What Are Scleral Contact Lenses?

In the beginning…of contact lenses…there were scleral lenses…only.

In the year 1887 a great gift was given to the world of sufferers of distorted vision resulting from corneal tissue that was irregular in shape from disease or trauma.
scleral lenses

The contact lens was invented nearly simultaneously by physicians working separately in Germany and in France. Working from drawings of Leonardo da Vinci (1508) and ideas of the British astronomer Sir John Herschel (1828), August Müller and separately Adolph Fick and Eugene Kalt blew glass shells to fit the outer eye and to some extent remedy their visual difficulties. These lenses rested on the conjunctiva of the eye above the sclera or white of the eye and were thus the first scleral contact lenses — the first contact lenses of any sort.

What are Scleral Contact Lenses?

The design and manufacture of scleral lenses has been a story of technological development significant for improvement in comfort, material, and affinity for the ocular surface.

For many years the lenses were partially molded and partially ground from the material of which hard contact lenses are made: PMMA (poly-methyl methacrylate) known as Plexiglas or Perspex. To form these lenses, like tooth implants, a plaster cast is made from a negative mold prepared from dental impression putty. The plastic would be heated and given the shape of the fitting surface of the lens from the plaster cast and then the power and edge curves would be ground onto the outside surface of the lens. Later came preformed trial sets not unfamiliar to those which we use today.

The current generation of scleral lens fitting began sometime in the last fifteen years with the mating of advanced corneal topography measurements, computer driven lathes and the observations of some very clever contact lens scientists. Proprietary designs of scleral lenses offering a variety of diameters, fitting philosophies, and multiple parameters are filling the gaps contact lens specialists have been wrestling with using smaller corneal contact lens designs for decades with less than optimal results. Most recently a firm has begun manufacturing lenses with a 3-D printer from an image generated from the eye. One eye…one lens, the lens is meant to fit like a fingerprint.

When discussing contact lens treatment, experts are experts because they agree that, any sort, size, or design of lens will have both positive and negative effects on the eyes and the tissues surrounding them. While it is true that many of the fitting and comfort issues confronted with corneal lenses of any size and design can be managed well with scleral designs, the scleral lens can also be difficult for some patients; for some eyes; for some conditions.

From the outset the larger size of the today’s scleral lens provides comfort on par with soft contact lenses for exactly the same reason: their size. Also, like soft contact lenses the scleral will not move around on the surface of the eye allowing the wearer a much more relaxed contact lens experience — there is no necessity to balance small corneal lenses between tense eyelids – vision can be enjoyed in any direction of gaze. The lenses will not fall off the eye and the increased size is a clear plus in finding a dropped contact lens.

On the other hand the quality of vision gained with scleral lenses specifically in cases of distorted corneae is far more comparable to that achievable with corneal GP lenses than with soft contact lenses in most cases.

Over the years my keratoconus patients have benefited from a series of contact lens breakthroughs that have variously improved the quality of their vision, their comfort with contact lenses, or in some other way the health of their eyes. Some years ago I “re-invented” the piggy-back system of contact lens wear which I summarized in 2008 in an article published in the Contact Lens Spectrum. Piggy-backers would place their vision restoring firm contact lens on top of a disposable daily wear lens of minimal focusing power. The soft lens would reduce the sensation of the firm lens while in many cases preventing the contact lens from abrading the cornea. More recently I have been successfully moving patients to scleral lenses because there is certainly less bother (only one lens per eye) and far less worry over corneal abrasions as the lens rests on the conjunctiva over the sclera and maintains a fluid cushion over the cornea itself.

Scleral lenses are finding their place in the world of contact lens fitting primarily to remedy vision problems from very irregular or otherwise damaged corneae both those caused by developing disease and trauma through injury or surgery. More and more, these lenses are requested by patients with normal eyes who want to enjoy the benefits provided by these lenses while participating in sports or other activities.

Scleral lenses are renowned for their greater comfort. In many cases a correctly fitted lens can be worn for many waking hours. Many patients have found that they benefit from exchanging the fluid from the reservoir from time to time throughout the day. The fluid that fills the lens-cornea space is sterile, non-preserved normal saline or in some cases saline with a non-preserved tear substitute added when needed for improved comfort.

A proper care regimen for scleral lenses is not different from that for any other contact lens manufactured from a firm oxygen permeable material. The lenses require cleaning upon removal, soaking in a recommended solution appropriate to the material of the lens and a periodic treatment to remove protein deposits. Of course, the exact care specifications will vary from patient to patient according to the evaluation of their contact lens specialist.

Just like any lens modality, the fitting requires expertise. Many who fit and dispense contact lenses rely on boxed soft lenses for their patients. When corneae become distorted those lenses will hardly fill the need. Greater expertise is required to fit rigid corneal lenses needed for these more problematic surfaces. The decision of the corneal lens expert to move on to the world of larger lenses is not of the same magnitude as that from boxes to corneal GP lenses. The investment is more a matter of time spent in discussion with the manufacturer’s fitting consultants, some reading, a webinar or two and keeping up to date with the lens designs that are available.

I was not among the first to use the current generation of scleral lenses, but when the opportunity knocked some years ago, I realized the importance of this form of contact lens and I believe I have positively influenced the quality of life of many of my patients.

5/28/15

Bezalel Schendowich - scleral lensesBezalel Schendowich, OD
Medical Advisory Board of the National Keratoconus Foundation
Fellow of the International Association of Contact Lens Educators
Clinical Supervisor & Specialty Contact Lens Fitter, Sha’are Zedek Medical Center, Jerusalem, Israel

End of the Day Syndrome

4/2/14

“Dr. S., my eyes are red and burning at the end of my work day.”

