OPTH - Eyes review Flashcards
When should you try pinhole in a visual acuity test?
if VA 6/9 or worse
What is Marcus Gunn Pupil?
Relative Afferent Pupil Defect
What is Agyll Robertson Pupil?
Pupil constricts on accomodation (when focussed on an object close-up) but NOT to light.
What is Holmes Adie Pupil?
–Tonically dilated pupil that does not react to light
–Associated with damage to parasympathetic pupillary fibres
What are the 3 things you should examine in an eye?
- vision
- pupils
- pressure
What is scotoma?
Blind spot in vision
What is metamorphosia?
distortion of vision
Positive findings in Amsler grid usually indicate (what)?
macular pathology
Abnormal EOM may indicate:
- Cranial Nerve Palsy (CN III, IV or VI)
- Muscle entrapment (orbital fracture)
- Muscle infiltrate (Thyroid Eye Disease)
- Muscle Weakness (i.e. Guilian-Barre Miller-Fisher variant)
- Gaze Centre Dysfunction (horizontal gaze palsy, INO)
What is the most common cause for poor vision in humans?
Refractory error
Compare myopia & hypermetropia
Myopia: short sighted
- longer eye
- steeply curving cornea
- light is focused BEFORE hitting the retina
- Rx: concave lens to diverse light
Hypermetropia: long sighted
- shorter eye
- gradual curving cornea
- light is focused AFTER hitting the retina
- Rx: convex lens to converge light
What structures focus the light onto the retina in a normal eye?
Cornea (67%) & Lens (33%)
What is the fastest way to detect refractive error?
Pinhole
Pinhole obscures the light which has been inappropriately focussed onto the retina
What is presbyopia?
long-sightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.
Rx: reading glasses/bifocals
Describe cataract
- Px
- causes
- Rx
- Gradual decrease in visual acuity and increase in glare symptoms (over weeks to years)
- age-related, steroids, trauma, DM, Wilson’s diseae, ocular diseases (uveitis etc)
- Rx: cataract surgery.
Describe logistics of cataract surgery
- Visual improvement in >95% of operations performed
- Patients often admitted as a day-case
- Usually performed under topical or local anaesthesia
- Patient must be able to lie flat and still
- Post-operative antibiotic and steroid eye drops over 4 weeks
- Post-operative reviews: 1 day, 1 week, 1 month
What are the 3 major clinical features of primary open angle glaucoma (POAG)?
- Progressive visual FIELD loss
- Progressive increase in cup-to-disc ratio of optic disc.
- Elevated intra-ocular pressure
Note:
- Some people have high IOP but no evidence of glaucoma (Ocular Hypertension)
- Some people have features of glaucoma despite normal IOP (Sometimes referred to as Normal Tension Glaucoma)
Rx of primary open angle glaucoma (POAG)
- carbonic anhydrase inhibitors. E.g. Acetazolamide (Diamox) to decrease aqueous production
- Alpha agonist
Laser:
- selective laser trabeculoplasty
Surgical:
- Trabeculectomy (alternative drainage path for aqueous)
Compare uveitic glaucoma & neovascular glaucoma
Uveitic Glaucoma:
- Synechiae and inflammatory cells effect fluid dynamics within the anterior chamber
Neovascular glaucoma:
- Neovascularisation of the angle leads to reduced drainage of aqueous humor and increased intra-ocular pressure.
- Neovascularisation occurs secondary to ischaemia within the eye (e.g. in setting of CRVO or proliferative diabetic retinopathy)
What are the 2 types of diabetic retinopathy?
Non-prolifeative & proliferative
How do you grade non-proliferative diabetic nephropathy?
- Mild: microaneurysms
- Moderate:
- microaneurysms
- intraretinal haemorrhages
- hard exudates
- cotton wool spots - Severe (any one of the 4-2-1 rule)
- intraretinal haemorrhages in 4 quadrants
- venous bleeding in 2 quadrants
- intraretinal vascular abnormalities in 1 quadrant - Very severe
- 2 features from the 4-2-1 rule
Rx of proliferative diabetic retinopathy
Panretinal photocoagulation (laser)
- burns away areas of peripheral retina
- stops vessels on the retina from leaking
- decreases drive of BEGF production -> reduced neo-vascularisation
What is glaucoma? Describe briefly the 2 main categories.
a group of ocular (eye) disorders that result in optic nerve damage, often associated with increased fluid pressure in the eye (intraocular pressure) (IOP).
2 main categories: “open-angle” and “closed-angle” (or “angle closure”) glaucoma.
Open-angle chronic glaucoma
- painless
- develop slowly over time
- often asymptomatic until the disease has progressed significantly.
- Rx: glaucoma medication to lower the pressure, or with various pressure-reducing glaucoma surgeries.
Closed-angle glaucoma: - sudden eye pain - redness - nausea and vomiting - other symptoms resulting from a sudden spike in intraocular pressure = medical emergency.
Describe diabetic maculopathy (compare macular oedema & macular ischaemia)
- Causes
- Rx
- Macular oedema
- leakage of fluid into foveal tissue
- lipid exudates adjacent to fovea
- Rx: macular (grid) laser, intravitreal anti-VEGF agents - Macular ischaemia
- capillary non-perfusion at fovea
- enlarged foveal avascular zone & capillary drop out on fluorescein angiography
- Rx: none. Control BSL, BP, cholesterol.
Describe macular degeneration (compare dry & wet)
- causes & risk factors
- Rx
- Dry age-related macular degeneration
- Most common cause of blindness in people >50 in the developed world
- Risk factors: age, smoking
- Rx: quit smoking, low vision aids - Wet (neovascular) age-related macular degeneration
- Choroidal neovascularisation (classic feature)
- abnormal new vessels grow from choroid to retinal pigment epithelium
- vessels leak/bleed -> macular scarring
- linked to increased VEGF
- Rx: anti-VEGF agents (ranbizumab, bevacizumab) via intraocular injection, photodynamic therapy, macular laser
Describe CN III palsy
- Px
- cause
- Ix
- Rx
- “down and out” +/- mydriasis
Causes
- compressive (tumour, haemorrhage, aneurysm): commonly pupil involving (mydraisis)
- vascular (HTN, DM): commonly pupil sparing
- trauma
- giant cell arteritis
Ix:
- MRI/MRA, BP, BSL, lipid profile
Rx: depends on cause
Describe CN IV palsy
- Px
- cause
- Ix
- Rx
“tip, turn and tilt”
Causes:
- trauma, tumour, vasculitis (GCA), microvascular disease
Ix:
- old photos for congenital, bloods, neuroimaging
Rx:
- according to cause
- prism in glasses
Describe CN VI palsy
- Px
- cause
- Ix
- Rx
“Look left”
Causes:
- vascular, raised ICP, tumours, trauma, GCA
Ix: vascular risk factors, MRI
DDx:
- thyroid eye disease
- medial wall blow out fracture
Rx:
- according to cause
- Prisms +/- strabismus surgery
