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Retina and Vitreous > Retinal Anatomy, Physiology, and Diagnostic Approaches > Flashcards

Retinal Anatomy, Physiology, and Diagnostic Approaches Flashcards

1
Q

composition of vitreous gel

A

water, collagen, and hyaluronic acid

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2
Q

vitreous base location

A

2mm anterior to and 4 mm posterior to the ora serrata

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3
Q

histologic definition of macula

A

2 or more layers of ganglion cells

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4
Q

borders of perifovea, parafovea, fovea, foveola

A
  • foveola: central 0.35mm, contains cones only
  • fovea: 1.5mm
  • parafovea: 0.5mm ring around fovea
  • perifovea: 1.5mm ring around parafovea
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5
Q

location of fovea to disc

A

temporal and slightly inferior

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6
Q

layers of retina

A

ILM, NFL, GCL, IPL, INL, OPL, ONL, ELM, photoreceptors

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7
Q

ora bay

dentate process

A

posterior extensions of pars plana

jetties of retinal tissue extending in between ora bays

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8
Q

ellipsoid line

myoid line

A

mitochondria of photoreceptors

endoplasmic reticulum of photoreceptors

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9
Q

relation of rods and cones to bipolar cells, respectively

A

cones have 1:1 synapses

multiple rods synapse on one bipolar cell

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10
Q

what is the ILM made up of

A

footplate of Muller cells

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11
Q

XLM

A

zonular attachments between photoreceptors and Muller cells

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12
Q

retinal RPE is contiguous with ____

A

pigmented epithelium of ciliary body and iris

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13
Q

functions of RPE

A

absorbs light, phagocytoses rod and cone outer segments, maintains subretinal space, forms scar tissue, retinal and fatty acid metabolism, forms outer blood-ocular barrier

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14
Q

layers of Bruch membrane

A 
Basement membrane of RPE
Collagenous zone, inner
Elastic fibers
Collagenous zone, outer
Basement membrane of endothelium of choriocapillaris

(Bread-cheese-egg-cheese-bread)

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15
Q

role of RPE in visual pigment metabolism

A

regeneration of 11-cis-retinaldehyde from 11-trans-retinaldehyde

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16
Q

from where does blood enter the choroid

A

posterior ciliary arteries

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17
Q

hydrophobic or hydrophilic:
corneal epithelium
corneal stroma
sclera

A

hydrophobic
hydrophilic
hydrophilic

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18
Q

magnification of direct ophthalmoscope? indirect?

A

15 x

2-5 x

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19
Q

How is image generated in:

  1. scanning laser ophthalmoscopy (SLO)
  2. optical coherence tomography
  3. fundus autofluorescence
A
  1. near infrared light rapidly sweeps back and forth across retina (used in FA and ICG)
  2. captured reflected light
  3. uses SLO or camera with excitation filter; images intrinsic fluorescence emitted by a substance after excitation
20
Q

predominant source of autofluorescence in retina

A

lipofuscin

21
Q

how does fluorescein circulate in blood?

ICG?

A

80% protein-bound (mostly albumin), 20% free

98% protein-bound

22
Q

wavelength of light that excites fluorescein? wavelength of fluorescence?

A

blue (465-490)

green (520-530)

23
Q

time for fluorescein to enter:
ophthalmic artery/choroid
arterial phase
arteriovenous phase

A

8-12 seconds
18-27 seconds
1 minute

24
Q

types of hypo- and hyper-fluorescence

A

hypo:

  • blocking (by fibrous tissue, blood, pigment)
  • vascular filling defect (eg. BRAO)

hyper:

  • leakage (gradual seepage across RPE causing blurred margins, as in CNV, DME, IRMA)
  • staining (increase but with clear borders; scar, drusen)
  • window defect (hole in RPE shows right through to choroid)
  • pooling (accumulation in fluid-filled space, like PED)
  • autofluorescence (lipofuscin)
25
side effects of fluorescein
- all patients have yellowing of skin and conj that lasts 6-12 hours - most common: nausea/vagal response (10%) - urticaria (1%) - anaphylaxis (1/100,000) - extravasation with tissue necrosis (rare)
26
relative contraindications to ICG
iodide or shellfish allergy, Metformin, and liver disease (metabolized by liver)
27
a wave of ERG | b wave of ERG
- initial corneal negative reflection, generated by rods and cones - corneal positive reflection, generated by inner retina, predominantly Muller cells and ON bipolar cells
28
normal a wave and reduced b wave (electronegative)
- diseased inner retina with normal photoreceptors | - congenital stationary night blindness, CRVO, CRAO, juvenile x-linked retinoschisis, MAR
29
diffusely reduced a and b waves but not extinguished
early RP, old chorioretinitis, RD, media opacity, high myopia
30
newborn ERG?
blunted waveforms
31
in general in ERG, time-delay signifies _____ and decreased amplitude signifies
generalized dysfunction | sectoral dysfunction
32
absent or impaired photopic response, normal scotopic response
primary cone problem: | cone and cone-rod dystrophies, achromatopsia
33
supra-normal ERG
albinism (less pigment to absorb light and blunt response)
34
What do the following represent: 1. DA 0.01 2. DA 3.0 3. DA 10.0/30.0 4. LA 3.0 5. LA 3.0 30 Hz
1. inner segments corresponding to rods (b wave but no a wave) 2. mixed rod-cone; see above 3. combined inner and outer segments with both a and b waves. normal a wave and blunted b wave = negative ERG and localizes dysfunction to inner retina 4. Photopic flash: a wave specific for cones and their bipolar cells. 5. Photopic flicker: specific for cones but no anatomic specification (could be inner or outer dysfunction)
35
ERG measures ___ | EOG measures ___
mass electrical response of the retina | electrical potential across RPE
36
what does the Arden ratio represent and what is a normal value?
ratio of light peak to dark trough in EOG. normal is greater than 1.7 (170%)
37
timing of retinal response in ERG is best assessed by which component?
30 Hz flicker
38
T or F: most cones reside in the macula
False. Macula is more cone-dense, but larger amount of cones still reside outside macula
39
normal ERG, abnormal EOG?
Best disease
40
clinical use of VEP?
optic nerve conduction delay (optic neuritis), rule out malingering
41
3 types of cones
short (blue), medium (green), and long (red)
42
protan v deutan red-green color deficiency
protan: deficient long wavelength cones (red) deutan: deficient short wavelength cones (green)
43
general significance of blue-yellow color deficiency?
rarely inherited, usually a sign of acquired disease (like glaucoma)
44
most accurate assessment of red-green color defects
anomaloscope
45
What color deficiencies do HRR and Ishihara plates assess for?
HRR: protan (red), deutan (green), and tritan (blue) Ishihara: only protan and deutan

Retina and Vitreous (6 decks)

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