Abstract
Purpose: :
To dynamically evaluate contact lens movement and its interaction with blinking and ocular surface using ultra-high resolution optical coherence tomography (UHR-OCT).
Methods: :
A custom built spectral-domain OCT with ultra-high resolution (~3 µm) was used to image the edge of the contact lens on the eye. Primary and extreme gazes were evaluated. The inferior lens edge was imaged continuously during blinking. The lens edge was tracked to yield the movement footprint before and after blinking. The landmark was used as the ending of the Bowman’s layer at the limbus for calculating the lens edge location. Eight different types of contact lenses with different materials and lens designs (Proclear, Biofinity, Avaira, Enfilcon, Optix, two investigative lenses, CooperVision; Acuvue Advance, Vistakon) were evaluated in this pilot study.
Results: :
The lens movement between primary and extreme gazes on the horizontal meridian was 0.605 ± 0.281 mm. The lens movement was 0.829 ± 0.930 mm after a full blinking on the vertical meridian. The dynamic tracking on the vertical meridian showed a little lowering of the lens at the beginning of blinking and up to about 0.8 mm lifting after the blink. During the eye opening period, the lens was dropping with first fast phase (about 0.2 second) then a slow phase till reaching the baseline. The maximum movement was about 2.4mm in some lenses and the minimum movement was about 0.2mm in the others. The conjunctival coverage around the lens edge was found different between gazes and before and after blinking. In general, more coverage of the conjunctiva on the lens edge was found with more lens de-centeration on the eye.
Conclusions: :
We have demonstrated the feasibility of dynamic evaluation of the lens movement and de-centration with blinking and gaze. Apparent differences of interaction between lens edge and ocular surface were evident. Further studies will be investigating these observed parameters in lens fitting performance. (This study was supported by an unrestricted grant by CooperVision).
Keywords: contact lens • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: non-clinical