Corneal biomechanical changes in allergic conjunctivitis

Background:To explore corneal biomechanical changes,identify related factors and determine early indicators of keratoconus(KC)development risk in allergic conjunctivitis(AC)patients.Methods:A 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).Results:The 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(TBl)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).Conclusions:AC patients should be advised to routinely undergo corneal tomographic and biomechanical measurements,and the TBl could be used as an indicator of KC development risk in AC patients.Trial registration:Corneal Biomechanical Changes of Allergic Conjunctivitis,NCT04299399.Registered March 3,2020-Retrospectively registered.