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Joseph L Demer

Publications and source records attributed to Joseph L Demer.

At least 37 records · Page 2Linked to original sources
PubMed2005

Extensive persistent pupillary membranes: conservative management.

Extensive persistent pupillary membranes (PPMS) may appear to occlude the pupil so completely as to preclude useful vision. They often motivate aggressive interventions. We present a 6-year-old girl with bilateral extensive densely pigmented pupillary membranes in whom good vision was obtained without pharmacologic, laser, or surgical intervention. There was associated ametropic amblyopia and exotropia in the patient, which were effectively treated with spectacles and occlusion therapy, with the patient responding conventionally. In view of our findings, we recommend a trial of conservative management before surgical intervention even in cases of dense PPMs.

Child↗
PubMed2005

High-resolution magnetic resonance imaging demonstrates varied anatomic abnormalities in Brown syndrome.

INTRODUCTION: Although Brown syndrome classically is considered to be limited to the SO tendon sheath and trochlea, it does not always respond to SO surgery. We investigated mechanisms of Brown syndrome by magnetic resonance imaging (MRI). METHODS: Three patients with congenital and 8 with acquired Brown syndrome were compared with matched normal subjects under a prospective protocol of high-resolution, multipositional orbital MRI using surface coils. Muscle size and contractility were determined using digital image analysis. RESULTS: Five of 8 patients with acquired Brown syndrome had a history of trauma or surgery and demonstrated extensive scarring, avulsion, or fracture of the trochlea. One of the 8 had a cyst in the SO tendon. One congenital and one acquired case demonstrated inferior displacement of the lateral rectus (LR) pulley in adduction, with a normal SO tendon-trochlear complex. Such cases of Brown syndrome responded to surgical stabilization of the LR pulley. Two congenital cases had clinical findings of ipsilateral SO palsy confirmed on MRI by atrophy or absence of the SO belly. In congenital absence of the SO belly, the anterior tendon was present but terminated directly on the trochlea. CONCLUSION: High-resolution MRI demonstrates a variety of abnormalities in patients presenting with Brown syndrome, including atrophy or absence of the SO belly. Management in Brown syndrome should be tailored to the pathophysiology of the individual patient.

Adolescent↗
PubMed2005

Severe strabismus after scleral buckling: multiple mechanisms revealed by high-resolution magnetic resonance imaging.

PURPOSE: Strabismus occurring after scleral buckling for retinal detachment typically is attributed to scarring, but this is not the only mechanism. We investigated use of magnetic resonance imaging (MRI) to identify a spectrum of mechanisms of strabismus occurring after scleral buckling. DESIGN: Prospective, noncomparative, observational case series in an academic referral setting. PARTICIPANTS: Six patients with long-standing, large-angle strabismus after monocular or binocular scleral buckling. Horizontal and vertical preoperative deviations, present from 8 to 120 months, ranged from 25 prism diopters to more than 90 prism diopters. METHODS: Multipositional high-resolution MRI of both orbits was performed using surface coils in multiple, controlled gaze positions. Coronal, sagittal, and axial images were obtained as clinically appropriate. MAIN OUTCOME MEASURES: Different mechanisms of pathologic characteristics of the extraocular muscles (EOMs) in complicated strabismus after scleral buckling. RESULTS: Magnetic resonance imaging readily demonstrated EOM size and contractility, as well as features of scleral buckle hardware such as grooves and junctions and relationships of EOMs to the buckle and sclera. Imaging demonstrated that 5 rectus EOMs were disinserted from the globe at the buckle: 2 superior rectus, 2 medial rectus, and 1 lateral rectus. One patient with suspected inferior rectus muscle disinsertion had restrictive strabismus as a result of interference by a meridional explant and myopic staphyloma. Magnetic resonance imaging demonstrated anterior migration and transection by the silicone element through rectus EOMs in 3 patients. Disinserted EOMs were retrieved successfully by transconjunctival surgery in 4 patients and by orbitotomy in 1 patient, markedly improving alignment even as long as 5 years after EOM disinsertion. CONCLUSIONS: Multipositional high-resolution MRI provides valuable information such as location and contractile potential of disinserted EOMs, as well as mass effect from the scleral buckle. Preoperative orbital MRI may be a useful tool to distinguish multiple mechanisms of persistent severe strabismus after scleral buckling and is helpful in surgical planning.

