Biomedical subjects

J H Calhoun

Publications and source records attributed to J H Calhoun.

116 records · Page 7Linked to original sources

PubMedDate not supplied

Reoperations for esotropia.

The results of bilateral medial rectus rerecession and bilateral lateral rectus resection for patients with undercorrected or recurrent esotropia after medial rectus recession are compared. Medial rectus rerecession resulted in a high rate of consecutive exotropia. Lateral rectus resection was more accurate but was often accompanied by undercorrection. Minimal millimeter amounts of rerecession yielded large diopter results. Except in cases where medial restrictive factors or obvious errors in magnitude of the original surgery are noted, we feel that bilateral lateral rectus resection is the surgery of choice in patients with recurrent or undercorrected esotropia following medial rectus recession.

Esotropia↗

PubMedDate not supplied

Measurement of vertical deviations in different gaze positions in patients with a superior oblique palsy.

Objective measurements in eight consecutive patients with an isolated congenital superior oblique palsy using a head tilt technique, with gaze directed toward a fixed distance target, and a second technique with gaze directed at a movable near object in different fields of gaze each identified the same oblique position of maximal vertical deviation. We call the latter technique "field-directed." In distinction to the controversy that exists as to which method correctly diagnoses an isolated superior oblique palsy, either technique can be used to direct the surgical correction of this palsy. Superimposing a head tilt on the field-directed technique affected measurements in 16 of the 20 instances where tested. Despite the necessity of avoiding an inadvertent head tilt the field-directed technique is considerably easier to perform and more comfortable for the patient to endure in determining the position of maximal vertical deviation.

Adolescent↗

PubMedDate not supplied

One versus two simultaneous goniotomies as the initial surgical procedure for primary infantile glaucoma.

To evaluate whether a more extensive incision of the tissue adjacent to the anterior trabecular meshwork resulted in more effective control of intraocular pressure (IOP), seven infants with bilateral congenital glaucoma underwent a single goniotomy in one eye and two simultaneous goniotomies at separate sites in the second. Sodium hyaluronate (Healon) was used in all eyes undergoing two simultaneous goniotomies and in three to seven eyes undergoing a single goniotomy. Success was not significantly different, at 1 month or 1 year postoperatively, for eyes which underwent two simultaneous and separate goniotomies. Successful control of IOP was, however, related to the preoperative IOP. Eyes for which the initial procedure was unsuccessful had a significantly higher IOP. The incidence of postoperative hyphemas was less in eyes in which the Healon was used intraoperatively, but the use of Healon did not favorably or adversely affect intraocular pressure control.

Eye Diseases↗

PubMedDate not supplied

Visual pathway abnormalities in albinism and infantile nystagmus: VECPs and stereoacuity measurements.

The visual pathway of albinos is characterized by abnormal optic nerve fiber decussation with increased contralateral projection. This results in hemispheric asymmetry of monocular visually evoked cortical potentials (VECPs) and may be related to lack of stereopsis. Flash VECP, Random Dot E (RDE), and Titmus stereotest data were collected from 40 nystagmus patients, 19 albino and 21 with normal pigmentation. Data were compared with results obtained from 19 race- and age-matched normal subjects. All albino patients demonstrated hemispheric VECP asymmetries exceeding +/- 2.0 standard deviations from the normal mean, showing either delayed ipsilateral P latency (88%), reduced ipsilateral P amplitude (59%), or both (47%). None of the normally pigmented infantile nystagmus patients exceeded this criteria on either VECP measure. While only one albinotic patient showed positive RDE and stereofly results, 86% of normally pigmented nystagmus patients passed the stereofly test, 60% demonstrated 400 sec (Titmus) stereopsis, and 66% showed positive RDE results. These findings reveal that normally pigmented infantile nystagmus patients have variable degrees of stereopsis and no excessive abnormalities of optic nerve fiber decussation as evidenced by flash VECP. Additionally, this study verifies visual pathway abnormalities and the lack of stereopsis in albino nystagmus patients.

Albinism↗

PubMedDate not supplied

Asymmetric horizontal tropias, DVD, and manifest latent nystagmus: an explanation of dissociated horizontal deviation.

