Hhs publication fda 87‑4002 impact resistant lenses questions and answers project Officers

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HHS Publication FDA 87‑4002


Project Officers

Walter M. Snesko and John F. Stigi

Office of Training and Assistance

Revised September 1987


Public Health Service

Food and Drug Administration

Center for Devices and Radiological Health

Rockville, Maryland 20857

Snesko, W. M. and J. F. Stigi. Impact Resistant Lenses: Questions and Answers. HHS Publication (FDA) 87‑4002 (September 1987) (27 pp.)

Eyeglasses and sunglasses are medical devices. As such, they are subject to medical device regu­lations under the Food, Drug, and Cosmetic Act. To reduce the number of eye injuries, eyeglasses and sunglasses must be fitted with impact ­resistant lenses. Glass lenses, plastic lenses, or laminated glass lenses can be made impact resis­tant by any method. However, all lenses must be capable of withstanding the impact test described under 21 CFR Part 801.410(d)(2). This booklet answers questions on such topics as the lens testing apparatus, records maintenance, and exemptions to testing.


Abstract 2
Introduction 4
Testing Apparatus and Procedures 6
Who Must Test and When 8
Exemptions 9

Sampling Plans 10

Records 10

Dispensing Untested Lenses 11

Frames and Designs 11

Other Lens Types 12

Premarket Notification 13

Liability 13

References 14


A. FDA District Offices 15

B. Voluntary Standards 17

The Food and Drug Administration (FDA), the leading consumer protection agency in the United States, began to regulate eyeglasses in the early 1970's.
In 1984, 120 million persons in the U.S. wore eyeglasses and 19 million lenses were imported, constituting a $7.5 billion industry in the United States.
Eyeglasses and sunglasses are medical devices. As such, they are subject to medical device regulations under the Food, Drug, and Cosmetic Act. Other forms of eyewear such as safety glasses and sports glasses ‑‑ including swimmers' racing goggles, ski goggles, and racquetball glasses ‑‑ are not regulated as medical devices unless they have prescription lenses, and thus are not subject to the medical device regu­lations.
To reduce the number of eye injuries, eyeglasses and sunglasses must be fitted with impact‑resistant lenses. Consumers should understand that the regulation requires a minimum level of impact resistance but does not require that the lens act as an unbreakable shield. Glass lenses, plastic lenses, or laminated glass lenses can be made impact resistant by any method. However, all lenses must be capable of withstanding the impact test described under 21 CFR Part 801.410(d)(2) (see Appendix D for the complete ruling, hereafter referred to as "the regulation"). The number of lenses actually tested for impact resistance within each batch or lot varies depending on material and type of lens [21 CFR Part 801.410(c)(3)]: all glass lenses for pre­scription use must be tested, but statistical sampling is allowable for over‑the‑counter glass lenses, glass laminate and plastic lenses, and also for prescription glass laminate and plastic lenses. Certain lenses which are prescribed infrequently for specific, uncommon visual needs have physi­cal designs that render them unsuitable for impact testing. These lenses [see 21 CFR 801.410(e)(3) for specific types] must be rendered impact resistant but need not be tested. Statistically accurate samples of plastic lenses (prescription or over the counter (OTC)) and glass OTC lenses must be tested for impact resistance. Because not all lenses are tested, it is possible that some lenses are not impact resistant, although most will be.

Consumers, manufacturers, and sellers should remember that the strength of any lens is related to the condition of its surface. All lenses lose their impact strength in direct proportion to the breakdown of the polished surfaces. The greater the number and depth of any scratches, the weaker the lens becomes. For consumers, there is an inherent hazard in continuing to wear scratched lenses because their impact strength is reduced. Spectacle wearers also should be aware that streetwear or dress plastic lenses are not neces­sarily impact resistant simply because they are manufac­tured of a plastic material. Although plastic lenses must pass the impact test, they are not necessarily the same as "safety glasses" for industrial use.

Since the first edition of this booklet was published in June 1972, considerable changes have occurred in Federal regulation of impact‑resistant lenses. This third edition explains the changes and continues to answer questions that industry and consumers most frequently ask FDA about impact‑resistant lenses.
Factors having significant influence on current require­ments of the regulation are as follows:

  • the Medical Device Amendments of May 28, 1976, which established responsibility for enforcement and administration by the Center for Devices and Radiological Health (CDRH) within FDA.

  • experience by FDA in applying the regulation to eyeglass and sunglass lenses.

