complication of cataract

With the exception of a secondary cataract, which is common and easily treatable, more than 97 percent of cataract procedures occur without complication.

During, Immediately After, and Within 24 Hours of Surgery

Bleeding. Bleeding inside the eye during cataract surgery is extremely rare, because the incision is placed on the edge of the cornea, which contains no blood vessels. When it does occur, it is most likely to occur on the surface of the eye. In this case, the surgeon will usually cauterize the bleeding area, and the bleeding stops.

Bruising or black eye. If your doctor used an injection to numb your eye, it is possible that you may experience some bruising around your eye. This is temporary and will go away on its own.

Incision leak. Sometimes a small leak in the incision in the cornea can occur. Such a leak increases the chances of infection, and your doctor may apply a contact lens or pressure bandage over your eye to help decrease the chances of infection. In some cases, the incision must be closed with a stitch.

Infection or endophthalmitis. Developing an infection after cataract surgery is extremely rare, occurring only once in several thousand surgeries.(1) Most cataract surgeons administer antibiotic drops before, during, and after surgery to further minimize the risk of infection. Endophthalmitis, an inflammation of the eye triggered by infection, is also very rare and more common in people with conditions that compromise their immune systems, such as diabetes.

Inflammation. Swelling inside the eye that is unrelated to infection is usually minor and can be easily treated with anti-inflammatory drops after surgery.

Glaucoma. An extremely small number of cataract surgery patients develop secondary glaucoma after cataract surgery. Secondary glaucoma is usually temporary and can develop when inflammation or bleeding occurs during the surgery. In most cases, glaucoma medications can be used to help control the increased intraocular pressure, but sometimes, laser or other surgery is required.

Pronounced astigmatism. Sometimes swelling of the cornea or tight stitches (if stitches are used) can distort the shape of the cornea, causing astigmatism. Swelling will reduce during healing, and the astigmatism will generally go away on its own. Or if stitches were used, once they are removed, the cornea will usually relax back to its natural shape.

Retinal detachment. If you are extremely nearsighted, you may be more prone to retinal detachment during cataract or any other eye surgery. Symptoms of retinal detachment include flashing lights, new floaters, gradual shading of vision as though a curtain were being drawn, and quick detachment of your sharp, central vision. If you experience any of these symptoms following cataract surgery, call your doctor immediately.

Tearing of the posterior capsule. During cataract surgery, the natural lens is removed from the posterior capsule and replaced with an artificial IOL. During this process sometimes this capsule can tear. When this happens, the physician will perform a vitrectomy, a procedure to remove and repair the vitreous body that has leaked into the capsular bag, and seal it off.

One Week to One Month After

Decentered intraocular lens. Rarely, the IOL placed in the eye can become displaced. Symptoms of a decentered IOL can include blurred vision, glare, double vision, or fluctuating vision (when the eye sees the edge of the IOL, causing focused and unfocused images). This is sometimes due to torn zonules during surgery or through an accident involving the eye. When an IOL becomes displaced, your doctor will either reposition the lens or remove and replace it with another.

Two to Four Months After

Cystoid macular edema. For as much as three months after cataract surgery, or as early as a few weeks, the tissues of the macula may swell. If this happens, your central vision will be blurry, and your doctor will most likely give you a non-steroidal anti-inflammatory drug.

Secondary cataract. This is by far the most common complication of cataract surgery, occurring after about 30 percent of surgeries.(1) When you develop a secondary cataract, or posterior capsule opacification, cells have grown under the lens and the posterior capsule holding the IOL has become cloudy, blurring your vision. Your doctor will then perform a YAG (yttrium-aluminum-garnet) laser capsulotomy, using the laser to create a small hole in the membrane to allow light through. This is a painless outpatient procedure that your doctor will perform quickly in office.

