Reconstructing the ocular surface
KPro can achieve good outcomes where standard keratoplasty is not appropriate
Sadeer B Hannush MD
Although not traditionally considered a first-line surgical option for ocular surface reconstruction, keratoprosthesis (KPro) devices have the ability to achieve good visual outcomes in patients who are poor candidates for standard keratoplasty surgery, according to Sadeer B Hannush MD.
“Historically, permanent keratoprosthesis surgery has been offered only after multiple graft failures. However, in the setting of ocular surface disease that is not amenable to conventional reconstructive surgical modalities, permanent KPro may be considered as a primary surgical intervention for the purpose of visual rehabilitation,” he said at the World Ophthalmology Congress 2020 Virtual.
The Boston KPro is currently the most frequently used keratoprosthesis, consisting of a back plate and optical stem that are incorporated with a donor cornea at the time of surgery. In trying to decide whether to offer a full-thickness graft or a KPro device, some considerations need to be borne in mind, said Dr Hannush, Wills Eye Hospital, Philadelphia, Pennsylvania, United States.
“We need to weigh the likelihood of subsequent graft survival with a graft versus KPro implantation, and also take on board issues such as visual rehabilitation, systemic immunosuppression and the age of the patient in making our decision,” he said.
Once the surgeon has decided to proceed with a KPro, there are further strategic choices to be made in terms of leaving the patient aphakic or pseudophakic, and selecting the type and size of posterior plate to be used.
“Glaucoma management is the Achilles’ heel of KPro surgeries, so we need to plan in advance if we are placing a glaucoma drainage device or planning endoscopic cyclophotocoagulation (ECP) or other options combined with the KPro device,” he said
Dr Hannush illustrated the utility of the KPro in two case studies. The first patient was a 75-year-old male who had multiple failed full thickness and endothelial grafts in his only seeing eye. B-scan ultrasonography, however, showed a normal posterior segment, so the decision was taken to proceed with KPro surgery. After removing the previous failed grafts, the 8.5mm KPro with a titanium back plate embedded in a full thickness cornea graft was sutured in place. The final outcome was good, with the patient achieving 20/50 vision several days after surgery, said Dr Hannush.
The second case study highlighted by Dr Hannush was a 40-year-old female patient with congenital aniridia.
“The ocular surface was very irregular and vascularised with limbal stem cell deficiency, and the patient also had a cataract, so it was quite challenging,” he said.
After performing a partial vitrectomy, Dr Hannush successfully removed the cataract and implanted a threepiece IOL into the capsular bag prior to suturing the KPro device/corneal transplant complex into place.
“The patient achieved a good outcome and was very happy with her vision after the surgery,” he concluded.