Abstract
Purpose: :
Keratoconjunctivitis sicca (KCS) is a multifactorial disease that affects the ocular surface and tear film integrity. Commonly known as dry eye, KCS is prevalent in post-menopausal women. Ovariectomized non-human primates (NHP) have many postmenopausal symptoms and may present with dry eye and, therefore, accurately mimic human KCS. In this study, ovariectomized NHP were evaluated for KCS including the presence of lacritin, an endogenous secretogogue.
Methods: :
Cynomolgus macaque (NHP), were evaluated approximately 6 months following unilateral or bilateral ovariectomy. Following ketamine sedation, biomicroscopy by slit-lamp was performed before unstimulated tear collection. Proparacaine (0.5%) was applied 10 min prior to tear collection. Polyester wicks were placed in the inferior sulcus for 1 min. To measure tear flow, wicks were weighed before and after tear collection, the difference is expressed as tear flow in milligrams. Tears were eluted from wicks with PBS for determination of lacritin content by western blot analysis. TBUT in seconds was measured using fluorescein. Data are expressed as a mean ± SEM.
Results: :
TBUT of unilateral (n=5) and bilateral (n=6) ovariectomized NHP were similar, 6±0.8 sec and 5±0.6 sec respectively (p=0.4) but both were significantly decreased compared to normal NHP, 11±0.4 sec (p<0.001, n=6). Tear flow in the bilateral ovariectomized NHP, 2±0.5 mg, was less than unilateral ovariectomized NHP 3±0.1 mg, or normal NHP, 3±0.1 mg (p=0.2). No signs of ocular irritation or inflammation were identified by slit lamp examination. Preliminary western blot results identified a strong presence of lacritin in both ovariectomized and normal NHP, quantitative analysis is ongoing.
Conclusions: :
TBUT was compromised in both ovariectomized groups and is often pathognomic of human KCS. Among the ovariectomized groups, bilateral ovariectomy compromised tear flow. Tear collection with polyester wicks is easier than Schirmer strips or capillary tubes. Tears can be readily eluted from the wicks with PBS and centrifugation, permitting measurement of both tear flow and content from the same sample.
Keywords: cornea: tears/tear film/dry eye