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Cataract – An infographic by GeriatricNursing.org
If you or a loved one has cataracts, you’ll want to know what these are all about. Cataracts are basically areas of opaqueness or cloudiness of the lens of the eye. Normally, the lens is clear and allows for a full amount of light and clear images to pass through to the retina of the eye. Cataracts can be small areas of opacity or can involve the entire lens and can affect normal vision. The majority of cataracts develop in individuals 55 years of age or older; however, certain kinds are congenital (occurring at birth) or can happen after a traumatic injury. Cataracts generally affect both eyes roughly the same but one eye is often more involved that the other with vision loss.
The healthy lens is located behind the iris or colored part of the eye. It focuses light (similar to a camera lens) on the retina, which sends the image to the brain through the optic nerve. The brain then interprets the image. The lens is usually completely transparent so clear images are sent to the retina. If the lens becomes opaque from a cataract, it cannot send a clear image to the retina, and your vision will be blurry.
SIGNS AND SYMPTOMS OF CATARACTS
In general, cataracts don’t develop overnight and instead develop very slowly. As it develops, the typical symptoms you’ll notice include the onset of hazy or blurry vision, an increased amount of glare from headlights and other lights at night, a deceased vibrancy of colors, changes in refraction (nearsightedness or farsightedness), and difficulty seeing things in a darkened environment. Once these symptoms begin, they progressively get worse. There are no medications or eyedrops that can slow the progression of the disease. Ultimately, when the vision worsens, surgery is the only option.
RISK FACTORS FOR CATARACTS
There are several risk factors for cataracts. The greatest risk factor is advanced age. By the age of 80, almost everyone will have some degree of cataracts or will have already had cataract surgery. People who are obese or who have diabetes have a greater chance of having cataracts. Excessive sunlight exposure increases the risk of cataracts so sunglasses can make a difference between getting cataracts and not getting cataracts. Smokers have a greater risk of cataracts. Hypertension will increase the risk. Individuals who have had an eye injury or inflammatory disease of the eye will carry a higher risk for cataracts. Past eye surgery will increase the risk of developing cataracts.
Cataracts are so common that it is the most common cause of blindness throughout the world. Most of the affected patients live in developing countries where surgical options are limited. The treatment of cataracts involves detecting the cataracts early, monitoring them regularly, and performing surgery when the vision is significantly impaired, which is something not available in developing countries. If these things can be accomplished, the vision loss is very reversible, even in its advanced stages.
CAUSES OF CATARACTS
The underlying cause and pathology behind most cataracts are not completely known. It appears to have nutritional, genetic, and environmental factors. As an individual gets older, the thickness and weight of the lens increases, while its ability to accommodate to visual demands worsens. The central nucleus (inner portion) of the lens gets pressed by new layers added to the lens, decreasing its lucency.
There are age-related changes in the epithelium of the lens so that the epithelium (lining of the lens) decreases in thickness, leading to fibrosis or scar tissue on the lens surface, decreasing the transparency of the lens. The older lens takes on water more slowly and takes up metabolites with less efficiency. This includes having a decrease in the numbers of antioxidants that can get into the cells. The cells develop damage from oxidative stress, leading to cataract damage. Damaging free radicals in the cells (like iodized glutathione) have been found in cells that are affected by cataracts.
The other factor that might lead to cataracts is the precipitation of smaller proteins into larger aggregates of proteins that light cannot pass through. These large protein matrixes are not soluble in water and serve to scatter light rays in the lens, reducing the lens’ ability to have a clear image pass through it.
There are three different types of senile (old-age) cataracts: 1) cortical cataracts; 2) nuclear cataracts; and 3) posterior subcapsular cataracts. Cortical cataracts come from changes in the salt content of the cortex (outer layers) of the lens that produce fibers that can’t let light through. Nuclear cataracts come from excessive amounts of scar tissue that causes a yellow to brown-colored nucleus (the central part of the cataract). Posterior subcapsular cataracts come from granular deposits and plaques in the posterior subcapsular cortex (in the back of the lens) so that light cannot pass through the lens. The treatment of all three types of cataracts is the same.
