A
Amblyopia: Vision is reduced (even with glasses) because the optic nerve has not
fully developed.
Prevention: If you were prescribed glasses, wear them until at least 14 years of age to
make sure that your optic nerves develop completely.
Ametropia: Blurriness due to either myopia, hyperopia (also know as hypermetropia)
or astigmatism.
Prevention: eHow Article
Anti-Oxidants: Help promote a healthy retina, macula and lens and prevent macular
degeneration and cataracts.
Arcus Senilus: Blue ring in the peripheral cornea that makes it look like the iris is
turning grayish blue.
Tip: Arcus Senilus is considered to be normal in the elderly. If present in a younger
eye, it could suggest high levels of cholesterol.
Astigmatism: Distortion (blurriness) caused by a cornea shaped like a football.
Prevention: eHow Article
B
Bifocal Glasses: Lenses with two different prescriptions.
The upper part of the lens is to see far, the lower part is for near.
Tip: Bifocal lenses are not recommended when using a computer, because no part of
the lens is allowing you to see intermediate distance.
Tip: Bifocal and trifocal glasses have lines running across the lens. Therefore, they
are not the best options if you value aesthetics.
Binocular Indirect Ophthalmoscope (B.I.O.): Instrument used to look at the
peripheral retina.
Biomicroscope (also known as the Slit Lamp): Instrument used to look at the front
portion of the eye, specifically the cornea, conjunctiva, sclera, aqueous, iris and lens.
C
Cataract: The lens becomes opaque (cloudy) and vision is blurry even with brand
new glasses. Cataracts must be surgically removed to restore vision. These days a
good surgeon can perform this surgery within 15 minutes.
Prevention: Ultraviolet light from the sun causes cataract formation. Wear sunglasses
with 100% UV protection while outside during daytime. See this eHow Article for more
information.
Conjunctivitis: Infection of the conjunctiva.
Prevention: To lower your risk of getting an eye infection, rub your contact lenses,
even if it says 'No Rub' on the bottle.
Prevention: At night, remove your contacts one to two hours before going to sleep.
Prevention: In the morning, wait a few minutes before inserting your contact lenses.
Prevention: Do not stretch the recommended contact lens wear schedule. (Do not
wear monthly disposables for two months).
Prevention: Do not sleep with contact lenses on.
Cycloplegia: Paralysis of the ciliary muscle.
The ciliary body pulls on the lens to make the eye focus. See an illustration.
The lens is the part of the eye responsible for focusing. See an illustration.
D
Dilation (also known as Pupillary Dilation): To view the whole retina, medications
are instilled in the eye to get the pupil wide open.
Diopter: Unit of measurement of power (strength) of lenses.
Usually omitted on prescriptions. Example -2.25 is -2.25 diopters.
Diplopia: Double vision.
Tip: Must go to the eye doctor immediately if of recent onset. Might indicate a very
serious condition.
Dry Eyes: Eyes are dry, due to lack of tear production and/or tears being unstable
(evaporating too fast).
Product: Artificial tears: provides instant relief, but only lasts a few minutes and must
be reused all the time to be effective.
Product: Liquid gel: lasts longer than artificial tears. Better choice for mild to moderate
dry eyes. Still have to use many times a day.
Product: Gel: lasts even longer, but will blur your vision for a few minutes.
Product: Ointment: lasts the longest, but will definitely blur your vision for a while. Best
used at nighttime, right before going to sleep.
Product: Omega-3 capsules: taken by mouth, they help your eyes produce more
stable tears.
Tip: Must allow 2-3 weeks before noticing results with Omega-3 capsules.
Treatment: Punctal plugs: plug the punctum (where tears exit the eye) resulting in
more tears staying in the eye.
More info about dry eyes in Tip #6 of the Blog.
E
Emmetropia: Absence of Ametropia.
No myopia (nearsightedness), no hyperopia (hypermetropia or farsightedness) and no
astigmatism.
F
Farsightedness (also known as Hyperopia or Hypermetropia): Can see far, near
is blurry. Caused by a cornea too flat, an eyeball too short, or both.
Floaters: Particles swimming inside the vitreous (Clear gel filling the inside of the
eye). Seen as gray or black lines or dots by the person who has them.