Adult↗
PubMed2005

Magnetic resonance imaging evidence for widespread orbital dysinnervation in congenital fibrosis of extraocular muscles due to mutations in KIF21A.

PURPOSE: High-resolution orbital magnetic resonance imaging (MRI) was used to investigate the structural basis of ocular motility abnormalities in humans with congenital fibrosis of the extraocular muscles type 1 (CFEOM1) due to missense mutations in the developmental kinesin KIF21A. METHODS: Clinical ophthalmic and motility findings in 19 volunteers from six unrelated CFEOM1 pedigrees harboring four of the six reported KIF21A mutations and 23 normal control subjects were correlated with MRI studies demonstrating extraocular muscle (EOM) size, location, contractility, and innervation. RESULTS: Subjects with CFEOM1 had severe bilateral blepharoptosis, limited supraduction, and variable ophthalmoplegia. In affected subjects, MRI demonstrated atrophy of the levator palpebrae superioris and superior rectus EOMs and small or absent orbital motor nerves. The oculomotor nerve was most severely hypoplastic, but the abducens was also affected. EOMs exhibited variable atrophy and an abnormally bright T1 signal. Subjects with the R954W and R954Q substitutions frequently exhibited A-pattern strabismus, with misinnervation of the lateral rectus muscle by an oculomotor nerve branch. Rectus pulley locations were generally normal. Subjects with CFEOM1 exhibited subclinical but highly significant reduction from normal in mean optic nerve size (P < 0.001). Comparing clinical and MRI phenotypes did not reveal distinguishing features among KIF21A mutations. CONCLUSIONS: Orbital imaging in CFEOM1 due to various amino acid substitutions in the kinesin KIF21A demonstrates consistent abnormalities of motor and sensory innervation in the orbit. These findings suggest that neuronal disease is primary in CFEOM1, with myopathy arising secondary to abnormal innervation and minimal rectus pulley abnormality secondary to reduced EOM forces.

Adolescent↗
PubMed2005

Superior oblique muscle layers in monkeys and humans.

PURPOSE: Rectus and the inferior oblique extraocular muscles (EOMs) consist of orbital layers (OLs), inserting on connective tissues, and global layers (GLs), inserting on the sclera. This study was performed to clarify the anatomic relationships of the corresponding layers of the superior oblique (SO) muscle. METHODS: Two whole human and two monkey orbits were serially sectioned en bloc at 10-mum thickness in the coronal plane and stained for collagen with Masson's trichrome and for elastin with van Gieson's stain. The SO muscles of one human and one monkey were sectioned longitudinally. The structure of the SO muscle was examined by light microscopy, and muscle fibers in the OL and GL of selected sections were counted. RESULTS: The deep SO muscle consisted of a central GL contiguous with the tendon, surrounded coaxially by a peripheral OL inserting on the SO sheath posterior to the trochlea. The maximum number of SO fibers was 14,400 to 19,200 in the human and 7,000 to 7,400 in the monkey. In the monkey, approximately 60% of total fibers were in the GL, and 40% in the OL. The SO sheath was in mechanical continuity with the superior rectus pulley. CONCLUSIONS: The primate SO has a substantial OL configured to contribute to positioning the superior rectus pulley in the coronal plane. Whereas the direction of application of the SO's GL force is determined by the rigid trochlea, the SO's OL influences the direction of application of rectus EOM forces. This insight extends the concept of active control of pulley positions to include a contribution from the SO muscle.

Animals↗
PubMed2005

Kinematics of vertical saccades during the yaw vestibulo-ocular reflex in humans.

