What Causes Cataracts?
No, it’s not M&M candy! In this blog post I’ll discuss cataracts and how they are like an M&M, so that hopefully you will learn all you need to know before having an exam with your eye surgeon, an Ophthalmologist.
What are Cataracts?
First, let’s talk about what a cataract is. Many times I’ve heard my patients say that “the cataract has to grow big enough“ or “they told me I have the start of a cataract.“
It makes me realize that the concept of a cataract is not very well known by the general public. This is totally understandable. Cataracts are extremely common –I always say “if you live long enough, you will get a cataract.“
Imagine a plain chocolate M&M candy. The shape and size of a M&M candy is very close to the shape and size of the natural lens of your eye, which sits behind the colored part of your eye (iris). This amazing structure is crystal clear and very flexible when we are born. It undergoes several stages throughout our lives.
Lens stage 1. Development and Growth: When you are just a tiny fetus inside your mother, the lens of your eyes develops in the first trimester. It first looks like a ball and then flattens out later. Newborn babies have very poor vision just because their brains aren’t developed yet, but the eyeballs typically are somewhat farsighted initially. A newborn baby‘s vision typically gets better very quickly as the visual part of their brain develops. From birth until about age 18 the refractive error changes and stabilizes. This means that if we are going to be nearsighted, it typically starts between age 7 and 12, although more nearsighted people tend to develop myopia (nearsightedness) at a younger age.
Lens Stage 2. Stable Vision Age 18-45: This is the stage that your refractive error (classes prescription) stays relatively stable. Most people think that their eyes may continue to change into their 20s and 30s, but this is rare. When we measure your prescription, it may change slightly up or down but generally stays about the same in our young adult years.
Lens stage 3: Presbyopia: Presbyopia is the condition that makes people need reading glasses, bifocals, or need to take off their glasses to see things up close. The reason is that the lens of our eye is very flexible in our 20s and 30s, but decreases in flexibility in our 40s to the point where the lens cannot add the focusing power needed to focus on near objects. This additional focusing power must be added with a bifocal, multifocal contact lenses, monovision surgery (where one eye is focused up close and one eye is focused far away) or lens replacement surgery with a multifocal intraocular lens (RLE). The loss of flexibility is complete in our early 50s. It does not continue to get worse, but near vision is very challenging for someone over 50 years old who has perfect distance vision.
Lens stage 4. Cataract Development: There’s no particular time in which one doesn’t have a cataract and then has a cataract the next day. The vast majority of cataracts occur with the very slight change in the proteins that make up the natural lens of our eyes. This change affects the clarity and ability of the natural lens to transmit light. It becomes less clear and the color changes to a slight greenish yellow. It reminds me of a plant sitting in water on your windowsill. The water is clear at first, then becomes slightly yellow green and then darker to the point where you can’t see through it. This analogy is appropriate for a cataract, although the cataract typically develops over 10 or 20 years. At some point in that transition, one must decide to have cataract surgery in order to see well enough to continue basic life tasks. This is called impaired activities of daily living or impaired ADLs. When your ADLs are impaired, typically insurance will help pay for some of the expenses of cataract surgery.
In summary, a cataract is defined as any clouding or opacification of the natural lens of our eyes.
What Causes Cataracts?
There are quite a few known causes of cataracts, but about 95% of all cataracts are age related. They used to be called “senile cataract”, but this term has fallen out of favor.
Known Causes of Cataracts:
- Age Related: although this is the most common cause of cataracts, and as I stated above “if you live long enough you will get a cataract,“ this may not always be the case. Hopefully someday we will figure out ways to slow the progress of a cataract. There are some things we already believe to be associated with the acceleration of the cataract development. Not surprisingly, they are generally associated with poor health habits and conditions. Heavy smokers can get cataracts at a very young age, even in their 30s, although this isn’t terribly common. They generally develop cataracts in their 50s and 60s instead of their 60s and 70s. Diabetes, obesity, and being highly nearsighted are also risk factors for developing cataracts.
