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Editors Selection IGR 12-1

Clinical Forms of Glaucoma: Glaucoma progression in myopic eyes

Comment by Shan Lin & Marissé Masís on:

60495 Effect of myopia on the progression of primary open-angle glaucoma, Lee JY; Sung KR; Han S et al., Investigative Ophthalmology and Visual Science, 2015; 56: 1775-1781

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The authors of this retrospective study describe the role of myopia in glaucoma progression in a Korean population. A total of 369 eyes were classified into non-myopic, mild to moderate (0 to -6 diopters) and highly myopic (< -6 diopters) according to the level of spherical equivalent.

To determine progression they used optic disc and red-free RNFL photographs, Cirrus HD OCT optic nerve analysis and serial Humphrey visual field data. After performing univariate and multivariate Cox proportional hazard models they concluded that no levels of myopia were associated with glaucoma progression and that high myopia might be a protective factor for optic disc/RNFL progression.

The clinical diagnosis in patients with myopia is often difficult; bigger optic disc size, tilting and peripapillary atrophy are some of the findings that could overlap with glaucoma features in a myopic eye. The follow-up of the myopic patient is a challenge as well, since the most commonly used structural parameters are often altered because of the abnormal anatomic findings and the progression analyses are usually based on normal subject databases. Also visual field defects have been previously described in myopic subjects without glaucoma. All of these factors make the documentation of progression even more difficult.¹

Evidence suggests that highly myopic eyes are different in structure from non-myopic or mildly myopic eyes, and may be at higher risk for glaucomatous damage and progression of VF loss in POAG patients.²

In 2008, a retrospective study of a Taiwanese population that included 515 eyes concluded that after five years of follow up, POAG patients with myopia greater than -6 D had greater progression of VF loss.³

Whether myopic eyes are more susceptible to glaucomatous damage is still debatable. As the authors suggest, a possible interpretation for the results could be that a lower progression detection rate was found when using the structural criteria or due mistaken glaucoma diagnosis secondary to the optic nerve characteristics.

Further prospective studies, with standardized progression criteria and including the axial length as a confounding factor in the statistical analysis are needed to validate high myopia as a protective factor for glaucoma progression.

Nonetheless, this article opens an interesting discussion about the role of myopia in glaucoma that may lead to new research avenues.

The follow-up of the myopic patient is a challenge since the most commonly used structural parameters are often altered because of the abnormal anatomic findings and the progression analyses are usually based on normal subject databases.

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