PURPOSE: Listing's law (LL) constrains the rotational axes of saccades and pursuit eye movements to Listing's plane (LP). In the velocity domain, LL is ordinarily equivalent to a tilt in the ocular velocity axis equal to half the change in eye position, giving a tilt angle ratio (TAR) of 0.5. This study was undertaken to investigate vertical saccade behavior after the yaw vestibulo-ocular reflex (VOR) had driven eye torsion out of LP, an initial condition causing the position and velocity domain formulations of LL to differ. METHODS: Binocular eye and head motions were recorded with magnetic search coils in eight humans. With the head immobile, LP was determined for each eye, and mean TAR was 0.50 +/- 0.07 (mean +/- SD) for horizontal and 0.45 +/- 0.11 for vertical saccades. The VOR was evoked by transient, whole-body yaw at 2800 deg/s2 peak acceleration, capable of evoking large, uninterrupted VOR slow phases. Before rotation, subjects viewed a target at eye level, 20 degrees up, or 20 degrees down. In two thirds of the trials, the target moved upward or downward at systematically varying times, triggering a vertical saccade during the horizontal VOR slow phase. RESULTS: Because the head rotation axis was generally misaligned with LP, the eye averaged 3.6 degrees out of LP at vertical saccade onset. During the saccade, eye position continued to depart LP by an average 0.8 degrees. The horizontal TAR at saccade onset was 0.29 +/- 0.07. At peak saccade velocity 35 +/- 3 ms later, the vertical TAR was 0.45 +/- 0.07, statistically similar to that of head fixed saccades. Saccades did not return to LP. CONCLUSIONS: Although they did not observe the position domain formulation of LL, vertical saccades, during the VOR, observed the half-angle velocity domain formulation of LL.

Adult↗
PubMed2005

Human angular vestibulo-ocular reflex axis disconjugacy: relationship to magnetic resonance imaging evidence of globe translation.

Magnetic resonance imaging (MRI) demonstrates that the lateral rectus pulley shifts 0.5 mm inferiorly relative to the medial rectus in 20 degrees upgaze, but 0.5 mm superiorly in 20 degrees downgaze, whereas the globe translates 0.7 mm nasally in adduction and 0.2 mm nasally in abduction. If pulleys influence ocular kinematics, these effects would predict disconjugate alterations of the yaw vestibulo-ocular reflex (VOR) rotational axes. Binocular eye and head movements were recorded using three-dimensional search coils in 8 humans (age 24 +/- 2 years, mean +/- SE) undergoing directionally randomized, transient, whole-body yaw (2800 degrees /s2 peak) in darkness while fixating straight ahead, as well as +/- 18 degrees vertically. Eye and head rotational velocity axes were expressed as quaternions in Listing coordinates. In the initial 70 ms, the ocular axis varied with vertical gaze by one-quarter the angle of target elevation, but this effect summed significantly with a disconjugate effect of horizontal duction. In central gaze, the mean adducting eye (AD) rotational axis tilted 3.4 +/- 0.8 degrees forward relative to the head axis, while that of the abducting eye (AB) tilted 0.6 +/- 0.8 degrees backward. In downgaze, the AD rotational axis tilted 8.6 +/- 1.0 degrees forward, and AB 5.7 +/- 1.2 degrees forward. In upgaze, the AD rotational axis tilted backward by 0.1 +/- 0.7 degrees, and AB backward 3.4 +/- 0.9 degrees. We suggest that nasal globe translation relative to the fixed trochlea produces binocular extorsion accounting for yaw VOR axis disconjugacy, and thus a horizontal duction dependence in VOR rotational axis summating with classic dependence of VOR axis on vertical gaze. Confirmation of predicted duction-dependent VOR disconjugacy supports the idea that rectus pulleys influence kinematics for all eye movements.

Fixation, Ocular↗
PubMed2005

Human angular vestibulo-ocular reflex initiation: relationship to Listing's law.

An ideal vestibulo-ocular reflex (VOR) generates ocular rotations compensatory for head motion. During visually guided movements, Listing's law (LL) constrains eye rotation to axes in Listing's plane (LP). Recently, it has been reported that the VOR axis is not collinear with the rotation axis of the head, but is influenced by eye position in the orbit. Elaborate models have been proposed suggesting dynamic neural control of the VOR axis. By examining the variability and time course of changes in VOR axis orientation, we sought to test plausibility of these models. Binocular LPs were defined in eight humans. The VOR was evoked by a highly repeatable, transient, whole-body yaw rotation in darkness at peak acceleration 2800 deg/s2. Immediately prior to rotation, subjects regarded targets at eye level, 20 degrees up, or 20 degrees down. Eye and head positions were expressed in LP coordinates for comparison with LL. Eye position generally followed head position and departed LP when the head axis tilted out of LP. In the velocity domain the VOR axis tilted 28 +/- 9% of the change in vertical eye position, but there was significant intrasubject variation (14% to 41%). This roughly "quarter-angle" behavior began with the earliest detectable VOR. Given the brief latency and marked interindividual variability of the eye position dependence of the VOR rotational axis, and the small deviation of the VOR from LL in the position domain, it is speculated that this behavior is largely due to orbital mechanics interacting with the basic neural commands that initiate the VOR.

