Certified Ophthalmic Assistant (COA) Study Guide - JCAHPO

When reading add power on the lensometer take the difference between the triple line target distance reading and the _____.

A. Single line distance reading

B. Triple line bifocal reading

C. Single line bifocal reading

D. Zero point

B. Triple line bifocal reading

What is a yellow top on eye drops for?

A. Carbonic anhydrase inhibitors

B. Prostaglandin analogues

C. Beta-blockers

D. Cycloplegics

C. Beta-blockers

* Can also be light blue!

* Used to treat glaucoma; it helps to decrease the production of aqueous humor and reduce IOP

* Examples:

- Timolol

- Levobunolol

- Betaxolol (light blue top)

The purpose of keratometry is to measure:

The curvature of the anterior corneal surface

An eye alignment deviation that is not present unless fusion is disrupted is called a:

A. Phoria

B. Tropia

C. Hyper deviation

D. Eso deviation

A. Phoria

* Tropia and Phorias are terms to describe when the eyes are not in alignment with each other

* A tropia is always present, while phorias are there "some of the time," such as when the patient is tired or when fusion is broken (you cover an eye and it starts to drift).

The endpoint of the Maddox Rod test occurs when:

A. The red dot is superimposed on the light

B. The red line goes through the light

C. The red line disappears

D. The red line is above the light

B. The red line goes through the light

A condition in which blood has settled in the bottom half of the anterior chamber of the eye is called a:

A. Subconjunctival hemorrhage

B. Pink eye

C. Hyphema

D. Glaucoma

C. Hyphema

* A subconjunctival hemorrhage will only involve the white of the eye, not the center, and will typically have no pain associated with it

* A hyphema will only affect the center of the eye, behind the cornea, and will usually have pain and additional symptoms associated with it

An outward deviation of the eye(s) is a(n) ____ and an inward deviation of the eye(s) is called a(n) ______.

A. Esodeviation / Exodeviation

B. Esophoria / Exophoria

C. Exodeviation / Esodeviation

D. Exophoria / Esophoria

C. Exodeviation / Esodeviation

* Esotropia means that one eye is deviated inward and is often called crossed eyes

* Exotropia is when one or both eyes look outward, often called wall-eyed

* A tropia is always present, while phorias are there "some of the time".

Kinetic perimetry means that the light stimulus is:

A. Moving from an area of non-seeing to an area of presumed seeing

B. A stimulus that is presented to the patient but not moved

C. A situation in which visual fields are performed without either eye being occluded

D. The stimulus is jiggled slightly so the patient can see it

A. Moving from an area of non-seeing to an area of presumed seeing

* The two most commonly used types of perimetry are Goldmann kinetic perimetry and threshold static automated perimetry

What is the name of the condition where a fibrovascular growth forms on the conjunctiva to a portion of the cornea?

A. Pterygium

B. Pinguecula

C. Exteration

D. Entropion

A. Pterygium

* A pinguecula is characterized by a yellowish raised growth on the conjunctiva typically at the nasal or temporal conjunctiva near the edge of cornea

* Pterygium is the triangular shape of vascularized conjunctival tissue on the cornea and it invades the cornea (known as fibrovascular invasion of the cornea)

Forward displacement of the eye in it's bony socket causing the eye to bulge forward is termed:

A. Exophthalmos

B. Neoplasia

C. Buphthalmos

D. Exophasia

A. Exophthalmos

* Exophthalmos is a normal-sized globe that is being pushed forward by a space-occupying lesion in the orbit.

* Buphthalmos is a normally-positioned globe that is enlarged due to elevated intraocular pressure, i.e., glaucoma

_____ is the distance from the front surface of the cornea to the back side of a lens that is mounted in a frame and being worn by the patient.

A. Back vertex

B. Lens vertex

C. Vertex distance

D. Front vertex

C. Vertex distance

A non-contact lens to examine the macula is:

A. Goniolens

B. Hruby lens

C. Koeppe lens

D. Maddox lens

B. Hruby lens

* It is held immediately in front of the cornea and forms a virtual, erect, and minified image of the retina

* A Koeppe lens allows examination of both the angle and the posterior pole

Which blood vessels have valves?

A. Veins

B. Arteries

C. Capillaries

D. Arterioles

A. Veins

What major microbial categories may be associated with eye infections?

