Pharmacotherapy/Treatment Of Non Infection Eye Disease
The eye is the organ of sight. Some say it is the most important organ of the body. The word "eye" comes from the teutonic "auge." The eye has a number of components. These components include but are not limited to the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous.
Eye Anatomy
The anatomy of the eye is complex. The main structures of the eye include:
Cornea: clear tissue in the very front of the eye
Iris: colored part of the eye surrounding the pupil
Pupil: dark hole in the iris that regulates the amount of light going into the eye
Lens: small clear disk inside the eye that focuses light rays onto the retina
Retina: layer that lines the back of the eye, senses light, and creates electrical impulses that travel through the optic nerve to the brain
Macula: small central area in the retina that allows us to see fine details clearly
Optic nerve: connects the eye to the brain and carries the electrical impulses formed by the retina to the visual cortex of the brain
Vitreous: clear, jelly-like substance that fills the middle of the eye
Eye Disease
Eye disease is very common. But most people worry more about eye infection. To put it in statistics, the leading cause of low vision and blindness in the United States of America (USA) are age rated eye disease.
Symptoms
The range of symptoms are many. From itchy eyes to watery eyes and so on.
Diagnosis
There are many types of eye disease. There are many ways to diagnose different types of disease. A medical doctor takes a patient's history and other health-related information with the symptoms before deciding on which diagnosis will be right to predict the type of eye disease.
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Using a solution put into the eyes to dilate it for examination is the most common way to diagnose eye disease. A handheld microscope can be used to examine the inside of the eye.
Common Eye Disease
Refractive Errors
Refractive errors make it hard to see clearly. This occurs due to a change in the shape of the eyes. Light then finds it difficult to focus on the retina. Many people experiencing it don't know they can see better.
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| Refractive error Wiki |
Types
1. Myopia (near or shortsightedness). It is the ability to see close objects but cannot see far objects. Begin at childhood
2. Byopia (far or long-sightedness). It is the ability to see far objects but cannot see near objects.
3. Astigmatism (cannot see far and near object)
4. Presbyopia (middle age and older adults can't see things up close). More common in people above 40 years
Symptoms
1. Double vision
2. Hazy vision
3. Headache
4. Squinting
5. Eye strains
6. Trouble focusing when reading or looking at a screen
7. Seeing glare or halo around bright light
Risk Factors
Family history
Causes
There are different causes of refractive eye error. They are;
1. Eyeball grows too long or short
2. Cornea shape changes
3. Lens age
Diagnosis
Eye test that utilizes letters of different size and shape to be identified from a distance.
Pharmacotherapy/Treatment
Eye glasses
1. Reading glasses for presbyopia
2. Single vision prescription lenses which correct one long or short shortsightedness
3. Multifocal prescription lenses correct both long and shortsightedness
4. Bifocal lenses correct near vision (bottom) and distance vision (top)
5. Trifocal lenses correct near vision (bottom), distance vision (top) and in-between vision (middle)
6. Progressive lenses (multifocal) don't have a visible line between near and far vision
Contact lenses
Hard: hard material makes it less likely to tear with a crisp vision. It is hard to clean.
Soft: they are soft and flexible. Easy to clean.
Daily wear (single use) contact lens: use during the day and discard at night
Daily wear (reusable) extended contact lens: use during the day and clean at night for the next day use for up to a month.
Surgery
Laser surgery is theuthe of laser to change the shape of the cornea. It is called laser assisted in situ keratomileusis. This procedure is not suitable for presbyopia. The eye is made stable and a strong beam of light is passed through it.
Other types of surgery;
1. Photorefractive keratectomy and laser-assisted subepithelial keratectomy (LASEK)
2. EPI-LASIK
3. Photorefractive keratectomy (PRK)
4. Phakic intraocular lens (PIL) implantation. It is called phakic because the eye natural lens is left untouched.
Age-Related Macular Degeneration (AMD)
This eye disease affects special activities like reading and driving. These activities require sharp central vision. AMD affects the macular of people above 50 years. It does not lead to blindness but makes it harder to see things like reading. It progresses slowly but some experience sharp vision loss. It can happen to one or both eyes.
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| Macular Degeneration Wiki |
Types
1. Wet AMD: this is an abnormal blood vessel behind the retina that starts to show under the macula. This intimately leads to blood and fluid leakage. Bleeding, leaching and scarring from these blood vessels cause damage and lead to rapid central vision loss. It's major symptoms are the appearance of straight lines appearing wavy.
