Guidance for Industry and FDA Staff 
 
Tonometers - Premarket 
Notification [510(k)] Submissions 
 
 
Document issued on: March 27, 2006 
 
For questions regarding this document, contact Everette Beers, Ph.D. at 240-276-4200 or via email at 
everette.beers@fda.hhs.gov. 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Devices and Radiological Health 
 
Diagnostic and Surgical Devices Branch 
Division of Ophthalmic and Ear, Nose and Throat Devices 
Office of Device Evaluation 
 
  Contains Nonbinding Recommendations 
 
Preface 
 
Public Comment 
Written comments and suggestions may be submitted at any time for Agency consideration to the  
Division of Dockets Management, Food and Drug Administration, 5630 Fishers Lane, Room 1061, 
(HFA-305), Rockville, MD, 20852.  When submitting comments, please refer to the exact title of 
this guidance document.  Comments may not be acted upon by the Agency until the document is 
next revised or updated. 
 
Additional Copies 
Additional copies are available from the Internet at: 
http://www.fda.gov/cdrh/ODE/guidance/1593.html, or to receive this document by fax, call the 
CDRH Facts-On-Demand system at 800-899-0381 or 301-827-0111 from a touch-tone telephone.  
Press 1 to enter the system.  At the second voice prompt, press 1 to order a document.  Enter the 
document number (1593) followed by the pound sign (#).  Follow the remaining voice prompts to 
complete your request. 
 
 
  
  Contains Nonbinding Recommendations 
 
Table of Contents 
 
1.  Introduction ______________________________________________________________ 1 
The Least Burdensome Approach_____________________________________________________1 
2.  Background ______________________________________________________________ 2 
3.  The Content and Format of an Abbreviated 510(k) Submission_____________________ 2 
A.  Coversheet_____________________________________________________________________3 
B.  Proposed labeling _______________________________________________________________3 
C.  Summary report________________________________________________________________3 
4.  Scope____________________________________________________________________ 5 
5.  Device Description_________________________________________________________ 5 
A.  Principles of Operation_________________________________________________________5 
B.  Technical Specifications ________________________________________________________6 
6.  Risks to Health____________________________________________________________ 6 
7.  Bench Testing_____________________________________________________________ 7 
A.  Accuracy_____________________________________________________________________7 
B.  Repeatability__________________________________________________________________7 
C.  Additional Device Features______________________________________________________8 
D.  Devices Containing Software ____________________________________________________8 
8.  Clinical Performance (non-Goldmann-type Tonometers only)______________________ 8 
A.  Non-Goldmann-type Tonometers_________________________________________________8 
9.  Validation of Cleaning and Sterilization Methods_______________________________ 10 
10.  Biocompatibility________________________________________________________ 10 
11.  Electrical Safety and Electromagnetic Compatibility___________________________ 10 
12.  Labeling ______________________________________________________________ 11 
 
  
  Contains Nonbinding Recommendations 
 
Guidance for Industry and FDA Staff 
 
Tonometers - Premarket Notification [510(k)] 
Submissions 
 
This guidance represents the Food and Drug Administrations (FDA's) current thinking on 
this topic.  It does not create or confer any rights for or on any person and does not operate to 
bind FDA or the public.  You can use an alternative approach if the approach satisfies the 
requirements of the applicable statutes and regulations.  If you want to discuss an alternative 
approach, contact the FDA staff responsible for implementing this guidance.  If you cannot 
identify the appropriate FDA staff, call the appropriate number listed on the title page of this 
guidance.  
 
 
1.  Introduction 
FDA has developed this guidance document to assist industry in preparing premarket notification 
submissions for contact and non-contact tonometers.  The device is intended for measuring 
intraocular pressure (IOP). 
 
