Reedy B K, Pan F, Kim W S, Bartlett S P
Edwin and Fannie Gray Hall Center for Human Appearance, and Department of Pathology, University of Pennsylvania Medical System, Philadelphia, USA.
Plast Reconstr Surg. 1999 Sep;104(3):713-8. doi: 10.1097/00006534-199909030-00015.
Tissue expanders placed within the orbit can have a positive effect on orbital and ipsilateral midfacial growth. To date, there is no precise method for controlling and monitoring expansion to induce normal growth in the developing facial skeleton. The present study was undertaken to determine the optimal physiologic pressure required to stimulate normal orbital growth and to determine whether above-normal growth could be achieved with higher intraorbital pressures. Using a neonatal swine model, an accurate method of monitoring intraorbital pressure, precisely controlling intraorbital expansion, and achieving normal orbital growth was explored. Sixteen male, 3-week-old Yorkshire piglets were randomly divided into three surgical groups. In each group, the left orbit was the experimental side, and the contralateral right orbit served as an untreated control. Group 1 (n = 6) underwent enucleation only. Group 2 (n = 5) underwent enucleation and orbital expansion at a near-normal physiologic pressure of 20 mmHg. Group 3 (n = 5) underwent enucleation and orbital expansion at a supernormal pressure of 60 mmHg. Spherical tissue expanders (10 cc) with a separate injection port were utilized as the orbital expanders. Pressure was monitored by an electronic manometer that was calibrated daily. Morphology of the orbits was documented by photography, the dimensions of the orbits were quantitated by three-dimensional mechanical digitization, and orbital volumes were calculated. In the unexpanded, anophthalmic control group, a significant reduction in radial growth after evisceration was seen. In group 2, the orbit stimulated with a consistent pressure of 20 mmHg, just above the physiologic normal pressure of 17 mmHg, showed an increase in radial dimension of 8 percent compared with the unoperated side. In the high-pressure group of 60 mmHg, an increase of 16 percent in the radius was observed over the 4-week period. This led to a corresponding increase in orbital volumes with increased pressure. Utilizing a paired t test, these differences in the radial and volumetric growth of the orbit were statistically significant (p < 0.005). The results obtained demonstrated a direct relationship between intraorbital pressure and the growth of the bony orbit in the radial dimension. On the basis of this study, we concluded that orbital expansion maintained at normal physiologic pressure can stimulate normal orbital growth in the neonatal facial skeleton. In addition, application of above-normal pressures for expansion can induce accelerated orbital growth.
置于眼眶内的组织扩张器可对眼眶及同侧中面部生长产生积极影响。迄今为止，尚无精确方法来控制和监测扩张过程，以诱导发育中的面部骨骼实现正常生长。本研究旨在确定刺激正常眼眶生长所需的最佳生理压力，并确定更高的眶内压力是否能实现超常生长。利用新生猪模型，探索了一种监测眶内压力、精确控制眶内扩张并实现正常眼眶生长的准确方法。16只3周龄雄性约克夏仔猪被随机分为三个手术组。每组中，左侧眼眶为实验组，对侧右侧眼眶作为未处理的对照。第1组（n = 6）仅接受眼球摘除术。第2组（n = 5）接受眼球摘除术，并在接近正常生理压力20 mmHg下进行眼眶扩张。第3组（n = 5）接受眼球摘除术，并在超常压力60 mmHg下进行眼眶扩张。带有单独注射端口的球形组织扩张器（10 cc）用作眼眶扩张器。压力通过每天校准的电子压力计进行监测。通过摄影记录眼眶形态，通过三维机械数字化测量眼眶尺寸，并计算眼眶体积。在未扩张的无眼球对照组中，可见眼球摘除术后径向生长显著减少。在第2组中，以刚好高于生理正常压力17 mmHg的20 mmHg恒定压力刺激的眼眶，与未手术侧相比，径向尺寸增加了8%。在60 mmHg的高压组中，在4周期间半径增加了16%。这导致眼眶体积随压力增加而相应增加。采用配对t检验，眼眶径向和体积生长的这些差异具有统计学意义（p < 0.005）。获得的结果表明眶内压力与骨性眼眶径向尺寸的生长之间存在直接关系。基于本研究，我们得出结论，维持在正常生理压力下的眼眶扩张可刺激新生面部骨骼中的正常眼眶生长。此外，施加高于正常的压力进行扩张可诱导眼眶加速生长。
