Cataract Eye Surgery
Cataract
What Is a Cataract?
A cataract is a dense, cloudy area that forms in the lens of the eye. A cataract begins when proteins in the eye form clumps that prevent the lens from sending clear images to the retina. The retina works by converting the light that comes through the lens into signals. It sends the signals to the optic nerve, which carries them to the brain.
It develops slowly and eventually interferes with your vision. You might end up with cataracts in both eyes, but they usually don’t form at the same time. Cataracts are common in older people.
SYMPTOMS OF CATARACTS
Common symptoms of cataracts include :
Blurry vision Trouble seeing at night Seeing colors as faded Increased sensitivity to glare Halos surrounding lights Double vision in the affected eye. Aneed for frequent changes in prescription glasses WHAT CAUSES CATARACTS ?
There are several underlying causes of cataracts. These include:
An overproduction of oxidants, which are oxygen molecules that have been chemically altered due to normal daily life Smoking Ultraviolet radiation The long-term use of steroids and other medications Certain diseases, such as diabetes Trauma Radiation therapy TYPES OF CATARACTS
There are different types of cataracts. They’re classified based on where and how they develop in your eye.
Nuclear cataracts
Nuclear cataracts form in the middle of the lens and cause the nucleus, or the center, to become yellow or brown.
Cortical cataracts
Cortical cataracts are wedge-shaped and form around the edges of the nucleus.
Posterior capsular
Posterior capsular cataracts form faster than the other two types and affect the back of the lens.
Congenital cataracts
Congenital cataracts, which are present at birth or form during a baby’s first year, are less common than age-related cataracts.
Secondary cataracts
Secondary cataracts are caused by disease or medications. Diseases that are linked with the development of cataracts include glaucoma and diabetes.
Traumatic cataracts
Radiation cataracts can form after a person undergoes radiation treatment for cancer.
Radiation cataracts
Radiation cataracts can form after a person undergoes radiation treatment for cancer.
RISK FACTORS OF CATARACTS
Risk factors associated with cataracts include :
OLDER AGE
HEAVY ALCOHOL USE
SMOKING
OBESITY
HIGH BLOOD PRESSURE
PREVIOUS EYE INJURIES
A FAMILY HISTORY OF CATARACTS
TOO MUCH SUN EXPOSURE
DIABETES
EXPOSURE TO RADIATION
DIAGNOSING CATARACTS
Your doctor will perform a comprehensive eye exam to check for cataracts and to assess your vision. This will include an eye chart test to check your vision at different distances and tonometry to measure your eye pressure.
The most common tonometry test uses a painless puff of air to flatten your cornea and test your eye pressure. Your doctor will also put drops in your eyes to make your pupils bigger. This makes it easier to check the optic nerve and retina at the back of your eye for damage.
Other tests your doctor might perform include checking your sensitivity to glare and your perception of colors.
TREATMENT
Treatment
Cataract cannot be corrected with glasses or medication. Surgery is the definitive treatment. Various surgical options are available depending on the severity of cataract and patient’s lifestyle.
In cataract surgery the cloudy lens is removed from the patients lens bag and replaced with an artificial one. At RNH Hospital, we perform cataract surgery by taking a microunioun (2mm) and phacoemulsifying the nucleus .it is an incredibly delicate procedure requiring lots of skill.Modern day cataract surgery is evolving from a visual restorative to a refractive procedure.
There are numerous types of IOL (Intraocular lens) option that we use to replace the original one.
Intraocular lenses (IOLs) are medical devices that are implanted inside the eye to replace the eye’s natural lens when it is removed during cataract surgery. IOLs also are used for a type of vision correction surgery called refractive lens exchange.
Before the use of intraocular lenses, if you had cataracts removed, you had to wear very thick eyeglasses or special contact lenses in order to see clearly after cataract surgery, since no device was implanted in the eye to replace the focusing power of the natural lens.
Today there is a wide variety of premium IOLs to choose from. The best intraocular lens for you depends on many factors, including your lifestyle and your specific visual needs.
The following is an overview of premium IOLs currently used. These are considered “premium” intraocular lenses because they have advanced features beyond those found in basic single vision IOLs.
During your preoperative exam and consultation, your cataract surgeon can help you choose the best IOL for your needs.
PREMIUM MONOFOCAL IOL (ASPHERIC IOLS)
Traditional intraocular lenses have a spherical optical design, meaning the front surface is uniformly curved from the center of the lens to its periphery. Though a spherical IOL is relatively easy to manufacture, this design does not mimic the shape of the natural lens inside the eye, which varies in curvature from center to periphery. In other words, the eye’s natural lens is aspheric (“not spherical”).
Why is this important?
A spherical intraocular lens can induce minor optical imperfections called higher-order aberrations (HOAs), which can affect quality of vision, particularly in low-light conditions such as driving at night.
Premium aspheric IOLs, on the other hand, match more closely the shape and optical quality of the eye’s natural lens, and thereby can provide sharper vision — especially in low light conditions and for people with large pupils.
TORIC IOLS
Toric IOLs are premium intraocular lenses that correct astigmatism as well as nearsightedness or farsightedness.
