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D. Link, B. U. Seifert, W. Vilser; Preliminary Findings on in vivo Fundus Pattern Projection Using the Universal Retina Camera. Invest. Ophthalmol. Vis. Sci. 2008;49(13):898. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The Universal Retina Camera (URC) was used to demonstrate an adaptive spatial and temporal pattern projection onto the human retina.
The apparatus used was the URC, which is a fundus-camera based setup as optical framework with two integrated spatial light modulators (SLM). Appropriate SLM positions and the control of each pixel by VGA interfaces realise a programmable optical path with the objective to have a spatial and temporal two-plane modulation. Thus, it is possible to control the light entrance into the eye (anatomic pupil plane = first plane) and to project patterns onto the retina (second plane) at the same time. The cross-sectional beam shape in the anatomic pupil plane was set to annular shape to assure the separation of illumination and imaging path. Local and temporal modulation of the fundus illumination for both static and dynamic tests was realised. A therefore required SLM was a light-transmissive micro display adapted to a 45 degrees field of view. In order to get maximum vessel contrast in the fundus images green incoherent light was used. In vivo examinations were performed on healthy subjects with mydriatic eyes.
The results of preinvestigations and tests using an artificial eye could be verified in healthy subjects. The effects of a two-plane modulation were demonstrated and confirmed in vivo. Within a field of 45 degrees the human fundus can be illuminated with arbitrary patterns. In static mode different illumination patterns like checkerboards, slits, and spots were projected onto the fundus and imaged simultaneously. In stimulation mode dynamic test patterns can be applied with frequencies of 30 Hz, 15 Hz, and 7.5 Hz. Typical values for the contrast between illuminated and blocked areas as measured from captured images are in the range from 6:1 (on the macula) to 15:1 (outside the macula).
Preliminary results are presented using the URC for projecting arbitrary patterns onto the living fundus. The single images and live image sequences are captured to demonstrate the modulation effects on the human fundus. The used setup enables the application of stimulation paradigms as well as methods for fundus measuring in the area of 45 degrees. A variety of possible applications incorporated in one single device makes the URC a promising tool for complex functional analysis of the human fundus. Further research and optimisation is needed to improve performance and handling of the URC.
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