Wessely immune rings following Keratorefractive Lenticule extraction: A case-based review

Abstract

Purpose

To describe two cases of immune-mediated corneal stromal infiltrates resembling Wessely immune rings following keratorefractive lenticule extraction (KLEx).

Observations

The first patient developed bilateral peripheral ring-shaped stromal infiltrates on postoperative day four, raising initial concern for infectious keratitis. Negative microbiologic work-up and favorable response to corticosteroids confirmed an immune-mediated etiology. The second patient presented with a unilateral peripheral stromal infiltrate on postoperative day one, which resolved with topical and subconjunctival corticosteroid therapy. In both cases, visual acuity improved to 20/20 without long-term sequelae.

Conclusions and importance

Wessely immune rings may develop after KLEx, mimicking infectious keratitis in the early postoperative period. Prompt recognition and differentiation of immune-mediated reactions from infections are essential to avoid unnecessary antimicrobial therapy and achieve favorable visual outcomes.

1. Introduction

Wessely immune rings are rare, circular stromal infiltrates typically associated with antigen-antibody complex deposition in the corneal stroma.¹ Although most commonly reported in infectious keratitis (e.g., Acanthamoeba, Herpes simplex virus), they can also result from sterile inflammation due to trauma, contact lens wear, or postoperative immune responses.² Keratorefractive Lenticule Extraction (KLEx), a flapless refractive procedure, presents unique challenges in interface access and management compared to LASIK. Though immune rings after KLEx are sparsely reported, such cases can mimic infectious keratitis, complicating diagnosis and management. Here, we present a structured review based on two cases of Wessely immune rings following femtosecond lenticule extraction (KLEx), focusing on diagnostic differentiation, treatment, and implications for postoperative care.

2. Methods

2.1. Protocol

No registered protocol exists for this case-based review. The study was conducted based on PRISMA guidelines and institutional best practices.

2.2. Eligibility criteria

We included case reports involving immune-mediated corneal stromal rings after KLEx. Exclusion criteria included cases involving confirmed infectious keratitis, non-refractive procedures, or incomplete follow-up data.

2.3. Outcome measures

Primary outcome: Resolution of stromal infiltrates and recovery of uncorrected distance visual acuity (UDVA). Secondary outcomes: Need for thorough washing, duration of treatment, and presence of residual opacities at final follow-up.

2.4. Search methods

We conducted a literature review using PubMed and Google Scholar through June 2025, using keywords: “Wessely immune ring,” “KLEx,” “corneal immune ring,” and “lenticule extraction.” No language or date restrictions were applied. Reference lists from included articles were also reviewed.

2.5. Study selection

Two authors independently screened all titles and abstracts. Full texts were reviewed for inclusion. Disagreements were resolved through discussion.

2.6. Data extraction and management

Data from selected reports and our own cases were extracted into a standardized form by both authors independently. Items included age, sex, refractive correction, energy dose, symptoms, clinical signs, treatment, and outcomes. Disagreements were resolved through consensus.

2.7. Risk of bias assessment

Given the nature of case reports, formal bias assessment tools were not applied. Quality was assessed qualitatively based on clarity, completeness, and diagnostic rigor.

2.8. Data synthesis and analysis

Qualitative synthesis was performed to identify patterns in clinical presentation, management, and outcome. No meta-analysis was conducted.

2.9. Certainty of the body of evidence and ‘summary of findings'

Due to the limited number and type of cases, formal GRADE assessments were not applied. Findings are summarized descriptively.

3. Results

3.1. Characteristics of included cases

Two patients were treated with KLEx using the Schwind Atos femtosecond laser. One received 630 mJ/cm² and the other 500 mJ/cm² of laser energy. Both developed immune rings postoperatively.

• •Case 1: Male in his 30s; bilateral ring infiltrates by day 4 (Fig. 1a, Fig. 1b); treated with subconjunctival and topical corticosteroids; followed for 6 months; full resolution with residual opacity. The refractive correction was programmed to treat −4.25 −1.50 × 7° in the right eye and −3.75 −2.00 × 10° in the left eye. The laser energy dose was 630 mJ/cm² and cap thickness as 120μm.

Fig. 1a.

Right eye —Anterior segment photograph showing peripheral corneal ring-shaped opacities (Wessely ring). Case 1. POD4.

Fig. 1b.

