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Apertures, graticules and filters:
Wide Angle:
Illuminates the largest area of fundus for the best possible general diagnosis through a dilated pupil.
Intermediate:
Permits easier access through an undilated pupil and in peripheral examination. Particularly useful in paediatric examination.
Macular:
Designed specifically for examination of the macular region of the fundus where
a larger beam would create excessive pupillary reaction or patient discomfort.
Slit:
Used primarily to determine retinal elevations and depressions but may also be used to assess anterior chamber depth.
Glaucoma:
Projects a graticule onto the retina to assess the optic cup/disc ratio as an aid to glaucoma diagnosis.
Fixation Cross:
Projects a graticule onto the retina for assessment of the degree and direction of eccentric fixation.
Red Free:
The red free filter is used to examine blood vessels in fine detail. By filtering out the red light, blood vessels are silhouetted black against a dark green background.