The Least Burdensome Approach 
The issues identified in this guidance document represent those that we believe need to be 
addressed before your device can be marketed.  In developing the guidance, we carefully 
considered the relevant statutory criteria for Agency decision-making.  We also considered the 
burden that may be incurred in your attempt to follow the guidance and address the issues we 
have identified.  We believe that we have considered the least burdensome approach to 
resolving the issues presented in the guidance document.  If, however, you believe that there 
is a less burdensome way to address the issues, you should follow the procedures outlined in 
the "A Suggested Approach to Resolving Least Burdensome Issues" document.  It is available 
on our Center web page at: http://www.fda.gov/cdrh/modact/leastburdensome.html
 
FDA's guidance documents, including this guidance, do not establish legally enforceable 
responsibilities.  Instead, guidances describe the Agency's current thinking on a topic and should 
be viewed only as recommendations, unless specific regulatory or statutory requirements are 
cited.  The use of the word should in Agency guidances means that something is suggested or 
recommended, but not required.  
 
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2.  Background 
A manufacturer who intends to market a device of this generic type should conform to the general 
controls of the Federal Food, Drug, and Cosmetic Act (the Act), including the premarket 
notification requirements described in 21 CFR 807 Subpart E, and obtain a substantial 
equivalence determination from FDA prior to marketing the device. (See also 21 CFR 807.81 and 
807.87.)  
 
This guidance document identifies the classification regulation and product codes for tonometers 
(refer to Section 4. Scope).  In addition, other sections of this guidance document provide 
additional information to manufacturers on addressing risks related to these devices in premarket 
notifications (510(k)s).  
 
This document supplements other FDA documents regarding the specific content requirements of 
a premarket notification submission.  You should also refer to 21 CFR 807.87 and "How to 
Prepare a 510(k) Submission" on FDA Device Advice at 
http://www.fda.gov/cdrh/devadvice/314.html. 
 
Under The New 510(k) Paradigm - Alternate Approaches to Demonstrating Substantial 
Equivalence in Premarket Notifications; Final Guidance, 
http://www.fda.gov/cdrh/ode/parad510.html, a manufacturer may submit a Traditional 510(k) or 
has the option of submitting either an Abbreviated 510(k) or a Special 510(k). FDA believes an 
Abbreviated 510(k) provides the least burdensome means of demonstrating substantial 
equivalence for a new device, particularly once FDA has issued a guidance document addressing 
that device. Manufacturers considering certain modifications to their own cleared devices may 
lessen the regulatory burden by submitting a Special 510(k). 
 
3.  The Content and Format of an Abbreviated 510(k) 
Submission  
An Abbreviated 510(k) submission must include the required elements identified in 21 CFR 
807.87, including the proposed labeling for the device sufficient to describe the device, its 
intended use, and the directions for its use.  In an Abbreviated 510(k), FDA may consider the 
contents of a summary report to be appropriate supporting data within the meaning of 21 CFR 
807.87(f) or (g); therefore, we recommend that you include a summary report.  The report should 
describe how this guidance document was used during the device development and testing and 
should briefly describe the methods or tests used and a summary of the test data or description of 
the acceptance criteria applied to address the risks identified in this document, as well as any 
additional risks specific to your device.  This section suggests information to fulfill some of the 
requirements of section 807.87 as well as some other items that we recommend you include in an 
Abbreviated 510(k). 
 
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A.  Coversheet 
The coversheet should prominently identify the submission as an Abbreviated 510(k) and cite 
the title of this guidance document. 
 
B.  Proposed labeling 
Proposed labeling should be sufficient to describe the device, its intended use, and the 
directions for its use.  (Please refer to Section 12.  Labeling for specific information that 
should be included in the labeling for devices of the type covered by this guidance document.) 
 
C.  Summary report 
We recommend that the summary report contain: 
 
Description of the device and its intended use   
We recommend that you describe the performance specifications and, when appropriate, 
include detailed, labeled drawings of the device.  Please refer to Section 5.  Device 
Description for specific information that we recommend you include in the device 
description for devices of the type covered by this guidance document.  You should also 
submit an indications for use enclosure.1   
 
Description of device design  
We recommend that you include a brief description of the device design requirements. 
 
