GLAUCOMA

GLAUCOMA

This condition is the second most common cause of permanent vision loss.

 
Glaucoma is a disease in which there is optic nerve damage which cannot be reversed. The optic nerve is responsible for the function of carrying visual impulses from the nerve to the brain.  The majority of the cases experience visual loss due to an increased pressure in the eye, called intraocular pressure or IOP.

There are 4 types of  Glaucoma:

• Open-angle (chronic) glaucoma
• Angle-closure (acute) glaucoma
• Congenital glaucoma
• Secondary glaucoma

The clear fluid which fills the anterior part of the eye is called aqueous humor.  This liquid is produced by the iris and exits the eye through an area called the anterior chamber angle or just the angle.  Anything that slows or blocks the flow of this fluid out of the eye will cause pressure to build up in the eye. This pressure is called intraocular pressure (IOP).  In most cases of glaucoma, this pressure is high and causes damage to the optic nerve.

Open-angle (chronic) glaucoma is the most common type of glaucoma.

 RISK

Certain factors can make it more likely that a person may develop Glaucoma.  Those risks include:

 

• Having family history of glaucoma damage
• having optic nerve or visual field findings on the border between glaucoma and normal
•  African-American ethnic background
• Being myopic (near-sighted)
• Having a thin cornea
• Being at higher risk of developing high IOP due to a condition in which pigment is dispersed  

If glaucoma is caught when the signs are very early and treatment begun at that time, the risk of developing serious visual loss is quite small.

OPEN ANGLE GLAUCOMA:      

This is the most common type and constitutes about 90per cent of all cases.  The patient experiences no real symptoms but the IOP

becomes elevated until visual loss occurs.  This happens in both eyes or the condition is bilateral.  This is caused by the degeneration or rigidity of trabecular meshwork, Schlemm’s canal and venous channels.  Although the production of aqueous is constant, the outflow decreases so IOP goes up. The treatment for this condition is usually prescribed drops or surgery. 

The drops help to reduce production of aqueous and increase drainage through outflow channels.  Drops commonly prescribed are called Diamox which is a miotic drug.

ANGLE CLOSURE GLAUCOMA:

 This condition results in a sudden increase in IOP due to blockage of anterior chamber angle.  Unlike Open Angle Glaucoma, this type has very pronounced and deliberate symptoms.  All outflow of aqueous ceases or stops.  This immediately increase the IOP which causes pain and visual loss.  This usually develops in patients with a narrow (shallow) anterior angle.  There is a sudden onset of symptoms which include a swollen, edematous cornea, reddening of the eye, nausea and vomiting.  The treatment includes dehydrating the eye and using a miotic drug which pulls the iris away from canal of Schlemm.  Surgery is also an option.

 

 

CATARACT

 Condition:  Cataract

 

 

This is a naturally occurring condition which happens as one ages.  In this condition, the lens, located behind the iris and pupil, becomes opacified or appears cloudy due to the dead cells gathering in the lens.

This common condition results in vision loss for patients over 40 years of age.   World-wide, cataracts is one of the leading causes of vision loss.  Others include Macular Degeneration, glaucoma and diabetic retinopathy.  Statistics show that approximately 244,000 cataract operations were performed in Canada in 2001 (National Coalition for Vision Health, 2005).

 

Other Causes

Other causes of cataract which may result in an earlier age may be due to prolonged and excessive ultraviolet light exposure, diabetes, smoking and use of certain medications.  These medications generally include steroids, statins and phenothiazines. 

 

Cataract Surgery

 

Surgery is the only way to remove cataracts in order to restore vision. Cataract surgery is routinely performed and is commonplace in the United States and Canada.  The success rate of this surgery is quite high. Close to 95 percent of cataract surgeries successfully result in better vision.  Cataract surgery involves the removal of the opacified lens replaced with an artificial lens called in intraocular lens or IOL. 

 

Procedure

 

With advances in medicine, the modern cataract procedure is called Phacoemulsification.  This involves using a high frequency ultrasound probe which obliterates the cloudy lens into tiny fragments which are then taken out from the eye with suction.

 As with other surgeries, cataract surgery also has a risk of complications.  This risk is increased if there is a pre-existing eye disease or other medical condition.  However, complications are usually dealt with successfully. 

Recently, a new way to remove cataract has emerged which uses a Femtosecond laser, which is similar to the LASIK procedure.  This new method, approved by the FDA, is even more reliable in terms of accuracy and safe. 

Recovery

The procedure is quite quick and lasts approximately 15 minutes.  Medicated eye drops are prescribed to be used for a period of a few weeks after surgery.  A protective shield must be worn while sleeping for about 7-10 days after surgery.  Post-operative sunglasses are to be worn for protection from the sun and other light sources during eye recovery.

Types of Cataracts

• A subcapsular cataract is located at the back of the lens. Those most likely to get this type of cataract are diabetics or those taking high doses of steroid medications.
• A nuclear cataract as the name suggests, this type of cataract forms deep in nucleus of the lens. Nuclear cataracts are usually associated with aging.
• A cortical cataract occurs in the central nucleus of the lens.  Wedge shaped opacities appear in the periphery of the lens and move towards the center.

 

LOW VISION

WHAT DOES LOW VISION MEAN?

Low vision is not ‘bad vision.’  It is simply vision that cannot be corrected with visual aids to achieve 20/20 visual acuity.  There only exists the means to enhance or provide low vision aids to improve the quality of life for those going through vision loss.

It is a visual impairment that cannot be corrected by standard glasses, contact lenses, medicine or surgery.  Having low vision interferes with a person’s ability to perform everyday activities.  It has an impact on lifestyle and thus a low vision aid patient requires aids to help enhance the amount of vision they do have.

STATISTICS

·        1 out of 20 people in America has low vision

·        1 in eight Americans is 65 years of age or older

·        By 2030, number of people 65 years and older is expected to double

(Lighthouse National Survey on Vision Loss 1995)

·        More than 22 billion dollars is spent annually on care and services for people who are blind or visually impaired

    EARLY SIGNS:

Often times, depression and low self-esteem set in when a person is first diagnosed with vision loss.  Other emotions such as anger, fear, and grief are also experienced and are entirely normal.  Often, people’s reactions to vision loss are similar to those experienced in bereavement; initially, there is often a period of denial, when the person experiencing visual loss is in shock and believes their state is not permanent.   Things that were previously routine, such as performing household chores, taking care of children, reading the newspaper, or going to the corner store, may all become very challenging tasks.  Cooking, exercising, and socializing may even seem impossible.

COPING WITH VISION LOSS

 Vision loss requires a person to cope with an increased amount of stress while being able to function in an environment with fewer stimuli.  Relationships with loved ones often become strained.  Without proper assistance, people who experience the disintegration of important relationships may end up living in fear and may become homebound. This is particularly true of seniors.

Those suffering from vision loss require rehabilitation to restore the skills they need to perform everyday activities, to restore their quality of life, and to bring about a sense of normalcy.  Of great concern to many who suffer vision loss, is the idea of losing their independence.  Depending on the degree of vision loss, a caregiver or someone to help out may be required in the interim or on a permanent basis.  A move to a short or long-term care facility is an alternative.

 

Vision loss is incredibly difficult to fathom and accept. Those in denial are at risk of increased difficulties, as their recovery from vision loss is undermined by their lack of motivation to rehabilitate. The most important step for anyone in this situation is to seek support.  Things are incredibly difficult for those who are alone and need help.  Dealing with the resultant emotions alone can be as burdensome as dealing with the vision loss

CHILDREN

Low vision aids is the solution to visual loss.  Vision loss is not restricted only to the ageing population.  In fact, a child’s visual requirements are just as important if not, more important than that of adults.  Certain conditions, if caught early enough may be preventable and treatable.  According to research, approximately 25% of school age children have some sort of visual problem and six out of ten children have difficulty reading due to a visual problem that is either uncorrected or undetected.

Vision screening in pediatrics is important in the early detection of a condition known as Amblyopia or ‘lazy eye.’ Amblyopia is a functional defect most commonly caused by strabismus or unequal refractive error.  This condition is the leading cause of unilateral vision loss in people between the ages of 20-70.  If caught in the early stages, treatment can begin which can increase the child’s chance of improving their vision.  If the condition remains untreated, or is treated for best possible vision, the child may still be able to improve the quality of their vision with low vision aids.

     CAUSES: 

-Macular Degeneration, Cataract, Problem with optic nerve (Glaucoma, Diabetic Retinopathy)

          -inherited disorder of receptor cells—Retinitis Pigmentossa

 VISUAL ASSESSMENT:

          Optometrist or Ophthalmologist will test the patients for low vision correction.    They must determine what type of field defect:

• Macular Degeneration:  Central Field Defect—peripheral still intact 
•  A condition called Diabetic Retinopathy is on the rise with children and elderly—several scotomas spread around
• Glaucoma:  Peripheral Field Defect—you want minification to shrink the text into the center of good vision
•            Retinitis Pigmentossa:  All over defect

.           Once you determine where the visual field defect is, then you know how to help the patient via low vision aid.  i.e. if the blind spot is in the center, use a magnifier to get it out of the area of the scotoma.    i.e. if the blind spot is in the periphery, use a minifier—to shrink things so that they fall into the center

 HIGHER RISK FOR LOW VISION
                ·        people 65 years of age or older (age related Macular Degeneration)

·        African American and Hispanics over the age of 45

·        genetically higher risk for developing diabetes and diabetic retinopathy

·        African American higher risk of developing Glaucoma