Eye Conditions

EYE CONDITIONS &
GLOSSARY OF EYE CARE TERMS

A -B - C - D - E - F - G - H - I - J - K - L
M - N - O - P - Q- R - S - T - U - V - W - X - Y - Z

Aberration – The failure of a refracting surface or lens to produce an exact point-to-point correspondence between an object and its image.

Ablation – Removal of all or part of an object, usually from the surface inward.

Accommodation – Adjustment by the eye for seeing at different distances, accomplished by changing the shape of the crystalline lens through action of the ciliary muscle.

Adnexa:  The tissues and structures surrounding the eye eyelids, orbit, extraocular muscles, and lacrimal system.

Age-Related Macular Degeneration ARMD
Age-related macular degeneration (ARMD) is a degenerative condition of the macula (the central retina).

Amblyopia
Amblyopia is a term used to describe an uncorrectable loss of vision in an eye that appears to be normal. It’s commonly referred to as “lazy eye” and can occur for a variety of reasons. Amblyopia– Decreased visual acuity without any apparent disease of the eye.

Ametropia – Any optical error of the eye that can be corrected by glasses or contact lenses.  See Refractive error.

Anterior Chamber – The area between the inner-most layer of the cornea and the iris.

Anterior Chamber Angle – The junction of the cornea and the iris.

Anterior Segment – Front portions of the eye including the cornea, the anterior chamber, the iris, and the crystalline lens.

Aphakia – Absence of the crystalline lens of the eye, usually as a result of cataract surgery.

Aqueous Humor – Clear watery fluid, which fills the anterior chamber of the eye.

Artery Occlusion
A retinal artery occlusion occurs when the central retinal artery or one of the arteries that
branch off of it becomes blocked.

Astigmatic Keratotomy (AK) – Surgical procedure where incisions are made in the cornea to correct astigmatism.

Astigmatism
Astigmatism means that the cornea is oval like a football instead of spherical like a basketball. Most astigmatic corneas have two curves – a steeper curve and a flatter curve. Astigmatism – Distortions in the cornea, or sometimes the lens, that focus light rays at different lengths, making it difficult to focus at any distance well.

Automated Lamellar Keratoplasty (ALK) – A surgical procedure for correcting high myopia by removing and folding back a layer of the anterior cornea, removing a precise amount of corneal tissue with an automated microkeratome, and folding back into position the first layer without stitches.

Autorefraction – An automated objective refraction that measures each eye individually without patient response or interaction.

Axis – An axis is a line dividing a regular figure symmetrically.  As used in optometry. Two axes define the direction of the longest and shortest radii of an oval (astigmatic) lens system of the eye.  Common usage refers to the longer axis of a lens, the direction of least power, as the cylinder axis. top

B

Basal Cell Carcinoma
Basal cell carcinoma is a type of skin cancer that occurs most commonly on the face or neck, often near an eyelid or on the nose.

Best Corrected Visual Acuity (BCVA) – T he best vision the patient can achieve when they are using the most updated prescription.

Bifocal – A lens with two optical zones, one for near vision and one for distance vision.

Bilateral – Relating to or affecting both right and left eye.

Binocular Vision – The ability to use both eyes simultaneously to focus on the same object and to fuse the images from both eyes into a single image.

Biometry – Either ultrasound or laser light used to measure the length of the eye to calculate power needed for IOL placement.

Biomicroscope – See Slip lamp.

Blepharitis
Blepharitis is a common inflammatory condition that affects the eyelids.

Blepharoplasty – Blepharoplasty is the surgical technique used to remove excessive skin from the eyelids. Sometimes referred to as an Eyelid Lift.

Blindness – Having central visual acuity of 20/200 or less in the better eye after correction; or having visual acuity of better than 20/200, but having a field of vision of no greater than 20 degrees (legal definition).
                                
Branch Retinal Artery Occlusion
A retinal artery occlusion occurs when the central retinal artery or one of the arteries that
branch off of it becomes blocked.

Branch Retinal Vein Occlusion
Retinal vein occlusion occurs when the circulation of a retinal vein becomes obstructed by an adjacent blood vessel, causing hemorrhages in the retina.

Bulbar Conjunctiva – The portion of the conjunctiva that covers the outer surface of the globe (eyeball). top

C

Canaliculus (canaliculi) – Tubes connecting the eye to the lacrimal sac.  The puncta are the openings of the canaliculi.

