Transcript Cup Edge - Moorfields Eye Hospital

Diabetic retinopathy screening
NSF-based training
Anatomy and physiology
Tunde Peto
Head of Reading Centre
Anatomy and physiology of
the normal human eye
Key issues for discussion
• Review the gross anatomical structures within and related
to the eyeball and discuss their basic function
• Review the basic physiology of refraction and vision
Learning outcome
• Identify the different structures of the eye and discuss their
basic function
• Identify different anatomical structures on teaching slides
Basic Science in relation to eye
disease: the normal retina and
vision
Key issues for discussion
• The normal anatomy of the retina
• Photoreceptors and their biochemistry
• Physiology of vision including colour vision
Learning outcome
• Identify normal retinal structure on teaching
slides
Vision
• Reflected light translated into mental image
• Pupil limits light, lens focuses light
• Retinal rods and cones are photoreceptors
Figure 10-36: Photoreceptors in the fovea
Photoreceptors
• Rods – monochromatic, provide night vision:
most numerous in periphery, sees all shades of
grey and white; see in dark and around us
• Peripheral changes might not affect the vision at
all
• Laser treatment and retinal detachment might
result in visual field loss
• Cones – red, green, & blue; color & details, most
numerous in macula; you need very few for good
vision!
Photoreception and Local Integration
Figure 10-35: ANATOMY SUMMARY: The Retina
Retina: More Detail
Figure 10-38: Photoreceptors: rods and cones
Vision: Integration of Signals to Perception
• Bipolar
• Ganglion
– Movement
– Color
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Optic nerve
Optic chiasm
Optic tract
Thalamus
Visual cortex
Figure 10-29b, c: Neural pathways for vision and the papillary reflex
The aging retina: Age Related Maculopathy
(ARM) and Macula Degeneration (AMD)
Key issues for discussion
• Normal changes in the aging retina
• Abnormal changes in the aging retina
• The constituents of drusen
• Geographic atrophy
• Neovascular AMD
Learning outcome
• Identify age related changes in the retina
• Identify and discuss different types of drusen
• Identify geographic atrophy
• Identify and discuss the main features of neovascular AMD
Hard drusen (<63 mikron)
Normal SLO
image
Hard and intermediate soft
drusen (63-125 mikron)
Large soft Drusen on the posterior pole
Watch it developing over the years
2 years later
5 years later
7 years later
10 years later: some areas atrophied
Geographic Atrophy
Neovascular membrane at the fovea
Neovascular membrane at the fovea
FFA of the neovascular membranes: R eye: occult,
L eye classic membrane
Right eye: occult membrane
Left eye: classic membrane
Fibrovascular scar and secondary atrophy
Neovascular membrane on SLO imaging
Pigment epithelial detachment: colour image
Pigment epithelial detachment on FFA
Pigment epithelial detachment: SLO image
Vascular occlusion
Key issues for discussion
• Learn normal vasculature of the eye
• Discuss most common systemic causes of vascular problems in
the eye
• Discuss vein occlusion
• Discuss arterial occlusion
• Discuss clinical implications of these diseases
Learning outcome
• Identify normal and abnormal vascular structures in the eye on
teaching slides
• Identify strategies to deal with these diseases
Central retinal
vein occlusion:
Introduction
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dilated, tortuous veins & haems in all 4 quadrants
ischaemic (iCRVO) vs. non ischaemic (niCRVO)
ischaemic = non perfused, haemorrhagic
non-ischaemic = perfused, venous stasis retinopathy
Epidemiology (EDCCS)
• 2 per 1000 > 40 years, 5.5 per 1000 > 64
years
• 33% ischaemic, 67% non ischaemic
• 13% < 45 years, 11% 45-54 years, 76% > 55
years
Clinical features
• reduced visual acuity
• RAPD
• retinal predictors of ischaemia
– degree of intraretinal haemorrhage
– venous dilatation
– venous tortuosity
• as chronicity develops
– IRMA, microaneurysms, collateral vessels
Complications
• macular oedema, ischaemia
• NVE / NVD (6-7%)
• iris neovascularisation (NVI), neovascular
glaucoma (NVG) (21%)
• cilioretinal artery occlusion
• combined with CRAO
Large areas of ischaemia
on FFA
Iris neovascularisation
Comined with CRAO: cherry
red spot with white macula
Classification
• ischaemic vs non-ischaemic
– two ends of a spectrum
– elderly: if severe, retinal capillaries decompensate, iCRVO
– young: if mild or moderate, retinal capillaries withstand
increased venous pressure, niCRVO
• young vs old
–  40 yrs, 64% final VA  6/9
– > 40 yrs, 40% iCRVO
Good perfusion on FFA
Poor peripheral perfusion on
FFA
Differential diagnosis
• Anterior ischaemic optic neuropathy / optic
neuritis / optic nerve invasion
• asymmetrical diabetic retinopathy
• ocular ischaemic syndrome
• severe anaemia, leukaemia
• Waldenstroms macroglobulinaemia
• carotico-cavernous fistula
Branch retinal vein occlusion
• A cause should be found for it!
• Most common caused: diabetes mellitus,
hypertension and lipid abnormalities
• Investigations need to be done by the referring
physician, not in screening setting, however, you
need to notify the physician
• You will find asymptomatic old BRVO-s in
screening setting
Embolic disease: local protocol, but requires GP
notification so risk factors for stroke and sight
threatening disease can be addressed
The normal optic nerve and its
pathological changes
Key issues for discussion
• Learn the normal anatomy of the optic nerve
• Discuss the function of the optic nerve and its connection
to the brain
• Discuss major illnesses affecting the optic nerve
• Discuss the main features of the glaucomatous changes of
the optic nerve
Learning outcome
• Identify the main features of the optic nerve and discuss
the function
• Identify normal optic nerve on teaching slides
• Identify the main features of the diseases optic nerve
The Normal Optic Nerve Head
•
The optic nerve head can be imagined as a ‘plug-hole’ down
which over 1 million nerve fibres descend through a sieve-like
sheet known as the lamina cribrosa. These fibres are then
bundled together behind the eye as the optic nerve which
continues towards the brain.
