Biomedical subjects

E Birch

Publications and source records attributed to E Birch.

10 recordsLinked to original sources

PubMed2001

The role of anisometropia in the development of accommodative esotropia.

PURPOSE: To determine whether anisometropia increases the risk for the development of accommodative esotropia with hypermetropia. METHODS: Records of all new patients with a refractive error of +2.00 D or more (mean spherical equivalent of both eyes) over a 42-month period were reviewed. Three hundred forty-five patients were thus analyzed to determine the effect of anisometropia (>or=1 D) on the relative risk of developing accommodative esotropia and of developing unsatisfactory control with spectacles once esotropia was present. RESULTS: Anisometropia (>or=1 D) increased the relative risk of developing accommodative esotropia to 1.68 (P < .05). Anisometropia (>or=1 D) increased the relative risk for esotropia to 7.8 (P < .05) in patients with a mean spherical equivalent less than +3.00 D and increased it to 1.49 (P < .05) in patients with a mean spherical equivalent of +3.00 D or more (P = .016). In patients with esotropia and anisometropia (>or=1 D), the relative risk for a deviation that was unsatisfactorily controlled with spectacles was 1.72 (P < .05) compared with patients with esotropia but without anisometropia. Unsatisfactorily controlled esotropia was present in 33% of patients with anisometropia versus 0% of patients without anisometropia, with a mean hypermetropic spherical equivalent of less than +3.00 D (P = .003); however, anisometropia did not significantly increase the relative risk of unsatisfactory control of esotropia with spectacles in patients with a hypermetropic spherical equivalent of +3.00 D or more. Although amblyopia and anisometropia were closely associated, anisometropia increased the relative risk for esotropia to 2.14 (P < .05), even in the absence of amblyopia. CONCLUSIONS: Anisometropia (>or=1 D) is a significant risk factor for the development of accommodative esotropia, especially in patients with lower overall hypermetropia (>+3.00 D). Anisometropia also increases the risk that an accommodative esotropia will not be satisfactorily aligned with spectacles.

Accommodation, Ocular↗

PubMed2000

The role of anisometropia in the development of accommodative esotropia.

PURPOSE: To determine if anisometropia increases the risk for the development of accommodative esotropia in hypermetropia. METHODS: Records of all new patients with a refractive error of > or = +2.00 (mean spherical equivalent [SE] of both eyes) over a 42-month period were reviewed. Three hundred forty-five (345) patients were thus analyzed to determine the effect of anisometropia (> or = 1 diopter [D]) on the relative risk of developing esodeviation and of requiring surgical correction once esodeviation was present (uncontrolled deviation). RESULTS: Anisometropia (> or = 1 D) increased the relative risk of developing accommodative esodeviation to 1.68 (P < .05). Anisometropia (> or = 1 D) increased the relative risk for esodeviation to 7.8 (P < .05) in patients with a mean SE of < 3 D and to 1.49 (P < .05) in patients with SE of > or = 3 D. This difference was significant (P = .016). In patients with esotropia and anisometropia (> or = 1 D), the relative risk for an uncontrolled deviation was 1.72 (P < .05) compared with nonanisometropic esotropic patients. Uncontrolled esodeviation was present in 33% of anisometropic patients versus 0% of nonanisometropic patients with a mean hypermetropic SE of < 3 D (P = .003); however, anisometropia did not increase the relative risk of uncontrolled esotropia in patients with SE of > or = 3 D. Although amblyopia and anisometropia were closely associated, anisometropia increased the relative risk of esodeviation to 2.14 (P < .05) even in the absence of amblyopia. CONCLUSIONS: Anisometropia (> 1 D) is a significant risk factor for the development of accommodative esodeviation, especially in patients with lower overall hypermetropia (< 3 D). Anisometropia also increases the risk that an accommodative esodeviation will not be fully eliminated with hypermetropic correction.

Accommodation, Ocular↗

PubMed1998

The natural history of infantile esotropia during the first six months of life. Pediatric Eye Disease Investigator Group.