A. Bacteria and viruses

B. Fungus

C. Parasites

D. All of the above

D. All of the above

- Bacteria

- Viruses

- Fungus

- Parasites

A condition in which the steepest corneal meridian is in the vertical plane, an example of keratometer reading for a patient exhibiting this condition would be:

K's: 42.00 @ 180/45.00 @ 90

With the Rule Astigmatism

The angle of an eyeglass lens in relation to the vertical plane

Pantoscopic tilt

Inflammation of the tear sac associated with faulty tear drainage is:

A. Trichiasis

B. Blepharitis

C. Conjunctivitis

D. Dacryocystitis

D. Dacryocystitis

The swelling of the optic disc with engorged blood vessels is known as:

A. Papilledema

B. Endophthalmitis

C. Optic nerve compression

D. Anterior ischemic optic neuropathy

A . Papilledema

* Endophthalmitis is a purulent inflammation of the intraocular fluids (vitreous and aqueous) usually due to infection

* Optic nerve compression occurs when a formation around the brain — such as a tumor or bony structure — presses on the optic nerve and affects its performance

* Anterior ischemic optic neuropathy (AION) is a sudden loss of vision due to an interruption of blood flow to the front (anterior) of the optic nerve

The measurement of the refractive error of an eye

Refractometry

_____ is a major contributing factor in contracting the parasitic organism Acanthamoeba.

A. Cataract surgery

B. Contact lens wear

C. Eye surgery

D. LASIK surgery

B. Contact lens wear

* Acanthamoeba Keratitis is a rare but serious infection of the eye that can result in permanent visual impairment or blindness

Which of the following is an example of static visual field testing?

A. Zeiss Visual Field

B. Confrontational fields

C. Goldmann

D. Tangent Screen

A. Zeiss Visual Field

* A static field of vision test involves illuminating an object that doesn't move in the patient's field of vision in order to test the vision in this manner

* A kinetic visual field test involves moving an object in and out of a patient's peripheral vision in order to find the edge of the patient's field of vision

Which of the following is NOT accurate regarding the use of medications to dilate the pupil?

A. Tropicamide paralyzes the sphincter muscle

B. Atropine has a short duration of action

C. Phenylephrine stimulates the dilator muscle

D. Tropicamide and other cycloplegic agents can be used for pain relief in eyes with iritis

B. Atropine has a short duration of action

* Atropine will cause blurred vision which may last up to seven days or more after using it

* The pupil may also remain dilated for up to 14 days

What symptoms are associated with acute conjunctivitis? (select multiple)

A. Discharge/tearing

B. Pain

C. Sneezing/coughing

D. Blurred vision

A, B, and D

Discharge/tearing, pain, and blurred vision

* Also called pink eye

* Patient may experience:

- Pain in the eyes

- Red, irritated eyes

- Sensitivity to light

- Itchiness

- Discharge/crust

Explain transposition

Transposition is the conversion of an eyeglass prescription from plus cylinder form to minus cylinder form or vice versa.

- First, add the sphere and cylinder powers

Example: +2.00 -2.50 x 90 = -0.50 -2.50 x 90

- Retain the cylinder power but flip the sign

Example: -0.50 -2.50 x 90 = -0.50 +2.50 x 90

- Change axis by 90 degrees

Example: -0.50 +2.50 x 90 = -0.50 +2.50 x 180

_____ are eye drops that cause the pupil to constrict, allowing the blocked drainage angle to open.

A. Cycloplegic

B. Mydriatic

C. Miotics

D. Beta-blockers

C. Miotics

* Miotics = drugs that cause the pupil to contract

* They improve the outflow of aqueous as part of the treatment of glaucoma and reduce the risk of a posteriorly luxated lens entering the anterior chamber

All injuries to the globe should be treated as though it may be a(n) __________ until a diagnosis is made by the physician.

A. Corneal foreign body

B. Corneal abrasion

C. Ruptured globe

D. Infection

C. Ruptured globe

* Globe rupture is an ophthalmologic emergency and requires definitive management by an ophthalmologist. Although the globe's position within the orbit protects it from injury in many situations, damage to the posterior segment of the eye is associated with a very high frequency of permanent visual loss.

What is the difference between ptosis and dermatochalasis?

* Ptosis is caused by a weakening of muscle that results in the upper eyelid drooping over the eye.

