Peribulbar Corticosteroids for Ocular Myasthenia Gravis.

BACKGROUND: Ocular myasthenia gravis is treated predominantly by oral medications, with the potential for systemic adverse effects. Successful treatment has been achieved using peribulbar dexamethasone. We assessed the effect of peribulbar dexamethasone or triamcinolone (40-mg Triesence), a longer-acting corticosteroid, targeting the peribulbar area as opposed to directly injecting the affected extraocular muscle. This more convenient and secure approach holds the potential for straightforward integration within clinical environments. METHODS: Retrospective chart review. RESULTS: Five patients were identified that were treated with peribulbar corticosteroids. In 4 of the 5 cases, ophthalmoparesis was unilateral. One case had isolated ptosis, and 4 had both ptosis and ophthalmoparesis. Three of these 4 cases reported complete resolution of symptoms within weeks of a single injection. Improvement lasted between 5 to 6 months, and all patients responded to repeated injections. CONCLUSIONS: Peribulbar corticosteroids can be effective in ocular myasthenia gravis. We suggest that longer-acting agents such as triamcinolone are preferable, to reduce injection frequency.

Decompensated Superior Oblique Palsy Secondary to Bilateral Nutritional Optic Neuropathy Following Bariatric Surgery.

Optic neuropathy can occur secondary to nutritional deficiencies in patients who have undergone bariatric surgery. We present a unique case of a 39-year-old man, claiming to be generally healthy, who presented with intermittent vertical diplopia and bilateral decreased vision in each eye. Visual acuity was 6/18 in the right eye and 6/12 in the left eye. Ishihara testing was defective for both eyes. Automated visual fields showed a severe generalized reduction in sensitivity in both eyes. The patient had a left head tilt and a right intermittent hypertropia of 30 prism diopters in primary position. CT of the orbits revealed a right superior oblique of small caliber. On further questioning, the patient admitted to a history of bariatric surgery 7 years prior to presentation with failure to take any nutritional supplements. Blood work demonstrated deficiencies in folate, thiamine, and copper. Within 6 months of initiating nutritional supplements, the vision in each eye was markedly improved and the diplopia resolved. There was an associated normalization of thiamine and copper, but folate levels remained low. We believe that the nutritional deficiency caused a bilateral optic neuropathy and the resulting vision loss precipitated a manifestation of a congenital superior oblique palsy that had previously just been a phoria. The case emphasizes the importance of considering occult sensory etiologies of acquired strabismus.

The "Crab" Memory Tool for the Actions of the Extraocular Muscles.

INTRODUCTION: Understanding the primary, secondary and tertiary actions of the vertical recti and oblique muscles is important in the diagnosis of various types of strabismus (superior oblique palsy, A- and V-patterns). Unfortunately, learning these actions can be very challenging. We designed a visual memory tool, and assessed its usefulness for medical students. METHODS: Medical students undergoing their rotation in ophthalmology were taught the actions of the extraocular muscles either without the memory aid (control group) or with it (test group). The students were surveyed one week and one month later to determine their ability to recall the muscle actions and asked to subjectively rate the usefulness of the memory aid. RESULTS: Approximately 40% of the test group used the memory tool. Eighty-seven percent of the respondents recommended that the memory aid be taught in the future. Overall, there was no significant difference in the ability to recall the actions of the muscles between the control and test groups. However, those students who found the memory aid helpful had significantly better recall than those who did not. CONCLUSION: The memory aid may be useful to a significant proportion of students.

Systematic approaches for reviewing neuro-imaging scans in ophthalmology.

Neuroimaging is an important tool in ophthalmology, but many ophthalmologists are uncomfortable evaluating actual scans. Unfortunately, exclusive reliance on a radiologist's report can lead to diagnostic and management errors. We outline a methodology for equipping ophthalmologists with the skills necessary to read neuroimaging studies with respect to specific clinical questions.

Low-Density Lipoprotein Receptor-Related Protein 4-Positive Myasthenia Gravis in a Double-Seronegative, Electromyography-Negative Patient.

