David H. Zackon

Symptomatic and asymptomatic visual loss in patients taking vigabatrin

PURPOSE To investigate the clinical, perimetric, and electrophysiologic findings in patients with visual field loss on long-term treatment with the antiepileptic medication vigabatrin. DESIGN Consecutive observational case series. PARTICIPANTS Forty-one consecutive subjects taking vigabatrin referred for screening ophthalmologic assessment were studied. Twelve subjects with evidence of peripheral visual field constriction are presented. METHODS Twelve subjects with evidence of peripheral visual field constriction on 60-4 perimetry underwent central 30-2 and blue-on-yellow (B/Y) perimetry, as well as electroretinography (ERG), electro-oculography (EOG), and visual-evoked potential (VEP) testing. MAIN OUTCOME MEASURES Visual acuity; fundus abnormalities; visual field loss; and ERG, EOG, or VEP abnormalities were the main outcome measures. RESULTS Eight of the 12 subjects with constricted visual fields were asymptomatic. The central 30-2 perimetry demonstrated bilateral visual field constriction in 9 of 12 patients and the B/Y perimetry in 8 of 9 patients tested. Of the ten patients tested electrophysiologically, four had abnormal ERGs, five had abnormal EOGs, and three had delayed VEPs. CONCLUSIONS The incidence of visual field constriction in patients taking vigabatrin may be higher, and asymptomatic visual field loss more common, than reported previously. The authors postulate a possible Muller cell dysfunction in the peripheral retina. Patients taking vigabatrin should have regular peripheral visual field examinations.

Vigabatrin effect on inner retinal function

OBJECTIVE To determine the degree of electroretinal dysfunction in a group of patients taking Vigabatrin (VGB). Additionally, to investigate the role of cumulative dosage, the role of VGB alone or in combination with other anticonvulsants, and whether recent discontinuance of VGB affects electroretinal function as measured by the electroretinogram (ERG). DESIGN Retrospective, comparative case series. PARTICIPANTS Forty patients (18 male, 22 female) with a mean age of 35 years were studied as three groups: the VGB multitherapy group (n = 24) included those taking VGB with other anticonvulsants, the VGB monotherapy group (n = 9) included those taking VGB alone, and the off-VGB group (n = 7) included those who had discontinued VGB in the last 6 months. METHODS Scotopic flash, photopic flash, and 30-Hz flicker ERG results were recorded according to the International Society for Clinical Electrophysiology of Vision (ISCEV) standard. The clinical electro-oculogram (EOG) results were recorded according to the ISCEV standard. MAIN OUTCOME MEASURES Implicit time and amplitudes of the A- and B-waves of the flash and 30-Hz flicker ERGs were recorded. Summed amplitude of the first three oscillatory potential wavelets were recorded. The light-peak to-dark-trough Arden ratio of the EOG was evaluated. RESULTS Although photopic ERG B-wave reduction was most frequent in patients in the VGB multitherapy group (48% of eyes), a significant number of eyes in all three groups had scotopic ERG B-wave reduction. The 30-Hz flicker ERG result was abnormally reduced in all three groups. There was no significant difference in the frequency of occurrence in ERG result abnormalities between the VGB monotherapy and VGB multitherapy groups. The EOG results revealed reduced Arden ratios in all three groups; however, there was a significantly lower frequency of EOG abnormalities noted in the off-VGB group (P = 0. 0373). There was no statistically significant relationship between the frequency of electrodiagnostic abnormalities and the duration of use or the total cumulative dosage of Vigabatrin in any of the three groups. CONCLUSIONS These findings of scotopic ERG result abnormalities suggest that VGB alone has an effect on inner electroretinal function at the level of the Müller cell. Concomitant EOG abnormalities suggest a substantial effect of VGB on outer retinal function that may be reversible after cessation of VGB treatment.

