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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
Q

side effects of fluorescein

A
  • 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
Q

relative contraindications to ICG

A

iodide or shellfish allergy, Metformin, and liver disease (metabolized by liver)

27
Q

a wave of ERG

b wave of ERG

A
  • initial corneal negative reflection, generated by rods and cones
  • corneal positive reflection, generated by inner retina, predominantly Muller cells and ON bipolar cells
28
Q

normal a wave and reduced b wave (electronegative)

A
  • diseased inner retina with normal photoreceptors

- congenital stationary night blindness, CRVO, CRAO, juvenile x-linked retinoschisis, MAR

29
Q

diffusely reduced a and b waves but not extinguished

A

early RP, old chorioretinitis, RD, media opacity, high myopia

30
Q

newborn ERG?

A

blunted waveforms

31
Q

in general in ERG, time-delay signifies _____ and decreased amplitude signifies

A

generalized dysfunction

sectoral dysfunction

32
Q

absent or impaired photopic response, normal scotopic response

A

primary cone problem:

cone and cone-rod dystrophies, achromatopsia

33
Q

supra-normal ERG

A

albinism (less pigment to absorb light and blunt response)

34
Q

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
A
  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
Q

ERG measures ___

EOG measures ___

A

mass electrical response of the retina

electrical potential across RPE

36
Q

what does the Arden ratio represent and what is a normal value?

A

ratio of light peak to dark trough in EOG. normal is greater than 1.7 (170%)

37
Q

timing of retinal response in ERG is best assessed by which component?

A

30 Hz flicker

38
Q

T or F: most cones reside in the macula

A

False. Macula is more cone-dense, but larger amount of cones still reside outside macula

39
Q

normal ERG, abnormal EOG?

A

Best disease

40
Q

clinical use of VEP?

A

optic nerve conduction delay (optic neuritis), rule out malingering

41
Q

3 types of cones

A

short (blue), medium (green), and long (red)

42
Q

protan v deutan red-green color deficiency

A

protan: deficient long wavelength cones (red)
deutan: deficient short wavelength cones (green)

43
Q

general significance of blue-yellow color deficiency?

A

rarely inherited, usually a sign of acquired disease (like glaucoma)

44
Q

most accurate assessment of red-green color defects

A

anomaloscope

45
Q

What color deficiencies do HRR and Ishihara plates assess for?

A

HRR: protan (red), deutan (green), and tritan (blue)
Ishihara: only protan and deutan

Retina and Vitreous (6 decks)

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