- Chronic Steroid Use: topical use such as steroids in eyedrops or a cream used around the skin of the eyes can cause cataracts. I have even seen a couple patients who developed a cataract after chronic use of Flonase, a steroid spray for nasal congestion. These cataracts have a typical appearance and are called a posterior subcapsular cataract. Often these can happen in younger people, even in their 30s and 40s, and can progress over a period of a month or more. However they can also be stable for many years and not affect the vision, if they are slightly off-center of the visual axis.
- Radiation: radiation can cause cataracts to develop very quickly as in a nuclear radiation leak or exposure. I remember a colleague who was a radiologist who placed a lot of cardiac stents and developed cataracts younger than he might have had he chosen a non-radiation type of career.
- Trauma: blunt or penetrating trauma can cause cataracts at any age and can be difficult to treat because the surrounding structures of the eye may also be damaged.
- Congenital or Pediatric: sometimes babies are born with cataracts of varying severity that often need to be removed quickly to prevent Amblyopia-a condition where the vision center of the brain doesn’t develop properly due to lack of exposure. It can lead to permanent impairment of vision.
- Sunlight: lifetime ultraviolet radiation can accelerate the development of cataracts.
- Certain metabolic disorders can cause cataracts
What Are the Symptoms of Cataracts?
Symptoms of cataracts most commonly begin as increased glare at night and difficulty driving in low light. It can progress to difficulty reading road signs or anything else. Cataracts cause light to scatter instead of coming to a clean crips focus on the retina (back of the eye). Color vision also becomes increasingly impaired. After cataract surgery, most patients will see the cool colors (blues and greens) more intensely. I had a patient who was an interior designer who said all her curtains would have to be changed after her cataract surgery because the color was all wrong!
Do Cataracts Cause Dizziness or Headaches?
Not usually. If dizziness or headaches are problematic, they should be investigated once a complete eye exam is done.
Do Cataracts Cause Double Vision?
Double vision due to cataracts is a less common symptom but possible. The double vision from cataracts typically comes from just one eye. To determine if the double vision is coming from one or both eyes, cover one eye and see if the double vision disappears. A complete exam is required for someone with double vision. The causes of double vision are many and can be a symptom of a serious neurologic condition.
Can Lasers Remove Cataracts?
As of the writing of this blog post, cataracts cannot be removed with a laser, but a femtosecond laser is an amazing and relatively recently approved device to make the incisions and break up the cataract in place. The technique is called “FLAPS” (femtosecond laser assisted cataract surgery) or femto-phaco, where a femtosecond laser is used to make the small incisions and break up the lens material. The cataract lens material is then removed more easily. An artificial lens is placed in the eye to focus without glasses.
How are Cataracts Removed?
Imagine that same M&M plain chocolate candy that I described above. It sits behind the iris (the colored part of your eye). Many eyedrops are used to dilate your pupils, which moves the iris out of the way. If the surgeon uses a laser to assist in cataract surgery, the laser interface is placed on the eye. The laser itself is utterly painless and takes anywhere from 45 to 60 seconds to complete the incisions, “capsulorhexis,” and cut the lens material into quadrants. The capsulorhexis is the term for cutting a perfect 5mm circle in the center of the capsule (the shell of the M&M). Phacofragmentation is the term for breaking up the lens material (the chocolate of the M&M). If using a laser to assist in cataract surgery, the incisions are made last. A “main” incision is usually 2.5-3.5mm wide, but can be programmed to any size or shape. A side port called a paracentesis is also created. It’s used to insert a second instrument in the eye and is 1mm wide. After the laser does its part, the surgeon removes the lens material, and places an intraocular lens (IOL) in the eye. The IOL is rolled in a tiny delivery funnel and opens inside the eye where it stays the rest of your life. It doesn’t wear out or need to be replaced like an artificial joint might.
Over 4 million cataract surgeries are performed in the United States each year, which makes it the most common surgical procedure paid in part by Medicare. It’s safe and always advancing; and in the hands of an experienced surgeon is amazingly quick, painless, and an easy 6-10 minute procedure. When you need it, it can keep you seeing clearly until you’re 115 years old. May you enjoy every day of clear uncorrected vision for as long as you live!