Myopia has been increasing rapidly throughout the developed world, suggesting environmental factors are involved.A single-author literature review in 2021 proposed that myopia is the result of corrective lenses interfering with emmetropization. Genetics
A risk for myopia may be inherited from ones parents. Genetic linkage studies have identified 18 possible loci on 15 different chromosomes that are associated with myopia, but none of these loci is part of the candidate genes that cause myopia. Instead of a simple one-gene locus controlling the onset of myopia, a complex interaction of many mutated proteins acting in concert may be the cause. Instead of myopia being caused by a defect in a structural protein, defects in the control of these structural proteins might be the actual cause of myopia. A collaboration of all myopia studies worldwide identified 16 new loci for refractive error in individuals of European ancestry, of which 8 were shared with Asians. The new loci include candidate genes with functions in neurotransmission, ion transport, retinoic acid metabolism, extracellular matrix remodeling and eye development. The carriers of the high-risk genes have a tenfold increased risk of myopia. Aberrant genetic recombination and gene splicing in the OPNLW1 and OPNMW1 genes that code for two retinal cone photopigment proteins can produce high myopia by interfering with refractive development of the eye.Human population studies suggest that contribution of genetic factors accounts for 60–90% of variance in refraction.
Labetalol is a medication used to treat high blood pressure and in long term management of angina. This includes essential hypertension, hypertensive emergencies, and hypertension of pregnancy. In essential hypertension it is generally less preferred than a number of other blood pressure medications. It can be given by mouth or by injection into a vein.Common side effects include low blood pressure with standing, dizziness, feeling tired, and nausea. Serious side effects may include low blood pressure, liver problems, heart failure, and bronchospasm. Use appears safe in the latter part of pregnancy and it is not expected to cause problems during breastfeeding. It works by blocking the activation of β-receptors and α-receptors.Labetalol was patented in 1966 and came into medical use in 1977. It is available as a generic medication. In 2019, it was the 198th most commonly prescribed medication in the United States, with more than 2 million prescriptions. Medical uses
Labetalol is effective in the management of hypertensive emergencies, postoperative hypertension, pheochromocytoma-associated hypertension, and rebound hypertension from beta blocker withdrawal.It has a particular indication in the treatment of pregnancy-induced hypertension which is commonly associated with pre-eclampsia.It is also used as an alternative in the treatment of severe hypertension. Special populations
Pregnancy: studies in lab animals showed no harm to the baby. However, a comparable well-controlled study has not been performed in pregnant women.Nursing: breast milk has been shown to contain small amounts of labetalol (0.004% original dose).