Adult↗
PubMed2005

Human surge linear vestibulo-ocular reflex during tertiary gaze viewing.

The otolith-mediated linear vestibulo-ocular reflex (IVOR) was studied in 9 normal humans undergoing transient whole-body surges at 0.5 g peak acceleration while viewing targets eccentrically placed in tertiary positions that combined horizontal and vertical eccentricities at distance of 15, 25, or 50 cm both in darkness and light. Mean velocity gain (+/-SEM) for the horizontal component was 0.61 +/- 0.04 in darkness and increased to 0.72 +/- 0.03 for visible targets (P < 0.05), and for the vertical component was 0.54 +/- 0.02 in darkness, not significantly different from horizontal component gain. For visible targets, vertical component gain significantly increased to 0.63 +/- 0.04 (P < 0.05) with visible targets, but remained significantly less than horizontal component gain.

Eye Movements↗
PubMed2004

Initiation and cancellation of the human heave linear vestibulo-ocular reflex after unilateral vestibular deafferentation.

The effect of unilateral vestibular deafferentation (UVD) on the linear vestibulo-ocular reflex (LVOR) was studied in 11 humans an average of 52 months following surgical UVD. Controls consisted of seven healthy age-matched subjects. The LVOR was evoked by directionally random, transient whole body interaural (heave) translation with a peak acceleration of 0.5 g while subjects viewed earth-fixed (LVOR) and head-fixed (cancellation) targets 15, 25, and 200 cm distant. The magnitude of the LVOR slow phase was inversely proportional to target distance for both subject groups. Neither latency nor the magnitude of the LVOR significantly differed in the ipsi- vs contralesional directions (P>0.1) in UVD. When the target disappeared at heave onset, subjects with UVD had LVOR slow phase displacement 100 ms later that was 5% of ideal at 15 cm, 6% at 25 cm, and 16% at 200 cm. This was significantly less than corresponding control values of 41, 43, and 50%. During cancellation the LVOR magnitude 100 ms from heave onset was reduced at all target distances by an average of 40+/-4%, and the relative reduction did not significantly differ between controls and subjects with UVD (P>0.1). Cancellation latency did not vary significantly among target distances or subject groups. It is concluded that after UVD, the LVOR is bilaterally and symmetrically reduced but remains modulated by viewing distance and cancellation effort.

Adult↗
PubMed2004

Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis.

The mechanisms controlling axon guidance are of fundamental importance in understanding brain development. Growing corticospinal and somatosensory axons cross the midline in the medulla to reach their targets and thus form the basis of contralateral motor control and sensory input. The motor and sensory projections appeared uncrossed in patients with horizontal gaze palsy with progressive scoliosis (HGPPS). In patients affected with HGPPS, we identified mutations in the ROBO3 gene, which shares homology with roundabout genes important in axon guidance in developing Drosophila, zebrafish, and mouse. Like its murine homolog Rig1/Robo3, but unlike other Robo proteins, ROBO3 is required for hindbrain axon midline crossing.

Adult↗
PubMed2004

Medial rectus pulley posterior fixation is as effective as scleral posterior fixation for acquired esotropia with a high AC/A ratio.

PURPOSE: To compare traditional medial rectus (MR) scleral posterior fixation versus MR pulley posterior fixation without scleral sutures for the treatment of acquired esotropia (ET) with a high accommodative convergence over accommodation (AC/A) ratio. DESIGN: Nonrandomized interventional case series. METHODS: Medical records were retrospectively reviewed for twenty-two patients who underwent bilateral MR posterior fixation for acquired ET with a high AC/A ratio, with or without associated MR recessions. The main outcome measure was the reduction in distance-near disparity created by MR scleral posterior fixation compared with MR pulley posterior fixation. RESULTS: Nine patients underwent MR scleral posterior fixation surgery, seven in combination with MR recessions for distance ET. Postoperatively, the distance-near disparity decreased an average of 11.8 prism diopters, stereoacuity improved in six patients, and eight patients no longer needed bifocals. Thirteen patients underwent MR pulley posterior fixation surgery, 10 in combination with MR recessions for distance ET. Postoperatively the distance-near disparity decreased an average of 14.4 prism diopters, stereoacuity improved in eight patients, and 12 patients no longer required bifocals. Statistically, the two procedures were equivalent. One patient in each group was undercorrected at near only, with the residual near ET controlled with bifocals. One patient who underwent MR pulley posterior fixation combined with large MR recessions was overcorrected at distance only. CONCLUSION: Traditional MR scleral posterior fixation and MR pulley posterior fixation are equally effective in treating acquired ET with a high AC/A ratio.

