Orbital cellulitis vs allergic reaction to hyaluronidase as the cause of periorbital oedema.
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Cellulitis↗
Biomedical subjects
P M Pennefather
Publications and source records attributed to P M Pennefather.
Regionalisation of retinopathy of prematurity (ROP) screening improves compliance with guidelines: an audit of ROP screening in the Northern Region of England.
AIMS: This project was designed to determine whether a coordinated regional strategy can improve the implementation of national guidelines for screening for retinopathy of prematurity (ROP), and to identify causes for failure of compliance. METHODS: Retrospective case note audit relating to two periods, 1990-1 and 1994, involving all 17 neonatal intensive care units in the Northern Region of England. Between the two periods, a regional strategy was instituted in an endeavour to improve compliance. Babies born in or admitted to the units during the study periods who were eligible for ROP screening were included. Screening performance was assessed against a standard of 100% compliance with the guidelines. In the second audit period compliance with subsidiary standards was also measured, and reasons for failure were identified. RESULTS: Compliance improved from 47% (262/558) in the first audit cycle to 73% (264/360) in the second. Subgroup analysis in this second cycle indicated better compliance (93.3%) in higher risk babies (< or = 29 weeks' gestational age). Babies transferred between units, discharged home before screening, or who failed to qualify for screening on one of the two defined criteria, were more likely to be missed. CONCLUSION: A carefully implemented regional approach to screening resulted in a higher uptake for babies most at risk. Simple recommendations are made to achieve further improvement in compliance with the guidelines. The wider implications for screening in other conditions and in other areas and specialties are highlighted.
England↗
Fluoroquinolones: place in ocular therapy.
The fluoroquinolones have become widely used antibacterial agents in the treatment of ocular infections, with topical, intravitreal and systemic routes of administration being used. In general, fluoroquinolones (such as ciprofloxacin, ofloxacin, lomefloxacin and norfloxacin) have good activity against gram-negative and gram-positive bacteria. Therapeutic concentrations are achieved in the cornea after topical administration so that the fluoroqinolones have largely replaced combination therapy for the treatment of bacterial keratitis. However, a second line agent is needed when resistance is likely, such as in disease caused by streptococcal species. Reversal of resistance to quinolones may not occur with withdrawal of the antibacterial. This stresses the importance of prudent prescribing to reduce the occurrence of resistance to quinolones. When used in therapeutic topical dosages, corneal toxicity does not occur. Similarly, retinal toxicity is not seen when fluoroquinolones are used at therapeutic dosages, systemically or topically. Corneal precipitation occurs, particularly with ciprofloxacin and to a lesser extent norfloxacin, but does not appear to interfere with healing. In the treatment of endophthalmitis there is reasonable penetration of systemic fluoroquinolones into the vitreous but sufficiently high concentrations to reach the minimum inhibitory concentration for 90% of isolates (MIC90) of all important micro-organisms may not be guaranteed. Systemic administration may be useful for prophylaxis after ocular trauma.
Animals↗
Contour integration deficits in anisometropic amblyopia.
PURPOSE: Previous retrospective studies have found that integration of orientation information along contours defined by Gabor patches is abnormal in strabismic, but not in anisometropic, amblyopia. This study was conducted to reexamine the question of whether anisometropic amblyopes have contour integration deficits prospectively in an untreated sample, to isolate the effects of the disease from the effects of prior treatment-factors that may have confounded the results in previous retrospective studies. METHODS: Contour detection thresholds, optotype acuity, and stereoacuity were measured in a group of 19 newly diagnosed anisometropic amblyopes before initiation of occlusion therapy. Contour detection thresholds were measured using a card-based procedure. RESULTS: Significant interocular differences in contour detection thresholds were present in 14 of the 19 patients with anisometropic amblyopia. CONCLUSIONS: Contour integration deficits are a common, but not universal, finding in untreated anisometropic amblyopia. Differences in the prevalence of contour integration deficits between the present study and that of another study may lie in differences in treatment history and/or in the sensitivity of the two different contour integration tasks.
Adolescent↗
A new test of contour integration deficits in patients with a history of disrupted binocular experience during visual development.
Previous studies have suggested that the integration of orientation information across space is impaired in amblyopia. We developed a method for quantifying orientation-domain processing using a test format that is suitable for clinical application. The test comprises a graded series of cards where each card includes a closed path (contour) of high contrast Gabor signals embedded in a random background of Gabor signals. Contour visibility in both normals and patients with histories of abnormal binocular vision depends jointly on the spacing of elements on the contour as well as background element density. Strabismic amblyopes show significant degradation of performance compared to normals. Small but significant losses in sensitivity were also observed in a group of non-amblyopic strabismus patients. Threshold measurements made with contrast reducing diffusers indicated that the amblyopic loss is not due to the reduced contrast sensitivity of the amblyopic eye. An abnormal pattern of long-range connectivity between spatial filters or a loss of such connectivity appears to be the primary source of contour integration deficits in amblyopia and strabismus.
