A Wessely immune ring in the cornea represents which process?

A localized immune reaction within the corneal stroma The Wessely ring is a localized immune reaction in the corneal stroma and marks significant antigenic stimulation, making it a clue to the nature of the infection.

Lipid deposition at the corneal periphery

Endothelial decompensation with stromal edema

Epithelial downgrowth along a wound track

Which mechanism produces the annular infiltrate of a Wessely immune ring?

Antigen and antibody precipitating at a zone of equivalence Antigen released centrally diffuses outward while antibody diffuses in from the limbal vessels; where they meet they precipitate and attract neutrophils and complement.

Neutrophil migration along the corneal nerves

Direct circular spread of the organism

Contraction of an established stromal scar

The clear zone between the central focus and a Wessely ring corresponds to what?

A region of antigen excess Closer to the central focus antigen is in excess, so no precipitate forms there and the cornea between the focus and the ring stays relatively clear.

A zone where complement has been depleted

An area of resolved stromal edema

A band of absent corneal nerves

A Wessely immune ring at the slit lamp usually measures what diameter?

2 to 4 mm The ring is a gray-white circular stromal band usually 2 to 4 mm across, concentric with a central focus of infection or foreign material.

Which feature separates a Wessely immune ring from the ring ulcer of marginal keratitis?

It lies in central or paracentral stroma, not near the limbus A staphylococcal or marginal ring ulcer sits near the limbus, whereas the Wessely ring lies in central or paracentral stroma with a clear zone inside it.

It stains densely with fluorescein across its full width

It is confined entirely to the corneal epithelium

It contains iron rather than inflammatory cells

Which ring-shaped corneal finding forms around an old foreign body and contains iron?

Coats white ring The Coats white ring is a small, white, iron-containing ring around an old foreign body; the Fleischer ring encircles a keratoconus cone and the Kayser-Fleischer ring is peripheral copper in Wilson disease.

In herpes simplex stromal keratitis, what does an immune ring imply about treatment?

Immune suppression is needed alongside antiviral cover In herpetic disease the ring signals necrotizing stromal keratitis, which requires immune suppression together with antiviral cover.

Antiviral monotherapy will be sufficient

Topical antibiotics should replace antiviral therapy

Treatment can be deferred until the scar settles

What is characteristic of the ring infiltrate of Acanthamoeba keratitis?

It appears late in the course, in a very painful eye In Acanthamoeba keratitis the ring develops later in the disease course, often suggesting a delay in diagnosis, and the keratitis is typically very painful.

It appears within the first day of symptoms

It is painless and resolves without any treatment

It is confined to the limbal vascular arcades

Which drug classes are used for the prolonged treatment of Acanthamoeba keratitis?

Biguanides and diamidines Acanthamoeba keratitis requires prolonged therapy with biguanides and diamidines, in contrast to the antivirals or antibacterials used for other causes of an immune ring.

Fluoroquinolones and aminoglycosides

Nucleoside antivirals and interferons

Which corneal outcome commonly follows a Wessely immune ring?

A residual stromal scar A Wessely ring often leaves a stromal scar, and the visual outcome depends on the cause, the speed of diagnosis and the response to treatment.

Return to a completely clear cornea

Permanent corneal neovascularisation

Wessely Ring: Corneal Immune Ring Explained

In a cornea with stromal keratitis, a ring of gray-white infiltrate may form around a central focus, with a clear zone in between.

This is a Wessely immune ring, and it represents a localized immune reaction in the corneal stroma.

It is a clue to the nature of the infection, and it is a sign of significant antigenic stimulation.

How it forms

When antigen is released in the center of the stroma, as from a replicating virus or an organism, antibodies diffuse in from the limbal vessels.

The two meet at a zone of equivalence, where they precipitate and attract neutrophils and complement.

The result is an annular band of inflammation and stromal opacity, concentric with the original focus.

A clear zone between the center and the ring corresponds to the region of antigen excess.

The ring was described by Karl Wessely in 1911 in experimental work on rabbit corneas.

When you see it

Herpes simplex stromal keratitis, in which it occurs in necrotizing disease
Fungal keratitis, where it may appear around a satellite lesion
Acanthamoeba keratitis, in which a ring-shaped infiltrate is a well-known late sign (see Acanthamoeba ring infiltrate)
Bacterial keratitis, particularly Pseudomonas, with ring ulcer
Reaction to foreign material, for example, after a retained foreign body or a corneal injection
Vaccinia and some other viral infections

Test your knowledge 10 questions from this article

How it differs from other rings

A ring ulcer of staphylococcal or marginal keratitis lies near the limbus.

The Wessely ring lies in the stroma, within the central or paracentral cornea, with a clear zone between the center and the ring.

A Fleischer ring is an iron line around a keratoconus cone, and a Kayser-Fleischer ring is copper deposition at the periphery in Wilson disease.

The Coats white ring is a small, white, iron-containing ring that forms around an old foreign body.

What it means clinically

A ring signals active, intense stromal inflammation, and it often means a more severe or longer-standing disease.

In Acanthamoeba keratitis it may suggest delay in diagnosis.

In herpetic stromal keratitis, it is a sign of necrotizing disease that needs immune suppression along with antiviral cover (see herpetic stromal keratitis).

