Laser treatment of drusen to prevent progression to advanced age-related macular degeneration.

BACKGROUND: Drusen are amorphous yellowish deposits beneath the sensory retina. People with drusen, particularly large drusen, are at higher risk of developing age-related macular degeneration (AMD). The most common complication in AMD is choroidal neovascularisation (CNV), the growth of new blood vessels in the centre of the macula. The risk of CNV is higher among patients who are already affected by CNV in one eye.It has been observed clinically that laser photocoagulation of drusen leads to their disappearance and may prevent the occurrence of advanced disease (CNV or geographic atrophy) associated with visual loss. OBJECTIVES: To examine the effectiveness and adverse effects of laser photocoagulation of drusen in AMD. SEARCH STRATEGY: We searched CENTRAL, MEDLINE and EMBASE on 14 November 2008. SELECTION CRITERIA: Randomised controlled trials (RCTs) of laser treatment of drusen in AMD in which laser treatment had been compared with no intervention or sham treatment. Two types of trials were included. Some trials studied one eye of each patient (unilateral studies); other studies recruited patients with bilateral drusen and randomised one eye to photocoagulation or control and the fellow eye to the other group. DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies and extracted data. We pooled data from unilateral and bilateral studies using a random-effects model. For the bilateral studies, we estimated the within-patient correlation coefficient from one study and assumed it was valid for the others. MAIN RESULTS: We found nine studies which randomised 2216 people: four unilateral trials, three bilateral trials and two trials that included both a unilateral and a bilateral study arm.Overall, the studies were of moderate quality. Only half of the trials reported adequate allocation sequence generation, allocation concealment and masking of visual acuity outcome assessors.Although two (of the nine) studies reported significant drusen disappearance at two years, photocoagulation did not appear to affect the development of CNV at two years follow up (nine studies, 1767 people followed up, odds ratio (OR) 1.04, 95% CI 0.71 to 1.51) or the loss of three or more lines of visual acuity (six studies, 1628 people followed up, OR 1.17, 95% CI 0.75 to 1.82). AUTHORS' CONCLUSIONS: The trials included in this review confirm the clinical observation that laser photocoagulation of drusen leads to their disappearance. However, there is no evidence that this subsequently results in a reduction in the risk of developing CNV, geographic atrophy or visual acuity loss

Diode laser treatment of posterior retinopathy of prematurity

AIMS—To study the efficacy of infrared diode laser for the treatment of posterior retinopathy of prematurity (ROP).
METHODS—48 eyes of 25 premature babies (mean birth weight 779 (SD 127.7) g; mean gestational age 25.5 (SD 1.47) weeks) with threshold ROP in zone I and posterior zone II were treated by the indirect infrared (810 nm) diode laser. Confluent burns were applied to the avascular retina. In 18 eyes, an additional row of laser burns was added posterior to the ridge.
RESULTS—Favourable anatomical results were noted in 41 eyes (85.4%). ROP stage 5 developed in two eyes, ROP stage 4A developed in four eyes, and ROP stage 4B in one eye. Three of the eyes with stage 4A eyes were successfully buckled; the fourth was not operated on and remained demarcated by laser scars. No complications were noted.
CONCLUSION—In this series, the diode laser was found to be a safe and effective treatment for posterior ROP.


Some simple models for continuous variate time series

A survey is given of recently developed mathematical models for continuous variate non-Gaussian time series. The emphasis is on marginally specific models with given correlation structure. Exponential, Gamma, Weibull, Laplace, Beta, and Mixed Exponential models are considered for the marginal distributions of the stationary time series. Most of the models are random coefficient, additive linear models. Some discussion of the meaning of autoregression and linearity is given, as well as suggestions for higher-order linear residual analysis for nonGaussian models. (Author)Prepared for: Office of Naval Research Arlington, VAhttp://archive.org/details/somesimplemodels00lewiApproved for public release; distribution is unlimited

Correlations Between the Morphology of Sonic Hedgehog Expression Domains and Embryonic Craniofacial Shape

Quantitative analysis of gene expression domains and investigation of relationships between gene expression and developmental and phenotypic outcomes are central to advancing our understanding of the genotype-phenotype map. Gene expression domains typically have smooth but irregular shapes lacking homologous landmarks, making it difficult to analyze shape variation with the tools of landmark-based geometric morphometrics. In addition, 3D image acquisition and processing introduce many artifacts that further exacerbate the problem. To overcome these difficulties, this paper presents a method that combines optical projection tomography scanning, a shape regularization technique and a landmark-free approach to quantify variation in the morphology of Sonic hedgehog expression domains in the frontonasal ectodermal zone (FEZ) of avians and investigate relationships with embryonic craniofacial shape. The model reveals axes in FEZ and embryonic-head morphospaces along which variation exhibits a sharp linear relationship at high statistical significance. The technique should be applicable to analyses of other 3D biological structures that can be modeled as smooth surfaces and have ill-defined shape