Abstract
BackgroundTo explore corneal biomechanical changes, identify related factors and determine early indicators of keratoconus (KC) development risk in allergic conjunctivitis (AC) patients.MethodsA total of 50 patients, including 20 eyes without AC and 30 eyes with AC were enrolled in this study. All patients underwent a complete ocular examination, including evaluations of clinical manifestations of AC, corneal tomography and densitometry by Pentacam, corneal biomechanics by Corvis ST, and corneal and epithelial thickness mapping by RTvue optical coherence tomography (OCT).ResultsThe index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), index of height decentration (IHD) and Belin/Ambrosio enhanced ectasia total deviation index (BAD-D) were significantly higher in the AC group than in the non-allergic conjunctivitis (NAC) group (P < 0.05). The tomography and biomechanical index (TBI) was also significantly higher in the AC group (P = 0.04). The average epithelial thickness in the 2–7 mm annulus was significantly thinner in the AC group than in the NAC group (P < 0.05). The average densitometry of the total cornea and the anterior layer were higher in the AC group than in the NAC group (P < 0.001). The ISV, IVA, KI, IHD and BAD-D were significantly correlated with the TBI and changes in corneal epithelial thickness in AC patients (P < 0.05). The changes in epithelial thickness were closely related to the eye rubbing frequency and allergic sign scores (P < 0.05).ConclusionsAC patients should be advised to routinely undergo corneal tomographic and biomechanical measurements, and the TBI could be used as an indicator of KC development risk in AC patients.Trial registrationCorneal Biomechanical Changes of Allergic Conjunctivitis, NCT04299399. Registered March 3, 2020 - Retrospectively registered.
Highlights
To explore corneal biomechanical changes, identify related factors and determine early indicators of keratoconus (KC) development risk in allergic conjunctivitis (AC) patients
We found that the corneal morphology, biomechanics and epithelial thickness were altered in AC patients, as indicated by elevated corneal irregularity and asymmetry, an increased tomography and biomechanical index (TBI) and a thinner corneal epithelium, which were further found to be correlated with the eye rubbing frequency and ocular allergic sign scores
By Scheimpflug tomography examination, we found that corneal surface irregularity and asymmetry were significantly increased in AC patients, which was indicated by higher index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), index of height decentration (IHD) and Belin/Ambrosio enhanced ectasia total deviation index (BAD-D) values compared to those in the non-allergic conjunctivitis (NAC) patients
Summary
To explore corneal biomechanical changes, identify related factors and determine early indicators of keratoconus (KC) development risk in allergic conjunctivitis (AC) patients. KC is a degenerative disorder of the cornea that was first described as a noninflammatory ectatic disease, but recent studies have implicated that the action of inflammatory mediators are involved in KC development and progression [8,9,10]. Corneal injury and elevated inflammatory mediator release caused by excessive eye rubbing in AC patients have been proposed as possible mechanisms of KC development. It has been proven that AC and eye rubbing can elevate the concentrations of inflammatory molecules in tears, including MMPs, interleukin (IL)-4, IL-5, IL-10, interferon (IFN)-γ and tumor necrosis factor-α (TNF)-α, which are involved in keratocyte apoptosis and tissue remodeling [8, 11, 13, 14]
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