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Biomedical subjects

A R Fielder

Publications and source records attributed to A R Fielder.

At least 19 recordsLinked to original sources

The temporal retinal vessel angle and infants born preterm.

AIM: To determine the temporal retinal vessel angle in babies and its relation to preterm birth. METHODS: Digital images were obtained during routine screening for retinopathy of prematurity (ROP). The temporal retinal vessel angle was measured in 164 eyes of 82 babies born "very preterm" (24-27 weeks gestational age (GA)), "preterm" (28-31 weeks GA), and "near term" (>/=32 weeks GA). RESULTS: Mean temporal vessel angle (TVA) for all three GA groups together is 80.0 degrees (SD 17.0 degrees ) for the right eye and 80.5 degrees (16.7 degrees ) for the left eye. The range is right eye 59-106 degrees , left eye 69-97 degrees , with 95% data above 67 degrees for the right and 63 degrees for the left eye. For babies born near term, TVA is 82 degrees in each eye. There is a high degree of interocular symmetry between right and left eyes and a statistically insignificant trend for increasing TVA with increasing GA. The presence and stage of ROP affected one parameter of the left eye alone. CONCLUSIONS: These data provide normative data on the TVA in babies and will facilitate, especially if there is interocular asymmetry, determining whether there is macular displacement.

Fovea Centralis↗

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↗

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↗

The first cut is the deepest: basic surgical training in ophthalmology.

PURPOSE: To examine the basic surgical training received by Senior House Officers (SHOs) in ophthalmology and the influence on training of sociodemographic and organisational factors. METHODS: Cross-sectional survey of SHOs in recognised UK surgical training posts asking about laboratory training and facilities, surgical experience, demographic details, with the opportunity to add comments. RESULTS: A total of 314/466 (67%) questionnaires were returned. In all, 67% had attended a basic surgical course, 40% had access to wet labs and 39% had spent time in a wet lab in the previous 6 months. The mean number of part phakoemulsification (phako) procedures performed per week was 0.79; the mean number of full phakos performed per week was 0.74. The number of part phakos performed was negatively correlated, and the number of full phakos completed was positively correlated, with length of time as an SHO. Respondents who had larger operating lists performed more full phakos per week (P<0.001). Compared to men, women were less likely to have access to a wet lab (P=0.013), had completed fewer full phakos per week (P=0.003), and were less likely to have completed 50 full phakos (P=0003). SHOs' comments revealed concerns about their limited 'hands on' experience. CONCLUSIONS: There are significant shortcomings in the basic surgical training SHOs receive, particularly in relation to wet lab experience and opportunities to perform full intraocular procedures. SHOs themselves perceive their training as inadequate. Women are disadvantaged in both laboratory and patient-based training, but minority ethnic groups and those who qualified overseas are not.

Adult↗

UK population based study of severe retinopathy of prematurity: screening, treatment, and outcome.

BACKGROUND: Retinopathy of prematurity (ROP) is one of the few causes of childhood blindness in which severe vision impairment is largely preventable. Ophthalmic screening for ROP is required to identify disease that requires treatment whereby the development of potentially blinding disease can be minimised. OBJECTIVES: To make the first UK population based estimate of the incidence of babies with severe ROP (stage 3 or more); to document their clinical characteristics and management and to evaluate the appropriateness of current ROP screening guidelines in the UK. PATIENTS: Cases were recruited through a national surveillance programme with 1 year ophthalmic follow up and data from clinician completed questionnaires. RESULTS: Between 1 December 1997 and 31 March 1999, 233 preterm babies with stage 3 ROP were identified. Severity (location, extent, and presence of plus disease) was associated with degree of prematurity, most severe in the most premature babies. Fifty nine percent were treated. The UK screening protocol was followed in two thirds of cases, but in the remainder it was begun too late or was too infrequent. Three quarters of the cases were followed up at 1 year, and 13% had a severe vision deficit as a result of ROP. CONCLUSIONS: Visual deficit as a result of ROP in premature babies continues to be a severe disability in some of the survivors of neonatal intensive care. Further efforts are needed to organise treatment regionally to improve outcome and standards of practice.

Birth Weight↗

Cytomegalovirus Retinitis in infancy.

PURPOSE: To describe the presentation of cytomegalovirus retinitis (CMVR) in a series of infants. METHODS: Immunocompromised infants with either HIV or systemic cytomegalovirus (CMV) were examined for CMVR. Ocular involvement was recorded and monitored by digital imaging. RESULTS: Five infants were detected to have CMVR. All the infants demonstrated changes within the macula. One infant progressed from a fine granular pattern to fulminant CMVR. CONCLUSION: Infants under a year with CMVR have a predilection for the disease to present at the macula, in contrast to the presentation in adults, which tends to involve more peripheral parts of the retina.

AIDS-Related Opportunistic Infections↗

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↗

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↗

Refractive adaptation in amblyopia: quantification of effect and implications for practice.

AIM: To describe the visual response to spectacle correction ("refractive adaptation") for children with unilateral amblyopia as a function of age, type of amblyopia, and category of refractive error. METHOD: Measurement of corrected amblyopic and fellow eye logMAR visual acuity in newly diagnosed children. Measurements repeated at 6 weekly intervals for a total 18 weeks. RESULTS: Data were collected from 65 children of mean (SD) age 5.1 (1.4) years with previously untreated amblyopia and significant refractive error. Amblyopia was associated with anisometropia in 18 (5.5 (1.4) years), strabismus in 16 (4.2 (0.98) years), and mixed in 31 (5.2 (1.5) years) of the study participants. Mean (SD) corrected visual acuity of amblyopic eyes improved significantly (p<0.001) from 0.67 (0.38) to 0.43 (0.37) logMAR: a mean improvement of 0.24 (0.18), range 0.0-0.6 log units. Change in logMAR visual acuity did not significantly differ as a function of amblyopia type (p = 0.29) (anisometropia 0.22 (0.13); mixed 0.18 (0.14); strabismic 0.30 (0.24)) or for age (p = 0.38) ("under 4 years" 0.23 (0.18); "4-6 years" 0.24 (0.20); "over 6 years" 0.16 (0.23)). CONCLUSION: Refractive adaptation is a distinct component of amblyopia treatment. To appropriately evaluate mainstream therapies such as occlusion and penalisation, the beneficial effects of refractive adaptation need to be fully differentiated. A consequence for clinical practice is that children may start occlusion with improved visual acuity, possibly enhancing compliance, and in some cases unnecessary patching will be avoided.

Adaptation, Ocular↗

The state of basic surgical training in the UK: ophthalmology as a case example.

Concern is being expressed about the state of basic surgical training in the context of growing demands to improve service provision in the National Health Service. Taking ophthalmology as a case example, we sent questionnaires to all 466 senior house officers (SHOs) in recognized surgical training posts in England, Wales, Scotland and Northern Ireland. The main outcome measures were intraocular surgery performed in the previous two weeks and since starting as an SHO in ophthalmology; access to protected teaching time or cases on theatre lists; and supervision during surgery. Phakoemulsification, the most common type of cataract surgery, was used as a generic indicator of intraocular procedures. 314 (67%) of the SHOs responded. Of those working in the hospital in the previous two weeks, 50% had performed at least one component part of a phakoemulsification (phako) operation and 44% had performed at least one full phako operation. The average number of full phako operations done per week was 0.741. 77% reported some protected surgical teaching time over the two weeks and those with protected teaching time reported more full phako operations per week. Of those who had performed at least one surgical procedure in the previous two weeks, 79% had been supervised by a consultant. Of those who had completed two or more years' training as an SHO, only 42% met the Royal College of Ophthalmologists minimum requirement of 50 complete intraocular operations performed under supervision. Women were less likely than men, and SHOs in district general hospitals were less likely than those in teaching hospitals, to have achieved this target. As many as half the SHOs in ophthalmology are not receiving an adequate basic surgical training. If this continues it may prove difficult to train sufficient new surgeons to an acceptable standard to meet the increasing demands of an ageing population. This is not an issue for ophthalmology alone but for all surgical specialties.

Adult↗

Defining and measuring treatment outcome in unilateral amblyopia.

AIM: To offer a critique of current methods of defining amblyopia treatment outcome and to examine alternative approaches. METHOD: Literature appraisal and descriptive case presentations. RESULTS: Currently, the outcome of amblyopia treatment is expressed as the number of acuity chart lines gained or, alternatively, achievement of an arbitrarily adopted level of visual acuity. As binocular vision is optimised with equal visual input from each eye the authors propose that the optimum outcome of amblyopia therapy is to achieve a visual acuity in the amblyopic eye equal to that of its fellow. In addition, improvement should be graded as the proportion of change in visual acuity with respect to the absolute potential for improvement (that is, that pertaining in the fellow eye at end of treatment). CONCLUSIONS: There are two methods of appropriately describing the outcome of amblyopia treatment: firstly, by the difference in final visual acuity of amblyopic and fellow eye (residual amblyopia); secondly, the proportion of the deficit corrected.