2. Dry AMD: occurs when macula thins overtime as part of the aging process, gradually blurring in vision. It is more common and affects 70-80 % of people. It is usually slow and affects both eyes. One of the symptoms is drusen.
Drusen are tiny yellow or white deposits under the retina. A single drusen is not a problem. When they become many, they can affect the vision.
Symptoms
A blurry area near the center of the vision that may get bigger with time. The eye can no longer see the bright spot.
Risk Factors
1. Family history
2. Caucasian descent
3. Smokers
Diagnosis
An eyedrop like atropin to dilate the eyes before examination. An optical coherence tomogram (OCT) can be done to take pictures of the inside eye. Side effects of the eyedrop are eyes sensitive to light for some hours.
Pharmacotherapy/Treatment
There is no available treatment. Management is the use of dietary supplements (vitamins and minerals). Advanced age related eye disease studies (AREDS) came up with a combination of supplements suitable for slowing progression of AMD conditions named AREDS 1 and AREDS 2. The combinations contain high dose vitamins and minerals such as vitamin C, vitamin E, beta-carotene, copper, lutein, zeaxanthin and zinc. Low vision devices and rehabilitation (training) programmes is also recommended.
For wet or neovascular AMD, Anti–vascular endothelial growth factor therapy, also known as anti-VEGF therapy or anti-VEGF medication, is the use of medications that block vascular endothelial growth factor. This is done in the treatment of age-related macular degeneration. The drug can be injected into the eyes every month.
Another treatment option is the use of laser called photodynamic therapy (PDT). Verteporfin is a light sensitive medicine that turns on when hit by a cold laser. The verteporfin is injected into a blood vessel in the arm. A numbing medicine is instilled into the eye. A special type of contact lens is placed in the eyes to help guide the laser beam into the right spot. Cold laser is shone onto a very sensitive portion at the back of the eye where there is the medicine called verteporfin. This is meant to break down the extra blood vessels at the back of the eyes.
Cataract
A cataract is a cloudy area in the lens of the eyes. Cataract affects older persons. They make visions blurry, hazy or less colourful. Reading becomes a problem. It affects one or both eyes. It is the leading cause of eye surgery, vision loss and blindness worldwide. It can occur at any age even at birth.
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| Cataract Mayoclinic |
Symptoms
1. Cloudy vision
2. Blurry
3. Colour looks faded
4. Can't see well at night
5. Lights seems too bright
6. Halo appear around lights
7. Double vision
Causes
It begins when the protein in the eyes begins to break down and clump together. The clump forms a cloudy mass in the lens that makes it difficult to see well.
Risk Factor
1. Diabetes
2. Smoke
3. Alcohol
4. Family history
5. Eye injury
6. The use of steroids
7. Staying under the sun
Diagnosis
The eye is dilated and then examined using an otoscope
Pharmacotherapy/Treatment
1. Use bright light at home or work
2. Wear anti glare sunglasses
3. Use magnifying glasses for reading and other activities
4. Change glasses often
5. Surgery to remove the cloudy lens and fix an artificial lens also called intraocular lens, IOL. This surgery is safe.
Healthy eating, use of hats under the sun and quitting smoking are some of the ways to prevent cataract. Pirenoxine is an eyedrop that have been shown to prevent cataract in people below 60 years but the benefits for people above this age is not much.
Diabetes Retinopathy
Diabetes affects the blood vessels in the retina. This leads to vision loss and blindness.
Symptoms
Early stage does not present with symptoms. Symptoms begin with trouble reading or seeing faraway objects. Blood vessels begin to bleed into the vitreous humour and appear as dark, floating streaks like cobwebs. These early symptoms may disappear and reappear again until it becomes worse. If not treated, the blood can cause scarring.
Stages
1. Mild nonproliferative retinopathy (microaneurysm)
2. Moderate nonproliferative retinopathy causes blockage in some retinal vessels
3. Severe nonproliferative retinopathy causes more blockage in some retina blood vessels depriving retina from blood supply leading to growing new blood vessel
4. Proliferative retina is most advanced
Complications
1. Over half of people with diabetes retinopathy will experience diabetes macular edema. This is when the retina leaks fluid into the macula.
2. Neovascular glaucoma: abnormal blood levels to grow out of the retina and block fluid from draining out of the eye.
3. Retinal detachment: scars form in the back of the eye peeling the retina away from the back of the eye.
Risk Factors
Diabetes
Diagnosis
Dilate the eye using eye drops for physical examination of the eye.