* Dermatochalasis is caused by excess skin, fat, or muscle in the eyelid area.

What type of astigmatism means that the eye is steeper in the vertical meridian?

A. oblique astigmatism

B. with the rule astigmatism

C. irregular astigmatism

D. against the rule astigmatism

B. With the rule astigmatism

* more plus

* steeper axis at 90 degrees

* more common in younger patients and myopic eyes

What is a dark green top on eye drops for?

A. Miotics

B. Beta-blockers

C. Mydriatics

D. NSAIDS

A. Miotics

* Constricts the pupil

* Used for decreasing IOP in angle closure glaucoma by increasing aqueous humor outflow via the trabecular meshwork pulling the peripheral iris which blocks the trabeculum.

Name three types of ophthalmic preparations placed directly in the eye.

- Solutions

- Suspensions

- Ointments

An A-scan measurement with the echo perpendicular to the retina will produce a retina spike that will:

A. Be a sharply rising spike

B. Be a tall spike

C. Have no smaller spikes preceding it

D. Have a 90 degree angle to the baseline

E. All of the above

E. All of the above

Name the condition in which there is a defect in the superior or inferior portion of the visual field that respects the horizontal midline.

A. Bitemporal hemianopia

B. Homonymous hemianopia

C. Altitudinal Visual Field Defects

D. Bitemporal hemianopsia

C. Altitudinal Visual Field Defects

* Altitudinal defects occur in retinal vascular disease, glaucoma, and other disorders that affect the eye itself.

Amsler grid testing plots visual field loss within the central _____ degrees of the visual field.

A. 20

B. 10

C. 20

D. 15

C. 20

Without rods, which condition will occur?

Night-blindness

* Rods are a type of photoreceptor cell present in the retina that transmits low-light vision and is most responsible for the neural transmission of nighttime sight.

Which of the following is associated with pupil constriction?

A. Light

B. Accommodation

C. Convergence

D. All of the above

D. All of the above

True or false?

The right Medial Rectus is the antagonist of the right lateral rectus.

True

* An antagonist is a muscle in the same eye that moves it in the opposite direction.

* Three antagonistic pairs of muscles control eye movements:

- The lateral and medial rectus muscles

- The superior and inferior rectus muscles

- The superior and inferior oblique muscles

The Medial Rectus muscle rotates the eye:

A. Inward towards the nose

B. Outward towards the temple

C. Downward and inward towards the nose

D. Downward and outward towards the temple

A. Inward towards the nose

Version and ductions are tested by using ______ to test the six pairs of ______ muscles.

The six cardinal positions

yoke

* Yoke muscles are pairs of muscles, one in each eye, that produce conjugate eye movements. Example- right superior rectus and left inferior oblique.

* Versions are a tropia or phoria of both eyes in the same direction

* Ductions are a tropia or phoria of one eye alone

Nystagmus indicates a problem with the _____ not the _____.

A. Brain / retina

B. Extraocular muscles / brain

C. Retina / brain

D. Brain / extraocular muscles

D. Brain / extraocular muscles

* Nystagmus is an involuntary eye movement that may cause the eye to rapidly move from side to side, up and down, or in a circle, and may slightly blur vision.

The suffix "-algia" refers to:

A. Pain

B. Hearing

C. Fungi

D. Rashes

A. Pain

What is axial length?

A. The measure of length between the crystalline lens to the macula

B. The measure of length from the cornea to the crystalline lens

C. The measure of length from the anterior cornea to the anterior retina

D. The measure of length from the anterior cornea to the posterior retina

D. The measure of length from the anterior cornea to the posterior retina

Which of the conditions listed below may be characterized by a white pupillary reflex in a pediatric patient?

A. Choroidal nevus

B. Congenital glaucoma

C. Iris coloboma

D. Retinoblastoma

D. Retinoblastoma

* Retinoblastoma is a disease in which malignant (cancer) cells form in the tissues of the retina.

Explain Spherical Equivalent

* Take half the cylinder and add to the sphere

* Drop the cylinder and axis and write sphere only

Example:

-2.00 -0.50 145

(half the cylinder) -0.25

(add to sphere) 0.25 + 2.00

Answer: -2.25 sphere

______ are deposits of lipids, proteins, and cellular debris which are found within the layers of the retina.

A. Macular stones

B. Cholesterol stones

C. Drusen

D. Congestive papillae

C. Drusen

* Drusen are yellow deposits under the retina that are made up of lipids and proteins.