Accommodation, Ocular↗
PubMed2004

Strabismic complications following endoscopic sinus surgery: diagnosis and surgical management.

INTRODUCTION: Endoscopic surgical techniques improve the surgeon's view of sinus structures but are subject to extraocular muscle complications that cause permanent diplopia. METHODS: A series of 15 patients with strabismus following endoscopic sinus surgery was reviewed retrospectively to characterize the type of muscle injury and report the results of surgical correction. RESULTS: A variety of insults to the medial rectus (MR) muscle occurred, ranging from contusion, hematoma, oculomotor nerve damage with paralysis, muscle transection, and muscle destruction. Inferior rectus and superior oblique muscle trauma was observed. High-resolution computed tomography and magnetic resonance imaging scans proved essential in determining the extent and nature of muscle injury. Surgical approaches included anterior orbitotomy with muscle recovery and transposition procedures. CONCLUSIONS: Several extraocular muscles may be traumatized. Timing and type of surgical treatment depend on severity, type of injury, and number of muscles involved. If the remaining posterior segment of the MR muscle is longer than 20 mm and is contractile, muscle recovery via anterior orbital approach is suggested. If injury is more severe, muscle transposition procedures may be helpful. In cases where there is coexistent medial and inferior rectus injury, transposition procedures may not be possible. Inactivation of the antagonist and use of an orbital periosteal flap as a globe tether to center it may be options.

Endoscopy↗
PubMed2004

Orbital imaging demonstrates occult blow out fracture in complex strabismus.

BACKGROUND: While strabismologists are familiar with diagnostic evaluation of suspected blow out fractures, unsuspected blow out fractures may further complicate difficult cases of strabismus not clinically supposed to be related to orbital trauma. METHODS: According to a prospective protocol, we studied five adults presenting with diplopia, and one with convergence-related asthenopia. No patient recalled or had any clinical suspicion of orbital fracture at initial evaluation. Surface coil magnetic resonance imaging of the orbits was performed at 312 microm resolution, slice thickness 2 mm. Quasicoronal images in central gaze were supplemented with eccentric gaze positions, and sagittal and axial images as indicated. RESULTS: Five patients had incomitant hypertropia, and one had abducens paralysis. Magnetic resonance imaging disclosed previously unsuspected blow out fractures in all six patients. Three patients had medial wall fracture, one bilaterally. Two patients had inferior wall fractures, and one inferomedial. Although only one patient had an extraocular muscle displaced into a sinus, all had evidence of orbital connective tissue distortion in the region of the rectus extraocular muscle pulleys influencing muscle paths. These effects altered the presentations of more familiar pathologies such as superior oblique palsy. After learning of the MRI findings, most patients then recalled orbital trauma from as early as childhood. CONCLUSION: Unsuspected blow out fractures occur and may confound the usual findings in complex strabismus. High-resolution orbital imaging can detect blow out fractures and clarify the pathophysiology, enabling appropriate surgical management.

Adult↗
PubMed2004

Inferior rectus pulley hindrance: a mechanism of restrictive hypertropia following lower lid surgery.