“Patient, what sort of work do you do?  Tell me something about your work conditions.”

“I am a computer graphics artist.  I sit and stare at my twenty-seven inch HD screen for hours on end gently adjusting the composition of each pixel.  My studio is air-conditioned but not humidified, so after some hours of work, I feel dry as a bone.”

“One more question…can you cry tears?  Say, when you peel and slice an onion?”

Rule of 20 - blinking

The need to blink

Blinking is a complex function of the eyelids that when completed results in a clean, refreshed, re-wetted corneal surface.  The tears that are washed across the outside of the eye with each blink bring oxygen and other nutrients to the outer cell layer aiding in the rebuilding and revitalizing of the surface tissue.

Blinking is characterized by a full sweep of the upper lid over the eye to meet the lower lid.  The completion of this motion is performed gently without squeezing.  And, to be effective full eye closure needs to be repeated fairly often.  Blink rates vary according to investigators but most sources report an average of between six and ten full blinks per minute under normal viewing circumstances.

The anti-blink problem of our generation

In olden times – say the years between 1750-1950 – the most aggravating problem to the ocular surface was a good book or intense study.  The reader would concern himself with the text at hand and slowly his eyes would dry until a “rest break” was necessary.

Environmental or vocational changes to our lifestyle over the generations have promoted reduced blink rates.  Most recently in this negatively developmental progression is the effect of the television screen, the CRT, the LED screen, the handheld and pocket computer on the blink rate.  It appears that as attention level increases, blinking suffers.  First the eyes close less, then incompletely, and finally rarely only when surface dryness drives the individual to desperate measures.  He must blink or (so he feels) his eyes will pop out of their sockets.

Adding insult to injury increasingly over the decades is air conditioning – both heating and cooling – when not humidified.  Staring at console screens in dry environs speeds the desiccation of the cornea and results in discomfort.

The surface of the eye is a biological system.  Living systems require some degree of moisture.  If the cells of the eye – or any biological surface — are permitted to dry out, they will die.  Dead corneal cells fall off the cornea and float in the tears on the surface of the eye until washed away with a blink.  Until the surface is cleaned the dead cells are considered by the eye to be foreign bodies with the consequent irritation and induced reflex to blink.

When cells die and fall off, the underlying nerve endings send pain signals to the nervous system.  The sensation can be felt as pain, burning, or mere irritation or itching depending upon the severity of cell loss.

How to handle environmentally induced dry eye

After the ocular surface is dry most treatments will seem to make matters worse:  to cause burning and stinging, perhaps, even more than the dry eye itself.  Any tear substitute, any amount of blinking will be irritating at first. But, that is really all that can be done at this stage:  wetting and blinking.

Prevention

As in many conditions, the best treatment, in fact a cure, for recurrent environmentally induced dry eye is prevention.  For the eye that has a naturally flowing tear supply, the act of blinking is the surest prevention to stinging and burning after a day’s work at the computer.  Additionally, many sources recommend using the ‘rule of 20’:  after each twenty minutes of work, look up from the text or away from the screen; blink and refocus on the page twenty times.  This repetitive exercise simultaneously re-wets the eye and relaxes the focusing mechanism of the eye.

The result is relaxed and comfortable eyes that can continue to provide important and high quality information for longer hours of work.

Bezalel-SchendowichBezalel Schendowich, OD
Chairperson and Education Coordinator, JOS
Fellow, IACLE
Member, Medical Advisory Board NKCF
Sha’are Zedek Medical Center, Jerusalem, ISRAEL

Help for Computer Users

Working long hours in front of the computer requires a fairly unchanging body, head and eye position which can cause discomfort.  Correct working position, periodic stretch breaks, frequent eye blinking, artificial tears for lubrication are all very important.  However, it’s not always easy to remember this when you are engrossed in work. Here are a few fun, free and easy-to-install “break reminders” to help:

WorkSafe Sam - break reminder
WorkSafe Sam

WorkSafe Sam is a desktop tool that provides stretching tips to help reduce eye and muscle strain for office workers (clicking on this link will open a file on your computer because this is a zip file).

Workrave is break reminder program that alerts you to take “micro-pauses” and stretch breaks.

Take Your Break is another break reminder designed to prevent or minimize repetitive strain injury, computer eye strain and other computer related health problems.  It has a friendly interface and a tray icon status indicator.  It runs quietly in the background, monitoring your activity and reminding you to take regular breaks.

And remember to blink.  Blinking cleans the ocular surface of debris and flushes fresh tears over the ocular surface. Each blink brings nutrients to the eye surface structures keeping them healthy. The flow of tears is responsible for wetting the lower third of the cornea. This is very important in KC, since this area is generally below the bulge of the cone and in many cases irritated by wobbly RGP lenses.  Maybe your job requires hours of work at a computer. Maybe you like to spend your free time surfing the internet. Whatever the reason, your body is probably feeling the effects of spending too much time staring at a computer monitor, which could result in Computer Vision Syndrome (CVS).  The most common symptoms are: eye strain, dry or irritated eyes,redness in eyes,difficulty in refocusing eye,neck pain,double vision,blurred vision, fatigue, and headaches.

Please join us on Thursday when Dr. Bezalel Schendowich will be providing a detailed insight into the importance of blinking, going beyond computer usage.

CathyW headshotCathy Warren, RN
Executive Director
National Keratoconus Foundation