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Preclinical Optometry > Slit Lamp + Gonioscopy > Flashcards

Slit Lamp + Gonioscopy Flashcards

1
Q

SL Indications

A 
REE to examine anterior segment
CL fitting and aftercare
FB removal
Anterior segment imaging
TBUT

Additional:
Tonometry
Gonioscopy
Fundus lens - posterior segment imaging

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2
Q

SL construction

A 
Galilean telescope
M: 10, 16, 25, 40x / continuous dial
Dioptre: ±6D
Slit width: 0-14mm continuous
Slit angle: 0-180deg cont.
Slit inclination (click stop): 5, 10, 15, 20deg
Filters: UV, red-free, Cobalt blue, ND
Fixed aperture diameters: 14, 10, 5, 4, 3, 1, 0.2mm
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3
Q

What is the red free filter used for?

A

Blood vs. pigment

  • BV appear darker/black cf. pigment
  • Choroidal pigment disappears (RPE overlying choroid absorbs green light)
  • Retinal pigment remains the same

RNFL: BDB pattern

Corneal or iris neovascularisation

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4
Q

What is the Cobalt blue filter used for?

A

Used in conj. with NaFl

  • damage to epithelial cells in the cornea/conjunctiva (SPK, abrasions)
  • TBUT
  • Seidel test for penetrating injury
  • Keyser Fleischer ring (keratoconus)
  • RGP fitting
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5
Q

What are the different SL techniques?

A 
Diffuse illumination for general observation
Optic section
PPD
VH / Smith method / Mod. smith method
Sclerotic scatter
Specular reflection
Retroillumination
Small spot
Lid eversion
Staining - NaFl, Lissamine green, Rose Bengal

Indirect illumination

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6
Q

What is SPK?

A

Superficial punctate keratitis

- death of small groups of cells on corneal surface

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7
Q

Describe optic section

A 
CS: IN
M: 10-16X
A: 60deg / oblique
BW: ≤ 1mm
BH: max
Illumination: max

View: corneal X-section, lens X-section, depth of lesion
Epi > endo > stroma

Gives maximum contrast

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8
Q

Describe PPD

A 
Best screening beam
CS: IN
M: 10-16X
A: 60deg / oblique
BW: 1-3mm
BH: max
Illum: med

View: corneal X-section, texture of cornea (epi & endo) and lens surfaces, depth & extent of corneal abrasion, CL fit and surface, TF, debris, FB
Stroma > epi > endo

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9
Q

Describe Sclerotic scatter

A

Position light at limbus and view opposite limbus, looking for full limbal glow (complete TIR).

CS: IN
M: 10-16X
A: 60deg / Oblique
BW: 1mm
BH: max
Illum: med

View: corneal (stromal) oedema, particles, opacities

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10
Q

Describe specular reflection

A 
CS: IN
M: 40X
A: 45deg
BW: 1-2mm
BH: max
Illum: max

View: assessment of surfaces

  • corneal epithelium & endothelium
  • corneal guttata (collagen excretions)
  • lens capsule / surface (dimpled orange texture)
  • TF quality
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11
Q

Describe retroillumination

A 
CS: IN
M: 10-16X
A: 60deg / oblique
BW: 1mm
BH: max
Illum: med

View: can view tear film/cornea (iris), iris (fundus reflection), lens opacities (fundus reflection)

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12
Q

Describe small spot

A 
CS: IN
M: >16X
A: 60deg
BW: 2mm  
BH: 1mm
Illum: max

View: anterior chamber (cells/flare), floating debris
Brightest - cornea
In b/w - AC
Other bright - lens

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13
Q

Describe lid eversion

A

Flipping the lid to look at underside of top lid

Hx: FB, CL wear, itchy eye, discharge

Signs on SL: papillae, lumps/bumps, injection, hyperaemia, blocked Meibomian glands, FB

Conducted behind SL

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14
Q

Describe staining

A

NaFl: integrity of corneal and conjunctival epithelium, TBUT, detection of papillae/follicles, ulcers, RGP fittings, Goldmann tonometry, Seidel’s sign

Rose bengal: dyes dying cells (herpes ulcers)
(stings)

Lissamine green: damaged cells, ocular surface cells unprotected by mucin
(5 mins for set in, no sting)

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15
Q

What are the SL attachments & their fx?

A
  1. Goldmann tonometer: IOP
  2. Pachymeter: CCT
  3. Camera: documentation
  4. Potential acuity measure: bypasses optics of eye to give idea of retinal function
  5. Laser: blast holes in iris to facilitate AH drainage, YAG laser
  6. Gonioscope: assess AC angle
  7. Fundus lens: assess posterior pole & VH
  8. Hruby lens
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16
Q

Indications for gonioscopy

A

VH ≤ 0.3
Shadow test 60 deg

Diagnosis, classification, management of glaucoma Px
Iris neovascularisation/retinal ischaemia (BV can leak into AC)
Iris anomalies
Raised nevus
Uveitis
Trauma (iridodialysis, angle recession, hyphema)

17
Q

Visible anatomical structures in Gonio

A 
Iris
Ciliary body
Scleral spur
TrM
Schwalbe's line
Cornea
18
Q

What is indirect illumination used for?

