Use of Contact Lenses to Optimize OCT Scans of the Optic Nerve in Glaucoma Suspects or Patients with Glaucoma with High Myopia

Abstract

Patients with myopia are at increased risk for the development of glaucoma. The inability to correct for axial length on spectral-domain (SD) OCT translates into lower signal strength and scan reliability in patients with high axial myopia. We evaluated the effectiveness of a contact lens to increase the signal strength and to assess optic nerve dimensions and nerve fiber layer (NFL) thickness using SD OCT in patients with glaucoma or who are glaucoma suspects with high axial myopia. Single-center, prospective, interventional study. Patients with axial lengths of more than 25.5 mm with a diagnosis of glaucoma or glaucoma suspect. The optic nerve cube 200×200 scan using the Cirrus SD OCT 400 (Carl Zeiss Meditec, Inc., Dublin, CA) was carried out first without the use of a contact lens and then repeated with placement of the contact lens to correct for the spherical equivalent of the refractive error. The primary outcome measure was the change in the average NFL thickness before and after use of the contact lens. Secondary outcome measures included the changes in cup volume, disc area, and rim area on OCT. Twelve patients were recruited (20 eyes); the average axial length was 27.06 mm, and the average signal strength interval increased by 1.73 (P= 0.001). With the use of a contact lens, the average NFL thickness was significantly thicker. None of the changes in the secondary outcome measures were significant: rim area, cup volume, or disc area. Based on our data, the use of a contact lens statistically improved the signal strength and average NFL thickness of the SD OCT scan. The ability to capture the perimeter of the optic disc accurately can be limited in the setting of peripapillary atrophy, which was present in all but 2 participants. Future studies with a larger number of participants and a wider range of axial myopia to discern if contact lens correction has a greater effect on the highest axial lengths are needed.