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.