  • technological advancements in eyeglass lenses. changes in the marketplace for eyeglasses.

  • the amendment of April 6, 1979, (44 FR 20676) to the regulation, which (1) allowed lenses to be tested for impact resistance by any test equivalent or superior to the drop-ball (referee) test, and (2) described specific prescription lenses that must be impact resistant, but need not be tested for impact resistance.

For more information on this topic, contact your local FDA district office (see Appendix A) or CDRH at either of the following addresses:

Food and Drug Administration

Division of Compliance Operations

8757 Georgia Avenue

Silver Spring, MD 20910

Division of Small Manufacturers Assistance

5600 Fishers Lane (HFZ‑220)

Rockville, MD 20857

Phone (800) 638‑2041

1. Q. What is the "Referee" or "Drop Ball" test and how is it done?
A. The test used to determine impact resistance, and which is described in the regulation, is commonly called the "drop ball test." The term "referee test" refers to the use of this test in determining com­pliance with a regulation.
The exact procedure for the impact test is given in 29 CFR 801.410(d)(2) (see Appendix C). In brief, though, a 5/8‑inch steel ball weighing approximately 0.56 ounce is dropped from a height of 50 inches upon the horizontal upper surface of the lens. The ball must strike within a 5/8‑inch diameter circle located at the geometric center of the lens. The ball may be guided but not restricted in its fall by being dropped through a tube extending to within approxi­mately 4 inches of the lens. To pass the test, the lens must not fracture; for the purpose of this regu­lation, a lens will be considered to have fractured if it cracks through its entire thickness and across a complete diameter into two or more separate pieces, or if any lens material visible to the naked eye becomes detached from the ocular surface (i.e., the surface of the lens that is closest to the eye when the lens is in actual use).
2. Q. What criteria does FDA use to determine whether a fractured lens passes the test?
A. If the crack or fracture in any lens continues from the outside (objective) surface through to the ocular surface, the crack is considered to be through the lens's entire thickness and the lens has failed the test. However, if a laminated lens has a crack only through to the lamina, not disturbing the other side of the lens, then the crack is not considered to be through the thickness and the lens has passed the test.

A lens is not considered impact resistant if it cracks during the test and each piece is approximately 50 percent of the lens (i.e., across the diameter). However, if, for example, only 1/4 of the lens is separated from the remaining lens (not across the diameter), the lens may be considered impact resis­tant. Such determinations are subjective, and accep­tability of the lens may depend on whether the sample being tested has a high failure rate. For example, if the lot being tested was not well within Acceptable Quality Level (AQL) of 6.5, general in­spection level II in MIL STD 105D, and the decision to pass or fail the lot depended on this lens, the inspec­tor should be prudent and consider the lens unaccep­table. Likewise, a lens is not considered impact resistant if its ocular surface chips during the test. In use, this small segmented piece would represent a potential hazard to the eye.
3. Q. Must the apparatus used in the referee test have a tube to guide the steel ball as it falls toward the lens?
A. No. The regulation provides that a tube may be used, but is not necessary. If used, however, the tube must not interfere with the free fall of the ball.
4. Q. May a referee apparatus, which has a base and rigidly attached fixtures that weigh less than 27 pounds, be modified to meet the weight specifi­cation?
A. Yes. A heavier base plate may be used or a modifi­cation made, such as attaching the base plate to a workbench or table in such a way that the bench or table is considered to be an integral part of the support system or of the apparatus itself. FDA requires that the apparatus used to test the lenses have a solid support system. FDA will use test fixtures weighing more than 27 pounds.

5. Q. Does FDA require a neoprene gasket on testing apparatus requiring support tubes?
A. Yes.
6. Q. May the manufacturer secure the lens in the testing apparatus to prevent lens movement or repeated impact with the ball following the first impact with the ball?
A. The regulation contains no provisions for securing the lens. FDA does not intend to secure the lens during testing. Nevertheless, measures to protect the lens from damage during testing are permitted, as long as these measures do not interfere with the validity of the test results. (See Appendix C.)
7. Q. How may manufacturers test laminated lenses for impact resistance?
A. Laminated eyeglasses or sunglasses may be drop ball tested individually or on the same statistical basis as plastic lenses unless they are of a type, as specified under 21 CFR 801.410(c)(3), unsuitable for impact testing.
8. Q. Must manufacturers test plastic lenses in a variety of thicknesses?
A. Manufacturers must test plastic lenses on a batch ­sampling statistical basis. The regulation states that the lenses tested "shall be representative of the finished forms ... of minimal lens thickness ...." (see Appendix C). In practice, this means that manufac­turers who sell partially‑ground lens blanks to optical laboratories or other reprocessors must (1) tell these customers the degree of thickness at which the lenses were tested and (2) caution them to test each lens that is further processed to a thickness less than this minimal level.

