Paediatric intraocular lens implants: accuracy of lens power calculations.

PurposeThis study aims to evaluate the accuracy of lens prediction formulae on a paediatric population.MethodsA retrospective case-note review was undertaken of patients under 8 years old who underwent cataract surgery with primary lens implantation in a regional referral centre for paediatric ophthalmology, excluding those whose procedure was secondary to trauma. Biometric and refractive data were analysed for 43 eyes, including prediction errors (PE). Statistical measures used included mean absolute error (MAE), median absolute error (MedAE), Student's t-test and Lin's correlation coefficient.ResultsThe mean PE using the SRK-II formula was +0.96 D (range -2.47D to +2.41 D, SD 1.33 D, MAE 1.38 D, MedAE 1.55, n=15). The mean PE was smaller using SRK/T (-0.18 D, range -3.25 D to +3.95 D, SD 1.70 D, MAE 1.30 D, MedAE 1.24, n=27). We performed an analysis of the biometry data using four different formula (Hoffer Q, Holladay 1, SRK-II and SRK/T). Hoffer Q showed a smaller MedAE than other formulae but also a myopic bias.ConclusionOur clinical data suggest SRK/T was more accurate in predicting post-operative refraction in this cohort of paediatric patients undergoing cataract surgery. Hoffer Q may have improved accuracy further.

Angle closure glaucoma in the Northern Ireland Diabetic Retinopathy Screening Programme.

PurposeTo ascertain the risk of angle closure glaucoma associated with mydriasis in the Northern Ireland Diabetic Retinopathy Screening Programme.MethodsA retrospective case note review was carried out, cross referencing hospital records with those of the screening programme, to identify episodes of angle closure glaucoma, which occurred within 14 days of a retinopathy screening episode involving pharmacological mydriasis.ResultsThree cases of angle closure following mydriasis for screening were identified. The incidence of angle closure within the screening programme was calculated to be 1 in 31 755 patients dilated or 0.75 patients per year.ConclusionAngle closure is a rare complication of mydriasis used in photographic screening for diabetic retinopathy. We advocate the provision of clear instructions to patients in screening programmes on when and how to access emergency ophthalmic care following dilation to prevent loss of vision in this rare event.

Variation in administration of cyclophosphamide and mesna in the treatment of childhood malignancies.

The objective of this study was to describe the variation in preparation and administration of cyclophosphamide, mesna, and hydration for the treatment of childhood malignancies within clinical trial protocol documents. All cyclophosphamide-containing cooperative group (Pediatric Oncology Group) protocols that were open at Dana-Farber Cancer Institute in April 1998 were evaluated. Among the 14 active protocols, there were 23 unique cyclophosphamide regimens. Marked variation existed in infusion rate, fluid type, and volume used for admixing cyclophosphamide and mesna, as defined in the "Treatment" section of the protocols that we evaluated. Further variation was found in the type, amount, and rate of infusion of prehydration and posthydration fluid. Internal inconsistency existed within the protocols pertaining to the administration methods described in the "Agent Information," "Treatment," and "Consent" sections of the written documents. Clinical trial protocol documents serve as reference material for health care providers who prescribe, dispense, and administer protocol chemotherapy. Misinterpretation of protocol documents and clinician orders are contributing factors in serious and deadly medication errors. Internal inconsistency within protocol documents and variation in drug administration across protocols is a potential source of error. We recommend improved accuracy, clarity, and internal consistency of protocol documents to improve patient safety and compliance with protocol specifications. In addition, the use of standard concentrations, volumes, and methods of administration of chemotherapeutic agents and accompanying fluids is recommended.

Progressive formation of inclusions in the striatum and hippocampus of mice transgenic for the human Huntington's disease mutation.

The significance of neuronal intranuclear inclusions (NIIs) and extranuclear inclusions (ENNIs) in the brains of patients with polyglutamine repeat diseases and transgenic mice modelling these diseases is hotly debated. We examined inclusions in the brains of mice transgenic for the human Huntington's disease mutation and found that their size, number and location varied markedly with age and neuronal phenotype. In striatum and hippocampus particularly, inclusions appeared at different times in different cell types. Further, the mechanism of formation of inclusions appears to be complex, with several distinct phases. These include a precipitous formation of NIIs followed by NII growth, and the concomitant formation ENNIs. While the timing of appearance of NIIs and ENNIs parallels the cognitive and motor decline of the mice, the precise role of NIIs and ENNIs is unknown. It has been variously suggested that NIIs may be deleterious, benign or beneficial. However, our data allows the possibility that each of these is possible, and suggest also that the role of inclusions changes with time. The precipitous formation of NIIs may play a protective role by removing polyglutamine, while the subsequent growth of NIIs may be deleterious, since it would allow other proteins to be sequestered into inclusions. The formation of ENNIs in neurites and synapses is also more likely to have deleterious than beneficial consequences for a cell. Thus, our study suggests that the relationship between inclusion formation and neurological dysfunction depends not only upon the phenotype of the neurons involved, but also upon the molecular composition and the subcellular localisation of the inclusions.