Free COA® Practice Test: Sample Questions with Answers
An independent study tool for the IJCAHPO (JCAHPO) Certified Ophthalmic Assistant exam. Not affiliated with or endorsed by IJCAHPO.
The Certified Ophthalmic Assistant (COA) exam has 200 multiple-choice questions in 3 hours, drawn from 22 content areas. Below are 32 practice questions from EyeTech Prep's COA question bank, one or two from each content area, with the answer and an explanation under each one. They are practice questions written for this site, not questions from the exam itself.
Choose your answer before you open “Show answer”. Each content area ends with a link to its free study guide. For who can take the exam and how to apply, see how to get COA certification.
32 Free COA Practice Questions by Content Area
History and Documentation
9% of the examQuestion 1
Which item does NOT belong in the history of present illness?
- A. What makes the symptom better or worse
- B. Whether one eye or both are affected
- C. Symptoms that accompany the main complaint
- D. The patient's insurance plan and copay
Show answer to question 1
Answer: D. The patient's insurance plan and copay
The HPI holds only clinical characterization of the complaint — modifying factors, laterality, timing, and associated symptoms. Billing details live in the administrative record, not the medical history.
Question 2
In chart notation, 'OS' refers to:
- A. Both eyes
- B. The right eye
- C. The left eye
- D. Without correction
Show answer to question 2
Answer: C. The left eye
OS (oculus sinister) is the left eye, OD (oculus dexter) the right, OU (oculus uterque) both. Because OD also means 'once daily' in pharmacy notation, many clinics prefer writing 'right eye'/'left eye' in full.
General Medical Knowledge
8% of the examQuestion 3
Which structure of the eye provides approximately two-thirds of its total refractive power?
- A. Cornea
- B. Crystalline lens
- C. Aqueous humor
- D. Vitreous humor
Show answer to question 3
Answer: A. Cornea
The cornea provides approximately 43 diopters, which is about two-thirds of the eye's total refractive power.
Question 4
The fovea centralis contains the highest concentration of which type of photoreceptor?
- A. Rods
- B. Cones
- C. Bipolar cells
- D. Ganglion cells
Show answer to question 4
Answer: B. Cones
The fovea centralis has the highest concentration of cones, providing the sharpest visual acuity and color perception.
Ophthalmic Patient Services and Education
8% of the examQuestion 5
A patient uses both a drop and an ointment in the same eye. Correct teaching is:
- A. Apply the ointment first so the drop can penetrate it
- B. Instill the drop first and apply the ointment last
- C. Space them five minutes apart, in either order
- D. Use the drop one day and the ointment the next
Show answer to question 5
Answer: B. Instill the drop first and apply the ointment last
Ointment forms a barrier film — a drop placed on top of it cannot reach the eye. Drops go first; ointment seals the treatment. With multiple drops, wait about five minutes between them; the ointment still goes last.
Question 6
Patient education materials and verbal instructions work best when they:
- A. Cover several topics at once, in full detail
- B. Use full medical terminology to be precise
- C. Are given once, quickly, at checkout
- D. Use plain language and avoid medical jargon
Show answer to question 6
Answer: D. Use plain language and avoid medical jargon
Health-literacy research is clear: plain language, short sentences, and the teach-back check reach the most patients. "The pressure in your eye" lands; "your IOP is elevated secondary to…" does not.
Free Ophthalmic Patient Services and Education study guide →
Visual Assessment
7% of the examQuestion 7
A patient reads the 20/40 line. This means:
- A. They have 40% of normal vision
- B. Their acuity cannot be corrected
- C. They see at 40 feet what a normal eye sees at 20 feet
- D. They see at 20 feet what a normal eye sees at 40 feet
Show answer to question 7
Answer: D. They see at 20 feet what a normal eye sees at 40 feet
Snellen notation: test distance over the distance at which a normal eye reads that line. 20/40 = at 20 feet, the patient reads what a standard eye reads at 40.