Canthus – The angle formed by the meeting of the upper and lower eyelids, specified as outer of temporal, and inner or medical (nasal).

Capsular Tension Ring – PMMA ring inserted into capsular bag to stabilize capsule to withstand the pressures of cataract surgery.

Cataract
A cataract is a clouding of the natural lens, the part of the eye responsible for focusing light and producing clear, sharp images.

Cataract – Opacity or clouding of the natural crystalline lens, causing foggy vision.  Symptoms may include necessity of more light to read, more difficulty driving at night due to glare from headlights, or loss of contrast sensitivity.

Cellophane Retinopathy
Epi-retinal membrane (ERM) or macular pucker is a cellophane-like membrane that forms over the macula.

Central Retinal Vein Occlusion
Retinal vein occlusion occurs when the circulation of a retinal vein becomes obstructed by an adjacent blood vessel, causing hemorrhages in the retina.

Central Serous Chorioretinopathy
Central serous chorioretinopathy (CSCR) is a problem that affects the macula (central portion of the retina).

Chalazion
A chalazion (stye) is a small lump in the eyelid caused by obstruction of an oil producing or meibomian gland.

Choroid – Continuation of the ciliary body in the form of a layer of tissue that lies between the sclera and the retina, which furnishes nourishment to the other parts of the eyeball.

Choroidal Neovascular Membrane
Choroidal neovascular membrane (CNVM) is a problem that is related to a wide variety of retinal diseases, but is most commonly linked to age-related macular degeneration.

Choroidal Nevus
A nevus is typically a flat, benign, pigmented area that may appear inside the eye or on its surface.

Cilia – Technical term for eyelashes.

Ciliary Body – Band-like structure of muscle and secretory tissue that extends from the edge of the iris and encircles the inside of the sclera toward the front of the eye.

Ciliary Muscle – Muscle fibers in the ciliary body.

Ciliary Processes – Inner surface of the ciliary body that is arranged in folds, rows or ridges.  This structure secretes the aqueous humor.

Cogan's Dystrophy
Cogan's Dystrophy is a disease that affects the cornea. It is commonly called Map-Dot-Fingerprint Dystrophy because of microscopic dot and fingerprint-like patterns that form within the layers of the cornea.

Collagen – A protein found in connective tissues which is relative inelastic but has high tensile strength.

Color Blindness
Color blindness may be a hereditary condition or caused by disease of the optic nerve or retina.

Computer Vision Syndrome (CVS)
Computer vision syndrome (CVS) is a term that describes eye-related problems and the other symptoms caused by prolonged computer use.

Computerized Corneal Topography (CCT) – Measurement to map exact areas and degree of corneal astigmatism.

Concave Lens – A lens having a surface that is rounded inward, to produce focal power that diverges paralle! rays of light.  Also called a diverging, myopic, or minus lens, denoted by the minus sign.

Cone – One of the two types of light-sensitive cells in the eye.  Cone cells are concentrated in the center of the retina and are responsible for color vision.

Congenital – Present at birth.

Conjunctiva – Thin, translucent layers of mucous membrane, which lines the eyelids and covers the front part of the eyeball, excluding the cornea.

Conjunctivitis
Conjunctivitis, commonly known as pink eye, is an infection of the conjunctiva (the outer-most layer of the eye that covers the sclera).
Conjunctivitis – Inflammation of the conjunctiva, commonly called “pink eye”.

Contact Lens – A lens constructed to fit directly on the eyeball.

Contrast Sensitivity – A measurement, which determines the ability of the observer to see a wide range of everyday objects under normal and reduced illumination conditions.

Convergence – The process in which the visual axes of the two eyes are directed toward the same near point, with the result that the eyes are turned inward.
Convex Lens – A lens having a surface that is curved outward to produce focal power that converges parallel rays of light to a focus.  Also called a converging, hyperopic, or plus lens, denoted by the plus sign.

Cornea – Referred to as the “window of the eye”.  It provides most of the focusing power when light enters the eye.  The cornea is composed of 5 layers of tissue.  T he outer layer (the epithelium) is the eye’s protective layer.  This layer is made up of highly regenerative cells that have the ability to grow back within three days.  You generate a completely new epithelial layer every five days.  This allows for fast healing of superficial injuries to the cornea.  Most of the inner layers provide strength to the eye.