* Drusen can be different sizes—small, medium, and large. Small drusen are common in those 50 and older without age-related macular degeneration (AMD). But having many small drusen and larger drusen are often signs of AMD.

Which one of the following stains is useful for determining the inflammatory cellular response to a particular agent?

A. Giemsa's

B. Gram's

C. Sabouraud's

D. Safranin

A. Giemsa's

Name the organism that is most destructive to the eye.

Pseudomonas Aeruginosa

*In the eye, P. aeruginosa is a common cause of bacterial keratitis, particularly in contact lens wearers. It is known to be particularly virulent, with pseudomonas keratitis being more difficult to treat and have worse prognosis than other forms of bacterial keratitis.

* P. aeruginosa secretes proteases that can cause liquefactive necrosis of the cornea, leading to rapid corneal weakening and perforation.

Solutions with a pH less than 7 are said to be:

Acidic

What is an orange top on eye drops for?

A. Carbonic anhydrase inhibitors

B. Alpha adrenergic agonists

C. Prostaglandin analogues

D. Beta blockers

A. Carbonic anhydrase inhibitors

* Mainly used to treat glaucoma or other high IOP related conditions

* Helps to decrease IOP

* Examples:

- Dorzolamide

- Brinzolamide

The concentration of the chemical in that solution

Tonicity

ung (unguentum)

ointment

The oil-secreting glands found in the posterior margin of the eyelid

Meibomian glands

* Meibomian glands are oil glands along the edge of the eyelids where the eyelashes are found.

* These glands make oil that is an important part of the eye's tears. The oily layer is the outside of the tear film that keeps tears from drying up too quickly.

Name the 5 layers of the cornea

Epithelium

Bowman's membrane

Stroma

Descemet's membrane

Endothelium

Amaurosis fugax is:

A. A bacterial infection

B. A viral infection

C. The symptom of temporary vision loss

D. A retinal disease

C. The symptom of temporary vision loss

* Refers to a transient monocular visual loss, and is usually caused by atherosclerotic emboli that leads to retinal artery occlusion, or other conditions, such as inflammation of the associated nerves and/or arteries

A relative scotoma is:

A. An area the patient cannot see at all

B. An area of fluctuating vision

C. The physiologic blind spot

D. An area requiring a brighter or bigger stimulus to see

D. An area requiring a brighter or bigger stimulus to see

What is an important factor in the delivery of eye medications?

Prolonging medication contact time with the eye

What structure secretes aqueous fluid and serves as an attachment site for zonules?

Ciliary processes

Lateral and medial rectus muscles move the eye _____.

A. Left

B. Down

C. Vertically

D. Horizontally

D. Horizontally

* The medial rectus is an adductor (pulls the eye towards the nose)

* The lateral rectus is an abductor (pulls the eye away from the nose)

A different A-scan instrument setting must be used for a phakic scan vs. an aphakic scan because of a different:

A. Gain setting

B. Reflectivity

C. Spike height

D. Velocity of sound

D. Velocity of sound

All extraocular muscles are associated with the 3rd cranial nerve EXCEPT:

A. Lateral Rectus and Superior Oblique

B. Medial Rectus and Inferior Oblique

C. Superior Oblique and Inferior Oblique

D. Lateral Rectus and Medial Rectus

A. Lateral Rectus and Superior Oblique

* LR = 6th cranial nerve

* SO = 4th cranial nerve

* All others = 3rd cranial nerve

Define palsy

Decreased strength of a muscle, which produces a reduced rotational movement of the eyeball in the direction corresponding to the paralyzed muscle

Which of the following echoes will always be absent in the axial length scan of an aphakic patient?

A. Cornea spike

B. Posterior lens capsule spike

C. Anterior lens capsule spike

D. Retina spike

C. Anterior lens capsule spike

_____ is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus.

A. Epicanthus

B. Blepharophimosis

C. Dermatochalasis

D. Ptosis

A. Epicanthus

* Epicanthus = upper eyelid

* Covers the corner of the eye

Which term means "on the same side of each eye"?

A. Homonymous

B. Hemianopsia

C. Incongruous

D. Congruous

a. Homonymous

Match the cranial nerve and extraocular muscle.