Types of Sugery : -Conventional extracapsular surgery
-Pharcoemulsification

Source :http://www.cataractsurgery.com/life-after-cataracts/possible-complications.asp

Epidemiology of Cataract

Worldwide

• Cataract is the leading cause of blindness worlwide
• in 1998, an estimated 20 million people were blind due to cataract
• globally, at least 100 million eyes have visual acuity <6/60>
• annually, at least 25 million eyes develop visual acuity <6/60>

Australia

• the blue mountain study 1997
  
  • 3654 people
    
  • age ranges from 49 to 93 years
    
  • moderate or advanced nuclear opacities were present in 53.3% of women and 49.7% of men
    
  • moderate cortical cataract was present in 25.9% of women and 21.1% of men
  • posterior subcapsular cataract was present in 6.2% of women and 6.5% of men
    

Malaysia

• Diabetes
  
  • 2006 – 10.3% of Malaysian population
    
  • Orang asli 0.3%
    
• National Eye survey 1996
  
  • 18,027 people
  • age ranges from 1 month to 96 years
    
  • mean age 26 years old
    
  • Cataract is the leading cause of blindness, with 39% of blindness and 36% of low vision were due to cataract
    
  • Prevalence of cataract in Malaysia 2.58%
    
    • Women 2.69%
      
    • Men 2.46%
      
  • An exponential increase of cataract after 40 years of age
    
  • The age group with the highest prevalence of cataract was the 70 years and above age group with a prevalence of 54.55%.
    
  • Based on races
    
    • Indian 3.63%
      
    • Other indigenous group 2.79%
      
    • Chinese 2.69%
      
    • Malay 2.29%
      
  • Urban areas had lower prevalence (2.48%) compared to rural areas (2.66%)
    
  • States
    
    • Melaka 5.31%
      
    • Kuala Lumpur 3.37%
      
    • Sabah 3.32%
      

Reference:

1. http://books.google.com/books?id=S28jeel2VfUC&pg=PA130&lpg=PA130&dq=incidence+of+diabetes+in+orang+asli&source=bl&ots=HUqB4iP6P_&sig=tqQKDIf4I8g-W8k-L_ptBDeU8xI&hl=en&ei=JEifStbsKpbU7AOe6OjrCw&sa=X&oi=book_result&ct=result&resnum=4#v=onepage&q=&f=false
   
2. http://www.moh.gov.my/opencms/export/sites/default/moh/download/BI_edisi4pg_2.pdf
   
3. http://www.uniteforsight.org/eye_stats.php
4. http://www.acrm.org.my/ned/documents/NationalEyeSurvey_BJO2002.pdf
5. http://www.ncbi.nlm.nih.gov/pubmed/9111249
   

How to diagnose cataract????

It starts with blurred or cloudy vision. Then suddenly images aren't as sharp, colors aren't as bright and night driving is more difficult. Cataracts generally are associated with aging. Younger people, however, can have them too. Identifying the problem requires an ophthalmologist to administer a variety of tests before a diagnosis of cataracts can be made.

Things you will need:-

1. Medical history

2. Eye examination

3. Visual acuity test

4. Opthalmoscopy

5. Tonometry test

6. Glare test

7. Contrast sensitivity test

1. Medical history

· General health issues/related problems that may affect the diagnosis and prognosis of patient’s cataract and suitability for surgery.

· Medications taken by the patient is recorded. This may affect the surgical decisions/procedures.

· Allergies to antibiotics and anesthetics should be recorded.

2. Eye examination

· To determine the nature and severity of cataract.

· Overall eye health will also be assessed to discover any problems that may limit good vision following surgery/other treatment procedure.

· Measure refractive error with retinoscopy – using retinoscopy to shine light into the patient’s eye and observes the reflection off the patient’s retina.

3. Visual acuity test

· To determine the smallest letters a person can read on standardized chart/card (Snellen eye chart) held 14-20 ft away.

· Glasses and contact lens will be removed.

· Stand/ sit 20 ft from the eye chart.

· One eye is covered while the patient reads out loud the smallest letters he can see.

