Table 2.
Types of surgical procedures, indications, advantages and disadvantages, according to the studies cited.
| Procedure | Indications | Advantages | Disadvantages |
|---|---|---|---|
| Contact lens fitting | First line treatment | Non-invasive, better visual acuity than spectacles | Corneal scarring, whorl keratopathy, corneal micro-trauma, epithelial and anterior stroma disruption, and chronic ocular inflammation |
| Compressive sutures | Early case of ectasia post-PK | Minimal risk of penetration into the anterior chamber | Improvement may be unpredictable and subject to loss of effect with time due to the tissue elasticity |
| Wedge resection | Ectasia of limited extension along the graft–host junction. | Prevent or delay the need for repeat PK, no risk of rejection or interface haze | Postoperative unstable astigmatism. |
| Intra ocular lens implantation | Correct post-PK astigmatism in phakic eyes or during cataract surgery | Does not alter corneal profile and transparency | Endothelial cell loss, chronic inflammation, cystoid macular edema, pigment dispersion, leading to pigmentary glaucoma, cilio-lenticular block, iris synechiae, sphincter erosion, and iris transillumination |
| Repeat penetrating keratoplasty | Extensive ectasia involving the graft-host junction | Visual acuity and astigmatism improve significantly after large PK as sutures are placed more peripherally and influence less the central graft | Increased risk of graft rejection, late endothelial failure, cataract development, and augmented risk of postoperative glaucoma and immunologic rejection |
| Tuck-in lamellar keratoplasty | Diffuse thinning of the peripheral cornea with advanced corneal ectasia involving corneal periphery and the graft-host interface | Tectonic support to the weakened peripheral cornea beyond the previous graft–host junction, no damage to the recipient’s limbal stem cells | Challenging technique to perform for both donor and host preparation |
| Peripheral reconstructive and annular lamellar keratoplasty | Diffuse thinning of the peripheral cornea with advanced corneal ectasia | Preserve the previous PK and restore normal peripheral corneal thickness, minimize forward protrusion of the cornea | Causes peripheral vascularization with early loosening of sutures. Surgically challenging to perform for both donor and host preparation |
| Overlay deep anterior lamellar keratoplasty | Extensive corneal ectasia. Aims to correct the donor and host cornea profile and thickness without replacing the PK endothelium | Preserve the globe integrity, the donor graft and peripheral host endothelium, thus reducing the risk of endothelial rejection, late graft failure, and complications related to open-sky surgery | Technically more challenging than conventional DALK, risk of perforation when dissecting across the host-graft junction |
PK = penetrating keratoplasty; DALK = deep anterior lamellar keratoplasty.