What is the difference between nearsighted and farsighted?

           

Nearsighted (myopia) means the focusing system of the eye is too strong or the axial length of the eye is slightly too long such that the image is in focus in front of the retina instead of in perfect focus on the fovea of the retina. Patients with this kind of prescription are able to see well up close but things at distance are out of focus.

 

Farsighted (hyperopia) means the focusing system of the eye is too weak or the axial length of the eye is slightly too short such that the image is in focus behind the eye instead of in perfect focus on the fovea of the retina. Patients with this kind of prescription are able to see far away but have difficulty and strain while reading. At a young age, the human lens in the eye can adjust and compensate somewhat for this kind of refractive error so younger patients might not experience any symptoms. Around the age of forty as presbyopia sets in the lens becomes less flexible and can no longer adjust to overcome this focusing deficit and the patient will become much more symptomatic for reading. Depending on the amount of hyperopia the patient might also have difficulty seeing at both distance and reading as the lens inside the eye continues to stiffen throughout the forties and the fifties. 

 

What is an astigmatism?

 

An astigmatism is a type of refractive error resulting when the lens in the eye or the cornea is slightly steeper or more curved along one direction than along another (e.g., steeper vertically and flatter horizontally). This difference in curvature on the cornea or lens is not cosmetically noticeable and the resulting refractive error can be corrected with glasses. The image is mis-focused such that only a part of the image is in focus on the fovea of the retina. Patients with this kind of prescription can experience distortion in their vision at distance and up close. 

 

What is presbyopia?

 

Presbyopia is an age-related change in the lens of the eye in which the lens becomes thicker and more stiff starting in the late thirties and progressing with age. As the lens becomes less flexible, the eye can no longer adjust quickly from reading to distance or visa versa and at some point the patient experiencing presbyopic changes can no longer adjust their eyes to read without the aid of reading glasses. The strength of reading prescription required typically increases with age or with closer reading distances. Because the eye is comprised of smooth muscle, wearing or not wearing reading glasses has no bearing on this age-related change to the eye. In other words, wearing reading glasses will not make the eye "weaker" or more reliant on reading glasses. Unless a person is nearsighted and needs to use glasses for distance, everyone has to use reading glasses at some point over the age of forty.  

 

Do I really need an eye exam once a year?

​

Yes! Many diseases that cause loss of vision like glaucoma and macular degeneration are painless and have no symptoms in the beginning stages. Having an annual eye exam can help catch many treatable ocular diseases as well as monitor systemic diseases. The eyes are an extension of the brain and provide the only means of examining blood vessels without invasive surgery. Because of this, eye care practitioners are often first to diagnose things like: diabetes, autoimmune diseases, hypertension, high cholesterol, tumor cells, melanomas, and a myriad of other systemic issues. It is very important to have your eyes examined annually (at least) as it is an excellent diagnostic tool for overall health in addition to maintaining healthy eyes and clear vision. 

 

Are carrots really good for your vision?

​

​Carrots contain high levels of vitamin A or retinoic acid which the rod photo receptor cells need in order to provide adequate night (or low illumination) vision. Patients deficient in vitamin A can experience night blindness, or an inability to see in low light levels. It is very uncommon for people in developed countries to be deficient in vitamin A in levels low enough to result in night blindness. Carrots will not hurt your eyes and certainly have many nutritious benefits, but won't necessarily improve your vision unless you have an extreme deficiency of vitamin A. The best food for your eyes are actually dark green leafy vegetables and other foods high in antioxidants and lutein. Eating these kinds of foods help the protective pigments in your eyes and help prevent loss of vision later in life from diseases like macular degeneration. 

 

Is it bad to use over-the-counter reading glasses?

 

Because the eye is comprised of smooth muscle, wearing or not wearing reading glasses has no bearing on age-related changes to the eye, or presbyopia. In other words, wearing reading glasses will not make the eye "weaker" or more reliant on reading glasses. Unless a person is nearsighted and needs to use glasses for distance, everyone has to use reading glasses at some point over the age of forty. Prescription reading glasses that correct the eyes for each person's individual focusing needs are in many ways superior.

 

If I do use over-the-counter reading glasses, what power should I use?

