Open angle glaucoma

It is characterized by a progressive degeneration of the optic nerve, usually accompanied by an increase in intraocular pressure. It is the second leading cause of irreversible blindness in the world, with an estimated overall prevalence of about 2.4%. Its detection in early stages is important to delay or prevent vision loss, since once it occurs it cannot be recovered.

In open-angle glaucoma, as its name indicates, the drainage angle of the intraocular aqueous humor formed by the cornea and the iris remains open, but the drainage system is partially blocked, which causes the ocular pressure to gradually increase and the optic nerve to be damaged. In addition to family history, the following factors would condition an increased risk of developing open-angle glaucoma:

  • Presenting a previous disorder of elevated intraocular pressure.
  • Age: the risk increases with age, especially after 60 years of age.
  • African-American, Asian or Hispanic ancestry has been associated with an increased risk of glaucoma.
  • Certain diseases such as diabetes, heart disease or high blood pressure.
  • Particular eye characteristics such as thin corneas in the center,
  • Eye diseases such as extreme nearsightedness or farsightedness, history of previous eye injury or certain types of eye surgery.
  • Corticosteroid medications over a long period of time, especially eye drops.

Research to date has shown its multifactorial nature, with a strong heritable component but wide variability between individuals and ethnicities, estimating a very broad genetic contribution of 20-80% depending on the phenotype and population studied, suggesting an incomplete genetic picture. A recent meta-analysis in 380000 controls and 34000 cases has allowed the identification of 63 significant loci broadly consistent in different ancestries, which would contribute to the pathogenesis of glaucoma through the genetic background.A recent meta-analysis in 380000 controls and 34000 cases has identified 63 significant loci broadly consistent in different ancestries, which would contribute to the pathogenesis of glaucoma through mechanisms related to cell adhesion, intracellular chloride channels, adipose metabolism and signaling control of organ size and development.

Symptoms

In the initial stages it is not associated with symptoms, does not cause pain and vision remains normal. However, if left untreated, progressive loss of lateral or peripheral vision begins in the form of irregular blind spots. Over time, as the pathology progresses, central (forward) vision will also be affected in the form of tunnel vision, decreasing until it is completely lost. This may affect one or both eyes. Intraocular pressure may be normal or high, but it is almost always higher in the eye with the more advanced optic nerve lesion.

Prevention

Early detection of glaucoma can prevent vision loss or slow the rate of progression. Therefore, the following guidelines are recommended:

  • Visit an ophthalmologist from the age of 40 at least once a year to control intraocular pressure and perform a detailed examination of the optic nerve.
  • Regular, moderate physical activity can reduce eye pressure and help prevent glaucoma.
  • Use appropriate eye protection when required in both occupational and leisure settings. Severe eye injuries can promote the development of glaucoma.

Number of observed variants

13.5 million variants

Number of risk loci analyzed in the study

63 loci

Bibliography

Zhang N et al.Prevalence of primary open angle glaucoma in the last 20 years: a meta-analysis and systematic review. Sci Rep 2021; 11, 13762.

National Institute of Health. National Eye Institute [April 2022]

Glaucoma Research Foundation [April 2022]

Mayo Clinic [April 2022]

Gharahkhani P et al. Genome-wide meta-analysis identifies 127 open-angle glaucoma loci with consistent effect across ancestries. Nature Communications. 2021 Feb;12(1):1258.

The DNA test you were looking for