Ophthalmology · MU Sofia

10. Applied anatomy of the uvea

Covers the uvea as the eye's vascular middle layer and its functions: nutrition and gas exchange, accommodation, light regulation and intraocular pressure. It then goes through the iris, its four microscopic layers and the muscles controlling the pupil, followed by the ciliary body with its five layers and ciliary processes, and the choroid with its layers. It closes with the three arterial supplies to the uveal tract and its venous drainage into the ophthalmic veins and cavernous sinus.

Inside: 4 sections · 6 labelled pictures · 12 flashcards · 5 min

Topic 10 of 91 in the MU Sofia syllabus for Ophthalmology (Medicine, Year 4). The free AceMed note covers it in 4 sections, about 670 words (5 min of reading), with 12 flashcards.

In this note

  1. Anatomy of the Uvea
  2. Topic 6
  3. Ciliary body
  4. Choroid

Topic 6

= UVEA (ciliary bodies + iris + choroid) → Intermediate layer of the eye

=> vascular layer and the following important functions:

1. Nutrition/ gas exchange.

Directly perfuse→ ciliary body +iris

Indirectly by diffusion →outer retina, sclera & lens/cornea by aqueous humour formed by ciliary bodies

2.Accommodation (=adjusting optical power in order to focus image on retina) by the ciliary body contraction/relaxation → changing shape of lens

3.Light regulation → (retinal illumination) by the iris's control over the pupil

4. Intraocular pressure→ via contractions of muscles pulling on sclera meshwork

IRIS

→ colored disc in the eye visible through the clear cornea. ; mainly connective tissue + smooth ms. It is situated between the cornea and the crystalline lens.

It is the anterior most part of the Uveal tract; thin and circular At its periphery it attaches to the middle of the anterior ciliary surface It forms the anterior chamber anteriorly (with cornea) and posterior Chamber posteriorly (with ciliary processes)

Microscopically consist of 4 Layers

  1. 1. Anterior limiting layer
  2. 2.Iris stroma
  3. 3.Anterior epithelial layer
  4. 4.Posterior epithelial layer

1. Anterior limiting layer (endothelial )

Anterior most part ,consisting of melanocytes and fibroblasts The crypts lack this layer and the colour of the iris depends on this layer In Blue→ it is thin and contains little pigment in Brown the opposite

2.Iris stroma

Loose collagenous network encompassing the sphincter pupillae muscle Dilator pupillae muscle, vessels, nerves pigment and immune cells The sphincter muscles are (para, III)circular band of muscle in the Pupillary part of iris which constrict the pupil. The dilator muscle lies in the posterior part of the ciliary zone supplied by Cervical sympathetic nerves and dilates the pupil

3.Anterior epithelial layer

Continuation of the pigmented epithelium of retina &ciliary body and from this dilator muscles arises

4. Posterior pigmented epithelial layers

-Continuation of the non-pigmented epithelial layer of the ciliary body At pupillary margin it merges with the anterior pigmented epithelium

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