The ideal ocular prosthesis: analysis of prosthetic volume.

PURPOSE

An ocular prosthesis should complement the volume of the intraconal implant to achieve complete replacement of the volume that is removed by enucleation. This study investigates the limitations on the prosthetic volume in achieving this goal.

METHODS

Prosthetic volume and thickness were measured in 70 patients who underwent enucleation. Patients in group 1 (n = 17) were adults enucleated in childhood, and patients in group 2 (n = 53) were enucleated as adults. Clinical problems after enucleation were documented to determine problems potentially related to prosthetic volume.

RESULTS

None of the ocular prostheses in this patient series was greater in volume than 4.2 ml (range, 0.75-4.2 ml). The average prosthetic volume for patients with implant diameters of 14 mm to 22 mm was 2.2 ml. A prosthetic volume > or =1.8 ml provided an anterior to posterior dimension of 7 mm. Anterior malposition of the implant and the presence of severe socket contraction were noted in patients with the smallest and the thinnest prostheses. In group 2, larger prostheses were associated with ptosis and lower eyelid laxity (p < 0.05; p < 0.01).

CONCLUSIONS

One should not depend on the ocular prosthesis to supply more than 4.2 ml of volume in the anterior compartment of the socket. Adult patients with normal bony development, noncontracted sockets, and an average axial length should not receive implant sizes <20 mm, if one intends to achieve complete replacement of the volume removed by enucleation. Children should receive the largest implant possible.