slit-lamp biomicroscopy module 1.4_final

SLIT-LAMP BIOMICROSCOPY Module 1.4

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Published in Australia by The International Association of Contact Lens Educators

First Edition 1997 The International Association of Contact Lens Educators 1996

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Email: [email protected]

CONTRIBUTORS

Slit-lamp Biomicroscopy Procedures:

Sylvie Sulaiman, BOptom, Mcom

Deborah Sweeney, BOptom, PhD

THE SLIT-LAMP BIOMICROSCOPE

PARTS OF A SLIT-LAMP

1. Mechanical support

2. Observation system

3. Illumination system

EXAMINING A PATIENT USING A SLIT-LAMP

SLIT-LAMP MICROSCOPE SYSTEM

Variable magnification

Binocular system

FEATURES

SLIT-LAMP MICROSCOPE

SLIT-LAMP MICROSCOPE

Low 7X - 10X General eye

Medium 20X - 25X Structure layers

High 30X - 40X Detail

General eye: Lids Bulbar conjunctiva/sclera Cornea/limbus Tears Anterior chamber/iris/crystalline lens

LOW MAGNIFICATION (7x - 10x) SLIT-LAMP BIOMICROSCOPY

SLIT-LAMP BIOMICROSCOPY


Structures:

Epithelium Stroma Endothelium Lens fit/surface

MEDIUM MAGNIFICATION (20x - 25x)


Details:

Epithelial changes

Stromal striae, folds

Endothelial folds, polymegethism

HIGH MAGNIFICATION (30x - 40x)


Epithelium

Vacuoles

Microcysts

Dystrophies



Stroma

Striae

Folds



Endothelium Polymegethism Guttata Blebs Dystrophies Cell Density


SLIT-LAMP BIOMICROSCOPY SPECULAR REFLECTION: ENDOTHELIUM

STRUCTURES OBSERVED WITH

DIFFERENT ILLUMINATIONS


Method of illumination is IMPORTANT

SLIT-LAMP ILLUMINATION SYSTEM

Variable light intensity Filters Width Height Angle

FEATURES

SLIT-LAMP ILLUMINATION SYSTEM

ILLUMINATION TECHNIQUES

Diffuse

Direct

Indirect

Retro-illumination

Specular reflection

Sclerotic scatter

Tangential

ILLUMINATION TECHNIQUES

DIFFUSE ILLUMINATION

45 degree angle between light & microscope

Slit open fully Diffusing filter Variable magnification (low to high)

BROAD BEAM

Microscope Beam of light

Cornea

Iris

DIFFUSE ILLUMINATION

Overall view of: Lids and lashes Conjunctiva Cornea Sclera Iris Pupil

DIRECT ILLUMINATION

Observation and illumination systems focused on the same point

DIRECT ILLUMINATION

Microscope

Beam of light

Iris

Cornea

DIRECT ILLUMINATION

Vary angle of illumination

Low to high magnification

Vary width and height of light source

DIRECT ILLUMINATION

Optic Section narrow, focused light

Parallelepiped wider, focused light

Conical Beam small, circular light

DIRECT ILLUMINATION OPTIC SECTION

Indicates depth localize: - nerve fibres

- blood vessels - infiltrates - cataracts

Anterior chamber angle

PRINCIPLE OF OPTIC SECTION

Aerial View

Cornea

Iris

B

A

OPTIC SECTION

A B

DIRECT ILLUMINATION

Broader view

Illuminated block of the cornea

More extensive examination

PARALLELEPIPED

PRINCIPLE OF THE PARALLELEPIPED

Iris

Cornea

Aerial View

A A'

B B'

PARALLELEPIPED

A A'

B B'

DIRECT ILLUMINATION

Inflammatory cells/flare in the anterior chamber

Darkened room

CONICAL BEAM

CONICAL BEAM

Microscope Conical beam

Cornea

Iris

Conical Beam

Beam cross-section

INDIRECT ILLUMINATION

Observation and illumination systems are not focused at the same point


Microscope

Beam of light

Cornea

Iris


Vary angle of illumination

Slit beam is offset

Vary beam width

Low to high magnification


Valuable for observing:

Epithelial vesicles Epithelial erosions Iris pathology Iris sphincter

RETRO-ILLUMINATION

Object of regard is illuminated only by reflected light

RETRO-ILLUMINATION

Microscope

Beam of light

Iris

Cornea

RETRO-ILLUMINATION

Vary angle of illumination Moderately wide beam Slit beam is offset Medium to high magnification Reflected light from iris or fundus

Observer

Transparent intra-corneal object

Background for marginal retro-illumination

Unreserved (U) and reversed (R) appearance

DIVERGING REFRACTOR

CONVERGING REFRACTOR (AFTER Brown, 1971)

U R

RETRO-ILLUMINATION

Direct Direct and full view

Indirect Adjacent

Marginal Margin or edge

TYPE ALIGNMENT

Alignment of reflected beam with area under observation

RETRO-ILLUMINATION

Valuable for observing: Vascularization Epithelial oedema Microcysts Vacuoles Dystrophies Crystalline lens opacities Contact lens deposits

