Endotoxin Testing 
Recommendations for Single-Use 
Intraocular Ophthalmic Devices 
Guidance for Industry and Food 
and Drug Administration Staff   
Document issued on August 17, 2015.  
 
The draft of this document was issued on April 17, 2014. 
For questions regarding this document, contact the Division of Ophthalmic and Ear, Nose, and 
Throat Devices (DOED) at 301-796-5620. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Devices and Radiological Health 
Office of Device Evaluation 
Division of Ophthalmic and Ear, Nose, and Throat Devices 
Intraocular and Corneal Implants Branch 
Contact Lens and Retinal Devices Branch 
  Diagnostic and Surgical Devices Branch  Contains Nonbinding Recommendations 
Preface 
Public Comment  
You may submit electronic comments and suggestions at any time for Agency consideration to 
http://www.regulations.gov. Submit written comments to the Division of Dockets Management, 
Food and Drug Administration, 5630 Fishers Lane, Room 1061, (HFA-305), Rockville, MD 
20852. Identify all comments with the docket number FDA-2014-D-0332. 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. You may also send an e-mail request to CDRH-
Guidance@fda.hhs.gov to receive an electronic copy of the guidance. Please use the document 
number 1836 to identify the guidance you are requesting. 
  2  Contains Nonbinding Recommendations 
Endotoxin Testing Recommendations for 
 
Single-Use Intraocular Ophthalmic Devices
 
 
Guidance for Industry and  
Food and Drug Administration Staff 
This guidance represents the current thinking of the Food and Drug Administration (FDA or 
Agency) current thinking on this topic.  It does not establish any rights for any person and is 
not binding on FDA or the public.  You can use an alternative approach if it satisfies the 
requirements of the applicable statutes and regulations.  To discuss an alternative approach, 
contact the FDA staff responsible for this guidance as listed on the title page.  
 
I.  Introduction  
This guidance document was developed to notify manufacturers of the recommended endotoxin 
limit for the release of intraocular devices and single-use intraocular ophthalmic surgical 
instruments/accessories in an effort to mitigate future Toxic Anterior Segment Syndrome 
(TASS) outbreaks. TASS is a sterile inflammatory condition localized to the anterior segment of 
the eye following intraocular surgery. It has been associated with significant decreases in vision 
and may require additional surgical procedures, including corneal transplants and glaucoma 
surgery, to resolve some of its sequelae.   
 
