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Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK)
Cornea
1. Clinical Analogy & Historical Evolution
Exam pearl
- Clinical Analogy - The Windshield Metaphor: Think of the cornea as a car windshield. In Fuchs endothelial dystrophy or pseudophakic bullous keratopathy, it is only the inner glass (endothelium + Descemet membrane) that is scratched or fogged - the outer windshield glass (epithelium, stroma) is optically intact. DSAEK replaces only the inner layer with a precision-cut donor disc, instead of replacing the entire windshield (as in penetrating keratoplasty). This selective replacement is the revolution of posterior lamellar keratoplasty.
Historical Timeline
PEARL
- Descemet’s stripping automated endothelial keratoplasty (DSAEK) uses an automated microkeratome (hence “A” in Descemet’s stripping automated endothelial keratoplasty [DSAEK]) to create reproducible donor discs.
- Descemet’s stripping endothelial keratoplasty (DSEK) uses manual dissection.
Nomenclature - What Exactly Is Descemet Stripping Automated Endothelial Keratoplasty (DSAEK)?
| Term | Full Form | Key Feature |
|---|---|---|
| Descemet Stripping Endothelial Keratoplasty (DSEK) | Descemet Stripping Endothelial Keratoplasty (DSEK) | • Manual posterior dissection |
| Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) | Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) | • Microkeratome-cut donor disc |
| Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) | Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) | • Donor stroma ≤100 µm |
| Nano-Thin Descemet Stripping Automated Endothelial Keratoplasty (NT-DSAEK) | Nano-Thin Descemet Stripping Automated Endothelial Keratoplasty (NT-DSAEK) | • Donor stroma ≤50 µm |
| Femtosecond-Assisted Descemet Stripping Automated Endothelial Keratoplasty (Femto-DSAEK) | Femtosecond-Assisted Descemet Stripping Automated Endothelial Keratoplasty (Femto-DSAEK) | • Femtosecond laser dissection |
| Descemet Membrane Endothelial Keratoplasty (DMEK) | Descemet Membrane Endothelial Keratoplasty (DMEK) | • Descemet membrane and endothelium only (no stroma) |
| Pre-Descemet Endothelial Keratoplasty (PDEK) | Pre-Descemet Endothelial Keratoplasty (PDEK) | • Descemet membrane, pre-Descemet layer, and endothelium |
| Term | Full Form | Key Feature |
|---|---|---|
| Descemet Stripping Endothelial Keratoplasty (DSEK) | Descemet Stripping Endothelial Keratoplasty (DSEK) | • Manual posterior dissection |
| Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) | Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) | • Microkeratome-cut donor disc |
| Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) | Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) | • Donor stroma ≤100 µm |
| Nano-Thin Descemet Stripping Automated Endothelial Keratoplasty (NT-DSAEK) | Nano-Thin Descemet Stripping Automated Endothelial Keratoplasty (NT-DSAEK) | • Donor stroma ≤50 µm |
| Femtosecond-Assisted Descemet Stripping Automated Endothelial Keratoplasty (Femto-DSAEK) | Femtosecond-Assisted Descemet Stripping Automated Endothelial Keratoplasty (Femto-DSAEK) | • Femtosecond laser dissection |
| Descemet Membrane Endothelial Keratoplasty (DMEK) | Descemet Membrane Endothelial Keratoplasty (DMEK) | • Descemet membrane and endothelium only (no stroma) |
| Pre-Descemet Endothelial Keratoplasty (PDEK) | Pre-Descemet Endothelial Keratoplasty (PDEK) | • Descemet membrane, pre-Descemet layer, and endothelium |
2. Anatomy & Pathophysiology Relevant to DSAEK
Corneal Layers - Surgical Anatomy
| Layer | Thickness | Role | Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) Relevance |
|---|---|---|---|
| Epithelium (5–6 layers) | • 50–60 µm | • Barrier • Regenerates | • Not disrupted in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Bowman layer | • 8–12 µm | • No regeneration | • Not disrupted in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Stroma (90% of cornea) | • ~500 µm | • Structural scaffold | • Retained in recipient • Donor carries a thin posterior stromal lamella in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Dua/Pre-Descemet layer | • ~10 µm (range 6–16 µm) | • Almost acellular • Predominantly type I and some type VI collagen with abundant elastin | • Relevant in pre-Descemet endothelial keratoplasty (PDEK) |
| Descemet membrane | • Thickness increases with age • Approximately 3 µm at birth and >10 µm in elderly corneas | • Basement membrane of the endothelium • Includes an anterior banded zone and posterior non-banded zone | • Stripped from recipient • Present in the donor disc with donor endothelium and posterior stromal lamella in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Endothelium | • ~5 µm • ~2,000–2,500 cells/mm² | • Single layer • Active pump | • PRIMARY target of Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) • Replaced with healthy donor cells |
| Layer | Thickness | Role | Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) Relevance |
|---|---|---|---|
| Epithelium (5–6 layers) | • 50–60 µm | • Barrier • Regenerates | • Not disrupted in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Bowman layer | • 8–12 µm | • No regeneration | • Not disrupted in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Stroma (90% of cornea) | • ~500 µm | • Structural scaffold | • Retained in recipient • Donor carries a thin posterior stromal lamella in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Dua/Pre-Descemet layer | • ~10 µm (range 6–16 µm) | • Almost acellular • Predominantly type I and some type VI collagen with abundant elastin | • Relevant in pre-Descemet endothelial keratoplasty (PDEK) |
| Descemet membrane | • Thickness increases with age • Approximately 3 µm at birth and >10 µm in elderly corneas | • Basement membrane of the endothelium • Includes an anterior banded zone and posterior non-banded zone | • Stripped from recipient • Present in the donor disc with donor endothelium and posterior stromal lamella in Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) |
| Endothelium | • ~5 µm • ~2,000–2,500 cells/mm² | • Single layer • Active pump | • PRIMARY target of Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) • Replaced with healthy donor cells |
Normal endothelial cell density (ECD): 2,500–3,000 cells/mm² in young adults; declines physiologically ~0.5% per year.
| Endothelial cell density (ECD) (cells/mm²) | Clinical Implication |
|---|---|
| >2000 | • Normal endothelial cell density; corneal status depends on the full clinical assessment. |
| 1000–2000 | • Below the normal physiological condition; interpret with clinical findings and surgical risk factors. |
| 500–1000 | • Corneal transparency is endangered; even slight endothelial damage may induce bullous keratopathy. |
| <500 | • Marked endothelial compromise; corneal edema may be absent, so assess corneal clarity and edema clinically. |
| <300 | • Very low endothelial cell density; assess for corneal edema and manage according to clinical findings. |
| Endothelial cell density (ECD) (cells/mm²) | Clinical Implication |
|---|---|
| >2000 | • Normal endothelial cell density; corneal status depends on the full clinical assessment. |
| 1000–2000 | • Below the normal physiological condition; interpret with clinical findings and surgical risk factors. |
| 500–1000 | • Corneal transparency is endangered; even slight endothelial damage may induce bullous keratopathy. |
| <500 | • Marked endothelial compromise; corneal edema may be absent, so assess corneal clarity and edema clinically. |
| <300 | • Very low endothelial cell density; assess for corneal edema and manage according to clinical findings. |
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Keep reading Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK)
23 more sections are included with the Clinical plan.
- Endothelial Pump Mechanism
- Pathophysiology of Common DSAEK Indications
- Indications & Contraindications
- Absolute Contraindications
- Relative Contraindications / Challenging Scenarios
- Donor Tissue Preparation