Comparative Motility of Retro-scleral and Intrascleral Orbital Implants After Evisceration

Evisceration allows removal of the intraocular contents while preserving the sclera and normal extraocular muscle attachments. It is more advantageous than enucleation in patients in whom intraocular tumor is rules out.

Maximizing orbital volume and restoration of movement are important aspects of a successful surgical outcome.

Standard evisceration techniques do not allow placement of an implant larger than 13-16 mm which don't adequately replace the volume leading to postevisceration socket syndrome. Therefore, various techniques have been described to expand the scleral cavity and allow placement of a large implant including anterior sclerotomies, posterior sclerotomies, and disinsertion of optic nerve.

Implant exposure is a terrible complication of evisceration with reported rates as high as 67%. Exposure of the implant can lead to infection, which usually mandates removal of the implant. Trying to minimize this risk, physicians intentionally place the implants posterior to the normal position of the globe. Some authors described placement of the implant posterior to posterior sclera which totally eliminated the risk of exposure.

However, this deep seating of the implant may have deleterious effects on its motility. It can decrease implant-prosthesis interaction. In addition, retro-scleral placement of the implant moves it posterior to the pulleys that serve as the functional origins of rectus muscles. This relationship would be expected to alter the pulling directions of the rectus muscles after evisceration hindering effective implant motility.