09-10-23 - Pathology of the eye Flashcards
Learning outcomes
- Understand some of the causes of worldwide blindness
- Understand why there are differences between high, middle and low-income countries and between adults and children
- Appreciate the normal red reflex and fundal appearance
- Appreciate what an abnormal red reflex and fundus look like and possible causes
- Describe signs of diabetic retinopathy, retinopathy of prematurity, pathological optic nerves, cataract, age related macular degeneration
- Understand the basics of extra-ocular eye movements
- Appreciate some of the imaging tools in ophthalmology
What are the 6 leading causes of blindness/SSI (severe sight impairment)?
What % of cases are avoidable or treatable?
- 6 leading causes of blindness/SSI (severe sight impairment):
1) Cataract (leading cause worldwide)
2) Uncorrected refractive error
3) Age-related macular degeneration (leading cause in the UK)
4) Diabetic retinopathy
5) Glaucoma
6) Corneal opacities - 80% of cases are avoidable or treatable
Eye diagram (in picture)
Describe the WHO WHO categories of visual impairment (note these are not the definitions for being registered as sightimpaired in the UK) (in picture)
What are cataracts?
What are 7 risk factors for cataracts?
- Cataracts is a cloudy area in the lens of the eye
- 7 risk factors for cataracts:
1) Age - very common as we get older
2) Diabetes
3) Trauma
4) Inflammation
5) Steroid use
6) UV/Radiation
7) Congenital
What are corneal ulcers?
What is it often caused by?
What are 5 risk factors for corneal ulcers?
How do we treat this?
What can be left behind?
What is a hypopyon?
- A corneal ulcer (aka keratitis) is an open sore in the outer layer of the cornea.
- It is often caused by infection
- 5 Risk factors for corneal ulcers:
1) CONTACT LENSES*
2) Varicella/Herpes (viruses)
3) Steroid drop use
4) Dry eyes/Exposure
5) Trauma/Burns - This can be treated through corneal transplant
- This can leave scarring
- A hypopyon is the accumulation of white blood cells that form a whitish layer of fluid in the lower portion of the eye’s anterior chamber (front part).
- They can be seen in corneal ulcers
What leads to an abnormal retinal reflex?
What 4 conditions can cause a red retinal reflex?
- An an abnormal retinal reflex is caused due to something obstructing the path of light from the front to the back of the eye
- 4 conditions can cause a red retinal reflex:
1) Corneal ulcer
2) Retinoblastoma (especially in small children)
3) Cataracts
4) Vitreous haemorrhage (vitreous cavity of the eye)
What is the fundus?
What is it made up of?
How is it photographed?
What are the 2 forms of ophthalmoscopy?
Describe the appearance of a normal fundus (in picture)
- The fundus is the inside, back surface of the eye.
- It is made up of the retina, macula, optic disc, fovea and blood vessels.
- With fundus photography (fundoscopy/ophthalmoscopy), a special fundus camera points through the pupil to the back of the eye and takes pictures
- Ophthalmoscopy can be broken up into two types, direct and indirect.
- Direct ophthalmoscopy provides an upright, unreversed image of around 15 times magnification, while indirect ophthalmoscopy produces a reversed, inverted image magnified 2 to 5 times (in picture)
- Appearance of a normal fundus (in picture)
What is an OCT scan?
What is it used for?
Describe the Normal OCT scan of the fovea (in picture)
- Optical coherence tomography (OCT) is a noninvasive imaging method that uses reflected light to create pictures of the back of your eye
- Normal OCT scan of the fovea (in picture)
What is a retinoblastoma?
What was it the first condition to be described by?
What gene is involved?
Which forms are hereditary and non-hereditary?
Why does every newborn get a retinal reflex check?
- A retinoblastoma is malignant tumour of the retina
- It was the first condition to be described by Knudson’s ‘2-hit’ hypothesis
- Retinoblastomas involve the RB1 - tumour suppressor gene
- Hereditary retinoblastoma - earlier, bilateral
- Non-hereditary retinoblastoma - later, unilateral
- Every newborn gets a retinal reflex check to pick up retinoblastoma and cataracts early
What is diabetic retinopathy?
What are 2 reasons for reduced vision in diabetic retinopathy?
What are 4 parts of the treatment for DR?
