Opthal - Preading Flashcards
What are the 3 C’s to remember when describing the optic disc on fundoscopy?
-
Cup
- Cup-disc ratio - think of optic nerve as doughnut with blood vessels travelling through the middle
- ↑ cup:disc ratio (e.g. 0.9) = nerve loss/degen making cup larger and disc smaller e.g. glaucoma
- Normal cup:disc ratio = 0.3
-
Contour
- Describe edge between optic nerve and retina
- Blurred contour = swollen nerve
-
Colour
- Normal = orange - pink
-
Pale - glaucoma, ON or optic neuropathy (NIGHT TIC)
- Neuritis
- Ischaemic
- Granulomatous
- Hereditory
- Traumatic
- Toxic
- Irradiation
- Compression
What technique can be used to visualise the blood vessels in the eye?
Fundus fluorescein angiography (FFA)
(image = normal)
- fluorescein injected into vein
- camera excites dye –> provides pictures
What type of imaging can be used to better view the retina?
optical coherence tomography (OCT)
(image = normal)
- provides cross-sectional image of back of eye
- shows layers of retina + pathologies
What additional questions / areas of history are needed in an opthalmic history?
-
HPC:
- Any eye pain or redness?
- One or both eyes?
- Noticed any change in peripheral vision / central vision?
- Up to date pair of glasses
-
Past opthalmic history:
- previous surgery
- short / longsighted
- contact lenses or glasses worn or worn previously?
-
DH:
- Anti-TB medication (e.g. ethambutol) SI include: ON
- Amiodarone (antiarrhythmic) - SI include: ON, corneal deposits (causing corneal opacities)
- Chloroquine / hydroxychloroquine (DMARDs) - SI include: retinopathy / bull’s eye retinopathy / maculopathy (see pic)
-
FHx:
- Glaucoma
- Dystrophy e.g. cone dystrophy
- Blindness
-
SH:
- Occupation
- Driving (DVLA requies that you have at least 6/12 in one eye in order to drive)
What are the medical terms of short-sighted and long-sighted?
-
Short-sighted = myopia
- Risk of retinal detatchment
-
Long-sighted = hypermetropia
- Risk of acute glaucoma
What signs on the retina can indicate hypertension?
Hypertensive retinopathy signs usually develop LATE in disease
-
Papilloedema (optic disc swelling)
- Blurred contour of optic disc margin
- Paton’s lines - concentric/radial lines cascading from optic disc
- Retinal haemorrhages (flame haemorrhages)
- Yellow hard exudates - lipid deposits with sharp margins
-
Cotton wool spots - white spots which represent swelling of retinal nerve fibres due to microinfarctions
- Often near optic disc
Name some occular medical emergencies.
(5 listed)
- Central retinal artery occlusion (CRAO)
- Orbital cellulitis
- Retinal detachment
- Acute-angle closure glaucoma
- Giant cell arteritis
If the patients vision was 6/12 with corrected lenses what should be your next course of action?
- Refer to opthalmologist
- Send to opticians for new lenses
- Re-test with pin-holes
Re-test with pin holes
What is the purpose of pin-hole testing?
Pin holes allow only central rays of light in to they eye which means that it will correct for a certain amount of refractive error allowing you to differentiate between:
- Refractive errors (in which case sent to the opticians)
- Eye pathology (in which case refer to the ophthalmologist)
Note: record visual acuity with glasses/lenses and record if PH was done e.g. left eye (with glasses) PH 6/12
Which of the following are correct.
The retina consists of:
- The retinal pigment epithelium, a multi-layer group of cells
- Photoreceptors called rods and cones
- An inner and outer plexiform layer
- 9 layers
Photoreceptors called rods and cones
&
An inner and outer plexiform layer
- The retinal pigment epithelium (farthest from vitrious body) is a MONO-layer of cells
- The retina has 10 layers total
Which of the following are correct.
The cornea:
- Consists of 5 layers
- Is avascular
- Is the only structure in the eye responsible for focusing light (refraction of light)
- Is composed of regular arranged collagen fibres
- Consists of 5 layers
- Is avascular
- Is composed of regular arranged collagen fibres
- Sclera = irregular alignment of collage fibres
Patients describe eye pain as the following - what do they indicate?
- Grittiness, dryness eyes feel tired / want to close
- Sharp / stabbing pain “like needles”
- Dull ache
- Grittiness, dryness eyes feel tired / want to close
- Dry eye
- Sharp / stabbing pain “like needles”
- Ocular surface problem
- Dull ache - like toothache
- Uveitis /↑ IOP / scleritis
For each lesion location describe the visual field loss.
Briefly describe the procedure for fundoscopy.
For each eye:
- Check equipment
- Check opthalmoscope is charged
- Dilate eyes as per hospital guidelines
- Dim lights where possible
- Set ophthalmoscope lens dial to 0
- Check for red reflex – no red reflex, no fundoscopy!
- Move in closer and look for retinal vessel
- Follow retinal vessel to optic disc
- Cup – colour – contour
- Follow 4 vascular arcades
- Ask patient to look up, down, left and right to check for peripheral changes
- Ask the patient to look directly in to the light to check the macular
What are the normal visual field ranges in each direction?
- Superior - 50 degrees
- Nasally - 60 degrees
- Inferior - 70 degrees
- Temporally - 90 degrees
Name some causes of ‘central’ visual field loss.
- Age-related macular degeneration
- Optic neuropathy
- Retinal artery occlusion
- Macular holes - small break in macula
- Cone dystrophies - inherited loss of cone cells
- Leber’s hereditary optic neuropathy - mitchondrially inherited degen of retinal ganglion cells
Name some causes of peripheral visual loss.
- Glaucoma (angle-closure glaucoma and open-angle glaucoma)
- Retinal detatchment
- Retinitis pigmentosa - genetic, progressive loss of rod cells (often followed by loss of cone cells)
-
Chorioretinitis - inflammation of the choroid (pigmented vascular coat of the eye) + retina
- Type of posterior uveitis
- Cause = often toxoplasma gondii or cytomegalovirus infections (seen in immunodeficient), but also; syphilis, sarcoidosis, TB
- Branch retinal artery occlusion
What is a scotoma?
Scotoma = visual field defect surrounded by normal visual field
- Can begin as gradual enlargement of blind spot
- Relative scotoma = area where objects of low luminance can’t be seen but large / bright objects can
- Absolute scotoma = nothing seen in affected area of visual field
What pathologies could cause the following visual field defects?
(see image)
How many vascular arcades supplying the retina are there?
4
- Superior temporal
- Superior nasal
- Inferior temporal
- Inferior nasal
Dilating medication is often used prior to examination with opthalmoscope.
Name 3 pupil dilating agents.
- Tropicamide 1% - anti-muscarinic
-
Cyclopentolate 1% - muscarinic ACh-R antagonist
- These dilating drops can be used in children
- Phenylephrine 2.5% - sympathomimetic
Note: caution not to use this in patients at risk of or Hx of glaucoma
