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Crocodile Shagreen corneal dystrophy

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Title: Crocodile Shagreen corneal dystrophy
Author (s): Tanner Ferguson, MSIV, University of South Dakota Sanford School of Medicine, Jeff Pettey, MD, Moran Eye Center, University of Utah
Photographer: James Gilman
Date: 07/31/17
Keywords/Main Subjects: Cornea, corneal mosaic dystrophy, crocodile shagreen
Diagnosis: Crocodile shagreen corneal degeneration
Images:

Image 1: On this anterior view of the cornea, the polygonal pattern of opacities with well demarcated intervening clear spaces is visualized.

Image 2: This photo enables the viewer to appreciate the resemblance to crocodile skin and the distinct appearance of the degenerative disorder.

Image 3: In this photo, the intervening clear spaces amongst the opacities are well visualized and the “scaly” appearance is appreciated. Furthermore, the image permits the viewer to appreciate that it likely involves the posterior portion of the corneal stroma.

Summary of the Case:
A 67 year-old female with past medical history significant for Type II diabetes mellitus presented with blurry vision of 6 months onset that is worse at distance. She also complained of glare at night and difficulty with oncoming headlights while driving. Her BCVA is 20/50 in her right eye and 20/60 in her left eye; her BAT is 20/70 and 20/80 in her right and left eye. On exam, her cataracts were graded as 2+ NS (nuclear sclerotic) and 2+ cortical spoking OU. Her cornea also demonstrated a polygonal pattern of opacities in the posterior stroma with clear intervening spaces, resembling a “crocodile skin.” The clinician did not feel her visual complaints were related to the corneal findings revealed on exam and the findings were documented as crocodile shagreen.

Crocodile shagreen background
Crocodile shagreen is a clinical finding that was initially described in the 1920’s and named by Vogt in 1930.1 The disorder is characterized by a grayish, polygonal pattern of opacities with intervening clear zones across the central cornea that resembles crocodile skin.1,2 Although it is classically found in the central visual axis in the cornea, patients are often asymptomatic. It is a benign, degenerative disorder and is commonly found in the elderly population.3

The pathogenesis of the finding remains unknown. It is typically found in the posterior two-thirds of the corneal stroma. Studies with histopathology have reported the presence of clusters of vacuoles and a sawtooth-like configuration of the lamellar collagen in the corneal stroma3-5. Krachmer et al.5 proposed that this irregular collagenous arrangement in the posterior stroma observed on transmission electron microscopy is thought to contribute to the clinical appearance of the finding under the slit lamp. Furthermore, this report suggested that vision is unaffected because the anterior corneal surface is regular. Although the pathogenesis remains unclear, studies have suggested that the presence of vacuoles amongst degenerating keratinocytes is evidence of a degenerative process.2

Central cloudy dystrophy of François (CCDF) is a disease entity with a similar clinical appearance. However, CCDF is distinguished from crocodile shagreen by its autosomal dominant inheritance pattern and may be seen in younger patients.6 The diagnosis of CCDF may be more appropriate if numerous family members present with similar corneal mosaic patterns.2

Currently, the significance of this finding remains unclear. Because it is an incidental and benign finding, it is likely underreported. Although it has been reported with other ocular disease entities in isolated cases, there is no clear association5-7. Future studies are needed to contribute to the understanding and significance of this disorder.

Faculty Approval by: Jeff Pettey, MD
References

  1. Vogt A. Lehrbuch Und Atlas Der Spaltlampenmikroskopie Des Lebenden Auges: Mit Anleitung Zur Technik Und Methodik Der Untersuchung. Technik Und Methodik. …. 1930.
  2. Belliveau MJ, Brownstein S, Agapitos P, Font RL. Ultrastructural Features of Posterior Crocodile Shagreen of the Cornea. Survey of Ophthalmology. 2009;54(5):569-575. doi:10.1016/j.survophthal.2009.02.022.
  3. Meyer JC, Quantock AJ, Kincaid MC, Thonar EJMA, Hageman GS, Assil KK. Characterization of a Central Corneal Cloudiness Sharing Features of Posterior Crocodile Shagreen and Central Cloudy Dystrophy of Francois. Cornea. 1996;15(4):347.
  4. Karp CL, Scott IU, Green WR, Chang TS. Central cloudy corneal dystrophy of François: a clinicopathologic study. Archives of …. 1997.
  5. Krachmer JH, Dubord PJ, Rodrigues MM, Mannis MJ. Corneal Posterior Crocodile Shagreen and Polymorphic Amyloid Degeneration: A Histopathologic Study. Arch Ophthalmol. 1983;101(1):54-59. doi:10.1001/archopht.1983.01040010056008.
  6. Bramsen T, Ehlers N, Baggesen LH. CENTRAL CLOUDY CORNEAL DYSTROPHY OF FRANÇOIS. Acta Ophthalmologica. 1976;54(2):221-226. doi:10.1111/j.1755-3768.1976.tb00435.x.
  7. Woodward M, Randleman JB, Larson PM. In Vivo Confocal Microscopy of Polymorphic Amyloid Degeneration and Posterior Crocodile Shagreen. Cornea. 2007;26(1):98-101. doi:10.1097/01.ico.0000240103.47508.c4.

Identifier: Moran_CORE_24263
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