science

Intravitreal administration

Intravitreal administration is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Intravitreal administration rather than just read about it. In short: Intravitreal administration is a route of administration of a drug, or other substance, in which the substance is delivered into the vitreous humor of the eye. "Intravitreal" literally means "inside an eye". Intravitreal injection is the method of administration of drugs into the eye by injection with a fine needle.

Key takeaways

Intravitreal administration belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Intravitreal administration to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Intravitreal administration from memory before moving on to harder problems.

Reference excerpt

Intravitreal administration is a route of administration of a drug, or other substance, in which the substance is delivered into the vitreous humor of the eye. "Intravitreal" literally means "inside an eye". Intravitreal injection is the method of administration of drugs into the eye by injection with a fine needle. The medication will be directly applied into the vitreous humor. It is used to treat various eye diseases, such as age-related macular degeneration (AMD), diabetic retinopathy, and infections inside the eye such as endophthalmitis. As compared to topical administration, this method is beneficial for a more localized delivery of medications to the targeted site, as the needle can directly pass through the anatomical eye barrier (e.g. cornea, conjunctiva and lens) and dynamic barrier (e.g. tears and aqueous humor). It could also minimize adverse drug effects on other body tissues via the systemic circulation, which could be a possible risk for intravenous injection of medications. Although there are risks of infections or other complications, with suitable precautions throughout the injection process, chances for these complications could be lowered. Intravitreal injections were first introduced in 1911 when Ohm gave an injection of air into the vitreous humor to repair a detached retina. In the mid-1940s, intravitreal injections became a standard way to administer drugs to treat endophthalmitis and cytomegalovirus retinitis.

Epidemiology Intravitreal injections were proposed over a century ago, however the number performed remained relatively low until the mid 2000s. Until 2001, intravitreal injections were mainly used to treat end-ophthalmitis. The number of intravitreal injections stayed fairly constant, around 4,500 injections per year in the US. The number of injections tripled to 15,000 in 2002, when triamcinolone injections were first used to treat diabetic macular oedema. This use continued to drive an increase to 83,000 injections in 2004. In 2005, bevacizumab and ranibizumab intravitreal injections for the treatment of wet-AMD caused a rise in injections to 252,000. In 2008, over 1 million intravitreal injections were performed. This doubled to 2 million just 3 years later in 2011 when aflibercept (another anti-VEGF intravitreal injection) became available for the treatment of wet AMD. Intravitreal injections hit an all-time high in 2016, reaching over 5.9 million injections in the US.

History Intravitreal injection was first mentioned in a study in 1911, in which the injection of air was used to repair a detached retina. There were also investigations evaluating intravitreal antibiotics injection using sulfanilamide and penicillin to treat endophthalmitis in the 1940s, yet due to the inconsistency of results and safety concerns, this form of drug delivery was only for experimental use and not applied in patients. It was until 1998, that fomivirsen (Vitravene), the first intravitreal administered medication, was approved by the U.S. Food and Drug Administration (FDA). In 2004, when Aiello et al. published the first guidelines for intravitreal injection in the journal Retina, fomivirsen was still the only medication licensed by the FDA for intravitreal injection. At the end of the year, on December 17, the first intravitreal anti-VEGF drug pegaptanib (Macugen) was also licensed by FDA for treatment of wet age-related macular degeneration (wet AMD). Intravitreal injection has then become more common and a surge in the number of injections performed could be seen. Six extra medications, namely triamcinolone acetonide, ranibizumab (Lucentis), aflibercept (Eylea/Zaltrap), dexamethasone, ocriplasmin and fluocinolone acetonide were approved for this injection by the end of 2014. There are also increasing off-label use of bevacizumab (Avastin) for the management of various ophthalmologic diseases, like AMD, retinal vein occlusion and diabetic macular edema. On top of that, the number of intravitreal injections has escalated from less than 3000 per year in 1999, to an estimation of near 6 million in 2016.

Uses Intravitreal injection is used to inject a drug into the eye to reduce inflammation (anti-inflammatory), inhibit the growth and development of new blood vessels (angiostatic), or lower the permeability of blood vessels (anti-permeability), in turn curing various eye diseases. Disorders/diseases that can be treated with intravitreal injection include:

Age-related macular degeneration (AMD)/ Macular Degeneration: An eye disorder that slowly destroys sharp, central vision Uveitis: Swelling and inflammation within the eyeball Retinal vein occlusion: A blockage of the veins that carry blood away from the retina, the back part of your eye, and out of the eye Macular edema: Swelling or thickening of the macula (the central area of the retina that provides sharp, central vision) due to abnormal fluid accumulation Diabetic macular edema: Poorly controlled diabetes mellitus could lead to diabetic retinopathy, i.e., damages to the retina. The damage to the small blood vessels there causes leakage of fluid Pseudophakic cystoid macular edema Macular edema secondary to retinal vein occlusion Macular edema secondary to uveitis Infections, such as endophthalmitis and retinitis Noninfectious vitritis Sometimes, an intravitreal injection of antibiotics and steroids is given as part of routine cataract surgery. This avoids having to use drops after surgery.

Antimicrobials Antimicrobials are intravitreally injected to treat eye infections, such as endophthalmitis and retinitis. The medication used depends on the pathogen responsible for the disease.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Intravitreal administration

Start with the simplest possible case. Write down what Intravitreal administration claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Intravitreal administration before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Intravitreal administration ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Intravitreal administration

In research: Intravitreal administration appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Intravitreal administration in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Intravitreal administration is common in secondary-school and first-year university syllabi. It links to neighbouring topics Medical treatments, Ophthalmic drug administration, so understanding it makes those chapters shorter.
In everyday life: Look for Intravitreal administration outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Intravitreal administration in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Intravitreal administration means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Intravitreal administration out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Intravitreal administration in simple terms?

Why does Intravitreal administration matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Intravitreal administration?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Intravitreal administration.