National outbreaks of TASS have been associated with endotoxin. Devices used inside the eye, 
including intraocular devices and single-use intraocular ophthalmic surgical 
instruments/accessories, can potentially be contaminated with endotoxin as part of the 
manufacturing, sterilization, or packaging processes. This guidance document provides 
recommendations for endotoxin limits as well as endotoxin testing to manufacturers and other 
entities involved in submitting premarket applications (PMAs) or premarket notification 
submissions [510(k)s] for different categories of intraocular devices to aid in the prevention of 
future outbreaks of TASS.   
FDAs guidance documents, including this guidance, do not establish legally enforceable 
responsibilities. Instead, guidances describe the Agencys 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. 
  3  Contains Nonbinding Recommendations 
II.  Definitions 
A.  Intraocular Fluids: A nongaseous fluid intended to be introduced into the eye to aid 
performance of surgery such as to maintain anterior chamber depth, preserve tissue 
integrity, protect tissue from surgical trauma or function as a tamponade during retinal 
reattachment. 21 CFR 886.4275. 
1.  Ophthalmic Viscosurgical Device (OVD):  Both viscous and viscoelastic 
intraocular fluids intended for use during surgery in the anterior chamber as a 
surgical aid to maintain space in the eye and protect ocular tissue from surgical 
trauma. They are usually intended for use in cataract surgery, corneal transplant 
surgery, and glaucoma filtration surgery. These devices are typically pre-
packaged in a syringe and require PMA approval prior to being marketed. This 
term includes viscoelastic surgical aids. 
B.  Intraocular Lenses (IOLs):  An artificial lens intended to be implanted to replace the 
natural lens of an eye. 21 CFR 886.3600. IOLs can be used to restore vision and replace 
the natural lens of the eye after it is removed during cataract surgery. IOLs can also be 
used in eyes where the natural lens is not removed but that require correction of refractive 
error. Examples of types of IOLs include monofocal, toric, multifocal, accommodative, 
iris reconstruction and phakic. Iris reconstruction lenses are used to cosmetically correct 
defects in the appearance of the eye, usually caused by the absence of an iris. 
C.  Capsular Tension Rings:  A prosthetic device designed to stabilize the crystalline lens 
capsule in the presence of weak or partially absent zonules in patients undergoing 
cataract extraction with an intraocular lens. 
D.  Glaucoma Devices:  A device used to treat glaucoma, a condition in which the pressure 
within the eye (i.e., intraocular pressure) is abnormally high, resulting in damage to the 
optic nerve. These devices are often partially implanted in the anterior segment of the eye 
with the other portion of the device residing on the eye. These devices include aqueous 
shunts (21 CFR 886.3920). 
E.  Phacofragmentation System:  A phacofragmentation system is an AC-powered device 
with a fragmenting needle intended for use in cataract surgery to disrupt a cataract with 
ultrasound and extract the cataract. 21 CFR 886.4670. The hand piece is composed of a 
tip that delivers ultrasound energy which emulsifies the lens and aspirates lens material 
from its open end.  
1.  Sleeves: Surrounding the tip of the phacofragmentation handpiece is the sleeve, 
which is often of rubbery consistency and allows for irrigation around the tip as 
well as a barrier to tip penetration into lens material.   
2.  Tubing:  Any lumened device that transmits fluid into or out of the eye.   
F.  Endotoxin:  High molecular weight complex associated with the cell wall of Gram-
negative bacteria that is pyrogenic in humans and specifically interacts with Limulus 
amebocyte lysate (LAL).1 
G. Endotoxin unit (EU):  Standard unit of measure for endotoxin activity initially 
established relative to the activity contained in 0.2 ng of the U.S. Reference Standard 
Endotoxin Lot EC-2 (USP standard reference material). Endotoxin is expressed in 
International Units (IU) and one EU is equal to one IU.1 
H. Anterior segment:  The front third of the eye including all structures located between the 
front surface of the cornea and vitreous. 
  4  Contains Nonbinding Recommendations 
I.  Anterior chamber:  The space in the eye that is behind the cornea and in front of the 
iris.  It contains aqueous humor.  
J.  Aqueous humor:  A transparent, watery fluid circulating in the anterior and posterior 
chamber of the eye. It maintains the intraocular pressure of the eye, provides amino acids 
and glucose to the avascular ocular tissues and plays a role in the immune response of the 
eye.    
K. Bacterial endotoxin test (BET):  Assay for measuring active endotoxin by combining a 
liquid test sample with Limulus amebocyte lysate (LAL) reagent and measuring the 
resulting proportional reaction by gel-clot, turbidimetric, chromogenic, or other validated 
means of detection.1 
III.  Background 
TASS has been increasing in frequency over the past decade from approximately 1 in 1,000 to 
about 2 in 100. 2-4  Some cases of TASS are severe enough to require secondary surgical 
interventions including glaucoma surgery and corneal transplantation.5 The use of inadequately 
or improperly processed ophthalmic surgical instruments is one of many factors suggested as a 
potential cause of TASS.6-9 In many TASS cases, bacterial endotoxin from medical devices is 
believed to cause the inflammation.10,11 Endotoxin was found to be an intrinsic contaminant of a 
balanced salt solution used in cataract surgery that resulted in a TASS outbreak in 2005 
involving 112 patients.12 
 
Because bacteria thrive in media containing water, medical devices that are aqueous in nature, 
contain an aqueous component, or are otherwise exposed to water during the manufacturing 
process are vulnerable to bacterial proliferation and subsequent endotoxin contamination. Thus, 
ophthalmic viscosurgical devices (OVDs) that are commonly used in ophthalmic surgery are 
prone to endotoxin contamination. Further, the raw materials used in fabricating sodium 
hyaluronate (HA)-based OVDs, which are of biological origin, can also be a source of 
endotoxins. It has been shown that endotoxin in viscous materials such as OVDs incite more 
inflammation intraocularly than endotoxin in aqueous solution due to the prolonged contact with 
sensitive ocular tissue.13   
 
