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Biomedical subjects

M X Repka

Publications and source records attributed to M X Repka.

At least 55 records · Page 3Linked to original sources
PubMed1992

Calf lung surfactant extract prophylaxis and retinopathy of prematurity.

Retinopathy of prematurity (ROP) is an important cause of blindness among extremely low birth weight infants (birth weight less than or equal to 1000 g). In the 1990s, greater numbers of extremely low birth weight infants will survive, in part due to routine surfactant replacement therapy for neonatal respiratory distress syndrome. Few studies have evaluated the effect of surfactant therapy on the incidence and severity of ROP. The authors performed a review of the records of extremely low birth weight infants born in two 2-year intervals before and after initiation of a clinical protocol in which all extremely low birth weight infants received prophylactic treatment with calf lung surfactant extract (Infasurf). Surfactant therapy was associated with a significant improvement in survival to discharge (79% [88 of 112] versus 63% [82 of 131]; P = 0.01). Compared with control infants, surfactant-treated infants had a significantly lower incidence of any stage of ROP (64% [56 of 87] versus 85% [68 of 80]; P less than 0.004). The incidence of threshold (Stage 3 plus or greater) ROP was substantially reduced (3.4% [3 of 87] versus 10% [8 of 80]; P = 0.16)). The surfactant-associated reduction in ROP was independent of birth weight, gestational age, race, or sex. These data suggest that Infasurf may substantially reduce the incidence and severity of ROP in the extremely low birth weight population.

Bronchopulmonary Dysplasia↗
PubMed1992

Development of myopia in infants with birth weights less than 1251 grams. The Cryotherapy for Retinopathy of Prematurity Cooperative Group.

The authors report on the incidence of myopia in a large group of premature infants with birth weights of less than 1251 g followed as part of the multicenter study of Cryotherapy for Retinopathy of Prematurity. None of the eyes reported here underwent cryotherapy. Eyes were refracted using cycloplegic retinoscopy at 3 months (n = 2916), 12 months (n = 2626), and 24 months (n = 961 at 5 of the 23 centers) after term. Myopia was observed in approximately 20% of the children at each test age. The percentage of high myopia (greater than or equal to 5 diopters) doubled from 2% to 4.6% between 3 and 12 months and remained stable thereafter. Lower birth weight and increasing severity of retinopathy of prematurity (ROP) were strong predictors of myopia and high myopia. In addition, anisometropia, astigmatism, and the presence of posterior pole residua from ROP also were associated with a higher incidence of myopia and high myopia.

Anisometropia↗
PubMed1991

A primate model of macular cyst.

Perfluoropropane (C3F8) was injected into nine eyes of six cynomolgus monkeys. In all nine eyes, macular changes consistent with the development of a macular cyst were noted within 3 months after injection. On fluorescein angiography, there was no evidence of retinal vascular leakage associated with the macular cysts. Histopathologic evaluation of six eyes demonstrated microcystic changes throughout the perifoveal inner nuclear layer. These coalesced into larger cystic spaces in the outer plexiform layer of the central macula. These macular changes are previously unreported in patients or monkeys undergoing intravitreal injection of expansile gases. This model for macular cysts may be helpful in evaluating the pathogenesis and role of interventional strategies in patients with cystoid macular edema.

Animals↗
PubMed1991

Gestational age assessment in preterm neonates weighing less than 1500 grams.

Postnatal assessment of gestational age in preterm neonates traditionally has been performed using the methods of Dubowitz and Ballard. This study was designed to determine the accuracy of these methods in a sample of very low birth weight preterm neonates. Dubowitz and Ballard examinations were done on 110 preterm neonates within the first 72 hours of life by a neonatologist masked to the gestational age assessed antenatally. Mean birth weight was 1066 +/- 256 g (SD). These data were compared with gestational age assessments using last menstrual period and best obstetric estimate calculated by an obstetrician unaware of the neonatal examination. Mean gestational age using last menstrual period was 28.3 +/- 2.9 weeks. Mean differences between last menstrual period and Dubowitz/Ballard were -2.8 +/- 2.1 weeks and -2.6 +/- 2.2 weeks, respectively. Results using best obstetric estimate were similar. An ophthalmologist examined lens vessels of 89 neonates. A similar pattern toward overestimation of gestational age interval by Dubowitz/Ballard was seen at each lens vessel grade. The Dubowitz and Ballard examinations are inaccurate methods of assessing gestational age in preterm neonates with birth weights less than 1500 g.

Birth Weight↗
PubMed1991

Early visual deprivation results in persistent strabismus and nystagmus in monkeys.

