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Biomedical subjects

M B Mets

Publications and source records attributed to M B Mets.

At least 37 records · Page 2Linked to original sources
PubMed1995

Postnatal retinal development as measured by the electroretinogram in premature infants.

Light-adapted and dark-adapted electroretinograms were obtained in 27 premature infants who were screened for retinopathy of prematurity shortly after birth. Thirteen showed no retinopathy and 13 had mild to moderate retinopathy, which ranged from stage I, zone III (International Classification) to stage III, zone II. Measurements were made during the first 16 months of life. The configuration of the waveforms under both photopic and scotopic conditions changed during this period showing increased amplitudes of both the a- and the b-waves. A scotopic intensity series was performed and the b-wave amplitudes and implicit times were measured. The b-wave amplitude data were averaged for three adult control subjects, for infants without retinopathy of prematurity measured at 3-4 and at 6-7 months and for infants with retinopathy of prematurity measured at 3-4 and at 6-7 months. The Naka-Rushton function was fitted to the average data. The Rmax increased from 3 to 6 months and from 6 months to adulthood, and the Isat values decreased over this age range. The b-wave implicit times were within normal range in the 6-month data. There was no difference in Rmax or Isat for infants with and without ROP.

Adaptation, Ocular↗
PubMed1995

Bilateral diffuse iris nodular nevi. Clinical and histopathologic characterization.

BACKGROUND: Diffuse nodular nevus of the iris is an uncommon condition that presents with multiple verrucous excrescences distributed diffusely on the iris surface. METHODS: The authors describe 30 patients with bilateral diffuse iris nodular nevi and report associations with bilateral congenital cataract, neurofibromatosis, oculodermal melanocytosis, congenital ptosis, morning glory anomaly, Axenfeld anomaly, or Peters anomaly. RESULTS: Iris nodules were uniform in size and distribution and were brown, as was the surrounding iris. Light and electron microscopy of iridectomy specimens from one patient showed elevated plaques composed of aggregates of plump, lightly pigmented nevoid cells interwoven with mature, densely pigmented spindle-shaped uveal melanocytes. CONCLUSIONS: The authors report the largest clinical series and first ultrastructural description of bilateral diffuse iris nodular nevi, which represents a variant of neural crest development. No ocular complications could be attributed to the iris nodules, which should be differentiated from Lisch nodules and other pathologic iris lesions.

Adolescent↗
PubMed1995

Cochlear implants in young children with Usher's syndrome.

Usher's syndrome (US) is an autosomal recessive disorder characterized by congenital sensorineural hearing loss and retinitis pigmentosa. The majority of affected individuals have severe to profound sensorineural hearing loss and are therefore potential cochlear implant candidates. A goal of our otology program has been early identification and implantation of children with US. At our center, early diagnosis of US has been achieved by comprehensive ophthalmologic evaluation including electroretinography. Four of our 19 pediatric cochlear implant recipients with congenital sensorineural hearing loss were identified with US and implanted prior to the onset of signs or symptoms of visual loss. All children have received measurable benefit from cochlear implantation. In light of the dual sensory deficits present in US, the need for early diagnosis and cochlear implantation is of special importance in this population.

Child↗
PubMed1995

Neurologic and developmental outcome in treated congenital toxoplasmosis.

BACKGROUND: Earlier studies have shown that infants with untreated congenital toxoplasmosis and generalized or neurologic abnormalities at presentation almost uniformly develop mental retardation, seizures, and spasticity. Children with untreated subclinical disease at birth have developed seizures, significant cognitive and motor deficits, and diminution in cognitive function over time. OBJECTIVE: To determine neurologic, cognitive, and motor outcomes for children with congenital toxoplasmosis who were treated for approximately 1 year with pyrimethamine and sulfadiazine. DESIGN AND METHODS: Systematic, prospective, and longitudinal neurologic, cognitive, and motor evaluations were performed for 36 individuals with congenital toxoplasmosis. These infants were born between December 1981 and January 1991 and were treated with pyrimethamine and sulfadiazine for approximately 1 year beginning in the first months of life. Compliance with medications was documented. These individuals were evaluated in a standardized manner in a single center in the first months of life and at approximately 1, 3.5, 5, 7.5, and 10 years of age. Their cognitive function was compared with the cognitive function of a nearest-age, same-sex sibling when such siblings older than 3.5 years were available for study. RESULTS: Signs of active central nervous system infection (eg, cerebrospinal fluid [CSF] pleiocytosis, hypoglycorrhachia, elevated CSF protein, and, in some instances, seizures and motor abnormalities) resolved during therapy. Six of the 36 children had perinatal seizures. Four had their anticonvulsant therapy discontinued successfully within the first months of life, and two additional children developed new seizures at 3 and 5 years of age. Tone and motor abnormalities resolved by 1 year of age in 12 of 20 infants who exhibited abnormalities of tone and motor function at their initial neonatal evaluation. By February 1992, 29 of the 36 children had been evaluated when they were 1 year old, and 23 (79%) had a mean +/- standard deviation Mental Developmental Index (MDI) of 102 +/- 22 (range, 59 to 140). Six (21%) had a measure of their cognitive function that was less than 50. Results of sequential IQ tests, performed at 1.5 year intervals or greater, did not differ significantly over time (P > .05). Seven children with MDIs greater than 50 were compared with sibling controls; they had scores of 87 +/- 11 (range, 68 to 97) and their siblings had scores of 112 +/- 15 (range, 85 to 132) (P = .008). Seventeen of 18 children without hydrocephalus and six of eight children with obstructive hydrocephalus responsive to shunting had normal or near-normal neurologic and developmental outcomes. Children with hydrocephalus ex vacuo present at birth, with high CSF protein, and with lack of response to shunting have done less well. CONCLUSIONS: Neurologic and developmental outcomes were significantly better for most of these treated children than outcomes reported for untreated children or those treated for only 1 month (P < .001). Although the level of cognitive function for treated children was less than for their uninfected siblings (P < .008), there was no significant deterioration in neurologic and cognitive function of the treated children tested sequentially. These favorable treatment outcomes justify systematic identification and treatment of pregnant women with acute gestational Toxoplasma infection and young infants with congenital toxoplasmosis.

