Preserving your eyesight as you age
AN APPLE A DAY - Tyrone M. Reyes M.D. (The Philippine Star) - June 1, 2015 - 10:00am

“If there’s a true measure of a person’s soul, if there is a single gauge of real divinity, of how beautiful a fellow human honors this life …. it has to be right there, in the eyes.”                                                               

Mark Monford

 

Clear sight helps you to stay safe, alerting you to danger and the unexpected.  On an emotional level, your vision helps you define who you are, how you interact with others, and how you interpret facial expressions and body language.

As you age, though, changes can occur in the delicate structures of your eyes and these changes can affect your vision. You may experience only minor problems, such as being unable to focus on close objects, or more serious eye problems, such as cataracts, glaucoma or macular degeneration.

Last year, the Philippine Academy of Ophthalmology estimated that as many as 2.4 million Filipinos would develop visual impairment during the year, primarily due to error of refraction, cataract, glaucoma, retinopathies (particularly those secondary to diabetes and hypertension), and age-related macular degeneration.

The good news is that many age-related eye problems can be managed or treated with a broad array of ever-evolving medical devices and technologies, from inexpensive eyeglasses to state-of-the-art surgery.  And although not every eye problem can be avoided, common-sense preventive measures, such as wearing sunglasses and regularly visiting your eye doctor, can preserve the health of your eyes as you age. 

How you see

The complexity and sophistication of human vision is unrivaled, even with the advent of the digital camera and 3-D television.  One reason that your eyes are far superior to any existing technology is that they’re made of living tissue.  Your eyes move and function together in perfect synchronization.  Each eyeball makes many rapid adjustments for brightness, focus, and internal pressure.

When you look at an object, the image is rapidly transmitted to your brain.  That journey of an image to your brain includes the following steps (see diagram):

•  Light passes through your cornea.  Your cornea is a domed layer of crystal-clear tissue that covers the front of your eye.  Its convex surface bends incoming light and begins the process of focusing the light rays from objects in front of you.

• Light is directed through your pupil.  Once light is transmitted through the cornea, it’s streamlined through your pupil, the black area in the middle of your iris.  The iris is the colored part of your eye.  This ring of tissue includes some pigment and small muscle fibers that expand and contract to regulate the amount of light that is let in, through the pupil.

• Your crystalline lens fine-tunes the focus.  The lens of your eye is a clear, elliptical structure located behind the iris and the pupil.  The lens fine-tunes the focus of light that has passed through the pupil.  A circular muscle that surrounds the lens can relax and contract, and change the lens curvature so as to sharpen the focus of light on the retina.

• Your retina transforms light into electrical impulses.  Located at the back of your eyeball, your retina consists of millions of light-sensitive cells.  When light strikes the retina, it induces a chemical reaction.  This reaction generates electrical impulses that are relayed through the eye’s optic nerve to the visual cortex, the seeing part of your brain.

• Your brain “sees” the image. Because of the convex shape of the cornea and the lens, the image your retina receives is upside-down and reversed.  Your brain flips and turns the image and blends the slightly different viewing angles from both eyes into a real-time stream of colorful, 3-D images.

Age-related eye problems

Starting at about age 40, some eye problems become more common. But in general, you don’t have to sit back and accept them as part of getting older. There are a variety of measures you can take to minimize or even prevent the effects of age on different eye conditions, including:

• Presbyopia.  If you find yourself frequently holding your book out at arm’s length in order to read, chances are you’re experiencing the initial signs and symptoms of presbyopia.  By age 40, the eye’s lens is less flexible, making it harder for your eyes to focus clearly on close objects and to quickly adjust between near and far.  Most people eventually develop some degree of presbyopia.

In many cases, wearing corrective eyeglasses is the simplest way to manage presbyopia.  If you already wear corrective lenses, your eye doctor may recommend bifocals.  Bifocals have a higher focusing power in the lower part of the lenses.  Trifocals can provide corrections for close, intermediate, and distance vision. Or if you wear contact lenses for distance correction, you might wear reading glasses in addition to the contacts.  Until about 65 or so, your eyes continue to change, so you’ll likely need periodic changes in your prescription.  After age 70, the lenses of your eyes will have lost almost all elasticity, so you’re less likely to require prescription changes.

