(CDOS) Certified Diagnostic Ophthalmic Sonographer Practice Exam
(CDOS) Certified Diagnostic Ophthalmic Sonographer Practice Exam – 200
Questions & Answers
Section 1: Ocular Anatomy & Physiology (Q1–30)
Question 1
Which ocular layer contains the choroidal vasculature that supplies the outer
retina?
A) Sclera
B) Iris
C) Uvea
D) Retina
Answer: C) Uvea
Rationale: The uvea comprises the iris, ciliary body, and choroid; the choroid
provides the main blood supply to the outer retina. The sclera is the outer fibrous
layer; the retina is the innermost neural layer .
Question 2
,The average axial length of an adult human eye is closest to:
A) 16 mm
B) 22 mm
C) 24 mm
D) 28 mm
Answer: C) 24 mm
Rationale: Normal adult axial length ranges from 22–24 mm; 24 mm is often cited
as the average. Axial lengths >26.5 mm are associated with high myopia and
posterior staphyloma formation .
Question 3
What is the normal depth of the anterior chamber in an adult?
A) 0.5–1.0 mm
B) 1.0–2.0 mm
C) 2.5–3.5 mm
D) 4.0–5.0 mm
,Answer: C) 2.5–3.5 mm
Rationale: Normal adult anterior chamber depth ranges from 2.5–3.5 mm.
Shallow anterior chamber (<2.5 mm) increases the risk of angle-closure glaucoma
.
Question 4
Which of the following are components of the uveal tract? (Select all that apply)
☐ A) Iris
☐ B) Ciliary body
☐ C) Choroid
☐ D) Sclera
☐ E) Retina
Answer: A, B, C
, Rationale: The uveal tract (vascular layer) consists of the iris (anterior), ciliary
body (middle), and choroid (posterior). The sclera is the fibrous outer layer, and
the retina is the neural layer .
Question 5
The primary function of the lens in focusing light is to:
A) Provide structural support to the globe
B) Adjust focus (accommodation) in conjunction with the cornea
C) Produce aqueous humor
D) Transduce light into neural signals
Answer: B) Adjust focus (accommodation) in conjunction with the cornea
Rationale: The lens adjusts focus (accommodation) by changing shape, working in
conjunction with the cornea to direct light onto the retina. The ciliary body
produces aqueous humor, and the retina transduces light .
Question 6
The retina is divided into which two primary layers?
(CDOS) Certified Diagnostic Ophthalmic Sonographer Practice Exam – 200
Questions & Answers
Section 1: Ocular Anatomy & Physiology (Q1–30)
Question 1
Which ocular layer contains the choroidal vasculature that supplies the outer
retina?
A) Sclera
B) Iris
C) Uvea
D) Retina
Answer: C) Uvea
Rationale: The uvea comprises the iris, ciliary body, and choroid; the choroid
provides the main blood supply to the outer retina. The sclera is the outer fibrous
layer; the retina is the innermost neural layer .
Question 2
,The average axial length of an adult human eye is closest to:
A) 16 mm
B) 22 mm
C) 24 mm
D) 28 mm
Answer: C) 24 mm
Rationale: Normal adult axial length ranges from 22–24 mm; 24 mm is often cited
as the average. Axial lengths >26.5 mm are associated with high myopia and
posterior staphyloma formation .
Question 3
What is the normal depth of the anterior chamber in an adult?
A) 0.5–1.0 mm
B) 1.0–2.0 mm
C) 2.5–3.5 mm
D) 4.0–5.0 mm
,Answer: C) 2.5–3.5 mm
Rationale: Normal adult anterior chamber depth ranges from 2.5–3.5 mm.
Shallow anterior chamber (<2.5 mm) increases the risk of angle-closure glaucoma
.
Question 4
Which of the following are components of the uveal tract? (Select all that apply)
☐ A) Iris
☐ B) Ciliary body
☐ C) Choroid
☐ D) Sclera
☐ E) Retina
Answer: A, B, C
, Rationale: The uveal tract (vascular layer) consists of the iris (anterior), ciliary
body (middle), and choroid (posterior). The sclera is the fibrous outer layer, and
the retina is the neural layer .
Question 5
The primary function of the lens in focusing light is to:
A) Provide structural support to the globe
B) Adjust focus (accommodation) in conjunction with the cornea
C) Produce aqueous humor
D) Transduce light into neural signals
Answer: B) Adjust focus (accommodation) in conjunction with the cornea
Rationale: The lens adjusts focus (accommodation) by changing shape, working in
conjunction with the cornea to direct light onto the retina. The ciliary body
produces aqueous humor, and the retina transduces light .
Question 6
The retina is divided into which two primary layers?
