Apertures, graticules and filters:
Illuminates the largest area of fundus for the best possible general diagnosis through a dilated pupil.
Permits easier access through an undilated pupil and in peripheral examination. Particularly useful in paediatric examination.
Designed specifically for examination of the macular region of the fundus where a larger beam would create excessive pupillary reaction or patient discomfort.
Used primarily to determine retinal elevations and depressions but may also be used to assess anterior chamber depth.
Red Free with Fixation Cross:
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. The Fixation Cross to projects a graticule onto the retina for assessment of the degree and direction of eccentric fixation.
Used in conjunction with fluorescein dye for the detection and examination of corneal scars and abrasions.