Summary eye conditions: Front of eye Flashcards
front of eye conditions
Serious
- Glaucoma
- Anteiror uveitis
- Scleritis
- corneal abrasion
- herpes keratitis
less serious
- Cataracts
- Episcleritis
- Conjunctivits
- Subconjunctival haemorrhage
glaucoma background
optic nerve damage due to siginificant intraocular pressure
- usually caused by blockage of aqueous humour tyring to escape eye
- can also be caused by diabetic retinopathy when abnormal blood vessels grow out of the retina and bkock fluid from draining the eye
Types
- Open-angle (chronic)
- Close -angle (acute angle closure glaucoma)
anatomy related to glaucoma
Anatomy
- Vitreous chamber of the eye is filled with vitreous humour
- Anterior chamber (between the cornea and iris) and Posterior chamber (between the lens and the iris) are filled with aqueous humour -> supplies nutrient to the cornea
- Aqueous humour produced by ciliary body
- 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 general circulation
- Normal intraocular pressure :10-21mmg
- This pressure is created by the resistance to flow through the trabecular meshwork into the canal of schlemm
optic cupping and glaucoma
Increased intraocular pressure causes cupping of the optic discs
- In the centre of tha normal optic disc is the optic cup
- This is a small indent in the optic disc
- 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 -> cupping
- Optic cup over 0.5 the size of the optic disc is abnormal
pathophysiology behind acute angle-closure glaucoma
- ‘Pupillary block’- iris has bulged forward sticking to the lens when in mid-dilated position
- This seals off the trabecular meshwork from the anterior chamber preventing aqueous humour from being able to drain away -> continual build up of intraocular pressure
risk factor for Acute angle closure glaucoma
Long sightedness (hypermetropia)
- increasing age
- female
- asian ethnicity
- family history
trigger of AACG
Pupil mid-dilation can be caused by being in a dark room
Medications such as:
- anticholinergics (e.g. oxybutynin)
- antidepressants (SSRIs and TCAs)
- pupil-dilating drops (e.g. tropicamide). Topiramate use has been associated with bilateral AACG.
trigger of AACG
Pupil mid-dilation can be caused by being in a dark room
Medications such as:
- anticholinergics (e.g. oxybutynin)
- antidepressants (SSRIs and TCAs)
- pupil-dilating drops (e.g. tropicamide). Topiramate use has been associated with bilateral AACG.
Presentation of AACG
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
- Red-eye
- Teary
- Hazy cornea
- Decreased visual acuity
- Dilation of affected pupil
- Fixed pupil size
- Firm eyeball on palpation
investigations for AACG
Gonioscopy - assesses the angle between the iris and cornea
Tonometry - >30mmHg (Goldmann applanation tonometry)
management AACG
Lie patient flat on back (gravity helps bring lens away and oepn anterior chamber angle
- Pain relief
- Antiemetics
Acute
- Topical pilocarpine (muscarinic receptors) -> causes constriction of the pupil and ciliary muscle contraction -> help flow of aqueous humour
- IV Acetazolamide (carbonic anhydrase inhibitor) -> reduces production of aqueous humour
Subacute
- topical bete blockers e.g. timiolol
- topical sterouds
Definitive
- Peripheral iridotomy (laser hole through iris)
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 closure
**Peripheral vision loss **-> until tunnel vision
Other symptoms
- Fluctuating pain
- Headaches
- Blurred vision
- Halos around lights at night
investigations open angle closure
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
Treatment commenced >24mmHg
First line: Prostaglandin analogue eye drops (latanoprost)
- increase uveoscleral outflow
- eyelash growth
Other options
- Beta blockers (timolol)- reduced production of humour
- Carbonic anhydrase imhibitors (dorzolamide) -reduce produce of himour
- Sympathomimetics (brimonidine) reduce production and increased uveoscleral outflow
Definitive: Trabeculectomy
- 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.
cataracts background
Very common
- Where the lens in the eye becomes cloudy and opaque. *
- This reduces visual acuity by reducing the light that enters the eye.
risk factors for cataract
Increasing age
Smoking
Alcohol
Diabetes
Steroids
Hypocalcaemia
Congenital cataracts
occur before birth and are screened for using the red reflex during the neonatal examination.
