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Corneal & External Eye Disease

Audit and Research

The number of corneal transplant surgeries performed, success rates, diagnoses made and a comparison of success rates and survival rates, between procedures (PK versus ALK versus EK), are shown in Figures 3.1 to 3.4.

Penetrating Keratoplasty (PK) is a form of microsurgery in which the central portion of the damaged or cloudy cornea is removed completely, and a clear and healthy donor cornea is sutured in its place with very fine microsurgical nylon sutures. However, lamellar surgery such as Endothelial Keratoplasty (EK) and Anterior Lamellar Keratoplasty (ALK) have become the methods of choice for many cornea diseases.

In EK, the diseased endothelial cells, present on the innermost layer of the cornea, are replaced through a small keyhole incision with techniques such as DSAEK and DMEK. In ALK, diseased outer layers of the cornea are removed and replaced, while preserving the remaining healthy corneal layers. These techniques result in stronger and more stable corneas, and lower graft rejection and graft failure rates compared to PK surgery.

The Singapore Cornea Transplant Study at SNEC demonstrate the superior long-term graft survival of lamellar keratoplasty compared to PK. ALK was associated with the highest cumulative probability of survival in the medium term, followed by EK, and finally PK.

Benchmarks of success

TABLE 3.1. Comparison of SNEC audit data with other corneal graft registries/studies


Name of corneal graft registry/study

Graft survival (%)


SNEC audit data

92/67 (1-year/5-year)

Australian Corneal Graft Registry (Williams et al., 2015)

94/68 (1-year/6-year)

Cornea Donor Study (USA)

(Cornea Donor Study Investigator Group, 2008)

97/86 (1-year/5-year)

United Kingdom Transplant Database

(Kasbekar, Jones, Ahmad, Larkin, & Kaye, 2014)

92 (5-year)


SNEC audit data

96/94/91 (1-year/3-year/5-year)

Australian Corneal Graft Registry (Williams et al., 2015)

93/87 (1-year/3-year)

United Kingdom Transplant Database

(Kasbekar et al., 2014)

90 (5-year)


(All diagnoses)

Singapore Corneal Transplant Study

(Ang, Soh, Htoon, Mehta & Tan, 2016)

79.4 (5-year)


(Fuchs' dystrophy)

Singapore Corneal Transplant Study (Ang et al., 2012)

93 (3-year)

Australian Corneal Graft Registry (Williams et al., 2015)

96 (3-year)


  1. Ang, M., Mehta, J, S., Lim, F., Bose, S., Htoon, H.M., & Tan, D. (2012). Endothelial cell loss and graft survival after Descemet’s stripping automated endothelial keratoplasty and penetrating keratoplasty. Ophthalmology, 119, 2239-2244.

  2. Ang, N., Soh, Y., Htoon, H. M., Mehta, J. S., & Tan, D. (2016). Five-year graft survival comparing Descemet stripping automated endothelial keratoplasty and penetrating keratoplasty. Ophthalmology, 123, 1646-1652.

  3. Cornea Donor Study Investigator Group. (2008). The effect of donor age on corneal transplantation outcome results of the cornea donor study. Ophthalmology, 115, 620-626.

  4. Kasbekar, S. A., Jones, M. N., Ahmad, S., Larkin, D. F., & Kaye, S. B. (2014). Corneal transplant surgery for keratoconus and the effect of surgeon experience on deep anterior lamellar keratoplasty outcomes. American Journal of Ophthalmology, 158, 1239-1246.

  5. Khor, W. B., Han, S. B., Mehta, J. S., & Tan, D. T. (2013). Descemet stripping automated endothelial keratoplasty with a donor insertion device: clinical results and complications in 100 eyes. American Journal of Ophthalmology, 156, 773-779.

  6. Mehta, J. S., Por, Y. M., Poh, R., Beuerman, R. W., & Tan, D. (2008). Comparison of donor insertion techniques for descemet stripping automated endothelial keratoplasty. Archives of Ophthalmology, 126, 1383-1388.

  7. Tan, D. T., Tay, A. B., Theng, J. T., Lye, K. W., Parthasarathy, A., Por, Y. M., Liu, C. (2008). Keratoprosthesis surgery for end-stage corneal blindness in Asian eyes. Ophthalmology, 115, 503-510.

  8. Williams, K. A., Keane, M, C., Galettis, R. A., Jones, V. J., Mills, R. A., & Coster, D. J. (2015). The Australian Corneal Graft Registry 2015 Report. Retrieved from


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