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D Robert Iskander; The clinical utility of the Eye Surface Profiler. Invest. Ophthalmol. Vis. Sci. 2013;54(15):533.
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To evaluate the effectiveness of the Eye Surface Profiler in measuring the topography of the anterior eye surface.
Eye Surface Profiler (ESP) is a newly developed cornea and sclera topographer that can measure up to 20mm of the anterior surface of the eye. It is an evolution of a wide field height eye topographer [Jongsma et al. OVS; 1998]. Three tasks were set. Since ESP requires instillation of fluorescein, the optimal combination of the fluorescein strips and the eye physiological solution that results in the best quality of recorded images was assessed. Further, the repeatability of the instrument in measuring artificial and real eye surfaces was studied. Finally, the new topographer was tested in clinical settings against traditional Placido disk topographer (E300, Medmont) for a range of normal, astigmatic, and highly aberrated eyes (post corneal grafts).
The best results in terms of highly resolved ESP images have been achieved with BIO GLO sterile strips (1 mg fluorescein sodium) with Hial eye drops (0.4 mg/ml hialuronian sodium). For artificial surfaces, the repeatability of instrument in a dynamic case, when operator manually focused the instrument, was very high while the accuracy of the instrument in terms of the RMS error was less than 10um but depended on the instrument-surface distance. The working distance was estimated at +/-250um from the best focal plane. For real eyes, the coverage area was routinely greater than 16mm and often reached up to 20mm diameter. Single instillation of fluorescein allowed acquisition from 3 to 20 measurements (taken in less than 30 second intervals). Repeatability, evaluated with refractive spherical component over an 8 mm corneal diameter, was high (differences less than 0.125 D). When tested against the E300 topographer, ESP showed excellent repeatability for spherical power (in an 8 mm corneal diameter) but seemed to overestimate the astigmatic component, which seemed to depend on the instrument’s working distance. For highly aberrated eyes, in situations where E300 could not perform a valid measurement, the ESP was still performing well.
ESP has high potential clinical utility. It could substitute the currently used videokeratoscopes and provide a new diagnostic quality in those applications in which information on corneoscleral topography is of essence.
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