Ocular Bandage Gel (CMHA-S platform)

Photorefractive keratectomy

Photorefractive keratectomy (PRK) is an efficacious alternative to laser in situ keratomileusis (LASIK) for the correction of refractive errors. It involves controlled mechanical removal of corneal epithelium with subsequent excimer laser photoablation of the underlying Bowman’s layer and anterior stroma, including the subepithelial nerve plexus (Tomás-Juan 2015).  Ablation of the corneal nerve plexus can result in diminished corneal sensation, leading to decreased rate of epithelial mitosis, slow wound remodeling, and diminished tear flow (Belmonte 2004, Martin 1988, Pérez-Santonja 1999). Following PRK, corneal sensation may not return to pre-operative levels for one to three months, and on average takes 3.5 to 4 days to close with a bandage contact lens (BCL) (Belmonte 2004, Martin 1988, Pérez-Santonja 1999, Tomás-Juan 2015, Taneri 2016). Although this procedure yields desirable visual acuity results, common complications of the procedure related to the epithelial defect may include post-operative pain, risk of corneal infection, corneal haze formation, decreased contrast sensitivity, and slower visual recovery (Alió 1998, Ben-Sira 1997, Loewenstein 1997, Lohmann 1991).

Wound closure and management is critical for successful refractive surgery and, for PRK, the first step is repair of the epithelium (Tomás-Juan 2015).  Therefore, enabling the epithelium to heal faster may mitigate the immediate post-operative complications thus hastening visual recovery and outcomes. Whether created intentionally during surgery and/or as a result of poor re-epithelialization from an underlying etiology, the treatment goal for all epithelial defects is to ensure protection and management so that full closure occurs as soon as possible to improve vision, reduce pain and infections, and to improve outcomes (Durrie 2018).

Current treatments often fall short in protecting the cornea and reducing staining. Artificial tears have limited residence time and generally provide only limited protection of the cornea and ocular surface.  Ointments and gels, while offering better residence time than artificial tears are generally thick and blur vision, thus making them less useful for daytime use. Bandage contact lenses (BCLs) have been associated with recurrent epithelial erosions, delayed healing, increased and extended pain, and increased risk of infections (Hovanesian 2001).

Punctate Epitheliopathies

Punctate epitheliopathies (PE) are an early sign of corneal epithelial compromise and are associated with a variety and many pathologic ocular inflammatory conditions including ocular causes as well as systemic diseases (Mokhtarzadeh 2011).  Patients with PE may present with non-specific symptoms such as red eye, tearing, foreign body sensation, photophobia, and burning. The distribution of the PE can provide information regarding the underlying etiology.  Causes can include dry eye, acute and chronic bacterial and viral conjunctivitis, trauma, contact lens wear (tight lens syndrome), chemical irritation and burns, diabetic and infectious neuropathies, chemotherapy, corneal abrasion, and eyelid malposition with secondary exposure keratopathy (Mokhtarzadeh 2011).

Punctate epitheliopathies (PE) that accompany dry eye can alter the corneal surface and can affect visual quality. Furthermore, the presence of these PEs, often detected by corneal staining, are often the result of altered tear film which can cause symptoms of blur and foreign body sensation in the eye.