Dealing with a Double Whammy

that excluding deep retinal layer S-F associations may help to increase the diagnostic accuracy of high myopiaglaucoma.

Optic neuropathy in high myopia

by Tan Sher Lynn

Experts share insights into the diagnosis and treatment of myopia-associated glaucoma

Glaucoma can cause vision loss by damaging the optic nerve. According to Dr. Jost Jonas (Germany), risk factors for glaucomatous or glaucoma-like optic nerve damage in highly myopic eyes include a larger parapapillary delta zone, larger optic disc, and older age. However, the potential role of intraocular pressure (IOP) is still unclear.

On the other hand, he noted that nonglaucomatous optic nerve damage is perhaps due to the elongation of axons, longer axial length, and wider parapapillary gamma zone. He suggested that all highly myopic eyes should be considered to have optic nerve damage until the contrary has been proven in individual patients.

Accurate diagnosis and appropriate management of glaucoma in highly myopic eyes remain a challenge. On Day 1 of the 35th Asia-Pacific Association of Cataract and Refractive Surgeons (APACRS 2023) annual meeting, experts shared their thoughts on tackling the high myopia-glaucoma issue

First up was Dr. Wong Chee Wai (Singapore), who talked about imaging the highly myopic eye. According to Dr. Wong, both functional and anatomical assessment can be confounded in highly myopic eyes. As such, careful and detailed evaluation with multimodal imaging is necessary to properly assess these eyes.

He noted that visual field abnormalities can arise from myopic traction maculopathy (MTM) and various lesions in myopic macular degeneration (MMD), while thinning or thickening of the inner retinal layers can arise from MTM or previous macula-off retinal detachment. In addition, the use of microperimetry may improve structure-function (S-F) correlation.

“As always, longitudinal analysis is key for assessing both glaucoma and myopic maculopathy. By comparing the same eye over time, the impact of ambiguous anatomy on diagnosis and monitoring will be reduced,” he said.

Structure-function associations in diagnosis

Next, Dr. Rachel Chong (Singapore) explored the question of how to improve high myopia-glaucoma diagnosis using the S-F relationship.

According to Dr. Chong, myopia alters chorioretinal layer thickness and retinal topography, and is associated with visual field defects. In her study, she found that in high myopia-glaucoma patients, the superficial retinal ganglion cell (RCG) layers show the strongest S-F associations with visual field sensitivity.

Meanwhile, in high myopia-glaucoma suspects, both superficial and deep retinal layer thickness measurements are associated with visual field sensitivity. Therefore, she concluded

Surgical management of glaucoma in myopic eyes

Meanwhile, Dr. Ho Ching Lin (Singapore) noted that since there are no clear surgical algorithms for glaucoma in high myopia currently, there is a need to treat each patient differently, as each has a different cause and progression risk.

“We need to monitor closely for the location of defect, progression rate, and relation to IOP changes. Document definite progression — not just indepth defects but also new areas before escalating treatment,” she said. “Also, exercise caution in performing glaucoma surgery in myopic eyes. Always lean towards safety in very elongated eyes with staphyloma and significant retina-choroidal changes.”

Dr. Ho also suggested avoiding augmented filtration surgery. “Noninvasive options such as medicines, laser trabeculoplasty, and safer surgical options should be considered first before opting for conventional filtration surgery whenever possible,” she concluded.