Free previewYou're reading the free part of this topic. The rest is included with Clinical.See what's included
Anatomy of the Sclera
Anatomy
Teaching images
81. Opening Clinical Analogy
Teaching image
1Clinical Analogy
- Think of the sclera as the shell of a hard-boiled egg.
- The outer fibrous coat (sclera) gives the globe its rigid spherical shape just as the eggshell maintains the egg's form - firm enough to resist deformation yet slightly elastic to absorb intraocular pressure (IOP) fluctuations.
- Where the shell is thinnest (behind the equator, just posterior to the rectus insertions) it is most susceptible to rupture with blunt trauma - your classic 'eggshell fracture at the thinnest point.'
2. Gross Anatomy & Dimensions
Teaching image
1The sclera is the opaque, fibrous, outermost coat of the eyeball forming ~5/6ths of its surface area. The cornea forms the anterior 1/6th. Together they constitute the outer fibrous tunic.
| Parameter | Value / Detail |
|---|---|
| Total surface area | • ~16.3 cm² |
| Thickness - at limbus | • ~0.5–0.8 mm (measurement-dependent) |
| Thickness - posterior to rectus insertions | • ~0.3 mm (thinnest point) |
| Thickness - equator | • ~0.4–0.5 mm |
| Thickness - posterior pole | • ~0.9–1.0 mm (around optic nerve) |
| Outer colour | • White (adults) • translucent bluish (infants, thin in myopia) |
| Inner surface | • Brown (lamina fusca) due to uveal pigment |
| Radius of curvature | • ~11–12 mm externally |
| Tensile strength | • High - withstands pressures >600 mmHg acutely |
| Parameter | Value / Detail |
|---|---|
| Total surface area | • ~16.3 cm² |
| Thickness - at limbus | • ~0.5–0.8 mm (measurement-dependent) |
| Thickness - posterior to rectus insertions | • ~0.3 mm (thinnest point) |
| Thickness - equator | • ~0.4–0.5 mm |
| Thickness - posterior pole | • ~0.9–1.0 mm (around optic nerve) |
| Outer colour | • White (adults) • translucent bluish (infants, thin in myopia) |
| Inner surface | • Brown (lamina fusca) due to uveal pigment |
| Radius of curvature | • ~11–12 mm externally |
| Tensile strength | • High - withstands pressures >600 mmHg acutely |
Exam Pearl
- The thinnest scleral point (~0.3 mm) lies just posterior to the rectus muscle insertions - the classic site of occult globe rupture with blunt trauma, even when the anterior segment appears intact.
Free preview ends here
Keep reading Anatomy of the Sclera
16 more sections are included with the Clinical plan.
- HISTOLOGICAL LAYERS (Outer → Inner)
- Scleral Openings & Channels
- The Limbus - Surgical Watershed Zone
- Blood Supply of the Sclera
- Nerve Supply of the Sclera
- Scleral Spur - Gonioscopic & Surgical Landmark