Evaluation

Detailed history of contact lens wear, trauma, herpes, and previous treatment
Slit-lamp assessment of the ring, central focus, epithelial defect, and endothelial involvement
Corneal scraping for smears, cultures, and PCR, including for Acanthamoeba when relevant (see corneal ulcer culture technique)
Confocal microscopy, when available, to look for cysts or hyphae

Treatment

Treatment follows the cause.

Antiviral therapy and corticosteroids are used for herpetic disease, with antimicrobial therapy for bacterial or fungal infection.

Acanthamoeba requires prolonged therapy with biguanides and diamidines.

Steroids must be used with great caution unless the cause is clear.

Clinical eye photograph illustrating Wessely Immune Ring

Recognizing the ring at the slit lamp

The ring is a gray-white, circular band in the stroma, usually 2 to 4 mm in diameter, concentric with a central focus of infection or foreign material. Between the center and the ring there is a zone of relatively clear cornea. The overlying epithelium may be intact or ulcerated, and the anterior chamber often shows cells, flare, and sometimes a hypopyon. Look for stromal edema, new vessels, and thinning, which signal severe disease.

What the ring suggests about the cause

In herpetic stromal keratitis, a ring can accompany necrotizing disease and often follows repeated attacks. In Acanthamoeba keratitis, the ring appears later in the course, and the disease is typically very painful. In fungal keratitis, rings are associated with deep stromal infiltrates and satellite lesions. A ring around a foreign body suggests a reaction to material in the stroma. No single feature is diagnostic, so scraping and culture, PCR, and sometimes biopsy are needed.

Practical management points

Take cultures before treatment where possible, and avoid steroids until infection has been excluded or controlled. Monitor closely for thinning and perforation, and be prepared to arrange transplantation if the cornea melts. Educate the patient about the importance of regular drops, follow-up, and avoiding contact lens use until the eye has healed.

Pitfalls

Do not assume that every ring is Acanthamoeba, because herpes and bacteria can produce similar rings
Do not start steroids before cultures when infection is possible
Do not forget to ask about contact lens history, water exposure, and previous herpes
Do not rely on a single negative scraping in a typical case, since repeat samples or confocal microscopy may reveal the organism

Prognosis

A Wessely ring often leaves a stromal scar.

Visual outcome depends on the cause, the speed of diagnosis, and the response to treatment.

References

Wessely K. Ueber anaphylaktische Erscheinungen an der Hornhaut. Muench Med Wochenschr. 1911;58:1713-1714.
Krachmer JH, Mannis MJ, Holland EJ, eds. Cornea. 3rd ed. Philadelphia: Elsevier; 2011.
Lorenzo-Morales J, Khan NA, Walochnik J. An update on Acanthamoeba keratitis: diagnosis, pathogenesis and treatment. Parasite. 2015;22:10.
Holland EJ, Schwartz GS. Classification of herpes simplex virus keratitis. Cornea. 1999;18:144-154.

Test yourself

A few questions straight from this article.

1 / 10 0 correct

A Wessely immune ring in the cornea represents which process?
The Wessely ring is a localized immune reaction in the corneal stroma and marks significant antigenic stimulation, making it a clue to the nature of the infection.
Which mechanism produces the annular infiltrate of a Wessely immune ring?
Antigen released centrally diffuses outward while antibody diffuses in from the limbal vessels; where they meet they precipitate and attract neutrophils and complement.
The clear zone between the central focus and a Wessely ring corresponds to what?
Closer to the central focus antigen is in excess, so no precipitate forms there and the cornea between the focus and the ring stays relatively clear.
A Wessely immune ring at the slit lamp usually measures what diameter?
The ring is a gray-white circular stromal band usually 2 to 4 mm across, concentric with a central focus of infection or foreign material.
Which feature separates a Wessely immune ring from the ring ulcer of marginal keratitis?
A staphylococcal or marginal ring ulcer sits near the limbus, whereas the Wessely ring lies in central or paracentral stroma with a clear zone inside it.
Which ring-shaped corneal finding forms around an old foreign body and contains iron?
The Coats white ring is a small, white, iron-containing ring around an old foreign body; the Fleischer ring encircles a keratoconus cone and the Kayser-Fleischer ring is peripheral copper in Wilson disease.
In herpes simplex stromal keratitis, what does an immune ring imply about treatment?
In herpetic disease the ring signals necrotizing stromal keratitis, which requires immune suppression together with antiviral cover.
What is characteristic of the ring infiltrate of Acanthamoeba keratitis?
In Acanthamoeba keratitis the ring develops later in the disease course, often suggesting a delay in diagnosis, and the keratitis is typically very painful.
Which drug classes are used for the prolonged treatment of Acanthamoeba keratitis?
Acanthamoeba keratitis requires prolonged therapy with biguanides and diamidines, in contrast to the antivirals or antibacterials used for other causes of an immune ring.
Which corneal outcome commonly follows a Wessely immune ring?
A Wessely ring often leaves a stromal scar, and the visual outcome depends on the cause, the speed of diagnosis and the response to treatment.

Ahmed Ophthalmologist

Writes and reviews the clinical articles on Educate. Every post is checked against peer-reviewed sources before it goes live.

Wessely Ring: The Immune Ring in the Corneal Stroma