•  Cataracts. A cataract is a clouding of the lens in your eye. As you age, your lens becomes stiffer, thicker, and less transparent.  Protein fibers in the lens break down, clump together and start to take on a whitish or yellow-brown color. The process is painless and gradual and can develop in one or both eyes.  But the resulting cloudiness changes the refractive ability of your lens, so the light entering your eyes is scattered and the lens can’t project a sharp, focused image onto your retina. The result is increasingly blurred vision, often combined with sensitivity to bright light and glare.  Most people over 60 have some degree of cataract formation.

In general, a cataract isn’t harmful to the health of your eye. In the early stages, your doctor may recommend a new eyeglass prescription or a magnifying glass to increase the sharpness of your vision. Wearing full-spectrum ultraviolet (UV) protection sunglasses and brimmed hats can decrease glare. Because cataracts tend to progress, it’s important that you have regular follow-up visits with your eye doctor.  This allows you and your doctor to monitor the cataract and make informed decisions about further treatment.

In some cases, a cataract may eventually disrupt your vision enough to affect your quality of life and independence.  At this point, you may wish to have the cataract removed and replaced with a clear, artificial lens implant.  Your eye doctor can help you decide whether and when cataract surgery would be a good choice for you.  Cataract surgery today is usually an outpatient procedure lasting less than an hour.  Typically, you need only a local anesthetic, which means you’re awake during the operation. After surgery, you usually can resume normal activities by the evening of the same day.  It takes about four to six weeks for the eyes to heal completely.  Once your eyes have healed, your eye doctor can assess your need for eyeglasses or contact lenses. Most people need eyeglasses after cataract surgery, at least for some activities.

Cataract surgery leads to improved vision in about 90 percent of people who have it, and complications are uncommon. But risks do exist, including inflammation, bleeding, swelling, retinal detachment, increased pressure inside the eye, and lens dislocation. It’s important to discuss both the risks and the benefits of cataract surgery with your eye doctor or surgeon before proceeding with the operation.

• Age-related macular degeneration. Age-related macular degeneration (AMD) is a chronic eye disorder that occurs more commonly after age 50.  It results primarily in the loss of central vision.  It’s marked by the deterioration of the macula, a spot of densely packed specialized cells centered at the back of your retina.  These cells allow you to see color and fine detail. Damage to these cells can leave you with a blind spot in the central portion of your vision.

There are two types of AMD — dry and wet.  With dry AMD, initial changes occur in the retinal pigment epithelium (RPE), a thin layer of tissue sandwiched between the photosensitive cells of the retina and a layer of the blood vessels. The RPE forms the outermost surface of the retina and provides a critical passageway for nutrients and waste products between the retina and the choroid.  As the eyes age, cells in the RPE begin to deteriorate (atrophy) and lose their pigment.  As a consequence, the RPE becomes less efficient in removing waste.  Clumps of waste deposit and the resultant mottled pigmentation under the retina interfere with the light-sensitive cells in the macula, causing patchy loss of vision.

Most people with macular degeneration have the dry form. Dry AMD tends to progress slowly, and some people may not be bothered by it unless they live to a very old age.  Although there’s no specific treatment for dry AMD, there’s evidence that certain vitamins and minerals in your diet may help slow its progression.

Although wet AMD accounts for only 10 to 15 percent of AMD cases, it accounts for about 80 percent of severe vision loss in people with AMD.  Wet AMD also progresses much more rapidly than dry AMD.  If you notice dark spots in the center of your vision or wavy visual distortions, these may be signs of wet AMD.  See your eye doctor promptly.  Early diagnosis and treatment can stop or slow the disease’s progression, providing you an opportunity to preserve as much vision as possible. 

Bottom line: Visit your eye doctor!

One of the best ways of preserving your vision as you age is by having regular exams.  Periodic visits to your eye doctor help detect eye problems early and make sure your vision is the best it can be.

 

 

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