90 D Volk fundus lens.

The 90 D lens is used in conjunction with a slit lamp biomicroscope to provide a stereoscopic indirect view of the ocular fundus. The clinical picture is an indirect view of the posterior pole and as far anterior as the equator. Being hand-held, it requires some practice to maintain alignment but does not require contact with the globe. Table 1 summarizes the clinical advantages and disadvantages of the 90 D lens.