Tip: Flashes of lights and/or a lot more floaters than usual could indicate a retinal
detachment in progress. See your eye doctor right away.
G
Glaucoma: Eye disease affecting the optic nerve, resulting in loss of peripheral (side)
vision.
H
Heterochromia: Both eyes (iris) are not the same color.
Hypermetropia (also known as Farsightedness): See below.
Hyperopia (also known as Farsightedness): Can see far, near is blurry. Caused by
a cornea too flat, an eyeball too short, or both.
K
Keratoconus: Thinning of the cornea causing it to distort, which results in blurry
vision.
Tip: Rigid gas permeable (hard) contact lenses must be worn to improve vision in
patients with moderate keratoconus.
Tip: If the keratoconus keeps progressing, contact lenses will not work anymore.
Corneal transplant must then be performed.
Keratometer: Instrument which measures the curvature of the cornea. For contact
lens fitting
Tip: If the contact lens is much steeper than the cornea, it will suffocate it, elevating
the risk for infection.
Tip: If the contact lens is much flatter than the cornea, it will move excessively and
cause discomfort.
L
Legally Blind: Vision of the best eye is 20/200 or worse, or peripheral of the best eye
is 20 degrees or less.
M
Macular Degeneration: Disease affecting the macula. Central vision is lost.
Prevention: Quit smoking, wear sunglasses to protect your eyes from the sun's
harmful ultraviolet rays. Read this eHow Article for more information.
Monovision: One eye is corrected for distance vision, while the other eye is set for
near vision. Achieved by surgery or with contact lenses.
Tip: Monovision will reduce stereopsis drastically and peripheral vision to a certain
extent.
Tip: Consider getting multifocal contact lenses or reading glasses instead.
Multifocal Contact Lenses: Contacts for presbyopia.
Multifocal Toric Contact Lenses: Contacts for astigmatism and presbyopia.
Myopia (also know as Nearsightedness): Can see near, far is blurry. Caused by a
cornea too steep, an eyeball too long, or both.
Prevention: eHow Article
N
Nearsightedness (also know as Myopia): Can see near, far is blurry. Caused by a
cornea too steep, an eyeball too long, or both.
Prevention: eHow Article
Nystagmus: Eyes move very rapidly from side to side.
Vision is poor. Usually due to a macular disease.
O
Ophthalmologist: Medical doctor specializing in eyes. Can perform surgery and
prescribe any medication. Can also prescribe glasses and contacts.
Ophthalmoscope: Instrument used to look at the back of the eye. More specifically
the retina, the macula and the optic nerve.
Optical Center (O.C.): portion of the lens that is right if front of the center of the pupil,
when the person looks straight ahead.
Optician: Assists in selecting, adjusting and dispensing glasses. Also measures the O.
C., the segment height and the P.D.
Optometrist: Eye doctor that can prescribe glasses, contacts and select medication,
but cannot perform surgery.
P
Peripheral Vision: Side vision.
Polycarbonate Lenses: Used for safety glasses, because it is very impact-resistant.
Polycarbonate lenses do not break as easily as plastic lenses.
Tip: Polycarbonate lenses are a must for those who can only see out of one eye.
Tip: Polycarbonate is highly recommended for kids and people with high-risk
occupations, such as police officers.
Tip: polycarbonate lenses are thinner than plastic lenses. However, plastic lenses
feature less distortion than polycarbonate lenses.
Progressive Glasses: Lenses allowing you to see at all distances.
Upper lens for far, middle for intermediate, lower for near.
Tip: Unlike bifocal and trifocal glasses, there are no lines in progressives lenses.
Presbyopia: Near is blurry. The muscle isn't pulling enough on the lens to focus.
Pterygium: The sclera grows over the cornea , due to too much exposure to UV.
Prevention: Wear sunglasses to protect your eyes from the UV rays and prevent
pterygium. Sunglasses guidelines: eHow Article.
Pupillary Distance (P.D.): Distance between the two pupils.
Tip: Distortion, blurriness, dizziness and/or double vision can occur if the lenses of
your glasses are not centered with the pupillary distance.
