AIM:To investigate the correlation between demodex infection with corneal cell density changes and ocular surface function in patients with blepharo kerato conjunctivitis(BKC).

METHODS: Ninety-four patients with BKC(BKC group)at Department of Ophthalmology of our hospital from July 2019 to July 2020 were selected as the research objects, in addition, 80 matched healthy volunteers were selected as control group. The BKC patients were divided into infected group(45 cases)and uninfected group(49 cases)according to whether they were infected with demodex. According to the number of demodex detected in eyelashes, there were 17 cases of suspicious infection, 18 cases of moderate infection and 10 cases of severe infection. All subjects were examined by laser confocal microscopy, and the cell density in the superficial stromal layer of the central cornea and peripheral cornea was calculated. The ocular surface function \〖Schirmer test, Ocular Surface Disease Index(OSDI)\〗, eyelid margin abnormality score, corneal fluorescence stain and tear film break-up time(TF-BUT)of patients with BKC were examined, and the correlation between demodex infection with corneal cell density and ocular surface function in patients with BKC was analyzed.

RESULTS: Compared with those in the control group, the cell density in the superficial stromal layer of the central cornea and peripheral cornea was lower in the BKC group(P<0.05), and the OSDI, eyelid margin abnormality score and corneal fluorescence stain score were higher(P<0.05); the cell density in the superficial stromal layer of the central cornea and peripheral cornea of patients in uninfected group, patients with suspicious demodex infection, moderate demodex infection and severe demodex infection decreased in turn(P<0.05), and the OSDI, eyelid margin abnormality score and corneal fluorescence stain score increased significantly in turn(P<0.05); the degree of demodex infection was negatively correlated with the cell density in the superficial stromal layer of the central cornea and peripheral cornea in patients with BKC(P<0.05), and was positively correlated with OSDI, eyelid margin abnormality score and corneal fluorescence stain score(P<0.05).

CONCLUSION: The severity of demodex infection has a significant negative correlation with the cell density in the superficial stromal layer of the central cornea and peripheral cornea in patients with BKC, has a significant positive correlation in patients with ocular surface dysfunction.