![]() The accurate placement of the electronics case is critical, as errors in the distance measurements will ultimately determine the length and orientation of the cable when the array is tacked to the retina. The eyelet markings around the metal electronics case should be superotemporal, midquadrant, and radially oriented in relation to the center of the cornea. Second Sight provides a nomogram for the placement of the sutures based on the axial length of the eye. The electronics package and coil are secured with 5-0 nylon or polyester fiber (Mersilene, Ethicon) sutures at designated locations posterior to the limbus. This allows mobility and flexibility of the electronics case during eyelet suturing, which is important for accurate placement in the middle of the superotemporal quadrant. Pearl: Allow slack in the buckle so it has positioning flexibility as the eyelet tabs are sutured to the sclera. Pass the band through the scleral tunnels or suture it nasally and connect it with a Watzke sleeve in the superonasal quadrant. This allows the surgeon to titrate the level of force. To avoid the risk of damaging the coil with a metal instrument, a fingertip can be used to manipulate the coil. Pearl: Placing the coil under the lateral rectus can be challenging because it is relatively large. Place the receiving coil under the lateral rectus muscle, pass the inferior portion of the band under the inferior and medial rectus, then pass the superior portion of the band under the superior rectus. Pearl: Using scleral tunneling nasally will minimize sutures, thereby lessening the long-term chance of suture erosion. Once the peritomy has been performed and the rectus muscles have been isolated, the surgeon begins placement of the extraocular components by positioning the band under all the rectus muscles and securing the device to the sclera. Keep the cornea well lubricated and consider using a corneal protector. Pearl: Take extra care to protect the cornea from drying, which would make the intraocular and tacking portion of the procedure much more difficult. The temporal conjunctiva and Tenon capsule should remain intact to cover the bulk of the implant, which will be placed temporally. Pearl: If necessary, make only a nasal relaxing incision and avoid cutting the temporal conjunctiva. It is also important to avoid cautery at the intended sclerotomy site temporally. It is critical that the implant be well covered by the conjunctiva to prevent erosion in the long term. At the start of the procedure, long suture tags are placed on the conjunctival edge to help identify the edge at the end of the procedure. PREPARATIONįirst, a limbal peritomy is performed, and the rectus muscles are isolated. Following are some tips we have found helpful in the implantation of the Argus II. ![]() The procedure is performed under general anesthesia and takes approximately 4 hours. The epiretinal electrode array that stimulates the photoreceptor cells is fixed to the retinal surface with a tack. A receiver and transmitting coil and a case containing electronic components is fixed to the scleral surface. The implanted device consists of extraocular and intraocular components. This device delivers electrical stimulation to the retina to induce visual perception and is generally implanted in the eye with worse visual acuity. Thanks to advances in science and technology, these patients may regain some functional vision with a retinal implant (Argus II Retinal Prosthesis System, Second Sight Medical Technology). Patients with RP experience a gradual decline in visual acuity caused by the death of photoreceptor cells. Retinitis pigmentosa (RP) is a group of inherited diseases that cause retinal degeneration. In preparation for the tacking procedure, raising the patient’s intraocular pressure to between 60 mm Hg and 80 mm Hg will minimize bleeding.The array should cover the macular center at approximately 45°.The conjunctiva must fully cover a retinal implant to prevent long-term erosion.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |