Glaucoma Screening and Prevention

 

Our eyes are one of the most important organs of our body. Amongst the five senses, being able to see things is a primary capacity to carry out our regular activities. It is, therefore, important to be able to know how to lessen our risk of acquiring one of the leading causes of irreversible blindness globally.

 

 

What is Glaucoma?

Glaucoma is a relatively common condition that affects the eyes. This disease involves pathologic loss of retinal ganglionic cells (nerve cells within the inner surface of the retina responsible for receiving visual information), which leads to progressive loss of vision.1

 

The mechanism of damage to the optic nerve cells and eventual loss involves interplay of interconnecting complex factors which is not fully understood. However, cells in the retina are often damage by an increase in intraocular pressure (IOL) which is the result of a build-up of fluid, known as aqueous humor.2 Aqueous humor flows between the anterior and posterior chambers of the eye. It serves as conduit for transport of nutrients to surrounding tissues inside the eye and protects ocular tissues from disease-causing pathogens by the natural antibodies called immonoglobulins that are present in the fluid.

 

Fluid build-up occurs primarily in two ways: by increase in production of fluid by the ciliary body (part of the eye that produces aqueous humor) or by an obstruction of the normal flow of the drainage system. The latter is mainly encountered in the two primary types of glaucoma, namely, angle-closure glaucoma and primary open-angle glaucoma. The difference lies in the drainage angle formed between the iris and the cornea where aqueous humor flows outwardly. Angle-closure glaucoma as the name suggests has the drainage angle obstructed due to the iris bulging forward which leads to a narrow or blocked drainage system. On the other hand, primary open-angle glaucoma is mainly due to the reduced drainage of aqueous fluid into the system resulting into backflow of the fluid into the eye that leads to increased intraocular pressure.

 

Risk Factors for Developing Glaucoma

Figure 1 shows the relevant risk factors for developing glaucoma. Non-modifiable risk factors include advancing age, family history and genetic predisposition, ethnic origin and myopia.3,4 On the other hand, risk factors such as smoking, steroid use, traumatic injuries to the eye and frequency of eye examinations are modifiable, which enables individuals to lessen their risk of developing glaucoma.3,4

 

Figure1. Risk factors associated with glaucoma

 

Individuals who have diabetes5,10 and hypertension6,7 may also be at higher risk of developing glaucoma. Although other studies8,9 have shown contrasting association between these conditions and glaucoma, it is beneficial in general to have acceptable blood sugar levels and controlled blood pressure amongst individuals with these chronic conditions.

 

Prevention and Screening of Glaucoma

Due to the risk of irreversible loss of vision, prevention and screening is highly important in glaucoma. Prevention strategies that can modify an individualís risk rely on factors that are modifiable.

 

Tobacco smokers are exposed to various hazardous compounds that result in numerous health conditions including eye disorders. In general, smoking cessation amongst users reduces these risks and may particularly delay or lessen the risk for glaucoma development. Glaucoma risk may be reduced by decreasing central corneal thickness11, a pathology that is often implicated in the mechanism of developing glaucoma as it affects intraocular pressure. Although modest increases in IOP were noted amongst smokers in the Blue Mountains Eye Study6, the effect of smoking cessation has an overall improvement on the health of the user.

 

Long-term use of steroids and eye injury are both risk factors associated with moderate risk of developing glaucoma3,4. It is, therefore, highly advised that frequency of steroid use needs to be under the supervision medical practitioners. Preventive measures such as the use of goggles or other protective eye gears during activities which may result in traumatic injury to the eye is vital.

Those with chronic systemic conditions, especially diabetics and hypertensive patients, need to regularly consult with their medical providers to prevent further complications and be screened regularly for glaucoma development. It is important that annual ocular checks by eye care providers are done amongst these patients.

 

Other relevant preventive strategies that may help prevent glaucoma, which are still controversial include physical activity, moderate intake of alcohol and dietary modification.12,13 Although, evidences have shown conflicting results, these lifestyle changes are generally imperative to ones health. The benefits of these strategies encompass not just glaucoma prevention but other medical conditions that may put an individual at risk, if lifestyle changes are not put in place.