Identification of the risk analysis method 
We recommend that you identify the risk analysis method(s) you used to assess the risk 
profile, in general, as well as the specific devices design and the results of this analysis.  
Please refer to Section 6.  Risks to Health for the risks to health generally associated with 
the use of this device that FDA has identified. 
 
Discussion of the device characteristics  
We recommend that you discuss the device characteristics that address the risks identified 
in this guidance document, as well as any additional risks identified in your risk analysis.  
 
Description of the performance aspects 
We recommend that you include a brief description of the test method(s) you have used or 
intend to use to address each performance aspect identified in Sections 7-11 of this 
guidance document.  If you follow a suggested test method, you may cite the method 
rather than describing it.  If you modify a suggested test method, you may cite the method 
                                                 
1 Refer to http://www.fda.gov/cdrh/ode/indicate.html for the recommended format. 
 
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but should provide sufficient information to explain the nature of and reason for the 
modification.  For each test, you may either (1) briefly present the data resulting from the 
test in clear and concise form, such as a table, or (2) describe the acceptance criteria that 
you will apply to your test results.2  (See also 21 CFR 820.30, Subpart C - Design 
Controls for the Quality System Regulation.) 
 
Reliance on standards 
If you choose to rely on a recognized standard for any part of the device design or testing, 
you may include either a:  
 
  statement that testing will be conducted and meet specified acceptance criteria 
before the device is marketed; or  
 
  declaration of conformity to the standard.3   
 
Because a declaration of conformity is based on results from testing, we believe you cannot 
properly submit a declaration of conformity until you have completed the testing the 
standard describes.  For more information, please refer to section 514(c)(1)(B) of the Act 
and the FDA guidance, Use of Standards in Substantial Equivalence Determinations; 
Final Guidance for Industry and FDA.4  
 
If it is not clear how you have addressed the risks identified by FDA or additional risks identified 
through your risk analysis, we may request additional information about aspects of the devices 
performance characteristics.  We may also request additional information if we need it to assess 
the adequacy of your acceptance criteria.  (Under 21 CFR 807.87(l), we may request any 
additional information that is necessary to reach a determination regarding substantial 
equivalence.)  
 
As an alternative to submitting an Abbreviated 510(k), you can submit a Traditional 510(k) that 
provides all of the information and data required under 21 CFR 807.87 and described in this 
guidance.  A Traditional 510(k) should include all of your methods, data, acceptance criteria, and 
conclusions.  Manufacturers considering certain modifications to their own cleared devices should 
consider submitting Special 510(k)s.  
 
                                                 
2 If FDA makes a substantial equivalence determination based on acceptance criteria, the subject 
device should be tested and shown to meet these acceptance criteria before being introduced into 
interstate commerce.  If the finished device does not meet the acceptance criteria and, thus, differs 
from the device described in the cleared 510(k), FDA recommends that submitters apply the same 
criteria used to assess modifications to legally marketed devices (21 CFR 807.81(a)(3)) to 
determine whether marketing of the finished device requires clearance of a new 510(k). 
3 See Required Elements for a Declaration of Conformity to a Recognized Standard 
(Screening Checklist for All Premarket Notification [510(K)] Submissions), 
http://www.fda.gov/cdrh/ode/reqrecstand.html. 
4 See http://www.fda.gov/cdrh/ode/guidance/1131.html
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The following is a specific discussion of how you should apply this guidance document to a 
premarket notification submission for a tonometer.  
 
4.  Scope 
The scope of this guidance document is limited to the device described below, 21 CFR 886.1930, 
product codes, HKY (Tonometer, Manual) and HKX (Tonometer, AC-Powered). 
 
 21 CFR 886.1930 Tonometer and accessories. 
A tonometer and accessories is a manual device intended to measure intraocular pressure by 
applying a known force on the globe of the eye and measuring the amount of indentation 
(Schiotz type) or to measure intraocular tension by applanation (applying a small flat disk to 
the cornea).  Accessories for the device may include a tonometer calibrator or a tonograph 
recording system.  The device is intended for use in the diagnosis of glaucoma. 
 