PURPOSE: The present study addresses the natural history ocular alignment in infantile esotropia that presents at 2 to 4 months of age. METHODS: Eye alignment during the first 6 months of life was evaluated in two cohorts of healthy infants who initially had esotropia at 2 to 4 months of age; 80 infants were enrolled in a prospective study at the Retina Foundation of the Southwest (RFSW), and 41 infants were reviewed retrospectively as a pilot study for the Early Surgery for Congenital Esotropia (ESCET) multicenter trial. In addition, 79 of the 80 children in the RFSW cohort were reexamined at 4.5 years of age or older for ocular alignment and stereopsis. RESULTS: Among infants who initially had constant esotropia > or = 40 PD, 0 of 45 children in the RFSW cohort and 0 of 21 children in the ESCET cohort showed resolution to orthophoria. In addition, only 2 infants showed a reduction in angle of deviation below 40 PD (one to 35 PD and one to 20 PD). Resolution to orthophoria was noted in a few infants who initially had small angle or variable angle esotropia. On follow-up at 4.5 years of age or greater, 91% of the children in the RFSW cohort had alignment within 8 PD of orthoposition and 30% had stereoacuity of 3000" to 60". Children who underwent surgical alignment at 6 months of age had a higher prevalence of coarse stereopsis than children who underwent alignment at 7 to 15 months of age. CONCLUSIONS: Taken together, these results suggest that infants who present at 2 to 4 months of age with constant esotropia of 40 PD or greater are valid candidates for surgical treatment. In addition, data from long-term follow-up support the hypothesis that early surgical alignment may promote the development of at least coarse stereopsis in these infants.

Depth Perception↗

PubMed1996

Role of essential fatty acids in the function of the developing nervous system.

The basis for n-3 fatty acid essentially in humans includes not only biochemical evidence but functional measures associated with n-3 deficiency in human and nonhuman primates. Functional development of the retina and the occipital cortex are affected by alpha-linolenic acid deficiency and by a lack of docosahexaenoic acid (DHA) in preterm infant formulas and, as reported more recently, in term diets. Functional effects of n-3 supply on sleep-wake cycles and heart rate rhythms support the need for dietary n-3 fatty acids during early development. Our results indicate that n-3 long-chain polyunsaturated fatty acids should be considered provisionally essential for infant nutrition. DHA may also be required by individuals with inherited metabolic defects in elongation and desaturation activity, such as patients with peroxisomal disorders and some forms of retinitis pigmentosa.

Animals↗

PubMed1996

FPL and VEP measures of fusion, stereopsis and stereoacuity in normal infants.

Dynamic random dot fusion, stereopsis and stereoacuity were evaluated in 149 healthy, fullterm infants, using both forced-choice preferential looking (FPL) and steady-state visual evoked potential (VEP) protocols. Few infants aged 2-3 months demonstrated fusion or stereopsis in either the FPL or VEP protocol; most infants aged 5 months and older demonstrated fusion and stereopsis in both protocols. Both FLP and VEP stereoacuity approached adult-level (< 60 sec) by 6-7 months of age. Both infants and adults exhibited non-monotonic VEP amplitude vs disparity functions with a step change in phase at an intermediate disparity, consistent with separate fine and coarse disparity mechanisms.

Aging↗

PubMed1992

Visual and brain function measurements in studies of n-3 fatty acid requirements of infants.

Dietary n-6 or n-3 fatty acid deficiencies result in changes in brain and retinal phospholipid composition that can affect cell membrane and organ function. An n-3 fatty acid deficiency has been associated with altered electroretinograms and reduced visual acuity in animals. Other promising methods for assessing the effects of fatty acid deficiencies on brain and retinal maturation include visual-evoked potential acuity, sleep-wake cycle, auditory brain stem-evoked response, somatosensory-evoked potential measurements, and the Fagan and forced-choice preferential looking acuity tests. Preterm infants fed a formula low in alpha-linolenic acid (18:3n-3) had significant electroretinographic changes at discharge from the nursery, indicating a delay in rod photoreceptor maturation. However, infants fed human milk or supplementary n-3 fatty acids as marine oil had electroretinogram indexes like those of infants of comparable age tested soon after birth. Visual cortex function, measured by pattern reversal visual-evoked potential and forced-choice preferential looking visual acuity response, was also better in infants fed human milk or marine oil-supplemented formula than in infants fed formulas without docosahexaenoic acid (22:6n-3). Studies of term infants suggest that visual acuity is more mature in breast-fed than in formula-fed infants [corrected] at 4 months and 3 years of age.