Age-related cataracts have multifactorial causes, including environmental factors, UV light exposure, dietary factors, and advanced age. Causes of cortical and posterior subcapsular cataracts are more related to having diabetes, taking certain drugs, and being exposed to UV light when compared to nuclear cataracts. Nuclear cataracts, on the other hand, are most related to being a smoker. Alcohol abuse seems to cause all types of cataracts.
As for drugs causing cataracts, being under general anesthesia and taking sedatives are linked to cortical cataracts, while steroid use and high sugar levels are associated with posterior subcortical cataracts. Nuclear cataracts are linked to drinking milk and taking calcitonin. Mixed cataracts seem to be associated with having had general anesthesia in the past.
There are several systemic diseases that are linked to cataracts, such as having gallstones, having high blood pressure, being mentally retarded, and having diabetes. Hypertension is especially linked to having posterior subcortical cataracts. Having high triglycerides, high sugar levels, and diabetes are connected to having this type of cataract at an early age in life.
It is believed that UV light caused thermal (heat-related) injuries to the lenses. Exposure to the sun raises the body temperature and the temperature of the eye so that proteins that aren’t supposed to coagulate become bound together. It has been found that people who live in areas of the world with a lot of UV light exposure have a higher incidence of age-related cataracts than people who have lesser exposure to UV light.
EPIDEMIOLOGY OF AGE-RELATED CATARACTS
The rates of the different types of cataracts are different but they all increase in frequency with age. In people older than 75 years of age, the incidence of nuclear cataracts is 65 percent; the incidence of cortical cataracts is 28 percent; and the incidence of posterior subcapsular cataracts is 20 percent. About 17 percent of people older than aged forty years have at least some degree of cataract formation in at least one eye. About 3 million people in the US have cataract surgery. The success rate of this type of surgery is about 95 percent (which means the vision was at least 20/20-20/40).
In other parts of the world, cataracts are a leading cause of blindness. The highest rate of visual impairment in the world from cataracts is in India. About 1 percent of all Africans are blind with more than a third of them having cataracts as a cause of their blindness. The research in rural India shows a cataract incidence of 67 percent in those aged 70 years or more.
Failure surgically remove a cataract and replace it with an implant can cause swelling of the lens, secondary glaucoma, and ultimately to blindness. There is no risk of death from cataract extraction as the surgery is done with local anesthesia. There is a higher percentage of cataracts in blacks but this is not felt to be hereditary. It is more related to an increased lifetime incidence of diabetes and possible occupational exposure to UV radiation. There is a slightly higher incidence of cataracts in females versus males. (17 percent versus 13 percent).
Age is the main factor that leads to senile cataracts. As the person ages, there is an increased chance of developing a senile cataract. The total number of cataracts in people aged 45-64 years is 23 cases out of 100,000 individuals. The total number of cataracts in people aged 83 years and greater is about 490 cases out of 100,000 persons.
A traumatic cataract usually forms in one eye after a blunt or penetrating injury to the eye. Less common causes include exposure to infrared energy, ionizing radiation exposure, and electric shocks—each of which is largely an occupational exposure.
Blunt trauma to the eye forms a rosette-shaped or stellate-shaped (star-shaped) area of opacity in the lens, obscuring the vision. The opacity may stay the same or may progress to involve more of the lens. Penetrating trauma usually disrupts the capsule of the lens, causing changes that may stay the same over time or, like blunt trauma, may progress to cause cortical opacification of the entire lens.
Besides the actual traumatic lesion on the lens, there is a high risk of lens dislocation (displacement of the lens) associated with having a traumatic cataract. Glaucoma can be a side effect as well as a hyphema (bleeding in front of the lens) and other hemorrhaging in the eye. The entire globe of the eye can rupture. Each of these can contribute to becoming blind after a traumatic injury.
The cause of a traumatic cataract involves what’s called a coup and contracoup eye injury. The coup part of the injury is the direct blow to the eye. It’s caused by whatever injured the eye and is in the front of the lens. A contracoup injury stems from shock waves that damage other parts of the lens through the traveling of these shockwaves throughout the lens.
