Thursday, September 22, 2016

the contact lens case

As eye care professionals, we talk a lot about the proper care of contact lenses, but we probably don't spend enough time talking about the proper care of the contact lens CASE. Sure, it doesn't actually go ON your eyeball, but it does matter! The contact lens case can act as a reservoir for microorganisms and can be the source of eye infections, with the contact lens serving as the vector.  Some microbes can attach to the case and secrete substances that create an extracellular matrix-type protective encasement called a biofilm. This allows adherence to biological tissue, plastics, medical devices, etc. The ideal environment for biofilms to attach and grow is a moist surface, which makes contact lens cases prime real estate (1). 

So how should you be taking care of your contact lens case?

1. Change the case AT LEAST every 3 months.  Look at the photos below. Crystal violet stains protein and DNA, the primary components of cellular debris.  You can see that the intensity of the staining correlates with the age of the lens case (2). The longer you use the case, the more bacteria and debris collects, which increases your risk of infection.

image: RCCL

2. Clean the case daily by rubbing and rinsing with fresh contact lens solution (not water). A study found that 52% of those questioned cleaned their cases with tap water (3).  Why is that bad?  Because tap water contains microorganisms that can lead to rare but serious eye infections, like Acanthamoeba keratitis. In another study, cleaning cases with tap water was found to be associated with a higher rate of contamination with gram negative bacteria (4). Multipurpose solutions are designed to interfere with the cell membrane of microorganisms and kill them. Hydrogen peroxide-based solutions use a different method to disrupt the microbial membrane, as well as the DNA and other cellular components (5).  

3. Wipe the contact lens case with a clean tissue, and place the case upside down to air dry in a clean area (ie: not inches from the toilet). Simply rinsing with contact lens solution is not enough to destroy biofilms; mechanical disruption is needed (37).  More bacterial contamination was found to occur in humid environments, most notably when the case was left to air dry face up (8).  So the research tells us that the most effective way to clean your contact lens case is to rub and rinse the contact lens case with fresh contact lens solution daily, wipe the case with a clean tissue, and leave it face down on a clean surface to air dry (910).  

The proper way to store your case: upside down on a clean tissue.

4. Be sure to keep the contact lenses themselves clean!  More on that in a previous post.

Even better yet? Get rid of the case all together and opt for daily disposable contact lenses. You put them in in the morning, remove and discard them in the evening, and start with a fresh pair the next day. Talk to your optometrist to see if those are an option for you.

CliffsNotes: Rub and rinse the contact lens case with fresh contact lens solution (not water) daily, dry with a clean tissue, and leave upside down on a clean tissue to air dry. RUB, RINSE, TISSUE-DRY, AIR-DRY. Replace the case at least every 3 months. 

Additional Resources:

Thursday, September 1, 2016

the history of eyeglasses

A few weeks ago, I saw a 16 year old patient that was interested in optometry as a potential career path. He asked a few questions about the field and schooling, then he asked me a question that stumped me: "When were glasses invented?"

::Crickets:: I am admittedly not a history buff, but this was one I probably should have known. So this blog post is for you, inquisitive teenager S.

When were eyeglasses invented?
Short answer: In the 1200s.

Long answer: The invention of the eyeglass is thought to have occurred in Italy between 1268 and 1289. The use of glass as a means of enhancing vision was mentioned in a few manuscripts around this time. One such mention was in a book by Robert Grosseteste printed in 1235. It referenced using a glass to “read the smallest letters at incredible distances.” In 1268, the English philosopher Roger Bacon wrote: "If anyone examine letters or other minute objects through the medium of crystal or glass or other transparent substance, if it be shaped like the lesser segment of a sphere, with the convex side toward the eye, he will see the letters far better and they will seem larger to him. For this reason such an instrument is useful to all persons and to those with weak eyes for they can see any letter, however small, if magnified enough."

In 1289, Sandra di Popozo wrote in a manuscript: "I am so debilitated by age that without the glasses known as spectacles, I would no longer be able to read or write. These have recently been invented for the benefit of poor old people whose sight has become weak." In 1306, a monk of Pisa delivered a sermon in which he stated: "It is not yet twenty years since the art of making spectacles, one of the most useful arts on earth, was discovered. I, myself, have seen and conversed with the man who made them first." Thus, we conclude that eyeglasses arrived on the scene in the mid-1200s.

