CERTIFIED OPHTHALMIC ASSISTANT
(COA) PRACTICE TEST 2026/2027
QUESTIONS AND ANSWERS
1. Which of the following represents the correct order of the corneal layers from anterior to
posterior?
A. Epithelium, Stroma, Bowman’s layer, Descemet’s membrane, Endothelium
B. Epithelium, Bowman’s layer, Stroma, Endothelium, Descemet’s membrane
C. Endothelium, Descemet’s membrane, Stroma, Bowman’s layer, Epithelium
D. Epithelium, Bowman’s layer, Stroma, Descemet’s membrane, Endothelium
Answer: D
Conceptual Explanation: The cornea consists of five main layers: the epithelium
(outermost), Bowman’s layer, the stroma (thickest layer), Descemet’s membrane, and the
endothelium (innermost).
2. A patient with a ‘Marcus Gunn’ pupil has which of the following conditions?
A. Anisocoria
B. Adie’s tonic pupil
C. Relative Afferent Pupillary Defect (RAPD)
,D. Argyll Robertson pupil
Answer: C
Conceptual Explanation: A Marcus Gunn pupil is another name for a Relative Afferent
Pupillary Defect (RAPD), where the affected eye’s pupil fails to constrict normally when
light is swung from the healthy eye to the affected eye.
3. When performing Goldmann applanation tonometry, what is the standard diameter of the
area of the cornea flattened by the prism?
A. 2.06 mm
B. 4.06 mm
C. 3.06 mm
D. 5.06 mm
Answer: C
Conceptual Explanation: The Goldmann applanation tonometer is designed to flatten a
corneal area of 3.06 mm in diameter, which correlates the force applied to the intraocular
pressure.
4. Which instrument is used primarily to measure the curvature of the central cornea?
A. Keratometer
B. Tonometer
C. Lensometer
, D. Pachymeter
Answer: A
Conceptual Explanation: A keratometer (or ophthalmometer) measures the curvature of
the anterior surface of the cornea, specifically the central 3mm, used for contact lens fitting
and IOL calculations.
5. A patient complains of sudden flashes of light and new floaters in their vision. This most
likely indicates:
A. Cataract formation
B. Posterior Vitreous Detachment or Retinal Tear
C. Glaucoma flare-up
D. Macular Degeneration
Answer: B
Conceptual Explanation: Photopsia (flashes) and floaters are classic symptoms of
vitreous traction on the retina, which can lead to a retinal tear or detachment.
6. Transpose the following prescription to Minus Cylinder form: +2.00 +1.50 x 090
A. +0.50 -1.50 x 180
B. +2.00 -1.50 x 180
C. +3.50 -1.50 x 090
D. +3.50 -1.50 x 180
(COA) PRACTICE TEST 2026/2027
QUESTIONS AND ANSWERS
1. Which of the following represents the correct order of the corneal layers from anterior to
posterior?
A. Epithelium, Stroma, Bowman’s layer, Descemet’s membrane, Endothelium
B. Epithelium, Bowman’s layer, Stroma, Endothelium, Descemet’s membrane
C. Endothelium, Descemet’s membrane, Stroma, Bowman’s layer, Epithelium
D. Epithelium, Bowman’s layer, Stroma, Descemet’s membrane, Endothelium
Answer: D
Conceptual Explanation: The cornea consists of five main layers: the epithelium
(outermost), Bowman’s layer, the stroma (thickest layer), Descemet’s membrane, and the
endothelium (innermost).
2. A patient with a ‘Marcus Gunn’ pupil has which of the following conditions?
A. Anisocoria
B. Adie’s tonic pupil
C. Relative Afferent Pupillary Defect (RAPD)
,D. Argyll Robertson pupil
Answer: C
Conceptual Explanation: A Marcus Gunn pupil is another name for a Relative Afferent
Pupillary Defect (RAPD), where the affected eye’s pupil fails to constrict normally when
light is swung from the healthy eye to the affected eye.
3. When performing Goldmann applanation tonometry, what is the standard diameter of the
area of the cornea flattened by the prism?
A. 2.06 mm
B. 4.06 mm
C. 3.06 mm
D. 5.06 mm
Answer: C
Conceptual Explanation: The Goldmann applanation tonometer is designed to flatten a
corneal area of 3.06 mm in diameter, which correlates the force applied to the intraocular
pressure.
4. Which instrument is used primarily to measure the curvature of the central cornea?
A. Keratometer
B. Tonometer
C. Lensometer
, D. Pachymeter
Answer: A
Conceptual Explanation: A keratometer (or ophthalmometer) measures the curvature of
the anterior surface of the cornea, specifically the central 3mm, used for contact lens fitting
and IOL calculations.
5. A patient complains of sudden flashes of light and new floaters in their vision. This most
likely indicates:
A. Cataract formation
B. Posterior Vitreous Detachment or Retinal Tear
C. Glaucoma flare-up
D. Macular Degeneration
Answer: B
Conceptual Explanation: Photopsia (flashes) and floaters are classic symptoms of
vitreous traction on the retina, which can lead to a retinal tear or detachment.
6. Transpose the following prescription to Minus Cylinder form: +2.00 +1.50 x 090
A. +0.50 -1.50 x 180
B. +2.00 -1.50 x 180
C. +3.50 -1.50 x 090
D. +3.50 -1.50 x 180