Corneal Dystrophy
Fuchs’ dystrophy is an inherited condition that affects the delicate inner layer (endothelium) of the cornea.

Corneal Ulcer
A corneal ulcer forms when the surface of the cornea is damaged or compromised.

Crystalline Lens – A transparent lens suspended inside the eye immediately behind the iris, which brings rays of light to a focus on the retina.

Cyclindrical Lens – See Toric lens.

Cycloplegic – A drug that temporarily puts the ciliary muscle at rest and dilates the pupil, often used to ascertain the error of refraction.  Administered in the form of drops.  See Cycloplegic refraction.

Cycloplegic Refraction – A subjective refraction performed after instillation of cycloplegic drops.  The cycloplegic drops temporarily prevent the muscular accommodation of the eye and permit a more objective evaluation of the refractive error of the eye.

Cystoid Macular Edema
Cystoid macular edema (CME), or swelling of the macula, typically occurs as a result of disease, injury or more rarely, eye surgery.

Cytomegalovirus
The cytomegalovirus (CMV) is related to the herpes virus and is present in almost everyone. top

D

Dacryocystitis
Dacryocystitis is an infection of the tear sac that lies between the inner corner of the eyelids and the nose.

Depth Perception – The ability to perceive the relative position of objects in space.  See Stereoscopic vision.

Diabetic Retinopathy
Patients with diabetes are more likely to develop eye problems such as cataracts and glaucoma, but the disease’s affect on the retina is the main threat to vision.

Dilate – To spread wide, enlarge, or expand.  In eye care, dilation describes the degree of opening of the pupil.  The pupil can be further dilated by the instillation of cycloplegic drops.

Diopter – A unit of measurement of strength or refractive power of lenses.  Can also refer to the relative curvature of a lens surface.

Droopy Eyelids
Ptosis (pronounced toe' sis), or drooping of the upper eyelid, may occur for several reasons such
as: disease, injury, birth defect, previous eye surgery and age.

Dry Eyes
Dry eye syndrome is one of the most common problems treated by eye physicians. top

E

Ectropion
Patients with ectropion have a sagging lower eyelid that leaves the eye exposed and dry.

Emmetropia – The focal condition of the normal eye in which there is no refractive error.]

Endocyclophotocoagulation (ECP) – A laser attached to a camera used to ablate ciliary processes to reduce pressure inside the eye by decreasing aqueous production.

Entropion
Entropion, an eyelid that turns inward, is a problem that typically affects the lower lid.

Epi-retinal membrane
Epi-retinal membrane (ERM) or macular pucker is a cellophane-like membrane that forms over the macula.

Episcleritis
Episcleritis is an inflammatory condition of the connective tissue between the conjunctiva and sclera known as the episclera.

Epithelium – A clear outer protective coating that covers the cornea, conjunctiva, and inner eyelid.

Esophoria – A tendency of an eye to turn inward when covered.

Esotropia – A condition in which one or both eyes turn too far inward, sometimes called convergent strabismus or crossed eyes.

Exophoria – A tendency of an eye to turn outward when covered.

Exophthalmos – An abnormal protrusion of the eyeball.

Exotropia – A condition in which one or both eyes turn too far outward, sometimes called divergent strabismus.

Extraocular Muscles – External muscles attached to the outside of the globe (eyeball0 that are responsible for turning and rotating the eye.  Each eye has four rectus and two oblique muscles.

Eyelids – Moving folds of skin that cover the outer portion of the eyeball.  The eyelids protect the eve from injury and aid the lubrication of the eye’s surface. top

F

Farsightedness
Farsightedness or hyperopia, occurs when light entering the eye focuses behind the retina,
instead of directly on it.

Farsightedness – A refractive condition of the eye, resulting from the tendency of rays of light to focus behind the retina when accommodation is relaxed.  In mild amounts this can cause blurred vision at near point.  In higher amounts vision is blurred at all distances.

Field of Vision – The entire area, which can be seen without shifting the gaze.
Flashes & Floaters
As the vitreous pulls free from the retina, it is often accompanied by light flashes or floaters.

Floaters – Small particles consisting of cells or fibrin, which move in the vitreous.

Fluorescein angiography (FLOR-uh-seen an-jee-AHG-ruh-fee) – A test to examine blood vessels in the retina, choroid, and iris. A special dye is injected into a vein in the arm and pictures are taken as the dye passes through blood vessels in the eye.  A common study in the retina doctor's office.

