Even with all the advancements in multifocal implants and soft contact lenses, monovision is often still the preferred method of correction for the presbyopic population. Monovision is when we correct one eye (typically the dominant) for distance, and one eye for near (non-dominant). Depending on the amount of anisometropia (difference in the prescriptions between the eyes), there can be some loss of depth perception. If the monovision discrepancy is kept to a minimum, the brain is able to blend the two fields well and adaptation is typically very easy.
The reason some patients don't adapt well to multifocals is because they tend to degrade the contrast sensitivity of the vision at ALL distances. In contact lenses and IOLs (Intraocular lenses), the lens moves with eye at all times, so there must be both the near and distance prescription in the aperature window to enable the multifocal effect. This doubling or overlay of the optics may cause some "shadowing" or "ghosting" of the image in question. Overtime most individuals will adapt to this, but will still measure a reduction in their contrast sensitivity threshold.
We've been very successful with monovision Ortho-K, soft contacts, and gas permeable lenses in our office. We will fully correct the distance eye and slightly under correct the reading eye (or overcorrect in the case of farsightedness) to provide good vision at all distances. Most patients are happy enough with this that they no longer use glasses for any activities.
Call us at 407-647-2020 if you'd like to schedule an appointment to be evaluated for monovision.
See better, live better
Orthokeratology (Ortho-K): Correct your vision while you sleep.... I swear it's not some voodoo ancient ritual thing
Orthokeratology (OrthoK) is the science of reshaping the cornea to correct ametropias (nearsightedness, or myopia, farsightedness or hyperopia and astigmatism).
The way it works is as follows: Your eye doctor designs a corneal mold (similar to a gas permeable lens )based on your eyeglass prescription and your corneal shape. The corneal mold is then inserted before bed, and reshapes the cornea to correct your vision while you sleep! The molds are then removed in the morning and the wearer can enjoy great vision throughout the day without wearing contacts or glasses.
OrthoK has been around for longer than LASIK, and for those who aren't a candidate, or who aren't interested in the permanent risks of the procedure, OrthoK may be a viable option to correcting your vision.
The real magic of OrthoK is in the great ability of the mold to slow the progression of myopia (nearsightedness). Traditional glasses in kids do correct the central vision, however they create a farsighted peripheral defocus on the retina that stimulates the eye to grow longer over time to "catch up" to the peripheral defocus. The figure below explains this pretty well.(http://www.cvs.rochester.edu/yoonlab/research/mpc.html)
OrthoK induces a myopic defocus in the periphery of the retina to help slow progression through the incorporation of a reverse or relief curve in the corneal mold (red ring featured below). This curve is what slows down the myopia and isn't possible to create with soft contacts or glasses at this time (development with soft lenses is happening, but is won't be customizable like our OrthoK designs).
The initial cost of OrthoK is certainly higher than that of soft contacts or glasses, but is only a fraction of what someone would spend on LASIK. The other great thing about OrthoK is that we can adjust the curvature of the molds overtime to account for the onset changing visual needs for those over 40 who are struggling with their near vision also. We can adjust one eye for near vision (monovision) or adjust both (multifocal).
If you'd like to discuss OrthoK more or are unsure of whether or not you're a good candidate, give us a call.
See well friends,
Contact lenses have come such a long way in the past 100 years The original lenses were made of glass and were very large, very uncomfortable, and very rare. With the advent of PMMA contact lenses (the original hard lenses), contact lenses took off in the 60s and their growth and usage increased dramatically with the onset of gas-permeable and soft lenses.
Gas permeable lenses dominated much of the 70's and 80's, but lost significant ground in the last 2 decades with the advancement of soft lenses. Most contact lens specialists prefer to fit Gas Permeable lenses (GPs) over soft lenses due to the excellent optics of the lenses, longevity, and corneal health benefits. Patients on the other hand typically have rejected them due to the initial discomfort of the lenses.
Until recently, GPs have been primarily designed with only 3 or 4 curves in the lenses. Your doctor would take a small 3mm measurement of the center of your cornea, and then ask the lab to create a GP lens of anywhere from 8-9.5mm in size. How have we measured the rest of the cornea to fit the GP lens you might wonder? Simply put, we guessed, ordered the lens, checked the fit, and then made a series of one or many adjustments until we found we had the appropriate fit.
The problem with fitting gas permeable contact lenses, is that we are often trying to adjust the back curvature of the lens, to optimize the tear "lens" between the contact and the cornea. This tear lens however, is invisible to us whenever the size decreases below the 20um level. Another issue we have when designing gas permeable lenses are the manufacturer's limitations on fabrication. Many labs have basic lathes that can only cut a 3 or 4 curve lens, however some of the most sophisticated labs have lathes that have the potential to cut hundreds of curves over the surface of the lenses. Unfortunately most of those labs don't utilize the full capability of the lathes, and still cut the traditional 3 and 4 curve lenses of the past.
