Histopathological changes in extraocular muscles of rabbits following injection of bupivacaine 5mg/Ml versus 7.5mg/Ml.

PURPOSE: To compare the histopathological effects of injecting two concentrations of Bupivacaine (5 mg/ml and 7.5 mg/ml) in the superior rectus muscle of rabbits, and to compare these to conventional extraocular muscle surgery in previous studies. METHODS: Eighteen albino rabbits' eyes were used. The superior rectus muscles were injected with Bupivacaine 5 mg/ml (Group B5, 10 eyes) or 7.5 mg/ml (Group B7, 8 eyes). The rabbits were sacrificed and eyes enucleated 6 weeks later for histopathological evaluation. Results were compared to the average of those obtained, by three previous studies, after conventional superior rectus resection in rabbits. RESULTS: Foreign body reaction was absent in all specimens. Conjunctival and scleral inflammation, perimuscular adhesions, intramuscular fibrosis, conjunctival and scleral oedema and muscle atrophy were higher in group B7, while conjunctival hyperaemia and muscle hypertrophy were higher in group B5 (p > 0.05). On comparison to conventional surgery, conjunctival inflammation and hyperaemia, foreign body reaction, and adhesions were less after bupivacaine injection (p > 0.05 for all except for intensity of conjunctival inflammation in B5 versus conventional surgery). Scleral inflammation was more frequent after bupivacaine injection (p < 0.05). Muscle fibrosis was more frequent in group B7 and conventional surgery than in group B5 (p > 0.05). CONCLUSIONS: Both Bupivacaine concentrations effectively produced the desired muscle hypertrophy and fibrosis, so the lower concentration may be used for muscle strengthening to correct strabismus. Bupivacaine injection, although produced no foreign body reaction, did not significantly lower the development of undesired postoperative adhesions and caused more scleral inflammation.

Brown Syndrome from Local Anesthesia for Inferior Orbital Fat Decompression.

BACKGROUND Vertical diplopia that follows local anesthesia is usually due to inferior rectus muscle fibrosis. Here, we report a rare case of acquired Brown syndrome following local anesthesia. CASE REPORT A 36-year-old woman underwent right inferior orbital fat decompression under local anesthesia. On the first postoperative day, she developed vertical diplopia. She had left hypertropia, which increased on left gaze, with limitation of elevation of the right eye on attempted adduction. Forced duction test of the right eye revealed resistance on elevation in adduction. Magnetic resonance imaging showed signal alteration, thickening, and irregularity involving the right superior oblique tendon and trochlea region. The diagnosis of iatrogenic Brown syndrome was made. Then, a single dose of 10 mg triamcinolone injection was given near the intratrochlear region. On follow-up, complete resolution of diplopia on primary gaze occurred 12 weeks after the incident. CONCLUSIONS The reported case highlights that local anesthesia carries a risk of Brown syndrome. We believe bupivacaine-induced superior oblique hypertrophy is the underlying mechanism. The patient showed excellent outcome after medical management, with no surgical intervention required after 3 months of follow-up.

Acute, severe dystonia after strabismus surgery in a patient on propofol, ondansetron, and bupropion.

Acute, severe dystonia is a frightening and potentially life-threatening surgical complication. We describe the case of a 41-year-old woman who experienced postoperative drug-induced dystonia after elective strabismus surgery. In this case, the medications likely responsible were propofol, ondansetron, and, possibly, bupropion.

Surgical outcomes of strabismus after iatrogenic ophthalmic artery occlusion caused by cosmetic filler injections.

BACKGROUND: To investigate the surgical outcomes of strabismus related to iatrogenic occlusion of the ophthalmic artery and its branches from cosmetic facial filler injection. METHODS: A retrospective study was performed on 6 patients who underwent strabismus surgery among 23 patients who had suffered occlusion of the ophthalmic artery and its branches after cosmetic facial filler injection. Initial, preoperative and final ocular motility examinations, the type of surgery and surgical outcomes were evaluated. RESULTS: At initial presentation, visual acuity was no light perception in 5 patients and hand motion in one patient. Five out of 6 patients showed initial ophthalmoplegia. Among these 5 patients, eye motility fully recovered in 3 patients although sensory strabismus developed during follow-up, while the remaining 2 patients had persistent ocular motility limitations. Strabismus surgery was performed at 2.2 ± 1.5 years after iatrogenic ophthalmic artery occlusion. Preoperatively, 5 of the 6 patients showed exotropia, and one patient had esotropia. Vertical deviation was found in 3 out of 6 patients in addition to the horizontal deviation. Successful outcome was achieved only in the 4 patients without persistent ophthalmoplegia after 1.4 ± 1.0 years from surgery. The other two patients with persistent ocular motility limitations failed to achieve successful alignment after surgery, and one patient eventually underwent evisceration due to phthisis bulbi. CONCLUSIONS: In our study, surgical outcomes of strabismus caused by cosmetic facial filler injection were successful only in patients without persistent ophthalmoplegia at the time of surgery.

