BOSTON XO® (hexafocon A) Contact Lenses are indicated for daily wear for the correction of refractive ametropia (myopia, hyperopia, astigmatism and presbyopia) in aphakic persons with non-diseased eyes. Also, the lenses may be prescribed in otherwise non-diseased eyes that require a rigid contact lens for the management of irregular corneal conditions such as keratoconus, pellucid marginal degeneration, or following penetrating keratoplasty or refractive (e.g. LASIK surgery). Furthermore, eyes suffering from certain ocular surface disorders may benefit from the physical protection, aqueous hydrated environment and the saline bath provided by scleral lens designs. Boston XO Scleral Lens designs for daily wear are indicated for therapeutic use for the management of irregular and distorted corneal surfaces where the subject: 1. cannot be adequately corrected with spectacle lenses 2. requires a rigid gas permeable contact lens surface to improve vision 3. is unable to wear a corneal rigid gas permeable lens due to corneal distortion or surface irregularities Common causes of corneal distortion include but are not limited to corneal infections as a result of scar formation secondary to refractive surgery (e.g. LASIK or radial keratotomy) or corneal transplantation. Causes may also include corneal degeneration (e.g. keratoglobus, pellucid marginal degeneration, Salzmann's nodular degeneration) and corneal dystrophy (e.g., lattice dystrophy, granular corneal dystrophy, Reis-Bucklers dystrophy, Cogan's dystrophy). The Boston XO Scleral Lens designs for daily wear are also indicated for therapeutic use in eyes with ocular surface disease (e.g. ocular Graft-versus-Host disease, Sjögren's syndrome, dry eye syndrome and Filamentary Keratitis), limbal stem cell deficiency (e.g. Stevens-Johnson syndrome, chemical radiation and thermal burns), disorders of the skin (e.g. atopy, ectodermal dysplasia), neurotrophic keratitis (e.g. Herpes zoster, Familial Dysautonomia), and corneal exposure (e.g. anatomic, paralytic) that might benefit from the presence of an expanded tear reservoir and protection against an adverse environment. When prescribed for therapeutic use for a distorted cornea or ocular surface disease, the Boston Scleral Lenses may concurrently provide correction of refractive error. The lenses may be disinfected using a chemical disinfection (not heat) system only.

BOSTON XO2® (hexafocon B) Contact Lenses are indicated for daily wear for the correction of refractive ametropia (myopia, hyperopia, astigmatism and presbyopia) in aphakic persons with non-diseased eyes. Also, the lenses may be prescribed in otherwise non-diseased eyes that require a rigid contact lens for the management of irregular corneal conditions such as keratoconus, pellucid marginal degeneration, or following penetrating keratoplasty or refractive (e.g. LASIK surgery). BOSTON XO2 Contact Lenses are also indicated for daily wear in an orthokeratology fitting program for the temporary reduction of myopia of up to 5.00 diopters in non-diseased eyes. Note: To maintain the orthokeratology effect of myopia reduction, lens wear must be continued on a prescribed wearing schedule. Furthermore, eyes suffering from certain ocular surface disorders may benefit from the physical protection, aqueous hydrated environment and the saline bath provided by scleral lens designs. Boston XO2 Scleral Contact Lens designs for daily wear are indicated for therapeutic use for the management of irregular and distorted corneal surfaces where the subject: 1. cannot be adequately corrected with spectacle lenses 2. requires a rigid gas permeable contact lens surface to improve vision 3. is unable to wear a corneal rigid gas permeable lens due to corneal distortion or surface irregularities Common causes of corneal distortion include but are not limited to corneal infections, trauma, tractions as a result of scar formation secondary to refractive surgery (e.g. LASIK or radial keratotomy) or corneal transplantation. Causes may also include corneal degeneration (e.g. keratoglobus, pellucid marginal degeneration, Salzmann's nodular degeneration) and corneal dystrophy (e.g., lattice dystrophy, granular corneal dystrophy, Reis-Bucklers dystrophy, Cogan's dystrophy). The Boston XO2 Scleral Lens designs for daily wear are also indicated for therapeutic use in eyes with ocular surface disease (e.g. ocular Graft-versus-Host disease, Sjögren's syndrome and Filamentary Keratitis), limbal stem cell deficiency (e.g. Stevens-Johnson syndrome, chemical radiation and thermal burns), disorders of the skin (e.g. atopy, ectodermal dysplasia), neurotrophic keratitis (e.g. Herpes zoster, Familial Dysautonomia), and corneal exposure (e.g. anatomic, paralytic) that might benefit from the presence of an expanded tear reservoir and protection against an adverse environment. When prescribed for therapeutic use for a distorted cornea or ocular surface disease, the Boston Scleral Lenses may concurrently provide correction of refractive error. The lenses may be disinfected using a chemical disinfection (not heat) system only.

