also for their long-term management and conservation in South Africa.

Vestibulo-ocular responses to vertical translation in normal human subjects

Prior studies of the human translational vestibulo-ocular reflex (tVOR) report that eye rotations amount to less than 60% of those required to keep the eyes pointed at a stationary visual target, unlike the angular VOR (aVOR) which is optimized to maintain stable gaze. Our first goal was to determine if the performance of the tVOR improves when head translations are combined with head rotations in ambient lighting. A second goal was to measure tVOR during vertical head translations (bob), which has not received systematic study. We measured tVOR alone and in combination with the aVOR in 20 normal human subjects, aged 25-72 years, as they sat on a moving platform that bobbed at 2.0 Hz while rotating horizontally (yaw) at 1.0 Hz. When subjects viewed a visual target at 2 m, median "compensation gain" (eye rotational velocity/required eye rotational velocity to maintain foveal target fixation) was 0.52 during pure bob and 0.59 during combined bob-yaw; during viewing of a near target at approximately 17 cm, compensation gain was 0.58 for pure bob and 0.60 for combined bob-yaw. Mean phase lag of eye-in-head velocity for the tVOR was approximately 19 degrees with respect to the ideal compensatory response, irrespective of whether translation was accompanied by rotation. Thus, the tVOR changed only slightly during translation-rotation versus pure translation, and our subjects' ocular rotations remained at about 60% of those required to point the eyes at the target. Comparison of response during binocular or monocular viewing, and ambient or reduced illumination, indicated that relative image motion between the target and background was an important determinant of tVOR behavior. We postulate that tVOR evolved not to stabilize the image of the target on the fovea, but rather to minimize retinal image motion between objects lying in different planes, in order to optimize motion parallax information.

A 10-Year Overview of Double Elevator Muscle Weakening Procedures

To report the effect of weakening the superior rectus and inferior oblique (IO) muscles on ocular rotations. Observational case series. We reviewed a 10-year period of medical records of consecutive patients who underwent bilateral 5- to 11-mm (mean, 8.0 mm; SD, 1.1 mm) superior rectus muscle recessions combined with an IO muscle recession, myectomy, or anterior transposition. The effects on ocular rotations and eyelid position were recorded for the 37 patients (69 eyes) who were followed up for at least 6 months postoperatively. Nonparametric 1-way analysis of variance was used to compare results across the 3 procedures. The setting was a subspecialty practice at an academic institution. Supraduction deficiency was significantly associated with transposition of the IO muscle anterior to the inferior rectus muscle insertion compared with the standard IO muscle recession (P = .001), and IO muscle myectomy (P = .009). Y-pattern exotropia occurred more frequently after transposition of the IO muscle anterior to the inferior rectus muscle insertion than other weakening procedures (P<.001). Transposition of the IO muscle anterior to the inferior rectus muscle insertion, combined with ipsilateral superior rectus muscle recession, results in more supraduction deficiency and more frequent Y-pattern exotropia compared with standard IO muscle recession.

Seqüência de Möbius: resultados a longo prazo, da correção cirúrgica do estrabismo

To analyze the long-term results in a consecutive series of Möbius sequence patients, who underwent surgical correction of strabismus. Ten patients with Möbius sequence fulfilled the inclusion criteria of this study. All patients presented esotropia at the preoperative examination, above or equal to 15 prismatic diopters (DP) varying from 15 to 85. All patients presented lateral rectus muscles severe underaction, six presented hipertropia above or equal 10 DP associated with esodeviation, and five presented anisotropia in A or in V. The patients were operated upon protocol, in a consecutive way, in July 2002. Patients were reexamined periodically, and at 2nd postoperative year as for: the visual acuity; deviation measurements; ocular rotations; cosmetic aspect and socialization. The patients presented satisfactory surgical results in eight cases, considering an eso or exodeviation up to 15 DP and a hipertropia lower than 10 DP. Four (40%) patients presented correction of the preoperative anisotropia. Variation of ocular deviation in the primary position (from the 90th day to the 2nd postoperative year was observed) in 9 patients (90%), demonstrating that strabismus surgical stabilization needs time. The surgical results were considered satisfactory, improving patient self-esteem and the parent satisfaction, making the social inclusion easier.