question: How do eye drops remove the redness from eyes?
comment: They contain substances like Tetrahydrozoline which is a so-called "vasoconstrictor", which basically means "it shrinks blood vessels". If you shrink a blood vessel, it contains less blood, and is thus less visible. Do that in your eyes, and it appears as if your eye is less red.
passages: Eye drops have less of a risk of side effects than do oral medicines, and such risk can be minimized by occluding the lacrimal punctum, (i.e. pressing on the inner corner of the eye) for a short while after instilling drops. Eye drops are also used for stopping itching and redness of the eyes.
  
  Section::::Shelf life.
   BULLET::::- Use of this product can cause a rebound effect causing the redness to worsen. Prolonged use can cause blood vessels to be dilated for an extended period of time. Use should be limited unless specified by a doctor.
  
  BULLET::::- A red eye may often be indicative of more serious underlying ocular condition; simply reducing blood flow to the area won't solve the condition and may even exacerbate symptoms.
   BULLET::::- swelling of palpebral conjunctiva
  
  BULLET::::- retrotarsal folds
  
  Usually the effect of UV exposure is felt after 6-8 hours from exposure. With severe irritation, the eyes become blood red. In minor cases, avoid rubbing and wash the eyes thoroughly with water until the irritation subdues. Always consult an eye specialist as soon as possible. Medications (for minor erosion of cornea) usually involve eye drop such as Hydroxypropyl Methycellulose Ophthalmic solution USP sold under the trade name GenTeal®. (February 2019)
  
  Section::::Prevention.
   Section::::Types and uses.:Drug administration.:Pink eye.
  
  Antibiotic eye drops are prescribed when conjunctivitis is caused by bacteria but not when it is caused by a virus. In the case of allergic conjunctivitis, artificial tears can help dilute irritating allergens present in the tear film.
  
  Section::::Types and uses.:Drug administration.:Mydriatic eye drops.
  
  These make the eye's pupil widen to maximum, to let an optometrist have the best view inside the eyeball behind the iris. Afterwards in sunny weather they can cause dazzling and photophobia until the effect of the mydriatic has worn off.
   Strong red colors for eye products have been produced using the dye carmine, made from carminic acid extracted from the crushed bodies of the cochineal insect. Carmine was once the only bright red color permitted by the FDA for use around the eye.
   In October 2011, the first clinical trial was announced for the treatment of choroideremia. Dr. Robert MacLaren of the University of Oxford, who lead the trial, co-developed the treatment with Dr. Miguel Seabra of the Imperial College, London. This Phase 1/2 trial used subretinal AAV to restore the REP gene in affected patients.
  
  Initial results of the trial were reported in January 2014 as promising as all six patients had better vision.
  
  Section::::Clinical trials.:Color blindness.
   A 2007 Cochrane review on found that laser photocoagulation of new blood vessels in the choroid outside of the fovea using blue-green argon, green argon, red krypton, or near-infrared diode is effective and economical method, but that the benefits are limited for vessels next to or below the fovea.
  
  Section::::Medical uses.:Retinopathy caused by sickle cell disease.
   Steroid and antibiotic eye drops are used to treat eye infections. They also have prophylactic properties and are used to prevent infections after eye surgeries. They should be used for the entire time prescribed without interruptions. The infection may relapse if the use of the medication is stopped.
  
  Section::::Types and uses.:Drug administration.:Glaucoma.
   There are multiple methods of washing red cells. These can include automated or manual methods. They can use centrifugation or centrifugation-free methods. The red cells can be re-suspended in saline or other types of special preservative solutions for red cells e.g. SAG-M.
  
  Section::::Medical Uses.
  
