Almost 50 years since inventing the Non-Contact Tonometer, Reichert® continues to innovate and pioneer patented non-contact technologies like Corneal Compensated IOP (IOPcc), a better pressure measurement, and Corneal Hysteresis (CH), a measurement consistently shown to be a more powerful predictor of, and strongly associated with, glaucoma progression, more so than key risk factors such as IOP and CCT.A-C
Now more than ever, eye care professionals are concerned about safety, not just for their patients but also for their staff. There has been much debate on the safest way to perform routine eye exams, especially when it comes to tonometry. Reichert is here to answer your questions on the safe use of Non-Contact Tonometers, and provide up-to-date information on best practices to follow.
According to the current research, there is no material evidence that Non-Contact Tonometry is an aerosol generating procedure, and the current science shows the risk of spreading COVID-19 through tears is low and seems to be confined to patients who present with ocular symptoms.
What level of cleaning is required for a Reichert Non-Contact Tonometer?
All Reichert Non-Contact Tonometers are classified as non-critical devices because they contact intact skin, they do not contact the mucous membrane. As such, Non-Contact Tonometers require low-level disinfection.
Note: Goldmann tonometers and prisms are classified as semi-critical and require high level disinfection.
What is the proper cleaning and low-level disinfection procedure for a Non-Contact Tonometer?
|INSTRUMENT PART||FREQUENCY||CLEANING & DISINFECTION PROCEDURE|
|Forehead Rest and Front Bezel||After Each Patient||
The forehead rest and the surrounding front bezel plastics may be cleaned with a clean cloth moistened with a mild detergent solution (1 cc of liquid dish soap to one liter of clean, filtered water [filtered below 5 microns]) or a sterile 70% isopropyl or ethanol alcohol wipe.
Note: Depending on model and serial number, replacement forehead rest pads can be purchased through your Authorized Reichert Distributor.
|External Surfaces||As Necessary||Clean the external surfaces of the instrument using a soft cloth moistened with a mild detergent solution (1 cc of liquid dish soap to one liter of clean, filtered water [filtered below 5 microns]).
|Operator Display||As Necessary||Clean the operator display of the instrument using a soft cloth moistened with a mild detergent, or a sterile 70% isopropyl or ethanol alcohol wipe.
|Optical Windows and Air Tube||As Necessary||Regular cleaning of the alignment and applanation optical windows is required. The air tube should also be cleaned at regular intervals. Do not use fluids to clean the air tube. Consult the user manual or contact Reichert Technical Support for instructions specific to your instrument.
Is there a risk of air tube contamination that can spread infections to other patients?
There is no evidence to suggest that contamination can enter the Non-Contact Tonometers air tube and cause harm to other patients.1
Is Non-Contact Tonometry an aerosol generating procedure (AGP)?
There is no material evidence that Non-Contact Tonometry is an aerosol generating procedure. The only publication on this subject is from 1991 by Britt et al. The authors used fluorescence photography to capture visible tear film splatter from the air puff in eyes with the application of supplemental topical fluorescein or artificial tears.1 However, this photographic method is not capable of capturing “aerosolization” as aerosols are particles that are not visible to the eye. Today, it is agreed that the authors used incorrect terminology in describing their findings as “micro-aerosolization”. It should also be noted that the air pulse technology utilized in the study applied 4 to 6 times more force than modern Non-Contact Tonometers, making the tear film splatter much more substantial.2
The applied air pulse force on the current Reichert Non-Contact Tonometers is up to 6 times softer than previous generations.
Is the SARS-CoV-2 virus present in tears?
The primary path of infection is through droplets produced by and entering into the mouth, nose, and lungs.3 Numerous studies evaluated the presence of SARS-CoV-2 in tears and found the risk to be low (0-5.2%) and only present in patients with ocular manifestations such as chemosis, conjunctival hyperemia, or conjunctivitis.4-6
What are the risks of spreading the virus through the eye?
It has been suggested that the eyes might be a portal of entry for the virus because of the presence of ACE receptors, but there is currently no clinical evidence for this theory (and the dermis also contains ACE receptors).7 In addition, there is no evidence that viral particles can be implanted into the eye during Non-Contact Tonometry. The air pulse generating mechanism in Reichert Non-Contact Tonometers is almost completely shielded by the plastic housing of the instrument, making it unlikely for respiratory droplets from patients or clinicians to enter the device.
Is there any evidence of infection spread by use of a Non-Contact Tonometer?
No, the Non-Contact Tonometer has a 50-year record of safety. There are no documented instances of infection being spread by use of a Non-Contact Tonometer.
