Long-term outcomes of the aphakic snap-on Boston type I keratoprosthesis at the Bascom Palmer Eye Institute

Figures & data

Table 1 Demographical information, indications, and previously diagnosed comorbidities in patients receiving an aphakic Boston snap-on type I keratoprosthesis at the Bascom Palmer Eye Institute

Ocular history	Group (n=45)
Demographics
Number of eyes	45
Mean age at surgery (years ± SD)	66.7±16.8
Females, n (%)	23 (51)
Right eye, n (%)	28 (62)
Prior corneal grafts
Prior failed graft, n (%)	40 (89)
Number of previously failed grafts, n ± SD	2.5±1.0
Underlying corneal pathologya
Glaucoma related, n (%)	11 (24)
Aphakic or pseudophakic bullous keratopathy, n (%)	7 (16)
Thermal/chemical burn, n (%)	4 (9)
Herpetic keratitis, n (%)	4 (9)
Uveitis, n (%)	4 (9)
Keratoconus, n (%)	2 (4)
Fuch’s endothelial dystrophy, n (%)	2 (4)
Stevens–Johnson syndrome, n (%)	2 (4)
Retinal detachment related, n (%)	2 (4)
Aniridia, n (%)	1 (2)
Corneal ulcer, n (%)	1 (2)
Corneal exposure, n (%)	1 (2)
Endophthalmitis, n (%)	1 (2)
Irido-corneal-endothelial syndrome, n (%)	1 (2)
Mooren’s ulcer, n (%)	1 (2)
Riley day syndrome, n (%)	1 (2)
Contralateral eye
No significant pathology, n (%)	6 (13)
Visually impaired/legal blindness, n (%)	26 (58)
Blind/anophthalmic, n (%)	13 (29)
Preoperative lens status
Pseudophakia, n (%)	25 (56)
Aphakia, n (%)	19 (42)
Iris status
Aniridia, n (%)	14 (31)
Ocular and surgical history
Underlying glaucoma, any type, n (%)	34 (76)
Prior glaucoma drainage implant, n (%)	25 (26)
Previous vitrectomy, n (%)	12 (27)

Note:

a In patients with multiple ocular comorbidities, the most likely primary etiology leading to the need for KPro implantation was listed.

Abbreviations: Kpro, keratoprosthesis; n, number.

Table 2 Concomitant surgeries: concurrent surgical procedures performed at the time of implantation of the aphakic Boston snap-on type I keratoprosthesis

Concomitant surgeries	n=45
Vitrectomy
Anterior vitrectomy, n (%)	18 (40)
Pars plana vitrectomy, n (%)	20 (44)
Previous PPV without repeat PPV at KPro implantation, n (%)	7 (16)
Glaucoma
Ahmed drainage implant, n (%)	9 (20)
Molteno drainage implant, n (%)	6 (13)
Endocyclophotocoagulation, n (%)	2 (5)

Abbreviations: Kpro, keratoprosthesis; n, number; PPV, pars plana vitrectomy.

Figure 1 Kaplan–Meier survival graph of vision in patients receiving a Boston aphakic snap-on type I keratoprosthesis for the first 5 years of follow-up.

Notes: (A) Retention of 20/200 vision over the follow-up period. (B) Maintenance of the initial visual gain over time. (C) Survival from any complication. (D) Survival from any posterior segment complication (retinal detachment, endophthalmitis, and epiretinal membranes).

Figure 2 Kaplan–Meier survival graph of the most frequent complications in patients receiving an aphakic Boston snap-on keratoprosthesis during the first 5 years of follow-up.

Notes: (A) Retroprosthetic membranes that required intervention during the follow-up period. (B) Survival from corneal melts. (C) Survival from keratoprosthesis extrusion or removal (retention). (D) Survival from loss of vision attributed to glaucoma progression. (E) Survival from endophthalmitis or sterile vitritis. (F) Survival from retinal detachments.
Abbreviation: RPM, retroprosthetic membrane.

Figure 3 Visual acuities over time.

Note: The visual acuities improved initially postoperatively, then gradually declined over time.
Abbreviations: CF, count fingers; HM, hand motion; LP, light perception; NLP, no light perception; Preop, preoperatively; Postop, postoperatively.