Anatomy, physiology and Anatomy, physiology and pathology of the eye and its pathology of the eye and its

clinical relevanceclinical relevanceDr A. TeyDr A. Tey

SpR in OphthalmologySpR in OphthalmologyNinewells Hospital and Medical SchoolNinewells Hospital and Medical School

The Eye and how it worksThe Eye and how it works

The RetinaThe Retina

– The membrane lining the The membrane lining the back of the eye that back of the eye that contains photoreceptor contains photoreceptor cells. These cells. These photoreceptor nerve cells photoreceptor nerve cells react to the presence react to the presence and intensity of light by and intensity of light by sending an impulse to sending an impulse to the brain via the optic the brain via the optic nerve. In the brain, the nerve. In the brain, the multitude of nerve multitude of nerve impulses received from impulses received from the photoreceptor cells in the photoreceptor cells in the retina are assimilated the retina are assimilated into an image. into an image.

Diabetic RetinopathyDiabetic Retinopathy

• Diabetic retinopathy is a complication of Diabetic retinopathy is a complication of diabetes which is an endocrinological diabetes which is an endocrinological disorder which affects multiple organsdisorder which affects multiple organs

• Diabetic retinopathy is one of the Diabetic retinopathy is one of the commonest causes of blindness in the UK commonest causes of blindness in the UK in people between the ages of 30-65, and in people between the ages of 30-65, and 12% of people who are registered blind 12% of people who are registered blind and partially sighted each year have and partially sighted each year have diabetic eye disease. At any one time up diabetic eye disease. At any one time up to 10% of people with diabetes will have to 10% of people with diabetes will have retinopathy requiring medical follow up or retinopathy requiring medical follow up or treatment. (Moorfields Eye Hospital)treatment. (Moorfields Eye Hospital)

Pathology:Pathology:A A

microangiopamicroangiopathythy

1.1. LeakageLeakage

2.2. Ischaemia Ischaemia

1.1. LeakageLeakage

2.2. IschaemiaIschaemia

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

glycosylation of protein/basement glycosylation of protein/basement membranemembrane

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

glycosylation of protein/basement glycosylation of protein/basement membranemembrane

loss of pericytesloss of pericytes

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

glycosylation of protein/basement membraneglycosylation of protein/basement membrane

loss of pericytesloss of pericytes

reduced Oreduced O22 transport tissue hypoxia transport tissue hypoxia

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

glycosylation of protein/basement membraneglycosylation of protein/basement membrane

loss of pericytesloss of pericytes

reduced Oreduced O22 transport tissue hypoxia transport tissue hypoxia

MicroaneurysmsMicroaneurysms

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

glycosylation of protein/basement membraneglycosylation of protein/basement membrane

loss of pericytesloss of pericytes

reduced Oreduced O22 transport tissue hypoxia transport tissue hypoxia

vaso-formative factors produced vaso-formative factors produced (TGF-(TGF-ββ & VEGF) & VEGF)

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

glycosylation of protein/basement membraneglycosylation of protein/basement membrane

loss of pericytesloss of pericytes

reduced Oreduced O22 transport tissue hypoxia transport tissue hypoxia

vaso-formative factors produced vaso-formative factors produced (TGF-(TGF-ββ & VEGF) & VEGF)

neo-vascularisationneo-vascularisation

Pathogenesis:Pathogenesis:

chronic hyperglycaemiachronic hyperglycaemia

glycosylation of protein/basement membraneglycosylation of protein/basement membrane

loss of pericytesloss of pericytes

reduced Oreduced O22 transport tissue hypoxia transport tissue hypoxia

vaso-formative factors produced vaso-formative factors produced (TGF-(TGF-ββ & VEGF) & VEGF)

neo-vascularisation neo-vascularisation

haemorrhage / scarring haemorrhage / scarring

1.1. HaemorrhageHaemorrhage

2.2. ScaringScaring

new new vesselsvessels

• new vessels grow on posterior vitreous new vessels grow on posterior vitreous faceface

• grow on disc (grow on disc (NVD)NVD)

• grow in the periphery (grow in the periphery (NVE)NVE)

• grow on iris if ischaemia is severegrow on iris if ischaemia is severe

((NVE)NVE)

((NVD)NVD)

((rubeosis iridisrubeosis iridis))

The natural history of neovascularisation – note lack of laser treatment scars

The natural history of neovascularisation – note lack of laser treatment scars

The natural history of neovascularisation – note lack of laser treatment scars

In summary diabetic patients In summary diabetic patients loose vision from:loose vision from:

1.1. retinal oedema affecting the retinal oedema affecting the foveafovea

2.2. vitreous haemorrhage vitreous haemorrhage

3.3. scaring/ tractional retinal scaring/ tractional retinal detachmentdetachment

Classification 1: retinopathyClassification 1: retinopathy

• No retinopathy No retinopathy

• mildmild

• moderatemoderate

• severesevere

• proliferative retinopathyproliferative retinopathy

non-proliferative retinopathy

Classification 1: retinopathyClassification 1: retinopathy

• No retinopathy No retinopathy

• mildmild

• moderatemoderate

• severesevere

• proliferative retinopathyproliferative retinopathy

non-proliferative retinopathy

laser

observe / re-screen

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathyobservable maculopathy

• referable maculopathyreferable maculopathy

• clinically significant maculopathyclinically significant maculopathy

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathyobservable maculopathy

• referable maculopathyreferable maculopathy

• clinically significant maculopathyclinically significant maculopathy laser

observe / re-screen

Signs of non proliferative retinopathySigns of non proliferative retinopathy

• microaneurysms / dot microaneurysms / dot ++ blot blot haemorrhageshaemorrhages

• hard exudatehard exudate

• cotton wool patchescotton wool patches

• abnormalities of venous calibreabnormalities of venous calibre

• Intra-retinal microvascular abnormailitiesIntra-retinal microvascular abnormailities

(IRMA)(IRMA)

mildmild non proliferative retinopathy non proliferative retinopathy

• microaneurysms +/or very small blots microaneurysms +/or very small blots onlyonly

moderatemoderate non proliferative non proliferative retinopathyretinopathy

• microaneurysmsmicroaneurysms

• dot + blot haemorrhagesdot + blot haemorrhages

• venous calibre changes in only 1 venous calibre changes in only 1 quadrantquadrant

(1/4)(1/4)

severesevere non proliferative retinopathy non proliferative retinopathy

• Microaneurysms plus:Microaneurysms plus:

• > 4 per quadrant of dot + blot > 4 per quadrant of dot + blot haemorrhageshaemorrhages

• > 2 quadrants of venous tortuosity/looping> 2 quadrants of venous tortuosity/looping

• > 1 quadrant of IRMA> 1 quadrant of IRMA

‘‘4,2,1 rule’ 4,2,1 rule’

Proliferative retinopathyProliferative retinopathy

• New vessels disc (NVD)New vessels disc (NVD)

• New vessels elsewhere (NVE)New vessels elsewhere (NVE)

Treated if you see laser scars; untreated if no laserTreated if you see laser scars; untreated if no laser

What is happening here?What is happening here?

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathyobservable maculopathy

• referable maculopathyreferable maculopathy

• clinically significant maculopathyclinically significant maculopathy

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathy –observable maculopathy –– Microaneurysms Microaneurysms – Hard exudates Hard exudates – Small haemorrhages Small haemorrhages

Within arcadesWithin arcades

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathy –observable maculopathy –

• referable maculopathyreferable maculopathy– Microaneurysms Microaneurysms – Hard exudates Hard exudates – Small haemorrhages Small haemorrhages

Abnormalities within 1 disc diameter of fixation Abnormalities within 1 disc diameter of fixation (fovea)(fovea)

1 DD

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathyobservable maculopathy

• referable maculopathyreferable maculopathy

• clinically significant maculopathyclinically significant maculopathy

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathyobservable maculopathy

• referable maculopathyreferable maculopathy

• clinically significant maculopathyclinically significant maculopathy laser

observe / re-screen

Classification 2: Classification 2: maculopathymaculopathy

• No maculopathy No maculopathy

• observable maculopathyobservable maculopathy

• referable maculopathyreferable maculopathy

• clinically significant maculopathy*clinically significant maculopathy*laser

observe / re-screen

*defined by ophthalmologist only – stereo view / oedema

500μ

1500μ

Clinically Significant Macular Oedema - 1

Clinically Significant Macular Oedema - 2

Clinically Significant Macular Oedema - 3

1 DD

““If you don’t know what If you don’t know what you are looking for, you are looking for, you won’t know when you won’t know when you find it”you find it”

Winnie the PoohWinnie the Pooh

Courtesy of University of Michigan, Kellogg Eye Center photo archives

Thank youThank you