Defining the limits of upper and lower conjunctival fornix depths in a healthy Asian Chinese population.

Abstract

Background: The early detection of conjunctival fornix shortening is essential for the effective management of progressive cicatrising conjunctival diseases. Establishing a baseline reference for conjunctival scarring by determining the normative conjunctival fornix depths (FDs) allows for the measurement and monitoring of changes in the conjunctiva. This study explored anatomical variations in conjunctival FDs amongst an Asian Chinese population, providing valuable information for conjunctival fibrosis assessment.

Methods: This retrospective study conducted at a single centre included 295 Chinese individuals (590 eyes) with normal conjunctiva who visited the eye clinic between 2019 and 2023. The lower and upper FDs were assessed using a validated FD measurer (FDM). Mean lower and upper FDs were calculated and stratified by age and gender.

Results: The mean upper and lower conjunctival FDs for the Chinese population in Singapore were 16.1 mm ± 1.6 (95% CI, 15.9-16.2) and 10.1 mm ± 1.7 (95% CI, 10.0-10.3), respectively. Females exhibited shorter FDs (upper 15.7 mm ± 1.5; lower 9.8 mm ± 1.5) compared to males (upper 16.5 mm ± 1.5; lower 10.5 mm ± 1.9) (p < 0.001). Linear regression analysis demonstrated a significant inverse correlation between age and FDs, indicating that FDs decreases with advancing age (R² = 0.1469 for upper and 0.3195 for lower fornices; p < 0.001). Specifically, the mean upper FD ranged from 17.4 mm (95% CI, 17.2-17.7) in the 20-29 age group to 15.2 mm (95% CI, 14.9-15.5) in the 80-89 age group. Similarly, the mean lower FD ranged from 12.0 mm (95% CI, 11.6-12.4) in the 20-29 age group to 8.7 mm (95% CI, 8.5-9.0) in the 80-89 age group. Analysis of the 95% CIs revealed no statistical difference in FD measurements when compared to published Caucasians, South Asians, and Turkish populations.

Conclusions: This study adds to the available literature a set of normative data for upper and lower FD in a Chinese population, highlighting gender-related variations and age-related progressive conjunctival shrinkage. The established dataset serves as a valuable resource for clinicians, enabling them to better manage and monitor patients with conjunctival diseases. These normative values in forniceal depths adds to available data obtained from Caucasian, South Asian, and Turkish eyes. Existing clinical assessment tools incorporating FD measurements, but validated in other ethnic populations, can be used in Chinese populations.