 

Universal screening for glaucoma is currently not advised. However, targeted screening amongst patients who are at increased risk of developing glaucoma is presently accepted and highly advised. Patients who are at higher risk need to be regularly checked and examined for signs of glaucoma. It is important that when increased intraocular pressure is detected amongst these individuals, pharmaceutical agents that reduce this pressure is given to slow or prevent the development of glaucoma.1,3

 

Latest breakthrough

A new handheld ultrahigh speed ophthalmic instrument with scanning mirror has been completed by a team of researchers at the Massachusetts Institute of Technology in the USA.14 This handheld technology should be able to provide early detection of retinal diseases before irreversible damage is done leading to loss of visual perception. It may also aid in screening at-risk patients which may eventually result in early treatment and management. Besides these, it will also serve as an important technological tool that promises to be utilised outside of the traditional ophthalmic or optometric clinics.

 

 

References:

  1. Beidoe G, Mousa SA. Current primary open-angle glaucoma treatments and future directions. Clinical Ophthalmology. 2012. 6:1699-1707.
  2. Rieck J. The pathogenesis of glaucoma in the interplay of the immune system. Investigative Ophthalmology &Visual Science. 2013. 54(3):2393-2409.
  3. National Health and Medical Research Council. Guidelines for the screening, prognosis, diagnosis, management and prevention of glaucoma. Canberra. NHRMC.2010.
  4. Worley A, Grimmer-Somers K. Risk factors for glaucoma: What do they really mean? Australian Journal of Primary Health. 2011. 17(3):233-239.
  5. Bonovas S, Peponis V, Filioussi K. diabetes mellitus as a risk factor for primary open-angle glaucoma: A meta-analysis. Diabetic Medicine. 2004. 21(6):609-614.
  6. Mitchell P, Lee AJ, Rochtchina E, Wang JJ. Open-angle glaucoma and systematic hypertension: the Blue Mountains eye study. Journal of Glaucoma. 2004. 13:319-326.
  7. Memarzadeh F, Ying-Lai M, Chung J, Azen SP, Varma R. Blood pressure, perfusion pressure and open-angle glaucoma: The Los Angeles Latino eye study. Investigative Ophthalmology & Visual Science. 2010. 51(6):2872-2877.
  8. de Voogd S, Ikram Mk, Wolfs RC, Jansonius NM, Witteman JC, Hofman A, de Jong PT. Is diabetes mellitus a risk factor for open-angle glaucoma? The Rotterdam study. Ophthalmology. 2006. 113(10):1827-1831.
  9. Leske MC, Wu SY, Hennis A, Honkanen R, Nemesure B, Risk factors for incident open-angle glaucoma. The Barbados eye studies. Ophthalmology. 2008. 115(1):85-93.
  10. Welinder LG, Riis AH, Knudsen LL, Thomsen RW. Diabetes, glycemic control and risk of medical glaucoma treatment: a population-based case-control study. Clinical Epidemiology. 2009. 1:125-131.
  11. Wang D, Huang Y, Huang C, Wu P, Lin J, Zheng Y, Peng Y, Liang Y Chen J-H, Zhang M. Association analysis of cigarette smoking with onset of primary open-angle glaucoma and glaucoma-related biometric parameters. BMC Ophthalmology. 2012. 12:59.
  12. Pasquale LR, Kang JH. Lifestyle, nutrition and glaucoma. Journal of Glaucoma. 2009. 18 (6):423-428.
  13. Yip J, Broadway DC, Luben R, Garway-Heath DF, Hayat S, Dalzell N, Lee PS, Bhaniani A, Wareham NJ, Khaw K-T, Foster PJ. Physical activity and ocular perfusion pressure: The EPIC-Norfolk eye study. Investigative Ophthalmology & Visual Science. 2011. 52(11):8186-8192.
  14. Lu CD, Kraus MF, Potsaid B, Liu JJ, Choi WJ, JayaramanV, Cable AE, Hornegger J, Duker JS, Fujimoto JG. Handheld ultrahigh speed swept source optical coherence tomography instrument using a MEMS scanning mirror. Biomedical Optics Express. 2014. 5 (1):293-311.