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Biomedical subjects

P S O'Connor

Publications and source records attributed to P S O'Connor.

At least 19 recordsLinked to original sources
PubMed1989

Visual acuity after retrobulbar anesthesia.

Patients often say that they can see the surgical instruments with the operated eye during intraocular surgery. We examined 26 consecutive patients for visual acuity, ocular motility, and pupillary response before, during, and after retrobulbar anesthesia for cataract extraction. Twenty minutes after the anesthetic was injected, 19% of these patients had visual acuities better than 6/200, and 73% of patients described the movements of the instruments during surgery. Two patients (8%) recognized details on the ceiling after insertion of the intraocular lens. An afferent pupillary defect was found in 31% of patients. Although retrobulbar anesthesia results in a marked decrease in ocular motility and visual acuity, total akinesia and blindness do not occur. An incidental result of retrobulbar anesthesia may be a transient afferent pupillary defect.

Anesthetics, Local↗
PubMed1988

Effects of routine pupillary dilation on functional daylight vision.

The visual acuity of 100 patients between the ages of 16 and 66 years, seen for routine ophthalmologic examination, was measured before and after dilation. All patients had a predilation visual acuity of 20/40 or better. Postdilation binocular visual acuity using the patients' usual correction was measured first in the office and then outdoors, both with the patient's back to and the patient facing the sun, with and without the aid of postmydriatic sunglasses. Twelve percent experienced disabling photophobia even with the use of postmydriatic sunglasses, with 3% having significant objective visual loss defined as 20/50 or worse. No objective visual loss was found in 30 controls examined outdoors before dilation, without sunglasses. We recommend that patients who have experienced significant photophobia with dilation in the past, or who have never before undergone dilation, make arrangements for transportation after a dilated examination.

Adolescent↗
PubMed1988

Effect of cataract surgery and intraocular lenses on diabetic retinopathy.

We reviewed a series of 137 cataract extractions with intraocular lenses (IOLs) in patients with diabetes, mellitus between 1977 and 1983. All patients were followed for an average of 36 months to determine if they subsequently showed progression of diabetic retinopathy. Divided into groups according to the type of procedure and IOL received, they were compared for age, sex, duration of diabetes, treatment required for the diabetes, intraoperative complications, and follow-up period. Patients who had intracapsular cataract extractions with anterior chamber IOLs were three times as likely to show proliferative retinopathy as those who had extracapsular cataract extractions with posterior chamber IOLs. Insulin-dependent patients were three to four times more likely to show progression to proliferation than noninsulin dependent patients. We conclude that, while some procedures are riskier for the diabetic eye, extracapsular lens extraction with implantation of a posterior chamber lens does not imply an increased risk of development of proliferative retinopathy.

Aged↗
PubMed1987

Making sense of nystagmus--can it be done?

In recent years elegant recording techniques have been used to study the amplitudes, waveforms, velocities, and other characteristics of nystagmus and ocular oscillatory movement disorders. Mathematical modeling based on inferred neurophysiologic control systems and integrators have added some insight into the pathology of these conditions. From this data has developed a rather structured and complex classification system. Most specific, recognizable, localizing types of nystagmus can be diagnosed by a thorough office examination. Other types of nystagmus will be reviewed as well as those ocular movements that are oscillatory but not rhythmic and are referred to as nystagmoid movements.

Adolescent↗
PubMed1987

The pattern ERG in man following surgical resection of the optic nerve.

Pattern electroretinogram (PERG) results recorded in different laboratories from patients with unilateral traumatic transections of the optic nerve have led investigators to opposite conclusions about the sources of this response. There was no absolute demonstration of complete transection in any of these studies. In the present study, PERGs and flash ERGs were recorded from a patient who, 30 months earlier, had undergone surgical resection of the right optic nerve to remove a glioma. The histological section of the biopsied nerve confirmed complete optic nerve transection. Ophthalmoscopically and angiographically, the right eye was normal except for marked optic atrophy. PERGs were produced by 10 Hz reversal of high contrast checks with check widths from 13 deg 30 min to 12 min arc. Field size was 27 deg X 21 deg and space-averaged screen luminance was 110 cd/m2. Smaller checks (3 deg 23 min to 12 min) produced responses in both eyes, but the responses in the right eye were much smaller than those in the left eye. Large checks and diffuse flashes produced approximately equal responses in the two eyes. The implicit times of the PERGs produced by stimulation of the right eye with smaller checks were shorter than those of the left eye. The authors conclude that, in humans, there is a contribution to the high contrast pattern reversal ERG from cells which are not dependent upon the integrity of the ganglion cell layer. These cells and cells dependent upon ganglion cells may both contribute to the high contrast PERG in the normal human eye.

Adult↗
PubMed1987

Contrast sensitivity: characteristics of a large, young, adult population.

