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Duke Elder > Uvea and Sclera > Flashcards

Uvea and Sclera Flashcards

1
Q

What are the 3 components of the uvea

A

The choroid, iris and ciliary body

Considered together as the uveal tract

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2
Q

What is the sclera?

A

The sclera is the white part at the front of the eye, wrapping all the way to the back and terminating at the optic nerve.

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3
Q

Revise

A
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4
Q

Anatomy of the choroid

A

The choroid is a highly vascular, pigmented structure extending from the ora Serrata to the optic disc.

It provides vascular supply and absorbs reflecting light. The choroid gets thinner as you move anteriorly.

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5
Q

Layers of the Choroid
(external to internal)

A
  1. Haller’s layer (large vessels)
  2. Sattler’s layer (medium vessels)
  3. Choriocapillaris (capillaries)
  4. Bruch’s membrane (basement membrane)
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6
Q

What is the suprachoroidal space

A

A potential space that sits on top of Haller’s layer. It separates the sclera from the choroid.

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7
Q

Anatomy of the Iris

A

The iris is the anterior part of the uveal tract. It extends from the anterior chamber angle to the pupil. Its muscles are responsible for changing the size of the pupil. The iris is the coloured part of the eye when you’re looking at someone directly.

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8
Q

Dimensions of the iris

A
  • 12mm diameter
  • 37mm circumference
  • 2mm thickness
  • The anterior chamber volume is 200uL compared to the posterior chamber at 60uL
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9
Q

Iris Zones

A

When looking at someone’s iris head-on, the visible anterior border is described in 3 zones

  • The inner pupillary zone contains the sphincter pupillae muscle
  • The outer ciliary zone contains the dilator pupillae muscle
  • The collarette is the middle zone used for anatomical division
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10
Q

Muscles of the iris

A

The sphincter pupillae is responsible for pupil constriction and is innervated by postganglionic parasympathetic short ciliary fibres of CN3

The dilator pupillae is responsible for pupil dilations and is innervated by sympathetic branches of the ciliary nerves

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11
Q

Blood Supply to the iris

A
  • Major circle comprised of 2 long posterior and 7 anterior ciliary arteries
  • Minor circle is formed at the level of the collarette
  • Iris vessels are not fenestrated, they do not leak during FFA
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12
Q

Layers of the Iris

A
  1. Anterior border
  2. Stroma
  3. Dilator pupillae
  4. Posterior pigment epithelium
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13
Q

Structure of the iris

A
  • The anterior border is composed of modified stromal cells with crypts
  • Koganei are clumps of pigmented macrophages found in the iris stroma
  • The sphincter pupillae muscle lies within the stroma
  • The posterior pigmented epithelium is cuboidal
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14
Q

Anatomy of the Ciliary Body

A

A muscular secretory structure involved in accommodation, aqueous production, and the blood-aqueous barrier.

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15
Q

Divisions of the Ciliary Body

A

Anterior functional part → pars plicata
Posterior non-functional part → pars plana

There are around 70 major ciliary processes in the pars plicata which are involved in aqueous secretion

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16
Q

What is ‘snow banking’

A

Snow banking is deposition on the pars plana of the ciliary body, a characteristic clinical sign of uveitis

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17
Q

Layers of the Ciliary Body

A

Epithelium, stroma and muscles:

The epithelium is bilaminar (arranged apex to apex) and cuboidal.
* The outer layer is pigmented.
* The inner layer in non-pigmented and produces aqueous.

There are 3 muscles: longitudinal (outermost), oblique, circular (innermost)

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18
Q

Nerve Supply to the choroid

A

PNS: Edinger Westphal nucleus of CN III → ciliary ganglion → short ciliary nerves → contract ciliary body and laxes zonular fibres

SNS: Hypothalamus → spinal cord → superior cervical ganglion → ICA plexus or by joining V1 → long ciliary nerves → relax the ciliary body and tenses zonular fibres

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19
Q

Anatomy of the Sclera

A

The sclera stretches from the iris at the front of the eye, to the optic nerve at the back. It is a tough outer coat of connective tissue.

The episclera is another layer of connective tissue which sits on top of the sclera. It is highly vascular and supplies the sclera with nutrients.