 

If you read at a 40 cm working distance (about 16 inches) the strength required for reading is related to age (assuming you are not nearsighted or farsighted). The chart below may approximate the power appropriate for over-the-counter reading glasses:

Age 40-45: +1.00 or +1.25 

Age 45-50: +1.50 or +1.75

Age 50-55: +2.00 or +2.25

Age 55 and up : +2.50

 

What is a cataract?

​

A cataract is a yellowing and clouding of the lens in the eye due to aging, sun exposure, or sometimes medications and toxins in the body. Most people develop the beginning of cataracts in their fifties and as the lens fibers continue to change the vision will slowly degrade until cataract surgery is required. Cataract surgery is an outpatient procedure typically covered by medical insurance and is considered fairly routine. Most people get cataract surgery at some point in their sixties, seventies, or eighties depending on some genetic and environmental factors.

​

What are Blue Light Blocking Glasses and should I get them?

 

Visible light spectrum for the human eye goes from about 380 nm (blue/violet light) to around 750 nm (red/orange light). Blue and violet light is in the small wavelength, high energy portion of the spectrum and is found in high quantities in computer screens, handheld devices, and anything using LED technology. Excessive exposure to this kind of light can cause fatigue, strain, disruption of circadian rhythm, earlier onset of cataracts, and possibly damage to the retina over time. Research and clinical studies demonstrate exposure to blue wavelength light after sundown causes sleep disruption due to changes in circadian rhythm. Several other studies demonstrate the deleterious effects of long term exposure to blue light on animal retinas. More ongoing research is needed to discover whether this is the case in humans but there is increasing interest in "blue light blocking" technology in an effort to prevent any possible damage that might occur from increased use of blue light devices. Spectacle lenses with a slight yellow tint will block light in the blue end of the visible light spectrum and are available at any optical retailer and are usually called "blue blocking" glasses. Additionally, blue light filter options are available on many cell phone and computer settings. For more reading on clinical studies about blue light effects on the eye please see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288536/

​

What can be done to slow my child's progression of myopia (nearsightedness) and glasses prescription from increasing?

​

More conclusive research needs to be done to determine the best method to control myopia. A number of clinical trials have shown support for various methods of creating enough mis-focus or blur in the periphery of a child's retina. This is thought to slow the elongation of the retina that is partially responsible for worsening nearsightedness in kids. Using a daily regimen of certain eyedrops to relax the iris, bifocal contacts or bifocal glasses, orthokeratology contacts are among the current treatment options available for parents interested in attempting to prevent severe myopia in their children. These methods have stabilized nearsighted prescriptions in some cases and shown mild but "clinically significant" prevention of myopic progression in some groups of children. Taking breaks and/or increasing reading distance from devices like phones, tables, computers, and books is universally considered beneficial in preventing eyestrain and can possible help to slow myopic progression. The link below provides more information on the prevent of progression of myopia.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6313317/

​

Why is it bad to sleep in my contacts?

 

Like any part of your body, the cornea of the eye needs oxygen for the immune system to function properly. If contact lenses are over worn or slept in repeatedly, the oxygen supply of the eye will diminish and leave the cornea susceptible for an infection. It may be unappetizing to consider, but bacteria live on our skin, eyelids and eyelashes and if it gets into the eye, it's important for the immune system of the eye to be able to fight off the impending infection. Sleeping in contact lenses creates the perfect environment for bacterial growth, like a petri dish. If bacteria invade the top layer of the cornea, a very painful infection with ensue and can result in scarring and vision loss. 

​

How may Coronavirus (COVID-19) affect the Eye?

 

Viral transmission can occur through the conjunctiva (lining of the eyelids and whites of the eye) as it is a mucus membrane similar to the lining of the nose and mouth. Touching the eyes should be avoided as much as possible and only after sufficient hand-washing with soap. Contact lens wearers should be especially diligent about removing contact lenses at night to avoid extra risk of infection and inflammation of the eyes. Possible ocular symptoms of COVID-19 may include increased risk of: conjunctivitis, corneal ulcers, iritis, and uveitis. Visible ocular redness and inflammation of the eyes may be associated with Kawasaki's Disease which has been documented in rare cases in COVID-19 patients. Any of the above symptoms warrant a visit to the eye care professional to diagnose, treat, and ascertain the underlying cause.