Purpose: To determine significant factors influencing the exposure of primary orbital implants in patients with retinoblastoma.
Design: Retrospective noncomparative case series.
Participants: One hundred nine consecutive patients (110 sockets) who had undergone enucleation for retinoblastoma from January 1993 to December 1997.
Methods: Two patients with recurrence of orbital retinoblastoma were excluded from further analysis, leaving 107 patients (108 sockets). The parameters analyzed included the patient's age; gender; ocular diagnosis; surgeon; type, covering, and size of the implant; the use of chemotherapy or radiotherapy; and the timing of these treatments in relation to enucleation. Study patients were divided into two main groups: the "treated group"-patients who had undergone adjuvant external beam radiotherapy or chemotherapy, and the "untreated group"-patients had undergone enucleation with or without cryotherapy, 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 exposure.
Main outcome measure: Exposure of orbital implants.
Results: There were two exposures caused by orbital recurrence of retinoblastoma. The rate of nontumor recurrence exposure was 28% (30 of 108). The median time to exposure was 136 days (range, 1-630 days). There were 18 exposures (35%,18 of 51) in the treated group, with a 34% exposure rate (13 of 38) in the chemotherapy group. The exposure rate was 21% (12 of 57) in the untreated group. The rates of exposure according to implant were: Vicryl mesh-wrapped hydroxyapatite (2 of 18, 11%), Medpor (8 of 13, 53%), plain polymethylmethacrylate (PMMA) (4 of 50, 8%), Mersilene-wrapped PMMA (9 of 17, 53%) and Castroviejo (7 of 10, 70%). Eight of the exposures (27%) were managed conservatively; the remainder required surgical repair.
Conclusions: Results suggested that implant type and covering (P = 0.000) had a highly significant effect on the rate of exposure in postenucleation retinoblastoma patients. There was no statistical evidence that age, gender, ocular diagnosis, surgeon, size of the implant, or radiotherapy had an effect on implant exposure. There was an increased rate of exposure in the chemotherapy group, although this did not achieve statistical significance (P = 0.058), but a detrimental effect could not be excluded.