Stress distributions are presented for a normal and a restored mandibular second premolar under masticatory-type forces. These were obtained using the finite element method of stress analysis applied to two-dimensional models. The effect of the relative stiffness of the materials is examined in each instance.

Bicuspid↗

PubMedDate not supplied

Finite element stress analysis of a class I amalgam restoration subjected to setting and thermal expansion.

Stress analyses are presented for a second mandibular premolar with a class 1 amalgam restoration. The effects of amalgam setting and thermal expansions are examined. An axisymmetric representation of the structure is used and the analyses are carried out by the finite element method. Lined and unlined restorations are compared with regard to the principal stresses set up in the composite structures and also the patterns of deformation incurred. The effects of various enamel and dentin stiffness combinations are also considered.

Chemical Phenomena↗

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Weill-Marchesani syndrome with bilateral angle-closure glaucoma.

To our knowledge this is the first reported case of cyclopentolate induced bilateral acute angle-closure glaucoma associated with the Weill-Marchesani syndrome without lens subluxation. The diagnosis of Weill-Marchesani syndrome was not initially suspected, and Pilocarpine was used in an attempt to break the acute attack. Treatment with Pilocarpine-induced myosis only worsened the glaucoma by causing a severe pupillary block. This case is important because it demonstrates that mid-dilatation and cycloplegia can induce acute glaucoma in patients with the Weill-Marchesani syndrome and points out the importance for considering the diagnosis of Weill-Marchesani syndrome in any case of acute glaucoma in childhood.

Abnormalities, Multiple↗

PubMedDate not supplied

Suppression and the pattern visual evoked potential.

We assessed the effect of amblyopic suppression on the pattern visual evoked potential (P-VEP). Since anisometropic amblyopia is associated with the monofixation syndrome and a central suppression scotoma in the amblyopic eye, patients with this functional defect were used for the study. Five anisometropic amblyopes and four normal subjects were studied using the P-VEP test. A modified haploscope was used to present a pattern stimulus to the area of suppression. By comparing responses generated under monocular conditions (non-suppression) with monocular responses under binocular viewing conditions (suppression), we measured the effect of suppression on the P-VEP. Our results show that amblyopic suppression completely abolishes P-1 amplitudes in patients with large suppression scotomas; in patients with small suppression scotomas the P-1 amplitudes were greatly reduced. Rivalry in normals also caused a reduction in P-1 amplitudes, but to a much lesser degree than that associated with anisometropic suppression. Patients with significant amblyopia did not show a rivalry effect on the P-VEP. Because the P-1 wave of the transient P-VEP is thought to represent activity at the level of the striate cortex, our results indicate that suppression probably occurs at the striate cortex or lateral geniculate nucleus.

Amblyopia↗

PubMedDate not supplied

Detection of amblyopia with P-VEP during chloral hydrate sedation.

A major limitation of methods presently used for detecting amblyopia in preverbal children and infants is their dependence on patient cooperation. In response to this problem, we have introduced the use of chloral hydrate sedation as a means of obtaining the pattern visual evoked potential (P-VEP) in uncooperative infants. Twenty-five infants were studied: 14 with clinically diagnosed amblyopia, four with questionable amblyopia, and seven with no clinical sign of amblyopia. In patients with known amblyopia, P-1 amplitudes from the amblyopic eye were greatly diminished when compared with responses obtained from the non-amblyopic fellow eye, with amplitude ratios ranging from 0 to 0.66 (mean 0.36). In contrast, P-1 responses from non-amblyopic infants were quite symmetrical, with amplitude ratios of 0.82 to 0.98 (mean 0.92). These results indicate that the P-VEP can be obtained during chloral hydrate sedation and that P-1 responses reflect the presence or absence of amblyopia. Performing P-VEP during chloral hydrate sedation thus holds promise as an important clinical tool for the diagnosis of amblyopia in uncooperative infants and children.

Amblyopia↗

PubMedDate not supplied

Attachment for the Bausch & Lomb keratometer in pediatrics.