Visual and oculomotor outcomes in children with prenatal opioid exposure.

PURPOSE OF REVIEW: To summarize the visual and oculomotor outcomes in children with prenatal opioid exposure and review the effects of opioids on the developing central nervous system. RECENT FINDINGS: Animal models and imaging studies in children suggest that prenatal opioid exposure may affect neuronal survival and result in delayed maturation of white matter tracts and decreased volumes in certain brain areas. Visual evoked potential testing in children demonstrates delayed maturation of the afferent visual system in opioid-exposed groups compared with controls, though 'catch-up' development is seen with longitudinal follow-up. Strabismus and nystagmus are also more common in exposed children, and these findings appear to persist. SUMMARY: As rates of opioid dependence and prenatal opioid exposure continue to increase, it is important to evaluate the short-term and long-term effects of opioids on the developing visual system. An understanding of these risks is important when counseling the parents or guardians of opioid-exposed children, though larger studies with more long-term follow-up will improve our prognostic abilities.

Sensorimotor outcomes in children with prenatal exposure to methadone.

PURPOSE: To report the presentation and characteristics of strabismus in children with prenatal methadone exposure. METHODS: The medical records of children with prenatal methadone exposure were retrospectively reviewed. Those who were evaluated by pediatric ophthalmology were included. Information on the timing and types of prenatal exposure by trimester of pregnancy was then collected from the patients' mothers' charts. The children's perinatal histories and ophthalmologic findings were collected from their pediatric clinic charts and ophthalmology clinic charts, respectively. RESULTS: A total of 210 children with prenatal methadone exposure were identified, of whom 32 (15.2%) underwent eye examinations and 21 (10%) had strabismus. Five patients had esodeviations, with a mean age of onset of 11.6 months; 16 had exodeviations, with a mean age of onset of 6.8 months. Three patients with strabismus were born prematurely, and 2 had intracranial disease. Two patients underwent strabismus surgery. CONCLUSIONS: The incidence of strabismus in patients with prenatal methadone exposure was higher than in the general population (10% vs 3%-4%). Intermittent exotropia was the most common type of strabismus and presented earlier than in the general population, with no association with other systemic disease. Prenatal exposure to methadone was likely confounded by exposure to other substances, environmental factors, and genetics. Poor compliance with follow-up reduced the power of the study.

Adaptability of the Immature Ocular Motor Control System: Unilateral IGF-1 Medial Rectus Treatment.

PURPOSE: Unilateral treatment with sustained release IGF-1 to one medial rectus muscle in infant monkeys was performed to test the hypothesis that strabismus would develop as a result of changes in extraocular muscles during the critical period of development of binocularity. METHODS: Sustained release IGF-1 pellets were implanted unilaterally on one medial rectus muscle in normal infant monkeys during the first 2 weeks of life. Eye position was monitored using standard photographic methods. After 3 months of treatment, myofiber and neuromuscular size, myosin composition, and innervation density were quantified in all rectus muscles and compared to those in age-matched controls. RESULTS: Sustained unilateral IGF-1 treatments resulted in strabismus for all treated subjects; 3 of the 4 subjects had a clinically significant strabismus of more than 10°. Both the treated medial rectus and the untreated ipsilateral antagonist lateral rectus muscles had significantly larger myofibers. No adaptation in myofiber size occurred in the contralateral functionally yoked lateral rectus or in myosin composition, neuromuscular junction size, or nerve density. CONCLUSIONS: Sustained unilateral IGF-1 treatment to extraocular muscles during the sensitive period of development of orthotropic eye alignment and binocularity was sufficient to disturb ocular motor development, resulting in strabismus in infant monkeys. This could be due to altering fusion of gaze during the early sensitive period. Serial measurements of eye alignment suggested the IGF-1-treated infants received insufficient coordinated binocular experience, preventing the establishment of normal eye alignment. Our results uniquely suggest that abnormal signaling by the extraocular muscles may be a cause of strabismus.

