Little Bottle, Big Relief

6/3/14

What you need to know about eye drops.

Have you been staring at a computer all day and your eyes are tired? Have allergies been making your eyes watery and itchy? Are your contact lenses irritating your eyes? If you have experienced any of these conditions, you have probably turned to eye drops for relief.

While eye drops are an easy and effective means of treating a number of eye issues, there are many different eye drops available, both over the counter (OTC) and by prescription. It is wise to know what your underlying condition is before trying to get relief.

If your eyes are red and you may want to try a decongestant eye drop, which will shrink the tiny blood vessels in the “whites” of your eyes (sclera), but they also cause dryness so may not be a good choice if you wear contact lenses.
For lens wearers you are better off with a re-wetting drop to lubricate the eye and lens making you more comfortable. Another problem with the decongestant eye drops is over use – which can cause irritation and an increased tolerance that could lead to more redness.

If you suffer from allergies and antihistamine eye drop would be the best choice for relief from itchy, watery, red and swollen eyes. They work by reducing histamine in the eye tissue.

Lubricating eye drops, also known as artificial tears, are for short-term relief caused by temporary situations such as eye strain form computer use, being tired or being outdoors in windy and/or sunny conditions. If the condition is chronic, a prescription eye drop will be the best choice.

It is important to remember that if any of the above symptoms worsen or continue for an extended period of time, it is time to see your eye doctor to determine the underlying cause of your issue and to rule out eye disease. Postponing a visit could also lead to an eye infection.

Prescription drops are used to treat a wide variety of eye diseases such as glaucoma, dry eye and the symptoms of ocular herpes. They are also used to help with healing from cataract surgery, corneal transplants, glaucoma surgery and even Lasik. it is extremely important to use them as often as your ophthalmologist recommends to improve healing and prevent infection.

Because of the ease of applying eye drops researchers are working toward using them to treat other eye diseases. Ocular herpes symptoms are sometimes treated with antiviral and steroid drops. But this only is targeted at the symptoms and not the underlying cause, the herpes simplex virus. Lbachir BenMohamed, PhD and Steven Wechsler, PhD at the University of California, Irvine, Gavin Herbert Eye Instittue have been working to determine what reactivate the herpes simplex virus and develop an eye drop that would either stop the reactivation of the virus or kill it.

Using eye drops to treat age-related macular degeneration (AMD) is also being explored. Researchers at the Institute of Ophthalmology at University College London are working with nanoparticles to deliver anti-VEGF drugs such as Lucentis and Avasitn to the back of the eye via drops. “The study shows that Avastin can be transported across the cells of the cornea into the back of the eye, where is stops blood vessels from leaking and forming new blood vessels, the basis for wet AMD.” While researchers in the Department of Ophthalmology, Tufts University School of Medicine in Boston “reported in their “proof of concept” study that topical application of a compound called PPADS inhibits damage to the tissues in the eye that impacts the individual’s ability to see color and fine detail, as well as reduces the growth of extraneous blood vessels in the back of the eye related to AMD.” It would work in both dry and wet AMD reduce the need for direct injections.

Eye drops, when properly applied, can provide temporary relief from symptoms of eye discomfort. But if the symptoms worsen or continue for an extended period of time, consult your eye doctor. To make sure you apply the eye drops correctly check out the article in our February 2013 newsletter for 12 easy steps to get the drops into your eyes and avoid infection.

One final note – keep your eye drops out of reach of children. Eye drops come in small bottles that are the perfect size for small hands and don’t have the same security tops found on other medications. The FDA has warned that ingredients found in some eye drops that relieve redness have caused abnormal heart rate, decreased breathing, sleepiness, vomiting and even comas in children five and younger that have ingested them. If you child has swallowed eye drops, call the Poison Help Line 800-222-1222.

Susan DeRemer
Vice President of Development
Discovery Eye Foundation

New Technology for Evaluating Contact Lenses

5/1/14

Successful management with contact lenses can sometimes be a frustrating process for those with keratoconus. The fitting and evaluation process involves numerous visits to the optometrist, out of pocket expenses as well as medical insurance co-pays. Luckily, the contact lens industry has responded to the need to have better contact lens materials for patients with keratoconus. It used to be that the only contact lenses available to manage keratoconus were gas-permeable (GP) lenses. Now, more and more patients are being fit with newer generation hybrid lenses (GP lens core with a skirt of soft lens material to aid in fit and comfort) and scleral lenses (large diameter GP lenses that do not rest on the cornea, only the outlying sclera). These newer designs are intended to vault over the central cornea and do not rest on the cornea at all. They have resulted in much more comfortable and wearable strategies for full-time use. As a result of the newer lens designs, the game has changed when it comes to the science of fitting and evaluating the lenses.

