Glaucoma and Myopia

Myopia (near-sightedness) is a significant risk factor for the development of glaucoma.^1,2 There are a number of reasons for this, not all of which are well understood. Furthermore many people with myopia have optic nerve heads with a ‘suspicious’ appearance which may look very much like what is seen in people that have optic nerve damage from glaucoma.³ 

Sometimes telling ‘glaucoma suspects’ apart from people who actually have glaucoma can be very challenging in people who are short-sighted. People who are short-sighted have approximately twice the risk of developing glaucoma as the general population².

People with myopia need regular eye examinations, including checking the optic nerve and the visual field, looking for signs of the development of glaucoma. As people with myopia require glasses and contact lenses, they are often in contact with eyecare professionals in any case. However sometimes it can be extremely difficult to determine glaucomatous change from other changes in the eye associated with myopia, even with modern ancillary testing such as OCT.³ 

Eyes that are myopic, or short sighted, tend to be larger than average in size. This makes the optic nerve at the back of the eye more vulnerable to changes in the intraocular pressure. Many short sighted people with glaucoma tend to have so called ‘normal tension’ glaucoma where the intraocular pressure is not particularly elevated - it is thought that weakness of the optic nerve as it enters the back of the eye is why there can be glaucomatous damage at relatively low pressures (3). There is also a theory that during eye movement the optic nerve is stretched more in people with larger eyeballs, and this can give rise to glaucoma.⁴

Managing glaucoma in patients with myopia is similar to managing glaucoma in other people but can be more challenging. When the pressure is already relatively low to start with it can be difficult to lower the pressure further with standard treatments. Furthermore surgical management in myopic eyes is challenging – these eyes are anatomically larger and respond to surgery slightly differently, and do not tolerate low pressures (hypotony) well. 

As the incidence of myopia is increasing dramatically in the developed world, the number of cases of glaucoma associated with this will increase too. Attempts to understand the mechanism for the development and progression of myopia with the hope to develop effective interventions are very important, in addition to checking people with myopia to diagnose glaucoma early if it occurs. 

References

1. Jonas, JB, Wang YX, Dong L, Panda-Jonas S. High Myopia and Glaucoma-like Optic Neuropathy. APJO 2020;9:234-238.

2. Marcus MW, de Vries MM, Junoy Montolio FG, Jansonius NM. Myopia as a risk factor for Open-angle Glaucoma: A Systematic Review and Meta-Analysis. Ophthalmology 2011;118:1989-1994.

3. Tan NYQT, Sng CCA, Jonas JB, Wong TY, Jansonius NM, Ang M. Glaucoma in Myopia: diagnostic dilemmas. BJO 2019;103:1347-1355.

4. Demer JL, Clark RA, Suh SY, Gianconi JA, Nouri-Mahdavi K, Law SK, Bonelli L, Coleman AL, Caprioli J. Magnetic resonance imaging of optic nerve traction during adduction in primary open-angle glaucoma with normal intraocular pressure. Invest Ophthalmol Vis Sci. 2017;58:4114-4125.