Muscimol inactivation of caudal fastigial nucleus and posterior interposed nucleus in monkeys with strabismus.

Previously, we showed that neurons in the supraoculomotor area (SOA), known to encode vergence angle in normal monkeys, encode the horizontal eye misalignment in strabismic monkeys. The SOA receives afferent projections from the caudal fastigial nucleus (cFN) and the posterior interposed nucleus (PIN) in the cerebellum. The objectives of the present study were to investigate the potential roles of the cFN and PIN in 1) conjugate eye movements and 2) binocular eye alignment in strabismic monkeys. We used unilateral injections of the GABAA agonist muscimol to reversibly inactivate the cFN (4 injections in exotropic monkey S1 with ≈ 4° of exotropia; 5 injections in esotropic monkey S2 with ≈ 34° of esotropia) and the PIN (3 injections in monkey S1). cFN inactivation induced horizontal saccade dysmetria in all experiments (mean 39% increase in ipsilesional saccade gain and 26% decrease in contralesional gain). Also, mean contralesional smooth-pursuit gain was decreased by 31%. cFN inactivation induced a divergent change in eye alignment in both monkeys, with exotropia increasing by an average of 9.8° in monkey S1 and esotropia decreasing by an average of 11.2° in monkey S2 (P < 0.001). Unilateral PIN inactivation in monkey S1 resulted in a mean increase in the gain of upward saccades by 13% and also induced a convergent change in eye alignment, reducing exotropia by an average of 2.7° (P < 0.001). We conclude that cFN/PIN influences on conjugate eye movements in strabismic monkeys are similar to those postulated in normal monkeys and cFN/PIN play important and complementary roles in maintaining the steady-state misalignment in strabismus.

Transient diplopia with ipsilateral abducent nerve palsy and ptosis following a maxillary local anesthetic injection: a case report and review of literature.

BACKGROUND: The posterior superior alveolar (PSA) nerve block is commonly used in dentistry for treatment of the maxillary molars. Although this procedure is associated with many complications, ocular complications have been rarely reported. CASE REPORT: This report details an iatrogenic paresis of the abducent nerve and partial palsy of the oculomotor nerve leading to diplopia, strabismus and ptosis following a PSA nerve block and extraction of maxillary right second molar. The patient was treated symptomatically, and the recovery was uneventful. Relevant anatomical pathways with review of literature are discussed. DISCUSSION: Although rare, the dentist should be aware of these complications to avoid being perplexed by this unexpected circumstance, thus adversely affecting the doctor-patient trust.

Skew deviation after intratympanic gentamicin therapy.

Intratympanic gentamicin therapy for the treatment of episodic vertigo associated with Ménière's disease is generally well tolerated. Although auditory and vestibular symptoms following intratympanic gentamicin are well known, visual disturbance has not been previously described. In this report, we describe two patients with Ménière's disease who developed sudden onset of binocular vertical diplopia due to skew deviation after intratympanic gentamicin therapy. The skew deviation and diplopia resolved spontaneously and completely within 6 to 8 weeks without therapy. Development of diplopia due to skew deviation should be discussed as a potential complication in patients undergoing intratympanic gentamicin therapy.

Strabismus complications from local anesthetics.

Strabismus developing after retrobulbar or peribulbar anesthesia for both anterior and posterior segment eye surgery may be due to myotoxicity to an extraocular muscle from the local anesthetic agent. Initial paresis often causes diplopia immediately after surgery, but later progressive segmental fibrosis occurs, and/or hypertrophy of the muscle, producing diplopia in the opposite direction from the direction of the initial diplopia. The inferior rectus muscle is most commonly affected. Usually a large recession on an adjustable suture of the involved muscle(s) yields good alignment. Using topical anesthesia or sub-Tenon's anesthesia can avoid this complication.

Lesión persistente de un músculo ocular motor secundaria a la inyección de toxina botulínica / Persistent injury to an ocular motor muscle secondary to injection of botulinum toxin

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The layout of functional maps in area 18 of strabismic cats.