There can be stretching of the lens capsule from the blow that disrupts the capsule and other parts of the lens so that there are cataract changes in the eye that weren’t directly involved in the traumatic injury in the beginning. In penetrating injuries to the lens, the entire lens becomes damaged if the hole in the lens is big enough. Fortunately, small holes can seal themselves up and there will just be localized damage to the capsule of the lens.
EPIDEMIOLOGY OF TRAUMATIC CATARACTS
There are about 2.5 million eye injuries in the US per year, accounting for 5 percent of ophthalmology visits. Traumatic cataracts can be acute injuries, subacute findings, or late sequelae of an eye injury. It depends on the nature of the injury and how the original opacification spreads. Trauma is the leading cause of blindness in one eye in people under the age of 45 years. Having a posterior segment injury (a deeper injury) leads to a greater chance of blindness when compared to more superficial (anterior segment) injuries. The male-to-female incidence of eye trauma such as a traumatic cataract injury is about 4: 1. Most injuries are work-related or sports-related injuries.
These involve lens opacifications that happen prior to birth and that show up at the time of birth. They need urgent treatment because, if they aren’t detected and treated early in life, there will be permanent loss of vision. Not all congenital cataracts are deemed significant visually. They occur in the periphery of the lens and don’t necessarily need treatment. Only those that affect the visual line of sight need treatment. Small cataracts in the periphery or in the anterior capsule of the eye may be tolerated without actual loss of vision.
There are several causes of congenital cataracts. Unilateral cataracts (in just one eye) are sporadic and associated with several development problems in the eye or with things like rubella contracted in utero. As for bilateral cataracts, these are often hereditary and linked to other disorders. A full infectious disease, genetic, metabolic, and systemic workup is necessary as there are a number of disorders associated with bilateral cataracts. These include the various trisomy syndromes (like Edward syndrome and Down syndrome), congenital hypoglycemia, myotonic dystrophy and the various TORCH diseases (such as toxoplasmosis, rubella, herpes simplex, and cytomegalovirus). Premature babies have a higher risk of congenital cataracts.
CAUSES OF CONGENITAL CATARACTS
The lens develops from an embryonic nucleus at about the sixth week of gestation. Around this nucleus is the fetal nucleus; together these make up the lens by the time of the child’s birth. After birth, there are changes in the cortex of the lens so that the anterior part of the lens becomes the cortex of the lens. Anytime there is an insult to the nuclear fibers of the lens before birth, there will be an opacification or cataract of the lens that comes out of the insult. Any insult prior to the full development of the lens can trigger the formation of a cataract.
There can be an infectious, metabolic, or traumatic insult to the nuclear fibers of the lens that results in opacification (cataract formation) of the medium of the lens. The type of opacification and its pattern can help identify when the insult was to the lens and the possible cause of the insult.
EPIDEMIOLOGY OF CONGENITAL CATARACTS
Congenital cataracts occur in up to six infants out of 10,000 live births in the US. Because of a greater incidence of infections in pregnancy and other insults, the rate of congenital cataracts in developing countries is believed to be much higher, although the actual rate is unknown.
There is a lot of morbidity (illnesses) associated with having congenital cataracts. Babies can have abnormalities like being cross-eyed, getting glaucoma, and having retinal detachment. In bilateral disease, some type of systemic or metabolic problem is often found in these babies. Things like deafness, mental retardation, heart disease, kidney disease, and other systemic diseases can be part of having a congenital cataract.
There are several things to look out for when determining if you or someone you know has a cataract. The most common type of cataract is the age-related or senile cataract so you can expect to find this type of cataract in someone older than 55 years of age. The most common complaint is worsened vision. A cataract is considered clinically important if it affects the person’s vision.
The types of cataracts a person has affects the patient’s visual experience. Slight degrees of cataract formation on the posterior capsular area will cause great disturbances in the vision. Near vision is more affected than far vision because of problems with near vision accommodation. On the other hand, the person with nuclear cataracts have poor distance vision and fairly good near vision. People with cortical cataracts don’t have significant vision loss unless the cataract is very advanced.
Another common problem in the vision of people with cataracts is the phenomenon of glare. There may be glare seen in bright light environment or severe glare from oncoming headlights when trying to drive at night. Glare is mainly seen with posterior subcapsular cataracts and somewhat with cortical cataracts. It isn’t seen to a great degree in patients with nuclear cataracts. Glare alone is not a serious problem and, by itself, isn’t usually serious enough to require surgery.