Question 8
Standard testing distance for a near vision card is approximately:
- A. 36 inches / 90 cm
- B. 10 inches / 25 cm
- C. 24 inches / 60 cm
- D. 16 inches / 40 cm
Show answer to question 8
Answer: D. 16 inches / 40 cm
Near acuity is conventionally tested at 40 cm (16 in) with the patient's near correction in place.
Pupil Assessment
7% of the examQuestion 9
A relative afferent pupillary defect (Marcus Gunn pupil) is detected with:
- A. The swinging-flashlight test
- B. The near-reflex test
- C. The red-reflex test
- D. Corneal light reflex testing
Show answer to question 9
Answer: A. The swinging-flashlight test
Alternating the light between eyes reveals an RAPD: when the light swings to the affected eye, both pupils dilate instead of constricting because that eye's afferent (optic nerve/retina) signal is weaker.
Question 10
Light directed into the right eye causes the left pupil to constrict. The left eye's response is called the:
- A. Accommodative response
- B. Direct response
- C. Consensual response
- D. Afferent response
Show answer to question 10
Answer: C. Consensual response
The illuminated eye's constriction is the direct response; the fellow eye's simultaneous constriction is the consensual response, carried by the crossed fibers of the pupillary light pathway.
Tonometry
7% of the examQuestion 11
The generally accepted range of normal intraocular pressure is:
- A. 5–10 mmHg
- B. 10–21 mmHg
- C. 22–30 mmHg
- D. 30–40 mmHg
Show answer to question 11
Answer: B. 10–21 mmHg
Population studies place normal IOP at roughly 10–21 mmHg, though 'normal' varies by individual — some develop glaucoma within this range.
Question 12
The Goldmann drum reads 1.6 at the endpoint. The IOP is:
- A. 1.6 mmHg
- B. 160 mmHg
- C. 16 mmHg
- D. 8 mmHg
Show answer to question 12
Answer: C. 16 mmHg
The drum is calibrated in grams of force; multiplying by 10 converts to mmHg. 1.6 on the dial = 16 mmHg.
Pharmacology
6% of the examQuestion 13
By the standard cap-color convention, dilating drops (mydriatics/cycloplegics) have caps that are:
- A. Purple
- B. Yellow or blue
- C. Teal
- D. Red
Show answer to question 13
Answer: D. Red
Red caps mark mydriatics and cycloplegics; other classes have their own colors (e.g., yellow/blue beta blockers, teal prostaglandins). Color is a cross-check — the label is always read anyway.
Question 14
Recognizing drug classes by generic name endings: a medication ending in '-olol' is most likely a:
- A. Antibiotic
- B. Prostaglandin analog
- C. Beta blocker
- D. Anesthetic
Show answer to question 14
Answer: C. Beta blocker
Name stems are fast class clues: -olol beta blockers (timolol), -prost prostaglandins (latanoprost, travoprost), -caine anesthetics (proparacaine), -floxacin fluoroquinolones.
Visual Field Testing
6% of the examQuestion 15
The physiologic blind spot corresponds to:
- A. The fovea
- B. The optic disc
- C. The ora serrata
- D. The ciliary body
Show answer to question 15
Answer: B. The optic disc
The optic disc has no photoreceptors, producing a blind spot roughly 15° temporal to fixation in each eye's field.
Question 16
In the visit sequence, perimetry is performed:
- A. After the cycloplegic refraction
- B. Before dilating drops are instilled
- C. At the end of the visit, after the dilated exam
- D. During the dilation wait, whichever eye is ready
Show answer to question 16
Answer: B. Before dilating drops are instilled
Dilation changes pupil optics and adds glare and cycloplegic blur — all field-depressing artifacts. Fields (like acuity and pupils) belong on the pre-drop side of the visit.
