Certified Ophthalmic Assistant| 189
Questions| WITH COMPLETE SOLUTIONS
Course
COA
1. Anatomy & Physiology
Q1: What structure in the eye is responsible for maintaining intraocular pressure (IOP)?
A: Aqueous humor, produced by the ciliary body, maintains IOP.
Explanation:
The ciliary processes of the ciliary body produce aqueous humor. This fluid circulates from the
posterior chamber through the pupil to the anterior chamber and drains via the trabecular
meshwork into Schlemm’s canal. Aqueous production and drainage balance determine IOP.
Elevated IOP is a key risk factor in glaucoma.
2. Optics & Refraction
Q2: A patient has a manifest refraction of -2.00 -1.00 x 180. What is the spherical equivalent?
A: -2.50 D
Solution:
Spherical equivalent = Sphere + ½ Cylinder
= -2.00 + ½(-1.00)
= -2.00 - 0.50 = -2.50 D
3. Pharmacology
Q3: Which drug class does tropicamide belong to and what is its primary clinical use?
A: Anticholinergic; used for pupil dilation (mydriasis)
Explanation:
Tropicamide blocks muscarinic receptors in the iris sphincter muscle → pupil dilation. It is
short-acting, making it useful in routine dilated fundus exams. It may slightly impair
accommodation.
4. Patient Care
,Q4: A patient reports flashing lights and floaters. What is the most appropriate response?
A: Notify the ophthalmologist immediately for urgent evaluation.
Explanation:
Flashes and floaters can indicate a retinal tear or detachment. These are vision-threatening
emergencies. COAs must recognize red-flag symptoms and initiate proper triage without delay.
5. Lensometry
Q5: A lensometer reads: -1.50 D sphere, with the axis line at 90°. Then, when the cylinder wheel
is turned, an additional -0.50 D is needed to bring the second set of lines into focus. What is the
full lens prescription?
A: -1.50 -0.50 x 90
Explanation:
First power = sphere = -1.50
Second power = cylinder = -0.50
Axis is read from the scale = 90
So, full prescription: -1.50 -0.50 x 90
6. Visual Acuity
Q6: If a patient sees 20/100 with their glasses and 20/25 with pinhole, what is the likely cause of
reduced vision?
A: Refractive error
Explanation:
A pinhole test reduces the effect of refractive error by only allowing central rays to enter the eye.
If vision improves with pinhole, uncorrected refractive error (like myopia, hyperopia,
astigmatism) is likely.
7. Tonometry
Q7: What is the principle behind Goldmann applanation tonometry?
A: It measures IOP based on the Imbert-Fick law.
Explanation:
The Imbert-Fick law assumes a dry, flexible sphere: pressure = force / area. Goldmann
tonometry measures the force needed to flatten a 3.06 mm area of cornea. Fluorescein and cobalt
blue light are used to visualize the tear film during measurement.
,8. Visual Fields
Q8: A patient with bitemporal hemianopia likely has a lesion at what anatomical site?
A: Optic chiasm
Explanation:
At the optic chiasm, nasal retinal fibers (responsible for temporal visual fields) cross. A lesion
(e.g., pituitary tumor) here can cause loss of temporal vision in both eyes — bitemporal
hemianopia.
9. Contact Lenses
Q9: What is the most common complication of extended wear contact lenses?
A: Corneal hypoxia
Explanation:
Extended wear lenses can reduce oxygen supply to the cornea, leading to hypoxia. This may
cause neovascularization, edema, or even infection. Proper wear schedule and lens material
selection help mitigate this.
10. Slit Lamp Examination
Q10: During a slit lamp exam, what structure is examined using a narrow, high-intensity beam
angled at 45° to the cornea?
A: Anterior chamber for cells and flare
Explanation:
Using optical sectioning at an angle allows visualization of particles in the aqueous. Cells
(white blood cells) and flare (protein leakage) indicate inflammation, as in anterior uveitis.
11. Q: What part of the eye is primarily responsible for focusing light on the retina?
A: The cornea
Explanation:
The cornea provides approximately 2/3 of the eye's refractive power. While the lens fine-tunes
focus, the cornea is the dominant focusing structure.
12. Q: A patient is using timolol eye drops. What condition is most likely being treated?
, A: Glaucoma
Explanation:
Timolol is a beta-blocker that decreases aqueous humor production to lower intraocular
pressure. It is commonly prescribed for open-angle glaucoma.
13. Q: What is the correct order of performing the following tests: visual acuity, tonometry,
dilation?
A: Visual acuity → tonometry → dilation
Explanation:
Visual acuity must be done first to assess baseline vision without drug interference.
Tonometry must be done before dilation, as pupil dilation can affect IOP readings.
Dilation comes last for a comprehensive fundus exam.
14. Q: What is the main function of the retina?
A: To convert light into electrical signals
Explanation:
The retina contains photoreceptors (rods and cones) that transform light into neural signals sent
via the optic nerve to the brain.
15. Q: What instrument is used to measure corneal curvature?
A: Keratometer
Explanation:
A keratometer (ophthalmometer) measures the anterior corneal curvature, used for contact lens
fitting and astigmatism evaluation.
16. Q: A visual acuity of 20/200 means:
A: The patient can see at 20 feet what a normal person sees at 200 feet.
Explanation:
The top number = testing distance; bottom number = distance at which a person with normal
vision can see the same object clearly. 20/200 is legally blind (with correction).