Pharmacotherapy/Treatment
Available treatment cannot undo damage but can prevent further damage. The first attempt is to control diabetes. This includes medication and lifestyle adjustment. Also, blood pressure and cholesterol level must be controlled as these play a role in diabetes.
Anti VEGF can slow down or reverse diabetes retinopathy. VEGF is known to cause leaking blood vessels and swelling in the macula in both eyes. Examples of anti VEGF are bevacizumab, ranibizumab, and aflibercept. Other drugs are corticosteroids such as dexamethasone eye drop for inflammation response.
Surgery can also be of help. Cataract and glaucoma surgery should be considered before initiating other surgery such as laser treatment and vitrectomy. Vitrectomy removes vitreous humour after laser (panretinal photocoagulation) or freeze treatment is used to reattach the eye or repair the retina. The vitreous humour is replaced with a fluid like silicon oil. Another method is to inject a bubble of gas or air into the eye to hold the retina in place.
All the treatment options have their own side effects. For example, laser treatment can cause loss of peripheral (side) vision, colour vision and night vision.
To prevent pain, the eye is numb. Recovery is within a day. The person may experience minor pain, swollen eye, red eye or blurry vision for weeks. To reduce some of these side effects, eye patches are recommended. Also, the use of drops like corticosteroids can reduce swelling and prevent infection. It is advisable to avoid flying in the air and keep the head in one spot after the surgery for weeks.
Glaucoma
Glaucoma is a progressive degenerative eye disease that can cause vision loss and blindness. It leads to damage of the nerve at the back of the eye called optic nerve. This increases the pressure of the eye. It can affect one or both eyes.
Not everyone with increased eye pressure has glaucoma and not everyone with glaucoma has increased eye pressure.
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| Glaucoma Wiki |
Types
There are different types of glaucoma. They are;
1. Open angle glaucoma
2. Close (narrow) angle glaucoma
3. Congenital glaucoma
Symptoms
There are no early symptoms. It begins with vision loss to the peripheral. This leads to inability to see things with the side of the eye. Others are intense eye pain, upset stomach (nausea), red eyes and blurry vision.
Risk Factors
1. Family history
2. Black American or Latino community over 40 years of age
3. Those over 60 years of age
Diagnosis
Physical examination of the side of the eyes.
Pharmacotherapy/Treatment
There is no cure. Treatment option is to prevent further degeneration of the disease. Treatment options are based on so many factors.
Drugs
All the drugs are eye drops.
1. Prostaglandins e.g. latanoprost
2. Rho-associated kinase inhibitors e.g. netarsudil
3. Nitric oxides e.g. latanoprostene bunod
4. Miotic or cholinergic agonist e.g. pilocarpine
5. Alpha adrenergic against e.g. brimonidine
6. Beta blocker e.g. timolol
7. Carbonic anhydrase inhibitors e.g. dorzolamide
Some health care practitioners include eye supplements such as lutein and zeaxanthin containing oral drugs.
Surgery
1. Trabeculectomy: some mesh taken out to allow space for fluid to escape.
2. Drainage implant surgery: is the use of a tube place inside the eye to drain fluid out. There are minimal invasive implants.
3. Electrocautery: the tiny tubes that normally drains the eyes is cut to encourage more drainage.
Laser surgery
1. Argon laser trabeculoplasty (ALT): open clogs in the eyes so that fluids can drain out.
2. Selective laser trabeculoplasty (SLT): beam a low level laser onto the spot there is pressure in the eye.
3. Laser peripheral iridotomy (LPI): narrow angle glaucoma is when the distance between the iris and cornea becomes small due to eye pressure. Laser beam is directed at the iris to drain off the fluid.
4. Cyclophotocoagulation: beam a laser into a structure inside your eye to ease pressure.
Dry Eye Syndrome
Dry eye syndrome happens when the body fails to produce enough tears or in some other situation, quality tears. Vision becomes impaired while viewing television, in air condition room or when traveling.
Symptoms
1. Red eyes
2. Photophobia
3. Blurred vision
4. Eye fatigue
5. Burning, scratchy and stinging sensation in the eyes
Pharmacotherapy/Treatment
The use of artificial tears is the first step in fighting dry eye syndrome. Others are lifitegrast and cyclosporin with corticosteroids.