Contrast sensitivity functions and complete eye examinations were obtained from 103 normal, healthy young adults (ages 21 to 40 years). Descriptive statistics were compiled for the group in order to provide normative information. Subsets of the population were evaluated with respect to the relations among the attributes of accommodation, visual acuity, refraction, spectacle wear, and contrast sensitivity. The influence of age in this restricted population was seen only at 16 cpd. In those subjects with better than 6/6 (20/20) Snellen acuity, there were statistically significant relations with the parameters of the contrast sensitivity function as compared to those observers with 6/6 (20/20) or poorer acuity. High spatial frequency resolution was significantly better for those observers with better than 6/6 (20/20) acuity in either eye. In addition, this study provides a broad base of normative data for variability from a large population confined to a specific age range and with refractive errors that ranged from minimal to more than average.

Adult↗
PubMed1986

The effect of pilocarpine on the visual field in normals.

Despite generalized consensus that pilocarpine-induced miosis results in some degree of visual field constriction, studies describing the predictability of this occurrence, as well as the nature of the field defects that may be seen, have not been undertaken. We studied 20 normal subjects, ranging in age from 24 to 57 years. Baseline refraction, pupillary measurements, and visual fields were performed in both eyes on a standardized Goldmann perimeter with the I-2e, I-3e, and I-4e test objects. Pilocarpine 2% was then instilled into the study eye and the field repeated at 30 and 120 minutes. An IBM PC computer program, designed by the authors, was used to calculate the area contained within each isopter. The probability of visual field constriction at 30 and 120 minutes after instillation of pilocarpine was found to be significant, especially with pupillary diameters of 2 mm or less. The I-2e isopter was most sensitive to miosis. Visual field constriction persisted with correction of ciliary spasm induced myopia, suggesting that miosis, especially when marked, can independently alter the visual field. The clinician, then, should make every effort to control visual field testing conditions in glaucoma patients on miotics to allow reliable serial comparisons.

Adult↗
PubMed1986

Air travel and intraocular gas.

The safety of air travel for persons with intraocular gas after ocular surgery has been in question since the mid 1970s, when the use of intraocular gases after vitrectomy became widespread. After vitrectomy, air-fluid exchange was performed on six Rhesus monkeys. During simulated air travel in an altitude chamber, intraocular pressure rose an average of 42 mmHg with intraocular air volumes as small as 0.25 cc. Hypotony was observed after return to ground level in all cases. Transient central retinal artery occlusion and pupillary block was observed. Patient safety and comfort is endangered during air travel with very small volumes of intraocular gas.

Aircraft↗
PubMed1986

Botulinum toxin for the treatment of dysthyroid ocular myopathy.

Eight consecutive patients with acquired deviations due to dysthyroid ocular myopathy were injected with botulinum A toxin for relief of their diplopia. Seven patients were acute in the onset of symptoms and one was chronic. All showed improvement in motility and experienced a reduction if not total relief of their symptoms. Six patients required reinjection. Complications were limited to transient ptosis, transient involvement of adjacent muscles and transient but prolonged paralysis that eventually resolved. No systemic complications were noted. We conclude that chemodenervation with botulinum A toxin may have a role in the management of dysthyroid ocular myopathy not amenable to prism treatment and may act as an adjunct to or eliminate the need for surgical correction in some patients.

Adult↗
PubMed1986

Angiographically normal central retinal artery following the total resection of an optic nerve glioma.

Although the central retinal artery and its collateral circulation, especially within the anterior optic nerve, have been extensively studied, there continues to be controversy regarding the existence and significance of anastomoses between the central retinal artery and ciliary circulation. We present the case of a 16-year-old boy who underwent total resection of an optic nerve glioma beginning proximally at the chiasm and ending distally flush with the globe. After resection, heavy bipolar cautery was applied. Postoperatively, normal central retinal artery circulation was documented angiographically, suggesting that, at least in some cases, significant anastomoses can develop between the central retinal artery and ciliary circulation in the laminar and prelaminar areas.

Adolescent↗
PubMed1986

Leber's optic neuropathy and Charcot-Marie-Tooth disease. Report of a case.

The case of a patient with Charcot-Marie-Tooth disease who developed the acute fundus findings of Leber's optic neuropathy is described. Previous reports have proposed a genetic interrelationship between the two diseases. This relationship has been speculative, however, because the acute fundus findings of Leber's have never been observed in a case of Charcot-Marie-Tooth disease. This case adds support for a suggested genetic relationship between the two diseases. It is also possible that the optic atrophy previously described in Charcot-Marie-Tooth may represent the late findings of Leber's optic neuropathy.

Charcot-Marie-Tooth Disease↗
PubMed1986

New computed tomography scan finding in Hallervorden-Spatz syndrome.

The case of an 11-year-old female with the clinical findings of Hallervorden-Spatz syndrome, including progressive dystonia, dysarthria, disturbances of gait, and retinal pigmentary degeneration, is presented. The differential diagnosis of childhood dystonia and retinal pigmentary degeneration associated with neurological conditions is discussed. The presence of basal ganglia densities on computed tomography scanning in this patient may aid in future premortem diagnosis of this rare disease.

Basal Ganglia↗
PubMed1986

Cohort study of Silastic obstetric vacuum cup deliveries: II. Unsuccessful vacuum extraction.