Like toric soft contact lenses, toric IOLs can correct astigmatism because they have different powers in different meridians of the lens. They also have alignment markings on the peripheral part of the lens that enable the surgeon to adjust the orientation of the IOL inside the eye for optimal astigmatism correction.
Just prior to cataract surgery, the surgeon places temporary markings on the patient’s cornea that identify the location of the most curved meridian of the front of the eye. Then, when the toric IOL is implanted during the cataract procedure, the surgeon rotates the IOL so the markings on the IOL are aligned with the markings on the cornea to insure proper astigmatism correction.
Prior to the development of toric IOLs, cataract surgeons had to perform a procedure call limbal relaxing incisions (LRI) to correct astigmatism during or after cataract surgery.
In LRI, small incisions are made at opposite ends of the cornea, very near the junction between the cornea and the surrounding white sclera. When these incisions heal, the cornea becomes more spherical in shape, reducing or eliminating astigmatism.
In some cases — even when a toric IOL is used — limbal relaxing incisions may be needed after cataract surgery to fully correct astigmatism. But typically in such cases, the amount of astigmatism remaining after implantation of a toric IOL is far less, making a better LRI outcome more likely.
LASIK and PRK also can be performed after cataract surgery to correct residual astigmatism, but toric IOLs decrease the likelihood of needing these additional surgical procedures.
MULTIFOCAL IOLS
Multifocal IOLs are another category of presbyopia-correcting IOLs that can decrease your need for reading glasses or computer glasses after cataract surgery.
The advent of multifocal intraocular lenses (MFIOLs) allows greater spectacle independence and increased quality of life postoperatively. Since the inception in 1980s, MFIOLs have undergone various technical advancements including trifocal and extended depth of vision implants more recently. A thorough preoperative workup including the patients’ visual needs and inherent ocular anatomy allows us to achieve superior outcomes.
Patients’ requirements have greatly increased in recent years and even perfect distance vision correction is not enough to fully satisfy a cataract surgery patient.
This is particularly notable in a myopic patient who had no problem with his intermediate and near vision before his cataract and his corrective surgery. Monocular vision and/or depth of field increase by spherical aberrations management are not always sufficient to reach the goal of less spectacle dependence.
Such patients will be preferentially attracted by multifocality if they accept the induced visual compromise (halos and reduced contrast sensitivity at low luminance).
WHICH PATIENTS ARE SUITABLE FOR THIS SURGERY?The most suitable patient is the one who strongly desires not to wear glasses after having eliminated medical contra-indications and exposed side eff ects especially halos.
Patients with significant night activity should be avoided as halos at night may disturb patients especially when driving.
These halos disappear for 20% of patients during the first month and for 40% of patients during the first year presumably by a Neuro-adaptation phenomenon.
They persist to varying degrees for the remaining 40% without significant reduction in activities.
WHICH PREOPERATIVE ASSESSMENT?An orthoptic assessment will be done to eliminate any microtropia. Analysis of the cornea must be scrupulous and any disease of the tear film must be treated beforehand because meibomian gland dysfunction can greatly disturb patients postoperatively.
New apodized diffractive IOLs being pupil-dependent, photopic (Scheimpflug data) and mesopic (Colvard Pupillometer) measurement of the pupil will avoid narrow photopic or over dilated scotopic pupils.
Limits of 2mm in photopic and 5 mm in scotopic will avoid any pupillary refractive disorder postoperatively.
Astigmatism management is of paramount importance for obtaining ideal postoperative results with MFIOLs. A postoperative astigmatic error exceeding three-quarters of a diopter results in significant decline in visual quality.
A residual astigmatism lower than 0.50D does not seem to impair visual acuity, but we systematically treat astigmatism with toric lens if possible with the goal of no residual astigmatism.
Corneal limbal incisions could be performing to treat lower astigmatism.
Pathological capsular bags or capsular bags at risk because of uncontrolled healing should be avoided in order to prevent any decentration of these IOLs.
Finally a macular OCT analysis is performed when there is a doubt at fund us examination in order to eliminate an incipient macular traction syndrome or Epiretinal Membrane (ERM)
TYPES OF MULTIFOCAL INTRAOCULAR LENSES
Accommodation, a property of the young crystalline lens allows focus for both distance and near vision. This is generally lost as the person ages or following cataract surgery wherein the natural lens is replaced with a monofocal intraocular lens. Presbyopia-correcting intraocular lenses (IOLs) including MFIOLs provide spectacle independence for both near and distance vision.
Three general optic principles have been applied to provide multifocality in the present day IOLs: multizonal refractive, diffractive, and extended range of vision (EROV) designs.
Refractive IOLs
Refractive IOLs use concentric or annular ring-shaped zones of varying dioptric powers. With changes in the pupil diameter in response to illumination and accommodation, the number of zones in use vary redistributing the proportion of light directed for distance and near. Hence, the image quality and energy balance is pupil dependent
Diffractive IOLs
Diffractive IOLs are engineered with microscopic steps of a specific phase delay, usually half a wavelength: Huygens–Fresnel principle. Light encountering these steps is directed equally between distant and near focal points for all pupil diameters. A portion of the light energy of around 18% is directed into higher diffraction orders, with the remaining distributed equally for distance and near, i.e., 41% each.
