Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Ansari-Shahrezaei, S; Stur, M.
Magnification characteristic of a +90-diopter double-aspheric fundus examination lens.
Invest Ophthalmol Vis Sci. 2002; 43(6):1817-1819
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- Führende Autor*innen der Med Uni Graz
- Ansari Shahrezaei Siamak
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- Abstract:
- To investigate the magnification characteristic of the +90-D double-aspheric fundus examination lens for biomicroscopic measurement of the optic disc. A calibrated Gullstrand-type model eye adjusted for axial ametropia between -12.5 and +12.6 D was used to measure the change in magnification of the system with refractive error and variation in fundus lens position. A correction factor p (in degrees per millimeter) at different axial ametropias was also calculated. The total change in magnification of the system from myopia to hyperopia was -15.1% to +13.7%. When the fundus lens position was altered with respect to the model eye by +/-2 mm under myopic conditions, the change in magnification of the system was -4.8% to +8.1%. In the hyperopic condition the change was -4.8% to +6.0%. The fundus lens exhibited a linear relationship between p and the degree of ametropia of the model eye and a constant relationship between p and ametropia of -5 to +5 D. Axial ametropia has a significant effect on biomicroscopic measurement of the optic disc with the +90-D lens. Therefore, a correction factor (p) was calculated that can be used in calculations for determining true optic disc size. These findings may be important for improving clinical disc biometry.
- Find related publications in this database (using NLM MeSH Indexing)
- Fundus Oculi -
- Humans -
- Lenses -
- Models, Anatomic -
- Optic Disk - anatomy & histology
- Optics and Photonics -