2020–2021 BCSC Basic and Clinical Science Course™
12 Retina and Vitreous
Part II: Disorders of the Retina and Vitreous
Chapter 16: Retinal Detachment and Predisposing Lesions
Lesions That Predispose Eyes to Retinal Detachment
Meridional Folds, Enclosed Ora Bays, and Peripheral Retinal Excavations
Meridional folds are folds of redundant retina, usually located superonasally. They are usually associated with dentate processes but may also extend posteriorly from ora bays. Occasionally, tears associated with PVD occur at the most posterior limit of the folds (see Chapter 1, Fig 1-3). Retinal tears can also occur at or near the posterior margins of enclosed ora bays, which are oval islands of pars plana epithelium located immediately posterior to the ora serrata and completely or almost completely surrounded by peripheral retina (Fig 16-9). Occasionally, tears may occur at the site of peripheral retinal excavations, which represent a mild form of lattice degeneration. The excavations may have firm vitreoretinal adhesions and are found adjacent to, or up to 4 disc diameters posterior to, the ora serrata. They are often aligned with meridional folds.
Figure 16-9 Color photograph of a gross eye specimen shows a meridional complex, consisting of an atypical and large dentate process (arrow) that is continuous with a ciliary process of the pars plicata and an area of enclosed pars plana and ora bay (asterisk). Slightly posterior to the complex is a small area in the same meridian that appears to be excavated but is in fact a cyst (small arrow).
(Used with permission from Foos RY, Silverstein RN, eds. System of Ocular Pathology. Vol. 3. Los Angeles: iPATH Press; 2004.)
Engstrom RE Jr, Glasgow BJ, Foos RY, Straatsma BR. Degenerative diseases of the peripheral retina. In: Tasman W, Jaeger EA, eds. Duane’s Clinical Ophthalmology on DVD-ROM. Vol 3. Philadelphia: Lippincott Williams & Wilkins; 2013:chap 26.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.