Extended depth of focus (EDOF) IOLs
EROV or extended depth of focus (EDOF) IOLs: The Symfony IOL (Tecnis, Abbott Medical Optics Inc., Johnson and Johnson vision) combines a unique diffractive pattern with achromatic technology and a proprietary echelette design resulting in an elongated depth of focus.
Trifocal IOLs with three focal points have been introduced to overcome the limitations associated with prior bifocal models.The additional intermediate focus provides superior quality of vision for intermediate activities.
WHICH SURGICAL TECHNIQUE?
It seems to us that sub 2mm micro incision (CMICS or BMICS) should be the rule in order to prevent any astigmatism induced by the incision and the risk to increase high order aberrations.
If topical anesthesia is becoming increasingly popular, we have chosen since 2012 to systematically perform sub-Tenon anesthesia to avoid any discomfort during the procedure.
The second eye is operated on 2 to 5 days after the first one to eliminate any trouble due to an eventual anisometropia.
Surgery to remove a cataract is generally very safe and has a high success rate. Most people can go home the same day as their surgery.
OUTLOOK OF A CATARACT
Cataracts can interfere with daily activities and lead to blindness when left untreated. Although some stop growing, they don’t get smaller on their own. The surgical removal of cataracts is a very common procedure and is highly effective roughly 90 percent of the time, according to the National Eye Institute.
PREVENTION OF CATARACTS
To reduce your risk of developing cataracts :
Protect your eyes from UVB rays by wearing sunglasses outside Have regular eye exams Stop smoking Eat fruits and vegetables that contain antioxidants Double vision in the affected eye. Keep diabetes and other medical conditions in check 7 SYMPTOMS OF CATARACTS
Could you have cataracts?
You use the lens of your eye every day, for everything from reading to driving to bird watching. With age, the proteins inside your lens can clump together turning the lens from clear to cloudy. Certain behaviors can put you at a higher risk for getting a cataract. These include:
- Too much time in the sun without eye protection
- Smoking
- High blood sugar
- Using steroid medications
- Exposure to radiation
If you have any of the following symptoms, talk to your eye doctor soon.
Cloudy days
Cataracts start small and initially may have little effect on your vision. Things might seem a little blurry — like looking at an impressionist painting. This effect usually increases over time. The world will seem cloudy, blurry, or dim.
There are three main types of cataracts, affecting different parts of the lens:
- Posterior subcapsular cataracts
- Nuclear cataracts in the center of the lens
- Cortical cataracts on the side of the lens, which appear as small streaks
Those with nuclear cataracts may briefly see their vision improve. This sensation is sometimes called “second sight.”
No more wild nights
As cataracts become more advanced, they begin to darken with a yellow or brown tinge.
This begins to affect night vision and makes certain nighttime activities, such as driving, more difficult.
If you suspect you have cataracts, be very careful at night and don’t drive when your vision is compromised.
The glare of bright lights
Light sensitivity is a common symptom of cataracts. The glare of bright lights can be painful, especially to those with posterior subcapsular cataracts. These types of cataracts start at the back of the lens, blocking the path of light and often interfere with your reading vision.
Halos everywhere?
The clouding of the lens can result in diffraction of light entering your eye. This can cause a halo to appear around light sources. Rings around every light, sometimes in a variety of colors, can make driving very difficult. This is another reason why driving at night, especially when there are streetlights and headlights, can be dangerous if you have a cataract.
New glasses again
If you find yourself frequently needing stronger glasses or contacts, you may have cataracts. Simply buying a strong pair of reading glasses from the drugstore isn’t going to fix the problem. See an eye doctor if your eyesight is changing rapidly. You may have cataracts or another eye condition that will benefit with prompt treatment.
Living in a yellow submarine
As cataracts progress, the clumps of protein clouding your lens may turn yellow or brownish. This results in all the light coming into your eye having a yellow tint. It’s almost as though you are wearing “blue-blocker” sunglasses, as advertised on TV, which block blue and violet light. This changes how you see color and reduces your ability to tell the difference between colors.
After corrective surgery for cataracts, you may be surprised to see the world with all of its colors again!
Double trouble
Diffraction from the lens clouding in a cataract can actually lead you to see two or more images of a single object. Many things can cause double vision, also called diplopia, including :
- brain tumor
- corneal swelling
- multiple sclerosis
- stroke, cataracts
Binocular double vision, which causes two images to be visible only if both eyes are open, can be a sign of serious health concerns, including :
- brain injury
- uncontrolled diabetes or hypertension
- Graves’ disease
- myasthenia gravis
SEE YOUR DOCTOR
Cataracts can cause significant changes in vision. Cataracts occur not only in older adults, but in younger people, too. Injury, certain medications, and genetic conditions can result in cataracts, even in the very young.
It should be noted that not all vision changes are the result of cataract. Several of the above symptoms can be signs of very serious and life-threatening conditions. See an eye doctor to discuss your vision changes and any other symptoms you may be experiencing.