Questions| WITH COMPLETE SOLUTIONS
Course
COA
1. Anatomy & Physiology
Q1: What structure in the eye is responsible for maintaining intraocular pressure (IOP)?
A: Aqueous humor, produced by the ciliary body, maintains IOP.
Explanation:
The ciliary processes of the ciliary body produce aqueous humor. This fluid circulates from the
posterior chamber through the pupil to the anterior chamber and drains via the trabecular
meshwork into Schlemm’s canal. Aqueous production and drainage balance determine IOP.
Elevated IOP is a key risk factor in glaucoma.
2. Optics & Refraction
Q2: A patient has a manifest refraction of -2.00 -1.00 x 180. What is the spherical equivalent?
A: -2.50 D
Solution:
Spherical equivalent = Sphere + ½ Cylinder
= -2.00 + ½(-1.00)
= -2.00 - 0.50 = -2.50 D
3. Pharmacology
Q3: Which drug class does tropicamide belong to and what is its primary clinical use?
A: Anticholinergic; used for pupil dilation (mydriasis)
Explanation:
Tropicamide blocks muscarinic receptors in the iris sphincter muscle → pupil dilation. It is
short-acting, making it useful in routine dilated fundus exams. It may slightly impair
accommodation.
4. Patient Care
,Q4: A patient reports flashing lights and floaters. What is the most appropriate response?
A: Notify the ophthalmologist immediately for urgent evaluation.
Explanation:
Flashes and floaters can indicate a retinal tear or detachment. These are vision-threatening
emergencies. COAs must recognize red-flag symptoms and initiate proper triage without delay.
5. Lensometry
Q5: A lensometer reads: -1.50 D sphere, with the axis line at 90°. Then, when the cylinder wheel
is turned, an additional -0.50 D is needed to bring the second set of lines into focus. What is the
full lens prescription?
A: -1.50 -0.50 x 90
Explanation:
First power = sphere = -1.50
Second power = cylinder = -0.50
Axis is read from the scale = 90
So, full prescription: -1.50 -0.50 x 90
6. Visual Acuity
Q6: If a patient sees 20/100 with their glasses and 20/25 with pinhole, what is the likely cause of
reduced vision?
A: Refractive error
Explanation:
A pinhole test reduces the effect of refractive error by only allowing central rays to enter the eye.
If vision improves with pinhole, uncorrected refractive error (like myopia, hyperopia,
astigmatism) is likely.
7. Tonometry
Q7: What is the principle behind Goldmann applanation tonometry?
A: It measures IOP based on the Imbert-Fick law.
Explanation:
The Imbert-Fick law assumes a dry, flexible sphere: pressure = force / area. Goldmann
tonometry measures the force needed to flatten a 3.06 mm area of cornea. Fluorescein and cobalt
blue light are used to visualize the tear film during measurement.
,8. Visual Fields
Q8: A patient with bitemporal hemianopia likely has a lesion at what anatomical site?
A: Optic chiasm
Explanation:
At the optic chiasm, nasal retinal fibers (responsible for temporal visual fields) cross. A lesion
(e.g., pituitary tumor) here can cause loss of temporal vision in both eyes — bitemporal
hemianopia.
9. Contact Lenses
Q9: What is the most common complication of extended wear contact lenses?
A: Corneal hypoxia
Explanation:
Extended wear lenses can reduce oxygen supply to the cornea, leading to hypoxia. This may
cause neovascularization, edema, or even infection. Proper wear schedule and lens material
selection help mitigate this.
10. Slit Lamp Examination
Q10: During a slit lamp exam, what structure is examined using a narrow, high-intensity beam
angled at 45° to the cornea?
A: Anterior chamber for cells and flare
Explanation:
Using optical sectioning at an angle allows visualization of particles in the aqueous. Cells
(white blood cells) and flare (protein leakage) indicate inflammation, as in anterior uveitis.
11. Q: What part of the eye is primarily responsible for focusing light on the retina?
A: The cornea
Explanation:
The cornea provides approximately 2/3 of the eye's refractive power. While the lens fine-tunes
focus, the cornea is the dominant focusing structure.
12. Q: A patient is using timolol eye drops. What condition is most likely being treated?
, A: Glaucoma
Explanation:
Timolol is a beta-blocker that decreases aqueous humor production to lower intraocular
pressure. It is commonly prescribed for open-angle glaucoma.
13. Q: What is the correct order of performing the following tests: visual acuity, tonometry,
dilation?
A: Visual acuity → tonometry → dilation
Explanation:
Visual acuity must be done first to assess baseline vision without drug interference.
Tonometry must be done before dilation, as pupil dilation can affect IOP readings.
Dilation comes last for a comprehensive fundus exam.
14. Q: What is the main function of the retina?
A: To convert light into electrical signals
Explanation:
The retina contains photoreceptors (rods and cones) that transform light into neural signals sent
via the optic nerve to the brain.
15. Q: What instrument is used to measure corneal curvature?
A: Keratometer
Explanation:
A keratometer (ophthalmometer) measures the anterior corneal curvature, used for contact lens
fitting and astigmatism evaluation.
16. Q: A visual acuity of 20/200 means:
A: The patient can see at 20 feet what a normal person sees at 200 feet.
Explanation:
The top number = testing distance; bottom number = distance at which a person with normal
vision can see the same object clearly. 20/200 is legally blind (with correction).