Four patients with dissociated horizontal deviation (DHD) are described and an explanation of their horizontal comitant deviations is offered. The patients had asymmetric comitant horizontal deviations dependent on the fixing eye. All of them had unequal visual acuity (VA) and asymmetric manifest latent nystagmus (MLN) documented with eye movement recordings. The subjects appear to use convergence to reduce their nystagmus when viewing with the eye having more severe nystagmus and hence poorer vision. When patients viewed with the eye having less nystagmus, little or no convergence was exhibited. We suggest that DHD may be the manifestation of an asymmetric nystagmus blockage syndrome (NBS). The dampening effect of convergence on nystagmus has been well documented in the past and seems to apply here. The patients demonstrate that a true, but asymmetric NBS, can be found with MLN.

Child↗

PubMedDate not supplied

Surgical correction of excess esotropia at near.

A retrospective study of the surgical treatment of patients with excess esotropia at near was conducted. Thirty-one patients conformed to the following criteria: equal vision in each eye, esotropia at near exceeding distant deviation by 15 or more prism diopters, and no prior surgery. Hyperopes greater than or equal to +1.50 spherical equivalent were measured in their full spectacle correction. All patients had an otherwise normal ocular examination and no overt neurological disease. At distance fixation, approximately half of the population had an esotropia greater than 10 delta and the remainder were orthophoric. All demonstrated a near deviation measuring at least 25 delta. Patient age at time of surgery ranged from 18 months to 36 years. All but two patients underwent bilateral medial rectus recessions of 4.5 mm to 7 mm, based on the near deviation. The remaining two patients underwent right medial rectus recessions of 6 mm each. Minimum postoperative follow-up was 4 months. The majority of patients were able to achieve satisfactory alignment. Many could maintain this alignment without spectacles. Two patients developed consecutive exotropia. One of these patients required bilateral lateral rectus recessions to achieve alignment.

Adolescent↗

PubMedDate not supplied

The role and effectiveness of adjunctive hyperbaric oxygen therapy in the management of musculoskeletal disorders.

The management of musculoskeletal disorders is an increasing challenge to clinicians. Successful treatment relies on a wide range of multidisciplinary interventions. Adjunctive hyperbaric oxygen (HBO) therapy has been used as an orthopaedic treatment for several decades. Positive outcomes have been reported by many authors for orthopaedic infections, wound healing, delayed union and non-union of fractures, acute traumatic ischemia of the extremities, compromised grafts, and burn injuries. Severe side effects have also been reported with this therapy. To aid in the use of HBO therapy in orthopaedics, we reviewed 43 papers published in the past four decades and summarised the mechanisms, effectiveness, indications and contraindications, side effects, and cost impact of adjunctive hyperbaric oxygen therapy in the management of difficult musculoskeletal disorders. Adjunctive HBO therapy is an effective treatment modality for the management of some severe and refractory musculoskeletal problems. If appropriate candidates are carefully identified, hyperbaric oxygen is a limb- and sometimes life-saving therapy. HBO therapy significantly reduces the length of the patient's hospital stay, amputation rate, and wound care expenses. Thus, it is a cost-effective modality. A clinician must understand the side effects and risks of HBO treatment. Close monitoring throughout the treatment is warranted to minimise the risk to the patients.

Clinical Trials as Topic↗

PubMedDate not supplied

The Ilizarov technique in ankle fusion: a preliminary report.

Complex distal tibia fractures and failed ankle arthrodesis represent a significant challenge to today's orthopaedic surgeon. The complexity of these problems is further increased when associated with additional complications such as osteomyelitis, leg length discrepancy or concomitant foot deformity. In many instances, the only viable salvage alternative is amputation. The following is a preliminary report of nineteen cases of complex distal tibia pathology or failed ankle arthrodesis treated with the Ilizarov external fixator apparatus. Of the eighteen cases available for follow-up, fifteen (83.3%) achieved good results with solid ankle arthrodesis and resolution of associated pathology. The Ilizarov may be a viable clinical tool in these difficult cases where amputation is the alternative.

Adolescent↗