EOMs:

Superior Oblique

Inferior Oblique

Lateral Rectus

Medial Rectus

Superior Rectus

Inferior Rectus

Cranial Nerves:

3

4

6

Superior Oblique - 4

Inferior Oblique - 3

Lateral Rectus - 6

Medial Rectus - 3

Superior Rectus - 3

Inferior Rectus - 3

What type of corneal astigmatism does a keratometry reading of 42.25/44.75 x 90 indicate?

A. With-the-rule

B. Against-the-rule

C. Abnormal

D. No astigmatism

A. With-the-rule

* With-the-rule astigmatism means that the strongest axis is the vertical axis (90 degrees) in plus cylinder which is the same as 180 degrees minus cylinder

Which of the following describes a prodrug?

A. Activation usually occurs in the tear film

B. It requires modification to be an active drug

C. Prodrugs typically have poor ocular penetration

D. It must be fully dissolved in a liquid vehicle

B. It requires modification to be an active drug

What is a light green top on eye drops for?

A. Adrenergic agonist combinations

B. Miotics

C. Alpha adrenergic agonists

D. Antibiotics

A. Adrenergic agonist combinations

* Used in the treatment of glaucoma

* Brinzolamide-Brimonidine (Simbrinza)

Lipid exudates usually present with which of the following pathologies?

A. Diabetic macular edema

B. Cystoid macular edema

C. Retinoschisis

D. Hemorrhage

A. Diabetic macular edema

* Diabetic macular edema (DME) is manifested as retinal thickening caused by the accumulation of intraretinal fluid, primarily in the inner and outer plexiform layers.

* DME can be present with any level of diabetic retinopathy.

Aberration

Distortions, related to astigmatism, that cause the inability of light rays entering the eye to converge to a single focus point on the retina. Aberration are divided into two main categories, higher-order and lower-order

The nasolacrimal duct drains directly into the:

A. Frontal sinus

B. Nose

C. Esophagus

D. Larynx

B. Nose

Which of the following is not likely to cause a miotic pupil?

A. Pilocarpine

B. Iris inflammation

C. Old age

D. Phenylephrine

D. Phenylephrine

* Phenylephrine is used to dilate (enlarge) the pupil

* Miotic = a drug that causes the pupil of the eye to contract by constricting the ciliary muscle

A decrease in visual acuity and/or visual field that is not caused by an organic brain lesion or stroke would be called a/an:

A. Constricted field defect

B. Hemianopic field defect

C. Incongruous field defect

D. Functional field defect

D. Functional field defect

You want to check the action of the Left Inferior Oblique muscle. Where do you direct the patient to look?

A. To the left

B. Down and right

C. Up and left

D. Up and right

D. Up and right

What cranial nerves are associated with the Superior Oblique and Inferior Oblique?

A. 3rd and 4th

B. 6th and 5th

C. 4th and 3rd

D. 4th and 6th

C. 4th and 3rd

Which muscles are elevators?

A. Superior Rectus and Inferior Rectus

B. Superior Rectus and Superior Oblique

C. Inferior Oblique and Superior Rectus

D. Inferior Oblique and Superior Oblique

C. Inferior Oblique and Superior Rectus

Cover testing can be useful in all of the following patients except:

A. Bilateral aphakic

B. Bilateral pseudophakic

C. The patient with suppression

D. The monocular patient

D. The monocular patient

What type of drops are used to dilate the eyes?

Mydriatic drops

What is a purple top on eye drops for?

A. NSAIDS

B. Alpha adrenergic agonists

C. Beta blocker combinations

D. Adrenergic agonist combinations

B. Alpha adrenergic agonists

* Used in the treatment of glaucoma

* Reduces IOP by decreasing the production of aqueous humor and increases the outflow of aqueous drainage via uveoscleral outflow.

* Example:

- Brimonidine (Alphagan)

An axial scan is performed to show the position of pathology in relation to:

A. The cornea and the ciliary body

B. The back of the iris

C. The eyelids

D. The anatomy of the posterior lens surface and optic nerve

D. The anatomy of the posterior lens surface and optic nerve

When changing the bulb in an instrument such as a projector, what should be done first?

A. Remove the housing

B. Turn the instrument switch off

C. Unplug the instrument

D. Call the maintenance department

C. Unplug the instrument

What is the vertical limit (measured from the horizontal line of sight) of the normal visual field?

