COT Ophthalmic Imaging and Photography 5 — Questions and Answers
Question 1: A photographer notices the fundus image has a crescent-shaped dark shadow on one edge. The most likely cause is:
- Patient's eyelid partially covering the pupil (Correct answer)
- Incorrect focus setting on the camera
- Insufficient flash power
- Corneal edema obscuring the image
Correct answer: Patient's eyelid partially covering the pupil
A crescent-shaped shadow (eyelid artifact) occurs when the patient's upper or lower eyelid partially occludes the pupil during image capture.
Question 2: Stereo fundus photography achieves a three-dimensional view by:
- Using polarized filters to separate left and right eye images
- Capturing two images from slightly different angles through the same pupil (Correct answer)
- Increasing the flash power to improve depth of field
- Applying digital post-processing to a single flat image
Correct answer: Capturing two images from slightly different angles through the same pupil
Stereo fundus photography captures two sequential images with the camera decentered slightly left and right, simulating binocular parallax for 3D viewing.
Question 3: In OCT imaging, 'shadow artifact' beneath a retinal vessel is caused by:
- Absorption and scattering of the OCT beam by blood blocking deeper signal (Correct answer)
- Specular reflection from the ILM
- Saccadic eye movement during scanning
- Incorrect polarization of the reference beam
Correct answer: Absorption and scattering of the OCT beam by blood blocking deeper signal
Blood in retinal vessels strongly absorbs and scatters the OCT beam, producing a dark (hyporeflective) shadow beneath the vessel in the scan.
Question 4: Which imaging modality is considered the gold standard for diagnosing choroidal neovascularization (CNV) location and activity in wet AMD?
- B-scan ultrasonography
- Fluorescein angiography (Correct answer)
- Infrared reflectance imaging
- Fundus autofluorescence
Correct answer: Fluorescein angiography
Fluorescein angiography remains the gold standard for characterizing CNV type (classic vs. occult), boundaries, and activity to guide anti-VEGF treatment decisions.
Question 5: The Specular microscope measures which property of the corneal endothelium?
- Endothelial cell density and morphology (Correct answer)
- Corneal curvature and astigmatism
- Anterior chamber depth
- Corneal pachymetry only
Correct answer: Endothelial cell density and morphology
Specular microscopy analyzes the reflected image of the endothelial cell mosaic to measure cell density (cells/mm²), cell size variation (CV), and hexagonality.
Question 6: When performing B-scan ultrasonography on a patient with dense vitreous hemorrhage, the primary clinical goal is to:
- Measure axial length for IOL calculation
- Rule out retinal detachment or posterior segment pathology hidden by the hemorrhage (Correct answer)
- Assess crystalline lens transparency
- Map corneal topography
Correct answer: Rule out retinal detachment or posterior segment pathology hidden by the hemorrhage
B-scan US penetrates media opacities like dense hemorrhage, allowing the examiner to evaluate retinal attachment and detect posterior pathology when direct visualization is impossible.
Question 7: The recommended patient position for obtaining a reliable and reproducible Goldmann visual field test during documentation is:
- Reclined at 45° to reduce head movement
- Upright with chin and forehead resting firmly in the bowl rest (Correct answer)
- Standing with one eye patched
- Seated with the head tilted 15° toward the tested eye
Correct answer: Upright with chin and forehead resting firmly in the bowl rest
The patient should sit upright with their chin and forehead positioned firmly against the bowl rests to stabilize the head and maintain consistent eye position throughout the test.
COT Ophthalmic Imaging and Photography 5
A photographer notices the fundus image has a crescent-shaped dark shadow on one edge.
The most likely cause is: