Defining the Limits of Normal Conjunctival Fornix Anatomy in a Healthy South Asian Population

PURPOSE Quantifying the extent of conjunctival fibrosis for documentation of progression in conjunctival scarring disease is a clinical challenge. Measurement of forniceal foreshortening facilitates monitoring of these disorders. This study aims (1) to define the limits of the normal human conjunctival fornices and how these alter with age and (2) to provide normative data for upper and lower fornix depths (FDs) and fornix intercanthal distance (FICD) within a healthy South Asian, racially distinct population. DESIGN Epidemiologic, cross-sectional study. PARTICIPANTS A total of 240 subjects with national origins from South Asia, with no known ocular history and normal adnexal and conjunctival examination, aged 20 to 80 years. METHODS An FICD modification of a custom-designed fornix depth measurer (FDM) was validated and used for measurement of both lower and upper FDs together with FICDs in 480 healthy eyes with no ocular comorbidities. Data were analyzed using repeated-measures analysis of variance and presented as means with 95% confidence intervals (CIs). MAIN OUTCOME MEASURES Mean lower and upper FDs and FICD for the entire cohort, stratified according to age decade and sex. RESULTS For this South Asian population, the overall upper and lower FDs were 15.3 mm (95% CI, 14.9-15.6) and 10.9 mm (95% CI, 10.7-11.1), respectively, with FICD defined as 32.9 mm (95% CI, 32.5-33.4) (upper) and 31.7 mm (95% CI, 31.3-32.1) (lower). With increasing age, a progressive reduction of all measured parameters (P < 0.001) was noted, with female subjects having significantly shallower fornices (upper FD, P < 0.001; lower FD, P < 0.001; upper FICD, P = 0.081; and lower FICD, P = 0.015). CONCLUSIONS This is the first study to define the limits of normal upper FD and FICDs in any population group. Our study demonstrates sex variations and progressive conjunctival shrinkage with age. Although it provides important, objective data for normal forniceal anatomy, further study is recommended in other populations to confirm the generalizability of these data or to enable normal comparative datasets for the assessment of conjunctival scarring disorders among all anthropological groups.