Ophthalmology Flashcards
What is Glaucoma and is it caused by?
Glaucoma refers to the optic nerve damage that is caused by a significant rise in intraocular pressure. The raised intraocular pressure is caused by a** blockage in aqueous humour** trying to escape the eye.
There are two types of glaucoma: WHat are they?
There are two types of glaucoma: open-angle and closed-angle.
The vitreous chamber of the eye is filled with _______ _______
The vitreous chamber of the eye is filled with vitreous humour.
The anterior chamber between the ________ and the ____ and the posterior chamber between the ____ and the ____ are filled with aqueous humour that supplies nutrients to the cornea.
The anterior chamber between the cornea and the iris and the posterior chamber between the lens and the iris are filled with aqueous humour that supplies nutrients to the cornea.
The aqueous humour is produced by the
The aqueous humour is produced by the ciliary body.
The aqueous humour flows from the ciliary body, around the lens and under the iris, through the anterior chamber, through the ________ ____ and into the ___ __ _____. From the ____ ____ ____ it eventually enters the general circulation.
The aqueous humour flows from the ciliary body, around the lens and under the iris, through the anterior chamber, through the trabecular meshwork and into the canal of Schlemm. From the** canal of Schlemm** it eventually enters the general circulation.
The normal intraocular pressure is ___ ___ mmHg.
he normal intraocular pressure is 10-21 mmHg.
How is normal intraocular pressure created
This pressure is created by the resistance to flow through the trabecular meshwork into the canal of Schlemm.
What is the patho of open angle glucoma
In open-angle glaucoma, there is a **gradual increase in resistance through the trabecular meshwork. **This makes it more difficult for aqueous humour to flow through the meshwork and exit the eye. Therefore the pressure slowly builds within the eye and this gives a slow and chronic onset of glaucoma.
= increase in resistance in the trabecular meshwork
= increased intracocular pressure
What is the patho of acute angle-closure glaucoma
In acute angle-closure glaucoma, the** iris bulges forward** and seals off the trabecular meshwork from the anterior chamber preventing aqueous humour from being able to drain away. This leads to a continual build-up of pressure. The pressure builds up particularly in the posterior chamber, which causes pressure behind the iris and worsens the closure of the angle.
TRUE OR FALSE
acute angle-closure glaucoma is an opthalmology emergency
TRUE
What is cupping
Increased pressure in the eye causes cupping of the optic disc. In the centre of a normal optic disc is the optic cup. This is a small indent in the optic disc. It is usually less than half the size of the optic disc. When there is raised intraocular pressure, this indent becomes larger as the pressure in the eye puts pressure on that indent making it wider and deeper. This is called “cupping”
What is an abnormal size for optic cup?
An optic cup greater than 0.5 the size of the optic disc is abnormal.
RF for GLucoma
- Increasing age
- Family history
- Black ethnic origin
- Nearsightedness (myopia)
Presentation of Open-Angle Glaucoma
Often the rise in intraocular pressure is** asymptomatic** for a long period of time. It is diagnosed by routine screening when attending optometry for an eye check.
It can present with gradual onset of fluctuating pain, headaches, blurred vision and halos appearing around lights, particularly at night time.
Glaucoma affects ________ vision first. Gradually the ________ vision closes in until they experience ____ vision.
Glaucoma affects peripheral vision first. Gradually the peripheral vision closes in until they experience tunnel vision.
How can you measure intracular Pressure
Non-contact tonometry
Goldmann applanation tonometry
What is Non-contact tonometry
Non-contact tonometry is the commonly used machine for estimating intraocular pressure by opticians. It involves shooting a “puff of air” at the cornea and measuring the corneal response to that air. It is less accurate but gives a helpful estimate for general screening purposes.
What is Goldmann applanation tonometry
Goldmann applanation tonometry is the gold standard way to measure intraocular pressure. This involves a special device mounted on a slip lamp that makes contact with the cornea and applies different pressures to the front of the cornea to get an accurate measurement of what the intraocular pressure is.