Focal Length – The distance between a lens and the position where the lens brings parallel light rays to a focus.

Focal Point – The position on the optical axis of a lens where parallel light rays are brought to a focus.

Focus – The point to which rays are converged after passing through a lens.

Fogging – A technique in subjective refraction of moving the refractive lens in a plus direction to initially cause a blurred image.  The eye tries to compensate for the blur, and when the lens is changed to approach the correct refraction, the eye is more relaxed and the refraction can be better refined.

Foreign Body
Foreign bodies might be superficial, or in more serious injuries, they may penetrate the eye.
Fornix – The are where the palpebral and bulbar conjunctiva meet.

Fovea – A small depression in the central retina at the back of the eye.  The part of the macula adapted for most acute vision.

Fuchs' Dystrophy
Fuchs’ dystrophy is an inherited condition that affects the delicate inner layer (endothelium) of the cornea.

Fundus – The back of the eye, which can be seen with an ophthalmoscope.

Fusion – The power of coordinating the images received by the two eyes into single mental image. top

G

Gas Permeable Lenses – Contact lenses that allow oxygen and carbon dioxide to pass through them.  Usually refers to a type of hard lens (RGP), although soft lenses are also gas permeable.

Giant Cell Arteritis
Temporal arteritis, also known as giant cell arteritis, is an inflammatory condition affecting the medium-sized blood vessels that supply the head, eyes, and optic nerves.

Glaucoma
Glaucoma is a disease caused by increased intraocular pressure (IOP) resulting either from a malformation or malfunction of the eye’s drainage structures.

Glaucoma – A progressive disease of the eye, which is characterized by pressures inside the eye being too high and causing the nerve fibers running through the optic nerve to slowly deteriorate.  There is no cure for glaucoma.  It is managed with various treatments including drops, laser treatment and traditional surgery.  A patient with glaucoma is not a candidate for laser vision correction.

Globe – More commonly known as the “eyeball.” top

H

Halo – A hazy ring around bright light, seen by some patients with refractive error.

Haze – A clouding of vision sometimes reported following Laser-PRK.  The condition usually corrects itself, after a period ranging from weeks to months.

Headaches
Headaches may occur for any number of reasons including:  sinus conditions, hypertension, allergies, tumors, hormonal changes, and most frequently, stress.

Herpes Simplex
Herpes simplex is a very common virus affecting the skin, mucous membranes, nervous system, and the eye.

Herpes Zoster
Herpes zoster, commonly known as shingles, is caused by the same virus responsible for chicken pox.

High Pressure in the Eye
Glaucoma is a disease caused by increased intraocular pressure (IOP) resulting either from a malformation or malfunction of the eye’s drainage structures.

Histoplasmosis (Ocular)
Histoplasmosis is caused by a fungus commonly found in the dust and soil of the Mississippi-Ohio River Valley region.

Hypermetropia – See Farsightedness.

Hyperopia
Farsightedness or hyperopia, occurs when light entering the eye focuses behind the retina, instead of directly on it.

Hyperopia – Farsightedness.  The length of the eye is too short and the light rays are focusing too far behind the retina.  Farsighted patients have trouble with near tasks and close up vision can be non-existent or difficult.  Distance vision may also be affected but it is usually clearer than the near vision when comparing the two.

Hypertropia – A condition in which one eye deviates upward.

Hyphema
Hyphema is a term used to describe bleeding in the anterior chamber (the space between the cornea and the iris) of the eye.

Hypopyon
An accumulation of pus in the front of the eye. top

I

Implantable Contact Lens (ICL) –  The Implantable Contact Lens or the Implantable Collamer Lens is a small foldable lens that is implanted through an incision so tiny that it closes without stitches. Due to the small incision, the procedure is minimally invasive and no corneal tissue is removed.  This lens is best suited for individuals who have moderate to severe nearsightedness.

Inferior Oblique – One of the six muscles of the eye that moves the pupil up, away from the midline and the top of the pupil aware from the nose.

Inferior Rectus – One of the six muscles of the eye that allows rotation around all three axes and moves the pupil down and towards the midline and the top of the pupil away from the nose.

Injection – A term sometimes used to mean congestion of ciliary or conjunctival blood vessels; redness of the eye.

