4- Ophthalmology (Gradual deterioration of vision) Flashcards
causes of gradual loss of vision
Front of the eye problems
- Cataract
o Age related
o Pre- senile (steroid, diabetes, trauma, uveitis) - Primary open angle glaucoma
Back of the eye problems
- Age related macula degeneration
- Diabetic eye disease
o Retinopathy (nonproliferative, proliferative)
o Maculopathy (oedematous, ischaemic) - Hypertensive retinopathy
- Thyroid eye
- Presbyopia
Types of glaucoma summary
- Open-angle
- Closed-angle (acute angle closure)
Open-angle summary
- Gradual increase in resistance through trabecular meshwork
- Makes it more difficult for aqueous humour to flow through the meshwork and exist the eye
- Pressure slowly build within the eye
- Slow and chronic onset of glaucoma
Closed-angle (acute angle closure)
Emergency
- Iris has bulged forward and sealed off the trabecular meshwork from the anterior chamber preventing aqueous humour from being able to drain away -> continual build up of pressure
- Ophthalmology emergency
Open angle glaucoma
Background
- Glaucoma refers to optic nerve damage that is caused by significant rise in intraocular pressure
- Raised intraocular pressure is caused by blockage in aqueous humour trying to escape the eye
- Gradual
Risk factor/causes
open angle glaucoma
- Increasing age
- Family history
- Black ethnic origin
- Near-sightedness (myopia)
Pathophysiology open angle glaucoma
- Gradual increase in resistance through trabecular meshwork
- Makes it more difficult for aqueous humour to flow through the meshwork and exist the eye
- Pressure slowly build within the eye
- Slow and chronic onset of glaucoma
presentation of open angle glaucoma
- Rise in intraocular pressure is asymptomatic from a long period of time
- Diagnosed often by routine screening
- Affects peripheral vision first -> the peripheral vision closes in until they experience tunnel vision
- Other
o Fluctuating pain
o Headaches
o Blurred vision
o Halos appearing around lights in the evening
open angle glaucoma and peripheral vision
- Peripheral vision goes first
- Later stages tunnel vision
investigations for open angle glaucoma
- measuring intraocular pressure
- Fundoscopy
- Visual field assessment (peripheral vision loss)
measuring intraocular pressure
Non- contact tonometry(more crude method)
- For estimating – less accurate
- Puff of air shot at cornea and corneal response to air measured
Goldmann applanation tonometry(gold standard)
- 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 the intraocular pressure
goldman applantion tonometry findings
fundoscopy and open angle glaucoma
look for optic disc cupping and optic nerve health
aim of management of open angle glaucoma
Aim is to reduce intraocular pressure.
when is treatment started with open angle glaucoma
Treatment commenced if pressure of 24mmHg or above
first line management of open angle glaucoma
First line: Prostaglandin analogue eye drops e.g. latanoprost
- Increase uveoscleral outflow
- Side effects: eyelash growth, eyelid pigmentation
- Iris pigmentation (browning)
Other options
- Beta-blockers (e.g. timolol) reduce production of aqueous humours
- Carbonic anhydrase inhibitors e.g. dorzolamide to reduce production of aqueous humour
- Sympathomimetics e.g. brimonidine, reduce the production of the aqueous fluid and increase uveoscleral outflow
surgical management of open angle glaucoma
Trabeculectomy – if eye drops ineffective
- Creating new channels from the anterior chamber, through the sclera to a location under the conjunctiva -> causes a ‘bleb’ under the conjunctiva where aqueous humour drains- it then reabsorbed from this bled into general circulation
Cataracts
Background
- Where the lens in the eye becomes cloudy and opaque
- Reduces visual acuity by reducing the light that can enter the eye (Cataracts are thought to increase intraocular light scatter, which can decrease retinal image contrast and adversely affect contrast sensitivity, which is affected far more than visual acuity in patients with cataracts.)
Pathophysiology
of cataracts
Proteins in the lens of the eye breakdown and aggregrate -> cloudy
types of cataract
age related
pre-senile
age related cataracts risk factors
Most develop over years with advanced age in the presence of risk factors
o Smoking
o Alcohol
o Diabetes
o Steroids
o hypocalcaemia
pre-senile cataracts risk factors
- Congenital (occurs before birth and are screening for using the red reflex during neonate examination)
Genetic e.g. galactosaemia
Infections e.g. rubella - Steroids
- Diabetes
- Trauma
- Uveitis
presentation of cataracts
Presentation
- Asymmetrical
- Slow reduction in vision acuity
- Progressive blurring of vision
- Change of colour of vision with colours becoming more brown or yellow
- ‘starbursts’ can appear around lights
examintion for cataracts
- Loss of red reflex
- Lens appear grey or white when testing red reflex
manageemnt of cataracts
Management
- Conservative approach if symptoms manageable
- Cataract surgery
o Involves drilling and breaking the lens into pieces, removing the pieces and then implanting an artificial lens
Cataract surgery complication:
Endophthalmitis
It is inflammation of the inner contents of the eye, usually caused by infection. It can be treated with intravitreal antibiotics injected into the eye. This can lead to loss of vision and loss of the eye itself.
age related macular degeneration
- Condition where degeneration of the macula causes progressive deterioration in vision
- Most common cause of blindness in the UK
types of age related macular degeneration
o Dry (90%)
o Wet (10%)- worse prognosis
pathophysiology of age related macular degeneration
Pathophysiology
The macula is made up of four key layers
- Choroid layer (bottom) -> blood vessels that supply the macula
- Drusen in Bruchs membrane
- Retinal pigment epithelium
- Photoreceptors e.g. rods and cones
Traditionally two forms of macular degeneration are seen:
dry macular degeneration
- 90% of cases
- also known as atrophic
- characterised by drusen - yellow round spots in Bruch’s membrane
wet macular degeneration
- 10% of cases
- also known as exudative or neovascular macular degeneration
- characterised by choroidal neovascularisation
- leakage of serous fluid and blood can subsequently result in a rapid loss of vision
carries the worst prognosis
- A key chemical that stimulates the development of new vessels if VEGF -> target of medications that treat wet AMD
risk factors for age related macula degeneration
Risk factors
- Age
- Smoking
- White or Chinese ethnic origin
- Family history
- CVD disease
presentation of age related macula degeneration
Presentation
* 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 for age related macula degeneration
- Reduced acuity using Snellen chart
- Scotoma (central patch of vision loss)
- Amsler grid test can be used to assess the distortion of straight lines
- Fundoscopy – Drusen= key finding
Investigations
for age related macular degeneration
- Fundoscopy- Drusen
- Slit lamp biomicroscopic fundus examination
- Optical coherence tomography
- Fluorescein angiography
age related macular degeneration prevalence
leading caus eof severe, irreversible vision loss in people over 55
Management
Dry AMD
- No specific treatment
- Focusses on lifestyle measures that may slow progression
o Avoid smoking
o Control blood pressure
o Vitamin supplementation
management wet AMD
Anti-VEGF medication e.g. ranibizumab
- to reduce development of new blood vessels in the retina
- injected into vitreous chamber once a month
- can slow down and even reverse progression of disease
- should be started within 3 months to be beneficial