Device Description

The Boston XO and Boston XO2 Rigid Gas Permeable (RGP) Contact Lenses are fluoro silicone acrylate copolymer rigid gas permeable contact lenses available in a variety of tints and may contain an ultraviolet light absorber. The hemispherical shells are available in several lens designs including spherical, aspherical, toric, scleral and irregular cornea designs.

AI/ML Overview

The provided document is a 510(k) summary for the BOSTON XO®/XO2® Rigid Gas Permeable Contact Lenses. It outlines the indications for use and compares the device to predicate devices to demonstrate substantial equivalence, rather than detailing a study proving the device meets specific acceptance criteria with explicit performance metrics.

Therefore, many of the requested details about acceptance criteria, study design, sample sizes, ground truth establishment, and expert involvement are not present in this type of regulatory document.

However, based on the information provided, here's what can be extracted:

Acceptance Criteria and Device Performance

The document does not explicitly state numerical acceptance criteria for performance or a study proving those criteria are met. Instead, it relies on demonstrating substantial equivalence to already approved predicate devices. The "performance" in this context refers to the physical and chemical properties of the lens materials.

The table below summarizes the physical comparison of the subject device (Boston XO & XO2 Scleral Lens) to predicate devices (BostonSight PD Prosthetic Device and Boston Scleral Lens). The acceptance criteria implicitly are that these properties are comparable to legally marketed predicate devices, and that the expanded indications for use for scleral lenses do not introduce new questions of safety or effectiveness.

Feature	Boston XO (hexafocon A) - Reported Performance	Boston XO2 (hexafocon B) - Reported Performance	Predicate Device (oprifocon A) - BostonSight PD Prosthetic Device	Predicate Device (oprifocon A) - Boston Scleral Lens
Refractive Index	1.415	1.424	1.423	1.423
Specific Gravity	1.27	1.19	1.24	1.24
Wetting Angle	49°	38°	56°	56°
Hardness	81	78	81	81
Modulus	1500 Mpa	1160 Mpa	1300 Mpa	1300 Mpa
Visible Light Transmittance	> 92%	> 95%	> 95%	> 95%
Water Content	<1%	<1%	<1%	<1%
Oxygen Permeability (Dk)	100	141	85	85

Study Information (as inferable from the document):

Sample sizes used for the test set and the data provenance:
- Test set sample size: Not applicable/Not provided. The submission states, "No performance data is required" as "There are no changes to the Boston XO (hexafocon A) and Boston XO2 (hexafocon B) Rigid Gas Permeable contact lens material or lens designs as part of this application. These materials have been previously cleared for scleral lens designs. This application is for labeling revisions."
- Data provenance: Not applicable, as detailed performance data from a new study is not provided. The comparison is based on existing, previously cleared material properties and indications of predicate devices.
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- Not applicable. No new clinical study requiring ground truth establishment by experts is described. The comparison is against established properties and indications of previously approved devices.
Adjudication method for the test set:
- Not applicable. No new clinical study requiring adjudication is described.
If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- Not applicable. This document pertains to Rigid Gas Permeable Contact Lenses, not an AI-assisted diagnostic or interpretive device.
If a standalone (i.e. algorithm only without human-in-the loop performance) was done:
- Not applicable. This is a contact lens, not an algorithm.
The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- Not applicable. The "ground truth" here is the established safety and effectiveness of the predicate devices based on their approved indications and material properties.
The sample size for the training set:
- Not applicable. No new development of an algorithm or device requiring a training set is described.
How the ground truth for the training set was established:
- Not applicable. See point 7.