Brain↗

PubMed1980

Stereoacuity of human infants.

Stereograms were presented in a two-choice preference procedure. The mean age at which stereopsis was first demonstrable was 16 weeks. By a mean age of 21 weeks, infants had achieved stereoacuity of 1 minute of arc or better. In comparison with the relatively slow development of visual acuity, the time course for the development of stereoacuity is extremely rapid.

Age Factors↗

PubMedDate not supplied

Operant acuity of toddlers and developmentally delayed children with low vision.

The present report describes an operant procedure for the assessment of grating acuity in young and/or developmentally delayed children. Prior to testing, the child was trained to point to a grating presented on one of two equally bright screens. A reward was given to the child for each correct response. During the test, the gratings became progressively finer until the child no longer made consistently correct choices. Normative data from 90 children show improvement in grating acuity during years one to five (from 20/50 to 20/17). Results were also obtained from 100 consecutive pediatric patients who were thought to be visually unresponsive or visually impaired by the referring ophthalmologist. Overall, 12% of these children tested within the normal range, 53% had grating acuities better than 20/200 but below normal, 27% had acuities below 20/200, and 8% were not measurable. These results suggest that a wide range of visual potential exists in this population and that some of these children may benefit from visual aids and training.

Adolescent↗

PubMedDate not supplied

Breast-feeding and optimal visual development.

The goal of the present study was to determine whether dietary supply of omega-3 essential fatty acid (EFA) influences visual development in healthy pre-term and full-term infants. Visual status was examined in human milk-fed infants (ample dietary omega-3 EFA supply) and corn oil-based formula-fed infants (no dietary omega-3 EFA; standard formula prior to 1987). At 57 weeks postconception (4 months adjusted age), both pre-term and full-term human milk-fed infants had significantly better visual evoked potential (VEP) and forced-choice preferential-looking (FPL) acuity than formula-fed infants. Acuity was correlated with a dietary omega-3 sufficiency index from red blood cell membranes obtained at 57 weeks postconception. At 36 months, full-term human milk-fed children had significantly better random dot stereo acuity and letter matching ability than formula-fed children. Stereo acuity and performance on the letter matching test were correlated with a dietary omega-3 sufficiency index from red blood cell membranes obtained at 4 months. These results suggest that dietary omega-3 fatty acids play an important role in visual development.

Breast Feeding↗

PubMedDate not supplied

Random dot stereoacuity of preschool children. ALSPAC "Children in Focus" Study Team.

PURPOSE: Commercially available book-format random dot stereopsis tests for children are quick and simple to use, but provide accurate measurement of stereoacuity only in children age 5 years or older. Alternative methods for preschool children provide only pass/fail information or require lengthy laboratory-based protocols. To address the need for a quick and accurate measure of random dot stereoacuity in the preschool age range, we developed a new book-format random dot stereoacuity test. METHODS AND RESULTS: A total of 25 potential shapes for the new test were evaluated in a group of 43 healthy full-term children aged 3 years +/- 2 months. Eleven shapes that were identified successfully by more than 95% of the 3-year-olds were selected to be incorporated into the preschool stereotest. The preschool random dot stereotest books were administered to more than 1000 normal children and pediatric patients in multiple settings: a research laboratory (Retina Foundation SW), a population screening project (University of Bristol, UK), eye clinics (Children's Medical Center, Dallas, Tex), and a day care center (Federal University, São Paulo, Brazil). Randot, Lang 1, Frisby, or Titmus stereoacuity tests also were administered. Orthoptic or ophthalmic examinations were obtained for all children as a gold standard. Outcome measures were success rate and concordance with the clinical examination. Sensitivity, specificity, and accuracy exceeded 0.90 both in clinical and screening settings. CONCLUSIONS: The preschool random dot books had a higher success rate than other tests in the preschool age range and provided accurate measurement of stereoacuity in the 3- to 5-year-old age range.

Child, Preschool↗