by Mark Steedman, PhD
This week is World Glaucoma Week, aimed at raising awareness around glaucoma – a group of eye diseases that lead to damage to the optic nerve and can cause permanent vision loss. World Glaucoma Week encourages people to have regular eye checks to detect glaucoma (and other eye diseases) early and pursue treatment to preserve their vision.1
The human eye is a fascinatingly complex organ. Light enters through the cornea, passes through the pupil and lens and is focused on the retina, which contains light-sensitive cells that convert photons into electrical signals. These signals are transmitted to the brain via the optic nerve, where they are translated into the images a person sees. This extremely sensitive process allows humans to differentiate between approximately 10 million colours2 and potentially detect a single photon of light.3
However, a number of diseases can affect these processes, leading to poor vision or even blindness, which can drastically impact psyche and quality of life. A 2016 study found blindness to be what many people fear most – as much as or more so than losing hearing, memory, speech or a limb.4 Despite the magnitude of this fear, visual impairment is still a major public health concern worldwide, especially for middle-aged and elderly adults. Research on the global scale of vision loss in 2015 estimated that 36 million people were blind and 217 million people had moderate or severe vision impairment.5
My own interest in eye health goes back many years, linked to the research I did for my PhD that focused on diseases that affect the retina, such as age-related macular degeneration and retinitis pigmentosa. In these diseases, irreplaceable cells in the retina die, resulting in degeneration of the surrounding retina tissue, eventually leading to blindness.
Glaucoma, on the other hand, results in degeneration of the optic nerve. The main risk factor for glaucoma is elevated pressure in the eye (intraocular), although not all types of glaucoma are characterised by higher than normal intraocular pressure. In the most common form of glaucoma, known as primary open-angle glaucoma, drainage canals in the eye slowly clog over time, leading to increased eye pressure and damage to the optic nerve. This damage gradually leads to loss of the visual field, starting with the peripheral vision, and if untreated can eventually lead to blindness.
Currently in the UK, it is estimated that approximately 480,000 people have primary open-angle glaucoma.6 However, numerous treatments are available, including:
- eye drops that lower intraocular pressure
- laser treatment to open up blocked drainage tubes or reduce the production of fluid in the eye
- and surgery to improve the drainage of fluid.7
Although glaucoma is currently incurable, it generally takes many years for symptoms to develop, making routine eye tests an important part of normal health care, as early diagnosis and treatment can help stop progression of the disease. However, like most trends in visual impairment, the burden of disease of glaucoma disproportionately affect low and middle-income countries (LMICs).
Glaucoma is the world’s third leading cause of blindness, after cataracts and uncorrected refractive error. All of these causes are readily treatable, although the availability and accessibility of treatment around the world is highly variable. In 2015, an estimated 2.9 million people were blind due to glaucoma and a further 4.0 million people had moderate or severe vision impairment due to glaucoma.8 Yet, there are many reasons for governments to invest in glaucoma treatments. Eye health interventions often lead to large financial return-on-investments (ROI) to societies, largely because the individuals who are treated remain in or return to the workforce. One study found that open-angle glaucoma therapy results in a 4000 per cent ROI, and cataract surgery has a 4500 per cent ROI, both of which would add to the country’s Gross Domestic Product and increase the wealth of a nation.9 These calculations took into account:
- direct ophthalmic medical costs expended (hospital, physician, drug, diagnostic testing and so forth)
- direct medical costs saved (decreased costs for depression, injury, skilled nursing facility, nursing home and others)
- direct non-medical costs saved (decreased costs for caregivers, transportation, residence costs, moving costs, and others)
- and indirect medical costs saved (improving employment incidence and wages).
In high-income countries, the burden of disease is much lower, as numerous treatments are both available and accessible to local populations, resulting in relatively low levels of unmet need.
However, one area in need of improvement in high-income countries is patient adherence, as topical treatments such as eye drops often require multiple applications per day. According to a recent report, at least two sustained-release implants will help alleviate this unmet need.10 Other products in development that are expected to impact the glaucoma market include a first-in-class drug, a drug with an undisclosed mechanism of action and a combination therapy. Together, these five products are expected to grow the total glaucoma market across the US, France, Germany, Italy, Spain, UK and Japan to $3.8 billion in 2026, up from $2.6 billion in 2016, and corresponding to a compound annual growth rate of 4.1 per cent.11
Despite efforts to close the gap in recent years, the disparity in eye health between high-income and LMICs remains sizeable, and there remains a large unmet need for access to routine eye tests and glaucoma treatment in much of the world. Moreover, there is ample opportunity to improve access to treatments through a coordinated effort of political and financial commitment, capacity building and training of eye care professionals.
Similarly, innovation in high-income countries that leads to improvements in patient adherence could eventually become affordable in LMICs, helping to alleviate the burden of glaucoma. New technological advances, such as novel microdevices combined with therapies to prevent scarring have the potential to lower pressure to levels associated with minimal disease worsening. This could change the paradigm of glaucoma management in the future.
Over the next few months, the Centre for Health Solutions will be working with Professor Sir Peng T. Khaw, Consultant Ophthalmic Surgeon at Moorfields Eye Hospital and University College London, and other global eye health experts to prepare a report on glaucoma and other eye diseases as part of the Eye Health Forum for the 2018 World Innovation Summit for Health (WISH), which will be held at Qatar National Convention Centre on 13th-14th November 2018.
1 About World Glaucoma Week. World Glaucoma Week, 12 March 2018. See also: https://www.wgweek.net/about-world-glaucoma-week/
2 Judd DB, Wyszecki G. Color in Business, Science and Industry. Wiley Series in Pure and Applied Optics (3rd ed.) New York: Wiley-Interscience. P. 388.
3 Conover E. Human eye spots single photos. Science News, 2016. See also: https://www.sciencenews.org/article/human-eye-spots-single-photons
4 Preidt R. Blindness biggest fear for many Americans. WebMD. 4 August 2016. See also: https://www.webmd.com/eye-health/news/20160804/blindness-biggest-fear-for-many-americans
5 Sabanayagam C and Cheng CY. Global causes of vision loss in 2015: are we on track to achieve the Vision 2020 target? The Lancet Global Health. 5(12):e1164-5. Epub 11 October 2017. See also: http://www.thelancet.com/journals/langlo/article/PIIS2214-109X(17)30412-6/fulltext
6 Glaucoma. Moorfields Eye Hospital NHS Foundation Trust. 12 March 2018. See also: https://www.moorfields.nhs.uk/condition/glaucoma
7 Glaucoma. NHS choices. 12 March 2018. See also: https://www.nhs.uk/conditions/glaucoma/
8 Flaxman SR et al. Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis. Lancet Global Health, 5(12):e1221-e1234. Epub 11 October 2017. See also: http://www.thelancet.com/journals/langlo/article/PIIS2214-109X(17)30393-5/fulltext
9 Brown MM et al. Financial return-on-investment of ophthalmic interventions: a new paradigm. Curr Opin Ophthalmol, 25(3):171-6. May 2014. See also: https://www.ncbi.nlm.nih.gov/pubmed/24638114
10 Global glaucoma market to reach $3.8 billion by 2026. GlobalData Healthcare. 1 February 2018. See also: https://www.globaldata.com/global-glaucoma-market-reach-3-8bn-2026/