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Coats’ White Ring: The Embellished and Spruced up Iron Remnant in the Cornea
 
Vishnu Teja Gonugunta
Department of of Cornea & Refractive Surgery Services, Aravind Eye Hospital, Madurai, Tamil Nadu, India


Corresponding Author
:
Vishnu Teja Gonugunta (MS)
Department of Cornea & Refractive Surgery Services
Aravind Eye Hospital, Madurai, Tamil Nadu, India
Email: vishnu.teja@aravind.org


Abstract

Coats’ white ring can be a common finding in the cornea following incomplete removal of the iron rust ring after ocular trauma with iron particles. Though the finding is common and innocuous, it’s etiology is rarely understood and commonly considered as a corneal opacity following an ocular injury and less recognised as a distinct entity. It can be diagnosed from the history and the typical appearance as a ring of discrete white dots in the subepithelial layers with intact epithelium. Patients are asymptomatic and treatment is not required.

Introduction
A 34-year-old male patient, welder by occupation came for his routine eye check-up. He had past history of episodes of iron metal chips flown into both of his eyes while working without protective eye wear few years back. Examination of his right eye revealed macular corneal opacity, whereas his left eye revealed Coats’ white ring of 1.5 mm diameter near the temporal limbus (Figure 1A and 1B). Coats’ white ring is a form of iron deposition in the cornea which is often circular or oval in shape and was first described by George Coats. It is located within the Bowman’s membrane or the anterior stroma, and is composed of a complete or incomplete ring of discrete white dots. The overlying epithelium is smooth and intact. The lesion(s) are associated with previous metallic corneal foreign bodies.1,2 It is usually seen in the area of incompletely removed rust ring in the cornea. Calcium was thought to be the cause of the lesion as an occupational injury in limestone workers.3 But the lesion doesn’t contain calcium or lipid as it was thought before. Histochemical analysis confirmed the presence of iron within the lesion.4 Patients with Coats ring are asymptomatic. These incidental findings don’t require any treatment.



References
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  2. Stallard HB. White Rings In The Cornea. Br J Ophthalmol. 1934;18:452-453
  3. Miller EM. Genesis of white rings of the cornea. Am J Ophthalmol.1966 ;61:904-7.
  4. Nevins RC, Davis WH, Elliott JH. Coats' white ring of the cornea—unsettled metal fettle. Arch ophthalmol. 1968;80:145–146.