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Biomedical subjects

A R O'Connor

Publications and source records attributed to A R O'Connor.

11 recordsLinked to original sources
PubMed2006

Change of refractive state and eye size in children of birth weight less than 1701 g.

AIMS: To determine the refractive status and ocular dimensions of a cohort of children at age 10-12 years with birth weight below 1701 g, and also the relation between the neonatal ophthalmic findings and subsequent refractive state. METHODS: 293 low birthweight children who had been examined in the neonatal period were assessed at 10-12 years of age. The examination consisted of autorefraction, keratometry, and A-scan. Results of right eyes were compared with published normative data. RESULTS: 293 of the birth cohort of 572 children consented to participate. The average mean spherical equivalent (MSE) in the low birthweight cohort was +0.691 dioptre, significantly higher than the control data (+0.30D, p = 0.02). The average change in MSE over the 10-12 year period was -1.00 dioptre (n = 256), but only 62.1% of cases showed a shift in refractive error of the appropriate magnitude and direction. The presence of any retinopathy of prematurity (ROP) increases the risk of developing anisometropia sixfold. CONCLUSIONS: Low birth weight and ROP both significantly impact the refractive state in the long term. At age 10-12 years children born preterm have an increased prevalence of all refractive errors. In low birthweight children refractive state is relatively stable over the first decade of life with a shift towards myopia of 1 dioptre.

Birth Weight↗
PubMed2006

Do infants of birth weight less than 1500 g require additional long term ophthalmic follow up?

AIM: To survey existing ophthalmic follow up protocols in the United Kingdom for very low birthweight (VLBW) children. In addition, relative risk analysis was performed using data from a cohort study to assess which factors (birth weight, gestational age, retinopathy of prematurity (ROP) status) led to a high risk of developing amblyogenic factors. METHODS: Questionnaires were sent to every orthoptic department in the United Kingdom (n = 288) for information on their policy on the follow up of VLBW children. RESULTS: Responses were received from 125 departments (43%). There was a large variation in criteria used for follow up; 21% of respondents using birth weight (BW) and gestational age (GA), 22% using stage 3 or treated ROP, the remainder using a combination of these factors. There was no consensus regarding when follow up should commence (from 3 months to 3 years) or cease (1-8 years). Relative risk analysis revealed that birth weight under 1500 g, GA under 33 weeks, and the presence of severe ROP were significant risk factors for developing one or more amblyogenic factors. CONCLUSION: There is no consensus on whether VLBW children need to be reviewed. There is a greatly increased risk of ophthalmic deficits in those with severe ROP or severe neurological disorders, and also in those with mild or no ROP. Children in the latter group who are not routinely followed up, have a high risk of developing treatable refractive errors and strabismus. This raises the question of whether an additional screening examination is merited.

Age Factors↗
PubMed2004

A comparison of findings on parents' and teachers' questionnaires, and detailed ophthalmic and psychological assessments.

BACKGROUND: Questionnaires are important tools used to gain information about health and level of function in different domains. AIMS AND METHODS: To determine the degree of agreement between questionnaires, administered to parents and teachers, and ophthalmic and psychological examinations in a cohort of 309 low birth weight children (<1701 g) at age 10-13 years. RESULTS: A total of 90.9% of cases showed agreement between the question on distance vision and clinical assessment, and agreement for the near vision question was 83%. However, the correlation on an individual basis was only fair (kappa = 0.46, distance vision) to poor (kappa = 0.2, near vision). The overall agreement for the questions on cognitive ability was better than the correlation, whereas the questions on reading and mathematical ability showed low agreement and low correlation. CONCLUSION: Questionnaire assessment of vision and cognitive ability is more suitable for studying the outcome of a large population than for identifying deficits in individuals.

Adolescent↗
PubMed2004

Visual function in low birthweight children.

AIM: To determine the visual functions, at age 10-12 years, of a geographically based cohort of children of birth weight less than 1701 g. The results were compared to a group of children born at full term. METHODS: 572 low birthweight (LBW) "low birthweight cohort" children who had been examined in the neonatal period were invited for review at 10-12 years of age. 169 11 year old schoolchildren born at full term were also recruited, "school cohort." Visual acuity (at distance and near), contrast sensitivity, colour vision, and visual fields were measured. RESULTS: 293 of the original 572 participants consented to a further examination. Compared to the school cohort of children born at term the low birthweight cohort showed significantly lower near and distance acuities and contrast sensitivity (p<0.001 for all uniocular and binocular measures). Retinopathy of prematurity (ROP) was a very poor predictor of outcome and multivariate analysis did not identify any key neonatal factors as predictors of long term visual outcome. CONCLUSIONS: Low birthweight children have a small but statistically significant deficit in both visual acuity and contrast sensitivity. Low birth weight and ROP both impact on long term visual functions.

Amblyopia↗
PubMed2001

Preterm birth and visual development.

Visual impairment, oculomotor abnormalities, and refractive error are prevalent among children with a history of preterm birth. These conditions may result from exposure of the immature visual system to early visual stimulation, from nutritional deficits that occur following the abrupt loss of placental maternal-to-fetal transfer of essential nutrients, and as secondary effects of systemic disease or complications associated with preterm birth. This chapter provides an overview of the structural and functional maturation of the visual system of the healthy preterm infant and of several forms of visual impairment that are prevalent in the low birth weight population.

Electroretinography↗
PubMed1998

Lower-limb deep venous thrombosis: direct MR imaging of the thrombus.

PURPOSE: To determine the feasibility of diagnosing deep venous thrombosis (DVT) with direct three-dimensional magnetic resonance (MR) imaging of the thrombus. MATERIALS AND METHODS: Eighteen patients with proved DVT at conventional venography were evaluated with a magnetization-prepared three-dimensional blood- and fat-suppressed MR imaging sequence. The presence and extent of thrombosis on the MR images were compared with the findings at conventional venography. RESULTS: At MR imaging, DVT was visualized in 17 of the 18 patients. MR imaging demonstrated greater proximal extent of the thrombosis in four patients, asymptomatic contralateral thrombosis in one, involvement of the deep femoral vein in five, and involvement of the superficial venous system in three. CONCLUSION: Direct MR imaging of clots appears capable of demonstrating venographically diagnosed DVT. This MR imaging technique is noninvasive, quick, and repeatable and allows a survey of the whole lower-limb venous system. Detection of thrombosis relies on the formation of methemoglobin, which appears to be sufficiently rapid to allow use of this technique in the clinical setting. Changes in the signal from clot over time may allow estimation of the age of the thrombus.

Feasibility Studies↗
PubMedDate not supplied

Cyclic scheduling.

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Computers↗