Vitreoretinal Complications Frequent After KPro Implantation

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Potentially blinding secondary complication duration can average 17.7 months, the study shows.

Keratoprosthesis devices are widely used to treat corneal blindness and can produce remarkable vision improvements for many, according to a report; however, retinal complications are reported in a majority of these patients, the American Journal of Ophthalmology study adds. A small number of studies have explored vitreoretinal setbacks after implantation of Boston Type 1 Keratoprosthesis, or KPro, but samples have been small. This research provides a large interventional case series.

The review examines charts for 132 eyes (114 patients) who received the KPro implant at Centre Hospitalier de l’Université de Montréal, Quebec, Canada from 2008 to 2017. Follow-up was at least 12 months, with the average time to final visit 68.2 months. This study found significant vision improvements in eyes with no vitreoretinal complications (NVRC), although also for those with vitreoretinal complications (VRC). In mean values, best-corrected visual acuity (BCVA) increased in the NVRC group from baseline to last visit; 1.74 logMAR to 1.33 logMAR, and in the VRC group from 1.74 to 1.52 logMAR.

At baseline, 3% of eyes displayed acuity sharper than legal blindness — 20/200 — compared with 36.4% that had better than 20/200 vision at the final visit. Although visual gains were significant, 61.4% of eyes experienced vitreoretinal complications, some sight-threatening, the report explains. The events occurred at a mean of 17.7 months after surgery. These findings reaffirm “the importance of close monitoring to ensure early detection of secondary complications, necessary during the early postoperative period up until 1.5 years postoperatively.”

The most frequent complication was retroprosthetic membrane formation (RPM), found in 38.6% of eyes (n=51), occurring at a mean of 18.3 months after implantation. These eyes were treated primarily with Nd: YAG membranectomy. Retinal detachment (RD), the next most frequent postoperative setback, was the only complication linked to worse final outcomes (P =.001) in a univariate calculation. From baseline, eyes with postoperative RD displayed reduced acuity by 0.30 logMAR, but participants without RD showed a gain of 0.40 logMAR.

RD developed in 15.2% of eyes (n=20), 30.8 months after surgery. For 19 patients with available outcome data, 42.1% had detachment located at the macula, and 31.6% displayed RD off the macula. Treatment included pars plana vitrectomy (PPV) or pneumatic retinopexy. Specifically, for those with post-surgery RD, position relative to the macula and treatment were less associated with final outcome than preoperative glaucoma diagnosis, the study explains. 

Cystoid macular edema (CME) was displayed in 12.1% of eyes, 23.9 months after implantation. CME after KPro typically happens “later and is less responsive to treatment” than when it occurs after cataract surgery. Endophthalmitis arose in 9.1% of eyes, with 70% of cases culture-positive. Infection resolved for 66.7% with intravitreal antibiotics, or antibiotics in combination with PPV. Sterile vitritis was experienced by 7.6% of eyes, 22.5 months after surgery and was successfully treated in all those affected by using topical steroids or steroids along with PPV.

A number of patient charts lacked complete outcome data, representing a limitation of this study. Strengths of the analysis included an independent reviewer blinded to identifying information, and a long follow-up period. On the basis of duration from implantation to onset of each complication, frequent monitoring appears essential, the research adds.


Khair D, Salimi A, Harissi-Dagher M. Vitreoretinal complications in Boston keratoprosthesis type 1. Am J Ophthalmol. Published online June 5, 2021. doi:10.1016/j.ajo.2021.06.002