The generic type device includes other types of contact tonometers (e.g., strain gauge), as well as 
non-contact (i.e., air-puff) tonometers.  It also encompasses tonometers that adjust IOP based on 
other ocular parameters.  These technologies are within the scope of this guidance. 
 
5.  Device Description  
We recommend you identify your device by the regulation and product code described in Section 
4.  We recommend you provide a description of the principles of operation and the technical 
specifications as discussed below. 
A.  Principles of Operation 
 
1.  Measurement Method 
We recommend you describe the parameters used to measure IOP and any other quantities 
measured by the device, such as corneal mechanical properties and corneal geometry, if 
applicable. 
 
2.  Signal Processing 
We recommend that you provide the main signal processing and computational steps 
involved in converting a raw signal into an IOP reading and other quantities, if applicable. 
 
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3.  Calibration 
We recommend that you provide how the device is calibrated during production and how 
calibration is maintained over the life of the device. 
 
4.  Adjustments to IOP 
If the device adjusts measured IOP based on other ocular parameters (e.g., corneal 
thickness or mechanical properties), we recommend that you explain the scientific basis 
for these adjustments, including appropriate theoretical and empirical analyses (see 
Sections 7-8).  We also recommend that you submit any relevant literature references. 
 
B.  Technical Specifications 
In describing the technical specifications of your device, we recommend that you include: 
  measurement range 
  accuracy (e.g., 95% tolerance interval relative to manometry) and repeatability (e.g., 
coefficient of variation) 
  applanation area, contact area, or area of corneal deformation 
  type of pressure transducer (e.g., optical detector, strain gauge) and specifications 
  electrical specifications 
  data display and output type (e.g., numerical digital, computer screen, printout) 
  data storage capability (e.g., measurement results, patient information) 
  interface with other equipment (e.g., printer, computer network) 
  dimensions and weight. 
 
6.  Risks to Health 
In the table below, FDA has identified the risks to health generally associated with the use of the 
device addressed in this document.  The measures recommended to mitigate these identified risks 
are given in this guidance document, as shown in the table below.  We recommend that you also 
conduct a risk analysis, prior to submitting your 510(k), to identify any other risks specific to your 
device and submit the results of this analysis.  If you elect to use an alternative approach to 
address a particular risk identified in this document, or have identified risks additional to those in 
this document, then you should provide sufficient detail to support the approach you have used to 
address that risk. 
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Identified Risk  Recommended Mitigation Measures 
Inaccurate or unreliable  Section 7.  Bench Testing 
measurement and consequent 
Section 8.  Clinical Performance  
inappropriate therapy 
Section 12.  Labeling 
Infection  Section 9.  Validation of Cleaning and Sterilization 
Methods 
Tissue adverse reaction  Section 10.  Biocompatibility  
Electrical shock or  Section 11.  Electrical Safety and Electromagnetic 
electromagnetic interference  Compatibility 
 
 
7.  Bench Testing 
For all tonometers, we recommend that you provide accuracy and repeatability results for your 
device that span the nominal range of pressures your device is intended to measure.  This testing 
may be an element of a clinical study; or it may be accomplished through use of pressure-
controlled model, ex vivo animal, or human (eye bank) eyes.   
 
For any method used, we recommend that you describe its strengths and limitations.  We also 
recommend that you validate your baseline IOP during testing and verify that the act of repeated 
measurements does not significantly influence IOP.   
A.  Accuracy 
If you use pressure-controlled eyes (i.e., model, animal, or eye bank eyes) in your accuracy 
studies, we recommend that you conduct testing at the lower limit of the nominal pressure 
measurement range and every multiple of 10 mmHg, up to the upper limit.  For a device with 
a nominal range of 5 to 45 mmHg, for example, we recommend that you test at 5, 10, 20, 30, 
40, and 45 mmHg. 
 