· Repeat with the other eye, if necessary the test is repeated with your glasses/contact lens on.

· The result is expressed as fraction. Top no. is the distance from the chart (usually 20 ft) and the bottom no. is the smallest letters that the patient can read, e.g. 20/40.

TEST FOR PRESBYOPIA

· Eyes are position at a close reading distance of about 14 ft from the test chart.

· Glasses are not removed.

· The patient is asked to read down the chart, line by line until the line that you cannot read comfortably and clearly.

4. Opthalmoscopy

· To examine the inside and back of the eye with opthalmoscope.

· Pupil is usually dilated with eye drops so the doctor has a larger ‘window’ to look through.

· Look for abnormalities in retina.

5. tonometry test

· To measure the intraocular pressure (IOP) with tonometer.

· Two types:-

a) Applanation tonometry – uses pressure sensitive tip that placed against the surface of eye, > accurate

Air puff tonometry – directs a brief puff of air onto the eye

6. Glare test

· Cataract patients often complain that their vision is slight reduced in brilliant sunlight and night time driving, this is due to increase light scatter within the eyes.

· Glare test + device the measures the effect of stimulated glare on vision function.

· To quantify the effect of glare on the person’s vision.

· Is a benchmark for testing after cataract surgery to see if situation is improved/not

7. Contrast sensitivity test

· To measure ability of eyes to distinguish images under varying degrees of lighting

· Person with low contrast sensitivity may do well in standard vision test and have difficulties in seeing traffic lights/cars at night, spots on clothes and facial gestures OR they may need great deal of light to read and experiences tired eyes while watching tv.

· Repeated after surgery to document the degree of improvement that has been achieved.

Treatment of Cataracts

Surgery

The standard cataract surgical procedure is typically performed in either a hospital or in an ambulatory surgery center. The most common form of cataract surgery today is a process calledphacoemulsification. With the use of an operating microscope, your surgeon will make a very small incision in the surface of the eye in or near the cornea. A thin ultrasound probe is inserted into the eye that uses ultrasonic vibrations to dissolve (phacoemulsify) the clouded lens. These tiny fragmented pieces are then suctioned out through the same ultrasound probe. Once the cataract is removed, an artificial lens is placed into the same thin capsular bag that the cataract occupied. Thisintraocular lens is essential to help your eye focus after surgery.
There are three basic techniques for cataract surgery:

• Phacoemulsification: This is the most common form of cataract removal as explained above. In this most modern method, cataract surgery can usually be performed in less than 30 minutes and usually requires only minimal sedation and numbing drops, no stitches to close the wound, and no eye patch after surgery.

• Extracapsular cataract surgery: This procedure is used mainly for very advanced cataracts where the lens is too dense to dissolve into fragments (phacoemulsify) or in facilities that do not have phacoemulsification technology. This technique requires a larger incision so that the cataract can be removed in one piece without being fragmented inside the eye. An artificial lens is placed in the same capsular bag as with the phacoemulsification technique. This surgical technique requires a various number of sutures to close the larger wound, and visual recovery is often slower. Extracapsular cataract extraction usually requires an injection of numbing medication around the eye and an eye patch after surgery.

Intracapsular cataract surgery: This surgical technique requires an even larger wound than extracapsular surgery, and the surgeon removes the entire lens and the surrounding capsule together. This technique requires the intraocular lens to be placed in a different location, in front of the iris. This method is rarely used today but can be still be useful in cases of significant trauma.