The use of silicon based punctal plugs inserted into the eyes during surgery helps to prevent tears from escaping. It is used to plug tears ducts at the corner of the eyes.
Conjunctivitis
Conjunctivitis is also known as pink eye. This is a situation whereby the tissues lining the back of the eyelids and covering the sclera (conjunctiva) is inflamed.
Symptom
1. Itchy, red blurry eyes
2. Eye discharge
3. Feeling like something is in the eyes
4. Photophobia
5. Swelling of the eyes
6. Burning eyes
Cause/Types
Conjunctivitis can be caused by a number of reasons. They are bacteria, fungi, viruses and allergies. We have talked about infectious conjunctivitis before which you can read up here. Let us look at allergic conjunctivitis.
Allergic conjunctivitis affects people suffering from seasonal allergies. This happens when they are exposed to a trigger. Chemical conjunctivitis spreads as a result of exposure to noxious chemicals like chlorine in swimming pools or even air pollutants.
Pharmacotherapy/Treatment
Avoiding irritants is the first line of action. For chemical irritants, wash the eyes immediately. Artificial tears and cold compress can help. The use of antihistamine and non steroidal antiinflammatory drugs (NSAIDs) oral or topical is recommended when it is itchy and inflamed. Topical steroids can also be used.
Retina Detachment
When the retina is torn, it is detached from the tissues holding it. This can lead to vision loss.
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| Retina detachment Mayoclinic |
Types
Rhegmatogenous: this is the most common. A small break or tear appears within the retina resulting in flow of the fluid underneath the retina, eventually separating it from the retina pigment epithelium.
Tractional: in this type, the retina detaches due to the contraction of the scar tissue on the surface of the retina resulting in separation. This is not very common.
Exudative (serous): this happens due to eye injury/trauma, inflammatory disorders and other such retina diseases. In this type, the retina suffers no tears or breaks despite the fluid leaking and reattach it.
Symptoms
1. Presence of retain light shadows through field of vision
2. Sudden appearance of light flashes in one of both eyes
3. Blurred vision
4. Steadily losing phepheral or side vision
5. Sudden appearance of floaters (tiny specks drifting through eye field) of the affected eyes.
Pharmacotherapy/Treatment
Cryopexy (freeze) or laser surgery: this is a situation whereby tiny burns are made around the damage area to weld the retina back to place. Thereafter, cryopexy is used to freeze the area around the weld helping to detach the retina.
Vitrectomy: this procedure may be performed in some cases. This is the incision of tiny holes in the white eye to drain the vitreous humour by means of a special instrument and injecting gas into the eye to push the retina back to its appropriate position.
Eye Strain
When the eye gets tired from intense use, it gets strained. Examples of activities that strain the eyes are watching television for a long time or sitting in front of a computer monitor all day long. It does not lead to permanent eye damage.
Symptoms
1. Watery, itchy and dry eyes
2. Headache
3. Blurred or double vision
4. Photophobia
5. Soreness
6. Difficulty keeping the eyes open
Pharmacotherapy/Treatment
Resting the eyes, improving lighting conditions in the house and the use of artificial tears solve the problem.
Night Blindness (Nyctalopia)
It is a condition characterized by difficulty in seeing at night or in a dim environment. It is likely a symptom of other eye conditions.
Cause
1. Cataract
2. Nearsightedness
3. Vitamin A deficiency
Pharmacotherapy/Treatment
Treat the underlying cause and give vitamin A supplement
Colour Blindness
When the pigment in the eye cones have a problem, they have difficulty in recognising some specific colours. There are three types of colour blindness. They are red-green which is more common and blue-yellow. Another is monochromatic colour blindness in which everything appear as white and black. But this condition is rare.
When a person cannot differentiate betweenel red and green, it is said to be red-green colour blind. When it is blue and yellow that cannot be differentiated, it is blue-yellow colour blind.
Colour blindness is genetic and more common in men. It affects the wavelength and makes it difficult to differentiate colours or cones or shades of some colours.
Symptoms
Symptoms re not able to differentiate between some shades of colours. It begins from childhood and it is only notices when it is difficult to differentiate between colours in class or in adulthood differentiating colours in traffic lights. Defects can be mild, moderate to severe
Causes
1. Family history
2. Certain drugs
3. Certain eye disease
Pharmacotherapy/Treatment
No reliable treatment. Contact lenses or glasses with filters are available.
