Novel Poly(vinylpyrrolidone)-Coated Silicone Contact Lenses to Improve Tear Volume During Lens Wear: In Vitro and In Vivo Studies

Poly(vinylpyrrolidone) (PVP-K90) is widely used to manage dry eye syndrome (DES). The marketed eye drop solutions (high dose) need frequent instillation, affecting the routine lifestyle of patients. PVP-K90-laden contact lenses can be used to overcome the limitations of eye drop solutions (low bioavailability and frequent instillation). However, the conventional methods of PVP-K90 loading show poor loading capacity and short duration of effect. In the present study, we have developed PVP-K90-coated contact lenses via a short curing approach to increase the PVP-K90 loading capacity with a sustained release profile to manage dry eye syndrome. PVP-K90 was loaded by a soaking method (SM-PVP), direct loading (during fabrication, DL-PVP), a combination of soaking and direct loading (DL-SM-PVP), and a novel coating process (SM-PVP-C and DL-SM-PVP-C). The swelling studies suggested improvement in the water uptake (hydration) property of the contact lenses due to the presence of PVP-K90. The optical transparency was within an acceptable range. The in vitro release of PVP-K90 was in the following order: PVP-coated contact lens (168 h) > DL-SM-PVP (168 h) > DL-PVP (96 h) > SM-PVP (72-96 h). PVP-coated contact lenses showed a high burst effect (lubricating effect) and sustained release (3161-448 ng/h between 24 and 168 h) due to high PVP loading/coating in comparison to the uncoated respective contact lenses (964-113 ng/h between 24 and 96 h). In animal studies, the PVP-K90-coated contact lens showed higher tear volume in comparison to the respective uncoated contact lenses and an eye drop solution. This study demonstrates a novel approach of coating a high amount of PVP-K90 on contact lenses for sustained release to manage several ocular diseases like dry eye syndrome, conjunctivitis, and other ocular injuries.