Refractometry
5% of the examQuestion 17
During retinoscopy, "with" motion of the reflex is neutralized by:
- A. Adding minus power
- B. Adding plus power
- C. Rotating the axis 90°
- D. Increasing the working distance
Show answer to question 17
Answer: B. Adding plus power
"With" motion means the eye's far point lies beyond the examiner — add plus sphere until the reflex fills the pupil and no longer moves (neutrality). "Against" motion is neutralized with minus.
Question 18
On the red-green (duochrome) test the patient reports letters on the red side are clearer. The next refinement step is to:
- A. Add cylinder power
- B. Add +0.25 sphere
- C. Add -0.25 sphere
- D. Stop — the sphere is balanced
Show answer to question 18
Answer: C. Add -0.25 sphere
RAM-GAP: Red clearer, Add Minus; Green clearer, Add Plus. Chromatic aberration puts red focus behind green, so a red-clear response means the eye needs more minus to center the focal interval on the retina.
Ophthalmic Imaging
5% of the examQuestion 19
Optical coherence tomography (OCT) produces:
- A. Cross-sectional images of retinal layers using light
- B. X-ray images of the orbit to check for metal fragments
- C. Ultrasound images of the globe through closed lids
- D. Maps of the visual field from responses to spots of light
Show answer to question 19
Answer: A. Cross-sectional images of retinal layers using light
OCT uses low-coherence interferometry to generate micron-scale cross-sections of the retina and optic nerve — noninvasive and dye-free.
Question 20
OCT angiography (OCT-A) is notable because it:
- A. Uses X-rays to outline the retinal vessels
- B. Requires double the usual fluorescein dose
- C. Shows leakage from retinal vessels
- D. Maps retinal blood flow with no dye
Show answer to question 20
Answer: D. Maps retinal blood flow with no dye
OCT-A detects motion between repeated scans — moving blood cells become the contrast agent. No IV, no nausea, no allergy risk, at the cost of a smaller field, motion sensitivity, and no view of leakage.
Medical Ethics, Legal, and Regulatory Issues
4% of the examQuestion 21
A patient's employer calls requesting a copy of the patient's eye exam results. The office may release them:
- A. If the caller sounds legitimate
- B. Whenever an employer requests, since they pay for insurance
- C. Only with the patient's written authorization
- D. After 30 days regardless
Show answer to question 21
Answer: C. Only with the patient's written authorization
Employers are not part of treatment, payment, or operations. Disclosure to them — like most third-party releases — requires the patient's signed authorization on file.
Free Medical Ethics, Legal, and Regulatory Issues study guide →
Ocular Motility Testing
4% of the examQuestion 22
The lateral rectus muscle is innervated by which cranial nerve?
- A. III (oculomotor)
- B. VI (abducens)
- C. IV (trochlear)
- D. VII (facial)
Show answer to question 22
Answer: B. VI (abducens)
LR6-SO4-3: lateral rectus — CN VI; superior oblique — CN IV; all other extraocular muscles — CN III.
Lensometry
3% of the examQuestion 23
While neutralizing a lens, both sets of mires come into sharp focus at a single power-drum reading. The lens is:
- A. A high-cylinder lens
- B. Spherical, with no cylinder
- C. A prism-compensated lens
- D. Out of calibration
Show answer to question 23
Answer: B. Spherical, with no cylinder
A sphere focuses all meridians at one power, so sphere and cylinder mire lines clear together. A spherocylindrical lens needs two different drum readings, one for each principal meridian.
Biometry
3% of the examQuestion 24
An axial length error of 1.0 mm changes the postoperative refraction by approximately:
- A. 0.25 to 0.5 diopter
- B. 10 to 12 diopters
- C. 2.5 to 3 diopters
- D. 6 to 7 diopters
Show answer to question 24
Answer: C. 2.5 to 3 diopters
The commonly taught rule of thumb: each millimeter of axial-length error shifts the outcome roughly 2.5–3 D, which is why careful, repeatable biometry technique matters.