Does Non-Contact Tonometry provide a safer working distance between clinician and patient, compared to other forms of tonometry?
Yes, the typical clinician-patient distance is approximately 3 feet and rarely requires the clinician to touch the eyelid.
Click here to download a printable PDF of Questions and Answers on Reichert Non-Contact Tonometer Safety in the COVID-19 Era.
Recent articles covering COVID-19 and Non-Contact Tonometer safety:
"Tonometry and Tonometer Disinfection in the COVID-19 Era."
|"Review of Hygiene and Disinfection Recommendations for Outpatient Glaucoma Care"
By Julie Shabto, BA, Carlos Gustavo De Moraes, MD, MPH, PhD, George Cioffi, MD, and Jeffrey M. Liebmann, MD
Journal of Glaucoma, June 2020
"...[Non-Contact Tonometers] permit more staff-patient distancing than other methods."
Read the full PDF article »
"Coronavirus disease 2019 (SARS-CoV-2) and colonization of ocular tissues and secretions: a systematic review"
A - Medeiros FA, Meira-Freitas D, Lisboa R, Kuang TM, Zangwill LM, Weinreb RN. Corneal hysteresis as a risk factor for glaucoma progression: a prospective longitudinal study. Ophthalmology. 2013 Aug;120(8):1533-40.
B - De Moraes CV, Hill V, Tello C, Liebmann JM, Ritch R. Lower corneal hysteresis is associated with more rapid glaucomatous visual field progression. J Glaucoma. 2012 Apr-May;21(4):209-13.
C - Susanna CN, Diniz-Filho A, Daga FB, Susanna BN, Zhu F, Ogata NG, Medeiros FA. Am J Ophthalmol. A Prospective Longitudinal Study to Investigate Corneal Hysteresis as a Risk Factor for Predicting Development of Glaucoma. 2018 Mar;187:148-152. doi: 10.1016/j.ajo.2017.12.018.
1 - Britt JM, Clifton BC, Barnebey HS, Mills RP. Microaerosol formation in noncontact 'air-puff' tonometry. Arch Ophthalmol. 1991 Feb;109(2):225-8. PubMed PMID: 1993032.
2 - Micalla Peng, MS; Nathan M. Radcliffe, MD. Ophthalmology Management, Volume: 24, Issue: Glaucoma Physician June 2020, page(s): E4-E7.
3 - Carlos WG, Dela Cruz CS, Cao B, Pasnick S, Jamil S. Novel Wuhan (2019-nCoV) Coronavirus. Am J Respir Crit Care Med. 2020 Feb 15;201(4):P7-P8. doi: 10.1164/rccm.2014P7. PubMed PMID: 32004066.
4 - Evaluation of coronavirus in tears and conjunctival secretions of patients with SARS CoV 2 infection. Jianhua Xia MM, Jianping Tong MD, Mengyun Liu MM, Ye Shen MD, Dongyu Guo MD. J Med Virol. 2020;16.
5 - Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med. 2020 Feb 28. doi: 10.1056/NEJMoa2002032. Guan WJ et al.
6 - Seah IYJ, Anderson DE, Kang AEZ, Wang L, Rao P, Young BE, Lye DC, Agrawal R. Assessing Viral Shedding and Infectivity of Tears in Coronavirus Disease 2019 (COVID-19) Patients. Ophthalmology. 2020 Mar 24. pii: S0161-6420(20)30311-0. doi: 10.1016/j.ophtha.2020.03.026.
7 - Zhou L, Xu Z, Castiglione GM, Soiberman US, Eberhart CG, Duh EJ. ACE2 and TMPRSS2 are expressed on the human ocular surface, suggesting susceptibility to SARS-CoV-2 infection. BioRXiv. https://doi.org/10.1101/2020.05.09.086165Â [submitted, not peer reviewed]
About Reichert Technologies®
Reichert Technologies®, based out of Buffalo, New York, is a global leader in designing, engineering, and manufacturing high-quality diagnostic devices and equipment for ophthalmologists, optometrists, opticians, and retail eye centers.
Inventor of Phoroptor®, Lensometer®, and the Non-Contact Tonometer, Reichert continues a 180 year tradition of providing American innovation with the digital Phoroptor® VRx, Tono-Pen® Tonometer, ClearChart® Digital Acuity Systems, and Ocular Response Analyzer®, a break-through in glaucoma diagnosis and management, featuring Corneal Hysteresis and IOPcc.
Reichert Technologies® is a business unit of the Ultra Precision Technologies Division of AMETEK, Inc. a leading global manufacturer of electronic instruments and electromechanical devices with annual sales of approximately $5 billion.