Background
Vernal keratoconjunctivitis is a chronic allergic disease that affects the ocular surface and is associated with a history of atopy. This disease predominantly affects the pediatric male population age 5 to 15 years [
1] and usually disappears after puberty. The manifestation is usually bilateral and occurs seasonally, especially in the spring [
2]. Ophthalmologic examination indicates papillary hypertrophy, Horner-Trantas dots, and, rarely, corneal shield ulcer; the latter manifestation is one of the most severe complications of this disease and can progress to loss of vision [
3,
4].
Two hypotheses can explain the development of shield ulcers. The first is the mechanical friction generated by the giant papillae, causing a micro-corneal trauma that later evolves into a shield ulcer. The second is an allergic response produced by the toxic action of inflammatory mediators released by eosinophils [
5].
Several types of shield ulcer treatments have been proposed and studied, including topical immunosuppressive agents (corticosteroids, cyclosporine, and tacrolimus), non-steroidal anti-inflammatory drugs, homeopathic medications, surgical debridement of the corneal plaque to remove cytotoxic cells, and amniotic membrane transplantation [
3,
6]. New drugs are being studied and can potentially be used in treatment [
7]. However, the predominance of clinical approaches warrants further study of early surgical debridement, which may be an effective treatment option because of its ability to rapidly interrupt the course of the disease [
8,
9], as demonstrated in these two cases. In addition, the timing of the surgical procedure is crucial because it affects pediatric patients, for example, high levels of amblyopia and strabismus are associated with delayed treatment.
Discussion and conclusions
Vernal keratoconjunctivitis is a subtype of chronic allergic conjunctivitis that affects the eyes, usually bilaterally, as observed in these two cases, and the prevalence is higher in the spring [
5] in countries with dry and hot climates [
3]. Brazil, with a tropical climate, is a favorable location for disease development. The most affected population is male children of age 5 to 15 years [
1], with a proportion of three boys to one girl until puberty. After this period, men and women are equally affected [
10]. Our patients were aged 4 and 7 years.
This disease has three forms of presentation: (1) the eyelid form, which is more common in Europe and the USA and affects the papillae in the upper palpebral conjunctiva, which may fuse and form giant papillae usually larger than 1 mm; (2) the bulbar/limbal form, which is more frequent in Asia and Africa and is characterized by hypertrophy of the limbal papillae, with a tendency to fuse and present a gelatinous appearance; and (3) the mixed form, which is a combination of the palpebral and limbal form and is more common in tropical countries [
6]. Our cases belong to type 3 since they have a palpebral, limbal, and corneal component.
The symptoms are usually more severe and acute than those associated with seasonal conjunctivitis, as observed in the two reported cases. Ophthalmologic examination indicates hyperemia, chemosis, papillary hypertrophy, the presence of giant papillae in some cases, and Horner-Trantas dots formed by degenerating eosinophils, potentially leading to shield ulcer due to trauma or toxicity [
3].
The indication for treatment of shield ulcers differs according to the degree of severity, which varies from 1 to 3 [
5]. Grade 1 ulcers have a clear base and margins, no macroscopic inflammatory material, a good response to drug treatment, and rapid re-epithelialization. Grade 2 ulcers take longer to re-epithelialize because of the presence of inflammatory material at the margins and base, and the complication rates are consequently higher. In grade 3 ulcers, proteins are deposited in the lacrimal film and Bowman’s layer. Therefore, surgical treatment is indicated starting at grade 2 lesions, especially plaque removal, because short-term re-epithelialization rates are higher and the number of complications is lower than that associated with drug treatment [
5,
6].
Treatment depends on several factors, including patients’ or parents’ choice, doctor’s surgical ability, the accessibility of hospital, the cost of the procedure, and ulcer progression. Drug treatment primarily involves the use of immunosuppressants, including corticosteroids and tacrolimus, non-steroidal anti-inflammatory drugs, and homeopathic medication. Treatment in the form of topical eye drops can be used in lower-grade ulcers [
11] and was instituted in these two cases. However, both of our cases were treated with topical eye drops but it was not enough so surgical removal was necessary. In addition to plaque removal, amniotic membrane transplantation can be associated with drug treatment, but the technical difficulties are greater [
5].
In both patients the anesthetic procedure was performed using sedation associated with topical anesthesia. With the help of a blunt spatula, the cleavage plane of the protein membrane was identified. The membrane is pulled gently with tooth tweezers, avulsed with smooth movements and removed in a single piece. Although we have presented only two cases, few studies to date have discussed the advantages of excision of shield ulcers to interrupt the course of the disease. A database search in PubMed, ScienceDirect, Scopus, Google Scholar, SciELO, and LILACS yielded the following articles on the subject (in chronological order): Solomon
et al. [
12], Ozbek
et al. [
8], Fukuda
et al. [
13], Caputo
et al. [
14], Reddy
et al. [
5], Mushtaq
et al. [
9], Cameron [
15], and Das [
16] (Table
3).
Table 3Literature review on surgical excision of shield ulcers
Cameron | 1995 | 23 | Mean 12.7 | Topical cell stabilizers | Variable | Effective in 20 of 23 patients |
| 2004 | 3 | 4, 7.5, 9 | Topical steroid | 8 to 15 months | Effective in all patients |
| 2006 | 1 | 12 | Cyclosporine 0.05% | 10 months | Effective |
| 2010 | 1 | 27 | Fluorometholone and sodium cromoglicate eye drops | 2 months | Effective |
| 2012 | 4 | Children (age not available) | Cyclosporine and topical lubricating eye drops | 12 months | Effective in all patients |
| 2013 | 21 | Mean 12 | Sodium cromoglycate 2% or 4%, prednisolone acetate 1% or fluorometholone 0.25% and lubricating eye drops | 18 months | Effective in 20 of 21 patients |
| 2016 | 1 | 25 | Topical steroid, mast cell stabilizers, and lubricating eye drops | 2 months | Effective |
| 2017 | 1 | 11 | Olopatadine and lubricating eye drops | 3 months | Effective |
The effectiveness of plaque removal according to the identified articles is high (Table
3). If the most effective treatment is not instituted, as occurred in case 2, in which a previous drug treatment was used for an extended period, shield ulcers may progress to grade 3 [
17].
Surgical treatment involves scraping the base and edges of the ulcer and removing the inflammatory plaque [
4,
12]. Intraoperative optical coherence tomography-guided has been described as a method for monitoring the dissection depth of the shield ulcer with plaque [
18]. In the case series presented by Cameron [
15], 20 (87%) of the 23 ulcers with plaque formation exhibited rapid re-epithelialization after plaque removal, justifying the creation of an algorithm to guide treatment because only 25% of grade 2 ulcers exhibited satisfactory re-epithelialization with drug treatment alone. The results obtained by Ozbek
et al. [
8], Fukuda
et al. [
13], Mushtaq
et al. [
9], and Das [
16] were excellent. Caputo
et al. [
14] found that, among 700 children under treatment, four developed shield ulcers, and they all experienced good disease resolution after plaque removal. Excimer laser phototherapeutic keratectomy was employed as an auxiliary treatment in three eyes with shield-shaped corneal ulcers and plaques caused by vernal keratoconjunctivitis [
19]. Shield ulcer regression with drug treatment is rare in cases in which white or yellowish deposits develop, emphasizing the importance of surgical treatment [
2,
8].
In both cases, surgical treatment was curative and definitive in the 7-month follow-up period. The risk of side effects of medications and clinical complications, including bacterial infection, emphasizes the need for surgical treatment of grade 2 and grade 3 ulcers to interrupt the course of the disease [
2], as occurred in the two evaluated patients. The delay in surgical intervention may result in other complications, such as amblyopia and strabismus in pediatric patients [
12]. Furthermore, as the timing of the surgical procedure is crucial, due to the high levels of amblyopia and strabismus associated with delayed treatment, we also suggest that the surgical approach should be considered the first choice in cases of types 2 and 3.
The results of these two cases provided evidence of the efficacy of surgical treatment of grade 2 and 3 shield ulcers refractory to drug treatment. In selected cases, that is, in grade 2 and 3 ulcers, surgical treatment interrupts the course of the disease and is much more effective than drug treatment, demonstrating the need to include this strategy in the therapeutic arsenal because of its immediate benefit to the patient.
The number of reported cases is small because the disease is rare. Therefore, new studies with more cases are necessary to prove the effectiveness of the described method.
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