Small Incision Cataract Surgery

In a newer surgical method, called small-incision (no-stitch) cataract surgery, the nucleus is broken up (emulsified) by an ultrasound probe. No-stitch surgery requires only a single, 1/8-inch incision. A small incision means faster healing. Redness and inflammation of the eye disappear in two to three weeks with small-incision surgery, vs. six to eight weeks with extracapsular extraction. A special advantage of small-incision surgery is that it is less likely to cause astigmatism. This is blurred vision that results when tension on the stitches distorts the cornea. Small-incision surgery involves an incision not on the cornea, but on the less sensitive sclera (the white of the eye).
Because of its advantages, many eye surgeons have adopted the no-stitch technique. Others feel strongly that extracapsular surgery is just as good. But after the eye heals completely, there is generally little difference between the results from extracapsular and small-incision surgery. A patient may not be a candidate for the no-stitch method, in that advanced cataracts tend to be too hard to emulsify easily. In such cases, extracapsular surgery may be the better choice.
In the past, people who underwent cataract surgery had to wear thick "Coke bottle" eyeglasses. Now, immediately after the removal of the cataract, the surgeon implants a plastic lens directly into the space left by the removal of the clouded lens. This intraocular implant helps the cornea focus light onto the retina to give a clear image.
There are many different implants on the market and they fall into two general categories, based on their location in the eye:
Posterior chamber implants, the more popular type, are placed behind the iris, occupying the exact position of the original lens. There are now smaller oval and foldable lenses that can be used with small-incision surgery.
Anterior chamber implants are inserted into the fluid-filled space between the iris and the cornea.
Some experts estimate that about 88 of every 100 persons receiving IOLs (intraocular lenses) will achieve 20/40 vision or better. (An individual with 20/40 vision can read letters on an eye chart from 20 feet away. While a person with normal 20/20 vision can read the chart from 40 feet away, 20/40 vision is good enough to get a driver's license in most states.) Among those who do not have other eye diseases, about 94 of 100 will achieve 20/40 vision.
What are the different types of intraocular lenses implanted after cataract surgery?

• As the natural lens plays a vital role in focusing light for clear vision, artificial-lens implantation at the time of cataract surgery is necessary to yield the best visual results. Because the implant is placed in or near the original position of the removed natural lens, vision can be restored, andperipheral vision, depth perception, and image size should not be affected. Artificial lenses are intended to remain permanently in place, require no maintenance or handling, and are neither felt by the patient nor noticed by others.

There are a variety of intraocular lens styles available for implantation, including monofocal, toric, and multifocal intraocular lenses.

• 1. Monofocal lens: These lenses are the most commonly implanted lenses today. They have equal power in all regions of the lens and can provide high-quality vision at a single focal point (usually at distance). They usually require only a light pair of spectacles for optimal distance vision correction. However, monofocal lenses do not correct astigmatism, an irregular oblong corneal shape that can distort vision at all distances, and require corrective lenses for all near tasks, such as reading or writing.

2. Toric lens: Toric lenses have more power in one specific region in the lens (similar to spectacles with astigmatism correction in them) to correct astigmatism, which can further improve unaided distance vision for many individuals. Due to the difference in lens power in different areas, the correction of astigmatism with a toric lens requires that the lens be positioned in a very specific configuration. While toric lenses can improve distance vision and astigmatism, they still require corrective lenses for all near tasks, such as reading or writing.

3. Multifocal lens: Multifocal intraocular lenses have a variety of regions with different power within the lens that allows individuals to see at a variety of distances, including distance, intermediate, and near. While promising, multifocal lenses are not for everyone. They can cause significantly more glare than monofocal or toric lenses. Further, multifocal lenses cannot correct astigmatism, and some patients require additional surgery such as LASIK to correct astigmatism and maximize their unaided vision.

Prevention of cataract

Regular eye exams remain the key to early detection. If you're over age 65, schedule eye exams at least every other year. Although most cataracts occur with age and can't be avoided altogether, you can take steps to help slow or possibly prevent the development of cataracts:

Don't smoke. Smoking produces free radicals, increasing your risk of cataracts.

