Fig. 13.1
Endothelial keratoplasty after failed penetrating keratoplasty – graft survival. Median survival time was 57 months (interquartile range, 36–70.8 months). The region in grey represents the 95 % confidence interval for the probability estimate with vertical inflexions indicating censored data (Reproduced with permission from Mitry et al. [5])
Table 13.1
Hazard ratios and associated confidence intervals for pre- and postoperative risk factors for DSAEK failure after PK
Pre- and postoperative risk factors for DSAEK failure | ||
|---|---|---|
p-value | ||
Age | ||
≥80 years | 1 | |
60–79 years | 2.38(0.89–6.30) | 0.082 |
40–59 years | 3.98(1.40–11.37) | 0.010 |
<39 years | 8.42(2.23–31.69) | 0.002 |
Centre | ||
1 | 1 | |
2 | 0.15(0.06–0.39) | <0.001 |
3 | 0.57(0.14–2.26) | 0.43 |
4 | 0.11(0.03–0.37) | <0.001 |
5 | 0.16(0.06–0.40) | <0.001 |
6 | 0.54(0.16–1.85) | 0.32 |
Previous glaucoma surgery | ||
None | 1 | |
Trabeculectomy | 2.12(0.78–5.75) | 0.14 |
Shunt drainage | 4.12(1.63–10.41) | 0.003 |
Rejection episodes prior to PK failure | ||
No episodes | 1 | |
Rejection episodes | 2.41(1.02–5.70) | 0.04 |
Post-DSAEK rejection | ||
No | 1 | |
Yes | 2.49(1.18–5.26) | 0.01 |
5-year survival for EK after PK is approximately 50 % (similar to PK after PK).
Visual outcomes in EK after PK are similar to those for PK after PK.
Preoperative predictors of graft failure in EK after PK were young age, previous glaucoma tube surgery, and endothelial rejection prior to PK failure.
Rejection prior to PK failure increases the risk of rejection in EK after PK, and rejection in the EK increases the risk of graft failure.
Surgery in high-volume, single surgeon centres had a protective effect.
Transplant registries are yet to report on the outcomes of EK after PK. Even when these data do emerge, as illustrated by the centre effect above, it may initially be difficult to tease out the learning curve from the true clinical potential for new EK techniques. At this stage, it is probably safe to conclude that the advantages of early visual rehabilitation and closed eye surgery (relative safety under local anaesthetic) are a rational basis for choosing EK after PK in suitable cases of failed primary PK for Fuchs dystrophy, but final visual results and graft survival have not yet been shown to be superior.
Outcome data reported to date are results for Descemet stripping automated EK (DSAEK) rather than Descemet membrane endothelial keratoplasty (DMEK). Since techniques for graft preparation and implantation in DMEK have become better understood in the last 5 years, many EK surgeons have switched to DMEK [7]. Potential advantages for DMEK in the context of EK after PK are reduced rejection risk [8, 9] and reduced graft detachment in association with an irregular posterior corneal contour.
13.3 Rejection Prophylaxis
In primary transplantation for Fuchs dystrophy, 2-year rejection probabilities for PK and DSAEK appear to be similar at approximately 10–20 %. Rates are an order of magnitude lower (1–2 %) for DMEK [8, 9]. It is not yet clear whether this reduced rejection risk translates to DMEK after failed PK, but it would be surprising if a tenfold reduction in rejection risk only applied to primary transplantation. Inflammation at the time of transplantation is an important risk factor for rejection and subsequent graft failure. Pretreatment with topical steroids to minimize any residual inflammation in cases of transplant failure secondary to endothelial rejection is therefore a logical step.
The role of tissue matching in keratoplasty remains poorly defined, and any benefits for matching strategies in high-risk PK may not apply to DMEK [10]. Similarly, although systemic immunosuppression is widely used with the aim of reducing the risk of transplant rejection in high-risk PK cases, particularly those with multiple failed grafts, the evidence base supporting this additional intervention remains weak [11]. As with the protective effect observed for DMEK in primary transplantation, it is not clear whether benefits observed in some high-risk PK series will translate to DMEK after PK, and all systemic immunosuppressive drugs have a significant side-effect profile. Another factor to consider in DMEK after PK before exposing patients to potentially hazardous drug treatment is the relative ease of repeat surgery. DMEK can be performed through a 2.4-mm self-sealing incision under local anaesthetic, and the risks to the eye from repeat surgery are relatively well contained.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