Amblyopia↗

Semiautomated computer analysis of vessel growth in preterm infants without and with ROP.

AIMS: To measure characteristics of the retinal blood vessels close to the optic disc in full term and preterm infants, with and without retinopathy of prematurity (ROP), using digital imaging. To determine whether these measures are indicative of the presence or severity of ROP in the retinal periphery. METHODS: 52 digital fundus images from 42 babies were analysed with a semiautomated analysis program developed at Imperial College London. Analysis was limited to the principal temporal vessels close to the optic disc: recording venular diameter and arteriolar diameter and tortuosity. RESULTS: Each result was categorised by the gestational age of the infant ("very premature" 24-27 weeks, "moderately premature" 28-31 weeks, and "near term" > or =32 weeks) and by the highest stage of ROP present ("no ROP," "mild ROP" stage 1 or 2, and "severe ROP" stage 3). Arteriolar tortuosity was found to vary significantly (Kruskal-Wallis p=0.002) with ROP severity. Although venular and arteriolar diameters increased monotonically with ROP severity the differences were not significant. Venular diameter, arteriolar diameter, and arterial tortuosity did not vary significantly between gestational age groups. CONCLUSIONS: This study confirms it is possible to quantify the size and tortuosity of retinal blood vessels in term and preterm babies using digital image analysis software. This method detected significant increases in arteriolar tortuosity with increasing ROP severity.

Case-Control Studies↗

Retinopathy of prematurity in the UK I: the organisation of services for screening and treatment.

AIMS: To ascertain how closely services for the screening and treatment of retinopathy of prematurity (ROP) were organised on a national level in 1995. METHODS: Questionnaires about the local arrangements for the screening and treatment of retinopathy of prematurity (ROP) were sent to the entire consultant membership (n = 648) of the Royal College of Ophthalmologists (RCOphth) and to the clinical directors (n = 259) of neonatal units and other units caring for preterm babies in the UK in 1995. RESULTS: 568/648 of UK consultants (88%) and 15 non-consultant ophthalmologists and 210/259 paediatricians (81%) and 19% paediatricians in non-neonatal units responded. Thirty-one per cent responding ophthalmologists were involved in the ROP service: of these 64% screened babies, 34% screened and treated babies, while 1% ophthalmologists treated ROP but did not screen. Ninety-six per cent units caring for preterm babies had their babies screened for ROP and for almost 95% of the screening took place in the neonatal unit. About 8200 babies were screened in 1994; 277 developed stage 3, of whom 54% received treatment. Nine per cent (n = 14) and 5% (n = 8) treated babies became blind in one and both eyes respectively. A sessional commitment was identified for 9% ophthalmologists, but for less than half this was included in the contracted work programme. Sixty-five ophthalmologists treated babies with ROP, but only 10 treated more than five babies in 1994. Training needs were identified by 71 respondents. CONCLUSIONS: Several aspects of ROP screening and treatment services require improvement. Hopefully, reducing the number of identified screeners would increase skills, confidence and the ability to recognise severe disease requiring treatment, and also facilitate incorporation of this work into consultant work plans.

Blindness↗

Retinopathy of prematurity in the UK II: audit of national guidelines for screening and treatment.

AIMS: To ascertain how closely in 1995, neonatologists and ophthalmologists were adhering to the national guidelines for the screening of retinopathy of prematurity (ROP, 1990) and those for screening and treatment (1995). METHODS: Questionnaires about the local arrangements for the screening and treatment of retinopathy of prematurity were sent to the entire consultant membership (n = 648) of the Royal College of Ophthalmologists (RCOphth) and to the clinical directors (n= 259) of neonatal units in the UK in 1995. RESULTS: One hundered and eighty-three ophthalmologists in the UK were identified as undertaking ROP screening and/or treatment, and ROP screening took place in 207 neonatal units. Seventy-seven per cent of the ophthalmologists either complied with or exceeded recommendations for determining which babies required screening, while 7% used criteria that would have resulted in substantially fewer babies being screened. Only 17% units and 12% ophthalmologists provided written information for parents, although 66% ophthalmologists talked to the parents of babies they screened. There was a lack of clarity about responsibilities for ensuring the continuation of screening on transfer to another hospital or on discharge to home. There was a wide range of views on the ophthalmic criteria that determined when screening examinations could cease and on the indications for treatment. CONCLUSIONS: While ROP screening is almost universally adopted in the UK, there is a need for the process to be more efficient and effective. Despite the delay in reporting this survey several issues remain extant and future guidelines should clarify and refine the criteria for screening and treatment. There is a need for improved communication with parents, and particularly for written information.

Humans↗