OPTH - Eyes review Flashcards Preview

â–º Med Misc 43 > OPTH - Eyes review > Flashcards

Flashcards in OPTH - Eyes review Deck (28):
1

When should you try pinhole in a visual acuity test?

if VA 6/9 or worse

2

What is Marcus Gunn Pupil?

Relative Afferent Pupil Defect

3

What is Agyll Robertson Pupil?

Pupil constricts on accomodation (when focussed on an object close-up) but NOT to light.

4

What is Holmes Adie Pupil?

–Tonically dilated pupil that does not react to light
–Associated with damage to parasympathetic pupillary fibres

5

What are the 3 things you should examine in an eye?

1. vision
2. pupils
3. pressure

6

What is scotoma?

Blind spot in vision

7

What is metamorphosia?

distortion of vision

8

Positive findings in Amsler grid usually indicate (what)?

macular pathology

9

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)

10

What is the most common cause for poor vision in humans?

Refractory error

11

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

12

What structures focus the light onto the retina in a normal eye?

Cornea (67%) & Lens (33%)

13

What is the fastest way to detect refractive error?

Pinhole

Pinhole obscures the light which has been inappropriately focussed onto the retina

14

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

15

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.

16

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

17

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

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)

18

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)

19

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)

20

What are the 2 types of diabetic retinopathy?

Non-prolifeative & proliferative

21

How do you grade non-proliferative diabetic nephropathy?

1. Mild: microaneurysms
2. Moderate:
- 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

22

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

23

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.

24

Describe diabetic maculopathy (compare macular oedema & macular ischaemia)
- Causes
- Rx

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.

25

Describe macular degeneration (compare dry & wet)
- causes & risk factors
- Rx

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

26

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

27

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

28

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

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