To date, numerous clinical scores are available for VKC according to clinical signs and symptoms that are assessed in the clinic by taking patients’ history and physical examinations.[14] No scoring system has been shown to be superior or more credible than others.[4] The variability of treatment choices and the lack of a standardized treatment protocol leads to prolonged treatment periods, various attempts of different medications, relapse episodes and added emotional and physical stress on the child and parents. Patients were divided by severity and treated according to our treatment protocol based on clinical judgment as discussed earlier.
The mean number of days under treatment was significantly higher in the tacrolimus as 2nd line group than the tacrolimus 1st line group. We also show a trend towards a longer follow up duration when using tacrolimus as 2nd line treatment compared to 1st line treatment.
Chatterjee et al described tacrolimus ointment as effective and safe for patients diagnosed with VKC who are refractory to topical steroids.[15] Our results suggest early treatment with tacrolimus in moderate to severe patients will shorten the duration of treatment and the follow up period.
Our series also shows that treating with steroids alone doubles the mean number of treatments per day compared to both tacrolimus groups. It has been shown in adults that longer duration and a higher frequency of treatments per day lower the compliance.[16] Treating children, compliance issues are even more significant and more treatments per day can be even more challenging for parents for many reasons, such as children’s reluctance to cooperate, the need for parent availability during the day, and fatigue over a long treatment period. These may lead to lower compliance and eventually treatment ineffectiveness. Therefore treating with tacrolimus poses a benefit of needing less treatments per day thus improving compliance. In addition, treating with tacrolimus as a 1st line shortens the total duration of treatment and the need for long term follow up.
The need for additional topical steroid treatment for patients refractory to tacrolimus ointment has also been described.[15] In our series, there was a similar number of refractory patients requiring topical supplemental steroid treatment in both tacrolimus groups which shows similarity of severity between the groups, making the groups more comparable. Therefore, we suggest that patients originally classified as moderate would benefit an early tacrolimus treatment rather than initial treating with steroids.
The mean number of visits was significantly higher in the tacrolimus 2nd line group compared to the two other groups. Even though this data is incomparable between the groups due to different follow up periods, it can be an indicator of uncontrollable disease which needs more attention. Therefore it supports tacrolimus as 1st line of treatment to achieve fewer visits.
Our analysis revealed that those treated with topical steroids or artificial tears alone were considered mild cases. We observed that this group showed a lower number of relapses (p = 0.05), fewer visits in the clinic (p = 0.001), and shorter follow-up time (p = 0.194) than the two groups treated with tacrolimus. The patients who did not receive tacrolimus ointment represented the mildest cases in this series; therefore, these results are evidently attributed to the severity at presentation and not to the effectiveness of treatment.
On the other hand, our analysis revealed that the children treated with tacrolimus ointment as 1st line treatment had a higher number of relapses. Due to higher severity level at baseline in this group, we do not think this should be attributed to treatment.
The four children with the most severe and refractory disease, with the longest treatment duration, were all subjected to environmental stress factors, both socially and psychologically. The association of psychological stress with other atopic diseases, such as atopic dermatitis, have been described. However, a specific association of such stress with VKC remains unknown.[6, 17]
Our series showed a variability in time to achieve remission according to treatment received. We see a trend towards a shorter time to achieve remission and shorter duration of tacrolimus treatment time for patients receiving tacrolimus as a 1st line treatment compared to patients who received tacrolimus as 2nd line treatment. Although these differences were not statistically significant (p = 0.105 and p = 0.513, respectively), this data supports our hypothesis that early tacrolimus treatment is beneficial.
The most concerning adverse effect related to topical tacrolimus use is the risk of T-cell lymphoma. A debate in the current literature revolves around the possible correlation between topical use of tacrolimus for skin treatment and non-ophthalmic use. A multicenter cohort study found an increased risk of lymphoma in children and cutaneous T-cell lymphoma in adults who initiated treatment with tacrolimus for atopic dermatitis. However, the increased risk was small and the authors mentioned that cutaneous T-cell lymphoma may be misdiagnosed as atopic dermatitis, and that this may have caused an overestimation of the results.[18] On the other hand, in a meta-analysis that assessed the correlation between lymphoma risk and topical calcineurin inhibitors (e.g. tacrolimus), only one article reported this association in regard to topical skin use for atopic dermatitis.[19] A Cochrane review did not find evidence associating a risk of malignancies with the use of topical tacrolimus.[20] Moreover, many have questioned such correlation due to the possible association between atopic dermatitis and the increased risk of malignancy and lymphoma, which would render the topical treatment a confounding factor.[21–23] A long term follow up for topical ophthalmic use of tacrolimus 0.1% ointment found it to be an effective and safe treatment for atopic keratoconjunctivitis.[24]
Adverse effects of topical steroid drops include elevated intraocular pressure and increased risk for posterior subcapsular cataract.[25] Some topical steroid agents are considered to have a low risk of elevating intraocular pressure. However, manufacturers still list this as a possible adverse effect. In our study, no cases of cataract formation or elevated intraocular pressure were observed. Beside itching and foreign body sensation, there were no side effects of tacrolimus ointment use.
Therefore we believe tacrolimus to be a safe and efficacious treatment for VKC also as a 1st line treatment.
Based on our results, we suggest a treatment protocol for an effective treatment for VKC patients, stratified according to the severity grade at presentation (Fig. 2).
According to our treatment protocol, Mild cases should be treated with a 1 month course of topical steroids twice a day combined with artificial tears. In cases that are partially resolved, treatment should be adjusted by increasing steroid dosage. Initiation of tacrolimus ointment should be reserved for cases with no improvement.
Moderate cases should be treated initially with 1 month of topical steroid drops 3–4 times a day with artificial tears 4 times a day. If not improved, we suggest to switch treatment to tacrolimus ointment 0.03% and classify them as severe cases.
Severe cases should be treated directly with tacrolimus 0.03% ointment once a day combined with artificial tears 4 times a day. Assessment is suggested after 1 month and remised cases should be gradually tapered and switched only to artificial tears. Refractory cases should be treated with a higher dose (tacrolimus 0.1% once a day or 0.03% twice a day) or addition of topical steroids.
This study has a number of limitations. After exclusion of patients who did not meet eligibility criteria, the total number of patients was small.
The history collected in the clinic has inherent difficulties. Data is based on parents’ reports of home treatment which sometimes may be incorrect. Each patient has their own timeline which is not congruent to other patients. In order to bypass this challenge and make a correct statistical analysis we used objective measurements as discussed earlier. Patients were assessed according to their own timelines; and their own number, interval, and frequency of clinical visits, and duration of follow up period. However, this bias cannot be fully corrected. We believe that a large randomized prospective cohort trial can fully evaluate this protocol.