• The retinal nerve fibres are spread unevenly across the surface of
the retina in a thin layer. As the nerve fibres converge on the edge
of the disc they pour over the scleral ring and then down its inner
surface. This dense packing of nerve fibres just inside the scleral
ring is visualized as the neuroretinal rim.
• The inner (with respect to the centre of the optic nerve head) edge
of this neuroretinal rim marks the most central of the nerve fibres.
This edge is usually sloped, yet may be range from an overhang to
vertical to a gentle slope towards the centre of the disc. This inner
edge marks the cup edge.
Scleral
Ring
Outer edge
Inner edge (outer edge of
disc or neuroretinal rim
Neuro-retinal
rim
Cup
Edge
Change in direction
of blood vessel
The Scleral Ring
• This ring is usually pale allowing it to be
distinguished from the neuroretinal rim
tissue which is pink. The ring may not be
visible in a given disc image, or the
visibility may vary in different areas of the
circumference of the disc. It is often easier
to see on the temporal side of the disc than
on the nasal side.
Scleral ring
As vessels bridge the scleral ring, they often make
a slight change in direction (black arrow) which
may be a clue to its inner edge,
Inner
The change in colour is also evident in this case
(arrows mark inner and outer edges)
Blurring of the image may occur due to media
opacity or resolution of the image- this can make
appreciation of the anatomy difficult.
Outer
The Cup edge
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This is undoubtedly the most difficult contour to identify, and is subject to more variability than the
disc edge.
The inner edge of the neuroretinal rim (=cup edge) may be sloped (especially on the temporal side
of the disc) or vertical. In some cases the edge may be an overhang.
The most effective way of drawing this ring is to identify certain points on the cup edge where you
are sure of its location, and then using a dot-to-dot procedure link up these points into a ring. First
look for a blood vessel, preferably a small to medium-sized one (large vessels do not hug the
surface and may not be tethered to the surface and therefore are unhelpful). Trace its path across the
scleral ring and then over the rim tissue- at some point it will change direction as it bends inward
towards the centre of the disc. If the slope is shallow this will be a gradual change in direction,
however if vertical it will be an obvious bend, and in the case of an overhang it will suddenly
disappear from view. It is the point of maximum change of direction of the vessel that marks the
cup edge. When viewing the disc in stereo, the edge of the cup can often be clearly seen in areas
where there are no vessels as a guide.
There can be a temptation to mark the cup edge where the colour changes from the pink of the rim
to the pallor of the cup. In many situations this would be correct, yet in some situations the edge of
pallor is not necessarily the edge of the cup, and hence it is better to rely on vessels and stereo cues
as described above.
The following images illustrate these points.
The cup edge
The Cup Edge:
3 blood vessels here show the edge
of the cup:
The points of maximum inflection
(bend) are marked by arrows.
The cup edge
Cup Edge:
In this very clear image, the
arrows mark the cup edge. This
illustrates that occasionally large
vessels may obscure the edge
from view, and in this case one
should mark points of certainty
either side of the vessel and link
these up.
Optic nerve head assessment
Dr. Patricio Schlottmann
Research Fellow
Glaucoma Research Unit
Overview
• Glaucoma definition
• Anatomy
• Risk factors
• Cup/disc
Definition
• Glaucoma is a chronic, progressive optic
neuropathy that manifests by a
characteristic Visual Field loss and
distinctive structural changes recognizable
at the level of the Optic nerve head or the
Retinal Nerve Fibre Layer (RNFL)
Definition
• Chronic: having a progressive course of
indefinite duration
• Progressive: tending to become more severe
• Optic neuropathy: disease of the of the optic
nerve
Definition
• Optic neuropathy
– The ganglion cells and their axons are the
damaged structures
– Other cells within the retina are also affected
Anatomy
Anatomy
Risk Factors
• Major risk factors for developing glaucoma
are:
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1. elevated intraocular pressure
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2. African descent
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3. family history of glaucoma
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4. increased age
Risk factors
• Elevated intraocular pressure
Risk factors
• African derived individuals
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Glaucoma is 4 times more prevalent
Is usually more severe
Starts at earlier age
Progresses more rapidly
Risk Factors
• Family history of glaucoma
– A first degree relative affected by glaucoma
increases the risk of developing the disease in
the future
– Patients should be questioned about the severity
of glaucoma in the affected relative
Risk Factors
• Increased age
– Prevalence increases with age
– It is 10% of subjects over 80 years
Cup/disc
• Definition
– Relationship between cup area and disc area
Disc
Cup
Cup/disc
• Examples
0.1
0.7
0.3
0.5
0.8
0.95
What to look for?
• Large cup/disc
– >0.7-0.8
• Asymmetry
– >0.2-0.3 between eyes
• Haemorrhages
What to look for?
• Notches
– Focal loss of fibres
• Areas of thinning
– Diffuse thinning of the rim
Screening for glaucoma
• Too many false positives
– 2% subjects over 40
– Advanced condition is easier to diagnose
What to do with a suspect?
• They will need referral to eye department
– Phenotyping
– Decision on treatment or observation
Phenotyping
• Complete evaluation of the patient
– Medical history
– Risk factors
– Medications
– Scans
– VF
– Clinical examination w/dilation
3 hours visit
Examples
Examples
Examples
Examples