  Section::::Medical Uses.:Prevention of recurrence of severe allergic reactions.
   As with conventional manufactured drugs, the main challenge in developing successful offshoots of the RNAi-based drugs is the precise delivery of the RNAi triggers to where they are needed in the body. The reason that the ocular macular degeneration antidote was successful sooner than the antidote with other diseases is that the eyeball is almost a closed system, and the serum can be injected with a needle exactly where it needs to be. The future successful drugs will be the ones who are able to land where needed, probably with the help of nanobots. Below is a rendition of a table that shows the existing means of delivery of the RNAi triggers.
   In 2011, the first gene therapy treatment for choroideremia was administered. The surgery was performed by Robert MacLaren, Professor of Ophthalmology at the University of Oxford and leader of the Clinical Ophthalmology Research Group at the Nuffield Laboratory of Ophthalmology (NLO). In the study, 2 doses of the AAV.REP1 vector were injected subretinally in 12 patients with choroideremia. There study had 2 objectives:
  
  BULLET::::- to assess the safety and tolerability of the AAV.REP1 vector
  
  BULLET::::- to observe the therapeutic benefit, or slowing of the retinal degeneration, of the gene therapy during the study and at a 24-month post-treatment time point
   Another year later, the US-American ophthalmologist William Bates, perhaps motivated like Oliver, instilled adrenal extracts into the eye, found that ″the conjunctiva of the globe and lids whitened in a few minutes″, correctly explained the effect by vasoconstriction, and administered the extracts in various eye diseases. Later catecholamine literature has not done him justice. Even an ophthalmological review article of 1905 mentions him only in passing.
  
  Section::::Chemistry.
   Red-eye removal is built into many popular consumer graphics editing software packages, or is supported through red-eye reduction plug-ins; examples include Adobe Photoshop, Apple iPhoto, Corel Photo-Paint, GIMP, Google Picasa, Paint.NET and Microsoft Windows Photo Gallery. Some can automatically find eyes in the image and perform color correction, and can apply it to many photos at once. Others may require the operator to manually select the regions of the pupils to which correction is to be applied. When performed manually, correction may consist of simply converting the red area of pupils to grayscale (desaturating), leaving surface reflections and highlights intact.
   Retinaldehyde is a retinol (vitamin A) derivative responsible for vision. It binds rhodopsin, a well-characterized GPCR that binds all-cis retinal in its inactive state. Upon photoisomerization by a photon the cis-retinal is converted to trans-retinal causing activation of rhodopsin which ultimately leads to depolarization of the neuron thereby enabling visual perception.
  
  Section::::Activators of nuclear receptors.
  
  See the main article on nuclear receptors
  
  Section::::Activators of nuclear receptors.:Steroid Hormones.
   Dipivefrine penetrates the cornea and is then hydrolysed to epinephrine by esterase enzymes. It increases outflow of the aqueous humour and also reduces its formation (mediated by its action on α and α receptors), thus reducing pressure inside the eye. It also increases the conductivity of trabecular filtering cells (a β receptor mediated action). It is preferred to epinephrine because it is longer acting, more consistent in its action and better tolerated.
   A reduction in visual acuity in a 'red eye' is indicative of serious ocular disease, such as keratitis, iridocyclitis, and glaucoma, and never occurs in simple conjunctivitis without accompanying corneal involvement.
  
  Section::::Diagnosis.:Ciliary flush.
  
  Ciliary flush is usually present in eyes with corneal inflammation, iridocyclitis or acute glaucoma, though not simple conjunctivitis.
  
  A ciliary flush is a ring of red or violet spreading out from around the cornea of the eye.
  
  Section::::Diagnosis.:Corneal abnormalities.
   Diabetic cataract formation follows an increase in sugars in the lens. The excess sugar within the lens is reduced by aldose reductase to its alcohol, but the lens capsule is relatively impermeable to sugar alcohols. Because of the excess sugar alcohol (polyol), the lens imbibes water, causing osmotic imbalance. Eventually, increased sodium and decreased potassium levels and decreased glutathione levels lead to cataract formation. Topical administration of aldose reductase inhibitors have been shown to prevent the cataract in rats.
  
