Diurnal variation in comfort and end of day wettability of soft spherical and toric contact lenses

Authors
Michel Guillon¹, Rachel Marullo² , Pasquale Pepe¹, Anna Sulley³,  Percy Lazon de la Jara²
1 Ocular Technology Group International, UK
2 Coopervision, Inc., USA
3 CooperVision International Ltd, UK
 

Purpose
Contact lens comfort and its diurnal change are dependent upon design characteristics, thickness profile, material properties and surface wettability. Toric contact lenses, which incorporate orientation stability features, and spherical lenses have  different thickness profiles.  This study evaluated the effect of toric and spherical contact lenses of the same material on the comfort response and on-eye wettability.
 

Methods 
This was an interventional, prospective, open-label, investigator-masked, parallel group study.  Participants, who were habitual daily spherical and toric contact lens wearers, wore daily disposable stenfilcon A spherical (control) and toric (test) lenses for 10 hours.  Contact lens comfort was recorded monocularly on application, and after 30 minutes, 2, 4, 6, 8 and 10 hours of lens wear with a 100-point visual analogue scale (0=Not comfortable, 100=Extremely comfortable).  Contact lens surface de-wetting kinematics over 30 seconds interblink-period was measured at 10 hours; de-wetting endpoint was the overall exposed area over the interblink. 
 

Results
The test (n=20) and control (n=20) populations were matched for age (test: 25.2±4.7 years; control: 25.1±4.7 years, p=0.920), sex (female: test: 60%; control: 70%; p=0.507) and spherical refraction (test: -2.79±1.26D; control: -2.66±1.43D; p=0.679). A gamma distributed Generalized Linear Mixed Model (GLMM) analysis of comfort over the wearing period revealed no difference between lens types (test: 84.1pt; control: 83.9pt, p=0.808), similar diurnal variations (test: 88.6 to 78.1pt; control: 88.4 to 77.3, p=0.806) with a decrease of approximately 9 points between application and 10 hours wear (p<0.001). De-wetting over 30 seconds of open eye, which followed a cubic function profile, revealed no difference between lens types in overall exposed area (test: 47.3%; control: 42.9%, p=0.285).
 

Conclusions
The stenfilcon A daily disposable toric lenses achieved similar levels of comfort diurnal variation and on-eye wettability over 10 hours wear as the spherical lenses.
 

Disclosures
Study was carried out at Ocular Technology Group International supported by CooperVision, Inc.
Anna Sulley, Rachel Marullo and Percy Lazon de la Jara are employees of CooperVision.