VISUAL REHABILITATION

While there has been tremendous progress in the field of ocular surface transplantation for eyes with limbal stem cell deficiency (LSCD) and excellent visual outcomes are being obtained using the Boston type 1 keratoprosthesis (Boston KPro, Massachusetts Eye and Ear Infirmary), visual rehabilitation of patients with bilateral corneal blindness due to LSCD still represents a challenge, said Virender S Sangwan MD, at the 26th APACRS meeting.

“Patients with bilateral LSCD can be managed using a variety of techniques,” said Dr Sangwan, Dr Paul Dubord Chair in Cornea, LV Prasad Eye Institute, Hyderabad, India. “However, there is limited literature on this topic and is no easy answer on the solution to this complex clinical problem.”

Options for rehabilitation in eyes with bilateral LSCD and a wet surface include limbal allograft techniques, autologous cultivated oral mucosal epithelial transplantation (COMET), and the Boston KPro. Dr Sangwan reviewed experiences using these procedures at his institution over the past 10 years in a series of 62 eyes of 50 patients. Chemical injury was the leading cause of LSCD. Counting the last surgery performed, there were 30 eyes in the Boston KPro group (mean follow-up 14 months), 31 allo-CLET eyes (mean follow-up 33 months), 13 COMET eyes (mean follow-up 10 months), and 11 eyes treated by living-related conjunctival limbal allograft (lr-CLAL, mean follow-up 16 months). Mean follow-up did not differ significantly between groups.

Focusing on visual acuity outcomes, Dr Sangwan reported the result was significantly better for the Boston KPro eyes compared with all other groups. Eyes receiving the Boston KPro had a mean logMAR VA of 2.12 preoperatively with improvement to 0.67. “We have been using the Boston KPro at our centre for about four years. The visual outcomes are impressive in eyes without posterior segment disease, excellent results have also been reported in a published, large international series, and as another advantage, postoperative visual recovery occurs rapidly,” said Dr Sangwan.

“Thanks to improvements in device design, retention rates are also good. However, it remains unclear if bilateral use of the Boston KPro is safe, and my personal opinion is that it may not be a good idea.” Mean logMAR VA improved significantly in eyes that underwent allo-CLET from 1.9 preoperatively to 1.0. In a recently published paper on allo-CLET, Dr Sangwan and colleagues reported that 71 per cent of 29 eyes maintained a completely epithelialised, avascular and stable corneal surface after a mean follow-up of almost five years.

The main drawback of allo-CLET is that patients must receive lifelong immunosuppression that can result in sideeffects and adds cost, said Dr Sangwan.