Night Vision Disturbances
Night Vision Disturbances (NVDs) is a new indication with no approved therapies, despite an estimated 4 million people in the United States and 7 million worldwide (Europe and Japan) affected by the condition. In dim light conditions, the pupil dilates to allow more light to enter the eye. However, because of this dilation, light also passes through the periphery of the cornea and lens. As light passes through the periphery of the eye, any imperfections or aberrations cause light to scatter before it reaches the retina. Individuals with peripheral imperfections or aberrations experience glare and streaky vision, as well as a “halo” or “starburst” effect.
Night vision disturbances are induced by a variety of causes, including night myopia, cortical cataracts, post-intraocular lens (IOL) implants, LASIK, and keratoconus. NVDs can be debilitating and interfere with a variety of everyday activities, most notably driving. The light emitted by traffic signals and other cars makes driving in dim light conditions difficult and unsafe. The effects of NVDs can be reduced or eliminated by reducing the pupil size to a smaller diameter that prevents the scattering effect without impeding the ability to see at night.
Nyxol could be a first-line treatment for night vision disturbances based on its optimal pupil reduction properties and consequent improvement in contrast sensitivity and visual performance at night and during the day. Nyxol’s alpha-1 blocking activity relaxes (i.e., inhibits contraction of) the iris dilator muscle, resulting in a smaller pupil size.
Glaucoma is a progressive, age-related disease and the leading cause of irreversible vision loss, affecting 60 million people worldwide, including 3 million people in the United States. Glaucoma is the result of increased intraocular pressure (IOP) due to a buildup of aqueous humor in the eye. Sustained elevated IOP damages the optic nerve, resulting in loss of vision and blindness.
There are currently five classes of approved glaucoma medications. U.S. spending on glaucoma medications in 2016 totaled $2.8 billion, yet almost half of patients in treatment for glaucoma do not reach normal IOP goals. Additive treatments with new mechanisms to the standard of care glaucoma drugs are needed to decrease patients’ IOP levels. Further, glaucoma is asymptomatic until the optic nerve sustains damage, which makes it critical that once it is diagnosed, patients are compliant with treatment. However, the existing approved glaucoma medications require multiple daily applications and have associated adverse effects, which often results in missed doses or noncompliance. Significant systemic safety and topical tolerability issues contribute to noncompliance.
Nyxol could be an ideal complement to polypharmacy treatment of glaucoma given its IOP-lowering, all-day effect, and improved vision performance. Nyxol uniquely works across multiple IOP-lowering pathways. The major conventional outflow pathway includes the trabecular meshwork (TM), a tissue with contractile properties and alpha-2 adrenergic receptors. The literature indicates that alpha-2 agonists contract the TM, thus Nyxol’s alpha-2 blocking property is likely to relax the TM and thus lower IOP via this major outflow pathway. The second outflow mechanism includes the uveoscleral pathway, where blocking the alpha-1 receptors increases uveoscleral outflow. Further, Nyxol is highly lipophilic, allowing depot uveal pigment absorption for improved, long-lasting efficacy.
Reversal of Mydriasis
More than 80 million comprehensive eye exams are performed each year in the United States, during which the pupils are dilated (i.e., mydriasis), increasing sensitivity to light and impairing vision for four to eight hours afterwards. Also, many mydriasis-inducing drugs cause cycloplegia, the temporary paralysis of the muscle responsible for focusing the eye on nearby objects. Mydriatic reversal after eye exams would therefore be beneficial.
Pharmacologically-induced mydriasis is achieved either by contracting the iris dilator muscle with the use of alpha adrenergic agonists (i.e., phenylephrine) or by blocking the iris sphincter muscle with the use of cholinergic antagonists (i.e., tropicamide). Typically, induced mydriasis dilates the pupil to 7-8mm, a size suitable for ophthalmic examination of the retina and other structures of the eye’s interior.
Dapiprazole, an alpha-1 antagonist, was approved by the FDA in 1990 to reverse pharmacologically-induced mydriasis and was marketed under the trade name Rev-Eyes. Rev-Eyes was withdrawn from the market for reasons other than safety and efficacy, and since then no other drug has been approved for reversal of mydriasis.
Nyxol has been shown to reduce pupil size by relaxing the iris dilator muscle in normal eyes. To counteract mydriatic drugs, Nyxol could be instilled in the eyes to rapidly reverse mydriasis, thereby relieving post-exam side effects and discomfort.
Presbyopia is an age-related condition that commonly appears in people aged 40 to 50. As the eye ages, loss of lens elasticity results in an inability to focus on nearby objects. Presbyopia affects close to 2 billion worldwide, including over 100 million people in the United States. Like glaucoma, presbyopia’s prevalence is expected to rise as the average age of the population increases over time.
Individuals with presbyopia use reading glasses, contact lenses, and in some cases, surgical interventions, but there are no currently approved drug therapies for presbyopia. There are several drawbacks to reading glasses. For example, presbyopia only affects near vision, so reading glasses must be put on and taken off throughout the day. Contact lenses for presbyopia may cause eye strain, night vision disturbances, and other side effects. Eye drops are considered to be the “holy grail” alternative to corrective devices for presbyopia.
Presbyopia is a large unmet market, where pupil aperture management such as Nyxol’s approach is an intense area of focus. Nyxol is a potential treatment alone or in combination for presbyopia, based on its ability to reduce pupil diameter and improve visual acuity. The goal is to achieve a target pinhole size, which will result in clearer near vision.