- Diabetic retinopathy is an eye condition that can cause vision loss and blindness in people who have diabetes
- 2 reasons for reduced vision in diabetic retinopathy (DR):
1) Growth of new vessels (proliferative DR)
* Can lead to vitreous haemorrhage, tractional retinal detachment and rubeotic glaucoma
* Glaucoma associated with rubeosis of the iris is one of the most lethal forms of the disease
* Neovascularization of the iris (NVI), also known as rubeosis iridis, is when, blood vessels develop on the anterior surface of the iris in response to retinal ischemia
2) Leakage of fluid from damaged vessels
* Can lead to macular oedema with loss of central visual acuity
* 4 parts of the treatment for DR:
1) Lifestyle – smoking, weight, exercise
2) Blood sugar/pressure/cholesterol
3) support renal function
4) Laser and anti-VEGF (Vascular endothelial growth factor) surgery
Proliferative diabetic retinopathy
‘New vessels elsewhere’ (NVE) – Proliferative DR
New vessels at the disc (NVE) – Proliferative DR
Haemorrhage from new vessels in Proliferative DR
Fibrosis with tractional retinal detachment in severe proliferative DR
‘Rubeosis iridis’ due to proliferative DR (this can also occur following a CRVO)
Diabetic maculopathy with exudates
Laser treatment for proliferative DR (also evidence of maculopathy)
Describe the pathogenesis of diabetic retinopathy (in picture)
When does diabetic retinopathy of prematurity (ROP)?
How is it prevented in the UK?
What will it cause if left untreated?
How is it treated?
How does it present?
- Diabetic retinopathy of prematurity (ROP) occurs when babies are born before their retina is vascularised
- There is a screening programme in the UK
- Will cause severe sight impairment if left untreated
- Has a similar mechanism and treatment to DR
- ROP presents with vessel tortuosity and a demarcation line seen where the avascular retina meets vascularized retina
What is Age-related macular degeneration (AMD) the most common cause of?
What are the 2 types of AMD?
What are 2 symptoms of AMD?
How do the treatments between dry and wet AMD differ?
Describe the presentation of Wet AMD and ophthalmoscopy and OCT scan (in picture)
- Age-related macular degeneration (AMD) is the Most common cause of SSI > 65 years in high-income countries
- The 2 types of AMD are dry and wet
- 2 symptoms of AMD:
1) Progressive reduction in visual acuity.
2) Metamorphopsia (shape of objects appear distorted) may suggest wet AMD - For Wet AMD, we use prevention, rehabilitation, and anti-VEGF infections (Vascular endothelial growth factor)
- There is no direct treatment for dry AMD, with the most common treatment being vitamin supplements to prevent the condition from getting worse
- The presentation of Wet AMD and ophthalmoscopy and OCT scan (in picture)
What is the optic disc?
What is its role?
What are the 5 optic discs we are expected to know?
- The optic disc is the round spot on the retina
- It is formed by the passage of the axons of the retinal ganglion cells, which transfer signals from the photoreceptors of the eye to the optic nerve, allowing us to see.
- 5 optic discs we are expected to know:
1) Normal
2) Swollen
3) New vessels
4) Cupped
5) Pale
Swollen optic discs.
What is a cause of pseudo swelling of the optic discs?
What are 4 signs of swollen optic discs?
What are 4 causes of genuine swelling of the optic discs?
What are 7 symptoms of raised ICP?
- Swollen optic disks
- Pseudo-swelling of optic discs is caused by drusen, which are small calcifications
- 4 signs of swollen optic discs:
1) Outline of disc is less distinc
2) Little haemorrhages on the edge of disc
3) Obscuration of blood vessels as they pass over the edge
4) Disc looks red and swollen - 4 causes of genuine swelling of the optic discs:
1) Raised ICP
2) SOL (space occupying lesion e.g brain tumour)
3) IIH (idiopathic intracranial hypertension)
4) Hydrocephalus (blockage of CSN drainage system, which backs up and causes raised ICP) - 7 Symptoms of raised ICP:
1) Headaches, especially when bending forwards (frontal)
2) Vomiting/nausea
3) Visual disturbance
4) Tinnitus (hearing noises that do not come from an outside source)
5) Confusion
6) Pupillary abnormalities
7) Diplopia (double vision)
When are new vessels seen on the optic disc?
- New vessels can be seen on optic discs in proliferative diabetic retinopathy
Describe the appearance of a cupped optic disc.
What is a cupped disc a sign of?
- In cupped optics discs, there us a centre pale area and a larger outer area
- The gap between the cup (centre circle) and the disc (outer circle) is thinner in a cupped disc, which is a sign of glaucoma
What are 4 potential causes of a pale optic disc?
- 4 potential causes of a pale optic disc?
1) Long term compression of the optic nerve by potentially a slow growing tumour such as a meningioma
2) Previous ischaemic problem
3) A nutritional deficiency, such as B12, or folate
4) Atrophy of retinal nerve fibres in the optic disc
What is glaucoma?
What is a characteristic defect of it?
