Higher-order aberrations in amblyopia:an analysis of pre- and post-wavefront-guided laser refractive correction

For more than a century it has been known that the eye is not a perfect optical system, but rather a system that suffers from aberrations beyond conventional prescriptive descriptions of defocus and astigmatism. Whereas traditional refraction attempts to describe the error of the eye with only two parameters, namely sphere and cylinder, measurements of wavefront aberrations depict the optical error with many more parameters. What remains questionable is the impact these additional parameters have on visual function. Some authors have argued that higher-order aberrations have a considerable effect on visual function and in certain cases this effect is significant enough to induce amblyopia. This has been referred to as ‘higher-order aberration-associated amblyopia’. In such cases, correction of higher-order aberrations would not restore visual function. Others have reported that patients with binocular asymmetric aberrations display an associated unilateral decrease in visual acuity and, if the decline in acuity results from the aberrations alone, such subjects may have been erroneously diagnosed as amblyopes. In these cases, correction of higher-order aberrations would restore visual function. This refractive entity has been termed ‘aberropia’. In order to investigate these hypotheses, the distribution of higher-order aberrations in strabismic, anisometropic and idiopathic amblyopes, and in a group of visual normals, was analysed both before and after wavefront-guided laser refractive correction. The results show: (i) there is no significant asymmetry in higher-order aberrations between amblyopic and fixing eyes prior to laser refractive treatment; (ii) the mean magnitude of higher-order aberrations is similar within the amblyopic and visually normal populations; (iii) a significant improvement in visual acuity can be realised for adult amblyopic patients utilising wavefront-guided laser refractive surgery and a modest increase in contrast sensitivity was observed for the amblyopic eye of anisometropes following treatment (iv) an overall trend towards increased higher-order aberrations following wavefront-guided laser refractive treatment was observed for both visually normal and amblyopic eyes. In conclusion, while the data do not provide any direct evidence for the concepts of either ‘aberropia’ or ‘higher-order aberration-associated amblyopia’, it is clear that gains in visual acuity and contrast sensitivity may be realised following laser refractive treatment of the amblyopic adult eye. Possible mechanisms by which these gains are realised are discussed.

Premonitory urges for tics in adult patients with Tourette syndrome

Objective: Patients with Tourette syndrome (TS) often report characteristic sensory experiences, also called premonitory urges (PUs), which precede tic expression and have high diagnostic relevance. This study investigated the usefulness of a scale developed and validated in children and adolescents-the Premonitory Urge for Tics Scale (PUTS, Woods et al., 2005 [13])-for the assessment of PUs in adult patients with TS. Method: Standard statistical methods were applied to test the psychometric properties of the PUTS in 102 adult TS outpatients recruited from two specialist clinics in the United Kingdom. Results: The PUTS showed good acceptability and endorsement rates, with evenly distributed scores and low floor and ceiling effects. Item-total correlations were moderate to strong; PUTS total scores were significantly correlated with quantitative measures of TS severity. The PUTS showed excellent internal consistency reliability (Cronbach's alpha=0.85) and Spearman's correlations demonstrated satisfactory convergent and discriminant validity. Conclusions: Although originally devised to assess urges to tic in young patients with TS, the PUTS demonstrated good psychometric properties in a large sample of adults recruited at specialist TS clinics. This instrument is therefore recommended for use across the life span as a valid and reliable self-report measure of sensory experiences accompanying tic expression. © 2013 The Japanese Society of Child Neurology.

Diagnosis of central venous catheter related infection in adult patients

Intravascular catheters are one of the main causes of bacteraemia and septicaemia in hospitalised patients and continue to be associated with a significant morbidity and mortality. Two main types of infections occur, they can be either localised at the catheter insertion site of systemic with a septicaemia. The clinical parameters related to these infections are presented. The laboratory diagnosis of these infections is also extensively reviewed and recommendations are made as to the most appropriate diagnostic method to be used. © 2005 The British Infection Society. Published by Elsevier Ltd. All rights reserved.