Cataract and Cataract Surgical Coverage
Ching-Yu Cheng, Tien Yin Wong in Ophthalmic Epidemiology, 2022
The human lens is an optically clear structure that lies between the iris and the vitreous body of the eye. It is transparent, biconvex, composed of lens fibers, and surrounded by capsule. The lens is supported by zonules on either side. The nucleus of the lens is made up of older lens fibers, while newer fibers are located in the cortex at the outer layers of the lens. The clear lens focuses light rays on the retina, while providing accommodation and maintaining its own clarity. Cataract occurs when the lens loses its optical clarity for any reason and becomes opacified. Specifically, cataracts are defined as lens opacities associated with some degree of visual impairment.1 Lens opacity is a direct result of oxidative stress.2 There are different causes of cataract, but by far the most common is aging. Other causes include congenital and developmental factors, trauma, various ocular and metabolic diseases, radiation of different kinds, allergic dermatitis, and medications.
The nervous system and the eye
C. Simon Herrington in Muir's Textbook of Pathology, 2020
The biconvex lens substance is formed by cells that contain transparent crystalline lens proteins. A cataract is any opacity of the crystalline lens. The cells of the lens are enclosed in an elastic membrane, the lens capsule. Metabolism of the lens is maintained by diffusion of nutrients from the aqueous. Any change in the biochemical composition of the aqueous fluid, as occurs in metabolic diseases, e.g. diabetes mellitus or hypocalcaemia, may result in the formation of abnormal opaque proteins in the damaged lens cells. Other insults such as uveitis, ionizing radiation, or trauma may also result in opacities. Congenital cataracts may form if there is damage to the developing lens fibres in utero, e.g. as a result of rubella infection. The most common form of cataract, however, is senile cataract, which is due to the degradation of lens proteins in the oldest, central part of the lens. Most cases of cataract are treated by removal of the opaque lens matter by ‘phakoemulsification’ and the insertion of a plastic lens implant into the residue of the lens capsule behind the iris.
Primary care resource centres – a means of supporting general practice?
Pat Gordon, Janet Hadley, Pat Gordon, Diane Plamping in Extending Primary Care, 2018
Two per cent of 60-year-olds and over 40% of those over 80 years of age suffer from senile cataract. In an area of 10-15 GPs with a population of 20-30 000 people, one would expect 700 people with cataracts sufficiently severe to disturb their eyesight, and between 70-90 people developing cataract for the first time each year. Glaucoma probably affects about 70 people in this GP area (0.5% of people aged between 55-60 and over 4% of those over 80 years). About a quarter of these have other affected family members and can therefore be identified as high risk and entitled to free eye testing. The loss of vision caused by glaucoma can be reduced by early detection and treatment. GPs, optometrists and ophthalmologists working together can achieve this.
The Pulfrich Phenomenon: Practical Implications of the Assessment of Cases and Effectiveness of Treatment
Published in Neuro-Ophthalmology, 2018
Jane Farr, Emily McGarva, Jenny Nij Bijvank, Hans van Vliet, Hinke Marijke Jellema, Michael D. Crossland, Axel Petzold
The Pulfrich phenomenon gives rise to symptoms that can be disturbing and cause difficulties with tasks involving judgement of moving objects, such as playing certain sports, crossing roads or driving.6 Conditions which have previously been found to elicit these symptoms include optic neuritis, cataract and anisocoria.5,13 It has been reported that the Pulfrich phenomenon can be managed with a tinted lens in front of the better eye, for example with the use of uniocular tinted spectacles or a tinted contact lens.13 The principle behind this being that the retinal illumination reduction from the tinted lens or filter in the better eye counteracts the disparity from the other eye. Here, we revisit the effect of a monocular ND filter as a management option for patients presenting with symptoms of the Pulfrich phenomenon.
An approach to revolutionize cataract treatment by enhancing drug probing through intraocular cell line
Published in Libyan Journal of Medicine, 2018
Ling Wang, Weixian Liu, Xionggao Huang
Eye is an intricate organ isolated by blood–ocular barriers which includes retinal, aqueous and vitreous humor making it a primary and accessible site for drug delivery investigations [1]. The main way of administering a drug for any eye disorder is ophthalmic application but the conventional formulations ensure only a limited amount of drug penetrating these barriers. Although eye is generally protected, but still problems relating to age like cataract frequently surface and treatment of cataract generally leads to a single outcome – surgery [2] and intravitreal procedures associated with numerous side effects like detachment of retina [3]. Cataract may be the chief cause of blindness in 50% of cases worldwide. The principal cause of cataract is ageing and frequently other associated factors may be exogenous like UV radiation and trauma causing accidents or endogenous like diabetes and genetics [2]. Surgery has been the most established and effective treatment for reversing cataract except for the fact that this requires medical expertise and instrumentation. These two factors are limiting since they are not available everywhere. Hence there is an immediate need for non-invasive techniques for treatment and reversal of cataract.
The Impact of Sociodemographic and Socioeconomic Factors on the Burden of Cataract in Small Island Developing States (SIDS) in the Caribbean from 1990 to 2016
Published in Ophthalmic Epidemiology, 2020
Ebiakpo-Aboere Sonron, Vrijesh Tripathi, Seetharaman Hariharan
As age increases, so does the risk of cataract.30 It has been reported that of all the people who suffer from blindness, an estimated 82 per cent are aged over 50 years, with cataract being the leading cause of blindness.31 There are older large population-based studies that found that the proportion of those who lost their vision due to age-related cataract was greater for those older than 74 years.32–35 The findings of a significant difference in crude rates across the age groups is consistent with the expectation that the burden of cataract would be greater as age increases. For people living with moderate and severe visual impairment, it is said that 28 per cent are in their working years.31 This is important to note as the sex-specific cataract burden by age shows that men have higher crude rates after the age of 45 years. In 2016, the life expectancy for men of the countries of this study ranged from 61 to 74 years,13 which means the cataract burden brings limitations of productivity as it impacts a great portion of their working years.
Related Knowledge Centers
- Congenital Cataract
- Diplopia
- Eye
- Nyctalopia
- Visual Impairment
- Lens
- Falling
- Depression
- Senescence
- Injury