Minglu Ma,* Xiaojuan Dong,* Jing Wu, Jiayin Peng, Ruilin Guo, Yi Yu, Chenjia Xu, Chen Ouyang, Ting Huang

State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Ting Huang, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Room 1507, Clinical Building, Zhongshan Ophthalmic Center, Sun Yat-sen University, 7 Jinsui Road, Tianhe District, Guangzhou, 510060, People’s Republic of China, Tel +86 13682205425, Fax +86 20 87333566, Email thuang@vip.163.com

Objective: To explore alterations in tears and ocular surface throughout Descemet’s Membrane Endothelial Keratoplasty (DMEK), thereby offering valuable insights for clinical intervention.
Methods: This study was conducted on 84 patients (84 eyes) with CED and received DMEK who visited the Zhongshan Ophthalmic Center of Sun Yat-sen University from April 2022 to January 2024. All patients were evaluated preoperatively and 1, 3, 6, and 12 months postoperatively, with 31 patients (31 eyes) post-24 months above. This cohort was then compared against a normal control of 21 individuals (21 eyes). Main clinical outcomes included lipid layer thickness (LLT), blink counts and partial blink rate (PBR) measured by Lipiview interferometer, in vivo confocal microscopy (IVCM) was used to detect the density of epithelial wing cells, leukocytes, subbasal dendritic cells (DCs) and endothelial cells.
Results: Compared with normal control, LLT was decreased at 6 months (P = 0.053); total blink counts were significantly higher at 36 months (P < 0.05) after DMEK, while LLT was significantly lower (P < 0.05). Utilizing IVCM, an increased leukocytes density was identified in CED patients, which correlated positively with Log MAR visual acuity (r = 0.261, P = 0.04) and inversely with epithelial wing cells density (r = − 0.319, P = 0.009). Leukocytes density decreased to comparable level at postoperative 3 months (P = 0.11). Subbasal DCs density was still higher at 6 months postoperatively (P < 0.05), while there was no difference at 12 months after DMEK (P > 0.05).
Conclusion: Abnormalities of LLT can occur at different stages after DMEK. Besides, the immune reaction on cornea is still active within 6 months after DMEK.
Plain Language Summary: 
Plain Language Summary: What is already known on this topic:
DMEK had earned a reputation for its significantly reduced complication rates and lower incidence of graft rejection when compared to other forms of corneal transplantation.
What this study adds: Following DMEK, abnormalities in the LLT could emerge, and the immune response within the cornea remained active.
How this study might affect research, practice or policy: The study serves as a reminder to clinical doctors to closely monitor for postoperative corneal inflammation within first six months following DMEK, and to be vigilant about potential meibomian gland dysfunction during long-term follow-up periods.

Keywords: Descemet’s membrane endothelial keratoplasty, lipid layer thickness, blinking, corneal inflammatory cells