For years, optometrists have used corneal topography to guide their decision making on fitting keratoconic eyes. A corneal topographer is an instrument that maps the shape of the cornea, and gives information much like that of a topographical map for hiking. Corneal topography is still an absolutely mandatory part of evaluating the shape of the cone, the simulated corneal curvature, and monitoring for progression of the disease, and is not a standard part of a typical eye examination. However, doctors have a new tool at their disposal for fitting contact lenses on patients with keratoconus.

Optical Coherence Tomography (OCT) was once reserved for use in the back of the eye, or retina. OCT uses visible light passed through the clear structures of the eye to generate a cross-sectional image of the layers of the retina, much like an image generated by an MRI. Advances in OCT technology has improved the resolution to image the eye on the micrometer scale (one-thousandth of a millimeter). OCT technology is now commercially available not only for the retina, but the structures of the front part of the eye. The obvious application is to aid the doctor in the fitting and evaluating complex contact lenses that vault the cornea.

Figure 1. OCT image of a scleral lens fit on a keratoconic patient. The cornea is the opaque white band located at the bottom of this picture, the tear film reservoir is the middle clear band and the contact lens is the top band. Using an electronic caliper tool, the precise amount of vault can be measured, leaving no doubt as to the precision of the fit.

OCT allows the optometrist to view a cross-sectional image of the contact lens on the eye in real time and to monitor the health of the cornea in the presence of the contact lens. This view is valuable for judging the vault of new designs of contact lenses over the cornea and judging where the lenses land on the eye. It is the most specific way to determine if the fit is acceptable and to troubleshoot if lenses are not fitting appropriately.

Figure 2. OCT image of the periphery of a scleral lens on a patient with pellucid marginal degeneration. The lens contacts the cornea over an area of 0.87mm long. These types of measurements help guide decision making in modifying the lens fit and were impossible before the advent of this technology.

Figure 3. Hybrid lens on a highly irregular eye after corneal transplant. The point of contact of the soft skirt with the cornea is visible to the right of the image.

Optometrists now have a much more powerful tool for evaluating and managing even the most challenging contact lens fits. It remains to be seen whether this technology has the ability to reduce the number of visits required for successful fit. But, the precision afforded by this technology does have the ability to improve patient outcomes.

Jeffrey Sonsino, OD, FAAO
The Contact Lens Center at Optique Diplomate
Cornea, Contact Lens, and Refractive Therapies

The Evolving Contact Lens

4/22/14

Contact lenses give a person the ability to see without glasses. If you have keratoconus, they are essential for seeing as regular glasses don’t work with an irregularly shaped cornea. But lately these relatively simple lenses have created a whole new world where they can dispense eye medication, measure blood glucose levels and even help the blind see.

Monitoring Blood Sugar
You have heard about Google Glasses, but Google is looking beyond the smartphones of eye wear to monitoring health. They are currently working on a lens with tiny wireless chips and glucose sensors that are sandwiched between two lenses. They would monitor glucose levels once a second and use tiny LED lights, also inside the lenses, to flash when the levels are too high or low. And how big are these electronics? They are no larger than a speck of glitter, with a wireless antenna that is thinner than a human hair. While they are still in development – Google has run clinical research studies and is in discussions with the FDA – it could make blood sugar monitor far less invasive than pricking your finger several times a day.

Drug Delivery for Glaucoma
Getting glaucoma patients to regularly use their eye drops to regulate the pressure in their eyes has always been a problem. They forget, don’t want to be bothered, or have a hard time getting the drops into their eyes. This could change with two research projects exploring the use of contact lenses to deliver medication over a prolonged period of time.

Researchers at Massachusetts Eye and Ear/Harvard Medical School Department of Ophthalmology, Boston Children’s Hospital, and the Massachusetts Institute of Technology who are working on a lens designed with a clear central area and a drug-polymer film made with the glaucoma drug latanoprost, around the edge to control the drug release. These lenses can be made with no refractive power or the ability to correct the refractive error in nearsighted or farsighted eyes.

Another team from University of California, Los Angeles have combined glaucoma medication timolol maleate with nanodiamonds and embedded them into contact lenses. When the drugs interact with the patient’s tears, the drugs are released into the eye. While the nanodiamonds strengthen the lens, there is no difference in water content so they would be comfortable to wear and allow oxygen levels to reach the eye.

Seeing in the Dark
Researchers out of the University of Michigan have developed an infrared sensor that could eventually be used in the production of night vision contact lenses. Thanks to graphene, a tightly-packed layer of carbon atoms, scientists were able to create a super-thin sensor that can be stacked on a contact lens or integrated with a cell phone.

Stem Cells for Cornea Damage
Researchers in Australia are working on a way to treat corneal damage with stem cell infused contact lenses. Stem cells were taken from the subject’s good eye and then plated them onto contact lenses (if there is a defect in both eyes, stem cells are taken from a different part of the eye). After wearing for about two weeks the subjects reported a significant increase in sight.

Helping the Blind See
And what good are contact lenses if you are blind? At Bar Ilan University in Israel researchers are creating special lenses that translate images into sensations felt on the eye. It works by taking an image with a smartphone or camera, it is then processed and sent to the contact lens. The custom-made lens is fitted with a series of electrodes that use small electric impulses to relay shapes onto the cornea, similar to braille. After some practice, test subjects were able to identify specific objects.

In expanding the uses of contact lenses, these projects seem to be just the beginning, all reported in the first four months of this year. Researchers and developers are working together to find more and better ways help with vision and medical issues, using contact lenses.

Susan DeRemer, CFRE
Vice President of Development
Discovery Eye Foundation

Wavefront Sensing Applied to Custom Contact Lens Research in Keratoconus

4/10/14

During a trip to the optometrist or ophthalmologist, a patient will encounter the process of subjective refraction. This technique involves the clinician asking the patient to make a series of judgments (which is better, one or two?) about the clarity of their vision when looking through a series of lenses. The choices that the patient makes guide the clinician in identifying an optical prescription which is typically made up of sphere, and potentially, cylinder lenses.

Why is it that glasses don’t always work for patients with keratoconus?

In many instances, individuals with keratoconus do not achieve excellent visual performance with spectacles or traditional soft contact lenses. One cause for the failure of these corrections is that the changes in corneal shape that accompany keratoconus induce refractive errors which traditional spectacles simply cannot correct. So, even when sphere and cylinder in the keratoconic eye are well-corrected, these “other refractive errors” or “other aberrations” remain uncorrected and can lead to a blurred retinal image and blurred vision. Collectively these other aberrations can be referred to as higher order aberration, while the aberrations that are typically corrected with spectacles and soft contact lenses are referred to as lower order aberration.

What kinds of higher order aberrations are present in keratoconus:

Pantanelli et al. have stated that the level of higher order aberration present in an eye with keratoconus is, on average, approximately 5.5 times higher than the level experienced in a control group. In an effort to visualize higher-order aberration data, they are commonly represented graphically as shown in the figures below. Examples of higher order aberration measured in one normal eye are shown in figure A, while an example of higher order aberration from one keratoconic eye are shown in figure B. The circular nature of the map denotes the boundary of the measurement, which is defined by the round pupil of the eye. A majority of the higher order aberration map in figure A is green (denoting a relative absence of higher order aberration). However, the map in figure B displays a much larger variation in color, indicating the presence of higher order aberration in this individual keratoconic eye in a greater quantity than the normal eye shown in figure A.

Figure A - normal-keratoconus — Figure A – normal

Figure B - keratoconus — Figure B – keratoconus

A wavefront aberration map of the “other aberrations” or higher order aberrations of two eyes. Figure A is an example of data for a normal eye and figure B is an example of data for an eye with keratoconus.

If refraction is not capable of quantifying higher order aberrations, how are they measured?

One method for obtaining the information regarding higher order aberration shown above is with a wavefront sensor. The wavefront sensor objectively (without patient feedback) collects information on the optical performance of the eye that can be used to calculate the amount of both lower and higher order aberration present.

Laboratory-based research related to custom contact lenses:

Several investigators in the laboratory (e.g. Katsoulos et al., Sabesan et al., Chen et al., Marsack et al.) have reported on work that attempts to further reduce higher order aberration by targeting the eye-specific higher order aberration seen in a given keratoconic eye. The general philosophy behind these customized lenses is that the aberration pattern measured with the wavefront sensor is a more complete optical prescription for implementation of a custom contact lens. Figure C demonstrates, in principle, the optical properties of a contact lens designed to correct the higher-order aberration in figure B. Where the map of the eye (figure B) is red, the map of the correction (figure C) is blue, and vice versa. When the lens is worn, the net effect as light propagates through the lens-eye system is the cancellation of the higher order aberration in a targeted manner.

In principle, this figure pictorially represents the higher order optical properties of a contact lens designed to fully correct the higher-order aberration of the eye represented in figure B.

What is next:

Investigators continue to push the technology behind custom contact lenses for keratoconus towards clinical relevance. However, like every novel intervention strategy, we must manage our expectations. Complexity in measuring keratoconic eyes, a need for specialized equipment and expertise to design and manufacture the lenses, the infrastructure needed to coordinate the clinical exam and manufacture efforts and cost associated with the process are a subset of the barriers that must be removed if this type of correction is to become more mainstream. For this reason, it is my opinion that if/when these corrections become commonly available in the clinic, they will likely add to, and not replace, existing forms of corrections that patients and clinicians now utilize to correct vision.

Jason Marsack, PhD
Research Assistant Professor
University of Houston, College of Optometry.
Dr. Marsack’s work focuses on the relationship between visual performance
and optical aberration in individuals with highly aberrated eyes.

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