9. Q. May the manufacturer use tests other than the referee test to demonstrate impact resistance?

A. An alternate method of testing the impact resistance of lenses may be used if the manufacturer' can prove that the alternate method is equal or superior to the referee test. The FDA need not preapprove any alternate testing method.

10. Q. If a lens breaks during an FDA test, is the manufacturer in violation of the regulation?

A. Not necessarily. Each situation will be reviewed and violations determined by the conditions surrounding the case and by the testing status of the lens (i.e., whether the lens was individually tested or was part of a batch sampled on a statistical basis).

11. Q. Who should perform the test for impact resistance?
A. The manufacturer, as defined in the answer to question 12, is responsible for performing the test for impact resistance.
12. Q. In terms of the regulation, who is the manufacturer?
A The manufacturer is the person who puts the lens in the form ready for its intended use or who alters the physical or chemical characteristics of the lens by such acts as grinding, heat treating, beveling, or cutting. For the purpose of this regulation the term "manufacturer" includes a company that imports eyeglasses for resale.
13. Q. At what stage of fabrication (manufacture) must impact‑resistant lenses be tested?

  1. The lenses must be tested when fabrication and treatment are complete and the lenses are ready for insertion into the eyeglass or the sunglass frames.

The exception is that plastic lenses may be tested in the "uncut‑finished" stage (i.e., when both surfaces are formed to prescription curvatures and thickness, but edges of the lenses are not yet cut to frame size and shape).

14. Q. Does the regulation apply to lenses manufactured abroad for import into this country?
A. Yes. The regulation applies to all lenses in interstate commerce, regardless of their origin.
15. Q. May an optical wholesaler or processing laboratory supply non‑impact‑resistant lenses to a retailer who, in turn, wants to render them impact resistant?

  1. Yes.

16. Q. What is the interpretation of "finished lens" and "finished' form," as used in the regulation? (See Appendix D.)

A. A "finished lens" is in "finished form" when all edging operations have been completed prior to the lens being mounted into a frame and delivered to the patient. At this point, a monolithic (nonlaminated) glass lens is ready to be treated for impact resis­tance and tested.
17. Q. If retailers put untested plano (noncorrective) lenses in frames such as those used with customized sunglasses, must they render the plano lenses impact resistant and test them?
A. Yes. However, mass‑produced plano lenses for use in sunglasses need only be tested on a statistically significant, batch‑sampling basis.
18. Q. May a glass lens, after it has been chemically or thermally treated for impact resistance, be processed further in any way?
A. Lenses that are treated for impact resistance by induced surface compression may be re‑edged or modified for power. However, the beneficial effects of surface compression may be substantially reduced. Such lenses must be retreated and tested before they are dispensed to the patient.
19. Q. Does FDA stipulate one method that must be used in rendering eyeglass lenses impact resistant?
A. No. Any proven method may be used, provided that the lenses pass the referee test or an equivalent test.

20. Q. What special prescription eyeglass lenses are exempt from the impact test?
A. As designated in the regulation, the following special lenses are exempt from statistical sampling and 100 percent impact testing: prism segment multifocals, slab‑off prisms, lenticular cataracts, iseikonics, depressed segment one‑piece multifocals, biocon­caves, myodiscs and minus lenticulars, and custom laminate and cemented assemblies. In addition, raised multifocal lenses need not be tested beyond initial design testing. All of these types of lenses are required to be made of impact‑resistant materials or to be treated for impact resistance.
21. Q. Are toy sunglasses subject to the provisions of the regulation?
A. Yes. Toy sunglasses are subject to the provisions of the Federal Food, Drug, and Cosmetic Act, and if intended for wear by children, they also are subject to the provisions of the Federal Hazardous Sub­stances Act, as amended by the Child Protection and Toy Safety Act of 1969.