Instillation – The process of placing drops on the surface of the eye through retraction of the lower lid.

Intraocular Lens (IOL) – An artificial lens put in the eye to replace the natural crystalline lens.

Intraocular Pressure (IOP) – The pressure of the contents of the eyeball.  Increased IOP can be an indicator of the unwanted steroid response, which could lead to secondary glaucoma.

Inward Turned Eyelid
Entropion, an eyelid that turns inward, is a problem that typically affects the lower lid.

Iris – The ‘colored’ portion of the eye.  This muscle actually contains a contracting and an expanding muscle within it.  It regulates the amount of light that enters the eye and controls the size of the pupil with its movements.

Iris Neovascularization
Rubeosis is a term that describes abnormal blood vessel growth on the iris and the structures in
the front of the eye.

Iris Nevus
A nevus is typically a flat, benign, pigmented area that may appear inside the eye or on its surface.

Iritis
Iritis is an inflammatory problem of the iris, the colored part of the eye.

Iritis – Inflammation of the iris, a condition marked by pain, discomfort from light, contraction of pupil, and discoloration of iris. top

J

Jaeger Test – A test for near vision, lines of reading matter printed in a series of various sizes of type.
Keratitis – An inflammation of the cornea. top

K

Keratoconus
Keratoconus is a degenerative disease of the cornea that causes it to gradually thin and bulge into a cone-like shape.

Keratoconus – A deformity in which the corneal curvature gets progressively steeper, making the cornea somewhat cone-shaped.

Keratometer – An instrument used to measure the radius of the anterior surface of the cornea, and the power and axis of the corneal cylinder if present.  It utilizes the mirror effect of the front surface of the cornea.

Keratomety – The measurement of the anterior curvatures of the cornea with a keratometer.

Keratoplasty – The graft of a donor cornea to replace a damaged or diseased one. top

L

Lacrimal Apparatus – The orbital structures that produce tears and the ducts that drain the excess fluid from the front of the eyes into the nose.

Lacrimal Gland – Part of the lacrimal apparatus that produces tears.  It is located in the lateral part of the upper lid just under the orbital rim.

Lacrimal Sac – Collection chamber for tears after they have left the eye and traveled through the canaliculi.

Laser Thermal Keratotomy (LTK) – Applying focalized light energy to the peripheral cornea to correct hyperopia (farsightedness).

LASIK – LAKIK, OR Laser In Situ Keratomileusis, is a surgical procedure to reduce refractive errors that cause near-sightedness, far-sightedness, and astigmatism, conditions that are historically corrected by spectacles or contact lenses.  First, the inner layers of the cornea are gently separated from the outer layers with a micro-surgical instrument.  Next, a cool ultraviolet laser applies pulses of energy on those inner layers of the cornea to slightly reshape and thin it. Because the cornea accounts for approximately 70% of the eye’s total light bending ability, slight changes can dramatically reduce an individual’s continued dependence on corrective lenses.

Lateral Canthus – The outer (temporal) side of the palpebral fissure.

Lateral Rectus – One of six ocular muscles, which controls rotation around the vertical axis and moves the pupil away from the midline.

Lens – The Lens is the clear structure located behind the pupil.  Its primary function is to provide fine-tuning for focusing and reading. The lens performs this function by altering its shape.  At about the age of 40 to 50, the lens becomes less flexible and presbyopia begins.  At about the age of 60 to 70, the lens becomes cloudy and hard which prevents light from entering as well.  This condition is called a cataract.

Limbus – The junction between the cornea and sclera. top

M

Macula – The small area of the central retina that surrounds the fovea which contains yellow pigment.  This region provides the most distinct vision in the retina.

Macular Degeneration
Age-related macular degeneration (ARMD) is a degenerative condition of the macula (the central retina).

Macular Edema
Cystoid macular edema (CME), or swelling of the macula, typically occurs as a result of disease, injury or more rarely, eye surgery.

Macular Hole
Macular hole is a problem that affects the very central portion of the retina.

Macular Pucker
Epi-retinal membrane (ERM) or macular pucker is a cellophane-like membrane that forms over the macula.

Manifest Refraction – A subjective refraction without use of cycloplegic drops.

Manual Refraction -  A subjective refraction that measures each eye individually and together with patient interaction and response.

Medical Canthus – The inner (nasal) side of the palpebral fissure.