Supplemental Testing
3% of the examQuestion 25
Central corneal thickness is measured with:
- A. A keratometer
- B. A pachymeter
- C. A lensometer
- D. A perimeter
Show answer to question 25
Answer: B. A pachymeter
Pachymetry (ultrasonic or optical) measures corneal thickness. It matters clinically because thin corneas underestimate applanation IOP and are an independent glaucoma risk factor.
Surgical Assisting
3% of the examQuestion 26
The antiseptic most commonly used to prep periocular skin and the ocular surface is:
- A. Chlorhexidine gluconate
- B. Isopropyl alcohol
- C. Povidone-iodine
- D. Hydrogen peroxide
Show answer to question 26
Answer: C. Povidone-iodine
Dilute povidone-iodine is the standard ophthalmic prep and demonstrably lowers endophthalmitis risk. Chlorhexidine and alcohol are avoided near the eye because they damage the corneal epithelium.
Keratometry
2% of the examQuestion 27
K readings are 44.00 D at 090 and 42.00 D at 180. The vertical meridian is:
- A. Flatter, with a longer radius of curvature
- B. Equal in curvature to the horizontal
- C. Steeper, with a shorter radius of curvature
- D. Impossible to compare from these numbers
Show answer to question 27
Answer: C. Steeper, with a shorter radius of curvature
Higher dioptric power means a more steeply curved surface, and curvature and radius are inverse — the 44.00 D meridian is the steeper one. The 2 D difference is corneal astigmatism.
Diagnostic Ultrasound
2% of the examQuestion 28
A coupling gel (or fluid immersion) is required for ocular ultrasound because sound waves:
- A. Travel too quickly through water
- B. Are blocked by the eyelids
- C. Damage the cornea without lubrication
- D. Do not transmit well through air
Show answer to question 28
Answer: D. Do not transmit well through air
An air gap reflects nearly all the sound energy before it reaches the eye. Gel or immersion fluid gives the beam a continuous medium, so echoes return from ocular structures instead of the probe tip.
Microbiology
2% of the examQuestion 29
The organism classically responsible for rapidly destructive contact-lens-related keratitis is:
- A. Pseudomonas aeruginosa
- B. Staphylococcus epidermidis
- C. Candida albicans
- D. Adenovirus
Show answer to question 29
Answer: A. Pseudomonas aeruginosa
Pseudomonas loves lens cases and thrives in the hypoxic environment under a lens, and it can melt a cornea in a day. It's why the painful red eye in a lens wearer is a same-day emergency.
Optics and Spectacles
2% of the examQuestion 30
Transpose -1.00 -1.00 x 180 to plus-cylinder form:
- A. -2.00 +1.00 x 180
- B. -1.00 +1.00 x 180
- C. 0.00 +1.00 x 090
- D. -2.00 +1.00 x 090
Show answer to question 30
Answer: D. -2.00 +1.00 x 090
Same three steps in either direction: add sphere and cylinder (-1.00 + -1.00 = -2.00), flip the cylinder sign (+1.00), rotate the axis 90° (180 → 090).
Contact Lenses
2% of the examQuestion 31
Contact lenses and their cases should never come in contact with:
- A. Fresh multipurpose solution
- B. Tap water
- C. Daily cleaner
- D. Sterile saline used as directed
Show answer to question 31
Answer: B. Tap water
Tap (and lake or well) water carries Acanthamoeba, which causes a devastating, hard-to-treat keratitis. Lenses are cleaned and stored only in fresh disinfecting solutions — never rinsed in water or worn swimming.
Equipment Maintenance and Repair
2% of the examQuestion 32
The slit lamp is best described as a:
- A. Binocular biomicroscope for the anterior segment
- B. Camera for photographing the retina and optic disc
- C. Device for measuring the curvature of the cornea
- D. Projector for displaying distance acuity charts
Show answer to question 32
Answer: A. Binocular biomicroscope for the anterior segment
The slit lamp is a biomicroscope with a slit illumination system, used to examine lids, conjunctiva, cornea, anterior chamber, iris, and lens — and the fundus with auxiliary lenses.
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