In summary, this 510(k) submission primarily leverages the concept of substantial equivalence. The manufacturer argues that the Boston XO and XO2 Scleral Lenses have similar actions, technological characteristics, and present the same risks and benefits as the specified predicate devices (BostonSight PD Prosthetic Device and Boston Scleral Lens) when used for the expanded indications. Therefore, new performance data was not deemed necessary for this particular submission, which focuses on labeling revisions for existing materials.

Summary

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Image /page/0/Picture/2 description: The image is a seal for the Department of Health & Human Services - USA. The seal is circular with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" around the perimeter. In the center of the seal is an image of three faces in profile, stacked on top of each other.

Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002

July 17, 2017

BAUSCH + LOMB Incorporated % Ellen M. Beucler Vice President Foresight Regulatory Strategies, Inc. 187 Ballardvale Street, Suite A250 Wilmington, MA 01887

Re: K171404

Trade/Device Name: BOSTON XO® (hexafocon A), BOSTON XO2® (hexafocon B) Regulation Number: 21 CFR 886.5916 Regulation Name: Rigid Gas Permeable Contact Lens Regulatory Class: Class II Product Code: HOD Dated: May 10, 2017 Received: May 12, 2017

Dear Ellen M. Beucler:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

{1}------------------------------------------------

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting (reporting of medical devicerelated adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address

http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to

http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.

You may obtain other general information on your responsibilities under the Act from the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address

http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.

Sincerely yours,

Denise L. Hampton -S

for Malvina B. Eydelman, M.D. Director Division of Ophthalmic and Ear, Nose and Throat Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known) K171404

Device Name

BOSTON XO® (hexafocon A) Rigid Gas Permeable Contact Lens

Indications for Use (Describe)

Furthermore, eyes suffering from certain ocular surface disorders may benefit from the physical protection, aqueous hydrated environment and the saline bath provided by scleral lens designs.

Boston XO Scleral Lens designs for daily wear are indicated for therapeutic use for the management of irregular and distorted corneal surfaces where the subject:

1. cannot be adequately corrected with spectacle lenses
1. requires a rigid gas permeable contact lens surface to improve vision
1. is unable to wear a corneal rigid gas permeable lens due to corneal distortion or surface irregularities

Common causes of corneal distortion include but are not limited to corneal infections as a result of scar formation secondary to refractive surgery (e.g. LASIK or radial keratotomy) or corneal transplantation. Causes may also include corneal degeneration (e.g. keratoglobus, pellucid marginal degeneration, Salzmann's nodular degeneration) and corneal dystrophy (e.g., lattice dystrophy, granular corneal dystrophy, Reis-Bucklers dystrophy, Cogan's dystrophy).

The Boston XO Scleral Lens designs for daily wear are also indicated for therapeutic use in eyes with ocular surface disease (e.g. ocular Graft-versus-Host disease, Sjögren's syndrome, dry eye syndrome and Filamentary Keratitis), limbal stem cell deficiency (e.g. Stevens-Johnson syndrome, chemical radiation and thermal burns), disorders of the skin (e.g. atopy, ectodermal dysplasia), neurotrophic keratitis (e.g. Herpes zoster, Familial Dysautonomia), and corneal exposure (e.g. anatomic, paralytic) that might benefit from the presence of an expanded tear reservoir and protection against an adverse environment. When prescribed for therapeutic use for a distorted cornea or ocular surface disease, the Boston Scleral Lenses may concurrently provide correction of refractive error.

