Deep lateral bony decompression of the orbit using a 3D printed ruler

Relevance The issue of the accuracy of intraoperative assessment of the volume of bone mass removed during GLKDO remains relevant. It is known to use devices manufactured by 3D printing for this purpose [1–4]. Objective To present the capabilities of the new GLKDO method. Material and methods Patient A. with EOP and optic neuropathy on the left. Exophthalmos: on the right 22 mm, on the left 25 mm, best-corrected visual acuity (BCVA) OD = 1.0. BCVA OS = 0.2. Signs of decreased contrast sensitivity on the left are observed. Data of computer perimetry 30-2 of the right eye MD = –0.6 dB, left eye MD = –13.3 dB. GLKDO was performed at the Federal State Budgetary Scientific Institution “M.M. Krasnov Research Institute of City Hospital”. Based on an individual stereolithographic model repeating the topography of the lateral wall of the orbit, a measuring device 1.7 mm thick was manufactured with a working part corresponding to the distance from the edge of the outer wall of the orbit to the anterior border of the middle cranial fossa and with a protrusion at the proximal end of the working part 4.7 mm long, 1.6 mm wide and a fixing part congruent to the edge of the outer wall of the orbit. Intraoperatively, the working part of the measuring device was inserted along the lateral wall of the orbit. The depth of possible surgical removal of bone from the "dead space" was estimated by the magnitude of the tip protrusion above the bone surface. Results One month after the operation, BCVA OS = 0.7, computer perimetry data of the left eye MD = -3.3 dB, increased contrast sensitivity of the left eye. Signs of a decrease in the degree of compression on the optic nerve are observed according to the assessment of visual acuity, computer perimetry, and assessment of contrast sensitivity. According to the axial MSCT of the orbit after 1 month, the residual bone thickness in the area of ​​impact = 1 mm. Conclusion Modification of the GLKDO using a measuring device for assessing the depth of surgical impact, manufactured by 3D printing, allows for full-fledged GLKDO with minimal risk of damage to the dura mater. Key words: endocrine ophthalmopathy; optic neuropathy; 3D modeling; stereolithography