A 
CS: OUT
M: 10-16X
A: 60 deg / oblique
BW: 1mm
BH: max
Illum: med

View: Faint irregularities, deeper area of tissues, FB

19
Q

Van Herick

A

Same set up as optic section, only angle is always at 60deg.
Observation of ACD.

CS: IN
M: 10-16X
A: 60deg
BW: ≤ 1mm
BH: max
Illumination: max

G1: VH

20
Q

Errors with VH

A

Too far on conjunctival side / blurry = underestimation of angle

Too far on cornea side = overestimation of angle

21
Q

Shadow test

A

increases sn of VH

Shadow 0.5 = gonio

G1: very narrow/closing angle with large eclipse of distal iris due to forward bulging iris
G2: inc. eclipse of distal iris cf. G3
G3: partial shadow of distal iris
G4: open angle, good spread of light

22
Q

Explain the Smith test

A

Horizontal beam @ 60 deg
Max intensity, 1mm width
Begin with 2mm beam length and adjust until corneal and lens mires touch

Depth: 1.4x “height” measurement
Normal > 1.5mm
Depth

23
Q

Explain the modified Smith test

A 
H beam
2mm beam, illumination angle altered until mires touch
@ 60deg = 2.5mm
 60 deg = narrow
Every 5 deg = 0.25 mm
24
Q

Indications for staining

A

Dry / itchy / red / gritty / burning sensation / CL wear / discharge / watery eyes / FB / hayfever

25
Q

Aside from SL, what other ways can we examine AC?

A

OCT
Pachymetry
Ultrasound

26
Q

Advantages of Gonio lens design

A 
Indentation gonioscopy
Evaluation of angle in sitting position
High mag of angle by SL
Laser treatment of angle
Fundus & gonio view with same lens
27
Q

Disadvantages of Gonio lens design

A

Unintentional corneal indentation can open appositional occluded angle
Need viscous coupling fluid, which reduces corneal clarity
- Flange = viscous
- No flange = viscous or saline solution

28
Q

4 mirror gonio lens

A 
A: does not req. viscous medium
static & dynamic
optional flange
view 4Q / minimal rotation req.
easy removal (no suction)
superior Px comfort

D: more difficult to master
stability
view inferior to 3 mirror/flange

29
Q

3 mirror gonio lens

A

A: produces stable clear image
keeps central position
versatile: retinal examination and angle evaluation at the same time (change mirrors)

D: rotation required to view 360deg
large, invasive looking lens

  • Central Hruby lens: posterior pole, optic n’, macula
  • Trapezoid mirror is used to view the retina slightly posterior to the equator
  • Half Round mirror is used to view the peripheral retina from the equator out to the ora serrata
  • The Finger Nail mirror is used to view angle and the most
    anterior retina and ciliary body.
30
Q

6 mirror gonio lens

A

A: faster exam time with 360deg

31
Q

Gonioscopy procedure

A

Instructions
Cleaning & disinfecting gonio
Apply coupling medium to concave surface
Place P on puncta to prevent anaesthetic and viscous media reaching systemic circulation
Instil anaesthetic (1drop) each eye into conjunctival fornix
(don’t rub eyes)
Position Px comfortably against SL chin/forehead rest, align canthus marker
Illumination arm straight ahead, not blocking eyepieces
M6-16X
Vertical PPD BW, height encompasses lens diameter
Low-medium intensity (dilation = narrower angle)
Fixation target: top R ear for RE

Square orientation of lens, Px looks up, lower inferior lid and tilt lens so that it contacts the cornea
Straighten lens whilst maintaining contact
Release lids once lens is straight and in contact with the cornea

Px looks down / straight ahead also applicable

Central mirror is taken up by iris.
Top view (inferior angle) is the widest, most pigmented. I>T>N>S
V beam for I/S
H beam for N/T

32
Q

Recording for Gonio

A

Drops, [ ], time, amount, ensure no contraindications

33
Q

Contraindications for gonio

A

Anaesthetic reaction (rare)
Trauma (laceration of globe; hyphema)
Pregnancy
Corneal/conj infection/epithelial basement memb dystrophy

34
Q

When is troubleshooting required for gonio?

A
  1. Bubble in lens - tilt lens towards bubble, reinsert if large
  2. Corneal folds - ease P
  3. Blinking - hold lids, more anaesthetic req.
  4. Reflections - change incident beam angle/W/I/H
  5. Poor/no view - lens centration, illum arm not blocking
  6. No structures visible - centration, try tilting lens/corneal wedge/indentation
  7. SchW L not visible - corneal wedge (OS) to differentiate from post. TrM, reduce width, inc. intensity, offset illum
  8. Angle structures not visible - convex iris, tilt gonio away from observation mirror, if no additional struc vis = apposition
    - indent with gonio: open = apposition, closed = synechia
35
Q

Normal gonio ‘anomalies’

A

Iris processes: finger like projections that originate at periphery, bridge CB and insert into TrM

  • Prominent in childhood, wither with age
  • Diff to synechiae (inflam)

Posterior embryotoxin: prominent, anteriorly placed SchWL (10% popn)
- Also found in iridocorneal syndromes

36
Q

Gonio anomalies

A

Axenfield-Rieger syndrome: prominent Schwalbe’s line with abnormal iris processes inserting into SchWL.

High risk of glaucoma

Preclinical Optometry (14 decks)

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