The general principles of endotoxin testing, as described in the most recent FDA-recognized 
versions* of United States Pharmacopeia (USP) <85> Bacterial Endotoxin Test,14 and the 
American National Standards Institute (ANSI)/Association for the Advancement of Medical 
Instrumentation (AAMI) ST72 Bacterial Endotoxins-Test Methodologies, Routine Monitoring 
and Alternatives to Batch Testing,1 can be followed to test the endotoxin levels of these single-
use intraocular ophthalmic devices. 
The endotoxin limit for OVDs specified in International Organization for Standardization (ISO) 
15798 (Ophthalmic implants-Ophthalmic viscosurgical devices) is 0.5 endotoxin units (EU) per 
milliliter (mL). During cataract surgery, the anterior segment of the eye can accommodate more 
than 0.3 ml of OVD after lens extraction and as much as 0.1 mL OVD may remain in the eye at 
                                                           
*A searchable database of FDA-recognized consensus standards is available at: 
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfStandards/search.cfm. 
  5  Contains Nonbinding Recommendations 
the end of the procedure. Hence, it is possible for 0.05 EU endotoxin to be left in the eye at the 
conclusion of the surgery, and this amount has been shown to cause inflammation.13 This same 
study showed that inflammation can be elicited by as little as 0.02 EU endotoxin in an OVD. 
Therefore, FDA does not recognize the endotoxin levels in the ISO 15798 (Ophthalmic implants-
Ophthalmic viscosurgical devices) standard.  
In ISO 11979-8 (Ophthalmic implants-Intraocular lenses-part 8: Fundamental requirements 
Amendment 1), the endotoxin limit for IOLs is 0.5 EU per device or less. Any endotoxin present 
on an IOL or other solid ophthalmic devices goes into solution when placed in an aqueous 
medium such as the aqueous humor. Studies have shown that 0.08 EU endotoxin in a balanced 
salt solution can elicit inflammation in the eye.13 Therefore, FDA does not recognize the 
endotoxin limit in ISO 11979-8 (Ophthalmic implants-Intraocular lenses-part 8: Fundamental 
requirements Amendment 1) or the limit in the ANSI series of standards for intraocular lenses.   
IV.  Scope 
The recommendations made in this guidance are applicable to devices used within the eye, either 
as permanent implants or as single-use devices used in intraocular surgery. These include:  
A.  Intraocular Fluids (21 CFR 886.4275, Class III), specifically viscoelastic surgical aid 
(LZP)  
B.  Anterior Segment Solid Devices 
1.  Intraocular lenses (21 CFR 886.3600, Class III), including 
a.  Intraocular lenses (HQL) 
b.  Multifocal intraocular lenses (MFK) 
c.  Phakic intraocular lenses (MTA) 
d.  Toric intraocular lenses (MJP) 
e.  Accommodative intraocular lenses (NAA) 
f.  Implantable miniature telescope (NCJ) 
g.  Iris reconstruction lenses (NIZ)  
2.  Capsular tension ring devices (Class III), including 
a.  Endocapsular rings (MRJ) 
3.  Glaucoma devices 
a.  Aqueous shunts (21 CFR 886.3920, Class II), including 
i.  Eye valve implant (KYF) 
b.  Other glaucoma devices (Class III) 
i.  Intraocular pressure lowering implants (OGO) 
4.  Phacofragmentation systems (21 CFR 886.4670, Class II), specifically the accessories 
of irrigation/aspiration sleeves and tubing (HQC) 
Endotoxin contamination of reusable manual ophthalmic surgical instruments is outside the 
scope of this guidance.  
  6  Contains Nonbinding Recommendations 
V.  Recommendations 
A.  Intraocular Fluids 
1.  OVDs 
a.  The recommended endotoxin limit for release testing is 0.2 EU/mL regardless of 
whether the intended site of use is the anterior or posterior segment. 
 
