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Microhook ab interno trabeculotomy, a novel minimally invasive glaucoma surgery, in eyes with open‐angle glaucoma with scleral thinning

2015; Wiley; Volume: 94; Issue: 5 Linguagem: Inglês

10.1111/aos.12888

1755-3768

Masaki Tanito, Ichiya Sano, Yoshifumi Ikeda, Etsuko Fujihara,

Ocular Surface and Contact Lens

A 63-year-old woman with steroid-induced glaucoma presented to our hospital with high intra-ocular pressure (IOP) in both eyes (OU). She had been treated with systemic prednisolone and topical betamethasone for 2 years for scleritis OU that associated with relapsing polychondritis. At referral, the best-corrected visual acuity (BCVA) was 0.5 in the right eye (OD) and 1.2 in the left eye (OS); the respective IOP values were 36 and 32 mmHg with topical 2% carteolol. No signs of active scleritis or intra-ocular inflammation were observed; however, patchy scleral thinning (Fig. 1A,B, white arrows) due to previous nodular scleritis and secondary cataract was observed OU. Because of the scleral thinning and the possibility of recurrent scleritis, the glaucoma surgeries that require creation of a scleral flap were unsuitable for this case, and therefore, trabeculotomy with an ab interno technique in combination with cataract surgery was performed OU (Video S1). Before trabeculotomy, phacoemulsification/aspiration and intra-ocular lens implantation were performed through a 2.4-mm-wide clear corneal incision. The anterior chamber was filled with a viscoelastic material to stabilize the chamber depth. Under visualization using a Swan–Jacob gonioprism lens (Ocular Instruments, Bellevue, WA, USA), a small goniotomy was created in the temporal angle using a 20-gauge microvitreoretinal (MVR) knife (Mani, Utsunomiya, Japan) inserted through the opposite side corneal side-port; the tip of a straight Sinskey microhook (Inami, Tokyo, Japan) then was inserted into Schlemm's canal at the goniotomy site (Fig. 1C, black arrow) and moved circumferentially towards both the superior (Fig. 1D) and inferior sides to incise the inner wall of Schlemm's canal and trabecular meshwork over 3 clock hours. The same trabeculotomy procedure was repeated in the nasal angle over 3 clock hours. No complications other than early postsurgical hyphema (Fig. 1E,F) developed perioperatively. The postoperative IOPs ranged between 7 and 10 mmHg OD and 8 and 14 mmHg OS. At the final visit 4 months postoperatively, the BCVA was 1.0 OU and the IOP was 8 mmHg OU with 2% carteolol, topical 0.1% betamethasone twice daily and 7 mg oral prednisolone. No cyclodialysis was evident by gonioscopy and ultrasound biomicroscopy; cleft of trabecular meshwork was observed at the trabeculotomy sites OU by anterior segment optical coherence tomography (Fig. 1G, arrow). After a trabeculotomy greater than 180 degrees, marked IOP reduction was achieved OU in the current case. As reported regarding ab externo trabeculotomy (Iwao et al. 2011), patients with steroid-induced glaucoma also may be good candidates for microhook ab interno trabeculotomy. Several techniques of ab interno trabeculotomy or gonio-bypass surgeries using the Trabectome (Neo-Medix, Tustin, CA, USA) (Minckler et al. 2005), iStent (Glaukos, Laguna Hills, CA, USA) (Malvankar-Mehta et al. 2015) and gonioscopy-assisted transluminal trabeculotomy (Grover et al. 2014) have been reported. These techniques also were indicated for the current case; however, the absence of the need for expensive or special devices is an advantage of our procedure. To minimize the damage of outer wall of Schlemm's canal, we recommend the surgeon to make an initial goniotomy by scratching the trabecular meshwork surface using the tip of MVR knife rather than cutting. The tip of the Sinskey hook can be observed thorough the trabecular meshwork under the visualization using a Swan–Jacob gonioprism lens with enough high magnification. To avoid unintended tissue damage around the trabecular meshwork, after the insertion of a microhook into the Schlemm's canal, correct insertion, direction and depth of the tip of hook should be carefully monitored during the procedure. The microhook ab interno trabeculotomy, a minimally invasive glaucoma surgery that targets the outflow pathway while sparing the conjunctiva without scleral dissection, can be a surgical option in cases of open-angle glaucoma with scleral thinning. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.