CONJUNCTIVA

CONJUNCTIVA

What is it?          

GROSS ANATOMY:

The conjunctiva is a transparent, mucous membrane which has many blood vessels. It covers the inner surface of the eyelid as well as the sclera. The conjunctiva receives nourishment from minute blood vessels almost invisible to the naked eye

When the eye becomes extremely red, this is a condition called Conjunctivitis.  The blood vessels will appeal dilated and there will be a rapid inflammation response.

          LAYERS:

(1)     Epithelial Layer:   has goblet cells that produce   mucin.

(2)     Stromal:  has accessory lacrimal glands of Kraus and Wolfring 

The conjunctiva is made up of three sections;

(1)     Palpebral—continuous with skin of eyelids (posterior surface)

-contain meibomian glands (yellow)

-connected via puncta and lacrimal passage to the nose

The palpebral conjunctiva is thicker compared to the bular conjunctiva

(2)      Bulbar Conjunctiva—covers sclera or the anterior part of the eyelids sclera collects fat—yellow in elderly, bluish in babies.  The bulbar conjunctiva is thinner and thus able to easily slide back and forth across the anterior part of the eye.  Due to the transparency of the bulbar conjunctiva, the blood vessels beneath are easily seen.  The bulbar conjunctiva contain Goblet Cells which produce mucin

(3)     Fornix—The junction where the upper and lower eyelid meet, there is a loose pocket of        conjunctiva.  This allows for free movement of the eyeball          

CONJUNCTIVAL INFECTIONS:

The commonly used term to describe a conjunctival infection is ‘pink eye.‘

In this condition, the conjunctiva is inflamed and there is an infection of some type to be determined. Conjunctival infections include:  allergies, Vernal/Viral Conjuctivitis, Giant Papillary Conjunctivitis (GPC), Subconjunctival Hemorrhage.  The signs and symptoms can aid in determining the nature of the infection.  Typically, the infection is caused by a bacteria, virus or fungus. Adults commonly contact bacterial and viral conjunctivitis.  When a person catches a cold or has an ear infection, it is the same bacteria that can cause infectious conjunctivitis. This is a commonly occurring problem which eye care practitioners routinely treat.

 

BACTERIAL CONJUNCTIVITIS

Bacterial conjunctivitis, for the most part is self-limiting although, it can sometimes be more serious.  The bacteria responsible for this is called  Staphylococcus or Pneumococcus.  Even bacteria which are known to cause sexually transmitted diseases (STDs) such as Chlamydia or Gonorrhea, can be the cause of infectious conjunctivitis. This type of  infection is highly contagious and the bacteria can be transferred quickly from one eye to both and then to other surfaces finally affecting the eyes of others. In children, bacterial conjunctivitis is more common than viral and is mainly caused by H. influenzae, S. pneumoniae and M. catarrhalio

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Signs and Symptoms

·         unilateral initially then spreads to both eyes

·         brilliant red conjunctiva

·         contagious acute onset, self-limiting

·         lids are closed in sleep, increase in     temperature- bacterial growth increases

·         pus and sticky eyelids

·         tear production increases

·         few pain fibres (looks red, doesn’t hurt very much)

·         scratching, burning and itching

·         photophobia (if cornea also infected)

·         pus produced from goblet cell mucous and inflammatory cells

·         hyperemia-lessens near limbus

·         pseudoptosis

TREATMENT:  Treat with anti-biotics

 

NONINFECTIOUS CONJUNCTIVITIS

Unlike infectious conjunctivitis, non-infectious conjunctivitis is not contagious and cannot be spread to someone else by hand to eye contact.  Simple Red Eye (irritative conjunctivitis) can be caused by dust, pollution, fatigue, dry air, alcohol consumption or chlorine in swimming pools.

Non-infectious conjunctivitis may also be caused as an allergic reaction to something.  

ALLERGIC CONJUNCTIVITIS:

This type of non-infectious conjunctivitis is caused by seasonal allergy to pollen or plants often during the spring or summer months. One may also be allergic to the preservatives in eye drops or eye solutions as well, as can be allergic to protein build up on contact lenses.

 

Signs and Symptoms:

·         bilateral, sparse, weepy exudates

·         milky red conjunctiva

·         swelling, pain

·         contact/chemical sensitivities

·         allergies, hay fever, asthma

TREATMENT:  Treat with antihistamines, topical cortisone 

 GPC (GIANT PAPILLARY CONJUNCTIVITIS)

 

 

This is a form of allergic conjunctivitis and is routinely found in extended soft contact lens wearers.  What happens is that the eye reacts to the protein or other contaminant build-up on the surface of the soft contact lens.   This results in GPC which is characterized by the enlarged and dramatic formation of  papillae underneath the upper eyelid.  This form of conjunctivitis is often treated with reducing the length of time the contact lenses are being worn as well as cleaning the lenses regularly with enzymatic cleaners.  The patient may also be told to change the contact lens solution to see if this makes a difference.

VIRAL CONJUNCTIVITIS

Viral conjunctivitis is typically caused by the adenovirus. Other viruses that may also cause this type of  conjunctival infection include herpes simplex virus (HSV), varicella-zoster virus (VZV), picornavirus (enterovirus 70, Coxsackie A24), poxvirus (molluscum contagiosum, vaccinia), and human immunodeficiency virus (HIV).  Similar to bacterial, viral conjunctivitis is also contagious and may spread from 10-12 days from onset.   Eye care practitioners warn patients to avoid touching their eyes, shaking hands, and sharing towels.  The infection may be transmitted through inoculation of viral particles from the patient's hands or by contact with infected upper respiratory droplets, fomites, or contaminated swimming pools. The infection usually resolves spontaneously within 2-4 weeks.

 
Signs and Symptoms: 

• Itchy eyes
• Tearing
• Redness
• Watery discharge
• Light sensitivity
• Gritty sensation

TREATMENT

Treat with eye drops and eye rinses in the initial stages. Severe infections involving Herpes Simplex virus are treated with oral antiviral medicines. Other viral conjunctivitis medicines include drugs like Zovirax, Dendrid, Viroptic and Vira-A.

 

 

KERATOCONUS

WHAT IS KERATOCONUS?

 

 

 

Kertoconus is a rare, inherited eye disease which affects approximately 1 in 7000. The cornea starts to progressively get thinner and begins to bulge outwards.  It is the conic deformity which prevents light from coming through the lens undistorted.  When light enters the eye, it cannot focus properly and this results in blurry vision.  The progressive, bilateral thinning of the cornea causes irregular astigmatism and possible perforation. This optical problem may be corrected with contact lenses but may eventually require a corneal transplant or Keratoplasty.

 

Keratoconus begins in adolescence, usually with one eye first then goes through various stages of remission and relapse before stabilizing around the age of 40-45.  Both females and males are equally affected.  The irregularity of the cornea makes the vision so hard to correct.  If left untreated, this disease may cause permanent vision loss requiring corneal transplantation.

 

 

This disease can be classified by the degree of conicity of the apex of the cornea:

 

STAGES OF ADVANCEMENT OF KERATOCONUS:

 

Stage 1- Oblique astigmatism is noted

Stage 2- Vision is not refractable to normal

Stage 3- Pronounced conical shape with corneal thinning

Stage 4- Opacities at the apex

Mild:  (up to 45D), moderate (between 45 and 52D), advanced (between 52 and 60D) and severe (over 60D)

 

SIGNS AND SYMPTOMS OF KERATOCONUS

 There are three associated conditions of Keratoconus

a.)  Munson Sign:  cone visible when eye looks downward, eye protrudes in lower lid

b.)  Fleisher’s Ring:  Rust colour ring—iron deposits at base of cornea in corneal epithelium

c.)   Hydropes:   abnormal and sudden gathering of fluid after Descemet’s membrane and endothelium break--The fluid accumulates in the corneal tissue

·        Blurred vision with glasses—inability to correct    vision in young person to 20/20 with spectacles

·        frequent prescription changes

·        vertical straie

·        Distorted keratometer mires

·        high astigmatism

·        central corneal thinning

·        oblique axis

·        small mires

·        asthenopia

 

Rigid gas permeable (RGP) contact lenses are commonly used to aid in the correction of keratoconus.   RGP lenses are generally well tolerated and have a high success rate.  However, they don’t work for all patients since some patients are not comfortable with the fit and depending on the stage of advancement of the disease, RGP lenses may cause discomfort and compromise the corneal integrity.  This would mean the patient would need to seek alternative options for this condition. 

An alternative to the RGP lenses is the piggyback system of fitting contact lenses.  This system consists of a rigid gas permeable lens placed on top of a soft contact lens.  This method of fitting was first introduced in the early 1970s for patients who could not tolerate RGP or scleral lenses.  At that time, limited options were available to patients consisted of mainly low DK lenses that resulted in corneal hypoxia.

HOW MUCH DO YOU KNOW???

TEST YOUR KNOWLEDGE ON EYES

All answers found in the blog since inception.

      1.       An eye specialist that performs surgery on the            eye is called an  __________________________.

2.       Close to _______________per cent of cataract surgeries successfully result in better vision.

3.       An eye specialist that fills the prescription for a pair of glasses is called an_______________________.

4.       An astigmatic cornea is shaped like a football/soccer ball

5.       Myopia is an eye condition in which you have trouble seeing clearly in the ______________distance.

6.       A  plus/minus lens is used in the correction of hyperopia.

7.       T/F (True or False)  The function of fusion is necessary to see in 3D.

8.       What is the meaning of visual acuity of 20/20?

9.       T/F Being able to see 20/20, is having perfect vision.

10.   Name the leading cause of blindness in North America.

11.   A person unable to see in 3D, does not have any ____________perception.

12.   What is the Snellen Chart used for?

13.   What is visual acuity the measurement of?

14.   The second most common cause of permanent vision loss is called ______________________.

15.   The sclera is part of the ___________________tunic.

16.   The ________________is transparent and covers the iris, pupil and anterior chamber.

17.    A procedure used to help the elderly with sagging skin on the upper eyelids which may interfere with vision is called ____________________________.  This is more commonly performed as a cosmetic procedure.

18.   T/F  Presbyopia commonly occurs around the age of 40

19.   The external retina is made up of two cell layers.  Name them.

20.   A method used to fit frames cosmetically is called the theory of ______________________.

21.   Ultraviolet radiation measuring a wavelength of less than __________________nm is the most biologically harmful.

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