Three-Dimensionally Printed Conformers for Treatment of Congenital Anophthalmos

    loading  Checking for direct PDF access through Ovid

Excerpt

Management of congenital anophthalmos, absence of an eye due to an embryonic developmental defect,1 requires treatment with orbital implants soon after birth to prevent growth deprivation of the orbital bones, possibly resulting in facial asymmetry, and to create space to place a natural-looking prosthesis.2 We believe that the risks of socket contraction and scarring are minimal during regulated expansion obtained with exchange of stepwise size increasing conformers. However, this process is very labor intensive for hand-made conformers and proper fit may require general anesthesia.3 Here, we show that these limitations can be overcome using serial three-dimensional (3D) printing. A series of increasing-size conformers was 3D-printed with a stereolithography printer (Rapid Shape GmbH, Heimsheim, Germany) and NextDent Ortho Rigid, a biocompatible (class IIa) polymethyl methacrylate. Conformer design was based on horizontal eyelid size and visual inspection of the socket and drawn with Solid Works (Dassault Systèmes, Vélizy-Villacoublay, France) and Meshmixer (Autodesk Inc., San Rafael, CA, USA). A wing-shaped extension was added to the design and a series of increasing-size conformers was derived by upscaling dimensions. A Caucasian male patient was diagnosed with unilateral anophthalmos with a cyst-like rudimental remnant (5.7 × 4.4 mm) on the left and normal morphology on the right. At the age of 2 months, the first conformer was fitted in an outpatient procedure without anesthesia or sedation. The parents were instructed to try a larger model each week. The medical ethical committee of the VU University Medical Center approved the study. The parents of the patient gave written informed consent. Over a six-and-a-half-month time period, 5 sequential 3D-printed conformers were fitted until sufficient space was created to wear a cosmetic prosthesis. The conformers were well tolerated and no adverse effects were encountered. Conformer start volume (0.449 ml) was 3.76 times smaller compared with end volume (1.69 ml), indicating increasing socket volume over time. The horizontal palpebral fissure increased from 9.0 mm to 19.0 mm, respectively, 56% and 83% of the unaffected side. We compared the patient´s horizontal palpebral fissure with values from a healthy population consisting of Caucasian Americans,4 showing that the horizontal palpebral fissure of his unaffected eye was between the 5th and 95th percentile and of his affected eye at 96% of the 5th percentile (Fig.). These results indicate that the conformers successfully stimulate socket expansion and palpebral fissure growth in a comparable growth rate with the contralateral side. Good prosthetic fit is crucial for treatment of anophthalmic sockets as a too small conformer may result in inadequate stimuli for orbit expansion, whereas a too large conformer may cause irritation or scarring of the conjunctiva and may require general anesthesia to force it into the socket. It has been shown that 3D-printing could facilitate conventional prosthesis design.5 In this study, we printed the actual conformer to be used for the treatment of congenital anophthalmos with several advantages over the conventional hand-made treatment, including the ability to print a sequential series of conformers of multiple small-step-sizes therewith facilitating conformer exchange by the parents in the home situation and the ability to gradually change the shape of the conformer which may be required to create a suitably shaped eye cavity for placement of a natural-looking prosthesis. In conclusion, this proof-of-concept study showed that the use of 3D-printed conformers may be promising in providing adequate growth stimuli and is a safe treatment in the most critical early phase of congenital anophthalmia.
    loading  Loading Related Articles