Effectiveness of PKP vs DSAEK in Terms of 2-year Postoperative Visual Acuity in Advanced BPK

Bullous pseudophakic keratopathy (PBK) is the development of irreversible corneal edema after cataract surgery. Since approximately 20 million people worldwide undergo cataract surgery annually, and PBK can occur in 1-2% of cataract operations, PBK remains a major indication for corneal transplantation. Indeed, it accounts for a quarter of the 5,000 corneal transplant operations that are conducted in France each year. Penetrating keratoplasty (PKP) involves transplanting a full-thickness corneal button. It was the only corneal transplant technique available for PBK until 2004-2006, when two posterior lamellar corneal transplantation methods were invented and refined, namely, Descemet stripping automated keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). Both have transformed the management of PBK and are often preferred over PKP because of faster visual improvement and fewer complications, including astigmatism and graft rejection. This is particularly true for cases where preoperative visual acuity is better than 2/10 (0.7 logMAR). However, PKP is still indicated when visual acuity is below the ability to see hand movements (2 logMAR): in such cases, the severe stromal damage requires full-thickness transplantation. However, for PBK cases with intermediate visual acuity (i.e. between 0.7 and 2 logMAR), there is doubt about the best therapeutic solution. The relatively severe corneal damage in these cases is a contraindication for DMEK, which is a much more technically challenging procedure than DSAEK. Thus, the surgeon must choose either DSAEK or PKP. DSAEK is suitable for older people who mainly complain of eye pain: it is a simple and painless procedure that leads to satisfactory outcomes in 75% of cases. However, in the remaining 25% of patients, ocular pain may persist and/or the recovery of visual acuity is too limited and the patient is dissatisfied. In such cases, the patient is indicated for regraft with PKP. Given the poor visual outcomes of DSAEK for a substantial minority of patients with preoperative visual acuity between 0.7 and 2 logMAR, the present study asks whether PKP should be the primary choice for such patients. To improve decision-making for PBK, the study also asks whether it is possible to define preoperative visual acuity and/or central corneal thickness (CCT) thresholds that signal a high risk of regraft after primary DSAEK and therefore indicate a need for primary PKP.

Inclusion criteria

• The patient:

• Is ≥ 50 years old.
• Has advanced PBK, with a best corrected visual acuity that lies between being able to see a hand move (i.e. 2 logMAR, included) and 2/10 excluded (i.e. 0.7 logMAR, excluded) and a central corneal thickness that exceeds 600 μm.
• Is indicated for a corneal transplant.
• Is pseudophakic.
• Has provided free and informed written consent.
• Is affiliated to a social security scheme.
• Can be followed-up by the same investigating team during the study period.

Exclusion criteria

• The patient:

• Has a history of corneal transplant on either eye (i.e. the study surgery will be the first corneal transplant for the patient).
• Has an anterior chamber lens implant or is aphakic.
• Has an ocular comorbidity that will impact visual acuity recovery: exudative or advanced atrophic AMD, advanced diabetic retinopathy (macular edema), advanced glaucoma (damage to the central visual field), important sequelae of central venous thrombosis of the retina or retinal detachment, previous amblyopia.
• Has a contraindication to general anesthesia.
• Is deprived of freedom, or under a legal protective measure.
• Is included in another clinical study.
• Has a severe general condition that might lead to premature discontinuation of the trial before the end of treatment period.