The lenses may be disinfected using a chemical disinfection (not heat) system only.

Type of Use (Select one or both, as applicable)

X Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

CONTINUE ON A SEPARATE PAGE IF NEEDED.

{3}------------------------------------------------

This section applies only to requirements of the Paperwork Reduction Act of 1995.

DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.

The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to:

Department of Health and Human Services Food and Drug Administration Office of Chief Information Officer Paperwork Reduction Act (PRA) Staff PRAStaff@fda.hhs.gov

"An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number."

{4}------------------------------------------------

Indications for Use

510(k) Number (if known) K171404

Device Name

BOSTON XO2® (hexafocon B) Rigid Gas Permeable Contact Lens

Indications for Use (Describe)

BOSTON XO2 Contact Lenses are also indicated for daily wear in an orthokeratology fitting program for the temporary reduction of myopia of up to 5.00 diopters in non-diseased eyes. Note: To maintain the orthokeratology effect of myopia reduction, lens wear must be continued on a prescribed wearing schedule.

Furthermore, eyes suffering from certain ocular surface disorders may benefit from the physical protection, aqueous hydrated environment and the saline bath provided by scleral lens designs.

Boston XO2 Scleral Contact Lens designs for daily wear are indicated for therapeutic use for the management of irregular and distorted corneal surfaces where the subject:

1. cannot be adequately corrected with spectacle lenses
1. requires a rigid gas permeable contact lens surface to improve vision
1. is unable to wear a corneal rigid gas permeable lens due to corneal distortion or surface irregularities

Common causes of corneal distortion include but are not limited to corneal infections, trauma, tractions as a result of scar formation secondary to refractive surgery (e.g. LASIK or radial keratotomy) or corneal transplantation. Causes may also include corneal degeneration (e.g. keratoglobus, pellucid marginal degeneration, Salzmann's nodular degeneration) and corneal dystrophy (e.g., lattice dystrophy, granular corneal dystrophy, Reis-Bucklers dystrophy, Cogan's dystrophy).

The Boston XO2 Scleral Lens designs for daily wear are also indicated for therapeutic use in eyes with ocular surface disease (e.g. ocular Graft-versus-Host disease, Sjögren's syndrome and Filamentary Keratitis), limbal stem cell deficiency (e.g. Stevens-Johnson syndrome, chemical radiation and thermal burns), disorders of the skin (e.g. atopy, ectodermal dysplasia), neurotrophic keratitis (e.g. Herpes zoster, Familial Dysautonomia), and corneal exposure (e.g. anatomic, paralytic) that might benefit from the presence of an expanded tear reservoir and protection against an adverse environment. When prescribed for therapeutic use for a distorted cornea or ocular surface disease, the Boston Scleral Lenses may concurrently provide correction of refractive error.

The lenses may be disinfected using a chemical disinfection (not heat) system only.

Type of Use (Select one or both, as applicable)

X Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

CONTINUE ON A SEPARATE PAGE IF NEEDED.

{5}------------------------------------------------

This section applies only to requirements of the Paperwork Reduction Act of 1995.

DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.

Department of Health and Human Services Food and Drug Administration Office of Chief Information Officer Paperwork Reduction Act (PRA) Staff PRAStaff@fda.hhs.gov

"An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number."

{6}------------------------------------------------

510(k) Summary

1. Applicant Information

Bausch + Lomb Inc. 1400 North Goodman Street Rochester, NY 14609 USA

Contact:	Glenn Davies, O.D.Senior Director Regulatory Affairs
Phone:	(585) 338-8215
Fax:	(585) 338-0702
email:	glenndavies@bausch.com
Date Prepared:	July 11, 2017

2. Device Information

Classification name:	Rigid Gas Permeable Contact Lens
Device classification:	Class II
Regulation number:	21 CFR 886.5916 (Rigid Gas Permeable Contact Lenses)
Product code:	HQD
Proprietary name:	Boston XO® (hexafocon A) and Boston XO2®(hexafocon B) Rigid Gas Permeable Contact Lens

3. Predicate Devices

Bausch + Lomb Inc. claims substantial equivalence to Boston Scleral Contact Lens, PMA No. P860022/S40 approved March 1, 1994 and BostonSight PD Prosthetic Device cleared in K161461 on July 25, 2016.