Cataracts lead to some degree of myopia (near-sightedness). Patients who normally need reading glasses find that they no longer need them (at least for a little while). After a period of time, however, this visual improvement goes away and vision is poor again. Some patients can develop outer cataracts with an inner area of clearing that leads to double vision. The double vision occurs in just one eye and cannot be corrected with contact lenses or other devices.
In looking at a person with glaucoma, they will have deficits in near and far vision. They will test positive for the presence of glare and will have a cataract seen by an ophthalmoscope (eye microscope). A high-grade microscope of the eye should be able to tell the difference between nuclear cataracts, posterior subcapsular cataracts, and cortical cataracts. The eye should be dilated to better see the whole lens.
TREATMENT OF CATARACTS
The only treatment for cataracts is surgical removal of the cataract with intraocular lens (IOL) implantation. Before the surgery, the ophthalmologist will determine the focusing power necessary for your intraocular lens. Eye drops can prevent infection and will reduce swelling during the surgery and afterward so these will be started before the surgical procedure. On the day of surgery, you’ll be asked to fast for 6-8 hours prior to the procedure. The surgery will be done in a hospital or outpatient surgery center.
While the surgery itself lasts only about fifteen minutes, you can expect to be at the surgery center for at least an hour and a half. This is because it takes time for the eyedrops to numb the eye and to give you sedating medications. You will need only a brief period of observation after surgery and will receive postoperative instructions. Someone needs to drive you home after surgery and you will not be able to drive until the surgeon clears you for driving.
The eye is numbed with an injection around the eye or with certain anesthetic eyedrops. Medication to help you feel calmer will be provided as you will be fully awake during the procedure. The surgeon will make small incisions in the front of the eye in order to remove the lens. Many surgeries are done with phacoemulsification. This involves putting an ultrasound device into the middle of the clouded lens so the lens breaks up into tiny pieces. These pieces are gently sucked out of the incisions. A new lens will be placed where the damaged lens once was. No sutures are required as the eye will heal itself. After resting for a half an hour in recovery with the eye patched, you will go home with the patch in place until you see the ophthalmologist again.
After surgery, you will use drops to prevent inflammation of the eye. These may need to be used for several weeks after the procedure. You cannot press on the eye or rub it too hard. Sunglasses might need to be worn to protect the eye from injury. Even if there are cataracts in both eyes, only one eye will be done at a time. No soap or even water can get into the affected eye. A shield will be worn at night to protect the eye in your sleep. Gradually, you can return to normal activities.
One side effect that many people get weeks to years after surgery is called “posterior capsular opacification”. It involves an increase in blurry vision caused by scar tissue in the posterior capsule. The posterior capsule is what holds the new lens in place. This usually means you have to have a laser procedure to create a hole in the capsule so you can see better. This is called a “posterior capsulotomy”.
There are risks to having cataract surgery, but they don’t happen very often. They include getting an eye infection or bleeding, swelling of the front part of the eye, swelling of the retina, ongoing pain, detached retina, loss of vision, or dislocation of the IOL.
If you are covered by Medicare if you are eligible for this type of surgery. Most private insurances cover for cataract surgery as well. Special kinds of IOLs may cost you some out of pocket. It will also cost you out of pocket if you decide to have surgery before your vision actually deteriorates too much. If you don’t have insurance, ask the doctor about a payment plan.
EYE SURGERY RECOVERY
Eye drops are necessary for a few weeks and need to be applied several times per day. You will need to wear a shield when sleeping for a week after the procedure. Sunglasses should be worn when outside. There will be some redness of the eye and blurry vision in the first days after cataract surgery. You’ll have to avoid lifting anything over twenty-five pounds, as well as bending or exercising to excess in the first week postoperatively. Don’t splash water in your eyes as this can cause infection. This means showering and bathing with your eyes closed for a week after surgery. There should be no hot tubs or swimming for two weeks after the procedure and you can’t expose your eye to contaminants like dust or dirt.