The temporal order judgment paradigm : subcortical attentional contribution under exogenous and endogenous cueing conditions

The role of subcortical attentional processing was investigated under exogenous and endogenous cueing conditions. As retinotectal projections arise predominantly from the nasal retina i.e., temporal hemifield, subcortical attention should be distributed asymmetrically under monocular viewing conditions with a temporal hemifield advantage. We compared the results of monocular and binocular viewing conditions using a temporal order judgment (TOJ) paradigm. Subjects fixated a centrally located cross and two stimuli were presented with a variable onset asynchrony. Three experiments were conducted: no cue, exogenous cue and endogenous cue. Subjects reported which stimulus seemed to appear first. An effect consistent with subcortical processing was found under exogenous cueing conditions. No such effect was found under endogenous cueing conditions. We believe that subcortical attentional processing in response to an exogenous cue facilitates rapid shifts in attention towards environmental stimuli. We found no evidence for subcortical processing in voluntary directed attention and believe this process to be cortical in nature.

Smooth pursuit during dose‐related on‐off fluctuations in Parkinson's disease

Smooth pursuit was studied during predictable L-dopa dose-related “OR” periods of morning akinesia and wearing off and during “on” periods in eight patients with idiopathic Parkinsons disease. Smooth pursuit gain was significantly reduced in patients during both on and off phases. Despite marked fluctuations between parkinsonism and periods of near normal skeletal motion, there were no changes in smooth pursuit gain. We conclude that unvarying paresis of smooth pursuit in Parkinsons disease signifies involvement of neural circuits that are distinct from the dopaminergic mechanisms that mediate the on-off phenomenon of somatic motor control.

An investigation of the visual disturbances experienced by patients on clomiphene citrate

OBJECTIVE To evaluate the impact of clomiphene citrate on vision. DESIGN Observational study. SETTING Patients were referred to the University of Ottawa Eye Institute ophthalmology clinic from the Department of Obstetrics and Gynaecology of the Ottawa Hospital-General Campus. PATIENT(S) Eight adult females taking clomiphene citrate and experiencing visual disturbances. INTERVENTION(S) Patients received a comprehensive visual evaluation twice: once during a washout period, and once during an active clomiphene citrate treatment. MAIN OUTCOME MEASURE(S) Ophthalmologic examination, color vision, visual acuity, contrast sensitivity, visual fields using standard automated perimetry, and foveal flicker sensitivity at high (32 Hz) and low (8 Hz) temporal frequencies. RESULT(S) We found no differences between the washout and clomiphene citrate conditions for color vision, visual acuity, contrast sensitivity, and visual fields. The only statistically significant difference was found for foveal flicker sensitivity at 32 Hz in the right eye, with a similar trend in the left eye and at 8 Hz in both eyes. CONCLUSION(S) The effect of clomiphene citrate on vision was minimal, and the visual disturbances were reversible in all patients. A bilateral reduction in flicker sensitivity was the only observed visual disturbance. Women who experience visual symptoms associated with clomiphene citrate should be monitored, but therapy can usually be maintained.

Lymphocytic hypophysitis with a long latent period before development of a pituitary mass.

BACKGROUND Lymphocytic hypophysitis is an autoimmune condition that commonly presents in women of childbearing age as hypopituitarism and a sellar mass. CASE REPORT A 66-year-old woman presented with anterior pituitary dysfunction. Computed tomography imaging revealed a small hypodensity that was not felt to be the cause of the pituitary dysfunction. Eight years later, her vision rapidly deteriorated and MRI showed a pituitary mass lesion causing optic chiasm compression. Histological examination of the partially resected gland revealed evidence of lymphocytic hypophysitis. CONCLUSION Our patient is an example of the variable presentation and course of lymphocytic hypophysitis. Such a long latent period between the initial presentation of adenohypophysial hypofunction and optic chiasm compression due to an enlarging pituitary mass has not been reported.