Medical Rectus – One of the six muscles of the eye that controls rotation around the vertical axis and moves the pupil towards the midline.

Microkeratome – An incision device that removes precise amounts of surface of the cornea used for LASIK surgery.

Miotic – A drug that causes the pupil to contract.

Monovision – A type of correction procedure in which one eye is corrected for distance vision and the other is corrected for near vision.

Mydriatic – A drug that dilates the pupil.

Myopia
Nearsightedness or myopia, occurs when light entering the eye focuses in front of the retina instead of directly on it.

Myopia – Nearsightedness.  The eye is too long and the light rays are focusing too far in front of the retina. Nearsighted patients have very little trouble seeing up close but distance vision is blurry. top

N

Nasolacrimal Duct – The duct connecting the lacrimal sac and the nasal cavity.  Tears pass through the nasolacrimal duct after the lacrimal sac.

Near Point of Accommodation – The nearest point at which the eye can perceive an object distinctly.  It varies according to the power of accommodation.

Near Vision – The ability to perceive objects distinctly at normal reading distance, or about 14 to 16 inches from the eyes.

Nearsightedness
Nearsightedness or myopia, occurs when light entering the eye focuses in front of the retina instead of directly on it.

Nearsightedness – A refractive error in which, because the eyeball is too long in relation to its focusing power, the point of focus for rays of light from distant object is in front of the retina.

Neovascularization of the Cornea
New (neo) blood vessel growth (vascularization) on the cornea is often caused by contact lens complications.

Nevus (Choroidal)
A nevus is typically a flat, benign, pigmented area that may appear inside the eye or on its surface.

Nevus (Iris)
A nevus is typically a flat, benign, pigmented area that may appear inside the eye or on its surface.

Non-Toric Lens – A lens, which refracts rays of light equally in all meridians.

Nystagmus – An involuntary rapid movement of the eyeball.  May be lateral, vertical or rotary. top

O

Objective Refraction – A refraction performed without patient interaction or response.  Each eye is measured individually.  Binocular visual acuity is not measured.

Ocular Histoplasmosis
Histoplasmosis is caused by a fungus commonly found in the dust and soil of the Mississippi-Ohio River Valley region.

Ocular Rosacea
Ocular rosacea is associated with a chronic skin condition known as acne rosacea.

Oculi Uniter (O.U.) – Both eyes.

Oculus Dexter (O.D.) – Right eye.

Oculus Sinister (O.S.) – Left eye.

Ophthalmologist – An M.D. who specializes in diagnosis and treatment of defects and diseases of the eye, performing surgery when necessary or prescribing other types of treatment.

Ophthalmoscope – An instrument used in examining the interior of the eye, especially the fundus.

Optic Atrophy – Degeneration of the nerve tissue, which carries messages from the retina to the brain.

Optic Disc – Head of the optic nerve in the eyeball.  There is a complete absence of rods and cones here, thus it is insensitive to light and referred to as the blind spot.

Optic Nerve – The optic nerve serves to carry the nerve fibers of the retina to the brain.  If the optic nerves are damaged from trauma or disease then permanent loss of vision can occur.

Optic Neuritis – Inflammation of the optic nerve.

Optician -  One who grinds lenses, fits them into frames, and adjusts the adjusts the frames to the wearer.

Optometrist – A specialist in diagnosing and treating visual and optical disorders of the eye and vision care practitioner.

Orbit – The bony cavity in the skull that houses the globe, the extracular muscles, the blood vessels, and the nerves.

Outward Turned Eyelid
Patients with ectropion have a sagging lower eyelid that leaves the eye exposed and dry. top

P

Pachymetry – Ultrasound measurement of the corneal thickness.

Palpebral Conjunctiva – The portion of the conjunctiva that covers the inner surface of the eyelids.

Palpebral Fissure – The opening between the upper and lower lids.

Pathologic – Resulting from diseases of the structure and function of the body.

Peripheral Vision – The ability to perceive the presence, motion or color of objects outside of the direct line of vision.

Phacoemulsification – Use of ultrasound or laser energy to break up a cataract for ease of removal.

Phakic Lens – The natural lens.

Phoria – A latent deviation in which an eye has tendency to turn from the normal position for binocular vision when covered.  See Hyperphoria, Esophoria, Exophoria.

Photophobia – Abnormal sensitivity to and discomfort from light.