  Section::::Asthma and COPD.
   Section::::Regulation.:European Union.:Economic impact.
  
  In January 2013, the Humboldt Forum for Food and Agriculture e. V. (HFFA), a non-profit think tank, published a report on the value of neonicotinoids in the EU. At their website HFFA lists as their partners/supporters: BASF SE, the world's largest chemical company; Bayer CropScience, makers of products for crop protection and nonagricultural pest control; E.ON, an electric utility service provider; KWS Seed, a seed producer; and the food company Nestlé.
   Syringe designed saline drops (e.g. Wallace Cameron Ultra Saline Minipod) are distributed in modern needle-exchange programmes as they can be used efficiently either by injection or ophthalmic (if the drug is potent in small doses) route of administer which is compared to intravenous use; By demonstration, the elimination of latanoprost acid from plasma is rapid (half-life 17 minutes) after either ophthalmic or intravenous administration.
  
  Section::::Side effects.
   Steroid and antibiotic eye drops may cause stinging for one or two minutes when first used and if stinging continues, medical advice should be sought. Also, one should tell their doctor if vision changes occur or if they experience persistent sore throat, fever, easy bleeding or bruising when using drops with chloramphenicol. Also, one should be aware of symptoms of an allergic reaction, such as: rash, itching, swelling, dizziness, and trouble breathing. 
   In particular, IFITMs prevent HIV infection by preventing the virus from entering the host cell. It does this by S-palmitoylation, a process where fatty acids are added to an amino acid named cysteine. The process is crucial to the protein's antiviral properties and is of huge interest in research. Through studying Dispanin, it is hoped that its antiviral properties can be exploited, and then distributed in the form of medicines and vaccines.
   Eyes drops sometimes do not have medications in them and are only lubricating and tear-replacing solutions.
  
  Section::::Types and uses.:Drug administration.
  
  Section::::Types and uses.:Drug administration.:Dry eyes.
  
  There is a wide variety of artificial tear eye drops that provide different surface healing strategies. One can find bicarbonate ions, hypotonicity, viscosity, and non-preserved types. They all act differently and therefore, one may have to try different artificial tears to find the one that works the best.
  
  Section::::Types and uses.:Drug administration.:Steroid and antibiotic eye drops.
   The lack of a unified name for this technology makes reviewing the literature on the subject very difficult. Optical injection has been described using over a dozen different names or phrases (see bulleted lists below). Some trends in the literature are clear. The first term of the technique is invariably a derivation of word laser, optical, or photo, and the second term is usually in reference to injection, transfection, poration, perforation or puncture. Like many cellular perturbations, when a single cell or group of cells is treated with a laser, three things can happen: the cell dies (overdose), the cell membrane is permeabilised, substances enter, and the cell recovers (therapeutic dose), or nothing happens (underdose). There have been suggestions in the literature to reserve the term optoinjection for when a therapeutic dose is delivered upon a single cell, and the term optoporation for when a laser generated shockwave treats a cluster of many (10s to 100s) cells. The first definition of optoinjection is uncontroversial. The definition of optoporation, however, has failed to be adopted, with a similar number of references using the term to denote the dosing of single cells as those using the term to denote the simultaneous dosing of clusters of many cells 
   The tapetum lucidum, in animals that have it, can produce eyeshine, for example as seen in cat eyes at night. Red-eye effect, a reflection of red blood vessels, appears in the eyes of humans and other animals that have no tapetum lucidum, hence no eyeshine, and rarely in animals that have a tapetum lucidum. The red-eye effect is a photographic effect, not seen in nature.
  
  Some ophthalmologists specialise in this segment.
  
  Section::::Extraocular anatomy.
   Atropine eye drops have been shown to be effective in slowing the progression of myopia in children in several studies, but it is not available for this use, and side effects would limit its use.
  
  Section::::Medical uses.:Heart.
  
  Injections of atropine are used in the treatment of bradycardia (a heart rate  60 beats per minute).
  