A polymer based index-matching gel for use with nanostructure optical fibers is disclosed. The index-matching gel has a viscosity η at 25° C. of 3 Pa-s≦η≦100 Pa-s, which prevents the index-matching gel from wicking into the voids and down the nanostructure optical fiber to a depth where the fiber performance and/or device performance is compromised. The gel is suitable for use when mechanically splicing optical fibers when at least one of the optical fibers is a nanostructure optical fiber. The gel is also suitable for use in fiber optic connectors wherein at least one of the optical fibers constituting the connection is a nanostructure optical fiber.