Photorefractive Keratectomy (PRK) – A procedure to correct refractive error by ablating the surface of the central area of the cornea using an excimer laser.  The laser beam ablation pattern is shaped to create the necessary corrective refraction.  At Beacon Eye Institute, referred to as Laser-PRK (bmct bmps/trademark.bmp)

Phototherapeutic Keratectomy (PTK) – A procedure to treat pathologic conditions of the surface of the cornea using an excimer laser.  The laser beam ablation pattern is flat to create a smoothing of the corneal surface.

Pinguecula
A pinguecula is a benign, yellowish growth that forms on the conjunctiva.

Pink Eye
Conjunctivitis, commonly known as pink eye, is an infection of the conjunctiva (the outer-most layer of the eye that covers the sclera).

Posterior Capsular Opacification
PC haze can occur when the remaining portion of the capsule becomes clouded...about 25% of cataract surgery patients.

Posterior Chamber – The narrow space between the back of the iris and the front surface of the crystalline lens, bounded by the ciliary body.

Posterior Segment – All parts of the eye behind the crystalline lens; the vitreous and the retina.
Presbyopia
Presbyopia, also known as the “short arm syndrome,” is a term used to describe an eye in which the natural lens can no longer accommodate.

Presbyopia – The age-related inability of the crystalline lens to change or accommodate to focus on near objects (normally occurs in individuals over age 40).  Patients require a prescription to see tasks clearly up close.

Pseudophakic Lens – A surgically implanted lens.

Pterygium
Pterygium is a raised, wedge-shaped growth of the conjunctiva. Pterygium is a fleshy growth that invades the cornea. If the pterygium is large enough to threaten sight, is growing or is unsightly, it can be removed surgically.

Pterygium – A triangular fold of growing membrane, which may extent toward the cornea from the sclera. 

Ptosis
Ptosis (pronounced toe' sis), or drooping of the upper eyelid, may occur for several reasons such as: disease, injury, birth defect, previous eye surgery and age. Ptosis – A paralytic drooping of the upper eyelid.

Punctum (puncta) – Tiny openings on the nasal side of the upper and lower lids through which excess tears pass when leaving the eye.

Pupil – The pupil is the “black circle” that you see in the center of a person’s eye.  The primary function of the pupil is to control the amount of light entering the eye.  When you are in a bright environment, the pupil becomes smaller to allow less light through.  When it is dark, the pupil expands to allow more light to reach to back of the eye. top

R

Radial Keratotomy (RK) – A surgical procedure in which radial incisions are made in the peripheral cornea to flatten the central portion of the cornea and correct myopic refractive errors.

Recurrent Corneal Erosion
Recurrent corneal erosion is a condition affecting the outermost layer of corneal cells called the epithelium.

Refraction – In optics, the bending of light rays as they travel from one medium to another. Also a test to determine the refractive error of an eye and the best corrective lenses to be prescribed.

Refractive Error – A defect in the eye that prevents light rays from being brought to a single focus exactly on the retina.

Retina – Inner-back surface of the eye.  The retina contains light-sensitive cells that convert light to electric impulses that are carried to the brain.

Retinal Detachment
A retinal detachment occurs when the retina’s sensory and pigment layers separate.

Retinal Detachment – A separation of the retina from the choroid.

Retinal Pigment Epithelium (RPE) (ep-ih-THEE-lee-um) – The pigment cell layer that nourishes the retinal cells; located just outside the retina and attached to the choroid.

Retinal Tear
Retinal tears commonly occur when there is traction on the retina by the vitreous gel inside the eye.

Retinal Vein Occlusion occurs when the circulation of a retinal vein becomes obstructed by an adjacent blood vessel, causing hemorrhages in the retina.

Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a rare, hereditary disease that causes the rod photoreceptors in the retina to gradually degenerate.

Retinopathy of Prematurity
Retinopathy of Prematurity (ROP), also known as retrolental fibroplasia, is a potentially
blinding condition affecting the retina of newborns.

Retinoscope – A hand-held instrument for determining the refractive state of the eye.  It throws light from a moving mirror onto the retina, creating a movement of lights and shadows across the pupil.