Diagnosis of open angle glaucoma
Goldmann applanation tonometry can be used to check the intraocular pressure.
Fundoscopy assessment to check for optic disc cupping and optic nerve health.
**Visual field assessment **to check for peripheral vision loss.
Management of Open-Angle Glaucoma
Management of glaucoma aims to reduce the intraocular pressure. Treatment is usually started at an intraocular pressure of 24 mmHg or above. Patients are followed up closely to assess the response to treatment.
**Prostaglandin analogue eye drops **(e.g. latanoprost) are first line. These increase uveoscleral outflow. Notable side effects are eyelash growth, eyelid pigmentation and iris pigmentation (browning).
Other options:
Beta-blockers (e.g. timolol) reduce the production of aqueous humour
Carbonic anhydrase inhibitors (e.g. dorzolamide) reduce the production of aqueous humour
**Sympathomimetics **(e.g. brimonidine) reduce the production of aqueous fluid and increase uveoscleral outflow
What is Trabeculectomy
Trabeculectomy surgery may be required where eye drops are ineffective. This involves creating a new channel from the anterior chamber, through the sclera to a location under the conjunctiva. It causes a **“bleb” **under the conjunctiva where the aqueous humour drains. It is then reabsorbed from this bleb into the general circulation.
Acute angle-closure glaucoma is an ophthalmology emergency. What happens if treatment is not given immediatley
Premanent vision loss
Acute angle-closure glaucoma Risk Factors
The risk factors are slightly different to open-angle glaucoma:
- Increasing age
- Females are affected around 4 times more often than males
- Family history
- Chinese and East Asian ethnic origin. Unlike open-angle glaucoma, it is rare in people of black ethnic origin.
- Shallow anterior chamber
- Medication
Certain medications can precipitate acute angle-closure glaucoma like:
- **Adrenergic **medications such as noradrenalin
- Anticholinergic medications such as oxybutynin and solifenacin
- Tricyclic antidepressants such as amitriptyline, which have anticholinergic effects
Presentation of Acute angle-closure glaucoma
The patient will generally appear unwell in themselves. They have a short history of:
- Severely painful red eye
- Blurred vision
- Halos around lights
- Associated headache, nausea and vomiting
Examination Findings of Acute angle-closure glaucoma
- Red-eye
- Teary
- Hazy cornea
- Decreased visual acuity
- Dilatation of the affected pupil
- Fixed pupil size
- Firm eyeball on palpation
Initial Management of Acute angle-closure glaucoma
NICE CKS 2019 say patients with potentially life-threatening causes of red eye should be referred for same-day assessment by an ophthalmologist. If there is a delay in admission, whilst waiting for an ambulance:
- Lie patient on their back without a pillow
- Give pilocarpine eye drops (2% for blue, 4% for brown eyes)
- Give acetazolamide 500 mg orally
- Given analgesia and an antiemetic if required
Pilocarpine acts on the **muscarinic receptors **in the sphincter muscles in the iris and causes constriction of the pupil. Therefore it is a miotic agent. It also causes ciliary muscle contraction. These two effects cause the pathway for the flow of aqueous humour from the ciliary body, around the iris and into the trabecular meshwork to open up.
Acetazolamide is a carbonic anhydrase inhibitor. This reduces the production of aqueous humour.
Secondary Care Management for Acute angle-closure glaucoma
Various medical options can be tried to reduce the pressure:
- Pilocarpine
- Acetazolamide (oral or IV)
- Hyperosmotic agents such as glycerol or mannitol increase the osmotic gradient between the blood and the fluid in the eye
- Timolol is a beta-blocker that reduces the production of aqueous humour
- **Dorzolamide **is a carbonic anhydrase inhibitor that reduces the production of aqueous humour
- **Brimonidine **is a sympathomimetic that reduces the production of aqueous fluid and increase uveoscleral outflow
What is Laser iridotomy
Laser iridotomy is usually required as a definitive treatment. This involves using a laser to make a hole in the iris to allow the aqueous humour to flow from the posterior chamber into the anterior chamber. The relieves pressure that was pushing the iris against the cornea and allows the humour the drain
What is Age-related macular degeneration (AMD)
Age-related macular degeneration is a condition where there is degeneration in the macula that cause a progressive deterioration in vision.