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20
Q

Where is the scelera thickest vs thinnest

A
  • Thickest at the optic nerve
  • Thinnest posterior to rectus muscle insertions
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21
Q

What type of collegen makes up the sclera

A

Contains mainly type 1 and 3 collagen

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22
Q

What ratio of the globe is formed by the sclera vs cornea

A

Sclera forms 5/6ths of the outer layer of the globe.

The cornea forms the remainder

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23
Q

What separates the sclera from the uvea

A

The suprachoroidal space

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24
Q

Innervation to the sclera

A

Innervated by long and short ciliary nerves

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25
Q

Anatomy of the Episclera

A

Heavily vascularised
The episclera is in between the sclera and the conjunctiva

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26
Q

Clinically differentiating Scleritis vs Episcleritis using phenylephrine

A

Scleritis results in inflammation of the deep vascular plexus of the sclera. This is too deep to be affected by topical phenylephrine (vasoconstrictor).

Contrastingly, episcleritis leads to the inflammation of the superficial vascular plexus and is affected by topical phenylephrine.

This means that the reddened vessels in episcleritis blanch with the administration of topical phenylephrine, compared to in scleritis where they don’t.

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27
Q

Compare scleritis vs episcleritis

A

Episcleritis is benign and self-limiting, compared to scleritis, which can be severe and sight-threatening.

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28
Q

Episcleritis

A

A benign inflammatory condition which typically re-occurs but is often self-limiting.

29
Q

Pathology of Episcleritis

A
  • Not classically associated with systemic disease
  • Inflammation of the episclera is relatively benign
30
Q

Presentation of episcleritis

A
  • Sudden onset eye ache, tearing and photophobia.
  • The eye is sectorally red and non-tender
31
Q

Investigation for episcleritis

A

The red parts of the eye blanch with the administration of topical vasoconstrictors such as phenylephrine 10%

32
Q
A

Sectoral red-eye in a patient with episcleritis

33
Q

Management of episcleritis

A

Conservative management with topical lubricants and NSAIDs for symptom control is sufficient.

Episcleritis typically self-resolves within 2 weeks

34
Q

Scleritis

A

Scleritis is uncommon and potentially blinding. It is typically classified as anterior or posterior scleritis, depending on which part of the sclera is affected. Unlike episcleritis, scleritis is often associated with systemic diseases.

35
Q

Most common type of scleritis

A

There are a few different classifications of scleritis, based on location, nodularity, necrosis and inflammation.

Anterior diffuse scleritis is the most common type.

36
Q

Most common systemic association with scleritis

A

Rheumatoid arthritis

37
Q

Presentation of scleritis

A
  • Severe deep boring eye pain that keeps the patient awake
  • Tender globe
  • Diffusely red eye
38
Q

Investigation for scleritis

A

Red-eye does not blanch with topical administration of phenylephrine

39
Q

Management of scleritis

A

Strength of treatment is determined by clinical severity.

  1. Oral NSAIDs
  2. Oral steroids
  3. IV steroids

General approach is based on initial high dose rescue therapy followed by tapering treatment.

40
Q

Uveitis

A

The term uveitis describes the inflammation of the uveal tract, involving or not involving its neighbouring ocular structures such as the retina and vitreous.

Can be caused by a wide array of diseases

41
Q

Classification of uveitis

A
  1. Anterior uveitis - Iritis + AC inflammation
  2. Intermediate uveitis - Pars planitis + vitritis
  3. Posterior uveitis - Chorioretinitis
  4. Pan uveitis - iritis + pars planitis + chorioretinitis (+ inflammation of associated structures)
42
Q
A

A patient with anterior uveitis.

43
Q

Anterior Uveitis

A
  • Anterior uveitis is the inflammation of the iris (including pars plicata)
  • Most commonly idiopathic, but can be HLA-B27 associated, infectious or systemic
  • Anterior uveitis can predispose to posterior synechiae and angle-closure
44
Q

What are keratic precipitates in anterior uveitis

A

White blood cells can accumulate in the corneal endothelium and are known as keratic precipitates (KPs).

