CONTROLLING LENS INDUCED MYOPIA IN CHICKENS WITH PERIPHERAL LENS DESIGN

Sarah Guthrie

Abstract

PURPOSE: To determine if lens induced myopia in chickens can be inhibited with a minus power lens that is combined with a unique hyperopic peripheral lens design aimed at myopia progression control (MPC).

METHODS: Thirty-six newly hatched chicks were fit unilaterally with lenses attached by Velcro™. Chicks were fitted with an extended depth of focus MPC test lens of central power -10.00D (T1; n=14), a lower depth of focus design MPC test lens of central power -10.00D (T2; n=6) and a spherical -10.00D control lens (Control; n=16). Refractive error was measured using streak retinoscopy on days 0, 3, 7, 10 and 14. Axial lengths (cornea to retina) were measured on a subset of chicks using high frequency A-scan ultrasonography on days 0 and 14.

RESULTS: Results are reported as mean differences between treated and untreated eyes (MDiffref, MDiffaxial). MDiffref was insignificant between groups on day 0 (all p>0.99). By day 3, the MDiffref of T1 (+1.36D) and T2 (-2.33D) were statistically different from that of the Control group (-5.84D) (both p<0.01). The MDiffref after 7 days (T1:+2.29D,T2:-2.00D, Control:-8.44D), 10 days (T1:+3.18D, T2:-1.75D, Control:-8.06D) and 14 days (T1:+4.57D, T2:-1.75D, Control:-7.47D) were statistically different between the Control group and each Test group (all p<0.01). Axial lengths on day 0 were not different between treated and untreated eyes for all groups (n=24, all p>0.99). Axial length was unchanged over the study period in both Test groups (both p>0.99), yet changed significantly in the Control group (p<0.01). On day 14, MDiffaxial were statistically different between the Control group (0.64mm, n=11) and each test group (T1:0.04mm, n=7; T2:0.11mm, n=6; both p<0.01).

CONCLUSIONS: These results indicate that lens-induced myopia in chickens can be significantly affected by these two unique lens designs and support the role of peripheral retinal focus influencing eye growth.

ADDITIONAL COMMENTS: This study was supported by Visioneering Technologies Inc (US6474814(B1),US7178918(B2))

Details

Year: 2011

Program Number: 110421

Author Affiliation: University of Waterloo, Centre for Contact Lens Research

Co-Authors: Jill Woods, Nancy Keir, Sally Dillehay, Mark Tyson, Richard Griffin, Desmond Fonn, Lyndon Jones, Elizabeth Irving

Co-Author Affiliation: University of Waterloo, Centre for Contact Lens Research, University of Waterloo, Centre for Contact Lens Research, Visioneering Technologies Inc., Visioneering Technologies Inc., Visioneering Technologies Inc., University of Waterloo, Centre for Contact Lens Research, University of Waterloo, Centre for Contact Lens Research, University of Waterloo, School of Optometry and Vision Science

Room: Room 208