Ocular imaging and tests Flashcards
(26 cards)
What is ocular imaging?
An integral part of ophthalmic departments that records clinical ocular examination findings in an objective, reproducible, transmissible, and durable manner.
Name four common ocular imaging techniques.
- Optical coherence tomography
- Ultrasonography
- Retinal imaging (Fundus photography)
- Fluorescein angiography
What does Optical Coherence Tomography (OCT) provide?
A cross-sectional image of the anterior eye and retina in-vivo with high resolution.
What does OCT allow for in terms of retinal assessment?
- Detection of morphological changes in the retina
- Measurement of retinal thickness
- Measurement of retinal volume
- Measurement of retinal nerve fiber layer thickness (RNFL)
- Assessment of various parameters of the optic nerve head (ONH)
What type of energy does ultrasonography use?
Acoustic energy with frequencies above the audible limit.
What are the two types of ultrasound used in ocular imaging?
- A scan
- B scan
What is the purpose of an A scan?
Produces a graphical output of echo amplitude vs distance in the eye.
Indications for A scan include measuring what?
- Anterior chamber depth
- Axial length of the eye
What does a B scan produce?
Cross-sectional images of the orbital and ocular tissues.
List three indications for B scan.
- Retinal detachments
- Orbital tumors
- Dense cataracts
What is the purpose of retinal imaging or fundus photography?
Acquires color photographs of the retina for long-term patient monitoring.
What does fluorescein angiography assess?
Choroidal and retinal vessels using intravenous fluorescein dye.
What is sodium fluorescein?
A water-soluble dye used in fluorescein angiography that binds to serum proteins.
What is an absolute contraindication for fluorescein angiography?
Fluorescein allergy.
What indications are there for fluorescein angiography?
- Diabetic retinopathy
- Age-related macular degeneration
- Central retinal vein occlusion
- Hypertensive retinopathy
What is the main advantage of indocyanine green angiography over fluorescein angiography?
Provides better resolution of the choroidal circulation.
What imaging technique employs X-rays to produce images?
Computed tomography (CT) scan.
What are the main uses of CT in ocular imaging?
- Suspected trauma
- Intraocular foreign body
- Evaluation of orbital infections
What is a caution associated with CT scans?
Increased risk of cancer with repeated examinations.
What does MRI use to produce images?
A powerful magnet, radio waves, and movement of protons.
What are the indications for MRI in ocular imaging?
- Intracranial aneurysm
- Optic nerve disease
- Retrobulbar neuritis
What does tonometry measure?
Intraocular pressure.
What device is used during tonometry?
A tonometer.
What is perimetry?
A visual field test that maps the complete field of vision.
