science

ReNu

ReNu 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 ReNu rather than just read about it. In short: ReNu is a brand of soft contact lens care products produced by Bausch & Lomb. By far the most popular brand of lens solutions until 2006, ReNu has rebranded its formulations as renu sensitive (formerly ReNu Multi-Purpose) and renu fresh (formerly ReNu MultiPlus), the latter containing a patented ingredient called hydranate, known by chemists as hydroxyalkylphosphonate, that removes protein deposits and can eliminate…

Key takeaways

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

Reference excerpt

ReNu is a brand of soft contact lens care products produced by Bausch & Lomb. By far the most popular brand of lens solutions until 2006, ReNu has rebranded its formulations as renu sensitive (formerly ReNu Multi-Purpose) and renu fresh (formerly ReNu MultiPlus), the latter containing a patented ingredient called hydranate, known by chemists as hydroxyalkylphosphonate, that removes protein deposits and can eliminate the need for a separate enzymatic cleaner.

ReNu with MoistureLoc The brand made headlines in 2006 when a report from the United States Centers for Disease Control and Prevention suggested an increased incidence of fungal keratitis in people using Bausch & Lomb products. Bausch & Lomb subsequently suspended, then recalled shipments of one particular product, ReNu with MoistureLoc. Other ReNu formulations were unaffected, as they do not include the special ingredient in MoistureLoc, which was supposed to keep lenses moist but unfortunately also allowed microbes to survive the disinfection process.

Timeline In November 2005, Hong Kong health officials told Bausch & Lomb about a significant increase in hospital admissions due to contact lens related keratitis from June to September 2005. On March 3, 2006, New Jersey ophthalmologist Dr. David S. Chu contacted Bausch & Lomb to report that three of his patients had contracted a fungal infection called Fusarium keratitis; all three of these patients were contact lens wearers who used Bausch & Lomb's Renu with MoistureLoc. Subsequently, he also reported his findings to the Centers for Disease Control and Prevention on March 8, 2006. On April 10, 2006, the CDC announced that it was investigating 109 patients in the United States suspected to have Fusarium keratitis. They reported that they had complete data available for 30 patients in this group, the earliest onset of infection of which was June 15, 2005. On April 11, 2006, Bausch & Lomb stopped shipments of its ReNu with MoistureLoc contact lens solution from its Greenville, South Carolina, plant after the U.S. Centers for Disease Control and Prevention found what appeared to be a high correlation between use of the product and cases of suspected fungal keratitis. Similar claims had already been made against the product in Hong Kong and Singapore. The news about the U.S. suspension led to a 14.6% drop in the company's stock price—a drop of $8.41, to $49.03—the largest the company experienced in 5½ years. On April 13, 2006, Bausch & Lomb announced that it is withdrawing the ReNu with MoistureLoc product world-wide and is recommending that consumers stop using ReNu with MoistureLoc immediately. The FDA supports this decision. The FDA, as well as the American Optometric Association, also advise now that contact lenses be rubbed and rinsed even when a no-rub contact lens solution is used. According to a preliminary report released by the FDA on May 16, 2006, Bausch & Lomb failed to notify the FDA that Singapore's Ministry of Health reported 35 serious cases of Fusarium keratitis to Bausch & Lomb in February 2006. The U.S. suspension does not include ReNu products without MoistureLoc. Only supplies of ReNu with MoistureLoc manufactured in the company's US plant are affected. European supplies are considered to be safe. On March 7, 2007, Bausch & Lomb issued a voluntary recall on 1.5 million bottles of ReNu MultiPlus solution due to higher than normal amounts of iron in the batch.

References

External links Contact Lenses Contact Lens Safety US FDA Notification Of ReNu Withdrawal

Worked examples

Example 1 — a first encounter with ReNu

Start with the simplest possible case. Write down what ReNu 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 ReNu 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 ReNu 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 ReNu

In research: ReNu 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 ReNu 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: ReNu is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cleaning products, Contact lenses, so understanding it makes those chapters shorter.
In everyday life: Look for ReNu 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 ReNu in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what ReNu 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 ReNu out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is ReNu in simple terms?

Why does ReNu 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 ReNu?

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 ReNu.