Gonioscopy-Assisted Transluminal Trabeculotomy for Myocilin-Associated Juvenile Open-Angle Glaucoma: A Case Series of 8 Eyes Over 2.2 to 4.1 Years.

Objective: Mutations within the myocilin (MYOC) gene are the first known single-gene cause of both primary open-angle glaucoma and juvenile open-angle glaucoma (JOAG). Subsequent studies have shown these mutations cause trabecular meshwork dysfunction, resulting in markedly elevated intraocular pressures (IOPs) at young ages. Angle-based procedures, like gonioscopy-assisted transluminal trabeculotomy (GATT), bypass the trabecular meshwork, and as such, are hypothesized to be particularly effective in this angle-based disease. The purpose of this case series is to evaluate the efficacy of GATT for MYOC-associated JOAG.

Design: A retrospective chart review was performed evaluating patients under the age of 18 years with known MYOC-associated JOAG who underwent GATT. A total of 8 eyes of 4 children are included.

Participants: All participants had a strong family history of MYOC glaucoma.

Methods: All patients underwent a thorough clinical evaluation, including visual acuity, slit lamp examination, optic nerve fundoscopy, and IOP measurements by Goldmann applanation. Most patients also underwent 24-2 Swedish Interactive Thresholding algorithm (SITA) standard Humphrey visual fields and fundus photography, and all patients had retinal nerve fiber layer OCT.

Main outcome measures: Main outcome measures include IOP and number of medications. Additional measures include visual acuity, optic nerve photos, visual field testing, and OCT.

Results: Following 360° GATT, all 8 eyes of 4 children had a mean drop in IOP of 26 mmHg (68%), and all were able to stop glaucoma medications entirely. Our patients were followed up between 2.2 and 4.1 years with no evidence of decreasing efficacy or glaucomatous progression. All patients maintain 20/20 visual acuity or better in both eyes, and glaucoma has stabilized on all available ancillary testing (OCT, Humphrey visual field, and optic nerve photos). One patient (patient 4) had a notable reversal of cupping.

Conclusions: In MYOC-associated JOAG, the pathology is concentrated at the trabecular meshwork (TM), lending itself well to angle-based surgeries, especially GATT. Gonioscopy-assisted transluminal trabeculotomy is particularly effective in children with MYOC JOAG, allowing them to avoid, or at least delay, the need for more invasive surgeries like trabeculectomy and tube shunt surgeries with over 4 years of follow-up. To date, this is the first genetically directed glaucoma surgery available.

Financial disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.