The first artistic rendering of spectacles was found in a fresco of Cardinal Hugo of Provence painted by Tommaso da Modena around 1352.
Tomasso da Modena's painting
image: History of Information

In their early days, glasses were worn primarily by monks and scholars. They were essentially two pieces of glass or crystal riveted together, with the lenses bound in leather, metal, or bone. They were either held in front of the eye or balanced on the nose. It wasn't until the invention of the printing press around 1440-1450 that eyeglasses became a common item.

Early spectacles, framed in leather
image:AAO Museum of Vision

The idea of attaching ribbons of silk to the frames and looping them over the ears emerged in the 17th century by Spanish spectacle makers. This idea made it over to China by way of Spanish and Italian missionaries. The Chinese modified this, adding little ceramic or metal weights to the string to hold it in place behind the ear, instead of using a loop. Edward Scarlett, an optician in London, is credited with creating the rigid sidepiece that rested over the ears in 1730. Thus, the spectacle temple was born.
Edward Scarlett's trade card, the first advertisement of rigid temples 
image: The College of Optometrist Museyeum
Martin's Margins 
image: AAO Museum of Vision
Binocles-ciseaux, or scissor-glasses, reached the height of their popularity in the latter half of the 18th century. George Washington and Napoleon Boneparte are said to have used these.
image: AAO Museum of Vision
Another form of spectacles that came about in the 18th century was the lorgnette, a pair of lenses that were held in front of the eyes by a side handle. These may have developed from the scissor-glasses. Created by George Adams, lorgnettes often had ornate and embellished handles, as they were worn mostly by fashionable women.
The lorgnette (everyone should have a fan attached to their specs) 
image: AAO Museum of Vision
The monocle, interestingly called an "eye ring," become popular in the mid to late 1800s, though they are thought to have developed in Germany earlier. The monocle was most often worn by upper class men. And, of course, Mr. Peanut.
The monocle- who wore it best?
The 1800s saw the oval frame shape come to prominence, as well as the emergence of bifocals. Benjamin Franklin is widely credited for the invention of the bifocal in the 1780s, though the jury is still out on that one.  B.M. Hanna (Hannas unite!) received patents for the cemented and perfection bifocals in the late 1800s.

Pince-nez is a style of glasses that came about in the 1840s. French for "pinch nose," these specs literally pinched the nose and usually had a chain that attached to a lapel or dress. President Teddy Roosevelt was often pictured wearing these. (Aside: check out this interesting story about how President Roosevelt's eyeglass case helped him dodge a bullet.)

Speak softly and carry a big stick. And wear your pince-nez.  
Another interesting tidbit for my eye nerds out there: J. J. Bausch emigrated to the US from Germany in 1850. He had apprenticed with an optician and came to America in search of better opportunity. He set up shop in NY as an optician, and struggled for many years. He sought a $60 loan from his friend, Henry Lomb, and Lomb became an apprentice under Bausch. Bausch created frames out of vulcanized rubber, which were stronger and less expensive than the current metal, animal horn, or wood frames out there. Demand for the product increased, and J.J. Bausch and Henry Lomb eventually went on to build the Bausch and Lomb Optical Company. For those of you that may not know, Bausch and Lomb still exists today, making it one of the oldest continuously operated companies in the US (more info here and here).

The 1900s saw eyeglasses become stylish in addition to functional. A wider variety of eyeglasses were available, and the stigma around wearing eyeglasses was beginning to fade away. Movie stars became style icons, and their glasses were part of their image. Sunglasses also became popular in the 30s. Progressive addition lenses (PALs) were invented in the 50s.
Comedian Harold Lloyd, "the man who popularized eyeglasses in America," wearing his iconic horn-rimmed glasses.
image: Wikipedia

And here we are, in the present, where eyeglasses are considered part of a person's wardrobe, an accessory even. Some old trends are coming back, and some new ones are being created. There are now more eyeglass styles and colors than you can dream of, and they are such a fun (and useful) form of self-expression.

CliffsNotes: Eyeglasses were invented in Italy in the 1200s. They've come a long way since then. :)