Left eye —Anterior segment photograph showing peripheral corneal ring-shaped opacities (Wessely ring). Case 1. POD4

On postoperative day one, uncorrected distance visual acuity (UDVA) was 20/20−2 in the right eye and 20/20 in the left eye. The early postoperative course was unremarkable. However, on day four (Fig. 1a, Fig. 1b), the patient returned to the clinic with complaints of decreased visual acuity. UDVA had declined to 20/50 in the right eye and 20/30 in the left eye.

Slit-lamp biomicroscopy revealed a peripheral, dense, ring-shaped stromal infiltrate in both eyes without hypopyon or satellite lesions. Corneal sensitivity was reduced. Given the use of a scleral suction interface during the femtosecond laser procedure, mild conjunctival injection was anticipated. Nonetheless, the patient was referred for in-patient observation and management to rule out possible infectious keratitis.

Comprehensive laboratory testing was initiated, including complete blood count, inflammatory markers, and corneal scrapings for Gram staining, cultures, and microscopy to exclude bacterial, fungal, and protozoal pathogens. Empirical treatment was initiated, consisting of topical levofloxacin 0.5 % (1 drop four times daily), tropicamide 1 % (1 drop twice daily, discontinued after 24 hours), and subconjunctival dexamethasone 0.4 % (0.5 mL once daily for five days). A topical moisturizing gel with dexpanthenol was also prescribed five times daily for three weeks.

By postoperative day five (Fig. 2a, Fig. 2b), UDVA had improved to 20/30 in the right eye and 20/25 in the left. Following pharmacological mydriasis, multiple fine stromal infiltrates were observed centrally, appearing as faint, single, discrete lesions. These infiltrates demonstrated a distribution pattern consistent with a developing Wessely immune ring, characterized by central-to-peripheral progression, resembling the C1 morphological subtype (Fig. 3a, Fig. 3b, Fig. 3c). By postoperative day nine (Fig. 4a, Fig. 4b), the patient's UDVA had further improved to 20/25 in the right eye and 20/20 in the left eye, with marked reduction in both central and peripheral stromal infiltrates. After 6 months from surgery only residual peripheral infiltrates left on both eyes (Fig. 5a, Fig. 5b).

• •Case 2: Female in her 20s; unilateral infiltrate by day 1; managed similarly; full recovery by 2 weeks; no residual opacity at 3-month follow-up. Bilateral refractive correction was performed using the Keratorefractive Lenticule Extraction (KLEx) procedure targeting −8.50 −1.00 × 174° in the right eye and −8.00 −0.75 × 171° diopters of myopia in the left eye. The procedure was uneventful, with laser energy dose of 500 mJ/cm² and cap thickness as 110μm.

Fig. 2a.

Right eye—Anterior segment photograph after topical mydriasis showing central numerous single stromal infiltrates and peripheral corneal ring-shaped opacities (Wessely ring). Case 1. POD5.

Fig. 2b.

Left eye—Anterior segment photograph after topical mydriasis showing central numerous single stromal infiltrates and peripheral corneal ring-shaped opacities (Wessely ring). Case 1. POD5.

Fig. 3a.

Corneal OCT showing infiltrates’ location, En face(depth) (Wessely ring). Case 1. POD5.

Fig. 3b.

Corneal OCT showing infiltrates’ location, En face(depth), Epithelium Map (Wessely ring).Case 1. POD5.

Fig. 3c.

Corneal OCT showing infiltrates’ location, En face(depth) (Wessely ring). Case 1. POD5.

Fig. 4a.

Right eye—Anterior segment photograph dynamics after treatment (Wessely ring). Case 1. POD9.

Fig. 4b.

Left eye—Anterior segment photograph dynamics after treatment (Wessely ring). Case 1. POD9.

Fig. 5a.

Right eye —Anterior segment photograph showing residual infiltrates. Case 1. POM6.

Fig. 5b.

Left eye —Anterior segment photograph showing residual infiltrates. Case 1. POM6.

On postoperative day one (Fig. 6), uncorrected distance visual acuity (UDVA) was 20/25 in the right eye and 20/20 in the left. Slit-lamp examination revealed a small, localized stromal infiltrate in one peripheral quadrant of the right cornea, without associated epithelial defect, conjunctival injection, or anterior chamber reaction. The left eye was unremarkable. Given the isolated nature of the infiltrate and the absence of clinical signs of infection, the initial management was directed toward an immune-mediated etiology.

Fig. 6.

Anterior segment photograph showing residual infiltrates. Case 2. POD1. Right eye.

The patient was treated immediately with a subconjunctival injection of dexamethasone 0.4 % (0.5 mL) in the right eye. Additionally, a standard postoperative regimen was initiated, including topical levofloxacin 0.5 % four times daily, preservative-free moisturizing eye drops with dexpanthenol five times daily, and topical dexamethasone 0.1 % four times daily. Subconjunctival injections of dexamethasone were continued for three consecutive days in the affected eye, with close follow-up.

By postoperative day four, the patient had achieved UDVA of 20/20 in both eyes. On slit-lamp examination, only subtle residual infiltrates remained in the inferior-temporal quadrant of the right cornea, spanning approximately the 7 to 9 o'clock positions. No new lesions were identified, and there was no progression or signs of infection. Unfortunately, only one figure was possible to capture in this Case 2.

3.2. Risk of bias assessment

As this is a case-based review, limitations include small sample size and lack of control groups.

3.3. Outcomes

Both patients achieved 20/20 UDVA at final follow-up. No infection was confirmed. Subconjunctival dexamethasone was effective. OCT imaging localized infiltrates to the interface. Energy dose variation had no apparent impact on immune ring development.

4. Discussion

These cases highlight a rare but clinically significant postoperative complication of KLEx: the development of immune-mediated stromal rings that mimic infection. Accurate and timely diagnosis is critical to avoid unnecessary and potentially harmful antimicrobial use. In both patients, the rapid resolution with corticosteroids and absence of microbial growth supported an immune, rather than infectious, etiology.

Immune ring formation is classically associated with infectious keratitis such as Acanthamoeba, herpes simplex, or fungal infections, and has only rarely been reported after keratorefractive procedures. Previous literature describes immune rings following LASIK, often linked to interface debris or retained antigens. In KLEx, however, the narrower side-cut incision limits the ability to irrigate the interface thoroughly. This restricted irrigation may allow residual micro-debris, laser-induced photodisruption byproducts, or contaminants to persist within the stromal pocket, thereby acting as potential antigenic triggers for immune ring formation. The authors assume this mechanical limitation could partly explain the predisposition for immune responses after KLEx compared with LASIK. Routine interface irrigation, although not currently standard in KLEx, may therefore merit consideration to reduce the risk of antigen retention.

Interestingly, both cases developed immune rings despite differing laser energy doses, suggesting that energy settings alone are not a major contributing factor. Instead, the pathogenesis seems more closely related to antigen persistence and host immune response. Optical coherence tomography (OCT) proved especially valuable in both cases, as it confirmed the intrastromal location of infiltrates and helped exclude epithelial or endothelial involvement. OCT, together with clinical course and microbiological testing, should be considered essential in differentiating immune-mediated reactions from true infections.

From a therapeutic perspective, these findings emphasize the importance of early anti-inflammatory intervention. In particular, subconjunctival corticosteroid injection in addition to topical therapy appeared effective in rapidly suppressing inflammation and preventing stromal damage. While the sample size is small, our experience suggests that aggressive steroid therapy may be warranted once infection has been reasonably excluded.

The main limitation of this report is the small number of cases and the observational nature of the findings. The proposed role of retained antigens in KLEx-related immune rings remains speculative and requires validation through larger case series or registries. Nevertheless, these cases underscore a need for heightened awareness among refractive surgeons and corneal specialists: immune rings should be recognized as a possible complication of KLEx, and careful postoperative surveillance, timely imaging, and prompt initiation of anti-inflammatory therapy can help preserve excellent visual outcomes.

CRediT authorship contribution statement

Stanislav Pushkar: Writing – review & editing, Writing – original draft, Visualization, Validation, Supervision, Software, Resources, Project administration, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation. Asset Omirzak: Snezhana Panchenko, Data curation. Igor Remesnikov: Supervision, Clinical management of the cases, Resources, Writing – review & editing.

Patient consent

Consent to publish this case report has been obtained from the patient(s) in writing.

Learning points

• •Wessely immune rings can occur after KLEx, even in the absence of infection.
• •Differentiating immune-mediated reactions from infectious keratitis is essential.
• •OCT imaging aids in localizing interface-related stromal infiltrates.
• •Subconjunctival corticosteroids enable rapid resolution and favorable visual outcomes.
• •Laser energy dose does not influence the risk of immune ring formation.

Disclosures

Institutional review board approval: Not required for retrospective case reports. Written informed consent was obtained from both patients.

Authorship

All authors attest that they meet the current ICMJE criteria for Authorship.

Funding

No funding or grant support.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper: The author is an Editorial Board Member/Editor-in-Chief/Associate Editor/Guest Editor for this journal and was not involved in the editorial review or the decision to publish this article.