OPT 210 FINAL CONTENT 2025 UPDATE WITH CORRECT
SOLUTIONS!!
What is an OCT?
noninvasive imaging technique that uses low coherence, near infrared light to capture
micrometer resolution and penetrate optical media to create cross sectional data
The light paths existing in OCT are nearly the same. What does this allow for?
high resolution
If the light wavelength of OCT is longer than visible light, what does this allow for?
ability to see through cornea, lens, vitreous, retina (translucent and even opaque
materials)
What does an OCT of the angle-anterior chamber include?
cornea, iris, angle (nasal and temporal)
What is the purpose of a single angle OCT?
-to estimate angle openness, when patient is unable to tolerate gonio
-to confirm iris approach
-can measure angle in degrees
,When performing angle OCT, what angle is considered narrow?
<15°
What is true about quality of single angle OCT?
-must include angle (where iris attaches/inserts into angle) without obstruction
-must be able to recognize structures (starting with scleral spur)
What are limitations of single angle OCT?
-can only scan 1 nasal and 1 temporal angle
-unable to visualize amount of TM pigment
-unable to visualize most abnormal findings (synechiae, neo, etc)
What are some tips to mapping an angle OCT?
-find scleral spur
-ciliary body is directly behind it
-TM is in front of scleral spur
-schwalbe's line is located on the anterior chamber side of the sclera to cornea
histological transition
-look at iris approach (specifically peripheral iris)
What is the purpose of pachymetry?
-to understand glaucoma risk and true IOP
-to measure changes in corneal thickness (edema, thinning)
,-to capture corneal foreign body
-to determine refractive surgery candidacy
-to fit hard contact lens
What is true about quality of pachymetry?
-patient must have stable tear film (consider artificial tears) and no eyelid/eyelash
obstruction of cornea (open wide, hold/tape lids)
-must have vertical skew line to ensure alignment at corneal apex
What is the purpose of an OCT of the bulbar conjunctiva/episcleral junction?
bulbar conjunctiva or episcleral lesions
In the ONH, where is the RNFL thickest?
at the disc rim followed by circumpapillary
What occurs at the cup?
RNFL axons separate to spill out to form the retina
What is thickest around the fovea?
-ganglion cell layer (50% of RGC are parafoveal)
-photoreceptor outer segments
-henle layer at perifovea; RNFL axons travel obliquely rather than horizontally
, What are examples of highly reflective structures that will block light transmission?
-blood vessels
-hemorrhages
-exudates
-pigment/RPE hyperplasia
-floaters
-media opacities
-RPE
What is the variability of OCT machines?
4-10 microns
When assessing ONH disease, where should you take an OCT?
-disc rim RNFL scan (thickness)
-circum or peripapillary RNFL scan (thickness)
-parafoveal GCL scan (thickness)
What is the ganglion cell complex?
-RNFL + GCL + IPL
When assessing macular disease, where should you take an OCT?
SOLUTIONS!!
What is an OCT?
noninvasive imaging technique that uses low coherence, near infrared light to capture
micrometer resolution and penetrate optical media to create cross sectional data
The light paths existing in OCT are nearly the same. What does this allow for?
high resolution
If the light wavelength of OCT is longer than visible light, what does this allow for?
ability to see through cornea, lens, vitreous, retina (translucent and even opaque
materials)
What does an OCT of the angle-anterior chamber include?
cornea, iris, angle (nasal and temporal)
What is the purpose of a single angle OCT?
-to estimate angle openness, when patient is unable to tolerate gonio
-to confirm iris approach
-can measure angle in degrees
,When performing angle OCT, what angle is considered narrow?
<15°
What is true about quality of single angle OCT?
-must include angle (where iris attaches/inserts into angle) without obstruction
-must be able to recognize structures (starting with scleral spur)
What are limitations of single angle OCT?
-can only scan 1 nasal and 1 temporal angle
-unable to visualize amount of TM pigment
-unable to visualize most abnormal findings (synechiae, neo, etc)
What are some tips to mapping an angle OCT?
-find scleral spur
-ciliary body is directly behind it
-TM is in front of scleral spur
-schwalbe's line is located on the anterior chamber side of the sclera to cornea
histological transition
-look at iris approach (specifically peripheral iris)
What is the purpose of pachymetry?
-to understand glaucoma risk and true IOP
-to measure changes in corneal thickness (edema, thinning)
,-to capture corneal foreign body
-to determine refractive surgery candidacy
-to fit hard contact lens
What is true about quality of pachymetry?
-patient must have stable tear film (consider artificial tears) and no eyelid/eyelash
obstruction of cornea (open wide, hold/tape lids)
-must have vertical skew line to ensure alignment at corneal apex
What is the purpose of an OCT of the bulbar conjunctiva/episcleral junction?
bulbar conjunctiva or episcleral lesions
In the ONH, where is the RNFL thickest?
at the disc rim followed by circumpapillary
What occurs at the cup?
RNFL axons separate to spill out to form the retina
What is thickest around the fovea?
-ganglion cell layer (50% of RGC are parafoveal)
-photoreceptor outer segments
-henle layer at perifovea; RNFL axons travel obliquely rather than horizontally
, What are examples of highly reflective structures that will block light transmission?
-blood vessels
-hemorrhages
-exudates
-pigment/RPE hyperplasia
-floaters
-media opacities
-RPE
What is the variability of OCT machines?
4-10 microns
When assessing ONH disease, where should you take an OCT?
-disc rim RNFL scan (thickness)
-circum or peripapillary RNFL scan (thickness)
-parafoveal GCL scan (thickness)
What is the ganglion cell complex?
-RNFL + GCL + IPL
When assessing macular disease, where should you take an OCT?
