Anatomy

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Slide 100

The 1.5-mm-diameter fovea corresponds to the retinal avascular zone of fluorescein angiography.

Histologically it is characterized by thinning of the outer nuclear layer and absence of the other parenchymal layer

Slide 101

thinnest part of area of the retina (0.25 mm), containing only cone photoreceptor

Slide 102

blood supply from two sources: the choriocapillaris which supplies the outer third of the retina, and branches of the central retinal artery, which supply the inner two-thirds .

The fovea is supplied entirely by the choriocapillaris and is susceptible to irreparable damage when the retina is detached.

Slide 103

The retinal blood vessels have a nonfenestrated endothelium, which forms the inner blood-retinal barrier.

The endothelium of choroidal vessels is fenestrated. The outer blood-retinal barrier lies at the level of the retinal pigment epithelium.

Slide 104

The Vitreous

Slide 105

clear, avascular, gelatinous body that comprises two-thirds of the volume and weight of the eye.

The outer surface of the vitreous—the hyaloid membrane—is normally in contact with the following structures: the posterior lens capsule, the zonular fibers, the pars plana epithelium, the retina, and the optic nerve head.

The base of the vitreous maintains a firm attachment throughout life to the pars plana epithelium and the retina immediately behind the ora serrata. The attachment to the lens capsule and the optic nerve head is firm in early life but soon disappears.

Slide 106

99% water.

The remaining 1% includes two components, collagen and hyaluronic acid

Slide 107

The External Anatomic Landmarks

Slide 108

Accurate localization of the position of internal structures with reference to the external surface of the globe is important in many surgical procedures.

Externally, the ora serrata is situated approximately 5.5 mm from the limbus on the medial side and 7 mm on the temporal side of the globe. This corresponds to the level of insertion of the rectus muscles.

Slide 109