In the UK it is the most common cause of blindness is
Age Related Macular Degeneration
A key finding associated with macular degeneration is ____ seen during fundoscopy.
A key finding associated with macular degeneration is drusen seen during fundoscopy.
There are two types, ____ and ____. 90% of cases are ____ and 10% are ____. ____ age-related macular degeneration carries a worse prognosis.
There are two types, wet and** dry**. 90% of cases are **dry **and 10% are wet. **Wet **age-related macular degeneration carries a worse prognosis.
The macula is made of four key layers. At the bottom, there is the _____ _____, which contains blood vessels that provide the blood supply to the macula. Above that is ________ membrane. Above ________ membrane there is the ________ ________ epithelium and above that are the __________.
The macula is made of four key layers. At the bottom, there is the choroid layer, which contains blood vessels that provide the blood supply to the macula. Above that is Bruch’s membrane. Above Bruch’s membrane there is the** retinal pigment epithelium **and above that are the photoreceptors.
What are drusen
Drusen are yellow deposits of proteins and lipids that appear between the retinal pigment epithelium and Bruch’s membrane. Some drusen can be normal. Normal drusen are small (< 63 micrometres) and hard. Larger and greater numbers of drusen can be an early sign of macular degeneration. They are common to both wet and dry AMD.
Other features that are common to wet and dry AMD are:
- Atrophy of the retinal pigment epithelium
- Degeneration of the photoreceptors
What is vascular endothelial growth factor (VEGF)
In wet AMD there is the development of new vessels growing from the choroid layer into the retina. These vessels can leak fluid or blood and cause oedema and more rapid loss of vision. A key chemical that stimulates the development of new vessels is vascular endothelial growth factor (VEGF) and this is the target of medications to treat wet AMD.
Risk Factors of AMD
- Age
- Smoking
- White or Chinese ethnic origin
- Family history
- Cardiovascular disease
Presentation of AMD
There are some key visual changes to remember for spotting AMD in your exams:
- Gradual worsening central visual field loss
- Reduced visual acuity
- Crooked or wavy appearance to straight lines
Wet age-related macular degeneration presents more acutely. It can present with a loss of vision over days and progress to full loss of vision over 2-3 years. It often progresses to bilateral disease.
Examination of AMD
- Reduced acuity using a Snellen chart
- Scotoma (a central patch of vision loss)
- Amsler grid test can be used to assess the distortion of straight lines
- Fundoscopy. Drusen are the key finding.
Slit-lamp biomicroscopic fundus examination by a specialist can be used to diagnose AMD.
**Optical coherence tomography **is a technique used to gain a cross-sectional view of the layers of the retina. It can be used to diagnose wet AMD.
**Fluorescein angiography **involves giving a fluorescein contrast and photographing the retina to look in detail at the blood supply to the retina. It is useful to show up any oedema and neovascularisation. It is used second line to diagnose wet AMD if optical coherence tomography does not exclude wet AMD.
Management for Dry AMD
Refer suspected cases to an ophthalmologist for assessment and management.
Dry AMD
There is no specific treatment for dry age-related macular degeneration. Management focuses on lifestyle measure that may slow the progression:
- Avoid smoking
- Control blood pressure
- Vitamin supplementation has some evidence in slowing progression
Management of Wet AMD
Refer suspected cases to an ophthalmologist for assessment and management.
