Anophthalmic socket and orbital implants. Role of CT and MR imaging

Orbital implants: potential new directions

This article reviews orbital implants used to replace an eye after enucleation or evisceration. Advantages of implant placement are described, with discussion of implant and wrap material, and design features that affect clinical outcomes. Implants may be porous or nonporous, pegged for linkage with a cosmetic shell or unpegged, and may be wrapped with a covering material or tissue or unwrapped. Device shape, volume and material qualities affect tissue tolerance and the risk of exposure or extrusion. Limitations of currently available devices are discussed, with factors affecting surgeon and patient choice. Ideally, a device should be easy to insert, avoid the need for wrapping or adjunctive tissues, be light, biointegratable, comfortable after implantation and provide satisfactory orbital volume replacement, movement and cosmesis without requiring further surgery or pegging. This review briefly discusses developments in implant design and aspects of design that affect function, but is not a detailed clinical review; rather, it aims to stimulate thought on optimal design and discusses recent developments. Novel technology in the form of a prototype device with a soft, biointegratable anterior surface is described as an example of newer approaches.

Congenital anophthalmia and microphthalmia: epidemiology and orbitofacial rehabilitation

Objective

To describe the prevalence of congenital anophthalmia and microphthalmia in Hospital Universitario La Paz, and to identify associated risk factors and evaluate cosmetic results in treated and nontreated patients.

Methods

A retrospective, descriptive, cross-sectional study of patients treated with orbital expanding techniques (cases) and nontreated patients (controls) was carried out as a comparative case series study. A total of 36 patients with unilateral or bilateral anophthalmia or microphthalmia as main diagnosis were included; 52 epidemiological and management variables for each patient were analyzed. The study evaluated orbital growth and facial symmetry.

Results

The overall cosmetic result in the study’s group of patients was satisfactory: 66.7% showed good or very good orbital growth, and 75% showed good or very good facial symmetry. Controls had better cosmetic outcome but showed more cataracts (P = 0.05), inferior colobomas (P = 0.026), and family history (P = 0.056) than the cases. Controls also showed significantly better orbital growth (P = 0.042) and facial symmetry (P = 0.014) than the cases.

Conclusion

This study suggests that the mere presence of a globe (controls) still provides better orbitofacial development than the artificial stimulation (cases) currently available for patients with congenital anophthalmia and microphthalmia, who receive internal and external orbital rehabilitation.

Evaluation of the position and function of aqueous drainage implants with magnetic resonance imaging

PURPOSE

To evaluate position and function of antiglaucomatous Ahmed and Molteno shunts using magnetic resonance imaging with head and surface coils.

METHODS

Eight patients (5 males) with shunt implants were included, 4 with Ahmed (FP-7) and 4 with Molteno (s1, single plated). All patients were operated at least 6 months before imaging. In 3 cases (2 with Molteno and 1 with Ahmed shunt), the intraocular pressure (IOP) was above 21 mm Hg, despite maximal medical treatment. The shunt endplate, tube and filtering blebs were identified in T1-weighted and T2-weighted images with both head and surface coils. Volumetric measurements of the orbits, eyeball, and filtering bleb and calculation of the endplate position along sagittal, transverse, and vertical axes were performed in T1-weighted and T2-weighted images using head coils.

RESULTS

The shunt endplate was identified in T1-weighted and T2-weighted images (head coils) as a low intensity (dark) circumlinear band at the superotemporal aspect of the eyeball, surrounded by a pocket of water density, corresponding to the filtering bleb. The anterior position of the endplate, and smaller volume of the orbital cavity (less available orbital space) were associated with higher IOP. Filtering bleb volume was inversely correlated with IOP. In the unsuccessful cases, filtering bleb was absent.

CONCLUSIONS

Magnetic resonance imaging provides insights into the mechanism of aqueous outflow and causes of failure of shunts. A lower orbital volume is associated with anterior position of the shunt endplate and poor shunt performance.

Congenital bilateral microphthalmos after gestational syphilis

Congenital microphthalmos and anophthalmos are currently considered rare conditions. Many infectious agents have been previously associated with these pathologies, but rarely Treponema pallidum. We report a case of bilateral microphthalmos in which her mother presented gestational syphilis.

Medical imaging in pediatric ophthalmology

The use of CT and MR imaging has improved the understanding of many congenital and acquired conditions in pediatric ophthalmology, resulting in more appropriate therapeutic intervention and giving insight into the pathogenesis of these conditions.

Advances in imaging in oculoplastics

Color Doppler imaging, computed tomography (CT) and magnetic resonance (MR) imaging are the most precious imaging tools for the clinician in the field of oculoplastics. Orbital and facial vasculature, with its dynamic changes and flow velocities seen in orbital varices, carotid-cavernous fistulas, and dural cavernous arteriovenous malformations, is best detected by Color Doppler imaging. Computed tomography remains the dominant imaging modality in the evaluation of orbital trauma. Helical CT axial scanning with multiplanar reconstruction and three-dimensional CT imaging are most helpful in assessing iatrogenic, traumatogenic, and teratogenic orbital abnormalities. Despite its poor histologic specificity, MR imaging provides superior soft tissue contrast, and contrast-enhanced MR imaging has an established role regarding soft tissue tumor infiltration. The greatest value of MR studies in the evaluation of orbital and palpebral tumors is that it has the capacity to show the precise relation between lesions and adjacent structures before the clinician contemplates a surgical approach. Finally, contrast-enhanced MR imaging proved to be a valuable vascularization indicator based upon the extent of relative enhancement within porous orbital implant in anophthalmic socket.