When do patients become aware of this?
What is it most commonly caused by?
What are 2 treatments of glaucoma?
- Glaucoma is a common eye condition where the optic nerve, which connects the eye to the brain, becomes damaged.
- It has a characteristic visual field defect
- Patients are often unaware of this deficit until advanced disease
- It is most commonly caused by raised IOP (intraocular pressure) due to fluid build up in the anterior chamber of the eye
- 2 treatments of glaucoma:
1) Drops (inflow reductio, outflow increase)
2) Surgery (outflow increase)
Describe the visual pathway to the primary visual cortices (in picture).
What can tumours pressing on the optic chiasm cause?
What is bitemporal hemianopsia?
How can lesions on one side affect the other side?
- The visual pathway to the primary visual cortices (in picture).
- Tumour pressing on the optic chiasm can cause bilateral visual field defects e.g bitemporal hemianopia
- Bitemporal hemianopsia (or bitemporal hemianopia) describes the ocular defect that leads to impaired peripheral vision in the outer temporal halves of the visual field of each eye
- Lesions on one side can affect both eyes, causing visual field defects
- This is due to the decussation (crossing over) of fibres at the optic chiasm
Where does the trochlear nerve (CN4) decussate?
Which side supplies the superior oblique muscle of the eye?
- The trochlear (CN4) nerve decussates within the brainstem, hence the superior oblique is supplied by the contralateral trochlear nucleus
- This means the left trochlear nerve is supplied by the right trochlear nucleus
What 6 extraocular muscles control eye movements?
What is a palsy?
Palsies of what 3 cranial nerves will lead to diplopia (double vision)?
Which is the most common?
- 6 extraocular muscles control eye movements:
1) 2 vertical recti (superior and inferior) – innervated by CN3
2) 2 oblique (superior and inferior) – innervated by CN3 and CN4 respectively
3) 2 horizontal recti (medial and lateral) innervated by CN3 and CN6 respectively
- A palsy is paralysis, especially that which is accompanied by involuntary tremors.
- Palsies of 3 cranial nerves that will lead to diplopia (double vision):
1) 3rd cranial nerve palsy (occulomotor nerve) – Vertical diplopia
2) 4TH cranial nerve palsy (trochlear nerve) – Oblique diplopia
3) 6th cranial nerve palsy (abducens nerve) – horizontal diplopia
- The most common is 6th CNP caused by vasculopathy
What are 3 causes of 3CNP (cranial nerve palsy)?
What are 5 signs/symptoms of 3CNP?
- 3 causes of 3CNP (cranial nerve palsy):
1) Vasculopathy
2) Tumour
3) Aneurysm (needs urgent neuroimaging) - 5 Signs/symptoms of 3CNP:
1) Vertical diplopia
* Eye is ‘down & out’ - CN6 pulls it out, CN4 pulls it down
2) Diplopia (double visison) everywhere they look
3) Pupil dilated
* CN3 transmits some pupillary fibres
4) Ptosis
* Ptosis (eye-lid drooping) because CN3 innervates the levator palpebrae superioris muscle that lifts the eye lid
5) Can be associated with an aneurysm
* Posterior communicating artery)
* Needs urgent brain imaging and angiogram
What are 3 causes of 4CNP?
What are 4 signs/symptoms of 4NCP?
- 3 causes of 4CNP:
1) Vasculopathic
2) Tumour
3) Congenital Trauma - 4 Signs/symptoms of 4NCP?
1) Oblique diplopia
* Head tilt away from side of the lesion
* CN4 supplies the superior oblique, so this has a tortional affect on the eye
* Right 4th nerve palsy affects the right eye
2) Diplopia worse away from the side of the palsy if unilateral (adduction);
3) Common after head injury
4) Bilateral - might be congenital.
What are 3 causes of 6CNP?
Which is the most common CNP?
What are 5 signs/symptoms of 6 CNP?
What are we concerned with bilateral diplopia?
What is the 6th CN more vulnerable to?
- 3 causes of 6CNP:
1) Vasculopathic
2) Tumour
3) Cranial pressure? - 6CNP caused by vasculopathy is the most common CNP
- 5 Signs/symptoms of 6 CNP:
1) Horizontal diplopia
* Image split side by side
2) Worse diplopia in far distance
* When looking into the distance, the eyes diverge, as this is when the lateral rectus comes into play (one of the horizontal recti controlled by CN6)
3) Worse diplopia towards the side of the palsy if unilateral
4) Bilateral - concerned that raised intracranial pressure is present
5) Unable to abduct eye on affected side
- The 6th CN is more vulnerable to raised ICP
CNP summaries
CNP summaries
Diplopia summaries
