Optimizing OCT acquisition parameters for assessments of vitreous haze for application in uveitis.

Detection and evaluation of inflammatory activity in uveitis is essential to the management of the condition, and yet continues to be largely dependent on subjective clinical measures. Optical coherence tomography (OCT) measurement of vitreous activity is an alternative to clinical vitreous haze scoring and has passed a number of early validation studies. In this study we aimed to evaluate the impact of 'operator factors' on the variability of the technique as part of the validation process, and to help evaluate its suitability for 'real world' use. Vitreous haze index was calculated as a ratio between the reflectivity of the vitreous and of the outer retina in each scan. Different scanning conditions were tested and their effect on the measurement is reported. Our results show that the 'quantitative imaging' technique of OCT-measured vitreous activity had good reliability in normal subjects under a range of 'real world' conditions, such as when the operator changes the averaging value. The technique was however vulnerable to highly inaccurate focussing or abnormal downward displacement of the image. OCT-based quantification of vitreous activity is a promising alternative to current subjective clinical estimates, with sufficient 'tolerance' to be used in routine clinical practice as well as clinical trials.

Reproductive strategies in the freshwater sphaeriid clam,Musculium partumeium (say), from a permanent and a temporary pond.

Reproduction was studied in two populations ofMusculium partumeium from temporary and permanent ponds. Adults of the single annual generation from the ephemeral pond have an annual selection ratio of 25:1 with 37.03 µgC per newborn, and an intrinsic rate of increase (r) of 0.0084 day-1. Fall-born adults from the permanent pond have an annual selection ratio of 38:1, 21.82 µgC per newborn and anr of 0.0115 day-1; springborn adults have an annual selection ratio of 136:1 (107:1 for their contribution to fall birth and 29:1 for the spring birth period) with newborns of 24.21 µgC and anr of 0.0304. The trade off between quantity and quality of young is discussed in terms of adaptive strategies.