4. Description of Device

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5. Indications for Use

Boston XO (hexafocon A) and Boston XO2 (hexafocon B) Contact Lenses are indicated for daily wear for the correction of refractive ametropia (myopia, hyperopia, astigmatism and presbyopia) in aphakic and non aphakic persons with non-diseased eyes. Also, the lenses may be prescribed in otherwise non-diseased eyes that require a rigid contact lens for the management of irregular corneal conditions such as keratoconus, pellucid marginal degeneration, or following penetrating keratoplasty or refractive (e.g. LASIK surgery).

The Boston XO2 (hexafocon B) Contact Lenses are also indicated for daily wear in an orthokeratology fitting program for the temporary reduction of myopia of up to 5.00 diopters in non-diseased eyes. Note: To maintain the orthokeratology effect of myopia reduction, lens wear must be continued on a prescribed wearing schedule.

Furthermore, eyes suffering from certain ocular surface disorders may benefit from the physical protection, aqueous hydrated environment and the saline bath provided by scleral lens designs.

The Boston XO and XO2 Scleral Lens designs for daily wear are indicated for therapeutic use for the management of irregular and distorted corneal surfaces where the subject:

1. cannot be adequately corrected with spectacle lenses
1. requires a rigid gas permeable contact lens surface to improve vision
1. is unable to wear a corneal rigid gas permeable lens due to corneal distortion or surface irregularities

Common causes of corneal distortion include but are not limited to corneal infections, trauma, tractions as a result of scar formation secondary to refractive surgery (e.g. LASIK or radial keratotomy) or corneal transplantation. Causes may also include corneal degeneration (e.g. keratoconus, keratoglobus, pellucid marginal degeneration, Salzmann's nodular degeneration) and corneal dystrophy (e.g., lattice dystrophy, granular corneal dystrophy, Reis-Bucklers dystrophy, Cogan's dystrophy).

{8}------------------------------------------------

5. Indications for Use (continued)

The Boston XO and XO2 Scleral Lens designs for daily wear are also indicated for therapeutic use in eyes with ocular surface disease (e.g. ocular Graft-versus-Host disease, Sjögren's syndrome, dry eye syndrome and Filamentary Keratitis), limbal stem cell deficiency (e.g. Stevens-Johnson syndrome, chemical radiation and thermal burns), disorders of the skin (e.g. atopy, ectodermal dysplasia), neurotrophic keratitis (e.g. Herpes simplex, Herpes zoster, Familial Dysautonomia), and corneal exposure (e.g. anatomic, paralytic) that might benefit from the presence of an expanded tear reservoir and protection against an adverse environment.

When prescribed for therapeutic use for a distorted cornea or ocular surface disease, the Boston Scleral Lenses may concurrently provide correction of refractive error.

The lenses may be disinfected using a chemical disinfection (not heat) system only.

6. Performance Data

There are no changes to the Boston XO (hexafocon A) and Boston XO2 (hexafocon B) Rigid Gas Permeable contact lens material or lens designs as part of this application. These materials have been previously cleared for scleral lens designs. This application is for labeling revisions. No performance data is required.

7. Substantial Equivalence

In support of the expanded indications for Boston XO and XO2 to include scleral lens indications the following statements apply.