B.  Repeatability 
We recommend that you conduct testing on a set of 3 (or more) eyes for each pressure value, 
with 10 measurements (i.e., normal clinical outputs) per eye.  Each eye should only be used at 
one pressure.   
 
We recommend that for each eye at each reference pressure, you report the mean measured 
IOP, standard deviation, and coefficient of variation.  Additionally, we recommend that you 
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report the overall accuracy and repeatability at each pressure as the average of the 3 (or more) 
mean measured IOP values and the average of the 3 (or more) coefficients of variation at that 
pressure. 
C.  Additional Device Features 
If the device contains any feature that adjusts the measured IOP based on other ocular 
parameters (e.g., corneal thickness or mechanical properties), we also recommend that you 
provide performance results to validate each feature. 
D.  Devices Containing Software 
If your device contains software, we recommend you provide the information appropriate to 
the level of concern for your device, as described in Guidance for the Content of 
Premarket Submissions for Software Contained in Medical Devices.5  
8. Clinical Performance (non-Goldmann-type Tonometers only)
A.  Non-Goldmann-type Tonometers 
In addition to the bench testing described above, for all non-Goldmann-type tonometers, we 
recommend that you compare your device with a calibrated Goldmann-type applanation 
tonometer in a statistically significant representative sample of human subjects eyes.   
1. Data Collection
We recommend that you follow the data collection aspects of the American National 
Standards Institute (ANSI) tonometer standard Z80.10-2003 or equivalent method.  
2. Calibration
We recommend that you describe the calibration method and provide calibration results 
for the reference Goldmann-type tonometer. 
3. Sample Size
We recommend a sample size of 150 eyes, distributed according to the ANSI Z80.10-2003 
standard.  However, we will consider an alternative sample size, if supported by a valid 
sample size estimate.   
5 See https://www.fda.gov/downloads/MedicalDevices/DeviceRegulationandGuidance/
GuidanceDocuments/ucm089593.pdf.
8 Contains Nonbinding Recommendations 
 
4.  Testing Protocol 
We recommend that your testing protocol follow Annex A.3 and Annex B, of ANSI 
Z80.10-2003 or equivalent method.  If you use a different protocol, we recommend you 
provide a complete description.  However, if you followed any portions of ANSI Z80.10-
2003, we recommend you indicate which ones.  
 
5.  Analysis of Results 
We recommend that you analyze your results as described below. 
 
a.  Scatter Plot of Measured IOP Values 
We recommend that you submit a scatter plot showing the IOP values measured by 
your tonometer on the y-axis versus the Goldmann type tonometer on the x-axis.  We 
also recommend that you submit a linear regression of the scatter plot data, showing 
the resulting line, its equation, and the correlation coefficient.  
 
b.  Bland-Altman type plot 
We recommend that you submit a Bland-Altman type plot showing the paired 
differences between the reference Goldmann-type tonometer and your tonometer 
readings (y-axis) versus the mean of the Goldmann-type tonometer and your 
tonometer readings (x-axis).   
 
We also recommend that you provide the mean and standard deviation of the paired 
differences, and show the mean and two standard deviations around it as horizontal 
lines on the plot.  If you make multiple measurements on the same eye with either the 
Goldmann-type or your tonometer, we recommend that you use the mean of the 
normal clinical outputs of the tonometer in your analysis. 
 
c.  Comparability to a Goldmann-type Tonometer 
We recommend that you tabulate the number and percent of paired differences, i.e., 
[reference tonometer measurement]  [your device measurement] that exceed the 
tolerance for each pressure range as described in ANSI Z80.10-2003 or equivalent 
method.   
 
To show comparability to the Goldmann-type tonometer, no more than 5% of the 
paired differences should exceed the tolerance for each pressure range.  If more than 
5% of paired differences in your study exceed the tolerance, we recommend that you 
explain these results and provide a scientifically sound rationale for the equivalence of 
your device. 
 