How free radicals increases your risk of cataracts?
Oxygen, an element indispensable for life can, under certain situations, have severely deleterious effects on the human body. Most of the potentially harmful effects of oxygen are due to the formation and activity of a number of chemical compounds, known as reactive oxygen species, which have a tendency to donate oxygen to other substances. Many such reactive species are free radicals and have a surplus of one or more free-floating electrons rather than having matched pairs and are, therefore, unstable and highly reactive. Types of free radicals include the hydroxyl radical (OH.), the superoxide radical (O.2), the nitric oxide radical (NO.) and the lipid peroxyl radical (LOO.).

Production of free radicals in the human body

Free radicals and other reactive oxygen species are derived either from normal essential metabolic processes in the human body or from external sources such as exposure to X-rays, ozone, cigarette smoking, air pollutants and industrial chemicals.

Free radical formation occurs continuously in the cells as a consequence of both enzymatic and non-enzymatic reactions (Figure 1). Enzymatic reactions which
serve as sources of free radicals include those involved in the respiratory chain, in phagocytosis, in prostaglandin synthesis and in the cytochrome P450 system. Free radicals also arise in non-enzymatic reactions of oxygen with organic compounds as well as those initiated by ionizing radiations. Some internally generated sources of free radicals are [1]:

mitochondria
phagocytes
xanthine oxidase
reactions involving iron and other transition metals
arachidonate pathways
peroxisomes
exercise
inflammation
ischaemia/reperfusion.
Some externally generated sources of free radicals are [1]:

cigarette smoke
environmental pollutants
radiation
ultraviolet light
certain drugs, pesticides, anaesthetics and industrial solvents
ozone.

With electrons unhinged, free radicals roam the body, wreaking havoc. The free radical, in an effort to achieve stability, attacks nearby molecules to obtain another electron and, in doing so, damages those molecules. This situation can be compared to letting a bachelor into a dance where people have come as couples. The bachelor begins cutting in, each time leaving another bachelor, so the breaking up of couples spreads through the dance floor.

If free radicals are not inactivated, their chemical reactivity can damage all cellular macromolecules including proteins, carbohydrates, lipids and nucleic acids. Their destructive effects on proteins may play a role in the causation of cataracts. Free radical damage to DNA is also implicated in the causation of cancer and its effect on LDL cholesterol is very likely responsible for heart disease. In fact, the theory associating free radicals with the aging process has also gained widespread acceptance



Eat a balanced diet. Include plenty of fruits and vegetables in your diet. Eating lots of fruits and vegetables may have a modest effect in preventing cataract development, though this hasn't been definitively proved.
In one study, lead scientist Paul Jacques, DSc, director of the Nutritional Epidemiology Program at the Center, and his colleagues analyzed the diets and examined the eyes of a group of Boston-area women over the course of five years. Among the study participants, who were all members of the larger Nurses' Health Study, women who reported supplementing their diets with vitamin E (a powerful antioxidant) for 10 years or more had significantly less progression of cataract development at the five-year follow-up exam. A similar relative decrease in cataract progression was seen in women who reported higher intakes of two of the B vitamins, riboflavin and thiamin, when compared to women with lower intakes.
There is considerable interest in the role of antioxidant vitamins in the development of cataracts. Antioxidants neutralize the action of free radicals, thereby preventing damage to cells, and may be relevant to cataracts if oxidative damage to the lens is found to lead to cataract formation. Antioxidants are found naturally in food and include vitamin C (ascorbic acid), vitamin E (alpha-tocopherol), carotenoids, and anthocyanidins.

Protect yourself from the sun. Ultraviolet light may contribute to the development of cataracts. Whenever possible, wear sunglasses that block ultraviolet B (UVB) rays when you're outdoors.

Take care of other health problems. Follow your treatment plan if you have diabetes or other medical conditions. If you have a chronic illness, it's especially important that you take other preventive steps, such as wearing UVB-blocking sunglasses when outdoors and not smoking.

Researchers are continuing to explore new ways to prevent and treat cataracts, such as developing medications that would reduce or eliminate the need for surgery. But, until such a treatment exists, your chances of fully restoring your vision with cataract surgery are excellent if you have no other eye diseases.