22. Q. How does the regulation define the word "batch" as used in the phrase "statistically significant batch testing?"
A. The regulation allows each manufacturer to define what constitutes a batch for their operation, as long as a "batch" is a recognizable or identifiable entity, and appropriate records are maintained.
23. Q. Does FDA require manufacturers to use a specific sampling plan when performing "statistically signifi­cant" sampling of lenses?
A. FDA does not require the use of a specific sampling plan, however, the plan chosen must be statistically significant. FDA has accepted the use of MIL‑STD 105D, April 1963, "Sampling Procedures and Tables for Inspection by Attributes," Acceptable Quality Level of 6.5, General Inspection Level II. Another acceptable plan, used by many foreign manu­facturers, is the LTPD 15 percent sampling plan. The sample size is smaller than MIL‑STD 105D with a correspondingly smaller rejection number. Other sampling plans are acceptable if shown to be statistically significant.

24. Q. What are the recordkeeping requirements on partially finished lenses furnished by one manufacturer for completion by another?
A. Records must be kept to show how lenses were rendered impact‑resistant, when and how they were tested for impact resistance, and by whom in the processing chain these actions were accomplished.

25. Q. What records must retailers maintain?
A. If the retailer is also the manufacturer (see question 12), then the retailer is responsible for assuring the impact resistance of any lenses processed. The recordkeeping requirements of the manufacturer apply to the retailer in this case.
In addition, the regulation requires retailers of pre­scription lenses to keep for 3 years records of the names and addresses of persons buying impact­ resistant eyeglasses and sunglasses. The regulation does not require retailers to keep records of the names and addresses of people buying nonprescrip­tion glasses and sunglasses.
26. Q. Does the regulation call for coding of invoices, shipping documents, and containers pertaining to sale and distribution of impact‑resistant lenses?

  1. No.

27. Q. Under what circumstances may retailers dispense lenses that are not impact‑resistant?
A. Lenses that are not impact resistant may be dispensed when a physician or optometrist deter­mines that impact‑resistant lenses will not fulfill the visual requirements of a particular patient. The physician or optometrist directs this in writing and gives written notification to the patient.
28. Q. Can a retailer supply a non‑impact‑resistant lens if a patient requests it or if the patient/customer agrees to assume all responsibility?

  1. No. Non‑impact‑resistant lenses may be provided only when the physician or optometrist determines that impact‑resistant lenses will not fulfill the visual requirements of the patient. (See question 27.) In such cases the physician or optometrist must give give notice in writing to the patient, explaining that the patient is receiving a lens that is not impact resistant.

29. Q. May a physician or optometrist prescribe non­impact‑resistant lenses for a patient for purely cos­metic reasons?

A. No. If medical problems are related to cosmetic considerations, however, the physician or optometrist may invoke special exemption provisions of the regulation based on professional judgment. For example, if the patient's prescription cannot be filled by impact‑resistant lenses because the physician or optometrist knows from previous experience that the weight of the heavy lenses may cause headaches, undue pressure on the bridge of the nose or ears, pressure sores, etc., the physician or optometrist may find that the visual requirements of the patient cannot be met by use of impact‑resistant lenses.
30. Q. Under rare circumstances ‑ such as an emergency in which a surgeon's eyeglasses break just before a scheduled surgery, and the broken lenses must be replaced immediately ‑ may a retailer provide non­impact‑resistant lenses?

  1. If all else fails, and the situation is indeed critical, the surgeon may be provided with non‑impact ­resistant lenses on a temporary basis only and with the knowledge and consent of all involved.

31. Q. Does FDA restrict the properties or design of impact‑resistant lenses?
A. The regulation requires only that lenses be made impact resistant and be impact tested. No other FDA regulations are currently in effect concerning other properties or design of impact‑resistant lenses.

32. Q. Must rimless eyewear pass the referee test?
A. Yes. Rimless eyewear must conform to the regu­lation and pass the referee test or its equivalent.
33. Q. Does FDA regulate spectacle frames?
A. Yes. Spectacle frames are regulated as medical devices. Spectacle frames are proposed for classi­fication under 886.5270 as Class II medical devices.

34. Q. Are safety lenses the same as impact‑resistant lenses?
A. No. Safety lenses ordinarily are used in the indus­trial setting and are highly impact resistant, whereas impact‑resistant lenses are used in street wear or dress wear eyeglasses.
35. Q. Does the regulation apply to industrial safety lenses?
A. It is not necessary to apply the FDA impact require­ment to industrial safety lenses, because these lenses are required by industrial standards to withstand impact stress nearly three times greater than the degree of impact resistance required by FDA. Industrial lenses are regulated by the Occupational Safety and Health Administration of the Department of Labor.
36. Q. Are impact‑resistant lenses shatterproof or non­breakable?
A. Neither. They are impact resistant, in that they are capable of passing the referee test (drop ball test) as described in the regulation. However, impact‑resis­tant lenses may break or shatter under certain condi­tions. Impact‑resistant lenses should not be worn in areas or situations requiring industrial safety lenses.

