Abstract
Within ophthalmology, focus is ever increasing on global trends in ocular care and socioeconomic determinants of vision outcomes. Worldwide, uncorrected refractive error and cataract continue to disproportionately affect persons in low-income and middle-income countries. Increasingly, smartphone technology and artificial intelligence are impacting screening and analysis of patients with suspected conditions such as strabismus, diabetic retinopathy, and glaucoma. Building upon large-scale treatment strategies, management of leading infectious ocular conditions worldwide, such as trachoma and onchocerciasis, has yielded remarkable improvements in community health. In terms of pediatric conditions, the world is currently experiencing a “third wave” of retinopathy of prematurity, whereas retinoblastoma continues to demonstrate differences in both vision outcomes and overall survival between patients in low-income and high-income countries. Finally, many conditions which do not threaten vision remain major reasons for patients to seek care in countries of any income status.
TopIntroduction
Over a year into the ongoing COVID-19 pandemic, focus on the impact of socioeconomic determinants of health has been increasing both domestically and globally (Burström & Tao 2020). In terms of global evaluation of visual health, the World Health Organization (WHO) released a world report on vision in October 2019 which stated that a minimum 2.2 billion people worldwide have a form of vision impairment with at least 1 billion of those persons having vision impairment which was either preventable or who still are awaiting appropriate care (World Health Organization [WHO], 2019). While the COVID-19 pandemic began soon after the report was released and is still ongoing as of October 2021, delays of vision care worldwide have already been frequently reported during the pandemic (Syriga et al., 2021). Early in the pandemic, ophthalmologic surgical numbers worldwide dropped precipitously before recovering later in the year (Sanjay et al., 2021; Das & Reddy, 2021). Ultimately, it will take some time after the conclusion of the pandemic to determine the full impact of COVID-19 on the number of persons with visual impairment as compared with that listed in the WHO report released immediately prior to the pandemic.
Vision plays an integral part of our lives, beginning with its role in the early development of children, later empowering education, and enabling efficient social interaction and functioning within a career as an adult (WHO, 2019). Globally, the burden of vision impairment and other ophthalmologic conditions disproportionately affects persons from low-income countries (LIC) or middle income countries (MIC), people from rural areas, elderly persons, and region-specific underserved populations (WHO, 2019). The number of persons with ophthalmologic conditions is projected to increase substantially with the aging population globally and lifestyle changes within that population (WHO, 2019). While the reasons for LICs and MICs to lag behind high income countries (HIC) in terms of eye care are multifactorial, training of ophthalmologists remains a critical factor (Olivieri et al., 2021). Models have been proposed to increase adequate training of ophthalmologists in these countries including the model nicknamed “sandwich” training which utilizes in-person clinical training at an institution in a HIC, later transitioning students back to their respective LIC or MIC to complete their clinical training (Olivieri et al., 2021). In addition to the shortage of available ophthalmologists and ophthalmologic staff, healthcare logistical concerns remain persistent with eye care often not well integrated into a given country’s health system (WHO, 2019). Finally, financial resources allowing adequate healthcare coverage and purchase of adequate amounts of ophthalmic technology remains an unaddressed factor in eye care in many countries, as does establishing a strong primary care network for detection and appropriate referral to ophthalmology (WHO, 2019). While many of the selected ophthalmologic complaints discussed below threaten vision, several conditions which do not threaten vision are included as they are some of the most common reasons for ophthalmology visits and therefore merit discussion (WHO, 2019).
Key Terms in this Chapter
Cataract: Opacification of the crystalline lens of the eye which is most often associated with aging but can be due to a variety of etiologies.
Retinopathy of Prematurity: Damage to the retina as a result of abnormal blood vessel proliferation in newborn infants, especially prevalent for premature births requiring supplementation of oxygen.
Diabetic retinopathy: Damage to the retina as a result of injury to small blood vessels and other ocular structures secondary to diabetes mellitus. Diabetic retinopathy begins with a non-proliferative stage and can progress to a proliferative stage, with newly-formed blood vessels further damaging the retina.
Conjunctivitis: Irritation of either the bulbar or palpebral conjunctivae. Conjunctivitis may be caused by mechanical or chemical irritation, a viral or bacterial infection, trauma, or allergic reaction.
Strabismus: Misalignment between the visual axes of the two eyes to the point where binocular vision is detrimentally affected.
Trachoma: Trachoma is infection of the eye with Chlamydia trachomatis . This infection can then lead to the condition known as trichiasis, which is the scarring of the inner surface of the eyelids or inward turning of the eyelashes that results in scratching of the cornea, eventually leading to decreased vision or blindness.
Glaucoma: Abnormally elevated intraocular pressure which can lead to insidious and progressive deterioration of visual fields beginning with peripheral vision and moving centrally.
Retinoblastoma: An intraocular cancer that can be associated with extraocular sarcoma and is generally due to a mutation of the RB1 tumor suppressor gene that may be either inherited or acquired.
Onchocerciasis: A condition colloquially known as “river blindness,” onchocerciasis is the result of infection with the nematode Onchocerca volvulus via transmission by a blackfly of the Simulium genus.
Age-Related Macular Degeneration: Deterioration of central vision as a result of damage to the macula. Macular degeneration may be due to deposition of drusen within the macula (termed “dry”) or due to edema from nearby proliferation of blood vessels (termed “wet”).