SPECULAR REFLECTION

Angle of incidence equals angle of reflection

SPECULAR REFLECTION

Microscope Beam of light

Cornea

Iris

SPECULAR REFLECTION


Endothelial cell layer

Tear film debris

Tear film lipid layer thickness

SCLEROTIC SCATTER


localised epithelial oedema (CCC)

corneal scars

foreign bodies in the cornea

SCLEROTIC SCATTER

Corneal feature disclosed

SCLEROTIC SCATTER

TANGENTIAL ILLUMINATION

Large angle of 70o - 80o between

illumination and observation system


Microscope

Beam of light Cornea

Iris



Iris freckles

Tumours

General integrity of cornea and iris

FILTERED ILLUMINATION

Cobalt blue

Green (red-free)

Neutral density


Most valuable:

Cobalt blue

+ Wratten # 12



Tear layer

Ocular staining

RGP lens fitting patterns

GRATICULE

Useful for lens fitting assessment

ROUTINE EXAMINATION OF

THE EYE USING THE

SLIT-LAMP

BASELINE EXAM FLOWCHART

Lids Conjunctiva

Limbus Cornea

Tears Anterior Chamber

Iris Lens

Bulbar Palpebral

SLIT-LAMP OBSERVATIONS OF CONTACT LENS COMPLICATIONS

LID EXAMINATION

Lids redness, swelling, defects, growths,

discolouration

Puncta clear, functioning

Caruncle swollen, inflamed

CONJUNCTIVA

Redness Inflammation

LIMBUS

Redness

Neovascularization

Staining

CORNEA

Transparency

Tissue damage/insult

DETECTION OF OEDEMA

Corneal clarity

Striae/folds

Corneal thickness measurement

STRIAE

Refractile effect

Fluid separation of collagen fibrils

Minimum 5% corneal swelling

Refit with higher Dk/t lenses

CORNEAL OEDEMA vs STRIAE

0 5 10 15 20 25

25

20

15

10

5

0

Striae (number)

striae = 1.45 x oedema - 6.5 n = 192 r = 0.88 p < 0.001

(La Hood & Grant, 1990)

Oedema (%)

FOLDS

Physical buckling of Descemet's membrane and the endothelium

Minimum 8% corneal swelling

Severely compromised cornea

Immediate refit with higher Dk/t

CORNEAL OEDEMA vs STRIAE

1 Striae = 5.2% Oedema Each

= 1% Oedema additional striae

CORNEAL OEDEMA vs STRAIE

1 Fold = 7.7% Oedema Each

= 1% Oedema additional striae

CORNEAL OEDEMA vs FOLDS

0 5 10 15 20 25

25

20

15

10

5

0

Folds (number)

folds = 1.33 x oedema - 9 n = 166 r = 0.87 p < 0.001

(La Hood & Grant, 1990)

Oedema (%)

DAYTIME STRIAE RESPONSE

0 0 0

0.6

0.1

1.0

0.3

1.1

0

0.5

1

1.5

0 2 4 6

High WaterLow Water

HIGH WATER 74% vs LOW WATER 43%

Striae (Grade 0-4) (La Hood, 1991)

+5.00 D n=11

Time after lens insertion (hours)

MICROCYSTS

Small, irregular shape (15-50 m) Reversed illumination Slow onset Cyclic phenomenon Asymptomatic

MICROCYSTS DISPOSABLE HFDROGELS

0 4 8 12 16 20 24 28 32 36

50

40

30

20

10

0

Microcysts (number)

(Grant et al., 1990)

Time (months)

6-13N

DW

MICROCYSTS

Basal epithelial cells secrete intra-epithelial sheets

Disorganised cell growth Pockets of dead cells Slowly pushed to surface

PATHOLOGY

MICROCYSTS ONSET AND RECOVERY

35

30

20

10

0

Microcysts (number)

0 2 4 6 8 10 12 0 2 4 6 Time (months)

HWC n=51 CCLRU

HWC n=29 GOTEBORG

MICROCYSTS

. . . Break through the anterior

corneal surface and manifest as

corneal dry spots

(Zantos, 1981)

ENDOTHELIUM

Detection with slit-lamp:

High magnification (30x - 40x)

High illumination

Specular reflection

POLYMEGETHISM SIGNS

Increasing variation in endothelial cell size

Increased ratio of large/small cells

CCLRU POLYMEGETHISM SCALE GRADE

1 2 3 4

CLINICAL SIGNIFICANCE OF POLYMEGETHISM

POLYMEGETHISM

Age

Diseases (diabetes, etc)

Trauma

Contact lenses

CAUSES

TEAR EXAMINATION

Quality

Lipid layer

Debris

TEAR EXAMINATION

Quality BUT (fluorescein)

Tear prism height

Movement of debris

Rose Bengal staining

ANTERIOR CHAMBER

Transparency

Cells and flare

Persistent pupillary membrane

IRIS EXAMINATION

Architecture Inflammation Pigmentation Naevi Iridectomy Colobomas

CRYSTALLINE LENS EXAMINATION

Orange Peel Opacities Pigment on capsule Centration Iris attachments

THANK YOU

Table of Contents

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slit-lamp biomicroscopy module 1.4_final

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