PubMed · 7093789
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K E Schirmer. 1982. [Gullstrand's fundus microscopy - present developments].. https://pubmed.ncbi.nlm.nih.gov/7093789/
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In a long-term study of 1270 patients with at least one of the findings, open-angle glaucoma, disc haemorrhages or retinal vein occlusions, disc haemorrhages were witnessed in approximately 20% of the cases with open-angle glaucoma, and were a precursor of glaucomatous disc changes and associated visual field defects. Disc haemorrhages also preceded a rising intraocular pressure (IOP) in the destructive process among open-angle glaucoma cases. Similar glaucomatous development appears among cases independent of IOP or detection of exfoliation syndrome. Retinal vein occlusions and disc haemorrhages behave similarly with respect to glaucoma. The large number of transgressions is an argument against dividing glaucoma into different types. These findings support a vascular genesis to open-angle glaucoma, presented in earlier epidemiological studies.
PURPOSE: To investigate the magnification characteristic of the +90-D double-aspheric fundus examination lens for biomicroscopic measurement of the optic disc. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.