In a cohort analysis of Silastic vacuum extractor deliveries, 65% were completed with the vacuum extractor alone, 24% with outlet forceps, 3% with midforceps, and 7% with cesarean section (vacuum extractor-cesarean). Control groups were formed by using the next sequential forceps delivery, spontaneous vaginal delivery, and every second cesarean section after a trial of labor. The infants were examined using a neurobehavioral scale, an encephalopathy assessment, cranial ultrasound, and indirect ophthalmoscopy. In the combined vacuum extractor and forceps delivery subgroup (vacuum extractor-forceps), all but 3% were converted from a high mid-forceps delivery to outlet forceps by the initial vacuum extractor procedure, thus eliminating many difficult midforceps deliveries. The study yielded no significant difference in maternal morbidity between vacuum extractor-forceps and forceps delivery, no difference in vaginal trauma for vacuum extractor-cesarean versus vacuum extractor delivery, and no greater hospital stay, infection rate, or need for transfusion for either vacuum extractor-forceps versus forceps delivery or vacuum extractor-cesarean versus cesarean delivery. Neonatal morbidity did not differ between successful and unsuccessful trial of vacuum extractor, except for an increased frequency of retinal hemorrhage. The frequency of scalp trauma, including cephalohematoma, did not differ between vacuum extractor-forceps and forceps delivery, or between vacuum extractor-cesarean and vacuum extractor delivery. For vacuum extractor-forceps versus forceps delivery and vacuum extractor-cesarean versus cesarean section, there were no significant differences in neurobehavioral or encephalopathy scores, or in the frequency of neonatal jaundice, facial palsy, anemia, fractures, or mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Cesarean Section↗
PubMed1986

Botulinum toxin for the treatment of essential blepharospasm.

Twenty-six patients with essential blepharospasm were treated with botulinum toxin by injection. The onset of protractor weakness in all patients ranged from one to five days following treatment. Maximal weakness developed within 12 days. There was a variable and gradual return of protractor strength over eight to 29 weeks in most patients and, with it, a return of spasm. Twenty-five patients received some degree of functional relief following initial injection. In most patients, however, the post-injection result could not be stabilized and repeat injections have been necessary to control recurrent spasms. There was one treatment failure. Three patients treated by injection following previous neurectomy and myectomy appeared to have a reduced requirement for subsequent injections. Complications included transient ptosis in six patients and mild exposure symptoms in four patients. Extraocular muscle paresis did not occur. There were no systemic side effects from the botulinum toxin injections.

Aged↗
PubMed1985

Vitamin E deficiency associated with vision loss and bulbar weakness.

We describe a 14-year-old boy who was severely debilitated by the neurological syndrome associated with vitamin E deficiency secondary to chronic cholestatic liver disease. In addition to the usual neurological deficits described with this deficiency, the patient had severe bulbar weakness and vision loss which we attribute to the degree and duration of his vitamin E deficiency. Vitamin A deficiency may have contributed to his visual disturbance. Early recognition of vitamin E deficiency is important, as the neurological and visual disorders which result are treatable.

Adolescent↗
PubMed1985

Voluntary alteration of pattern visual evoked responses.

Pattern and flash visual evoked responses (VERs) were recorded from a large group of ophthalmologically normal subjects during two conditions: in one they were instructed to attend to the stimulus and in the other they were instructed to ignore the stimulus but maintain their gaze on the stimulus. Pattern VERs were recorded from 42 subjects. Fixation was constantly monitored during both attend and ignore conditions and no changes of fixation were noted at any time. The amplitude of the major positive wave of the pattern VERs produced by both 50- and 25-min checks was reduced significantly during the ignore condition. The implicit time of this positive wave did not differ significantly during the two conditions. The pattern VERs of eight subjects were extinguished and the VERs of another three subjects were unrecognizable during the ignore condition. Flash VERs produced by 10 flashes per second were recorded from 38 of the 42 subjects. There were no significant differences between the amplitudes recorded during the attend and ignore conditions.

Adult↗
PubMed1985

Extraocular muscle size comparison using standardized A-scan echography and computerized tomography scan measurements.

In many clinical situations, the standard for evaluating extraocular muscle (EOM) size, particularly in thyroid ophthalmopathy, has been use of the computerized tomography (CT) scanner. The impression is generally reported as "enlarged or normal EOMs." If the report of "normal EOM" on CT scan weighs heavily against the diagnosis of thyroid eye disease, how does this qualitative assessment compare with the diagnostic modality of ultrasound? The technique of standardized A-scan measurement of extraocular muscles has been extremely accurate. In this paper, standardized A-scan measurements and CT scan estimates of EOMs are compared in a series of ten patients with a clinical diagnosis of Graves' disease. Three of ten patients displayed enlarged EOMs by CT interpretations; seven of ten patients were categorized as consistent with Graves' disease by correlation with current ultrasonographic criteria for muscle enlargement, asymmetry, and high irregularity of tissue reflectivity.

Exophthalmos↗