Health

Cataracts

Cataract is the term used to describe any opacification or loss of clarity of the crystalline lens in the human eye.  Cataracts can be present at birth and, although they may develop at any age, are usually common in older age groups.  They vary in degree such that some people don’t notice any difficulty seeing, to people being completely blind with only light perception vision.  Symptoms will vary from seeing halos around lights while driving a car at night, annoying glare outdoors in the daytime, poor night vision, and/or reduced vision for reading or distance vision.  Eye doctors generally measure the severity of cataracts by measuring the deterioration of best-corrected visual acuity.  Contrast sensitivity can also be measured which is a way of quantifying the amount of glare caused by cataracts.

The most common type of cataract in humans is age-related, which is caused by the oxidation of lens proteins in the crystalline lens.  Increased exposure to ultra-violet (UV) light has been shown to contribute to the earlier development of cataract, so wearing glasses that filter UV light is an important environmental modification for those of us who are proactive, spend a significant amount of time outdoors, especially on the beach or water where reflected light adds to the exposure to UV light, and want to do something to prevent deterioration of vision later in life.  Children are particularly susceptible to damaging UV light exposure to both their skin and their eyes, due to the rapid growth rate of their tissues.  Other causes of cataracts, which can occur or can be found at any age, are trauma, infection inside the eye (endophthalmitis), congenital causes (such as rubella), medications (such as the use of steroid medications by mouth, by injection, in the eye, or on the skin), and inflammation in the eye (uveitis – caused by autoimmune disease).

Mild degrees of cataract can sometimes be managed just by having the correct prescription for glasses which may include lenses that filter out (or block) the more glare-producing blue light.  Cataracts are easy for your eye doctor to see in a routine examination using standard extant equipment.   When corrective lenses won’t give you the vision you need to function well, then your eye physician may recommend you have surgery to remove the cataract. Unfortunately, there are no other treatments for cataracts (such as eyedrops) that have been shown to be of any benefit in reversing or stopping the development of cataracts.  There are some products available in foreign countries but none of these have been shown to be effective in a clinical trials.

When it comes to having cataract surgery, generally speaking, it is an elective procedure.  This means you do not have to have surgery on an urgent basis.  It is extremely rare (less than 0.1%) to have a type of inflammation in the eye caused by the cataract itself (called phacolytic or phacomorphic glaucoma) where it is an emergency requiring cataract removal.  If you don’t have this diagnosis, then you don’t need to have surgery until you feel you are ready for it.  The need for cataract surgery is generally quite subjective and very dependent on your perception of how bad your vision is.

In the United States, cataract surgery is generally performed as an outpatient procedure under local anesthesia in consenting adults.  Usually the anesthesia is topical (using eyedrops or anesthetic gel on the ocular surface) without any needles being used around the eyes for injections.  Oral or intravenous sedation may be used depending on the patient’s level of anxiety.  In children and other exceptional circumstances, general anesthesia is used.  The surgery can be completed in as little as ten minutes but may take twice that time or more, if a “special” or so-called “premium” intra-ocular lens (IOL) implant is used in the surgery or if a laser is being used to perform part of the procedure.  Bear in mind, that “premium” has nothing to do with IOL quality (all the lens implant used in the US are of very high quality to pass FDA standards) but refers to the cost of the IOL.  More than 98% of all patients having surgery will need an IOL to correct their vision so it is useful after surgery.

Cataract surgery in the U.S. and in other economically advanced countries around the world is generally performed using Phacoemulsification, a technique that allows for “no-stitch” surgery, which allows for rapid healing and recovery of vision, with little discomfort.  Other techniques requiring larger incisions may be slower to heal, may cause some discomfort, and may take longer to perform due to their requiring stitches.  Phacoemulsification uses a needle-like device with a vibrating tip (vibrating at ultrasonic frequencies) to break the cataract into pieces small enough to be aspirated from the eye through the needle tip.  IOL technology has led to the development of soft lenses which can be folded (or rolled up) into a needle-like cartridge so they can be injected through the small incision into the eye where they then unfold and can be positioned to remain stable in the eye.

IOLs come in many powers, which allow a choice of optical correction for the patient to see well at a certain distance of their choice, providing the rest of the eye is healthy.  Special (“premium”) IOLs are now manufactured to correct astigmatism, increasing the options for better quality vision (better visual acuity) post-operatively.  There are also implants which can provide bifocality with the ability to see far and up close without having to wear reading glasses after surgery.  One type of FDA-approved IOL in the US (the Crystalens) can actually change its focus in the eye depending on whether the patient is trying to see far or up close.

There are trade-offs with each of these IOLs when it comes to the visual result, and it is important to have an open discussion with your physician so he can understand what your expectations are and how you will be using your eyes.  All bifocal IOLs cause a loss of contrast sensitivity, which can translate to seeing glare or halos around lights after the surgery.  These implants may not be good for someone who needs to drive a car at night.  Mono-focal IOLs, which includes spherical lens implants (traditional implants) and the newer toric (astigmatic) lens implants that correct astigmatism, will give very sharp vision at a certain fixed distance agreed upon with your surgeon pre-operatively, but will require the use of glasses to give a clear focus at other distances.  The Crystalens tends to lose its ability to change focus over time and its position in the eye sometimes leads to difficulty seeing well.

Lasers can now be used to assist in making incisions in the eyeball for cataract surgery and can help to emulsify the cataract to make it easier to remove with phacoemulsification equipment, requiring less ultrasound energy which may have benefits for post-operative healing.  This equipment, however, increases costs for cataract surgery, increases the length of the cataract operation, and has yet to show any clear benefits to the patient over conventional phacoemulsification.  As a result, it is not being used by the majority of ophthalmologists performing cataract surgery in economically developed countries.  In less economically developed countries, lasers are not being used.

Cataract surgery is the most successful surgery performed on the human body with a general complication rate of 1%.  No other major organ surgery comes close!  The visual results of the surgery will greatly enhance the quality of life for the overwhelming majority of individuals deciding to have the surgery.  Complications include infection in the eye (endophthalmitis), hemorrhage, glaucoma, and retinal detachment.  All of these complications can be treated successfully, in many cases with a good visual result, and it is extremely rare for cataract surgery to result in blindness.  This very low rate of complications should not discourage you from having surgery if your eye doctor recommends surgery.  If you have any misgivings or unanswered questions after discussions with your ophthalmologist, you should seek a second opinion.

 

 

 

 

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  • Barbara Thornbrough April 1, 2019 at 6:49 pm

    Thanks writing for this very interesting write up on cataract surgery. I was to have surgery 2 weeks ago but then had to reschedule due to the flu. I told the Dr. I could not have it done before the Rolliing Stones concert in Miami. First things first – right? Now I have delayed and Mick is having his surgery. So I am glad I had to cancel as this is very thorough and is of great interest to my complicated eye case. With gratitude,
    Best to Dr. Pat. Best Dr ever!!!! BT

    Reply
    • Patricia Yarberry Allen, M.D. April 7, 2019 at 6:25 pm

      Barbara, we miss you here in the Northeast.
      Come home!
      Dr. Pat

      Reply