Flashcards in OPTH - Eyes review Deck (28)
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?
What is scotoma?
Blind spot in vision
What is metamorphosia?
distortion of vision
Positive findings in Amsler grid usually indicate (what)?
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?
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 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
- 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)?
1.Progressive visual FIELD loss
2.Progressive increase in cup-to-disc ratio of optic disc.
3.Elevated intra-ocular pressure
- 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
- selective laser trabeculoplasty
- Trabeculectomy (alternative drainage path for aqueous)
Compare uveitic glaucoma & neovascular glaucoma
- Synechiae and inflammatory cells effect fluid dynamics within the anterior chamber
-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?
1. Mild: microaneurysms
- intraretinal haemorrhages
- hard exudates
- cotton wool spots
3. 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
4. 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
- 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.
- sudden eye pain
- nausea and vomiting
- other symptoms resulting from a sudden spike in intraocular pressure
= medical emergency.
Describe diabetic maculopathy (compare macular oedema & macular ischaemia)
1. Macular oedema
- leakage of fluid into foveal tissue
- lipid exudates adjacent to fovea
- Rx: macular (grid) laser, intravitreal anti-VEGF agents
2. 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
1. 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
2. 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
- "down and out" +/- mydriasis
- compressive (tumour, haemorrhage, aneurysm): commonly pupil involving (mydraisis)
- vascular (HTN, DM): commonly pupil sparing
- giant cell arteritis
- MRI/MRA, BP, BSL, lipid profile
Rx: depends on cause
Describe CN IV palsy
"tip, turn and tilt"
- trauma, tumour, vasculitis (GCA), microvascular disease
- old photos for congenital, bloods, neuroimaging
- according to cause
- prism in glasses