Explore the source record for details and available documents.

Cornea↗

PubMedDate not supplied

Superimposition of a cartoon program as an aid in recording pattern visual evoked potentials in children.

Superimposition of a television program onto the black and white checkerboard stimulus used in performing the pattern visual evoked potential (P-VEP) has been found useful in testing adults and children. This study tested normal-vision children under two conditions: with the cartoon superimposition and with the standard black and white checkerboard. P100 amplitudes were decreased slightly with the superimposition, but the variability was not significantly different. Waveforms and latencies were not altered by the addition of the cartoon. The use of cartoon superimposition therefore can be helpful in maintaining attention during P-VEP testing in children, as long as the diminished amplitude characteristic is taken into account.

Caricatures as Topic↗

PubMedDate not supplied

Congenital toxoplasmosis presenting as isolated acute chorioretinitis in the neonate.

We describe a neonate with congenital ocular toxoplasmosis that presented as isolated, acute bilateral retinochoroiditis. Although toxoplasmic retinochoroiditis is not rare, it is quite unusual to diagnose congenital toxoplasmosis based on isolated bilateral retinochoroiditis in an otherwise healthy neonate. Bilateral retinochoroiditis can be caused by syphilis, herpes virus, cytomegalovirus, and toxoplasmosis. Because specific treatments now exist for these conditions, it is important to establish proper diagnosis so that treatment can be initiated promptly. The differential diagnosis, work-up, and management of retinochoroiditis in the newborn is presented and discussed.

Chorioretinitis↗

PubMedDate not supplied

PVEP evidence of true suppression in adult onset strabismus.

Customarily, it is taught that strabismus acquired in childhood results in suppression of the diplopic image, whereas strabismus acquired in adulthood causes diplopia or conscious image ignoring, but not true cortical suppression. The pattern visual evoked potential (PVEP) was recorded from strabismic patients, three with childhood onset, two adult onset with diplopia, and three with longstanding adult onset strabismus "ignored" diplopia. Patients with childhood onset and adult onset "ignored" diplopia similarly showed essentially no response under haploscopic stimulation, whereas patients with diplopia and normal control subjects showed a 50% decrease (rivalry). These results suggest that adults with acquired strabismus who "ignore" the diplopic image actually have a suppressed cortical visual activity, as evidenced by the pattern visual evoked potential.

Adolescent↗

PubMedDate not supplied

Use of high dose chloral hydrate for ophthalmic exams in children: a retrospective review of 302 cases.

Although chloral hydrate sedation has been proposed as an alternative to evaluation under anesthesia for pediatric patients who are unable to cooperate with routine test procedures, a careful study of the drug's safety and effectiveness is lacking. This study reports the effectiveness and safety of high-dose chloral hydrate for ophthalmic examination in 302 patients between the ages of 1 month and 5 years. The patients had nothing to eat or drink for 4 hours prior to drug administration. The patients were monitored during sedation and until fully awake. Eighty-eight percent of the patients (266/302) were successfully sedated without a supplemental dose. There were no reports of any complications including emesis, respiratory distress or depression, behavioral problems, changes in vital signs, patient injury, or hospital admission. The high-dose chloral hydrate protocol described, results in safe and generally successful sedation of pediatric patients for ophthalmic examination.

Child, Preschool↗

PubMedDate not supplied

Effect of a modified rectus tuck on anterior segment circulation in monkeys.

