Orbital trauma.

This article is a review of recent advances in the evaluation and treatment of orbital and periorbital trauma. We present the pertinent literature from the past year dealing with orbital injuries, orbital imaging, assessment and management of orbital fractures, and traumatic optic neuropathy. Managing orbital trauma can utilize different approaches to achieve the same final goal: the restoration of normal orbital and craniofacial anatomy and the return of function. We provide the perspective of our orbital and ophthalmic plastic and reconstructive practice and relate the recent literature to our current treatment of orbital trauma. We find that often a multidisciplinary effort is advantageous for managing complex orbital and craniofacial injury.

The effect of maturation on the ability to stimulate orbital growth using tissue expanders in the anophthalmic cat orbit.

Tissue expanders were used to stimulate orbital growth at different stages of maturity in the immature anophthalmic cat orbit. Twelve cats had the right globe enucleated at 2 weeks of age and tissue expanders implanted in the orbit. The cats were randomized into four groups (A, B, C, and D). The tissue expanders remained in the nonexpanded state for a preassigned length of time. Orbital volume was determined on each cat using computed tomography (CT) immediately prior to expansion of the implant. Expansion began at age 10 weeks for group A, 15 weeks for group B, and 25 weeks for group C and involved 0.7 cc injections of saline at 2-week intervals until a final volume of 4.5 cc was obtained. Group D remained as a nonexpansion control group. Four to 5 weeks after expansion was completed, a second orbital volume CT was obtained on each animal and compared with the pre-expansion CT. The right orbits of group A, had pre-expansion (week 10) orbital hypoplasia with a volume 26.2% smaller than the left control orbits. Postexpansion (week 25), the right orbital hypoplasia had decreased to a volume 10.3% less than the left control orbits. The right orbits of group B had pre-expansion (week 15) orbital hypoplasia with a volume 35.6% smaller than the left control orbits. Postexpansion (week 31), the right orbital hypoplasia had decreased to a volume 25.9% less than the left control orbits. The right orbits of group C had a preexpansion (week 25) orbital hypoplasia with a volume 39.8% smaller than the left control orbits. Postexpansion (week 41), the right orbital hypoplasia had decreased to a volume 29.3% less than the left control orbit. Tissue expanders, expanded in the hypoplastic immature cat orbit stimulated orbital growth and reversed orbital bony hypoplasia to varying degrees. The amount of growth stimulated was inversely proportional to the age at which expansion began. Orbital growth, stimulated by tissue expander expansion, was also demonstrated after the normal age of cat orbit maturation (weeks 28-30).

Exposure rate of hydroxyapatite spheres in the anophthalmic socket: histopathologic correlation and comparison with silicone sphere implants.

We retrospectively reviewed enucleations and secondary anophthalmic socket sphere implantations for a 3 year period. We compared the incidence of exposure of hydroxyapatite implants to the incidence of exposure of silicone implants. We found that the incidence of hydroxyapatite exposure following enucleation was 3 of 27 (11.1%), and following secondary anophthalmic socket implantation was 3 of 32 (9.4%). The incidence of silicone sphere exposure following enucleation was 0 of 48 (0%), and following secondary implantation was 1 of 30 (3.3%). The difference in exposure rate between hydroxyapatite and silicone reached statistical significance in the enucleation group (p = 0.043) and in the combined enucleation and secondary implantation group (p = 0.033), but not in the secondary implantation group when considered separately. Osteoinduction and fibrovascular infiltration were found in all hydroxyapatite specimens examined histopathologically. In the exposed implants, liquefaction necrosis of the implant occurred. In the nonexposed implant, complete fibrovascular ingrowth was noted at 7 months. We believe that the hydroxyapatite anophthalmic sphere is associated with a higher incidence of exposure and postoperative inflammation when compared to silicone anophthalmic spheres. Patient selection and technique modification may reduce the incidence of hydroxyapatite implant exposure.

Extrusion rate of silicone spherical anophthalmic socket implants.

The most popular technique of placement of an anophthalmic spherical implant was first described by Frost and Lange in 1886, and has remained essentially unchanged since that time. That technique incorporates imbrication of recti muscles over an 18 mm spherical implant, and purse stringing of conjunctiva and Tenon's fascia in a single layered closure. The Frost-Lange technique has led to previously reported extrusion rates as high as 11.3%. The technique is also associated with superotemporal implant migration and poor prosthetic motility. Our technique modification includes suturing recti muscles independently to a 20 mm spherical implant reinforced with autogenous fascia or preserved sclera. We then close Tenon's fascia and conjunctiva independently as separate layers. The extrusion rate for our patients during a 10 year study period was 0.84% (1 of 119). We found no implant migration, no painful socket, and prosthetic motility was good. We recommend our technique modification to replace the traditional Frost-Lange technique.

Stimulation of orbital growth by the use of expandable implants in the anophthalmic cat orbit.

We evaluated the efficacy of expandable orbital implants to stimulate bone growth in the anophthalmic cat orbit. Eighteen cats unilaterally enucleated at 2 weeks of age received either expandable orbital implants (groups A1 and A2), solid silicone sphere implants of 12 mm or 8 mm (groups B1 and B2), or no implant (group C). Those cats with expandable implants (group A) had the implant size increased by 0.5 ml injections of saline at 2-week intervals starting at 8 weeks of age until a final volume of 4 cc was reached. Four of the expandable implants were found to be only partially inflated at 20 weeks and were subgrouped A2. At 20 weeks of age, the anophthalmic orbits with fully inflated expanders showed no significant difference in either orbital volume or orbital entrance area when compared with control orbits: volume (91.2%), area (95.7%) (p = 0.01). These same orbits also showed a significant increase in both orbital volume and orbital entrance area when compared with the growth obtained by any other group. These other groups showed growth, expressed as a percentage of normal growth, as follows: partially inflated implant: volume (63.0%), area (69.0%); 12-mm sphere implant: volume (57.0%), area (54.5%); 8-mm sphere implant: volume (46.5%), area (44.6%); no implant: volume (47.6%), area (43.6%) (p = 0.01). This study suggests that the use of expandable orbital implants stimulates bony growth in the immature cat orbit. Bony stimulation was proportional to volume implanted, and expandable orbital implants achieved maximum bony stimulation in the groups studied.