A. 110 degrees

B. 90 degrees

C. 30 degrees

D. 60 degrees

D. 60 degrees

In what type of glaucoma does the anterior chamber angle become blocked by the iris, resulting in pain, redness, and blurred vision?

A. Pigmentary glaucoma

B. Angle-closure glaucoma

C. Neovascular glaucoma

D. Low tension glaucoma

B. Angle-closure glaucoma

What drug classification is contraindicated in patients with obstructive pulmonary disease or cardiovascular disease?

Beta Blockers

What is the condition in which the eyes shift involuntarily in a rhythmic beating motion?

Nystagmus

* Nystagmus is a vision condition in which the eyes make repetitive, uncontrolled movements.

* These movements often result in reduced vision and depth perception and can affect balance and coordination.

* These involuntary eye movements can occur from side to side, up and down, or in a circular pattern.

Name the 5 basic requirements for ophthalmic preparations.

- Tolerance

- Tonicity

- Sterility

- Stability

- Penetration

What is the name of the clear gel that fills the space between the lens and the retina?

A. Aqueous humor

B. Vitreous humor

C. Tears

D. Mucus

B. Vitreous humor

* The vitreous humor's main role is to maintain the round shape of the eye

* The other functions include vision clarity and to absorb shock to the head or the eye

Most ophthalmic solutions have a pH that varies from ___ to ___.

3.5 to 10.5

Near vision charts are designed to be read at:

14-16 inches

It takes the rods about ____ minutes to dark adapt.

A. 5

B. 10

C. 15

D. 30

D. 30

For which disease is a family history least important?

A. Glaucoma

B. Macular degeneration

C. Retinal detachment

D. Cataract

D. Cataract

- Cataracts typically occur for every individual over the course of aging.

A grey top on eye drops is for?

NSAIDS

Intorsion refers to:

A. Rotation of the eye around the vertical axis

B. A temporal rotation of the eye from the 12 o'clock position

C. A nasal rotation of the eye from the 12 o'clock position

D. Rotation of the eye around the horizontal axis

C. A nasal rotation of the eye from the 12 o'clock position

The "insulation" around nerve fibers are called:

A. Myelin

B. White matter

C. Ganglia

D. Plexus

A. Myelin

Which iris muscle contracts to decrease the amount of light entering the eye?

A. Dilator

B. Constrictor

C. Sphincter

D. Rectus

C. Sphincter

The Maddox Rod test can be done:

A. Only with the eyes in primary gaze

B. In all fields of gaze

C. As an objective measurement

D. Only at a distance, to avoid accommodation

B. In all fields of gaze

What is the condition where parallel rays of light come to focus at a point just in front of the retina with respect to the unaccommodated eye?

A. Myopia

B. Cycloplegia

C. Hyperopia

D. Emmetropia

A. Myopia

Patients most commonly cite which systemic drug as producing an allergic or bad reaction?

A. Acetaminophen

B. Ampicillin

C. Tetracycline

D. Tobramycin

B. Ampicillin

Phenylephrine 10% should be used cautiously with patients who:

A. Have a heart disease

B. Have hypertension

C. Are infants

D. All of the above

D. All of the above

* There have been reports of serious cardiovascular reactions, including ventricular arrhythmias and myocardial infarctions, in patients using phenylephrine 10%. These episodes, some fatal, have usually occurred in patients with pre-existing cardiovascular diseases.

(Source: https://www.drugs.com/pro/phenylephrine-ophthalmic-solution.html#:~:text=Contraindications,-4.1%20Cardiac%20and&text=and%20Endocrine%20Disease-,Phenylephrine%20Hydrochloride%20Ophthalmic%20Solution%2C%20USP%2010%25%20is%20contraindicated%20in%20patients,be%20used%20in%20these%20patients.)

Which eye drop inactivates the sphincter muscle of the iris?

A. Cycloplegic

B. Anesthetic

C. Miotic

D. Mydriatic

A. Cycloplegic

What are the 3 layers of tears, in order?

A. Oily, mucin, aqueous

B. Mucin, oily, aqueous

C. Aqueous. mucin, oily

D. Oily, aqueous, mucin

D. Oily (outer), Aqueous (middle), and Mucin (inner).

* The 3 layers work together to help maintain the health of our eyes and ward off infection