Eye Floaters
This is a situation whereby strings, black/gray specks, or cobweb shapes appear in the vision moving along with the eyes. They disappear in an attempt to view through them. They are like spots in vision. They appear like an insect in your phone camera lens that appear like a shadow image in a photograph. Another illustration that fits it is like the frequent bursts or streaks of lights that appear like stars when you take a punch in the head.
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They are mostly produced due to age related changes in the vitreous humour turning into more and more liquid. Originally, the vitreous humour is a mesh of fibrous tissue microscopic in nature. But when the vitreous clumps always, they form macroscopic networks that form a shadow in the eyes.
It rarely gets serious but it can be serious when it appears more frequently.
Cause
1. Symptoms of retinal detachment
2. Migraine
3. Trauma to the eye causes the clumps to move resulting in eye flashes.
Symptoms
Appearance of dark specks or transparent strings floating around within the vision appear like distant objects. The object moves along with the direction of the eyes. The object quickly disappears when the eye is focused on it.
Pharmacotherapy/Treatment
Vitrectomy
Proptosis (Exophthalmos)
This is the protrusion of the eyeball. It can affect one or both eyes. Space taking lesions such as swelling of the fats or muscles or tissue behind the eyes expose more area of the eyeball to air. This causes dryness.
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| Proptosis Wiki |
Symptoms
1. Eye pain and irritation
2. Photophobia
3. Blurry vision
4. Eye secretion (lacrimation)
5. Diplopia (double vision resulting from weakened eye muscle)
6. Vision loss due to pressure on the optical nerves
Cause
The major cause is grave disease. Other reasons are orbital mass or inflammation, thrombosis of cavernous sinus, fistulas or expansion of the orbital bones.
1. Thyroid disease
2. Orbital congestion due to orbital pseudotumor inflammatory
3. Cavernous sinus caused by arteriovenous fistula
Pharmacotherapy/Treatment
Lubrication using eye tears eye drop is to ease symptoms. Systemic corticosteroids are used when it is caused by orbital congestion or thyroid disease. Selective embolization works best in case of cavernous fistulas.
Keratoconus
This eye disease presents with an irregularly shaped cornea which prevents light from focusing correctly on the retina. Cornea becomes thin and more cone shaped causing blurred vision and sensitivity to the bright lights.
Cause
There is no known cause. Although, hereditary, allergies, eye trauma and pre existing conditions are under the radar. It is a disease that affects youth especially beginning from late teens to early twenty. It may last for several years.
Symptoms
Begins with a slight blurred or distorted vision that gets worse with time requiring frequent changing eye glasses. Other symptoms soon follow such as glare and ghost image (appearance of several images of same objects when looking at one).
Diagnosis
Slit lamp or corneal topography
Pharmacotherapy/Treatment
1. Contact Len: Custom soft, gas permeable, scleral contact lens
2. Eyeglasses
3. Corneal cross linking (CCL): the use of ultraviolet light to soften the corneal. Eyedrops to prevent inflammation and infection.
4. Surgery: this is the last option. Laser surgery is not recommended.
Eyelid Twitching (Myokymia)
This is a common eye disorder that affects everybody at one point in life. It becomes a condition of interest when it becomes too frequent and interferes with daily activities. It can be uncomfortable.
It is a situation whereby there is involuntary muscle movement of the eyelid. Extreme cases called blepharospasm is a situation whereby the eye is forced to close for some seconds to reduce the twitching.
Cause
1. Stress, fatigue, lack of sleep and tiredness
2. Alcohol, caffeine
3. Side effects of some drugs
4. Eye strains
5. Irritants
6. Benign essential blepharospasm is caused by nerve impulses
Causes of serious eye twitching
1. Blepharitis
2. Conjunctivitis
3. Dry eyes
4. Brain and nervous disorders
5. Bell's palsy (facial palsy)
6. Dystonia
7. Cervical dystonia (spasmodic torticollis)
8. Multiple sclerosis
9. Parkinson disease
10. Tourette syndrome
11. Undiagnosed corneal scratches
Symptoms
1. Excessive blinking
2. Eye irritation
3. Fatigue
4. Photophobia
5. Tension
6. Involuntary muscle movement around the eyes
Pharmacotherapy/Treatment
1. Reduce stress, sleep well, avoid caffeine and alcohol.
2. Surgery (myectomy) to remove muscles and nerves causing it.
3. Facial injections (botulinum toxin) works for few months
4. Artificial tears and warm compress
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