Adolescent↗
Ocular abnormalities associated with cerebral palsy after preterm birth.
PURPOSE: To document the ocular abnormalities in children with cerebral palsy (CP) after premature birth. METHODS: All the children born before 32 weeks gestation between 1 January 1990 and 31 December 1991 in a geographically defined population of approximately 3 million, were examined by an ophthalmologist and a paediatrician at 2 years old. RESULTS: Five hundred and fifty-eight children (98.8% of the study group) were examined, of whom 41 had disabling CP and 13 had non-disabling CP. Children with CP had a higher incidence of abnormalities compared with children without CP: cicatricial retinopathy of prematurity occurred in 8 children with CP (14.8%) compared with 8 without CP (1.6%, p < 0.0001), cortical visual impairment occurred in 6 with CP (11.1%) compared with 1 child without CP (0.2%, p < 0.0001) and concomitant strabismus in 28 with CP (51.9%) compared with 42 without CP (8.4%, p < 0.0001). The prevalence of refractive error without other ocular abnormalities was similar for children with CP (4/54, 7.4%) and those without CP (54/504, 10.7%, p = 0.90). Significant ocular abnormalities had been previously unrecognised in 8 children with CP (14.8%). CONCLUSION: There are some differences between these results and previous series. These differences probably reflect the fact that previous work has studied severe CP of more diverse aetiology. The high frequency of abnormalities highlights the importance of ocular assessment of these children.
Cerebral Palsy↗
Risk factors for strabismus in children born before 32 weeks' gestation.
AIM: To investigate risk factors associated with strabismus in children born prematurely. METHODS: Prospective study of all children born before 32 weeks' gestation between 1 January 1990 and 31 December 1991 in a geographically defined population of approximately 3 million in the Northern Region of the United Kingdom. All children were examined aged 2 years by the same ophthalmologist and paediatrician. RESULTS: 558 children (98.6% of study group) were examined. Logistic regression showed an increased risk of strabismus in children with cicatricial retinopathy of prematurity (p=0.02), refractive error (p=0.003), family history of strabismus (p<0.0001), and poor neurodevelopmental outcome (p<0.0001), in particular impaired locomotor skills (p=0.008) and hand-eye coordination (p=0. 001). Gestational age and regressed acute ROP were not independent risk factors for strabismus (p=0.92 and 0.85 respectively). CONCLUSIONS: This study has identified factors which are independently related to strabismus (although not necessarily causative) and others which are related only indirectly. This may contribute both to the management of children born prematurely and to future studies of the aetiology of strabismus.
Child Development↗
Bias due to incomplete follow up in a cohort study.
AIM: To investigate the bias introduced by incomplete follow up in a cohort study of ocular outcome after premature birth. METHODS: A geographically defined cohort of children born before 32 weeks' gestation was prospectively recruited at birth to study the ocular outcome at 2 years. On the basis of attendance at 2 years, the children's families were allocated to one of three groups: group 1 attended for follow up, group 2 were difficult to trace, and group 3 were very reluctant for assessment. All children were examined by a single ophthalmologist, masked to these groupings. RESULTS: 558 children (98.8% of study group) were examined, of whom 505 were in group 1, 20 in group 2, and 33 in group 3. The groups which were more difficult to study (groups 2 and 3) showed a significantly higher prevalence of ocular abnormalities, including strabismus (p=0. 02) and cicatricial retinopathy of prematurity (p=0.002) compared with those attending for follow up. Further, not all of these cases could have been identified by review of the children's previous records. Ocular abnormalities would be underestimated by 16% (11.3% in group 1 compared with 13.4% in the total cohort, p=0.77). CONCLUSIONS: This study suggests that the prevalence of abnormalities would be underestimated by incomplete follow up, as those subjects who were most difficult to obtain for study had a significantly higher prevalence of abnormalities.
Bias↗
Contour detection threshold: repeatability and learning with 'contour cards'.
Human observers are able to locate contours that are defined solely on the basis of long-range, orientation-domain correlations. The integrity of the mechanisms responsible for second-order contour detection is disrupted by amblyopia (Kovacs et al., 1996; Hess et al., 1997) and it is therefore of interest to develop methods for assessing pediatric patients undergoing treatment for amblyopia. In this study, we have determined the inter-observer and test-retest reliability of a card-based test of second-order contour integration. The magnitude of practice effects was also assessed in both adult and pediatric patient groups. Contour detection thresholds were measured for a closed contour, defined by Gabor patches, embedded in a randomly oriented Gabor-patch background. The visibility of the contour was controlled by varying the density of the background elements. Thresholds, defined in terms of the ratio of contour element spacing to average background spacing were measured with a clinical staircase procedure. Thresholds measured by two observers differed on average by 0.023 +/- 0.075 or about one half the increment between cards. Children and adults showed only small practice effects (0.022 +/- 0.051 vs 0.053 +/- 0.077, respectively) and average unsigned differences between repeated measures were equivalent to approximately 1 card across groups. A card-based test of second-order contour integration produces reliable estimates of contour integration performance in normal and amblyopic observers, including children.
