Abstract
Purpose :
Minimal persistent inflammation at the conjunctival and nasal epithelium of asymptomatic rhinitis patients has been detected, revising therapeutic strategy to target the inflammatory response in preference to symptom-based therapy. We have previously shown increased density and morphology of dendritiform cells in the cornea and conjunctiva in active allergic conjunctivitis during the pollen season. This study aimed to assess whether the changes in dendritic cells persisted during the silent symptom-free phase of allergy.
Methods :
Twenty allergic participants (mean age 43.3±14.3 years, 55% female) were examined during active allergic conjunctivitis and when the allergy was in silent phase (at least 4 symptom-free weeks). In vivo confocal microscopy (HRTIII) was performed on the right eye in five locations (central cornea, inferior whorl, temporal corneal periphery (1mm inside limbus), temporal corneal limbus, and temporal bulbar conjunctiva (2-3 mm away from limbus)). Five best-focused, non-overlapping images from each location and one from the inferior whorl were analysed. Dendritiform cells (DC) were counted manually, and morphology of corneal cells was recorded using grading scales for cell body size, dendrite length, and dendrite shape. Differences between phases (Wilcoxon Signed Rank test) and between regions (Friedman with post-hoc tests) were examined.
Results :
DC density in the conjunctiva was higher in the active phase than the silent (p=0.001) but was not significantly different between phases at any of the corneal regions (central p=0.70; periphery p=0.32; limbus p=0.14; inferior whorl p=0.84). DC density was higher at the limbus than all other locations (p≤0.001) during both phases, and the fewest DC were observed at the inferior whorl. During the active phase,DC cell body size at all corneal locations was larger (p≤0.03), and dendrites were longer at the corneal periphery and limbus (p<0.01), than in the silent phase. Conjunctival DC morphology was assessed qualitatively and observed in both phases to have long thin dendrites and in some participants a wire-netting pattern.
Conclusions :
This study demonstrated the persistence of dendritiform immune cells in the cornea, but not in the conjunctiva, in the absence of symptoms in patients with allergic conjunctivitis. These cells were observed to have a lower morphology grade suggesting a less activated state.
This is a 2021 ARVO Annual Meeting abstract.