Ascher Ring
Key Points at a Glance
Section titled “Key Points at a Glance”1. What is Ascher ring?
Section titled “1. What is Ascher ring?”Ascher ring is a bilateral, symmetric annular opacity that appears in the corneal stroma of the mid-periphery 1). In 1964, Dr. Ascher of Germany first reported a bilateral 7 mm anterior stromal ring in a 39-year-old patient with a history of unilateral iritis.
Only a few cases have been reported worldwide, making it an extremely rare finding. In 1998, Melles et al. reported bilateral mid-peripheral annular opacities in a healthy 25-year-old patient and reviewed six previously reported cases 1). The disease concept was reaffirmed in a 2001 case report by Rohrbach et al. 2) and a 2021 case report and literature review by Megalla et al. 3).
It is asymptomatic and non-progressive, with no associated hereditary patterns or systemic diseases 1,3). It is treated as a diagnosis of exclusion and requires no treatment.
2. Main symptoms and clinical findings
Section titled “2. Main symptoms and clinical findings”Subjective symptoms
Section titled “Subjective symptoms”Ascher ring is asymptomatic and is discovered incidentally during slit-lamp examination.
Clinical findings (findings confirmed by the physician)
Section titled “Clinical findings (findings confirmed by the physician)”- Annular opacity: A continuous, gray-white, granular annular stromal opacity 7–8 mm in diameter appearing in the mid-periphery of the cornea. The width is less than 0.5 mm and thin 1).
- Depth: Located at various depths within the stroma. The cross-section is V-shaped, widest near Descemet’s membrane 1). The anterior apex is slightly displaced toward the central cornea.
- Bilateral and symmetric: All reported cases have been bilateral and symmetric 1,3).
- Corneal transparency: The central and peripheral cornea outside the annular opacity remains clear.
3. Etiology and Differential Diagnosis
Section titled “3. Etiology and Differential Diagnosis”Etiology
Section titled “Etiology”The etiology of Archer’s ring has not been fully elucidated.
Initially, it was thought to be the result of an immune reaction similar to the Wessely immune ring, because some patients had a history of unilateral iritis or marginal infiltration. However, recent evidence suggests it may be an extracellular deposit along a centripetal gradient.
Differential Diagnosis
Section titled “Differential Diagnosis”The following conditions should be differentiated as annular opacities of the corneal stroma:
- Wessely immune ring: An annular infiltration in the corneal stroma caused by antigen-antibody reaction, seen in infectious keratitis and after corneal transplantation. It differs by the presence of inflammatory signs.
- Annular infiltration in infectious keratitis: Seen in fungal and Acanthamoeba keratitis, accompanied by inflammatory symptoms such as pain and redness.
- Corneal dystrophy: Hereditary corneal opacity, differentiated by family history and progressive course.
- LASIK flap edge: A similar annular finding may be seen in the cornea after LASIK surgery, but it can be easily differentiated by the presence or absence of surgical history.
The Wessely immune ring is an annular infiltration formed by antigen-antibody reaction, appearing with inflammatory signs in infectious keratitis or after corneal transplantation. In contrast, Archer’s ring is an asymptomatic annular opacity without inflammatory signs, thought to be a deposit of extracellular material.
4. Diagnosis
Section titled “4. Diagnosis”Archer’s ring is a diagnosis of exclusion, made after ruling out other causes of corneal stromal opacity.
Examination
Section titled “Examination”- Slit-lamp examination: Confirms bilateral, symmetric ring-shaped opacity in the mid-peripheral stroma.
- Anterior segment optical coherence tomography (AS-OCT): Visualizes the depth and extent of corneal stromal opacity.
- Confocal microscopy: Depicts reflective extracellular deposits at the cellular level.
Diagnostic clues include transparency of the central and peripheral cornea, absence of inflammatory signs, and bilateral symmetric involvement.
It is an extremely rare finding with only a few reported cases worldwide. Since the first report in 1964, only about 10 cases have been documented in the literature.
5. Management and Prognosis
Section titled “5. Management and Prognosis”Archer ring does not affect visual function and does not require treatment. It is non-progressive, so management consists only of observation.
The prognosis is excellent, with no reports of visual impairment.
Treatment is unnecessary. Archer ring is an asymptomatic finding that does not affect visual function and is non-progressive. Management consists only of observation, and the prognosis is excellent1,3).
6. References
Section titled “6. References”- Melles GR, de Séra JP, Eggink CA, Cruysberg JR, Binder PS. Bilateral, anterior stromal ring opacity of the cornea. Br J Ophthalmol. 1998;82(5):522-525.
- Rohrbach JM, Kleiser N, Kaufmann-Fechner J, Lisch W. Corneal ring opacity (Ascher ring) - a case report. Klin Monbl Augenheilkd. 2001;218(4):276-278.
- Megalla M, Li E, Branden P, Chow J. Bilateral idiopathic corneal opacity: a report of Ascher ring and a review of the literature. Am J Ophthalmol Case Rep. 2021;23:101176.