Adult↗
Pulsatile ocular blood flow and intraocular pressure during retrobulbar injection of lignocaine: influence of additives.
PURPOSE: To assess the influence of adrenaline and hyaluronidase on pulsatile ocular blood flow and intraocular pressure changes during retrobulbar anesthesia. METHOD: Patients undergoing cataract surgery under local anesthesia received a 5-mL retrobulbar injection of lignocaine with either adrenaline, hyaluronidase, or no addition. Continuous pneumotonometry was performed using the OBF tonograph (OBF Labs, Chippenham, UK), which automatically derives pulsatile ocular blood flow values. Measurements were taken before and one minute after injection, and changes were compared between groups to evaluate the effects of changing the constituents of the injection. RESULTS: There was a marked decrease in pulsatile ocular blood flow during injection in all groups. In the group receiving lignocaine with hyaluronidase, the decrease in pulsatile ocular blood flow (mean -141 microL/min) was significantly less than in either the group receiving lignocaine and adrenaline (mean -249 microL/min) or the group receiving lignocaine alone (mean -245 microL/min). There was no significant change in intraocular pressure in any group. CONCLUSION: Hyaluronidase appears to lessen the reduction in pulsatile ocular blood flow. Injection volumes of 5 mL need not cause significant intraocular pressure change.
Anesthesia, Local↗
Refractive errors in children born before 32 weeks gestation.
PURPOSE: To document the refractive errors in a cohort of children born before 32 weeks gestation. METHODS: All children born before 32 weeks gestation between 1 January 1990 and 31 December 1991 to mothers resident in the Northern Region of the National Health Service were examined at 2 years old (n = 558). RESULTS: Stage 3 or worse retinopathy of prematurity (ROP) was associated with myopia. In those not developing stage 3 or worse ROP, the refractive errors were myopia in 1.5%, hypermetropia > 4 dioptres (D) in 5.4%, anisometropia > 1 D in 1.1% and astigmatism > 1.25 D in 5.7%. CONCLUSION: The incidence of refractive errors in those not developing stage 3 or worse ROP was similar to that in the general population.
Acute Disease↗
Retinopathy of prematurity in a controlled trial of prophylactic surfactant treatment.
AIMS: To investigate the incidence of acute and cicatricial retinopathy of prematurity (ROP) in a cohort of premature neonates entered into a randomised, multicentre trial of prophylactic exogenous surfactant for respiratory distress syndrome (RDS) compared with controls receiving surfactant only if severe RDS developed. METHODS: The incidence of acute and cicatricial ROP was assessed in 304 neonates born at less than 30 weeks' gestation in a geographically defined population of approximately three million. RESULTS: There was a trend towards improved survival in the group receiving prophylactic surfactant with 102/151 (67.5%) surviving compared with 82/141 controls (58.2%, p = 0.12). The prophylactic surfactant group would be expected to have an increased risk of ROP due to improved survival, particularly of the most premature infants. However, there was no statistically significant difference in the incidence of acute ROP between the two groups and the incidence of cicatricial ROP was lower in the group receiving prophylactic surfactant (4/100 survivors, 4.0%) compared with neonates receiving rescue surfactant as required (6/81, 7.4%). This difference did not reach statistical significance (p = 0.35). CONCLUSION: The trend for a lower incidence of cicatricial ROP in those neonates treated with prophylactic surfactant compared with the rescue surfactant group, despite improved survival, suggests that the use of prophylactic surfactant also had a beneficial effect on the development of cicatricial ROP.
Drug Combinations↗
Ocular outcome in children born before 32 weeks gestation.
Ocular outcome was assessed in a 2 year cohort of all children born before 32 weeks gestation within a geographically defined population of approximately 3 million. Five hundred and sixty-five children were born within the study period; 558 children (98.8% of the study group) were assessed at approximately 2 years old. There was a high incidence of abnormalities, particularly strabismus (70, 12.5%), cortical visual loss (7, 1.3%), sequelae of retinopathy of prematurity (16, 2.9%) and other significant refractive errors (69, 12.7%). These data provide a recent estimate of gestational age-specific prognosis and suggest that follow-up yields a significant proportion of children with visual abnormalities who could benefit from treatment.
Child, Preschool↗