Rod – One of the two types of light-sensitive cells in the eye.  Rod cells are responsible for vision in poor light and, apart from the central region and the blind spot, are found throughout the retina. top

S

Sclera – White tissue (the white part of the eye) that forms the main structural component of the globe (eyeball).  The scleral tissue is continuous from the cornea on the front of the eye to the optic nerve sheath in the back of the eye.

Scleritis
Scleritis is an inflammatory disease that affects the conjunctiva, sclera, and episclera (the
connective tissue between the conjunctiva and sclera).

Scleritis – Inflammation of the sclera.

Sebaceous Gland – A gland that provides fatty lubrication to surrounding areas.

Slit Lamp – A corneal microscope, which provides a narrow beam of strong light, for examination of the front portions of the eye.

Snellen Chart – Used for testing central visual acuity.  It consists of lines of letters, numbers or symbols in graded sizes drawn to Snellen measurements.  Each size is labeled with the distance at which it can be read by the normal eye.  Most often used for testing vision at 20 feet.

Soft Contact Lens – A contact lens made of soft plastic, which contains water and allows for oxygen transmission.  Soft lenses are characterized by comfort and ease of adaptation.  A soft contact lens is used to protect the cornea following Laser-PRK, aiding the healing process of the epithelium by reducing septic exposure.

Spherical Lens – See Non-toric lens.

Stereoscopic Vision – The ability to use both eyes together to perceive the solidity and depth of objects in space.

Strabismus
Strabismus is a problem caused by one or more improperly functioning eye muscles, resulting in a misalignment of the eyes.

Strabismus – Sometimes called squint, a failure of the two eyes simultaneously to direct their gaze at the same object because of muscle imbalance.  See Tropia, Esotropia, Exotropia.

Stye
A chalazion (stye) is a small lump in the eyelid caused by obstruction of an oil producing or meibomian gland.

Stye – Acute inflammation of a sebaceous gland in the margin of the eyelid, due to infection and usually resulting in the formation of pus.

Subconjunctival Hemorrhage
Subconjunctival hemorrhage occurs when a small blood vessel under the conjunctiva breaks and bleeds.

Subjective Refraction – A refraction where patient response to alternative correction is performed.  It includes measurement of each eye individually and both eyes together.

Superior Oblique – One of the six muscles of the eye that allows rotation around all three axes and moves the pupil down and away from the midline and the top of the pupil towards the nose.

Superior Rectus – One of the six muscles of the eye that allows rotation around all three axes and moves the pupil up and towards the midline and the top of the pupil towards the nose. top

T

Temporal Arteritis
Temporal arteritis, also known as giant cell arteritis, is an inflammatory condition affecting the medium-sized blood vessels that supply the head, eyes, and optic nerves.

Tonometer – An instrument for measuring pressure inside the eye

Toric Lens – A lens, which has differing radii of curvature in different meridians, which causes the refractive  power to vary in the different meridians.  Used in the correction of astigmatism.

Trabecular Meshwork – Spongy structure that filters the aqueous and controls its rate of flow out of the eye.

Tropia – A deviation of the eyes from their normal straight alignment. top

U

Uncorrected Visual Acuity (UCVA) – The vision the patient has when they are not using any prescription to help them out.  Also known as “naked vision.”

Unilateral – Relating to or affecting only one eye or one eye at a time.

Uveal Tract (Uvea) – Collective name for the iris, ciliary body, and choroid.

Uveitis
Uveitis is a general term that refers to inflammation or swelling of the eye's structures
responsible for its blood supply. top

V

Vein Occlusion
Retinal vein occlusion occurs when the circulation of a retinal vein becomes obstructed by an adjacent blood vessel, causing hemorrhages in the retina.
Vision – Sight, the faculty of seeing.

Visual Acuity – Ability of the eye to perceive the shape of objects in the direct line of  vision, usually measured in terms of a Snellen fraction, such as 20/20.

Visual Cortex – The area of the brain that receives visual information.
Vitreous – The gelatinous, transparent, colorless substance filling the space in the eyeball between the crystalline lens and the retina.

Vitreous Detachment
The vitreous space is located posteriorly between the lens of the eye and the retina. top

Y

Yag Peripheral Irodotomy – Use of a laser to put holds in the iris to help relieve pressure by allowing aqueous outflow.
Yag Posterior Capsulotomy – Use of a laser to put holes in the posterior chamber that has become opaque. top

Z

Zonules -  Transparent fibers that radiate from the crystalline lens and attach to the ciliary body.