Abstract
Purpose :
Corneal and conjunctival epithelial dendritiform cells (CEDC, CjEDC) are an essential part of the ocular immune response, including the allergic response. Confocal microscopy allows observation of these cells in patients in real-time. This study examined inter-observer reliability of CEDC and CjEDC density and morphology measurements in normal and allergic patients.
Methods :
In vivo confocal microscopy images (HRTIII-Rostock) from the corneal sub-basal and conjunctival epithelium of the right eye of 66 participants (mean age 36.6±12.0 years, 56% female; 33 patients with normal corneas and 33 patients with active ocular allergy) were independently assessed by two experienced observers. Five best-focused, non-overlapping images were selected for each participant from the central cornea, temporal far peripheral cornea, temporal corneal limbus, temporal bulbar conjunctiva, and one image from the corneal whorl. CEDC and CjEDC density were counted manually, and the highest-grade morphology of corneal cells was recorded using grading scales for CEDC cell body size, dendrite length and dendrite shape. The level of agreement between observers was analysed for density by calculating the coefficient of repeatability (CoR, Bland and Altman method) and Intraclass Correlation Coefficient (ICC), and for morphology using Weighted Cohen's Kappa.
Results :
There was a strong level of agreement between the two observers for CEDC density at the central (CoR=±11.9, ICC=0.99), far peripheral (CoR ±14.3, ICC=0.99) and limbal cornea (CoR ±28.0, ICC=0.96), with no significant bias between observers. There was a significant difference between observers for density measurements at the corneal whorl (p<0.001; CoR ±29.10, ICC=0.98). Repeatability of density measurements at the conjunctiva was comparatively poorer (CoR ± 19.1, ICC=0.97), with no significant inter-observer bias. For all three CEDC morphology parameters, there was good to strong inter-observer agreement at all corneal locations (k= 0.69 to 1.0).
Conclusions :
The strong inter-rater agreement in CEDC density and good agreement in CEDC morphology and CjEDC density measurements supports the validity and reliability of in vivo dendritic cell assessment using confocal microscopy using manual counting, a novel morphology grading scale by trained observers.
This is a 2021 ARVO Annual Meeting abstract.