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FDA believes the devices addressed by this guidance document is a non-significant risk 
device, therefore the study is subject to the abbreviated requirements of 21 CFR 812.2(b).6  
In addition to the requirements of section 21 CFR 812.2(b), sponsors of such trials must 
comply with the regulations governing institutional review boards (21 CFR Part 56) and 
informed consent (21 CFR Part 50). 
 
9.  Validation of Cleaning and Sterilization Methods  
For single use devices that are provided sterile, the device should be sterile with a sterility 
assurance level (SAL) of 1 x 10-6 using a sterilization cycle validated in accordance with the 
Quality System Regulation (QSR) (21 CFR Part 820).  We also recommend you provide the 
sterilization information described in the guidance entitled, Updated 510(k) Sterility Review 
Guidance K90-1.7  
 
For tip covers, we recommend high-level disinfection or sterilization before use. 
 
If the device is reusable, we recommend that you identify the method that you used to validate the 
cleaning, disinfection, and sterilization of your device.  (See also Section 12.  Labeling.)   
 
10.  Biocompatibility 
We recommend that you evaluate the biocompatibility of the patient-contacting materials as 
described in the International Standard Organization (ISO) standard ISO-10993, "Biological 
Evaluation of Medical Devices Part 1: Evaluation and Testing,8 for limited contact with intact 
corneas.  If identical materials and identical material processing are used in a predicate device 
with the same type and duration of patient contact, you may identify the predicate device in lieu 
of performing biocompatibility testing.  We also recommend that you provide a list of the patient-
contacting materials in your device. 
 
11.  Electrical Safety and Electromagnetic Compatibility 
We recommend that you address the electrical safety and electromagnetic compatibility of your 
device by following both standards below or equivalent method.  
 
  International Electrotechnical Committee (IEC) standard IEC 60601-1,Medical Electrical 
 
Equipment Part 1: General Requirements for Safety 
 
  IEC 60601-1, Part 1-2: General Requirements for Safety - Collateral Standard: 
Electromagnetic Compatibility - Requirements and Tests 
 
                                                 
6 See http://www.fda.gov/oc/ohrt/irbs/devices.html#risk
7 http://www.fda.gov/cdrh/ode/guidance/361.html. 
8 http://www.fda.gov/cdrh/g951.html. 
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12.  Labeling  
The premarket notification should include labeling in sufficient detail to satisfy the requirements 
of 21 CFR 807.87(e).  The following suggestions are aimed at assisting you in preparing labeling 
that satisfies the requirements of 21 CFR Part 801.9
 
As a prescription device, under 21 CFR 801.109, the device is exempt from having adequate 
directions for lay use.  Nevertheless, we recommend providing clear and concise instructions that 
delineate the technological features of the specific device and how the device is to be used on 
patients.  Instructions should encourage local institutional training programs designed to 
familiarize users with the features of the device and how to use it in a safe and effective manner. 
 
Labeling should include the indications for use of your device, for example: 
 
A tonometer is indicated for measuring intraocular pressure to aid in the screening and 
diagnosis of glaucoma. 
 
Labeling should contain a summary of all performance testing of the device as outlined in 
Sections 7 and 8, including accuracy and repeatability statistics and, if applicable, comparability 
testing to a Goldmann-type reference tonometer.  Additionally, we recommend that you include in 
the labeling any relevant references that describe the scientific basis for any features that adjust 
measured IOP. 
 
Labeling should list separately single use, disposable, and reusable parts.   
 
If the end user is to sterilize any parts, we also recommend that your labeling include instructions 
for cleaning, disinfection, and sterilization based on the validation process described in your 
submission.  Sterilization instructions should be sufficient to achieve a sterility assurance level 
(SAL) of 1 x 10-6.   
 
                                                 
9 Although final labeling is not required for 510(k) clearance, final labeling must comply with the 
requirements of 21 CFR Part 801 before a medical device is introduced into interstate commerce.  
In addition, final labeling for prescription medical devices must comply with 21 CFR 801.109.  
Labeling recommendations in this guidance are consistent with the requirements of Part 801. 
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