Strabismus (or squint) is both a well-established model for developmental plasticity and a frequent clinical symptom. To analyze experience-dependent plasticity of functional maps in the brain we used optical imaging of intrinsic signals to visualize both orientation and ocular dominance domains in cat area 18. In strabismic animals, iso-orientation domains exhibited a pinwheel-like organization, as previously described for area 18 of normally raised animals and for area 17 of both normally raised and strabismic cats. In area 18, mean pinwheel density was similar in the experimental (2.2 pinwheel centers per mm2 cortical surface) and control animals (2.3/mm2 in normally raised animals), but significantly lower than in area 17 of both normally raised and strabismic cats (2.7-3.4/mm2). A comparison of orientation and ocular dominance domains revealed that iso-orientation domains were continuous across the borders of ocular dominance domains and tended to cross these borders at steep angles. Thus, the orientation map does not seem to be modified by experience-dependent changes in afferent activity. Together with our recent observation that strabismus does not enhance the segregation of ocular dominance domains in cat area 18, the present data indicate that the layout of functional maps in area 18 is less susceptible to experience-dependent manipulations than in area 17.

Heroin and diplopia.

AIMS: To describe the eye misalignments that occur during heroin use and heroin detoxification and to give an overview of the management of persisting diplopia (double vision) which results from eye misalignment. METHODS: A literature review using Medline and the search terms strabismus, heroin and substance withdrawal syndrome is presented. General management of cases presenting to the ophthalmologist and orthoptist with acute acquired concomitant esotropia is described. FINDINGS: A tendency towards a divergence of the visual axes appears to be present in heroin users, although when present it may not always lead to diplopia. Following detoxification intermittent esotropia or constant esotropia (convergence of the visual axes) can occur; if intermittent the angle tends to be small and diplopia present when viewing distance objects. Occlusion of one eye to eliminate the second image could encourage the development of a constant deviation. The deviation is not caused by a cranial nerve palsy. Constant deviations of this type are classified as 'acute acquired concomitant esotropia'. Relief from the diplopia may be gained by prismatic correction, and the deviation may then resolve spontaneously. Botulinum toxin or surgical intervention may be necessary in cases that do not resolve. CONCLUSIONS: Heroin use may lead to intermittent or constant exotropia and withdrawal may result in intermittent or constant esotropia. Awareness of the mechanism causing this may avoid referral to other specialties (e.g. neurology) and awareness of treatment modalities could encourage patients to seek appropriate help for relief of symptoms.

Inferior oblique overaction/contracture following retrobulbar anesthesia for cataract extraction with a positive Bielschowsky Head Tilt test to the contralateral shoulder. A report of one case.

BACKGROUND AND PURPOSE: This is a report of a patient with diplopia, hypertropia, extorsion and a positive Bielschowsky Head Tilt Test following retrobulbar anesthesia, due to an inferior oblique muscle overaction-contracture. CASE REPORT: Oculomotor and sensorimotor examinations and ocular motility recordings and Bielschowsky Head Tilt Test demonstrated overaction characteristics overpowering the contracture characteristics of the involved inferior oblique muscle. RESULTS: Weakening of the overacting inferior oblique eliminated the vertical and torsional deviations and the forced head tilt difference upon tilting the head to either shoulder. It also normalized ocular motility and resulted in a symptom-free patient. CONCLUSION: Oblique muscle dysfunction with vertical and torsional deviations and a positive Bielschowsky Head Tilt Test can result from retrobulbar anesthesia.

Strabismus after regional anesthesia for cataract surgery.

BACKGROUND: An adult strabismus clinic in a regional eye centre provided an opportunity to estimate the risk of postoperative diplopia from regional anesthesia after cataract surgery and to describe the management of these patients. METHODS: Retrospective cohort analysis. All cases were referred over a 22-month period (November 1997 to September 1999) for investigation of postoperative diplopia after cataract surgery. The surgical and anesthetic records were reviewed to determine the number and location of injections, and the volume and type of regional anesthesia. The evolution and management of patients' diplopia was studied prospectively. RESULTS: Twenty-one patients (12 women and 9 men aged 63 to 88 [median 76] years) were ascertained with postoperative diplopia. In 11 cases the right eye was affected, and in 10 cases, the left eye. Vertical diplopia occurred most commonly from inferior rectus restriction (16 cases). Three cases resolved without treatment, which indicated that the diplopia was transient. Four patients declined treatment, five required prism in eyeglasses only, and nine required strabismus surgery. One patient required surgery and prism in eyeglasses. Two patients required more than one strabismus operation to relieve the diplopia. For the period of data collection, we estimate the risk of nontransient postoperative diplopia from regional anesthesia as 2.6 cases per 1000 cataract procedures (95% confidence interval 1.9-4.7). INTERPRETATION: Patients should be forewarned of the risk of diplopia after cataract surgery with regional anesthesia. The treatment of the diplopia may require prism in eyeglasses or strabismus surgery or both.