37. Q. Are the various forms of goggles or face masks, such as used in skiing, swimming, snorkeling, etc., subject to the provisions of this regulation?
A. No. The regulation applies only to eyeglasses and sunglasses; that is, to those products that are considered medical devices for street wear or dress use.
38. Q. Must demonstration lenses that are used in eye­glasses and sunglasses for display purposes be impact resistant?
A. Demonstration lenses are not required to be impact resistant. However, precautions must be taken to assure that these display units are not ultimately sold to the consumer. Manufacturers of eyeglass or sunglass frames with demonstration lenses can use any of various options to ensure that these units are not used by the public. These options are listed below.
1. At least one lens in each pair of eyeglasses should have the word "demonstration" etched in its lower quadrant. The letters should be large enough to be easily seen with normal vision.
2. A visible line may be drawn through the center of the lens.
3. A notch can be removed from the lower quadrant of at least one lens in each pair of eyeglasses.
4. A hole can be drilled in each lens in the wearer's line of sight.

39. Q. Because spectacle frames and nonprescription sun­glasses are common products, must manufacturers submit a premarket notification 510(k), like other medical device manufacturers?

A. Yes, however spectacle frames and sunglass manu­facturers should not make complex premarket notifi­cation 510(k) submissions. When submitting the premarket notification 510(k), specifically address the following areas:
For spectacle frames, discuss the material used in its manufacture. If it is plastic, has it been tested for flammability? What are its dermatological charac­teristics? How does the strength and resilience of the proposed material compare to that commonly used?
For sunglasses, discuss whether the product consists of absorbing, reflective, tinted, polarizing, or photo­sensitized lenses. If claims are made for reduction of UV transmission, how was the percentage of re­duction determined? Especially for a new material, how does it respond to drop ball testing?

40. Q. What is the personal liability, with regard to injury claims, of a physician, optometrist, optical retailer, or optical wholesaler under the regulation?
A. Personal liability should be discussed with an attorney or with professional guilds or associations and their counsels.

1. American National Standards Institute. "Practice for Occupational and Educational Eye and Face Protection." ANSI Z87.1, New York (1979).
2. American National Standards Institute. "Recom­mendations for Prescription Ophthalmic Lenses." ANSI Z80.1, New York (1979).
3. American National Standards Institute. "Sunglasses and Fashion Eyewear." ANSI Z80.3, New York (1986).
4. American National Standards Institute. "Dress Frames." ANSI Z80.5, New York (1986).

  1. U.S. Department of Defense. "Sampling Procedures and Tables for Inspection by Attributes." MIL‑STD‑105D. Washington, D.C. (1975).

6. Department of Health, Education, and Welfare. Question and Answer Pamphlet #1 on Impact‑Resistant Lenses. HEW Publication (FDA) 72‑4002 (1972).

American national standards can be obtained from the American National Standards Institute, 1430 Broadway, New York, NY 10018.
Military standards can be obtained from the U.S. Naval Publications and Forms Center; 5801 Tabor Avenue, Philadelphia, PA, 19120.

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The American National Standards Institute (ANSI) standard 280.1, "Recommendations for Prescription Oph­thalmic Lenses," permits the use of a plastic film on top of the lens during the impact test, as follows:
"To avoid surface damage from the impact of the ball, the lens may be inserted in a polyethylene bag or covered with a polyethylene sheet before testing. The thickness of polyethylene covering the lens shall not exceed 0.076 mm (0.003 in.), and shall conform to the requirements for polyethylene sheeting, Type II, given in ANSI Speci­fication for Polyethylene Film and Sheeting, ANSI/ASTM D2103, 1971, or the latest revision thereof. The pro­tective sheet shall be in contact with the lens surface in the test area before the ball is dropped."
FDA agrees to accept this practice when a method of 100 percent testing of finished lenses is used, although FDA realizes that the impact energy of the falling ball, as transmitted to the lens, may be reduced by more than 10 percent. FDA still affirms, however, that in any case of dispute, the referee test as described in 21 CFR 801.410 will prevail. Also, for any new developments in the materials of lenses, the referee test shall be used in verifying conformance of the new material to these specifications.
Restriction: When the impact resistance of the lenses is verified by a statistical sampling plan, FDA insists that the referee test, or its equivalent or superior, be used without the plastic film.

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