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H+N - C > Common Conditions of the Eye > Flashcards

Common Conditions of the Eye Flashcards

1
Q

How does nuclear sclerosis affect vision?

A

Makes objects appear less clear, and also makes patient see more of the red spectrum

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2
Q

Give an overview of some of the common conditions affecting the eye

A
  • Cataracts (lens)
  • Glaucoma (aqueous humor outflow)
  • Ulcers and dystrophies (cornea)
  • Uveitis (uvea)
  • Lid and conjunctivae problems
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3
Q

What is the epidemiology of cataract?

A

Lens opacification

about 30% of people >65 had some opacity.
Estimated incidence each year of 225,000 new cases of visually impairing cataracts

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4
Q

Why do cataracts develop?

A
  • Older (embryological, foetal) fibres are never shed - compacted in the middle
  • No blood supply to lens, which depends entirely on diffusion for nutrition
  • Absorbs harmful UV rays preventing them from damaging retina but in the process, get damaged themselves.
  • Damaged lens fibres -> opaque -> CATARACT
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5
Q

Whats the difference between an immature cortical cataract and a mature cataract?

A

Immature cortical cataract:

  • Seen as spoke like opacities
  • Periphery of lens so only effects vision when pupil dilated
  • “Struggle to drive at night”

Mature cataract:

  • Symptomatic
  • Centre of lens effected
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6
Q

Give some examples of secondary cataracts

A

Steroid-induced cataract (may involve lens capsule and anterior part of lens)

Traumatic cataract
-odd shape

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7
Q

What causes a nuclear sclerosis type of cataract?

A

Age related change in the density of crystalline lens nucleus that occurs in all older animals.

It is caused by compression of older lens fibres in the nucleus by new fibre formation

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8
Q

What is a Sutural + Zonular cataract?

A

Types of childhood cataract formed due to opacification of certain zones of the lens in utero.

Maternal infection may cause.

Only centre of lens affected as the outer fibres grow later

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9
Q

What is the management of cataracts?

A

EYE DROPS DO NOT TREAT CATARACT

Surgery

  • (Day case) small incision
  • Lens capsule opened
  • Cataractous lens removed by emulsification (phacoemulsification)
  • Plastic lens placed in capsular bag

Lens implant after cataract surgery (PCIOL) = Posterior Chamber Intra Ocular Lens

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10
Q

What is the pathway for aqueous humour from production to reabsorption?

A

Produced by ciliary body.
Flows between iris and lens into anterior compartment.
Filtered by trabecular meshwork and into Schlemm’s canal.
Inters venous system

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11
Q

What is Glaucoma?

A

Raised intraocular pressure (IOP)

Caused by blockage of AH flow at any stage of its cycle

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12
Q

What is the epidemiology of Glaucoma including most common form?

A

2nd most common global cause of blindness

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13
Q

What is the most commonly seen form of primary glaucoma?

A

Primary Open Angle Glaucoma (POAG)

  • 978 per 100,000 of population aged 40-89
  • Bilateral
  • Patient can be asymptomatic for a long period of time
  • Picked up on routine eye exams
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14
Q

What are the consequences of raised IOP?

A

Pressure on nerve fibres on surface of retina -> die out -> visual field defects

Pressure on optic nerve head as nerve fibres die out. When seen by ophthalmoscopy - optic disc appears unhealthy, pale and cupped.

This results in altered field of vision.

Ultimately all nerve fibres are lost, which results in blindness

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15
Q

What is the triad of signs for the diagnosis of glaucoma?

A
  1. Raised IOP
  2. Visual field defects
  3. Optic disc changes on opthalmoscopy
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16
Q

What is the management of POAG?

A

Eye drops to decrease IOP

  • Prostaglandin analogues
  • Beta-blockers
  • Carbonic anhydrase inhibitors

Laser trabeculoplasty

Trabeculectomy surgery

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17
Q

What is angle closure glaucoma?

A

Sudden onset, painful, vision lost/ blurred; HEADACHES (often confused with migraine)

Red eye, core often opaque as raised IOP drives fluid into cornea

AC shallow, and angle is closed

Pupil mid-dilated

IOP severely raised

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18
Q

How do you manage an acute episode of angle closure glaucoma?

A
  1. Decrease IOP
    - –IV infusion with or without oral therapy (carbonic anhydrase inhibitors)
    - –Analgesics, antiemetics
    - –Consider eye drops (pilocarpine)
    - –If no contraindication beta-blocker drops such as timolol
    - –Steroid eye drops (dexamethasone)
  2. Iridotomy (laser) BOTH EYES to bypass blockage
19
Q

Give an example of a carbonic anhydrase inhibitor

A

Acetazolamide

20
Q

Why does the angle close in angle closure glaucoma

A
  1. functional block in a small eye (large lens)
  2. Mid dilated pupil -> periphery of iris crowds around angle and outflow is obstructed
  3. Iris sticks to pupillary border (synechia) which prevents reaching AC. Leads to iris ballooning anteriorly and obstructing angle
21
Q

What is Iridotomy?

A

Tiny hole in iris of BOTH EYES.
(both eyes will be larger compared to size of lens)

Allows AH to drain through iris

22
Q

Summarise open angle glaucoma

A

In open angle glaucoma the drainage through the trabecular meshwork is blocked (in most cases).

