Biomedical subjects
M M Parks
Publications and source records attributed to M M Parks.
Fornix incision for horizontal rectus muscle surgery.
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Symposium: infantile esotropia. Summary and conclusions.
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Management of infantile cataracts.
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Early surgery for congenital esotropia.
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Treatment of eccentric fixation in children under four years of age.
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Brown's syndrome.
Brown's syndrome is a well-recognized clinical disorder of ocular motility manifesting most notably a restriction of active and passive elevation in adduction. The original name, "superior oblique tendon sheath syndrome," is no longer appropriate, since it has been shown that the tissue surrounding the anterior superior oblique tendon is blameless as a restrictive force. "True" and "simulated" as descriptive modifiers should also be discarded, as they relate to the disproven sheath concept. Brown's syndrome occurs as a congenital or acquired, constant or intermittent condition; the common link is restriction of free movement through the trochlea pulley mechanism. The various etiologic theories are reviewed and the spectrum of medical and surgical treatments are described and evaluated. Evidence suggests that subtypes of Brown's syndrome lie on a single continuum and that spontaneous resolution occurs in each group, probably more often than previously recognized. A simplified classification scheme is encouraged and possible future directions in Brown's syndrome research are introduced.
Pediatric ophthalmology and I.
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The etiology, treatment and prevention of the "slipped muscle".
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The effect of superior oblique weakening procedures on primary position horizontal alignment.
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Safety evaluation of BSS plus in pediatric intraocular surgery.
An open-label study was conducted to determine the safety of a new intraocular irrigating solution, BSS Plus, when used during pediatric ophthalmic surgery. BBS Plus is a modified glutathione-bicarbonate-Ringer's solution which contains the necessary ions, buffers, and substrates for maintenance of normal cellular metabolism, function, and structural integrity when used as a perfusate during ophthalmic surgical procedures. At three centers, 30 patients undergoing lens aspiration or anterior segment reconstruction using vitrectomy instrumentation were enrolled in this study. Transient postoperative increases in intracellular pressure and internal or external ocular inflammatory signs were seen which were consistent with the trauma produced by the surgical procedure. The solution was judged to be safe when used in these surgical indications.
Management of the posterior capsule in congenital cataracts.
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Practical management of amblyopia.
One hundred sixteen strabismus patients with amblyopia treated with initial full-time or part-time conventional occlusion of the preferred eye followed when necessary with maintenance occlusion up to a maximum of nine years were studied. Based on the need for maintenance occlusion, patients were divided into a primary occlusion group, composed of patients who did not require maintenance occlusion and a maintenance group occlusion group, composed of patients who did require maintenance occlusion. The main difference between the two groups of patients was the degree of amblyopia at the onset of occlusion therapy, being significantly greater in the maintenance occlusion group. The maintenance occlusion group showed a significantly higher incidence of visual acuity regression when evaluated at ages 12 and 13 years. Occlusion therapy administered to strabismus patients in the manner described in this study resulted in significant visual improvement with a regression in visual acuity of no more than an average of one line on the Snellen chart.
Kestenbaum surgical procedure for torticollis secondary to congenital nystagmus.
The records of 48 patients with congenital nystagmus who required surgery for a significant head turn were reviewed to compare the effectiveness of the surgical techniques. Patients were omitted from the study if the last postoperative visit was less than five months following surgery, or if the surgery was for a vertical head posture. The average preoperative head turn of the 38 patients with horizontal nystagmus was 41.3 degrees with an average postoperative head turn of 11.5 degrees. The net change in head turn was 33.4 degrees. The average duration of time from surgery to final examination was four years and six months. The study was divided into six groups of patients. The first group received the Parks modification of the standard Kestenbaum procedure, the 5-6-7-8 millimeter procedure. The second group received the above procedure plus 1 mm additional surgery. The third group received another modification by Parks of 6.5-8-9-10 millimeters. The fourth group received the Calhoun and Harley modification of 40% augmentation of the original Parks recommendation, and the fifth group received 60% modification. The sixth group required more than one procedure on the horizontal recti for the abnormal head posture. The pre- and postoperative measurements are compared for each of these six groups. In some patients followed for many years, there is a tendency for a gradual return toward the preoperative head posture. In four patients in the study, the gaze preference was shifted to the opposite direction postoperatively.
Severe visual loss resulting from occlusion therapy for amblyopia.
Two children developed profound visual loss in the eye being patched full time because of strabismic amblyopia in the fellow eye. The first had been patched for 13 days at age 18 months. Complete resolution was noted on the 40th day of reverse occlusion. The second had been patched for 1 month at age 9 months. After 3 months without treatment, reverse occlusion was instituted and was continued for 3 years. Mild amblyopia persists in both eyes of the second child. Although rare, occlusion amblyopia can occur in young children being patched full time. We usually avoid full-time occlusion and monitor patients at intervals at least as frequent as 1 week per year of age.
Rate of deterioration in accommodative esotropia correlated to the AC/A relationship.
We analyzed the claim that accommodative esotropia tends to deteriorate with greater frequency if the accommodation convergence relationship (AC/A) is high. Records of 119 patients whose eyes were aligned with spectacles alone were studied. Their AC/A relationships were graded according to the difference between the distance and near measurements: normal included 0 to 9 prism diopters (delta) difference; grade 1 ranged from 10 to 19 delta difference; grade 2 from 20 to 29 delta difference; and in grade 3 the difference was 30 delta or greater. Deterioration is characterized by a nonaccommodative component of esotropia greater than 10 delta at distance becoming superimposed on the initial accommodative esotropia. Deterioration occurred in 7.7% of patients with a normal AC/A, 25% with grade 1 high AC/A, 44% with grade 2 high AC/A, and 52% with grade 3 high AC/A. Hypotheses were investigated using chi square, t-test, analysis of variance (ANOVA), and log linear analyses. Distributional differences were highly significant by chi square test (p = 0.001) with a rejection of the null hypothesis of no difference between the groups at the alpha = 0.05 level. An alternate analysis of average AC/A ratio in the deteriorated versus nondeteriorated patients was equally statistically significant by the t-test. Hypermetropia was significantly higher in the normal AC/A group. Multi-factor comparisons showed that time-to-deterioration, treatment delay, age of onset, and amblyopia were factors that did not relate significantly to the incidence of deterioration.
Accommodation deficiency in healthy young individuals.
Ten patients, ages 10 to 19, with accommodation insufficiency are reported. All patients were in good health and asymptomatic, except for asthenopia during near visual activities. Each patient's amplitude of accommodation was measured and found to be considerably below the minimal normal for their respective ages (an average of 6 diopters). Only three patients had associated convergence insufficiency. No etiology for the diminished accommodation was suggested by history or could be identified by careful examination. All patients were successfully managed optically with bifocals or reading glasses, although three required the addition of base-in prisms for the near exodeviation. Near vision testing and determination of the near point of accommodation should be part of the pediatric ophthalmologic examination in all patients with complaints referable to their reading and visual performance at near.
Acquired monofixation syndrome.
Monofixation syndrome is a well documented sensory abnormality occurring in patients with childhood-onset strabismus. We report the development of monofixation syndrome in six adults with strabismus. It is proposed that constant strabismus, which precludes and prevents bifixation, can result in the development of monofixation syndrome if the strabismic deviation is not corrected promptly.