Ophthalmology

Question 1

most common cause of blindness in the UK

Answer 1

Age-related macular degeneration

Question 2

Age-related macular degeneration characteristics

Answer 2

Degeneration of the central retina (macula) is the key feature with changes usually bilateral. ARMD is characterised by degeneration of retinal photoreceptors that results in the formation of drusen which can be seen on fundoscopy and retinal photography. It is more common with advancing age and is more common in females.

Question 3

Age-related macular degeneration risk factors

Answer 3

advancing age (DUH)
smoking
family history
CVD

Question 4

two forms of macular degeneration?

Answer 4

traditionally -
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 know 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 worst prognosis

more updated classification:

1. early age-related macular degeneration (non-exudative, age-related maculopathy): drusen and alterations to the retinal pigment epithelium (RPE)
2. late age-related macular degeneration (neovascularisation, exudative)

Question 5

Clinical features of age related macular degeneration

Answer 5

Gradual worsening central visual field loss
Reduced visual acuity
Crooked or wavy appearance to straight lines

Question 6

signs/examinations for ARMD

Answer 6

distortion of line perception using amsler grid test
fundoscopy reveals the presence of drusen/macular scar (in dry ARMD)
reduced acuity using snellen chart

Question 7

investigations for ARMD

Answer 7

Slit-lamp biomicroscopic fundus examination is the initial investigation of choice.
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.

Question 8

management of ARMD

Answer 8

refer to ophthalmologist for assessment and management
dry ARMD -
Avoid smoking
Control blood pressure
combination of zinc with anti-oxidant vitamins A,C and E has some evidence in slowing progression
wet ARMD -
anti-VEGF agents (EG ranibizumab and typically need to be started within 3 months of diagnosis)
laser photocoagulation does slow progression of ARMD where there is new vessel formation, although there is a risk of acute visual loss after treatment so anti-vegf preferred

Question 9

what are the 4 key layers of the macula?

Answer 9

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.

Question 10

what is glaucoma and types

Answer 10

glaucoma is damage caused to the optic nerve due to raised 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: open-angle and closed-angle.

Question 11

what are the anterior and posterior chambers and what are they filled with?

Answer 11

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.

Question 12

normal flow of aqueous humour in the eye?

Answer 12

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 trabecular meshwork and into the canal of Schlemm. From the canal of Schlemm it eventually enters the general circulation.

Question 13

normal intraocular pressure?

Answer 13

The normal intraocular pressure is 10-21 mmHg. This pressure is created by the resistance to flow through the trabecular meshwork into the canal of Schlemm.

Question 14

pathophys of OAG

Answer 14

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.

Question 15

acute angle closure glaucoma pathophys

Answer 15

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. This is an ophthalmology emergency.

Question 16

fundoscopy sign of raised intraocular pressure

Answer 16

cupping of optic disk, ie, optic cup size>0.5 of optic disk

Question 17

risk factors for open angle glaucoma

Answer 17

increasing age
black ethnic origin
family history
myopia

Question 18

presentation of OAG?

Answer 18

often asymptomatic rise in intraocular pressure and diagnosed on routine screening at optometrist
peripheral vision loss and tunnel vision
halos around lights
blurred vision
gradual onset of fluctuating pain, headaches

Question 19

ix to measure intraocular pressure?

Answer 19

1. non-contact tonometry - less accurate but gives a helpful estimate for general screening purposes
2. goldmann applanation tonometry - gold standard

Question 20

management of OAG

Answer 20

treatment usually started at 24mmHg or above and pts are monitored closely for treatment response.

prostaglandin analogue eyedrops (eg latanoprost) - 1st line. increase uveoscleral outflow.

other meds -

1. beta blockers (eg timolol) - reduce aqueous humour production
2. carbonic anhydrase inhibitor (eg dorzolamide) - reduce aqueous humour production
3. Sympathomimetics (e.g. brimonidine) reduce the production of aqueous fluid and increase uveoscleral outflow

Trabeculectomy surgery may be required where eye drops are ineffective.

Question 21

side effects of latanoprost eye drops?

Answer 21

pigmentation of of eyelids and iris

eyelash growth

Question 22

complication of acute angle closure glaucoma

Answer 22

Acute angle-closure glaucoma is an ophthalmology emergency. Emergency treatment is required to prevent permanent loss of vision.

Question 23

RFs for acute angle closure glaucoma

Answer 23

increasing age
female sex
family hx
Chinese and East Asian ethnic origin.
Shallow anterior chamber

certain medications -
Adrenergic medications such as noradrenalin
Anticholinergic medications such as oxybutynin and solifenacin
Tricyclic antidepressants such as amitriptyline, which have anticholinergic effects

Question 24

presentation of acute angle closure glaucoma

Answer 24

pt generally unwell in themselves
short hx of  - 
- severely painful red eye
- blurred vision
- halos around lights
- associated headache, N&V

Question 25

signs of acute angle closure glaucoma

Answer 25

red teary eye
dilatation of pupil in affected eye
fixed pupil size
reduced visual acuity
hazy cornea
firm eyeball on palpation

Question 26

management of acute angle closure glaucoma

Answer 26

initial management in primary care-

1. call ambulance and same day assessment by ophthalmologist
2. if delay in admission/whilst waiting for ambulance -
   - lie pt on their back without pillow
   - pilocarpine eye drops (2% for blue eyes and 4% for brown) (mitotic agent)
   - acetazolamide 500mg PO
   - analgesia and antiemetic if required

secondary care management - 
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 
Dorzolamide 
Brimonidine 

Laser iridotomy is usually required as a definitive treatment.

Question 27

what is the uvea

Answer 27

uvea involves the iris, choroid layer and the ciliary bodies

Question 28

what is anterior uveitis and what causes it?

Answer 28

It involves inflammation and immune cells in the anterior chamber of the eye. This is usually caused by an autoimmune process but can be due to infection, trauma, ischaemia or malignancy.

it can be acute or chronic. chronic usually lasting >3 months

Question 29

what conditions is anterior uveitis associated with?

Answer 29

acute anterior uveitis - HLA B27 related conditions:

• ankylosing spondylitis
• reactive arthritis
• IBD

chronic anterior uveitis -

• syphillis
• TB
• herpes
• lyme disease
• sarcoidosis

Question 30

presentation of anterior uveitis

Answer 30

unilateral symptoms - 
ciliary flush
lacrimation
irregularly shaped pupil (due to posterior synechiae (adhesions))
small constricted pupil
floaters and flashes in vision
ophthalmoplegia
Dull, aching, painful red eye
reduced visual acuity
hypopyon (a collection of white blood cells in the anterior chamber, seen as a yellowish fluid collection settled in front of the lower iris, with a fluid level)

Question 31

management of anterior uveitis

Answer 31

if potential for sight loss- same day referral to ophthalmologist.

some management options -
steroids
Cycloplegic-mydriatic medications such as cyclopentolate or atropine eye drops. Cyclopentolate and atropine are antimuscarinic medications that blocks to the action of the iris sphincter muscles and ciliary body. These dilate the pupil and reduce pain associated with ciliary spasm by stopping the action of the ciliary body.
Immunosuppressants such as DMARDS and TNF inhibitors
Laser therapy, cryotherapy or surgery (vitrectomy) are also options in severe cases.

Question 32

https://www.minerva.shef.ac.uk/minerva/med/pages/phase3b/phase3b_modules/3b_speciality/speciality_ophintro.php

Answer 32

https://www.minerva.shef.ac.uk/minerva/med/pages/phase3b/phase3b_modules/3b_speciality/speciality_ophintro.php