Child Development↗
PubMed1994

Ophthalmic disorders in children with Down syndrome.

The goal of this study was to determine the frequency of ophthalmic disorders in a group of young children with Down syndrome who were unselected for ophthalmic abnormalities, and to determine whether examination by a pediatric ophthalmologist should become standard practice. Of 77 children referred to a Down syndrome clinic at a teaching hospital and evaluated by a pediatric ophthalmologist, 61 per cent had ophthalmic disorders needing treatment and monitoring. Furthermore, the percentage of children with ophthalmic disorders increased with age, from 38 per cent in the two- to 12-month-old group to 80 per cent in the five- to 12-year-old group. The authors conclude that children with Down syndrome should be evaluated by a pediatric ophthalmologist in the first six months of life and annually thereafter.

Adolescent↗
PubMed1993

Necrotizing periorbital cellulitis.

We report traumatic necrotizing periorbital cellulitis attributed to group A beta-hemolytic streptococci in a 4-year-old child. The infection was successfully treated via surgical cleansing, drainage, and grafting. The virulence of this organism requires an aggressive approach to the patient with periorbital cellulitis, which is refractory to intravenous antibiotics. Early treatment may limit extensive eyelid necrosis, the resultant secondary deformity, and the need for multiple reconstructive procedures.

Cellulitis↗
PubMed1990

Normal endothelial cell density range in childhood.

Specular microscopy of the in vivo corneal endothelium of 214 clinically normal eyes in children ranging from 5 to 14 years of age showed a regular mosaic of hexagonal cells. The cell population density of individuals presented some variation, as it doses in older subjects. Quantitative analysis permitted us to determine the normal range of the endothelial cell count at each age. The mean (+/- SD) value ranged from 3591 +/- 399 cells per square millimeter at age 5 years to 2697 +/- 246 cells per square millimeter for the oldest subjects. Our data show a rapid decrease in cell density up to age 10 years. We estimate from our data a decrease in cell density of 13% between ages 5 and 7 years and an additional decrease of 12% by age 10 years.

Adolescent↗
PubMed1990

Cataract, hearing loss and hypercholesterolemia.

A new syndrome of congenital cataract, hearing loss, hypercholesterolemia, spasticity of the lower extremities, and perhaps mental retardation, is described. Manifestation in two brothers with no other affected family members suggests an autosomal recessive pattern of inheritance. A discussion of the differential diagnosis of oculo-auditory syndromes is presented.

Cataract↗
PubMed1990

Trisomy 4q with morning glory disc anomaly.

The authors describe a case of trisomy 4q with a unilateral morning glory disc anomaly, a previously unreported ocular manifestation. Previous ocular involvements are summarized.

Child↗
PubMed1989

Human albinos can discriminate spatial frequency and phase as accurately as normal subjects.

Previous experiments testing grating and vernier acuities in albino central vision are consistent with the hypothesis that the deficit in their monocular spatial processing is mainly due to the increased spacing of their foveal cones. This was tested by measuring albino spatial frequency discrimination over the range 0.25-4.0 cpd. The same experiments were performed on three normal subjects both in the fovea and at a peripheral locus at which their grating acuity was identical to that of the albino subjects. Spatial frequency discrimination thresholds averaged 3.71% for albinos, 5.18% for the normal fovea, and 8.81% for the normal periphery, the latter being over 2.3 times greater than albino thresholds. A comparable pattern of results was observed in phase discrimination experiments. These data reject the possibility that albino central vision is similar to normal peripheral vision, but the results are predictable on the hypothesis that the central retina of albinos is a spatially magnified (underdeveloped) version of the normal fovea.

