Biomedical subjects

M X Repka

Publications and source records attributed to M X Repka.

76 records · Page 5Linked to original sources

PubMedDate not supplied

The adjustable globe: a technique for adjustable strabismus surgery.

BACKGROUND: Conventional adjustable strabismus surgery involves postoperative repositioning of individual muscles anchored to the sclera via adjustable sutures. Greaves has described anchoring opposing rectus muscles to one another, via sutures passing on either side of the limbus. With the muscles disinserted, the "freed" globe can be adjusted to the desired position within the resulting suture cradle. Friction of the sutures against the sclera holds the muscles in place until healing occurs. METHODS: Using a cul-de-sac approach, we performed 23 horizontal and three vertical adjustable globe procedures, with median follow-up of 7 weeks. Four procedures were performed on nonhuman primates, monitored with iris fluorescein angiography. RESULTS: Esodeviations were well corrected, but exodeviations were often grossly undercorrected. Prolonged postoperative discomfort and photophobia were experienced. Possible evidence for mild anterior segment ischemia was noted. CONCLUSION: Concern about poor results with exodeviations, discomfort, and possible anterior segment ischemia led us to abandon this procedure.

Adolescent↗

PubMedDate not supplied

Automated analysis of electromyographic (EMG) recordings during botulinum injections.

PURPOSE: Botulinum toxin is injected into extraocular muscles using electromyographic (EMG) guidance to confirm needle location prior to injection. The purpose of this study was to develop and test an automated, objective method of storing and grading EMG signal quality obtained during botulinum injection. A reliable, nonsubjective estimate of signal quality will enhance future studies of the complications or effectiveness of botulinum toxin injections into extraocular muscle. METHODS: Injections were administered using a standard procedure. The EMG was digitized, recorded, and analyzed using discrete Fourier transform and power spectrum analysis. Audible signal quality was also graded subjectively by the surgeon. Patients were followed to determine the clinical response to the injection. RESULTS: Eighteen patients (24 injections) were studied. Each sample was collected and analyzed in less than one second. The EMG contained signals over a range of frequencies from 50 to 500 Hz, with an average peak near 90 Hz. Substantial variability of the signal was observed between patients. Contracting muscle had a higher total power and peak frequency in most, but not all, cases. Total signal power correlated moderately with subjective estimates of signal quality. Neither subjective nor computer-derived signal quality estimates correlated with the response to injection or complications. CONCLUSIONS: Computerized signal analysis can automatically characterize EMG signal power and frequency distribution. Although this technique has the potential to identify needle location at the time of botulinum injection accurately, signal variability limited the clinical and research utility of the present protocol.

Botulinum Toxins↗

PubMedDate not supplied

Randomized comparison of diode laser photocoagulation versus cryotherapy for threshold retinopathy of prematurity: 3-year outcome.

PURPOSE: To report the structural and functional outcomes at a minimum of 3 years postmenstrual corrected age following laser- or cryoablation of threshold retinopathy of prematurity (ROP). METHODS: Nineteen patients were entered into a prospective, randomized treatment protocol, in which one eye received cryotherapy and the other received diode laser photocoagulation. Asymmetric eyes were randomly assigned. Two patients have died and five were not available for 3-year outcome exams. RESULTS: Seven males and five females with a mean birthweight of 638 g and a mean gestational age of 24.9 weeks were examined. Two patients had asymmetrical disease and received laser photocoagulation. Two discordant structural outcomes were present among the 10 symmetrical cases. The laser-treated eyes had the favorable outcome; the cryotherapy-treated eyes had the unfavorable outcome. The geometric mean visual acuity after laser photocoagulation was 20/52; after cryotherapy, it was 20/91 (P = 0.046). The mean refractive error was -6.60 diopters (D) after laser photocoagulation and -7.62 D after cryotherapy. Seven patients (58%) have developed strabismus. CONCLUSIONS: Laser photocoagulation appears to have an outcome at least comparable to cryotherapy when the patients are examined 3 years following therapy. These data, including visual acuity and refractive error, suggest that laser photocoagulation may have a minimal advantage over cryotherapy in the treatment of ROP.

Child, Preschool↗

PubMedDate not supplied

Visual outcome of craniopharyngioma in children.

PURPOSE: To assess the visual outcome of children with craniopharyngioma and identify predictors of visual loss. METHODS: A retrospective analysis of all patients younger than 18 at presentation who were evaluated between 1984 and 1995 was performed. Visual outcome was assessed as a function of age, systemic symptoms, visual acuity at presentation, and need for postoperative radiotherapy. RESULTS: Thirty-one patients were identified, with a mean age of 7.7 years (range, 1.2 to 16.8 years) at the time of surgical resection. The initial visual acuity (known in 20 patients at presentation) in the better-seeing eye was > or = 20/40 in 14 (70%) patients and < 20/200 in 2 (10%) patients. Twelve (39%) patients presented with visual symptoms and 15 (48%) with systemic symptoms. All patients underwent surgical resection; some patients required multiple surgeries (52%) or adjuvant radiotherapy (48%). The mean postsurgical follow up was 6.5 years (range, 4 days to 25 years). Postoperative visual acuity was > or = 20/40 in the better eye in 22 (71%) patients; 8 (26%) patients had visual acuity < 20/200 in their better-seeing eye. Optic atrophy developed in 51 eyes of 27 patients (81%). CONCLUSIONS: Craniopharyngioma presents with visual symptoms in children and is associated with significant permanent visual dysfunction. Age younger than 6 years at presentation and visual symptoms at presentation were associated with a significantly poorer visual outcome. Craniopharyngioma should be considered in the differential diagnosis of every child with amblyopia, particularly when no amblyogenic factors such as anisometropia or strabismus are present.

Adolescent↗