Exposure of primary orbital implants in postenucleation retinoblastoma patients

Purpose: To determine significant factors influencing the exposure of prima ry orbital implants in patients with retinoblastoma. Design: Retrospective noncomparative case series. Participants: One hundred nine consecutive patients (110 sockets) who had u ndergone enucleation for retinoblastoma from January 1993 to December 1997, Methods: Two patients with recurrence of orbital retinoblastoma were exclud ed from further analysis, leaving 107 patients (108 sockets). The parameter s analyzed included the patient's age; gender; ocular diagnosis; surgeon; t ype, covering, and size of the implant; the use of chemotherapy or radiothe rapy; and the timing of these treatments in relation to enucleation. Study patients were divided into two main groups: the "treated group"-patients wh o had undergone adjuvant external beam radiotherapy or chemotherapy, and th e "untreated group"-patients had undergone enucleation with or without cryo therapy, laser thermotherapy, or brachytherapy to the index or fellow eye. The following additional parameters were noted in the patients with exposed implants: time to exposure from date of enucleation and treatment of expos ure. Main Outcome Measure: Exposure of orbital implants. Results: There were two exposures caused by orbital recurrence of retinobla stoma. The rate of nontumor recurrence exposure was 28% (30 of 108). The me dian time to exposure was 136 days (range, 1-630 days). There were 18 expos ures (35%,18 of 51) in the treated group, with a 34% exposure rate (13 of 3 8) in the chemotherapy group. The exposure rate was 21% (12 of 57) in the u ntreated group. The rates of exposure according to implant were: Vicryl mes h-wrapped hydroxyapatite (2 of 18, 11%), Medpor (8 of 13, 53%), plain polym ethylmethacrylate (PMMA) (4 of 50, 8%), Mersilene-wrapped PMMA (9 of 17, 53 %) and Castroviejo (7 of 10, 70%). Eight of the exposures (27%) were manage d conservatively; the remainder required surgical repair. Conclusions: Results suggested that implant type and covering (P = 0.000) h ad a highly significant effect on the rate of exposure in postenucleation r etinoblastoma patients. There was no statistical evidence that age, gender, ocular diagnosis, surgeon, size of the implant, or radiotherapy had an eff ect on implant exposure. There was an increased rate of exposure in the che motherapy group, although this did not achieve statistical significance (P = 0.058), but a detrimental effect could not be excluded. (C) 2000 by the A merican Academy of Ophthalmology.