Boston XO and XO2 Rigid Gas Permeable Scleral Contact Lenses are fluoro silicone acrylate contact lenses that use similar actions and technological characteristics as the predicate devices (see Table 1 and Table 2).
. The Boston XO and XO2 Rigid Gas Permeable Scleral Lenses present the same risks and benefits as the predicate devices and are as safe and effective as the predicate devices when used according to the labeled directions for use and requested indications.

Therefore, the Boston XO and XO2 Rigid Gas Permeable Scleral Lenses are substantially equivalent to the BostonSight PD Prosthetic Device and the Boston Scleral Contact Lens.

{9}------------------------------------------------

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	Boston XO & XO2 Scleral Lens(hexafocon A and hexafocon B)	BostonSight PDProsthetic Device(oprifocon A)	Boston Scleral Lens(oprifocon A)
	K171404	K161461	P860022/S040
	Subject Device	Predicate Device	Predicate Device
Indication for Use	BOSTON XO (hexafocon A) and XO2® (hexafocon B) Contact Lenses are indicated for daily wear for thecorrection of refractive ametropia (myopia, hyperopia, astigmatism and presbyopia) in aphakic and nonaphakic persons with non-diseased eyes. Also, the lenses may be prescribed in otherwise non-diseased eyesthat require a rigid contact lens for the management of irregular corneal conditions such as keratoconus,pellucid marginal degeneration, or following penetrating keratoplasty or refractive (e.g. LASIK surgery).BOSTON XO2 Contact Lenses are also indicated for daily wear in an orthokeratology fitting program for thetemporary reduction of myopia of up to 5.00 diopters in non-diseased eyes. Note: To maintain theorthokeratology effect of myopia reduction, lens wear must be continued on a prescribed wearing schedule.Furthermore, eyes suffering fromcertain ocular surface disorders may benefit fromthe physical protection,aqueous hydrated environment and the saline bath provided by scleral lens designs.Boston Xo and XO2 Scleral Contact Lens designs for daily wear are indicated for therapeutic use for themanagement of irregular and distorted corneal surfaces where the subject:1. cannot be adequately corrected with spectacle lenses2. requires a rigid gas permeable contact lens surface to improve vision3. is unable to wear a comeal rigid gas permeable lens due to corneal distortion or surface irregularitiesCommon causes of corneal distortion include but are not limited to comeal infections, trauma, tractions as aresult of scar formation secondary to refractive surgery (e.g. LASIK or radial keratotomy) or comealtransplantation. Causes may also include corneal degeneration (e.g. keratoconus, keratoglobus, pellucidmarginal degeneration, Salzmann's nodular degeneration) and corneal dystrophy (e.g., lattice dystrophy,granular comeal dystrophy, Reis-Bucklers dystrophy, Cogan's dystrophy). The Boston XO and XO2 ScleralLens designs for daily wear are also indicated for therapeutic use in eyes with ocular surface disease (e.g.ocular Graft-versus-Host disease, Sjögren's syndrome, dry eye syndrome and Filamentary Keratitis), limbalstemcell deficiency (e.g. Stevens-Johnson syndrome, chemical radiation and thermal bums), disorders of theskin (e.g. atopy, ectodermal dysplasia), neurotrophic keratitis (e.g. Herpes simplex, Herpes zoster, FamilialDysautonomia), and corneal exposure (e.g. anatomic, paralytic) that might benefit fromthe presence of anexpanded tear reservoir and protection against an adverse environment. When prescribed for therapeutic usefor a distorted comea or ocular surface disease, the Boston Scleral Lenses may concurrently providecorrection of refractive erroг.lenses may be disinfected using a chemical disinfection (not heat) system only.