The nature of these can be further classified based on appearance:
* Mutton fat KPs indicate granulomatous inflammation
* Stellate KPs indicate non-granulomatous inflammation

45
Q

Presentation of anterior uveitis

A
  • Inflammation of the iris and anterior ciliary body leads to AC flare.
  • Inflammation of the iris sphincter can lead to irregular meiosis.
  • Typically presents with a painful red-eye, AC flare, photophobia and blurred vision
46
Q

Intermediate Uveitis

A
  • Intermediate uveitis is the inflammation of the posterior ciliary body (pars planitis) and can also involve the vitreous
  • Inflammatory accumulations in the vitreous are described as snowballs
  • Characteristic white inflammatory exudation on the pars plana and ora Serrata is described as snow-banking (can be seen on indirect ophthalmoscopy with scleral depression)
47
Q

Presentation of Intermediate Uveitis

A
  • Painless blurry vision and floaters, without red-eye
  • Pars planitis and vitritis leads to floaters and blurring of vision.
48
Q

Causes of Infective Uveitis

A
49
Q

Important cause of childhood leukocoria

A

Toxocariasis

50
Q

How can toxocariasis be differentied from retinoblastoma?

A

Both present with leukocoria in childhood

The absence of calcification on CT scan differentiates it from retinoblastoma

51
Q

Sarcoidosis

A

A multisystem inflammatory granulomatous disorder characterised by noncaseating granulomata

52
Q

Presentation of sarcoidosis

A
  • Bilateral: hilar lymphadenopathy, CN7 palsy and parotid enlargement
  • More common in black women
  • Can cause any type of uveitis.
  • Pre-retinal granuloma (Lander sign)
53
Q

Investigation of sarcoidosis

A

Associated bloods: high ACE and hypercalcemia

54
Q

Tuberculosis

A

Multisystem Infective granulomatous disease caused by Mycobacterium tuberculosis

55
Q

Tuberculosis presentation

A
  • Can cause any type of uveitis
  • More common in Indians
  • Night sweats, weight-loss, hemoptysis and dacryoadenitis
56
Q

Investigation for TB

A

Mantoux and antigen tests

57
Q

Reactive arthritis

A
  • HLA-B27 associated reaction caused by non-gonococcal infections, most typically chlamydia.
  • A triad of: conjunctivitis, urethritis and arthritis
  • Keratoderma blennorrhagica
58
Q

Behcet’s Disease

A

HLA-B51 associated multisystem vasculitis
Anterior uveitis with a characteristic mobile hypopyon

59
Q

Investigation for Bechcet’s disease

A
  • Positive skin pathergy test (lots of skin lesions erupt in response to minor traumatic insult)
  • Pulmonary artery aneurysm is pathognomonic
60
Q

Kawasaki Disease

A

A medium vessel vasculitis of childhood

61
Q

Kawasaki Disease presentation

A
  • Bilateral anterior uveitis and conjunctivitis
  • Characteristic >5day fever which does not respond to antipyretics
  • Red palms and soles and a strawberry tongue
62
Q

Investigation for Kawasaki Disease

A

All patients require an echocardiogram to rule out coronary artery aneurysm

63
Q

Vogt-Koyanagi-Harada disease

A

Multisystem granulomatous inflammation due to melanocyte Tcell hypersensitivity (commoner people with darker skin)

  • Bilateral panuveitis
  • Prodrome of fever, meningism and tinnitus followed by vision loss and vitiligo.
  • Can effect the auditory, neurological, and dermatological systems
64
Q

Tubulointerstitial nephritis and uveitis

A

Non-granulomatous inflammation of the kidneys and the eye

  • Bilateral chronic anterior uveitis
  • Female adolescent with renal symptoms followed by ocular symptoms
65
Q

Investigation for Tubulointerstitial nephritis and uveitis

A

Elevated urinary beta-2 microglobinuria

66
Q

Juvenile Idiopathic Arthritis

A

The most common cause of anterior uveitis in children.
Also the most common rheumatological disease in children
Non-granulomatous inflammation

67
Q

Presentation of Juvenile Idiopathic Arthritis

A
  • Chronic anterior uveitis
  • Arthritis, fevers and rashes
  • Associated with cataracts and band keratopathy
68
Q

Limited Ocular Uveitis

A

Important causes of uveitis which are limited to the eye without systemic involvement

69
Q

HLA associations with various ophthalmic diseases

A

Duke Elder (12 decks)

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