Eyeball Anatomy
👁️ Eyeball Anatomy Overview
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Shape: Spherical (approx. 24 mm diameter)
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Weight: ~7.5 grams
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Located in: Bony orbit
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Covered by: Conjunctiva (anteriorly)
The eyeball consists of 3 layers (tunics) and is filled with three chambers containing fluids for shape and function.
🧱 Layers of the Eyeball
1️⃣ Fibrous Layer (Outer)
Provides shape and protection
| Part | Function |
|---|---|
| Cornea | Transparent, avascular; refracts light into the eye |
| Sclera | Opaque white; attachment for extraocular muscles |
➡️ Cornea + sclera meet at the limbus
2️⃣ Vascular Layer (Uvea / Middle)
Provides blood supply and controls light entry
| Part | Function |
|---|---|
| Iris | Pigmented diaphragm with pupil in the center; regulates light |
| Ciliary body | Contains ciliary muscle (lens accommodation) and ciliary processes (aqueous humor production) |
| Choroid | Richly vascularized; nourishes outer retina |
3️⃣ Neural Layer (Inner)
Processes visual information
| Part | Function |
|---|---|
| Retina | Contains photoreceptors (rods & cones) |
| Optic disc | Where optic nerve exits; blind spot |
| Macula lutea / Fovea centralis | Sharpest central vision |
🧪 Internal Chambers & Contents
🔹 Anterior Chamber
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Between cornea and iris
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Filled with aqueous humor
🔹 Posterior Chamber
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Between iris and lens
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Also contains aqueous humor
🔹 Vitreous Chamber
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Behind the lens, filled with vitreous humor
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Gel-like, maintains globe shape and retinal attachment
🔍 Other Key Structures
| Structure | Role |
|---|---|
| Lens | Biconvex, transparent; focuses light onto retina |
| Zonular fibers | Suspend the lens, connect it to the ciliary body |
| Aqueous humor | Nourishes cornea and lens, maintains IOP |
| Vitreous humor | Supports shape, transmits light, holds retina in place |
| Pupil | Central opening of the iris, controls light entry |
| Ora serrata | Junction between retina and ciliary body (retina ends here) |
📊 Summary Table of the 3 Layers:
| Layer | Components | Function |
|---|---|---|
| Fibrous | Cornea, Sclera | Protection, light refraction |
| Vascular | Iris, Ciliary body, Choroid | Blood supply, light control |
| Neural | Retina, Optic nerve | Image formation and transmission |
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