Enucleation by the myoconjunctival technique using a silicone implant provides a safe and a cost-effective alternative procedure with prosthesis motility comparable to biointegrateble implants while minimizing the complications. In this video, we demonstrate this simple method of enucleation by the myoconjunctival technique in a 4-year-old child with retinoblastoma in the left eye.
Presentation: Dr. Raksha Rao, Centre for Sight, Hyderabad, India
Surgeon: Dr. Santosh G. Honavar, Centre for Sight, Hyderabad, India
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Enucleation is performed for various indications. An intraocular tumor, a blind, painful eye, a severely traumatized eye, or a deformed, phthisical eye without visual potential. For an ophthalmic surgeon, the goal following enucleation is to provide an optimal match for the contralateral eye and restore the natural appearance. The characteristics of an ideal anophthalmic socket include a centrally placed well-covered implant of adequate volume, a socket lined with healthy conjunctiva, deep fornices to help retain the prosthesis, normal eyelid position with symmetric lid crease, good implant motility, which is transmitted to the overlying prosthesis, and a prosthesis that matches the other eye. A well planned surgical technique with adequate volume replacement provides gratifying static cosmesis. However, optimizing prosthesis motility can be challenging. Currently available implants can be categorized as non-integrated: are the implants that do not integrate with either prosthesis or the orbital tissues. Semi-integrated are the implants that integrate with either the prosthesis or the orbital tissues. Integrated are the implants that integrate with both the prosthesis and the orbital tissues. Biointegrated are the implants that induce fibrovascularization within their substance, and thus get integrated. Biogenic are the implants that are of biological origin. Porous implants, although in wide use, have many complications. The raised cost of these implants was also a major concern. A traditional non-integratable sphere, when wrapped and centered in the muscle cone, and connected to the rectal muscles, offer some prosthesis motility. However, such a procedure requires the use of specifically processed human donor sclera, pericardium, or fascia lata. Again, these raise the cost of surgery significantly. Enucleation via the myoconjunctival technique, using a silicone implant, provides a safe and cost effective alternative procedure, with prosthesis motility comparable to biointegratable implants, while minimizing the complications. The surgery is usually performed under general anesthesia. It is important for the surgeon to review the patient’s medical record and perform a thorough examination, including indirect ophthalmoscopy if possible, to ensure that the correct eye is being enucleated. After the patient is prepared and draped, a wire speculum is placed to exclude the eyelashes from the field. A lateral canthotomy is performed. A 360 degree peritomy is performed at the limbus, using a blunted Westcott scissors, preserving as much of conjunctiva as possible. Anterior Tenon’s fascia is separated from the sclera. Blunt dissection with a 15-degree curved blunted tenotomy scissors in four quadrants between rectal muscles separates deep Tenon’s fascia. The muscles are isolated in the following sequence: Medial rectus, inferior rectus, lateral rectus, superior rectus, superior oblique, and inferior oblique. Each of the rectal muscles is identified, hooked, and double tied, first with 4-0 silk suture just short of the muscle insertion, and then with 6-0 vicryl suture, about 6 millimeter distally. Special care is taken not to accidentally perforate the eye while passing the sutures. Each of the rectal muscles is then transected at a point between the two sutures. Bipolar radio frequency cautery is used to minimize bleeding. 4-0 silk sutures serve as traction sutures, while 6-0 vicryl sutures will later be used to suture the muscles through the conjunctiva. Superior oblique and inferior oblique muscles are hooked and transected and allowed to retract posteriorly. A conjunctival relaxing incision is made temporally for easy manipulation. The eyeball is prolapsed between the blades of the wire speculum to put the optic nerve at a gentle stretch. With a gentle forward traction on the eyeball using the four silk sutures, a 15 degree curved blunted tenotomy scissors is introduced from the lateral aspect between the lateral rectus and the eyeball. Or a straight scissors, introduced from the medial aspect, is an appropriate alternative. The optic nerve is palpated with the closed tip of the scissors, while maintaining gentle traction on the eyeball. The scissors is moved posterior to touch the orbital apex, while strumming the optic nerve. The blades of the scissors are open to straddle the optic nerve, and the nerve is transected with one bold cut. Our case being retinoblastoma, the transection was performed 2 millimeter anterior to the superior orbital fissure to gain a good optic nerve length while avoiding injury to the superior orbital fissure contents. This maneuver generally provides at least 15 millimeter long optic nerve stump. Enucleation spoon and a heavy enucleation scissors, if used, limits space for maneuverability, and results in a shorter optic nerve stump. Hemostasis is achieved by pressure. Deep orbital packing does distort the posterior Tenon’s layer, and is often not necessary. The enucleated eyeball is carefully inspected for intra or perineuritic optic nerve invasion by the tumor, and full thickness scleral or extraocular extension. The length of the optic nerve stump is documented. The eyeball is placed in 10% formalin and submitted for histopathology. An appropriately sized silicone orbital implant is placed posterior to posterior Tenon’s. Size of the implant is governed by the age of the patient, axial length of the eye, whether wrapping is used, and the plane of placement. Posterior Tenon’s is closed with interrupted 6-0 vicryl sutures. Each of the rectal muscles is sutured through the anterior Tenon’s and conjunctiva, just short of its respective fornix, using preplaced double armed vicryl sutures. The suture knots remain exteriorized. These are called myoconjunctival sutures. Anterior Tenon’s is closed with interrupted 6-0 vicryl sutures. Conjunctival closure is done in a continuous key pattern suturing with 6-0 vicryl suture. A snugly fitting conformer is placed, and a median tarsorrhaphy is performed with 6-0 vicryl suture. The suture tarsorrhaphy is removed after one week. The conformer is left in situ until prosthesis is fitted. The socket is generally ready for the placement of a prosthesis in about 4 to 6 weeks. Myoconjunctival technique using a silicone implant is an inexpensive method of enucleation, with minimal complications. Implant exposure and migration are very uncommon. This technique may also be used in those requiring periorbital radiotherapy following surgery. It offers an excellent lifelike quality to the prosthesis by providing a static and dynamic match with the contralateral eye.
March 8, 2018