R
Retinal Detachment: The retina is ripped off its original location. Serious condition
that can lead to blindness if left untreated.
Tip: Flashes of lights and/or a lot more floaters than usual could indicate a retinal
detachment in progress. See your eye doctor right away.
Definition. Floaters: Particles swimming inside the vitreous (Clear gel filling the inside
of the eye). Seen as gray or black lines or dots by the person who has them.
Retinopathy: Retinal disease which can lead to blindness.
Usually caused by diabetes or blood pressure.
Prevention: Some retinopathies can usually be prevented by controlling diseases
such as diabetes and high blood pressure.
S
Segment Height: The vertical location where the bifocal (or trifocal or progressive) is
located in the lens.
Stereopsis: Depth perception.
Strabismus: Crossed eye. Also known as lazy eye. One eye is either turned inward
or outward.
Supplements: Help promote good eye health and vision.
Stye: Bump on an eyelid. Usually due to a clogged gland.
Prevention: Avoid applying eyeliner inside the lash line. It could clog the openings of
the glands.
T
Tonometer (also known as "the glaucoma test”): Instrument that measures the intra-
ocular pressure (IOP). If the IOP is too high, it can lead to glaucoma.
Toric Contact Lenses: Contacts for astigmatism.
Transitions Lenses: Lenses that darken when exposed to ultraviolet.
Clear lenses inside that turn into sunglasses outside.
Tip: Since Transitions need UV to darken, and that windows block a good portion of
UV, these lenses do not get very dark when inside a car.
Trifocal Glasses: Lenses with 3 different prescriptions.
Upper lens to see far, middle is for intermediate, lower is for near.
Tip: Bifocal and trifocal glasses have lines running across the lens. Therefore, they
are not the best options if you value aesthetics.
20/20 Vision: Normal vision.
20/40 Vision: Two times worse than 20/20. Someone with 20/40 vision must stand
within 20 feet to see something that can be seen at 40 feet by someone with 20/20
vision.
V
Visual Field: Instrument to test your peripheral (side) vision. Consists of clicking a
button every time a light is seen.
Amblyopia: Vision is reduced (even with glasses) because the optic nerve has not
fully developed.
Prevention: If you were prescribed glasses, wear them until at least 14 years of age to
make sure that your optic nerves develop completely.
Ametropia: Blurriness due to either myopia, hyperopia (also know as hypermetropia)
or astigmatism.
Prevention: eHow Article
Anti-Oxidants: Help promote a healthy retina, macula and lens and prevent macular
degeneration and cataracts.
Arcus Senilus: Blue ring in the peripheral cornea that makes it look like the iris is
turning grayish blue.
Tip: Arcus Senilus is considered to be normal in the elderly. If present in a younger
eye, it could suggest high levels of cholesterol.
Astigmatism: Distortion (blurriness) caused by a cornea shaped like a football.
Prevention: eHow Article
B
Bifocal Glasses: Lenses with two different prescriptions.
The upper part of the lens is to see far, the lower part is for near.
Tip: Bifocal lenses are not recommended when using a computer, because no part of
the lens is allowing you to see intermediate distance.
Tip: Bifocal and trifocal glasses have lines running across the lens. Therefore, they
are not the best options if you value aesthetics.
Binocular Indirect Ophthalmoscope (B.I.O.): Instrument used to look at the
peripheral retina.
Biomicroscope (also known as the Slit Lamp): Instrument used to look at the front
portion of the eye, specifically the cornea, conjunctiva, sclera, aqueous, iris and lens.
C
Cataract: The lens becomes opaque (cloudy) and vision is blurry even with brand
new glasses. Cataracts must be surgically removed to restore vision. These days a
good surgeon can perform this surgery within 15 minutes.
Prevention: Ultraviolet light from the sun causes cataract formation. Wear sunglasses
with 100% UV protection while outside during daytime. See this eHow Article for more
information.
Conjunctivitis: Infection of the conjunctiva.
Prevention: To lower your risk of getting an eye infection, rub your contact lenses,
even if it says 'No Rub' on the bottle.
Prevention: At night, remove your contacts one to two hours before going to sleep.