The doctor will wait at least 1-3 weeks before attempting to do the second eye. Once the first eye has recovered and sufficiently healed, it should be okay to go ahead and do the other eye. After the second eye heals, you should have reasonably good vision.
Unless you select IOLs that correct presbyopia, you will still need reading glasses after cataract surgery. Even with a premium IOL, it is possible that you won’t be able to see well enough to read newsprint or other fine writing and will still need eyeglasses. Because you might also have some nearsightedness after surgery, you might want to wear progressive lens eyeglasses that allow for far and near vision. Glasses will also protect the eye from injury and some people just feel better with glasses.
The trick is to choose glasses that have an anti-reflective coating and those that are photochromic (get darker in bright lighting like in the sun). Talk to your ophthalmologist or optometrist about these features and about how much these features cost. Because you’ll need some sun protection forever, these types of lenses save you from having to buy prescription sunglasses as well.
LASER CATARACT SURGERY
Lasers that have traditionally been used in LASIK eye surgery have been approved by the US Food and Drug Administration for cataract surgery. Lasers are used in several steps in the cataract removal procedure. It creates the incisions in the cornea so that the surgeon doesn’t have to make any cuts himself. It removes the anterior capsule of the lens and breaks up the cataract with less phacoemulsification energy is necessary to break up the lens prior to its removal. It will also create peripheral corneal incisions at the time of cataract surgery in order to reduce astigmatism (if necessary).
The downside of laser cataract surgery is that it is a fairly new and untested form of surgery that markedly increases the cost of the cataract surgery because just buying the laser device can cost the ophthalmologist up to $500,000 USD. The machine is expensive to use and maintain and this is what adds to the cost of surgery. As it becomes cheaper, it should be done more often because it is safer than regular surgery and provides better visual outcomes with decreased recovery time.
SELECTING AN IOL
IOLs have been approved by the FDA since the early part of the 1980s. Before they were available, people with cataract surgery need to wear glasses or contact lenses in order to have some sort of normal vision. With IOL, the lens that gives you normal vision is implanted directly into the eye.
Today, there is more than one IOL to choose from. There are basic IOLs and “premium” or special IOLs. The special IOLs have advanced features beyond the basic ones and aren’t always covered under your health insurance plan.
Here are some premium IOLs you can choose from:
Aspheric IOLs—the usual basic IOLs are spherical in nature, which is easy to produce but isn’t the exact shape of the lens it replaces. Aspheric lenses more naturally mimic the actual shape of the human lens. This gives better vision in low-light conditions than a regular basic IOL. For people with larger pupils or who have to work in low-light conditions, this is a better lens to select.
Toric IOLs—these are lenses that correct astigmatism, nearsightedness, or far-sightedness. Like soft contact lenses of the same name that have different powers at different parts of the lens, toric IOLs are specially aligned to correct astigmatism. The surgeon marks the cornea so that the IOL can be rotated into place. This takes the place of having to do an extra procedure later to correct astigmatism. If astigmatism persists, LASIK corrective surgery can be done to fix this problem.
Accommodating IOLs—most conventional IOLs correct nearsightedness so you can see far distances. You will still need to wear glasses or contacts in order to see things up close. This is not the case with accommodating IOLs. They allow for clear vision for both near and far vision. There are flexible “legs” on these lenses that allow for movement of the lens when you need to see near objects clearly. You will have a decreased need for reading glasses after cataract surgery.
Multifocal IOLs—these are another type of IOL that corrects presbyopia (the inability to see things up close with increasing age). These have extra magnification for near vision along with the regular far-vision capabilities. It reduces the need for glasses or contact lenses after surgery. These tend do the same thing as accommodating IOLs but work a little bit better. They aren’t as good, however, when it comes to far vision.
Monovision cataract surgery attempts to correct near vision and far vision at the same time. It fixes one eye primarily for nearsightedness and the other eye for farsightedness. This allows one eye to see things at a distance and the other eye to see things up close. You gradually adjust your vision to use one eye for far distance and the other for things like reading and working on the computer.