To understand to what extent visual-pattern deprivation during infancy results in strabismus and nystagmus, the authors examined the long-term consequences of this type of deprivation in monkeys during the first 50 days of life. Three cynomolgus and three rhesus monkeys had the eyelids sutured closed within 24 hr of birth. At 25 days of age, the eyelids were opened, and the eyelids of the fellow eye were sutured closed for an additional 25 days (reverse-eyelid suture). When the eyelids were opened at 50 days of age, each monkey was found to have 20-30 delta of exotropia and nystagmus, which persisted for the duration of the study (1 yr). The cynomolgus monkeys developed a monocular 8-10 Hz pendular nystagmus in the eye sutured first. The rhesus monkeys developed a conjugate nystagmus with both jerk and pendular components. The slow phases often had velocity-increasing profiles. The rhesus monkeys also had a superimposed latent component to the nystagmus found during monocular viewing. One additional rhesus monkey was examined after 55 days of binocular-eyelid suturing. This monkey also developed exotropia and nystagmus resembling that of the other rhesus monkeys. These findings suggest that early pattern vision in monkeys is necessary for the development of normal ocular alignment and gaze-holding ability.

Animals↗
PubMed1990

A primate model of anterior segment ischemia after strabismus surgery. The role of the conjunctival circulation.

Fornix conjunctival incisions in strabismus surgery may provide partial protection against anterior segment ischemia by preserving the perilimbal conjunctival-Tenon's circulation, which is disrupted with limbal conjunctival incisions. Six adult cynomolgus monkeys underwent tenotomies of three or four rectus muscles by making limbal conjunctival incisions in one eye and fornix incisions in the other. Iris fluorescein angiography and slit-lamp biomicroscopy were used to monitor changes. The eyes that had limbal incisions exhibited more severe anterior segment ischemic changes than the eyes that had fornix incisions in every instance of four rectus muscle surgery.

Animals↗
PubMed1989

Divisional oculomotor nerve paresis caused by intrinsic brainstem disease.

Two patients with findings ascribable to superior branch oculomotor nerve paresis and one patient with findings ascribable to an inferior branch paresis are described. In each patient the paresis was caused by an intra-axial midbrain lesion. These patients represent the first described cases of divisional oculomotor nerve paresis caused by intrinsic brainstem disease.

Adult↗
PubMed1989

Visual outcome after surgical removal of craniopharyngiomas.

Thirty patients with craniopharyngiomas were examined preoperatively and immediately postoperatively to determine their level of visual impairment and the extent of visual recovery. Twenty-two patients also were examined during extended follow-up. Twelve of these patients were younger than 18 years of age and 18 were older than 18 years of age at the time of diagnosis. Visual acuity was reduced in 42% of eyes preoperatively. One week postoperatively, visual acuity was reduced in only 23% of eyes. Color vision was a more sensitive indicator of afferent system damage, being abnormal at presentation in 71% of patients. Visual field defects were typically bitemporal hemianopsias, but 20% of patients with evidence of optic neuropathy had no definite visual field deficit preoperatively. Postoperatively, 48% of patients had normal visual fields. There was no long-term improvement in visual acuity or field performance for patients with deficits present after the first postoperative month during an average 2.8 years of follow-up.

Adolescent↗
PubMed1989

The effect of age on normal human optic nerve fiber number and diameter.

In one optic nerve from each of 19 persons, the authors determined the number of axons, the distribution of fiber diameter, and the total neural area. The mean fiber count was 693,316, the mean neural area was 5.17 mm2, and the mean axonal fiber diameter was 0.96 microns. No significant decline in fiber number or neural area with increasing age was found. The authors found a large variability of axonal number among their patients. This variability would have obscured any small effect of aging. Linear regression analysis of the effect of age on mean axonal diameter yielded a slight negative slope (P less than 0.01), suggesting a redistribution of fiber diameter. This could occur from axonal shrinkage, from preferential large fiber loss, or from the technical features of tissue acquisition and analysis. The authors suspect that the explanation is a selective loss of large nerve fibers.

Adolescent↗
PubMed1988

Optic atrophy in children.

We reviewed the records of 218 children in whom a diagnosis of optic atrophy had been made between 1978 and 1987. A cause for the atrophy was determined for 195 patients (89%). Tumor, the most frequent cause, was found in 63 patients (29%). The most common tumor was a glioma of the anterior visual pathway; it was found in 27 patients (43% of tumors; 12% overall). The second most frequently encountered tumor, a craniopharyngioma, was found in 14 patients. Inflammation, the second most common cause of optic atrophy, occurred in 38 children (17%). Trauma caused optic atrophy in 24 patients (11%). No cause could be found for 23 patients (11%). Thirteen patients were less than 1 year of age at the time of diagnosis. Three of these patients had tumors. One was a cerebral glioblastoma, and the other two were optic gliomas. The diagnosis of optic atrophy in infancy does not imply a benign cause.