b.  Endotoxin test method validation: 
The viscosity of OVDs can interfere with the BET. In addition to the general 
validation principles described in USP <85> and ANSI/AAMI ST72, the 
validation of the BET should include recovery of known amounts of endotoxin 
added/spiked to the OVD. For each OVD that is to be marketed, random samples 
from 3 lots of the OVD should each be spiked with endotoxin to final 
concentrations of 0.1, 0.2 and 0.5 EU/mL.  Each test should be conducted in 
triplicate (i.e., each lot should be spiked and sampled three times for testing). The 
OVD should then be tested for endotoxin using the BET and the percentage 
endotoxin recovery should be calculated from the average of the values obtained 
from the three test samples from each lot. The detection limit may vary with the 
method used for testing (e.g., gel clot, turbidimetric and chromogenic) and, as 
such, it may be appropriate to experiment with different methods to ensure 
maximal recovery of endotoxin. For OVDs fabricated from HA of a high 
molecular weight, it may be appropriate to use an enzyme containing non-
detectable levels of endotoxin to break down large molecules and make endotoxin 
more accessible for testing. The use of enzyme digestion will avoid the use of a 
high dilution factor to overcome interference, which may be appropriate for the 
OVD to meet the endotoxin limit.13 
 
c.  If performed, animal testing for quality control and acceptance criteria with 
associated labeling claim: 
The phrase non-inflammatory in the labeling of an OVD should not be used 
since the OVD could elicit some inflammation but it may not be clinically 
significant. OVDs may be labeled as having low inflammatory potential if 
animal testing or another validated method for detecting inflammation is 
performed as a product release test. 
Although endotoxin in an OVD can be detected and quantified using a BET, the 
amount detected is only an approximation of the actual value due to the inherent 
limitations of the test. Furthermore, the amount of endotoxin detected can be 
affected by the unique properties of the individual OVD (e.g., the molecular 
weight), which could alter how the OVD binds to the ocular tissue and 
consequently the efficiency of enzyme digestion. Thus, the recommended method 
to assure that an OVD has low inflammatory potential is to test the product in the 
anterior segment of the eye with subsequent assessment of inflammation.  
Testing of an OVD in an animal model should be performed by injecting the 
OVD intracamerally.15 The eyes should then be monitored for clinical signs of 
  7  Contains Nonbinding Recommendations 
inflammation using a slit lamp for at least three days (i.e., 72 hours).  The test 
method should be validated by quantifying the inflammation elicited by injecting 
spiked OVD which results in intraocular doses of 0.01, 0.02 and 0.05 EU/eye, at a 
minimum.  
We recommend that sponsors who intend to perform this testing submit a Pre-
Submission to obtain feedback and recommendations from the Division of 
Ophthalmic and Ear, Nose, and Throat Devices on the animal testing validation, 
acceptance criteria for release testing, and any other methods of detecting 
inflammation. For more information on Pre-Submissions, please see Requests 
for Feedback on Medical Device Submissions: The Pre-Submission Program and 
Meetings with Food and Drug Administration Staff 
(http://www.fda.gov/downloads/MedicalDevices/DeviceRegulationandGuidance/
GuidanceDocuments/UCM311176.pdf).  
  
B.  Anterior Segment Solid Devices 
1.  The recommended endotoxin limit for all anterior segment solid intraocular 
devices is 0.2 EU/device. This limit applies to implants that are placed entirely 
in the anterior segment such as IOLs, iris reconstruction lenses, and capsular 
tension rings. For glaucoma devices, this limit applies to the segment of the 
device placed in the anterior chamber and the segment(s) contacting the aqueous 
humor even though the main portion of the device may reside outside the eye. For 
single-use cannulated or lumened devices (e.g., irrigation/aspiration sleeves and 
tubing), this limit applies to the fluid path and the portion of the device with 
aqueous humor contact. 
2.  Test sample preparation: 
The standard 40 mL/device extraction ratio can be adjusted to accommodate the 
small size of solid intraocular devices in accordance with the recommendation in 
the FDA Guidance for Industry Pyrogen and Endotoxin Testing: Questions and 
Answers 
(http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Guidanc
es/ucm314718.htm). The volume of the extraction solution chosen should also 
take into consideration the endotoxin limit for the device and the sensitivity of the 
LAL lysate used in the testing. ANSI/AAMI ST72 specifies the minimum 
extraction time as 15 minutes at 37-40C or one hour at controlled room 
temperature (typically 18-25C), or other demonstrated equivalent conditions.1 
Because of the extreme sensitivity of the eye to endotoxin, the FDA recommends 
that the extraction be performed at 37-40C with agitation for a minimum of 60 
minutes to maximize the extraction efficiency. For cannulated or lumened 
devices, sample preparation should consist of filling the fluid pathway with the 
extracting medium that has been pre-warmed to 37 1C and then held at 37 
1C for at least 60 minutes.   
  8  Contains Nonbinding Recommendations 
VI.  References
 
