3. Pathology of the eye Flashcards
Causes for abnormal red reflex?
- Anything obstruc5ng the path of light from the front to the back of the eye
- Corneal Scar
- Cataract
- Vitreous Haemorrhage
- Retinoblastoma
US of retinoblastoma
Calcified
appears white
Bilateral retinoblastoma presents later than unilateral. True or false
False
What is the knudson 2 hit hypothesis for retinoblastoma?
Familial form
• Those with a family history tended to present EARLIER in childhood and often had BILATERAL multi-focal disease
Sporadic (more common)
• Those without a family history presented LATER and only had a SINGLE eye involved
Tumour Suppressor Gene(TSG) – ANTI-ONCOGENE
Optic nerve is 15% nasal to the ….
Fovea
Optic disc appearance
Margin: Defined
Clour: Orange/yellow
Cup: pale hole at centre
What is the cup of retina?
The optic disc has a center portion called the “cup” which is normally quite small in comparison to the entire optic disc. In people with glaucoma damage, because of increased pressure in the eye and/or loss of blood flow to the optic nerve, these nerve fibers begin to die.
Optic atrophy (e.g. in MS) leads to optic disc appearance of…
Pale
Causes of swollen disc?
• Pseudo swelling
– Small Discs
– Drusen
• Genuine swelling • Raised ICP – SOL – IIH – Hydrocephalus
Causes of swollen disc?
• Pseudo swelling
– Small Discs
– Drusen
• Genuine swelling • Raised ICP – SOL – IIH – Hydrocephalus
What is Re5nopathy of Prematurity (ROP)?
- Blinding neovascular re5nal condition driven by hormones including VEGF
- Its therefore like Age Related Macular Degeneration & Diabetic Retinopathy
What 3 aspected of optic disc must be commented on?
Margin, colour, cup
Muscles of the eye
6 extra-ocular muscles
• 2 horizontal recti (medical and lateral)
• 2 vertical recti (superior and inferior)
• 2 oblique (superior and inferior)
S/S of CN III palsy?
• Oblique diplopia • Eye is ‘down & out’ • Diplopia every where • Pupil dilated and ptosis • Can be associated with an aneurysm – needs urgent brain imaging and angiogram
If headache too, need to exclude aneurysm of posterior communicating artery
S/S of CN IV palsy?
• Oblique diplopia • Head tilt *** towards normal side • Worse away from the side of the palsy if unilateral • Common after head injury • Bilateral - might be congenital
S/S of CN VI palsy?
- Horizontal diplopia
- Worse in far distance
- Worse towards the side of the palsy if unilateral
- Bilateral - concerned that raised intracranial pressure is present
ICP risk if bilateral
AMD?
AGE RELATED MACULAR DEGENERATION (AMD)
AMD: Epidem? Types? Symptoms? Treatment?
Most common cause of blindness >65 years in high- income countries
Two types; dry and wet
Symptoms
• Progressive reduction in visual acuity.
• Metamorphopsia may suggest wet AMD
Treatment; rehabilitation and anti-VEGF injections
Diabetic retinopathy:
Epidem?
Results in?
MoA
- Main cause of blindness in working age in ‘western’ countries
- Growing cause of blindness in low and middle income countries
Result:
• Damage to retinal micro-vasculature
• Blindness due to:
– Growth of new vessels: Leading to vitreous haemorrhage, tractional retinal detachment and rubeotic glaucoma
– Leakage of fluid from damaged vessels: Causes Macular oedema with loss of central visual acuity
MoA
- Glycosylation of vessels
- Hypoxia
- VEGF release
- New vessels are formed
- Neovascularisation and leakage
- Macular oedema, vitreous haemorrhage, retinal detachment and rubeotic glaucoma
Pathophysiology of diabetic eye?
- Chronic hyperglycaemia
- Glycosylation of protein/basement membrane 3. Loss of pericytes
- Reduced O2 transport = tissue hypoxia
- Vaso-proliferative factors produced (VEGF)
- Neo-vascularisation and leakage
- Macular oedema, vitreous haemorrhage, retinal detachment and rubeotic glaucoma
Classification of diabetic retinopathy?
- No retinopathy
- Non-proliferative retinopathy
– Mild
– Moderate
– Severe - Proliferative retinopathy
Signs of non-proliferative diabetic retinopathy?
- Microaneurysms
- Dot & blot haemorrhages
- Hard exudates
- Cotton wool spots
- Abnormalities of venous calibre
- Intra-retinal microvascular abnormalities (IRMA)
For the following diabetic retinopathy, what is the approach? 1. No retinopathy 2. Non-proliferative retinopathy – Mild – Moderate – Severe 3. Proliferative retinopathy
(Screen ) 1. No retinopathy 2. Non-proliferative retinopathy – Mild (Refer to ophthalmology) – Moderate – Severe (Treat) 3. Proliferative retinopathy
Classifications of maculopathy?
- No maculopathy
- Observable maculopathy
- Referable maculopathy
- Clinically significant maculopathy
For the following diabetic maculopathy, what is the approach? • No maculopathy • Observable maculopathy • Referable maculopathy • Clinically significant maculopathy
Continue to screen- • No maculopathy • Observable maculopathy Refer to ophthalmology- • Referable maculopathy Treat- • Clinically significant maculopathy
Maculopathy treatment:
- Lifestyle-stop smoking, weight control, exercise
- Glycaemic control
- Blood pressure control
- Dyslipidaemia control
- Support renal function-ACE inhibitors
- Laser, anti-VEGF injections and surgery
VEGF?
Vascular endothelial growth factor
Different classifications of clinically significant macular oedema?
1- Retinal oedema within 500um of the centre of the macula
2- Hard exudates within 500um of the centre of the macula, if associates with retinal thickeninngs
3- Retinal oedema one disc area (1500um) or larger, any part of which is within one disc diameter of the centre of the macula
Hard exudate hints at…
oedema