Presentation of cataracts
asymmetrical
- Very slow reduction in vision
- Progressive blurring of vision
- Change of colour of vision with colours becoming more brown or yellow
- “Starbursts” can appear around lights, particularly at night time
A key sign for cataracts is the** loss of the red reflex.** The lens can appear grey or white when testing the red reflex. This might show up on photographs taken with a flash.
compare loss of vision caused by cataracts, glaucoma and age related macula degen
Cataracts: geenralised reduced visual acuity with starbursts
Glaucoma: peripheral loss of vision with halos around lights
Macula odema : central loss of vision with crooked or wavy appearance to straight lines
cataracts amangement
suregry -> removal of lens by breaking it into pieces and implanting an artifical lens
Complication: endopthalmitis
anterior uveitis
inflammation of the anterior part of the uvea (iris, ciliary blody and choroid) - sometimes called irits
Types
- Acute
- Chronic - more macrophages, less severe and >3months
presentation of anterior uveitis
- Dull, aching, painful red eye
- Ciliary flush (a ring of red spreading from the cornea outwards)
- Reduced visual acuity
- Floaters and flashes
- Sphincter muscle contraction causing miosis (constricted pupil)
- Photophobia due to ciliary muscle spasm
- Pain on movement
- Excessive tear production (lacrimation)
- Abnormally shaped pupil due to posterior synechiae (adhesions) pulling the iris into abnormal shapes
- A hypopyon is 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
examination findings for anterior uveitis (think workbook question
- abnormally shaped pipil due to posteiror synechia (adhesions) pulling the iris into abnormal shape -> gets stuck (iris sticks to pupil)
- Cells and flares
examination findings for anterior uveitis (think workbook question
- abnormally shaped pipil due to posteiror synechia (adhesions) pulling the iris into abnormal shape -> gets stuck (iris sticks to pupil)
- Cells and flares
Presentation
Scleritis usually presents with an acute onset of symptoms. Around 50% of cases are bilateral.
- Severe pain
- Pain with eye movement
- Photophobia
- Eye watering
- Reduced visual acuity
- Abnormal pupil reaction to light
- Tenderness to palpation of the eye
signs which differentiate scleritis from episcleritis
- Scleritis is much more painful than episcelritis
- Scleritis will not blanch with phenylephrine drops (episcleritis will improve redness)
- Scleritis is often bilateral , epsiscleritis is unilateral
episcleritis
Typically not painful but there can be mild pain
* Segmental redness (rather than diffuse). There is usually a patch of redness in the lateral sclera.
* Foreign body sensation
* Dilated episcleral vessels
* Watering of eye
* No discharge
investigations for corneal abrasion
- Fluorescein stain - stain abrasions or ulcers
- Slit lamp for more signifiant abrasions
investigations for herpes keratitis
- Staining with fluorescein will show a dendritic corneal ulcer. Dendritic describes the appearance of branching and spreading of the ulcer.
- Slit-lamp examination is required to find and diagnose keratitis.
- Corneal swabs or scrapings can be used to isolate the virus using a viral culture or PCR.
presentation of conjunctivitis
- Unilateral or bilateral
- Red eyes
- Bloodshot
- Itchy or gritty sensation
- Discharge from the eye
if allergic: may be seasonal, usually bilateral, antihistamines help
Presentation of subconjunctival haemorrhage
A subconjunctival haemorrhage appears as a patch of bright red blood underneath the conjunctiva and in front of the sclera covering the white of the eye.
It is painless and does not affect vision.
Often segmental -> clear border