 
1.  American National Standards Institute, Instrumentation Association for the Advancement 
of Medical Instrumentation. Bacterial endotoxins-Test methodologies, routine 
monitoring, and alternatives to batch testing. ST72: 2011. 
2.  Ronge LJ. Toxic Anterior Segment Syndrome:  Why sterile isn't clean enough. EyeNet. 
San Francisco: American Academy of Ophthalmology; 2002. 
3.  Bodnar Z, Clouser S, Mamalis N. Toxic anterior segment syndrome: Update on the most 
common causes. J Cataract Refract Surg. Nov 2012;38(11):1902-1910. 
4.  Sengupta S, Chang DF, Gandhi R, Kenia H, Venkatesh R. Incidence and long-term 
outcomes of toxic anterior segment syndrome at Aravind Eye Hospital. J Cataract 
Refract Surg. Sep 2011;37(9):1673-1678. 
5.  Mamalis N, Edelhauser HF, Dawson DG, Chew J, LeBoyer RM, Werner L. Toxic 
anterior segment syndrome. J Cataract Refract Surg. Feb 2006;32(2):324-333. 
6.  Cutler CM, Brubaker J, Clouser S, Danford C, Edelhauser HE, Mamalis N. Toxic 
anterior segment syndrome:  common causes. J Cataract Refract Surg. 2010;36(7):1073-
1080. 
7.  Mamalis N. Toxic anterior segment syndrome. J Cataract Refract Surg. Feb 
2006;32(2):181-182. 
8.  Holland SP, Morck DW, Lee TL. Update on toxic anterior segment syndrome. Current 
Opinion in Ophthalmology. Feb 2007;18(1):4-8. 
9.  Maier P, Birnbaum F, Bohringer D, Reinhard T. Toxic anterior segment syndrome 
following penetrating keratoplasty. Arch Ophthalmol. Dec 2008;126(12):1677-1681. 
10.  Kreisler KR, Martin SS, Young CW, Anderson CW, Mamalis N. Postoperative 
inflammation following cataract extraction caused by bacterial contamination of the 
cleaning bath detergent. J Cataract Refract Surg. Jan 1992;18(1):106-110. 
11.  Richburg FA, Reidy JJ, Apple DJ, Olson RJ. Sterile hypopyon secondary to ultrasonic 
cleaning solution. J Cataract Refract Surg. May 1986;12(3):248-251. 
12.  Kutty PK, Forster TS, Wood-Koob C, et al. Multistate outbreak of toxic anterior segment 
syndrome, 2005. J Cataract Refract Surg. Apr 2008;34(4):585-590. 
13.  Buchen SY, Calogero D, Hilmantel G, Eydelman MB. Rabbit ocular reactivity to 
bacterial endotoxin contained in aqueous solution and ophthalmic viscosurgical devices. 
Ophthalmology. 2012;119(7):e4-e10. 
14.  The United States Pharmacopeial Convention. USP <85> Bacterial Endotoxin Test. 
15.  Buchen SY, Calogero D, Hilmantel G, Eydelman MB. Detecting endotoxin 
contamination of ophthalmic viscosurgical devices: intracameral versus intravitreal 
assays in rabbits. Ophthalmology. Jul 2012;119(7):e11-18. 
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