Anti-VEGF medications are used to treat wet age-related macular degeneration. V**ascular endothelial growth factor **is involved in the development of new blood vessels in the retina. Medications such as ranibizumab, bevacizumab and pegaptanib block VEGF and slow the development of new vessels. They are injected directly into the vitreous chamber of the eye once a month. They slow and even reverse the progression of the disease. They typically need to be started within 3 months to be beneficial.
What is Diabetic Retinopathy
Diabetic retinopathy is a condition where the blood vessels in the retina are damaged by prolonged exposure to **high blood sugar levels (hyperglycaemia) **causing a progressive deterioration in the health of the retina.
Hyperglycaemia leads to damage to the_____ ____ _____ and ________ cells . Increased vascular permeability leads to leakage from the blood vessels, blot haemorrhages and the formation of hard exudates. Hard exudates are __ __ deposits of lipids in the retina.
Hyperglycaemia leads to damage to the retinal small vessels and endothelial cells. Increased vascular permeability leads to leakage from the blood vessels, blot haemorrhages and the formation of hard exudates. Hard exudates are yellow/white deposits of lipids in the retina.
What is Microaneurysms and Venous Bleeding
Damage to the blood vessel walls leads to microaneurysms and venous beading. Microaneurysms are where weakness in the wall causes small bulges. Venous beading is where the walls of the veins are no longer straight and parallel and look more like a string of beads or sausages.
Damage to nerve fibres in the retina causes fluffy white patches to form on the retina called
cotton wool spots
What is Intraretinal microvascular abnormalities (IMRA)
is where there are dilated and tortuous capillaries in the retina. These can act as a shunt between the arterial and venous vessels in the retina.
What is Neovascularisation
Neovascularisation is when growth factors are released in the retina causing the development of new blood vessels.
Diabetic retinopathy can be split into two broad categories:
non-proliferative and proliferative
Non-proliferative is often called
background or pre-proliferative retinopathy as it can develop in to proliferative retinopathy.
A condition called ______ __________ also exists separate from non-proliferative and proliferative diabetic retinopathy.
A condition called diabetic maculopathy also exists separate from non-proliferative and proliferative diabetic retinopathy.
how is Diabetic Retinopathy classified
based on the findings on fundus examination.
Findings on examination
Non-proliferative Diabetic Retinopathy
**Mild:
Moderate:
Severe: **
Mild: microaneurysms
Moderate: microaneurysms, blot haemorhages, hard exudates, cotton wool spots and venous beading
Severe: blot haemorrhages plus microaneurysms in 4 quadrants, venous beading in 2 quadrates, intraretinal microvascular abnormality (IMRA) in any quadrant
Findings on examination
Proliferative Diabetic Retinopathy
- Neovascularisation
- Vitreous haemorrhage
Findings of Diabetic Maculopathy
- Macular oedema
- Ischaemic maculopathy
Complications of Diabetic Retinopathy
- Retinal detachment
- Vitreous haemorrhage (bleeding in to the vitreous humour)
- **Rebeosis iridis **(new blood vessel formation in the iris)
-
Optic neuropathy
* Cataracts
Management of Diabetic Retinopathy
- Laser photocoagulation
- Anti-VEGF medications such as ranibizumab and bevacizumab
- Vitreoretinal surgery (keyhole surgery on the eye) may be required in severe disease
What is Hypertensive Retinopathy
Hypertensive retinopathy describes the damage to the small blood vessels in the retina relating to **systemic hypertension. **This can be the result of years of chronic hypertension or can develop quickly in response to malignant hypertension. There are a number of signs that occur within the retina in response to the effects of hypertension in these vessels.
________ ________ or ________ ________ is where the walls of the arterioles become thickened and sclerosed causing increased reflection of the light.
Silver wiring or** copper wiring** is where the walls of the arterioles become thickened and sclerosed causing increased reflection of the light.
Eyelid Disorders
Eyelid Disorders
Eyelid Disorders
Eyelid Disorders