This leads to gradual, painless build up of IOP.

This type of glaucoma is called Primary Open Angle Glaucoma (POAG)

23
Q

Summarise Angle Closure Glaucoma

A

In angle closure glaucoma, some event on a predisposed eye leads to the peripheral iris blocking the angle therefore AH can’t drain.

So the increase in IOP is SUDDEN leading to a red eye and severe pain.

Patient usually presents as an emergency

24
Q

What are the two types of cornea pathology?

A

Inflammatory:
-e.g. corneal ulcers

Non-inflammatory
-e.g. Dystrophies

25
Q

Management of some corneal pathologies that cause opacification of the cornea are by corneal transplantation.
What is this procedure called?

A

Keratoplasty

26
Q

What are the causes of corneal ulcer (corneal inflammatory pathology)?

A

Infectious:

  • Viral/ bacterial/ fungal infection of cornea
  • Adenovirus is a very common cause (start with conjunctivitis which spreads to cornea)
  • Needs aggressive management to prevent spread, scarring

Non-infectious:

  • Trauma
  • Corneal degenerations
  • Dystrophy
27
Q

What are corneal dystrophies?

A

Group of diseases affecting the cornea which are:

  • Bilateral
  • Opacifying
  • Non-inflammatory
  • Mostly genetically determined
  • Sometimes due to accumulation of substances such as lipids within the cornea
28
Q

What is the clinical presentation of corneal dystrophies?

A

First to fourth decade

Most commonly - decreased vision

Start in one of the layers of the cornea and spread to the others

29
Q

Describe lattice (stromal) dystrophy

A

Type of corneal dystrophy

  • The classic type is autosomal dominant
  • Deposition of amyloid material in corneal stroma
  • Patient presents with eye irritation, photosensitivity, pain, blurred vision

Examination shows bilateral criss-crossing opacities in the storm of the cornea

Treatment = manage symptoms, in late stages corneal transplant

30
Q

Describe Fuch’s endothelial dystrophy

A

Asymmetrical bilateral progressive oedema (= swelling sue to accumulation fo fluid) of the cornea.

Occurs in the elderly (60-70 years of age)

The dystrophy is due to destruction and death of the endothelial cells.

A stage comes when the number of functioning endothelial cells falls below the critical number required to maintain the cornea clear -> oedema -> opacification

31
Q

What is the Rx of Fuch’s endothelial dystrophy?

A

Initially symptomatic, later corneal transplant

32
Q

Describe the Uvea

A

Vascular layer of the eyeball

Ciliary body
-Suspends the lens and produces AH

Choroid
-Supplies blood to outer layers of retina

Iris
-Controls the diameter of the pupil and thereby controls the amount of light rays entering the eyeball

33
Q

What is Uveitis?

A

Inflammation of Uvea

34
Q

What are the types of Uveitis?

A

Anterior Uveitis:

  • Iris with or without ciliary body inflammed
  • Easy to see

Intermediate Uveitis:

  • Ciliary Body Inflammed
  • Very hard to see

Posterior Uveitis:

  • Choroid inflammed
  • Can see
35
Q

what are the causes of Uveitis?

A

Isolated illness

Non-infectious autoimmune causes
-e.g. presence of HLA-B27 predisposes to anterior Uveitis

Infectious causes
-Chronic diseases such as TB

Associated with systemic diseases
-e.g. ankylosing spondylosis

36
Q

What is the pathology of anterior Uveitis?

A

An inflammed anterior uvea (iris) leaks plasma and white blood cells into the aqueous humour

These are seen during slit lamp examination as a hazy anterior chamber and cells deposited at the back of the cornea
(cells in AC may settle inferiorly (“hypopyon”)

The eye is red, painful, with visual loss

37
Q

What is the pathology in intermediate Uveitis?

A

In intermediate uveitis the ciliary body is inflammed and leaks cells and proteins

This leads to a hazy vitreous

Patient complains of “floaters” or hazy vision

38
Q

What is the pathology in intermediate Uveitis?

A

In posterior uveitis the choroid is inflammed.

Since the choroid sits under the retina, the inflammation frequently spreads to the retina causing blurred vision

39
Q

What is the conjunctiva?

A

thin vascular membrane that covers inner surface of eyelids and loops back over sclera

Does not cover the cornea

40
Q

What gland do all hair follicles have?

A

Sebaceous gland

41
Q

What is the pathology of the eyelids?

A

Stye or hordeolum

  • External = affecting the sebaceous glands of an eyelash
  • Internal = affecting the meibomian glands

Chalazion

42
Q

What is a stye?

A

An external stye (hordeolum externum) occurs due to infection of the hair follicle of the eyelash

An internal stye (hordeuolum internum) occurs due to blockage and infection of the Meibomian glands

Redness, actually tender

43
Q

What is a chalazion?

A

Occurs due to a chronic inflammation of the meibomian gland within the tarsal plate

Hard, non-tender

Rx: warm compress, eyelid hygiene, may need surgical incision and curettage

44
Q

What is conjunctivitis?

A

Self-limiting bacterial or viral infection of the conjunctiva.

Red, watering eyes, discharge +

No loss of vision as long as infection does not spread to cornea

Rx = antibiotic eye drops if likely to be bacterial

H+N - C (17 decks)

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