Actions/OperationalPrinciples	When placed on the eye the Rigid Gas Permeable Contact Lens acts as arefracting mediumto focus light rays on the retina to improve visual acuity.	Indicated for therapeutic use in eyes withocular surface disease from dry eye (e.g. ocularGraft-versus-Host disease, Sjögren'ssyndrome, dry eye syndrome), limbal stem celldeficiency (e.g.Stevens-Johnson syndrome,chemical and thermal burns, radiation),disorders of the skin (e.g. atopy, ectodermaldysplasia), neurotrophic keratitis (e.g. Herpessimplex, Herpes zoster, Familial Dysautonomia),and corneal exposure (e.g. anatomic, paralytic)that might benefit from the presence of anexpanded tear reservoir and protection againstan adverse environment. When prescribed fortherapeutic use for distorted cornea or ocularsurface disease, the BostonSight PD ProstheticDevice may incidentally provide correction ofrefractive erroг.When placed on the eye the Rigid GasPermeable Contact Lens acts as a refractingmedium to focus light rays on the retina toimprove visual acuity.	Indicated for eyes having significantly reducedvision due to the presence of a distortedcomeal surface that:1) precludes satisfactory spectacle lenscorrection 2) demonstrates significantlyimproved rigid contact lens corrected vision 3)is incapable of wearing traditional corneallenses because of the inability to achieveadequate lens centration/stability and/ortolerance to physical contact with a lens.Furthermore, eyes suffering from certain ocularsurface disorders may benefit from the physicalprotection and the saline bath provided by ascleral lens.When placed on the eye the Rigid GasPermeable Contact Lens acts as a refractingmedium to focus light rays on the retina toimprove visual acuity.
Product Code	HQD	HQD	HQD
Common name	Contact Lens, Rigid Gas Permeable	Contact Lens, Rigid Gas Permeable	Contact Lens, Rigid Gas Permeable
Device Class	II	II	II*
CFR Reference	21 CFR 886.5916	21 CFR 886.5916	21 CFR 886.5916
Production Method	Lathe Cut	Lathe cut	Lathe cut
FDA Group #	Group # 3 Fluom Silicone Acrylate	Group # 3 Fluoro Silicone Acrylate	Group # 3 Fluoro Silicone Acrylate
	Boston XO & XO2Contact LensK171404		BostonSight PDProsthetic Device(oprifocon A)	Boston Scleral Lens(oprifocon A)
			K161461	P860022/S040
	Subject Devices
	Boston XO(hexafocon A)	Boston XO 2(hexafocon B)	Predicate Device	Predicate Device
Refractive Index	1.415	1.424	1.423	1.423
Specific Gravity	1.27	1.19	1.24	1.24
Wetting Angle	49°	38°	56°	56°
Hardness	81	78	81	81
Modulus	1500 Mpa	1160 Mpa	1300 Mpa	1300 Mpa
Visible Light Transmittance	> 92%	> 95%	> 95%	> 95%
Tint*	Clear, Blue, Ice Blue,Violet, Green	Clear, Blue, Ice Blue,Violet, Green	Clear	Clear
Water Content	<1%	<1%	<1%	<1%
Oxygen Permeability**	100	141	85	85

{10}------------------------------------------------

Table 2 Substantial Equivalence - Physical Comparison

{x1011 (cm3 O2 • cm)/ (cm2 • sec • mmHg) @ 35° C}

**polarographic method (ISO/Fatt)

*Blue/Ice Blue Contains D&C Green No. 6

*Violet Contains D&C Violet No. 2

*Green Contains D&C Green No. 6

and C.I. Solvent Yellow No. 18

Regulation Number and Section

§ 886.5916 Rigid gas permeable contact lens.

(a)
Identification. A rigid gas permeable contact lens is a device intended to be worn directly against the cornea of the eye to correct vision conditions. The device is made of various materials, such as cellulose acetate butyrate, polyacrylate-silicone, or silicone elastomers, whose main polymer molecules generally do not absorb or attract water.(b)
Classification. (1) Class II if the device is intended for daily wear only.(2) Class III if the device is intended for extended wear.
(c)
Date PMA or notice of completion of a PDP is required. As of May 28, 1976, an approval under section 515 of the act is required before a device described in paragraph (b)(2) of this section may be commercially distributed. See § 886.3.