Prevention: In the morning, wait a few minutes before inserting your contact lenses.
Prevention: Do not stretch the recommended contact lens wear schedule. (Do not
wear monthly disposables for two months).
Prevention: Do not sleep with contact lenses on.
Cycloplegia: Paralysis of the ciliary muscle.
The ciliary body pulls on the lens to make the eye focus. See an illustration.
The lens is the part of the eye responsible for focusing. See an illustration.
D
Dilation (also known as Pupillary Dilation): To view the whole retina, medications
are instilled in the eye to get the pupil wide open.
Diopter: Unit of measurement of power (strength) of lenses.
Usually omitted on prescriptions. Example -2.25 is -2.25 diopters.
Diplopia: Double vision.
Tip: Must go to the eye doctor immediately if of recent onset. Might indicate a very
serious condition.
Dry Eyes: Eyes are dry, due to lack of tear production and/or tears being unstable
(evaporating too fast).
Product: Artificial tears: provides instant relief, but only lasts a few minutes and must
be reused all the time to be effective.
Product: Liquid gel: lasts longer than artificial tears. Better choice for mild to moderate
dry eyes. Still have to use many times a day.
Product: Gel: lasts even longer, but will blur your vision for a few minutes.
Product: Ointment: lasts the longest, but will definitely blur your vision for a while. Best
used at nighttime, right before going to sleep.
Product: Omega-3 capsules: taken by mouth, they help your eyes produce more
stable tears.
Tip: Must allow 2-3 weeks before noticing results with Omega-3 capsules.
Treatment: Punctal plugs: plug the punctum (where tears exit the eye) resulting in
more tears staying in the eye.
More info about dry eyes in Tip #6 of the Blog.
E
Emmetropia: Absence of Ametropia.
No myopia (nearsightedness), no hyperopia (hypermetropia or farsightedness) and no
astigmatism.
F
Farsightedness (also known as Hyperopia or Hypermetropia): Can see far, near
is blurry. Caused by a cornea too flat, an eyeball too short, or both.
Floaters: Particles swimming inside the vitreous (Clear gel filling the inside of the
eye). Seen as gray or black lines or dots by the person who has them.
Tip: Flashes of lights and/or a lot more floaters than usual could indicate a retinal
detachment in progress. See your eye doctor right away.
G
Glaucoma: Eye disease affecting the optic nerve, resulting in loss of peripheral (side)
vision.
H
Heterochromia: Both eyes (iris) are not the same color.
Hypermetropia (also known as Farsightedness): See below.
Hyperopia (also known as Farsightedness): Can see far, near is blurry. Caused by
a cornea too flat, an eyeball too short, or both.
K
Keratoconus: Thinning of the cornea causing it to distort, which results in blurry
vision.
Tip: Rigid gas permeable (hard) contact lenses must be worn to improve vision in
patients with moderate keratoconus.
Tip: If the keratoconus keeps progressing, contact lenses will not work anymore.
Corneal transplant must then be performed.
Keratometer: Instrument which measures the curvature of the cornea. For contact
lens fitting
Tip: If the contact lens is much steeper than the cornea, it will suffocate it, elevating
the risk for infection.
Tip: If the contact lens is much flatter than the cornea, it will move excessively and
cause discomfort.
L
Legally Blind: Vision of the best eye is 20/200 or worse, or peripheral of the best eye
is 20 degrees or less.
M
Macular Degeneration: Disease affecting the macula. Central vision is lost.
Prevention: Quit smoking, wear sunglasses to protect your eyes from the sun's
harmful ultraviolet rays. Read this eHow Article for more information.
Monovision: One eye is corrected for distance vision, while the other eye is set for
near vision. Achieved by surgery or with contact lenses.
Tip: Monovision will reduce stereopsis drastically and peripheral vision to a certain
extent.
Tip: Consider getting multifocal contact lenses or reading glasses instead.
Multifocal Contact Lenses: Contacts for presbyopia.
Multifocal Toric Contact Lenses: Contacts for astigmatism and presbyopia.
Myopia (also know as Nearsightedness): Can see near, far is blurry. Caused by a
cornea too steep, an eyeball too long, or both.