Removal of a rectus muscle results in permanent interruption of blood flow in the corresponding anterior ciliary artery, predisposing to anterior segment ischemia (ASI). A subhuman primate model of ASI was developed in order to study a novel muscle tuck procedure designed to preserve anterior ciliary artery circulation. Fluorescein angiograms were obtained before and after surgery to determine the effect of the muscle surgery on iris circulation. A total of 12 eyes from 12 cynomolgus monkeys underwent strabismus surgery consisting of tenectomy of all 4 rectus muscles in 3 eyes, tenectomy of 3 rectus muscles in 3 eyes, and tenectomy of 3 rectus muscles and muscle to sclera tuck of the remaining recti in 6 eyes. Postoperative angiograms documented preservation of perfusion in the distribution of the tucked muscle in all cases except one, in which there was iatrogenic trauma and disruption of anterior ciliary arteries. The modified tuck procedure thus appears to preserve anterior ciliary artery blood flow, and may be useful as a muscle strengthening procedure in patients predisposed to developing ASI.

Animals↗

PubMedDate not supplied

Superior oblique silicone expander for Brown syndrome and superior oblique overaction.

Standard procedures for weakening the superior oblique muscle have been associated with significant complications in the treatment of superior oblique overaction and Brown syndrome. This article presents a new technique for weakening the superior oblique muscle by lengthening the superior oblique tendon. Lengthening is accomplished by a nasal superior oblique tenotomy, and by inserting a segment of medical grade silicone 240 retinal band between the cut ends of the tendon. This technique was performed on 18 patients (30 eyes), 14 (26 eyes) with superior oblique overaction, and four (one eye each) with Brown syndrome. Preoperatively, patients with superior oblique overaction demonstrated A-patterns between 20 prism diopters and 55 delta, and versions of +2 to +4 superior oblique overaction in at least one eye. Postoperatively, the A-pattern and overaction improved in each case, and 13 of the 14 patients had patterns 10 delta or less. Of the four patients with Brown syndrome, three showed marked improvement of elevation in adduction, without consecutive superior oblique palsy. One had no improvement, even after a second procedure, consisting of superior oblique tenectomy; this case probably represents a non-superior oblique restriction (ie, a pseudo-Brown syndrome). Based on these results, it appears that the silicone expander technique is useful in patients with superior oblique overaction and Brown syndrome secondary to tight superior oblique tendon. This technique allows a predetermined degree of tendon separation and a graded weakening of the superior oblique muscle. Furthermore, by controlling the cut ends of the tendon, the procedure is easily reversible and there is ready access to the tendon should reoperation be necessary for residual overaction.

Adolescent↗

PubMedDate not supplied

Comparison of superior oblique tendon expander to superior oblique tenotomy for the management of superior oblique overaction and Brown syndrome.

We compared surgical results of superior oblique tenotomy to the superior oblique silicone expander for the treatment of superior oblique overaction and Brown syndrome. Of 24 patients with bilateral superior oblique overaction, 13 underwent tenotomy and 11 had the silicone expander procedure. Reduction of A-pattern to within 10 prism diopters was achieved in 12/13 (92.3%) tenotomy patients and in 10/11 (90.9%) patients undergoing silicone expander (P greater than .05). Correction of superior oblique overaction on versions to within +/- 1 dysfunction was achieved in 22/26 (84.6%) of the tenotomies, and 21/22 (95.5%) silicone expander procedures (P greater than .05). Zero superior oblique dysfunction was found after 14/26 (53.8%) tenotomy procedures versus 18/22 (81.8%) silicone expander operations (P = .041). Superior oblique paresis occurred postoperatively in 4/13 (30.8%) tenotomy patients, whereas none of the 11 patients in the silicone expander group had superior oblique paresis (P = .044). Six patients who underwent superior oblique tenotomy for superior oblique overaction had preoperative stereopsis; following surgery, only two maintained the same level of stereopsis, and three patients totally lost all stereo acuity. All patients in the silicone expander group either maintained or had improved stereo acuity postoperatively. Seven patients with true Brown syndrome were operated on: three underwent the silicone expander procedure and four had a superior oblique tenotomy with an ipsilateral inferior oblique recession. The combination of superior oblique tenotomy with simultaneous ipsilateral inferior oblique recession resulted in an undercorrection in two of the four patients, whereas all three patients in the silicone expander group showed excellent ocular motility postoperatively, with two having normal versions and one a -1 residual limitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