By Jenna Greenfield MD

Cataracts are the most common cause of blindness worldwide (1).  Cataracts are a degenerative disease of aging, with the prevalence increasing exponentially with age.  In the United States, 17% of people over age 40 have cataracts.  By age 75, half of white Americans, and by 80, 70% of white Americans have cataracts (slightly less in blacks and hispanics) (2). 

What Are Cataracts?

A cataract is the clouding of the lens of the eye.  The lens is the transparent structure in the anterior of the eye that allows light to pass through to the retina.  In order to be transparent, the organelles in the cells of the lens are eliminated during differentiation, and because of this the cells in the center of the lens cannot produce new proteins.  The crystallin proteins are lens proteins that must maintain their precise structure as to not refract light that enters the lens, and maintain transparency.  They are relatively long lived and stable proteins, but over time all proteins suffer damage, due to oxidative stress and aging.  When damage to the crystallin proteins accumulates, the proteins unfold, and form protein aggregates, which refract light and cause clouding of the lens.  (3-5)

Cataracts in Iron Workers

Near infrared has long been known to promote cataract formation with high or repeated exposure.  Iron, steel, and glass workers are occupationally exposed to high levels of near infrared.  This was examined in a large study on ironworkers in 1984.  Iron workers were found to have 2.5 times the risk of cataracts compared to controls, and the risk of needing cataract surgery was 12 times that of non-exposed controls.  (6) 

Animal Studies

Many animal studies have since confirmed this (7,8).  Near infrared exposure causes damage to the crystallin proteins in the lens, making them less soluble and prone to aggregation.  When rabbits were exposed to near infrared light at 0.2 W/cm2 for just 5 to 10 seconds, the soluble protein content of their lens decreased in a dose dependent manner.  Soluble lens protein dropped from 290 mg/g, to 245 mg/g one hour after 5 minutes of NIR exposure, and to 209 mg/g after 10 minutes of exposure. (7).  

Infrared Wavelengths

Infrared is a wide band of light, with wavelengths from 780nm (just beyond the visible spectrum) to 1mm.  Near infrared, or IR-A, are the shortest wavelengths, between 780nm to 1400nm.  Mid infrared, IR-B, are wavelengths from 1400 to 3000nm, and far infrared, IR-C, are the longest wavelengths, greater than 3000nm.   Wavelengths in the far infrared spectrum have never been shown to cause damage to the eye, and within the near infrared spectrum, it has been shown that ocular damage is inversely correlated to wavelength, with shorter wavelengths causing more damage than longer wavelengths (9). 

ICNIRP Guidelines

According to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) statement, the IR energy from IR-A and IR-B poses a risk to the human eye.  The ICNIRP commission recommends “that to avoid thermal injury of the cornea and the possible cataractogenesis (cataract formation), IR-A and/or  IR-B exposure should be limited to 10 mW/cm2 for lengthy exposures (> 1000 seconds), and to 1.8 t–3/4 W/cm2 for shorter exposure durations.” (10)

While animal studies have been able to determine thresholds for acute exposure causing immediate cataract formation, there is little data on safe levels of long-term exposure, and therefore thresholds for long term repeated exposure have not been established.  The ICNIRP acknowledges that “cataract has been epidemiologically associated with chronic intermittent exposure at low irradiance.” (11)

Near Infrared Eye Protection

It is so well accepted that near infrared is damaging to the eyes, that near infrared protective glasses are sold for use in near infrared saunas.  If you own a near infrared sauna, and it is not a possibility for you to replace it at this time, it would be prudent to wear eye protection while in your sauna.  However, if you are researching a future sauna purchase, we strongly recommend staying away from damaging near infrared.  In addition to eye damage, near infrared has been shown to cause oxidative damage, skin aging and there are studies even suggesting it may promote skin cancer.  Read more about the risks of near infrared here.

High Tech Health Far Infrared Saunas

High Tech Health has done the research on the risks of near infrared, as we do on every aspect of the health effects of our saunas, and our Transcend saunas are far infrared only.  Read more about our lowest-emf far infrared saunas here.


  1. Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis. Flaxman SR, Bourne RRA, Resnikoff S, Ackland P, Braithwaite T, Cicinelli MV, Das A, Jonas JB, Keeffe J, Kempen JH, Leasher J, Limburg H, Naidoo K, Pesudovs K, Silvester A, Stevens GA, Tahhan N, Wong TY, Taylor HR; Vision Loss Expert Group of the Global Burden of Disease Study. Lancet Glob Health. 2017 Dec;5(12):e1221-e1234
  3. Biological glass: structural determinants of eye lens transparency. Bassnett S, Shi Y, Vrensen GF. Philos Trans R Soc Lond B Biol Sci. 2011 Apr 27;366(1568):1250-64
  4. The etiology of human age-related cataract. Proteins don’t last forever. Truscott RJ, Friedrich MG. Biochim Biophys Acta. 2016 Jan;1860(1 Pt B):192-8
  5. Lens β-crystallins: the role of deamidation and related modifications in aging and cataract. Lampi KJ, Wilmarth PA, Murray MR, David LL. Prog Biophys Mol Biol. 2014 Jul;115(1):21-31
  6. Infrared radiation and cataract. Lydahl E. Acta Ophthalmol Suppl. 1984;166:1-63
  7. Effect of infrared radiation on the lens. Aly EM, Mohamed ES. Indian J Ophthalmol. 2011 Mar-Apr;59(2):97-101
  8. Determination of infrared radiation levels for acute ocular cataractogenesis. Pitts DG, Cullen AP. Albrecht Von Graefes Arch Klin Exp Ophthalmol. 1981;217(4):285-97
  9. Trends in retinal damage thresholds from 100-millisecond near-infrared laser radiation exposures: a study at 1,110, 1,130, 1,150, and 1,319 nm. Vincelette RL, Rockwell BA, Oliver JW, Kumru SS, Thomas RJ, Schuster KJ, Noojin GD, Shingledecker AD, Stolarski DJ, Welch AJ.
  10. 10.Guidelines on limits of exposure to broad-band incoherent optical radiation (0.38 to 3 microM). International Commission on Non-Ionizing Radiation Protection. [No authors listed] Health Phys. 1997 Sep;73(3):539-54
  11. 11.ICNIRP Guidelines on Limits of Exposure to Incoherent Visible and Infrared Radiation: Errata. Health Physics: April 2014 – Volume 106 – Issue 4 – p 530–531
  12. 12.