PURPOSE: This article describes a new mechanism of restrictive strabismus associated with inferior rectus (IR) pulley hindrance complicating lower eyelid surgery. METHODS: We studied five patients who developed hypertropia in infraduction after bilateral lower eyelid surgery. Complete ophthalmologic examination and multipositional, high-resolution orbital imaging by computed X-ray tomography (CT), or magnetic resonance imaging (MRI) was performed. Comparison was made with MRI in normal volunteers. RESULTS: There was restriction to passive infraduction of the involved eyes. Sagittal MRI images showed hindrance to normal posterior shift of the IR pulley from central to infraducted gaze. Intraoperative findings of contracture of the inferior fornix and dense fibrous scar tissue from the inferior orbital rim to the IR pulley complex correlated with restricted infraduction and imaging findings. Release of the scar tissues around the IR pulley improved infraduction, reducing or eliminating diplopia. CONCLUSION: Scar formation hindering anteroposterior travel of the IR pulley system is a novel mechanism of restrictive hypertropia in infraduction following lower eyelid surgery. This restrictive strabismus, the iatrogenic equivalent of retroequatorial myopexy, is distinct from paralytic strabismus and must be managed differently. Avoidance and treatment of this complication of lower eyelid surgery requires knowledge of anatomical relationship between the IR pulley and lower eyelid.

Adult↗
PubMed2004

Medial rectus pulley posterior fixation: a novel technique to augment recession.

PURPOSE: Medial rectus (MR) pulley posterior fixation, a technique of suturing the pulley to its muscle without scleral sutures, may be as effective as traditional scleral posterior fixation in primary treatment of acquired esotropia (ET) with a high AC/A ratio. This study examines the effectiveness of MR pulley posterior fixation for other variants of ET. METHODS: We retrospectively analyzed the pre- and postoperative alignment of 16 patients: 9 previously operated patients with excess near ET, 4 patients with sensory ET with excess near ET, and 3 patients with large-angle infantile ET. Surgeries involved extraocular muscle recessions and resections in standard doses combined with MR pulley posterior fixation. RESULTS: All 9 reoperated patients were between 0 and 10 prism diopters of distance ET postoperatively. The excess near ET decreased from an average of 12.1 prism diopters preoperatively (range 6-20) to 1.3 prism diopters postoperatively (range, 0-4). Two of the 4 patients with sensory ET were overcorrected at distance (exotropia of 10 and 15 prism diopters, respectively). The excess near ET of these 4 patients decreased from an average of 13.5 prism diopters preoperatively (range, 10-20) to 2.5 prism diopters postoperatively (range, 0-8). In patients with large-angle infantile ET, the addition of pulley posterior fixation resulted in a greater effect than would be predicted for standard MR recessions, particularly at near. Pooling data for all groups, pulley posterior fixation was associated with a highly significant reduction of excess near esotropia postoperatively (P < 0.00001). DISCUSSION: MR pulley posterior fixation augments MR recession with relatively greater effect at near. Surgical dosage for unilateral recessions and resections combined with MR pulley posterior fixation should be reduced in patients with poor potential for postoperative fusion.

Adolescent↗
PubMed2004

Demonstration of systematic variation in human intraorbital optic nerve size by quantitative magnetic resonance imaging and histology.

PURPOSE: To use magnetic resonance imaging (MRI) to measure the diameter along the course of the intraorbital optic nerve in living subjects and cadaveric specimens, and to validate measurements histologically in the same specimens. METHODS: Measurements of the intraorbital optic nerve were made in 23 living human subjects and in three formalin-fixed orbits using high-resolution, surface coil MRI in the coronal plane. Fixed orbits were then serially sectioned in the same plane, and stained by Masson's trichrome for digital morphometry of nerve diameter and densitometry of connective tissue constituents. RESULTS: In cadaveric specimens, MRI and histologic measurements of optic nerve dimensions were in close quantitative agreement, showing significant decrease in the average optic nerve diameter along its retrobulbar course. This finding was confirmed by MRI in living subjects, with average optic nerve diameter declining from 3.99 +/- 0.04 mm (SEM) just posterior to the globe, to 3.50 +/- 0.04 mm at 10 mm further to the posterior (P < 0.0001). Color densitometry demonstrated a consistent cross-sectional area of nervous tissue, but decreasing amounts of collagen posteriorly. CONCLUSIONS: There is a significant decrease in normal optic nerve diameter along its length in normal subjects, reflecting reduction in connective tissue. High-resolution MRI is a valid and sensitive method of detecting subtle changes in retrobulbar optic nerve size and can be useful in the investigation of structural optic nerve lesions. Optic nerve diameters must be measured, however, at similar distances posterior to the globe to allow meaningful comparisons.

Adult↗