Neuroretinitis with Branch Retinal Artery Occlusion in a 15-Year-Old Female

We report a case of Bartonella henselae neuroretinitis with significant disc and peripapillary edema, branch retinal artery occlusion without macula involvement and well preserved central vision. A 15-year-old female presented with loss of vision over 4 weeks in the left eye. She had a history of cat exposure, but a cat scratch, insect bite or conjunctivitis was not reported. An inferotemporal arcuate scotoma developed during the acute phase and persisted over the course of the follow-up.

Periorbital complex regional pain syndrome

Fig. 2—(A) Periorbital edema in the right eye and mild lower left lid edema improving 3 days after administration of intravenous methylprednisone and a daily tapered dose of oral prednisone (80 mg). (B) Resolving edema in both eyes at 3 weeks after the first presentation. Complex regional pain syndrome (CRPS) is characterized by disproportionate pain in relation to the severity of the inciting stimulus and presents with sensory, autonomic, trophic, or motor abnormalities. Most reported cases of CRPS relate to limb injury, with few cases described in the head and neck region. We summarize all cases of orbital CRPS described in the literature to date and report a case of periorbital CRPS. A 25-year-old female patient presented with a 3-day history of spontaneous right lower lid and facial edema, severe pain with extraocular movements, skin discoloration, warmth, and hyperalgesia to light and deep touch in the right periorbital area. She had no symptoms suggestive of sinusitis (Fig. 1). Her best-corrected visual acuity was 20/20 with normal intraocular pressure bilaterally. Pupils were equal and reactive to light, and there was no afferent pupillary defect. The anterior and posterior segments were unremarkable. Computed tomography of the head revealed periorbital edema with no orbital involvement and no sinus opacification. She was treated empirically with intravenous (IV) ceftriaxone (1 g daily) and clindamycin (60 mg IV q8h) for 3 days. On day 4, the periorbital edema had improved slightly. The patient was discharged on 14 days of oral cloxacillin (500 mg four times a day) and antihistamines. Two weeks later, she was admitted with worsening right periorbital edema with no change in her ocular examination findings. Magnetic resonance imaging showed no evidence of orbital involvement, no cavernous sinus involvement, and no fluid collection. One day later, there was new lower lid edema in the left eye. The patient was subsequently treated with an empiric course of IV methylprednisone (500 mg) and started on a daily course of oral prednisone (80 mg) tapered by 10 mg every 3 days. One week later, her symptoms improved significantly, with full resolution at 6-month follow-up (Fig. 2). The patient’s ocular history was significant for 3 childhood episodes of self-resolving bilateral periorbital edema caused by traumatic local injuries when she was between 12 and 18 years of age, with normal findings on imaging studies. Her medical history was significant for ongoing lower limb CRPS since age 10 years secondary to trauma managed with benzodiazepines, opioids, nonsteroid antiinflammatory drugs (NSAIDs), psychotherapy, real-life simulation exercises, and a trial of spinal cord stimulation. She also had developed spontaneous left upper extremity compartment syndrome at age 22 years, which was managed with delayed closure fasciotomies at that time (Fig. 3). CRPS is a painful disorder that usually develops after trauma. The heterogeneity of disease presentation and scarcity of relevant research has led to contsdroversy surrounding diagnosis of CRPS. The original International Association for the Study of Pain (IASP) diagnostic criteria event, continuing sensory changes, and vasomotor abnormalities with no alternative diagnoses. These criteria were revised in 2007 to outline 4 categories of symptoms: hyperalgesia or allodynia, temperature or color changes, edema, and motor or trophic changes. Subsequently, modified diagnostic criteria were developed to differentiate between CRPS and non-CRPS neuropathic pain. As per the new guidelines, CRPS can be diagnosed only if there is (i) continuing pain disproportionate to the inciting event; (ii) at least 1 of sensory (hyperalgesia, allodynia), vasomotor (temperature asymmetry/skin or color changes), edema, or motor/trophic symptoms; (iii) at least 1 sign at the time of evaluation in 2 or more of sensory, vasomotor, edema, or motor/trophic changes; and (iv) exclusion of alternative diagnoses. Our patient met these criteria with respect to pain with eye movements,