BIO Home Optics of BIO BIO Preparation Patient Preparation Continuing Education Exam
The View of the Anterior Fundus
Once skills for examining the posterior fundus have been mastered, including the necessary ability to scan across the fundus, you can turn your attention to the anterior fundus.
There are techniques that permit you to see the anterior fundus more easily.
The first step to seeing the anterior fundus is for the patient to move the eye far into the direction the examiner wants to see, while the examiner moves just as far from that direction and maintains a view of the fundus.
Tilt your head to the long axis of the patient's pupil. As the patient looks away 
from you, the pupil becomes elliptical. If no adjustments were made, it would be impossible to fit the visual axes of the ophthalmoscope and the light into the pupil at the same time due to the shorter axis of the ellipse. By tilting your head to the long axis of the patient's pupil, one eyepiece and the light source could be used to see the fundus monocularly. With appropriate manipulation, the examiner can see more peripherally in the anterior fundus.
Tilt the condensing lens so that the two Purkinje images from the lens are oriented along the long axis of the elliptical pupil. This will compensate for the induced oblique astigmatism from the peripheral optics of the eye.
Since the ophthalmoscope light enters the eye from higher in the housing than the examiner's visual axes, it is necessary to move as far from the patient as possible when examining the anterior fundus. Otherwise, the examiner is cut off from a view of the anterior fundus by the iris. This advice is also useful when examining the posterior fundus through a small pupil.
Use the prismatic effect of the high plus condensing lens to get out further in the anterior fundus. A slight vertical movement of the lens will allow a more anterior view. Too much movement will cause the loss of the image as the light moves onto the iris.
Landmarks in Fundus Examination 
Vortex-vein ampulla. When you begin the examination of the right fundus in the superior nasal area, the equatorial landmark, a vortex-vein ampulla, should be evident immediately.
This structure is significant for orientation purposes since its posterior border demarcates the equator of the globe. Its striking appearance also serves an orienting function.
Nasal and temporal long ciliary nerve. As you proceed to the nasal quadrant of the right eye (patient looking toward own left ear, examiner's head stationed at right ear of patient, right hand holding the condensing lens, right middle finger retracting lower lid, left thumb retracting upper lid), a yellow-to-orange linear structure with variably pigmented borders is observed; this is the nasal long ciliary nerve. It runs a course anteriorly along the horizontal meridian through the choroid. As landmarks, the nasal long ciliary nerve, with its companion temporal long ciliary nerve, separate superior from inferior fundus.
Short ciliary nerves. When you move to an 11 o'clock position with respect to the patient's head and direct the patient's gaze toward the left shoulder, you should observe the short ciliary nerves in the right inferior nasal fundus. These fine, lightly colored branching structures are located in the choroid on either side of both vertical meridia, for a total of four per eye..
Ora serrata. The ora serrata is the most anterior extent (peripheral termination) of 
the sensory retina. It appears more scalloped on the nasal half of the fundus than on the temporal half. Orange tissue beyond the sensory retina represents ciliary epithelium (pars plana).
The optic disc, equator, and ora serrata are often used as landmarks to localize lesions. distance is usually measured in disc diameters (DD). For example, a retinal tear could be noted as 1 DD from the ora serrata at 5 o'clock.
Welch Allyn Global
