Optometry Research Today is a free monthly online journal that collates and summarizes the latest research about Optometry, including details on myopia, optometric practice, therapy.

The effect of digital measurement software on photodynamic therapy.

Ansari-Shahrezaei S, Ergun E, Stur M

Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria, siamak.ansari-shahrezaei@meduniwien.ac.at.

BACKGROUND: To investigate the effect of refraction-corrected digital measurement software on photodynamic therapy (PDT) treatment spot size. METHODS: Experimental study using a calibrated Gullstrand-type model eye. The axial length of the model eye was set to different values, ranging from 20 to 31 mm, and the PDT treatment spot sizes obtained from refraction-corrected digital measurement software and manual measurement with a fixed-magnification factor, as well as four different indirect contact laser lenses, were calculated and compared for a treatment spot with a diameter of 4 mm. RESULTS: The maximum deviation from the treating laser spot was +39.6% under myopic and +17.4% under hyperopic conditions when the refraction-corrected digital measurement software was used. The maximum deviation was +14.2% under myopic and +13.3% under hyperopic conditions when the manual measurement with the fixed-magnification factor was used. CONCLUSIONS: The use of refraction-corrected digital measurement software produces a larger deviation from treating laser spot than the use of manual measurement with a fixed-magnification factor. Therefore, refraction-corrected digital measurement software might not be suitable for calculating the recommended PDT treatment spot size in eyes with high refractive errors.

Published 23 February 2006 in Graefes Arch Clin Exp Ophthalmol, 244(2): 137-42.
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