We describe a patient with ocular myasthenia gravis, where single-fiber electromyography and testing for acetylcholine receptor and muscle-specific kinase antibodies were negative. However, antibodies to low-density lipoprotein receptor-related protein 4 (LRP4) were positive, and this prompted appropriate management. We recommend that testing for LRP4 antibodies be considered when the clinical suspicion for myasthenia gravis is high despite negative conventional diagnostic tests.

Vestibular Schwannoma Presenting with Bilateral Papilledema Without Hydrocephalus: Case Study.

Bilateral papilledema secondary to obstructive or communicating hydrocephalus in patients with vestibular schwannomas is a known presentation; however, papilledema in the absence of hydrocephalus is rarely reported and its mechanism is poorly understood. We report a case of a 20-year-old woman presenting with visual deterioration and bilateral papilledema on fundoscopy. Magnetic resonance imaging (MRI) revealed a giant vestibular schwannoma with no sign of hydrocephalus. The only imaging evidence of increased pressure on preoperative imaging studies was seen on a T2-weighted MRI, where there was subtle dilatation of the arachnoid space of the optic sleeve. We presume that this patient developed papilledema by some mechanism not connected to hydrocephalus. In a young patient, papilledema may be a sign preceding hydrocephalus, or she may have had pseudotumor cerebri concomitant with her vestibular schwannoma. In either case, removal of the vestibular schwannoma solved the problem. She had complete visual recovery, irrespective of the mechanism.

Ocular flutter as the presenting sign of lung adenocarcinoma.

Ocular flutter is a rare ophthalmic finding that could represent paraneoplastic phenomena. In adults it is most commonly associated with small cell lung cancer (SCLC). Most patients also present with other neurological defects. We report the case of a 75-year-old woman who presented with isolated ocular flutter. The ensuing workup was significant for an early lung adenocarcinoma that would not have been biopsied otherwise due to its small size. To our knowledge, this is the first reported case of isolated ocular flutter as the presenting symptom of non-SCLC.

Neuro-imaging: a review for the general ophthalmologist.

The diagnosis of many neuro-ophthalmic conditions is facilitated with neuro-imaging. The two main modalities are Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). Clinicians who refer patients for either of these techniques must not only know which of them to choose, but also where the imaging should be performed (e.g. brain, orbit), whether or not contrast is indicated, and if angiography should be supplemented. These complexities often result in imaging studies that are either unneeded or unhelpful. The goal of this manuscript is to provide a practical set of guidelines for the general ophthalmologist of how to choose the correct parameters for neuro-imaging studies.

Protein-tyrosine phosphatase MEG2 is expressed by human neutrophils. Localization to the phagosome and activation by polyphosphoinositides.

Signaling pathways involving reversible tyrosine phosphorylation are essential for neutrophil antimicrobial responses. Using reverse transcriptase PCR, expression of the protein-tyrosine phosphatase MEG2 by peripheral neutrophilic polymorphonuclear leukocytes (PMN) was identified. Polyclonal antibodies against MEG2 were developed that confirmed expression of MEG2 protein by PMN. Through a combination of immunofluorescence and cell fractionation followed by immunoblotting, we determined that MEG2 is predominantly cytosolic with components present in secondary and tertiary granules and secretory vesicles. MEG2 activity, as determined by immunoprecipitation and in vitro phosphatase assays, is inhibited after exposure of cells to the particulate stimulant opsonized zymosan or to phorbol 12-myristate 13-acetate but largely unaffected by the chemoattractant N-formyl-methionyl-leucyl-phenyalanine. Studies using bacterially expressed glutathione S-transferase MEG2 fusion protein indicate that cysteine 515 is essential for catalytic activity, whereas the noncatalytic (N-terminal) domain of MEG2 negatively regulates the enzymatic activity of the C-terminal phosphatase domain. The activity of MEG2 is enhanced by specific polyphosphoinositides with the order of potency being phosphatidylinositol (PI) 4,5-diphosphate > PI 3,4,5-triphosphate > PI 4-phosphate. MEG2 associates at an early stage with nascent phagosomes. Taken together, our results indicate that MEG2 is a polyphosphoinositide-activated tyrosine phosphatase that may be involved in signaling events regulating phagocytosis, an essential antimicrobial function in the innate immune response.