Driving & Defective Eyesight

As expected, Malaysian law is as informative as a nut.

So here's UK law, mind-mapped because I needed an excuse to try out the mind-mapping software, followed by the criteria used to assessed eyesight.



Eyesight requirements
The following requirements apply to holders of licences for cars and motorcycles. It is a criminal offence to drive a vehicle on the road if you cannot meet these eyesight requirements

Visual acuity
You must be able to read in good daylight, with the aid of glasses or contact lenses if worn, an old style standard vehicle number plate at a distance of 20.5 metres (67 feet) or a new style number plate at a distance of 20 metres (65 feet) where narrower characters are displayed. New style number plates were introduced on 1 September 2001 and start with two letters; for example AB51 ABC.
This is the standard eyesight requirement for someone taking a driving test.

Field of vision
You must have a good all-round field of vision for safe driving to ensure that you are aware of approaching vehicles and other hazards. You must report to the DVLA any significant loss of field of vision when you have both eyes open. This is likely to apply to people with eye conditions where there are defects in the field of vision, including severe glaucoma or retinitis pigmentosa.

Monocular vision
You must notify the DVLA if you have lost sight in one eye. You may drive provided you have good sight in the other eye and can meet the eyesight requirement; the field of vision in the other eye is normal; and when advised by a doctor or eye specialist that you have had enough time to adapt to the loss of sight in one eye.

Visual field defects
Included here are conditions such as severe glaucoma or retinopathy in both eyes, retinitis pigmentosa and others. You must be able to meet the recommended national guidelines for visual field before you can drive.

Cataract
If your sight is affected by cataract or post-cataract surgery, you must be able to meet the standard eyesight requirement above. The effect of glare on your sight may mean you are not able to meet the requirement.

Night blindness
You must notify the DVLA if you are unable to meet the above standards for visual acuity and field of vision, in all conditions.

Diplopia (double vision)
You must stop driving when this is first diagnosed. You may be allowed to drive if it is confirmed to the DVLA that your diplopia is controlled by glasses, or by an eyepatch you have adapted to wearing and which you undertake to wear when driving.

Colour blindness
It is not necessary to notify the DVLA of colour blindness.

Blepharospasm (involuntary blinking or closure of eyelids)
You may continue to drive provided satisfactory medical reports are submitted. You must however inform the DVLA of any change in the condition.

Appealing against a refused driving licence
If you are refused a driving licence or your licence is revoked because of your sight loss, you do have a right of appeal to a Magistrates Court (or Sheriff Court in Scotland). It is important to remember, however, that the Courts cannot overturn what is set down in law. You should seek expert advice at this stage and your local Citizens Advice Bureau or Law Centre can help.

Courtery of http://www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_scacdrivingvisreqs.hcsp.

Signs and symptoms

A cataract usually develops slowly and causes no pain. At first, the cloudiness may affect only a small part of the lens (a clear, elliptical structure near the front of each eye) and you may be unaware of any vision loss. Over time, however, as the cataract grows larger, it clouds more of your lens and distorts the light passing through the lens. Eventually, this impairs your vision because of overall blur or image distortion.

Signs and symptoms of cataracts include:

* Clouded, blurred or dim vision
* Increasing difficulty with vision at night
* Sensitivity to light and glare
* Halos around lights
* The need for brighter light for reading and other activities
* Frequent changes in eyeglass or contact lens prescription
* Fading or yellowing of colors
* Double vision in a single eye

If you have a cataract, light from the sun, lamps or oncoming headlights may seem too bright. Glare and halos around lights can make driving uncomfortable and dangerous. You may experience eyestrain or find yourself blinking more often to clear your vision.

Cataracts don't typically cause any change in the appearance of your eye. Pain, redness, itching, irritation, aching in your eye or a discharge from your eye aren't signs or symptoms of a cataract, but may be signs and symptoms of other eye disorders.

A cataract isn't dangerous to the physical health of your eye unless the cataract becomes completely white, a condition known as an overripe (hypermature) cataract. This can cause inflammation, pain and headache. A hypermature cataract requires removal if it's associated with inflammation or pain.

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.