Also known as spheroidal degeneration, Labrador keratopathy, or climatic droplet keratopathy, actinic keratopathy is characterized by aggregates of translucent, golden-brown spheroidal deposits in the interpalpebral superficial cornea (Fig 6-11A). The condition is generally bilateral and is more common in males. Smaller spheroidal deposits may mimic calcific band keratopathy; this phenomenon has been described as “actinic” band keratopathy.
The etiology is controversial, but cumulative evidence suggests that the deposits develop from ultraviolet (UV) radiation–induced alteration of preexisting structural connective tissue components or from the synthesis of abnormal extracellular material at the limbal conjunctiva. This abnormal material progressively diffuses into the superficial cornea, precipitates over a prolonged period, and may be further modified by UV light. Factors involved in the pathogenesis of actinic keratopathy include sun exposure and dry climate, as the condition is more prevalent in dry equatorial regions.
Figure 6-11 Actinic keratopathy (also called spheroidal degeneration or climatic droplet keratopathy). A, Gross appearance of a corneal button showing golden-brown superficial opacities. The air bubbles are artifacts. B, Histology shows irregular, pale, basophilic globules (arrows) extending from the epithelium into the superficial stroma.
(Courtesy of Hans E. Grossniklaus, MD.)
Histologic examination reveals irregular, basophilic globules deep to the epithelium in the region of Bowman layer and the anterior stroma (Fig 6-11B). Analogous to the actinic degeneration of collagen in pingueculae and pterygia, the deposits stain black with special stains for elastin, such as Verhoeff–van Gieson.
Serra HM, Holopainen JM, Beuerman R, Kaarniranta K, Suarez MF, Urrets-Zavaliá JA. Climatic droplet keratopathy: an old disease in new clothes. Acta Ophthalmol. 2015;93(6):496–504.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.