3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea.

Capable of three-dimensional imaging of the cornea with micrometer-scale resolution, spectral domain-optical coherence tomography (SDOCT) offers potential advantages over Placido ring and Scheimpflug photography based systems for accurate extraction of quantitative keratometric parameters. In this work, an SDOCT scanning protocol and motion correction algorithm were implemented to minimize the effects of patient motion during data acquisition. Procedures are described for correction of image data artifacts resulting from 3D refraction of SDOCT light in the cornea and from non-idealities of the scanning system geometry performed as a pre-requisite for accurate parameter extraction. Zernike polynomial 3D reconstruction and a recursive half searching algorithm (RHSA) were implemented to extract clinical keratometric parameters including anterior and posterior radii of curvature, central cornea optical power, central corneal thickness, and thickness maps of the cornea. Accuracy and repeatability of the extracted parameters obtained using a commercial 859nm SDOCT retinal imaging system with a corneal adapter were assessed using a rigid gas permeable (RGP) contact lens as a phantom target. Extraction of these parameters was performed in vivo in 3 patients and compared to commercial Placido topography and Scheimpflug photography systems. The repeatability of SDOCT central corneal power measured in vivo was 0.18 Diopters, and the difference observed between the systems averaged 0.1 Diopters between SDOCT and Scheimpflug photography, and 0.6 Diopters between SDOCT and Placido topography.

Through the Lenses of Q’eqchi Maya: (Re)Framing the Story of Development in a Guatemalan Indigenous Community Through Participant-Created Photographs

The question of evaluations of development projects has been widely debated within the field of international development, with scholars and development practitioners calling for increased community-driven evaluations. However, there has been a paucity of research in community-led project evaluations, and a largely absent investigation utilizing visual anthropology/sociology methodologies. This paper seeks to shift this power by giving voice to the intended beneficiaries of an eco-tourism project in a rural indigenous Guatemala village. Through photographs taken by community members and corresponding interviews, this paper shows the way in which community members have and continue to reframe the idea of development in their village. Specifically, my analysis reveals how residents see changing forms of access, how they reframe ideas of beauty and modernization, and how they reframe their relationship to the land through Western conservation and private property ideals. This research thus provides an alternative narrative to the Western NGO’s evaluations and knowledge production, especially in respect to development and indigenous knowledge. By showing how community members are reframing the story of development, this paper demonstrates the usefulness of using participatory documentary photography in community-led evaluations, and helps balance the playing field by providing a much-needed alternative narrative of project evaluation.