Prevention: eHow Article
N
Nearsightedness (also know as Myopia): Can see near, far is blurry. Caused by a
cornea too steep, an eyeball too long, or both.
Prevention: eHow Article
Nystagmus: Eyes move very rapidly from side to side.
Vision is poor. Usually due to a macular disease.
O
Ophthalmologist: Medical doctor specializing in eyes. Can perform surgery and
prescribe any medication. Can also prescribe glasses and contacts.
Ophthalmoscope: Instrument used to look at the back of the eye. More specifically
the retina, the macula and the optic nerve.
Optical Center (O.C.): portion of the lens that is right if front of the center of the pupil,
when the person looks straight ahead.
Optician: Assists in selecting, adjusting and dispensing glasses. Also measures the O.
C., the segment height and the P.D.
Optometrist: Eye doctor that can prescribe glasses, contacts and select medication,
but cannot perform surgery.
P
Peripheral Vision: Side vision.
Polycarbonate Lenses: Used for safety glasses, because it is very impact-resistant.
Polycarbonate lenses do not break as easily as plastic lenses.
Tip: Polycarbonate lenses are a must for those who can only see out of one eye.
Tip: Polycarbonate is highly recommended for kids and people with high-risk
occupations, such as police officers.
Tip: polycarbonate lenses are thinner than plastic lenses. However, plastic lenses
feature less distortion than polycarbonate lenses.
Progressive Glasses: Lenses allowing you to see at all distances.
Upper lens for far, middle for intermediate, lower for near.
Tip: Unlike bifocal and trifocal glasses, there are no lines in progressives lenses.
Presbyopia: Near is blurry. The muscle isn't pulling enough on the lens to focus.
Pterygium: The sclera grows over the cornea , due to too much exposure to UV.
Prevention: Wear sunglasses to protect your eyes from the UV rays and prevent
pterygium. Sunglasses guidelines: eHow Article.
Pupillary Distance (P.D.): Distance between the two pupils.
Tip: Distortion, blurriness, dizziness and/or double vision can occur if the lenses of
your glasses are not centered with the pupillary distance.
R
Retinal Detachment: The retina is ripped off its original location. Serious condition
that can lead to blindness if left untreated.
Tip: Flashes of lights and/or a lot more floaters than usual could indicate a retinal
detachment in progress. See your eye doctor right away.
Definition. Floaters: Particles swimming inside the vitreous (Clear gel filling the inside
of the eye). Seen as gray or black lines or dots by the person who has them.
Retinopathy: Retinal disease which can lead to blindness.
Usually caused by diabetes or blood pressure.
Prevention: Some retinopathies can usually be prevented by controlling diseases
such as diabetes and high blood pressure.
S
Segment Height: The vertical location where the bifocal (or trifocal or progressive) is
located in the lens.
Stereopsis: Depth perception.
Strabismus: Crossed eye. Also known as lazy eye. One eye is either turned inward
or outward.
Supplements: Help promote good eye health and vision.
Stye: Bump on an eyelid. Usually due to a clogged gland.
Prevention: Avoid applying eyeliner inside the lash line. It could clog the openings of
the glands.
T
Tonometer (also known as "the glaucoma test”): Instrument that measures the intra-
ocular pressure (IOP). If the IOP is too high, it can lead to glaucoma.
Toric Contact Lenses: Contacts for astigmatism.
Transitions Lenses: Lenses that darken when exposed to ultraviolet.
Clear lenses inside that turn into sunglasses outside.
Tip: Since Transitions need UV to darken, and that windows block a good portion of
UV, these lenses do not get very dark when inside a car.
Trifocal Glasses: Lenses with 3 different prescriptions.
Upper lens to see far, middle is for intermediate, lower is for near.
Tip: Bifocal and trifocal glasses have lines running across the lens. Therefore, they
are not the best options if you value aesthetics.
20/20 Vision: Normal vision.
20/40 Vision: Two times worse than 20/20. Someone with 20/40 vision must stand
within 20 feet to see something that can be seen at 40 feet by someone with 20/20
vision.
V
Visual Field: Instrument to test your peripheral (side) vision. Consists of clicking a
button every time a light is seen.
Glossary