Adult↗
PubMed1988

Ocular findings in partial trisomy 10q syndrome.

We examined three siblings with partial trisomy 10q born to a mother carrying a balanced translocation between chromosomes 4 and 10. Our patients had many of the phenotypic abnormalities characteristic of this syndrome, and their chromosomal abnormality was confirmed by karyotypes of peripheral blood lymphocytes. Two ophthalmoscopic abnormalities not previously reported in this syndrome were noted in our patients. One child had bilateral enlarged, gray optic disks with elevated, blurred margins and distended retinal vessels. Another child had bilateral punctate yellow deposits scattered around the macula and optic disk.

Adolescent↗
PubMed1988

Infantile glaucoma in Down's syndrome (trisomy 21).

We examined five patients with Down's syndrome and bilateral infantile glaucoma. In the first few months of life four patients had large cloudy corneas, breaks in Descemet's membrane, increased intraocular pressure, photophobia, and tearing. In one patient the diagnosis was delayed until 3 1/2 years of age because of concomitant nasolacrimal duct obstruction. Two patients developed cataracts and retinal detachment and have undergone multiple surgical procedures. The clinical course in these two older patients suggests that coexistence of congenital glaucoma, severe myopia, and cataracts in patients with trisomy 21 strongly predisposes for the development of retinal detachment and poor visual outcome.

Adolescent↗
PubMed1988

X-linked congenital stationary night blindness. Review and report of a family with hyperopia.

X-linked congenital stationary night blindness is almost always associated with myopia. We have reviewed all previously reported pedigrees and have found only two with patients without myopia. A recently proposed classification of night blindness includes a complete type associated with myopia and an incomplete type in which both hyperopia and myopia were found. Complete and incomplete types did not occur within the same pedigree. We report on a family in which three of the five affected members had hyperopia and could be classified as the incomplete type and in which a fourth member with myopia was more consistent with the complete type. The lack of myopia in three members of our pedigree can be explained by two hypotheses: crossing over of the night blindness and myopic genes on the X-chromosome, or an autosomal dominant hyperopic gene that masks the myopic gene. The data from our family support the first of these two hypotheses.

Adult↗
PubMed1988

Albino spatial vision as an instance of arrested visual development.

Adult albinos and human infants share a number of common visual characteristics: both have low grating acuity, both lack a foveal pit (foveal hypoplasia), and both have much lower central cone densities than in the normal adult. We have explored the consequences of these characteristics by measuring both spatial and temporal contrast sensitivity in the central retina and by comparing central and peripheral grating and vernier acuities in two young adult albino subjects. To compensate for nystagmus, horizontally oriented patterns were employed. Both subjects had normal flicker sensitivities, but their central grating and vernier acuities were approximately five times worse than normal. At 10.0 degrees in the inferior visual field, however, vernier and grating acuities were normal for both subjects. Finally, the ratio of grating to vernier acuity in albino central vision fell within the normal foveal range, suggesting that albino central vision does not resemble the adult periphery. These results are consistent with the hypothesis that spatial processing deficiencies in albino central vision are a direct consequence of the increased spacing of their central cones. Our data are comparable to available psychophysical results obtained from infants of approx. 10 months of age, thus suggesting that the albino visual system may represent a case of arrested development.

Adult↗
PubMed1988

Spatial frequency and orientation tuning of spatial visual mechanisms in human albinos.

A masking paradigm was used to measure the spatial frequency and orientation tuning of spatial mechanisms in the albino visual system. Threshold elevation curves obtained in this manner at test spatial frequencies of 0.25 cycles/deg (cpd), 0.50 cpd, and 1 cpd have the same shape as curves obtained from normal subjects at test frequencies two octaves higher. Additional masking studies showed that contrast processing in albinos obeys the same compressive power law as in normals. Thus, spatial mechanisms in albino central vision have normal spatial frequency and orientation bandwidths. As central cones in the albino are spaced 3-4 times further apart than in the normal fovea, these results support the hypothesis that monocular spatial vision in albinos is primarily limited by this increased receptor spacing. It is hypothesized that this, in turn, is the result of arrested development of the albino retina.

Adult↗
PubMed1987

Leber's congenital amaurosis. Retrospective review of 43 cases and a new fundus finding in two cases.

Leber's congenital amaurosis is a hereditary clinical disorder that may be associated with several different diseases. This study consists of a retrospective review of 43 cases. Twenty of our patients had fundus appearances that resembled retinitis pigmentosa. Five had normal-appearing fundi. The remainder had other, previously reported fundus abnormalities, with the exception of two patients who demonstrated a new fundus finding, a nummular pigmentary pattern. Other associated eye anomalies included cataracts, keratoconus, ptosis, and strabismus. The most frequent systemic associations were mental retardation, cystic renal disease, skeletal disorders, and hydrocephalus.

Abnormalities, Multiple↗