Changes to collagen that can lead to “corneal leukoma” or corneal scarring:1
- Type
- Size
- Distribution
- Inflammation
- Spatial organization due to infection
- Any other cause of opacity and irregularities
Layers of the Cornea
1) Epithelium
- Barrier to microbes, chemicals, and water
2) Bowman’s layer
- Maintains corneal shape
3) Stroma
- Mechanical Strength
- Transparency
4) Descemet’s membrane
- Basement membrane anterior to endothelial cells
5) Endothelium
- Responsible for the transparency of the cornea by regulating the stromal water content (“water pumps”)2
Causes of corneal scarring
- Severe dry eye
- Injury or trauma (idiopathic, chemical, and surgical)
- Infections
- Diseases of the cornea or eye surfaces, such as keratoconus
Symptoms of corneal scarring
For example: keratoconus is usually a bilateral disease, however if there are complications caused by corneal scarring, patients may present with asymmetric symptoms such as one eye may be much more severely blurred than the other.4
Diagnosis of corneal scarring
Treatment options
Full thickness keratoplasty was the most common corneal transplantation technique over the last few decades, however, the popularity of selective lamellar transplantations of the affected layers of the cornea is increasing.
Common types of corneal transplantations:
Name | Technique | Indication | Complications |
---|---|---|---|
Penetrating Keratoplasty (PKP) | Removal of all layers of the host cornea with full thickness transplantation of the donor graft. | Full-thickness scar, bullous keratopathy, keratoconus, graft failure. | Graft rejection, graft failure, hemorrhage, infection, astigmatism, suture complications. |
Deep Anterior Lamellar Keratoplasty (DALK) | Diseased host epithelium and stroma removed. Transplant of donor cornea epithelium, Bowman’s membrane, and corneal stroma. | Keratoconus, stromal scar, hereditary stromal dystrophies. | Graft rejection, intraoperative Descemet membrane tear, astigmatism. |
Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) | Both endothelium and Descemet membrane are removed and replaced with the donor endothelium, Descemet membrane and stroma. | Fuchs’ dystrophy, bullous keratopathy, graft failure. | Graft detachment, graft failure, graft rejection. |
Descemet membrane endothelial keratoplasty (DMEK) | Both endothelium and Descemet membrane are removed and replaced with the donor endothelium and Descemet membrane. | Fuchs’ dystrophy, bullous keratopathy, graft failure. | Graft detachment, graft failure.8,9 |
Visual rehabilitation
“The goal of low vision rehabilitation is to train patients in strategies of coping with the diminished vision. Maintaining independence and improving the quality of life are the main objectives.”
Conclusion
References
- DelMonte DW, Kim T. Anatomy and physiology of the cornea. J Cataract Refract Surg. 2011;37(3):588-598. doi:10.1016/j.jcrs.2010.12.037
- Eghrari AO, Riazuddin SA, Gottsch JD. Overview of the Cornea: Structure, Function, and Development. Prog Mol Biol Transl Sci. 2015;134:7-23. doi:10.1016/bs.pmbts.2015.04.001
- Ahmed F, House RJ, Feldman BH. Corneal Abrasions and Corneal Foreign Bodies. Prim Care. 2015;42(3):363-375. doi:10.1016/j.pop.2015.05.004
- Bae SS, Chan CC. Superficial keratectomy: indications and outcomes. Can J Ophthalmol. 2018 Dec;53(6):553-559. doi: 10.1016/j.jcjo.2018.01.030. Epub 2018 Apr 4. PMID: 30502977.
- Singh R, Gupta N, Vanathi M, Tandon R. Corneal transplantation in the modern era. Indian J Med Res. 2019 Jul;150(1):7-22. doi: 10.4103/ijmr.IJMR_141_19. PMID: 31571625; PMCID: PMC6798607.
- Abdelaal AM, Alqassimi AH, Malak M, Hijazi HT, Hadrawi M, Khan MA. Indications of Keratoplasty and Outcomes of Deep Anterior Lamellar Keratoplasty Compared to Penetrating Keratoplasty. Cureus. 2021 Mar 11;13(3):e13825. doi: 10.7759/cureus.13825. PMID: 33859889; PMCID: PMC8040744.
- Liu S, Wong YL, Walkden A. Current Perspectives on Corneal Transplantation. Clin Ophthalmol. 2022 Mar 4;16:631-646. doi: 10.2147/OPTH.S289359. PMID: 35282172; PMCID: PMC8904759.
- Le R, Yucel N, Khattak S, Yucel YH, Prud'homme GJ, Gupta N. Current indications and surgical approaches to corneal transplants at the University of Toronto: A clinical-pathological study. Can J Ophthalmol. 2017 Feb;52(1):74-79. doi: 10.1016/j.jcjo.2016.07.005. Epub 2016 Sep 7. PMID: 28237153.
- Boynton GE, Woodward MA. Evolving Techniques in Corneal Transplantation. Curr Surg Rep. 2015 Feb 1;3(2):html. doi: 10.1007/s40137-014-0079-5. PMID: 26101726; PMCID: PMC4474142.
- Vision rehabilitation. AOA. https://www.aoa.org/practice/specialties/vision-rehabilitation?sso=y. Accessed July 19, 2022.
- E.P. Herlihy, P.N. Youssef, M.V. Netto, T.T. Shen; Management of a Severe Corneal Scar Using Lamellar Keratoplasty With a Standard Hansatome Microkeratome and a Frozen Globe . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4380.