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Cataracts

** A cataract is a progressive clouding of the eye’s natural lens that blurs vision, reduces quality of life, and remains the leading cause of global blindness. **CONTENT:** ## Overview A **cataract** is a cloudy or opacified area within the crystalline **lens** of the eye that interferes with the passage of light to the retina, producing a gradual decline in visual acuity. Most cataracts develop slowly over years and may affect one eye, both eyes, or alternate between them. Early symptoms often include **faded colours**, **blurry or double vision**, and **halos around lights**, especially at night. As the opacity progresses, patients may experience increased glare, difficulty reading, trouble recognizing faces, and a heightened risk of falls or depression due to reduced independence. The condition is primarily age‑related, but it can also arise from trauma, prolonged exposure to ultraviolet (UV) radiation, certain medications (e.g., corticosteroids), metabolic diseases such as diabetes, and genetic disorders. While cataracts are not painful, they can severely impair daily activities such as driving, reading, and navigating stairs. Prompt evaluation by an eye care professional is essential when vision changes suddenly, become markedly worse, or are accompanied by pain, redness, or flashes of light, as these may signal complications like **lens dislocation** or **secondary glaucoma**. ## History/Background The word “cataract” derives from the Greek *kataraktes*, meaning “waterfall,” reflecting the ancient belief that the condition caused a “waterfall” of fluid to obscure vision. Early descriptions appear in the writings of Hippocrates (5th century BC) and Galen, who noted cloudiness of the lens. The first successful extraction of a cataract—known as **couching**—was performed in ancient India around 600 BC, using a sharp instrument to displace the opaque lens into the vitreous cavity. This crude technique persisted for centuries until the 18th century, when French surgeon **J. J. Petit** introduced the **extracapsular cataract extraction (ECCE)** method, removing the lens while leaving the posterior capsule intact. A major breakthrough arrived in 1949 with **Sir Harold Ridley’s** invention of the **intra‑ocular lens (IOL)**, initially made from polymethyl methacrylate (PMMA). The first implantation in a human eye occurred in 1950, revolutionizing cataract surgery from a vision‑restoring procedure to a refractive one. Modern phacoemulsification, introduced by **Charles Kelman** in the 1960s, uses ultrasonic energy to emulsify the lens, allowing removal through a sub‑millimeter incision and rapid visual recovery. By the early 21st century, cataract surgery had become the most frequently performed elective operation worldwide. ## Key Information - **Epidemiology:** In 2020, cataracts accounted for **39.6 % of all blindness** and **28.3 % of visual impairment** globally, making them the single most common cause of blindness. Prevalence rises sharply after age 60, affecting up to 70 % of individuals in that age group. - **Risk Factors:** Age, diabetes, smoking, excessive UV exposure, long‑term steroid use, ocular trauma, and certain hereditary conditions (e.g., congenital cataracts). - **Types:** - *Nuclear sclerotic* (central lens hardening) – most common age‑related form. - *Cortical* (spokes radiating from the lens periphery) – associated with glare. - *Posterior subcapsular* (central posterior opacity) – often linked to steroid use and diabetes. - **Diagnosis:** Comprehensive eye exam with visual acuity testing, slit‑lamp biomicroscopy, and dilated fundus examination. Grading systems (e.g., LOCS III) quantify severity. - **Management:** Early stages may be monitored; visual aids (glasses, brighter lighting) can help. Definitive treatment is **cataract extraction** with IOL implantation. Modern phacoemulsification offers <10 minute surgery, <1 day postoperative recovery, and high success rates (>95 % achieving 20/40 vision or better). - **When to Seek Care:** Sudden vision loss, new pain, redness, flashes, or a marked increase in glare warrants immediate ophthalmologic evaluation to rule out complications such as **uveitis**, **retinal detachment**, or **acute angle‑closure glaucoma**. ## Significance Cataracts represent a major public health challenge because they disproportionately affect older adults, a demographic that is expanding worldwide due to increased life expectancy. The condition’s impact extends beyond visual loss; it contributes to reduced mobility, heightened fall risk, loss of independence, and mental health issues like depression. Economically, cataract‑related visual impairment imposes substantial costs on healthcare systems and societies through lost productivity and caregiving burdens. The evolution of cataract surgery—from ancient couching to modern micro‑incision phacoemulsification—exemplifies how technological innovation can transform a debilitating disease into a highly curable condition. Today, cataract surgery is not only a sight‑restoring procedure but also an opportunity for **refractive correction**, allowing patients to reduce dependence on glasses or contact lenses. Ongoing research into **laser‑assisted cataract surgery**, **premium IOLs** (e.g., multifocal, accommodating), and **pharmacologic cataract prevention** (e.g., lanosterol eye drops) promises to further enhance outcomes and accessibility, especially in low‑resource settings where cataract remains a leading cause of avoidable blindness. **INFOBOX:** - Name: Cataract (Lens Opacification) - Type: Ophthalmic disease / Vision disorder - Date: Predominantly age‑related; incidence rises after age 60 - Location: Crystalline lens of the eye (intra‑ocular) - Known For: Being the leading global cause of blindness and the most common indication for elective eye surgery **TAGS:** cataract, eye health, vision impairment, ophthalmology, aging, intra‑ocular lens, cataract surgery, public health