Are there things you can do to prevent cataracts from occurring in the first place? Remember that it is believed that oxidative stress in the lens contributes to getting cataracts. Oxidative stress happens when there are too many damaging oxygen free radicals in the tissues and too few of the neutralizing antioxidants. Free radicals involve a molecule that is desperate for a hydrogen atom and that will take one from a healthy molecule. Antioxidants will provide that hydrogen atom, sparing healthy molecules.
It is possible that, by eating foods high in antioxidants will slow the progression of cataracts. Foods high in antioxidants will provide ways to get rid of oxygen free radicals, preventing free radical damage to the lens of the eye. It is believed that the free radicals that damage the lenses of the eye come from pollution, exposure to chemicals, smoking, eating an unhealthy diet, and UV radiation.
Foods high in colorful vegetables, fruits, and whole grains seem to decrease the risk of cataracts. Phytochemicals and antioxidants found in vegetables and fruits may decrease the risk of cataracts and include zeaxanthin, lutein, and vitamins A, C, and E. Eating fish high in omega-3 fatty acids has been linked to decreased cataracts or the progression of existing cataracts.
While there are “eye vitamins” and vision-related supplements, it is believed that it is better to get your antioxidants and other vitamins from foods rather that from supplements. If you absolutely can’t get it out of your diet, it’s probably better than nothing to use one of the supplements dedicated to eye health. Ask your eye doctor about which supplements they recommend. Certain vitamins are toxic at high levels so taking more of the vitamin or supplement than recommended is not a good idea.
A diet that can help improve your vision includes consuming 5-9 servings of fruits and vegetables every day. It is preferable to eat fruits and vegetables with a lot of innate color as these are high in antioxidants. You should also eat three servings of whole grains daily and two servings of fish per week. It is a good idea to keep up a healthy weight as obesity is linked to having cataracts. Avoid sugar, processed foods, soft drinks, and fried foods—all linked to obesity and cataracts. A low sodium diet is better than a high sodium diet.
It is also a good idea to keep your eyes from being exposed to UV radiation. Dietary modifications will do nothing if you don’t protect your eyes from the sun. Some things you can do include wearing a wide-brimmed hat or wearing polarized sunglasses that provide 100 percent of the UV protection you need for eye health. UV-protecting contact lenses can also be worn but you should know that it doesn’t protect the entire eye and can damage non-lens parts of the eye.
1. Facts About Cataract– This site is put out by the National Eye Institute and provides a thorough discussion of cataracts for lay people. It talks about the anatomy of the eye, the causes and risk factors for cataracts, the different types of cataracts, and the treatment of cataracts.
2. The American Optometric Association puts out this website, which gives a nice overview of what cataracts are, the types of cataracts, the symptoms you can expect from cataracts, and how they are treated.
3. Cataract surgery– If what you’re interested in are the basics of cataract surgery, this is the website to read. It talks specifically about surgical options for cataract surgery, including laser surgery and traditional options.
4. The American Academy of Ophthalmology produces this site about cataract surgery and how it’s done. It is a good site for individuals who have committed to surgery and who want to know what to expect out of this type of surgery.
5. Age-related cataracts- This is a good website for health professionals and informed lay people that discusses specifically age-related cataracts versus other cataract types. The causes and epidemiology of cataracts are covered along with presentation, diagnosis, and treatment of cataracts.
6. Congenital cataracts– For those who have a newborn who was diagnosed with cataracts, this site is good for an overall review of the topic. Congenital cataracts are unique in that they start at birth so it pays to look at a website specifically on this topic if this applies to you.
7. Traumatic Cataract– If you or someone you know suffered from a traumatic cataract, this is different from an age-related cataract and you need this site to help you understand how this happened and what you can expect with this type of cataract.
8. 5 Tips for Living with Cataracts– When cataracts are affecting your life and you need to learn how to manage life with cataracts, this site can help. Living with cataracts before surgery can be challenging and you will need the help of sites like this one to get through it.
9. This is a great review site on cataracts, including the basics of cataracts, symptoms you can expect, risk factors, causes, and treatment of cataracts. Everything you wanted to know about cataracts is on this site.
10. Tips for Coping with Vision Loss– Living with vision loss from cataracts can be confusing and difficult. This site provides practical information on how to cope with vision loss on a day-to-day basis. These simple tips can make living with cataracts a lot less frightening.