With WAVE contact lenses we can now create hundreds of curves on a single lens which allow for a more optimal fit with better tear coverage and corneal alignment. We are fortunate enough to work with a fantastic lab that has the ability to produce these lenses.
With all the technology necessary and difficulty in fitting the gas permeable lens, why would we bother to do so? This is often a question I get from soft contact lens wearers who aren't familiar with any other modality. There a multiple reasons why corneal gp lenses can be a much better option than soft contact lenses.
Vision - Its very difficult to find a soft contact or even a spectacle lens that can compete with the fantastic vision offered by a well fit corneal gas permeable lens. This is due to the fact that the GPs correct the irregularities of the cornea with amazing thin lens tear optics. The tears that fill in behind the lens and the cornea create a custom refracting surface which "sphericalizes" the corneal surface, creating a near perfect refracting lens.
Health - Corneal GP lenses are typically the most healthy option for the eye as well for a multitude of reasons. One of the most important aspects of corneal health that is often ignored by many practitioners is the area of the limbal stem cells just on the periphery of the cornea. These stem cells are responsible for constantly healing the surface stress of the cornea on a daily basis. Soft lenses typically hug the limbal stem cell area and can cause compression and oxygen deprivation. Because GP lenses typically are smaller in size than the cornea, they do not exert pressure on the limbal stem cells.
Comfort - Yes, without a doubt, soft lenses are initially much more comfortable than gas permeable lenses upon insertion. However, given a few days and weeks in corneal gas permeable lenses, most patients will report great comfort. In my experience, it is much more common for patients to complain about dryness with their soft lenses than those patients who wear gas permeable lenses. After the initial adaptation period with GP lenses, most patients will not complain about comfort and can wear their corneal lenses comfortably for most of the day.
If you haven't tried contacts in a while, or have been unhappy with your soft lenses and would like to consider trying GP lenses, feel free to mention it to either myself or Dr. Giedd at your next appointment and we'd be glad to discuss it with you further.
See better and live better,
At this time, most of the research surrounding glaucoma (primary open angle) indicates that damage to the optic nerve is related to either elevated IOP, vascular dysregulation, or a combination of the two.
Our treatment protocols for maintaining vision and slowing the progression of glaucoma have always centered around reducing IOP (Intra-ocular pressure). This reduction in IOP is usually accomplished with drops, laser, or in the most advanced cases surgery.
I was soooo excited (for a few reasons below) when I came across the article in the Ophthalmology section of JAMA (March 2016, Vol 134:3) entitled
"Association of Dietary Nitrate Intake With Primary Open-Angle Glaucoma A Prospective Analysis From the Nurses’ Health Study and Health Professionals Follow-up Study."
1. In all of the training I've been through, I've never heard of any reduced risk or protection for glaucoma based on dietary recommendations (and I trained with some of the nation's top glaucoma gurus at the VA as well as NOVA SouthEastern University).
2. As a nutritionally conscience person, I'm so happy to see evidence continuing to accumulate for a leafy-green heavy diet.
3. Finally, now I have some nutritional advice I can offer those suffering from Glaucoma that may actually lower their risk of losing central vision along with the IOP medications we prescribe.
In a nutshell, the author's who reviewed specific characteristics of the longterm landmark NURSES' Health Study found that the more Leafy greens you eat, the lower your risk of glaucoma, and specifically the lower your risk of central vision loss from glaucoma. We aren't just talking a small decrease in risk here either, we are talking large statistical drops of 20-30% for POAG (Primary Open Angle Glaucoma) and nearly a drop of 40-50% for those with paracentral visual field loss at diagnosis.
The gist of this is due to the amazing way your body and eyes work in the presence of good leafy stuff. Leafy greens are chock full of naturally occurring nitrates, which get converted in your body to nitric oxide through very elaborate biochemical pathway that people smarter than I understand. The Nitric Oxide molecules dilate blood vessels, allowing for increased tissue oxygenation to occur. This increase in oxygenation helps to protect the small tiny blood vessels that feed your optic nerve tissue, thus slowing or inhibiting part of the damaging processes that occur during glaucoma.
Wait a minute, aren't nitrates bad for you? Well, if you do some Dr. Google research you'll find that sodium nitrites (normally found in preserved meats like hot dogs, jerky, etc) are potentially carcinogenic, however these synthetic nitrites behave very differently from those naturally occurring forms of nitrates that are found in vegetative matter. Though they sound the same, they aren't.
Natural Nitrates = Good
Synthetic Nitrites = Bad
Let's not forget the copious amount research indicating the protective function of leafy greens and macular degeneration either (another post for another day : ).
If able, we all could benefit from more leafy greens (those on blood thinners may not be able to, so ask your pcp or cardiologist if this applies to you). In short, eating lots of green vegetation is the best nutritional thing you can do for your eyes. This simple dietary advice will help you lose weight and reduce your risk of developing glaucoma, one of the world's top causes of incurable blindness.
Unsure if you have glaucoma, or haven't been checked recently? Call our office at 407 647 2020 to schedule an appointment!