Adolescent↗
PubMed1988

Comparison of hang-back medial rectus recession with conventional recession.

Hang-back recession is commonly used for adjustable strabismus surgery and surgery for dissociated vertical deviation. The authors have begun to use the hand-back technique for routine recessions as well, to simplify the procedure and to lessen the risk of scleral perforation. In 49 consecutive children undergoing conventional bilateral medial rectus recession and 31 consecutive children undergoing hang-back recession, the success rate (+/- 10 prism diopters [PD]) was 80% in the conventional group and 74% in the hang-back group at 6 weeks. The dose-response curves were nearly identical. These results confirm that hang-back recessions for infantile and acquired esotropia are a predictable alternative to conventional strabismus surgery.

Child↗
PubMed1988

The Wilmer Information System. A classification and retrieval system for information on diagnosis and therapy in ophthalmology.

The Wilmer Information System is a computerized medical information system used for the storage and retrieval of data pertaining to patient demographics, diagnosis, and therapy. The heart of the system is an expandable, hierarchical code based on International Classification of Diseases, 9th Revision (ICD-9) diagnosis codes and Physicians' Current Procedural Terminology procedure codes. Customized coding sheets containing highly specific diagnosis and procedure codes have been designed for each subspecialty area in ophthalmology. Interactive database management software facilitates data entry and retrieval. The system can be used to search for patients who meet very specific criteria, or to produce cumulative visit reports and summary statistics.

Computers↗
PubMed1986

Depth distortion during slitlamp biomicroscopy of the fundus.

The apparent depth of an optic nerve cup or apparent height of a fundus lesion changes with the optics used by an examiner. With slit-lamp biomicroscopy of the fundus, both the auxiliary fundus lens and the biomicroscope contribute to differences in magnification that produces distortion of the object. It is important to understand these differences so that inaccurate conclusions are not drawn and inappropriate therapy will not be instituted when the examiner uses different instruments for making serial observations or uses an unfamiliar instrument.

Depth Perception↗
PubMed1985

Determination of optical penalization by vectographic fixation reversal.

Optical penalization for distance is a useful alternative to occlusion for treating amblyopia, and as maintenance therapy following occlusion. It is particularly useful in cases of patching noncompliance. The major key to patient acceptance is choosing the minimal amount of penalization necessary, while still ensuring that the patient actually switches fixation to the amblyopic eye. We have found the vectographic letter slide reliable for identifying the fixing eye for distance vision. Thirty-four patients were treated for anisometropic or strabismic amblyopia with distance optical penalization without the use of cycloplegic agents. Twenty-two patients had improvement of their visual acuity, and 10 patients remained the same during an average follow-up period of 22.5 months. The average visual acuity improved from 20/40 to 20/32. The dominant eye required an average of only +1.25 diopters of fogging for the patient to switch fixation to the amblyopic eye, significantly less than the arbitrary +3.00 diopters advocated by some clinicians.

Amblyopia↗
PubMed1984

Pseudotumor cerebri.

Two young women with idiopathic pseudotumor cerebri were treated successfully with lumboperitoneal shunts. Their shunts were removed electively several years later, following which there was rapid increase of cerebrospinal fluid pressure. In one patient, rapid increase of intracranial pressure resulted in bilateral visual loss. These cases provide further evidence that idiopathic pseudotumor cerebri may not be a self-limited condition.

Adult↗
PubMed1984

Optic disc structure in anterior ischemic optic neuropathy.

The etiology of anterior ischemic optic neuropathy (AION), when not associated with giant cell arteritis, is usually unknown. Clinical, pathologic, and experimental studies have not determined a cause. The optic disc appearance in both the involved and normal fellow eye was studied in 51 patients with acute nonarteritic AION. The number of discs (both involved and fellow) without a physiologic cup was significantly greater than would be expected from normal population studies. The etiology of nonarteritic AION may be related to the anatomic configuration of the optic nerve.

Eye↗
PubMed1984

Optic neuropathy from the use of intracranial muslin.

Following repair of an anterior communicating artery aneurysm with McFadden clips and muslin, a 32-year-old woman developed a steroid-responsive optic neuropathy. When she was explored, a sterile abscess with surrounding fibrotic tissue involving the muslin was found adjacent to the right optic nerve. The patient's vision improved following removal of the abscess.

Abscess↗