Cataracts in the context of "Aging-associated diseases"

Ophthalmology was one of the foremost branches in medieval Islamic medicine. The oculist or kahhal (کحال), a somewhat despised professional in Galen's time, was an honored member of the medical profession by the Abbasid period, occupying a unique place in royal households. Medieval Islamic scientists (unlike their classical predecessors) considered it normal to combine theory and practice, including the crafting of precise instruments, and therefore found it natural to combine the study of the eye with the practical application of that knowledge. The specialized instruments used in their operations ran into scores. Innovations such as the "injection syringe", a hollow needle, invented by Ammar ibn Ali of Mosul, which was used for the extraction by suction of soft cataracts, were quite common.

Muslim physicians described such conditions as pannus, glaucoma (described as "headache of the pupil"), phlyctenulae, and operations on the conjunctiva. They were the first to use the words "retina" and "cataract".

Rubella, also known as German measles or three-day measles, is an infection caused by the rubella virus. This disease is often mild, with half of people not realizing that they are infected. A rash may start around two weeks after exposure and last for three days. It usually starts on the face and spreads to the rest of the body. The rash is sometimes itchy and is not as bright as that of measles. Swollen lymph nodes are common and may last a few weeks. A fever, sore throat, and fatigue may also occur. Joint pain is common in adults. Complications may include bleeding problems, testicular swelling, encephalitis, and inflammation of nerves. Infection during early pregnancy may result in a miscarriage or a child born with congenital rubella syndrome (CRS). Symptoms of CRS manifest as problems with the eyes such as cataracts, deafness, as well as affecting the heart and brain. Problems are rare after the 20th week of pregnancy.

Rubella is usually spread from one person to the next through the air via coughs of people who are infected. People are infectious during the week before and after the appearance of the rash. Babies with CRS may spread the virus for more than a year. Only humans are infected. Insects do not spread the disease. Once recovered, people are immune to future infections. Testing is available that can verify immunity. Diagnosis is confirmed by finding the virus in the blood, throat, or urine. Testing the blood for antibodies may also be useful.

Congenital cataracts are a lens opacity that is present at birth. Congenital cataracts occur in a broad range of severity. Some lens opacities do not progress and are visually insignificant, others can produce profound visual impairment.

Congenital cataracts may be unilateral or bilateral. They can be classified by morphology, presumed or defined genetic cause, presence of specific metabolic disorders, or associated ocular anomalies or systemic findings.

Exposure of skin to ultraviolet radiation from sunlight presents both positive and negative health effects. On the positive side, UV exposure enables the synthesis of vitamin D₃, which is essential for bone health and potentially plays a role in inhibiting certain cancers. While vitamin D can also be obtained through dietary supplements, UV exposure offers benefits such as enhanced subdermal nitric oxide production and improved endorphin levels, which are not achievable through supplementation alone. Additionally, exposure to visible light supports melatonin synthesis, maintains circadian rhythms, and reduces the risk of seasonal affective disorder.

However, UV radiation is also a mutagen and carcinogen for the skin, posing significant risks. Acute exposure can lead to painful sunburns and increase the likelihood of developing serious skin conditions later in life. Prolonged exposure is associated with the development of skin cancers, photoaging or premature skin aging, immune suppression, and eye diseases like cataracts.