Types of Implants
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Ocular implants provide surgeons with porous biocompatible implants for orbital reconstruction following enucleation. and evisceration . procedures. Surgeons may select from sphere implant diameters of 14mm to 22mm. A resterilizable sizer set is available for selecting the appropriate implant diameter at the time of surgery. It may possibly be easily shaped with a scalpel. Its lightweight property, the biocompatibility of the porous polyethylene, and the ability to place the implant deep in the socket contribute to the overall popularity of various implants. Motility may possibly be enhanced by suturing the extra ocular muscles directly to the implant or to an overlying fascia or scleral wrap. As with all orbital implants, it is important to have a tension free closure over the implant. There are many types of ocular implants used in reconstructive surgery… magnets, gold, silver, glass, silicone, cartilage, bone, fat, cork, titanium mesh, acrylics, wool, rubber, catgut, peat, agar, polyethylene, hydroxyapatite. Many of these implants are described below.
Medpor® Biomaterial
MEDPOR® is comprised of a lightweight, porous form of high-density polyethylene, a material with a long history of medical applications. Its unique, highly porous texture allows vessels to incorporate into the enhancement shape, integrating MEDPOR® into a patient’s tissues. The shape and size can be customized by your surgeon to fit your individual needs. MEDPOR® eliminates the need for grafts or silicone implants. In terms of orbital spheres, surgeons may possibly select from sphere implant diameters of 14 mm to 22 mm. A resterilizable sizer set is available for selecting the appropriate implant diameter at the time of surgery.
COI ®Implants
The Conical Orbital Implant (COI) ® was designed and developed to address numerous common problems associated with the correction of the anophthalmic socket. The COI® design provides removal of the anterior surface of the channels in the medial, lateral and inferior quadrants.
Bio-Ceramic
Bioceramic Orbital Implant are made of the porous, strong, non-brittle biomaterial alumina (Al2 03). These implants feature highly uniform interconnected pores of approximately 500mm in size. The extensive pore system enhances fibrovascular ingrowth which keeps the implant from migrating and allows the secure attachment of extraocular muscles, thereby improving implant motility.
Hydroxyapatite
The Hydroxyapatite (HA) ocular implant is a spherical (ball-shaped) implant composed of natural coralline HA. It is used to replace the volume of the orbit when the eye is surgically removed, or as a replacement implant in patients with a poorly functioning, pre-existing implant. Historically, the use of nonporous synthetic ocular implants has led to complications such as exposure, extrusion, migration, infection, poor motility, and poor cosmesis.
Dermis-Fat Graft
The dermis-fat graft is composed of subcutaneous fat and overlying dermis. Its advantages include the fact that it is an autologous graft and, thus, lacks concerns for bio-compatibility in disease transmission. However, there is a certain degree of fat atrophy which may occur leading to some unpredictability related to loss of volume. Dermis fat graft may possibly be used as a primary procedure following primary reconstruction for orbital exenteration, as a low cost means to provide an orbital implant and in instances in which enucleation.
Dermis-fat graft is often performed early in childhood since the fat may possibly grow and provide stimulus for orbital growth. Dermis fat graft can also be used in numerous secondary procedures such as a replacement of an extruded orbital implant and correction of deep superior sulcus deformity. Surgeon may possibly choose one of several donor sites including the lower abdominal quadrant and the outer quadrant of the buttock. The graft is harvested with an attempt to minimize mechanical manipulation of the graft and to quickly insert the graft into the previously prepared recipient bed. Often the dermis has slight surgical modifications in order to create a dome shape to it which often provides better motility for the prosthetic implant. Complications from dermis fat graft include atrophy, central graft ulceration, granuloma formation, cyst formation, keratinization, hair growth, symblepharon, or/and donor site morbidity.
