Abstract
Purpose :
To characterize central corneal thickness (CCT), tear osmolarity and blink rate longitudinally in a non-human primate (NHP) model, the common marmoset (Callithrix Jacchus), in untreated compared to animals treated with contact lenses (CL).
Methods :
Longitudinal changes in CCT (N=20; 10CL), osmolarity (N=10; 6CL) and blink rate (N=18; 10CL) were assessed using high frequency A-scan ultrasound (25 MHz, Panametrics, NDT), I-PEN Vet Tear Osmolarity System (I-MED Pharma Inc), and a video recording system (745 frames/minute) from 70 days to 150 days (5 months) at approx. 9am, and again after 9hrs of CL wear (methafilcon A, 55% water content; Capricornia, Australia). Data was assessed for normality. Repeated measures ANOVA and student T-test were used to compare treated to control eyes over time.
Results :
At baseline, untreated marmosets had a mean±SD CCT of 0.305±0.008 mm, osmolarity 311.67±11.48 mOsms/L and blink rate 1.83±1.79 blinks per minute (bpm), which remained stable over 5 months, except blink rate that increased to 5.32±1.58 bpm (p<0.01) after 5 months. In CL-treated marmosets, CCT increased during the second month of CL wear (baseline: 0.299±0.007 mm; 2 months: 0.307±0.008 mm, p<0.05) and stabilized afterwards. Osmolarity progressively decreased after 2, 3 and 4 months of CL wear (baseline: 316.11±13.63; 2 months: 302.63±11.27, p<0.05; 3 months: 302.92±14.58, p<0.05; 4 months: 301.50±12.90, p<0.05). This longitudinal decrease in osmolarity occurred in parallel to an increase in blink rate (baseline: 0.98±1.18 bpm; 1 month: 2.58±2.50 bpm, p<0.05; 2 months: 3.46±3.04 bpm, p<0.05; 3 months: 3.73±1.50 bpm, p<0.001), which later decreased after 4 months (2.11±1.49 bpm, p<0.05).
Conclusions :
Juvenile untreated marmosets exhibit CCT, osmolarity and blink rates that remain stable from 2 to 7 months of age, except blink rate that increased at 7 months of age. Marmosets treated with CL for 5 months, however, experienced an increase in blink rate and CCT, along with a decrease in osmolarity within the first 3 months of CL treatment. We hypothesize that CL wear might be inducing mild corneal edema and an increased blink rate, in turn delaying the development of hyperosmolarity. These findings support the marmoset as a new animal model for ocular surface research, and its potential to assess CLIDEM.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.