A recent systematic review and meta-analysis examined the association between keratoconus (KC) and inflammatory bowel disease (IBD).¹ Recognizing potential associations between systemic diseases and keratoconus may inform targeted screening strategies, facilitate earlier detection, and guide early clinical management.

IBD includes 2 major chronic inflammatory conditions of the gastrointestinal tract: Crohndisease (CD), which can affect any segment of the digestive tract; and ulcerative colitis (UC), which primarily involves the colon and rectum. IBD represents a significant global health burden, with particularly high prevalence in Western countries.² The age of onset varies by sex, with a higher risk of childhood-onset disease reported among males.³ Despite growing interest in the potential relationship between systemic inflammatory disorders and corneal ectatic disease, the literature examining the association between IBD and KC remains limited, suggesting the need for a comprehensive systematic review.

A search was performed on 5 databases (PubMed, Ovid Medline, Scopus, Web of Science, and Embase) on October 16, 2024. The selected papers were identified as patient studies or genetic association studies for analysis. Odds ratio was the primary outcome measure. For patient studies, meta-analysis and test of assumptions were conducted. Additionally, bias assessments were conducted using Q-GENIE and ROBINS-E.

Prospective and retrospective studies evaluating the association between IBD, UC, and CD, and KC or suspected KC were eligible for inclusion. Studies were included regardless of sample size. Studies involving patient cohorts with other ocular comorbidities were excluded. Ex vivo studies, animal studies, studies involving nonhuman subjects, and publications in languages other than English were also excluded.

The literature search identified 299 publications. Nine met the inclusion criteria for the systematic review, and three were included in the meta-analysis. The pooled odds ratio from patient-based studies was 1.39 (95% confidence interval [CI]: 0.82–2.37), indicating no statistically significant association between IBD and KC.

Among the 4 studies evaluating CD, no statistically significant association with KC was identified (all P>.05). In contrast, all 5 genetic association studies identified associations between KC and IBD overall and/or UC, suggesting a potential shared genetic susceptibility.

In patient studies, there was no consistent evidence of an association between KC and IBD. However, there was evidence of a genetic association between IBD and KC. This association appears most prominent and consistent regarding UC.

This information may be beneficial for practitioners to aid in the early diagnosis of KC and researchers to develop screening tools. That said, future clinical studies are required to confirm these findings in patient cohorts and understand any underlying pathophysiology.

References

1. Lahijanian S, Kandel H, Kha R, Watson SL. Association between keratoconus and inflammatory bowel disease: a systematic review and meta-analysis. Cornea. 2026;45(11):1467-1472. doi: 10.1097/ICO.0000000000004201

2. Kobayashi T, Siegmund B, Le Berre C, et al. Ulcerative colitis. Nat Rev Dis Primers. 2020;6:74. doi: 10.1038/s41572-020-0205-x

3. Shah SC, Khalili H, Gower-Rousseau C, et al. Sex-based differences in incidence of inflammatory bowel diseases: pooled analysis of population-based studies from Western countries. Gastroenterology. 2018;155:1079-1089.e3. doi: 10.1053/j.gastro.2018.06.043 

Melissa Barnett, OD, FAAO, FSLS, practices at Baker Optometry. She also is an International Coaching Federation (ICF) associate certified coach. She has received remuneration from ABB, AbbVie, Alcon, Azura, Bausch + Lomb, BCLA, Bruder, Cloudbreak Pharma, Dompé, Epion, OCuSOFT, ScienceBased Health, STAPLE Program, Tarsus, Tenpoint Pharmaceuticals, and Théa Pharma.

 This content is sponsored by Contamac.