The CONTEX OK™ (siflufocon A) Rigid Gas Permeable Contact Lens for Orthokeratology is indicated for use in the reduction of myopic refractive error in non-diseased eyes. The lens is indicated for daily wear in an orthokeratology fitting program for the temporary reduction of myopia of up to 3.00 diopters. The lens may be disinfected using a chemical disinfection system only. Note: To maintain the orthokeratology effect of myopia reduction lens wear must be continued on a prescribed wearing schedule.

Device Description

The CONTEX OK™ (orthokeratology) contact lens is a rigid gas permeable contact lens in a reverse geometry design. The lens material siflufocon A, is a fluoro silicone acrylate polymer which contains D & C Green #6 as a color additive. The CONTEX OK™ (orthokeratology) contact lens has the following dimensions: Chord Diameter................Approximately 6.5 to 13.0 mm Center Thickness for Low Minus Lens..................................0.10 to 0.30 mm for Plus Lens:........................................0.20 to 0.70 mm Base Curve........................................6.50 to 11.00 mm Secondary Curves........................ 0.1 to 2 mm. Flatter or Steeper than Base Curve Peripheral Curves........................ 0.1 to 2 mm. Flatter or Steeper than Base Curve Powers........................................-10.00 to +5.00 Diopters Aspheric Lens Eccentricity ................................................................................................................................................... (Oblate, Prolate or Tangent Conic) The physical properties of the lens are: Refractive Index...... 1.43 (Nd at 25°) Light Transmittance... > 92.5% (370-760 nm) Wetting Angle ... 24.0 (Contact Receding Angle) Specific Gravity.... 1.25 Hardness.... 82 Water Content... <1% Oxygen Permeability.....(cm²/sec) (ml O₂ x Hg) 81 x10⁻¹¹Dk at 35°C CONTEX OK™ (orthokeratology) contact lenses produce a temporary reduction of myopia by changing the shape (flattening) of the cornea, which is elastic in nature. Flattening the cornea reduces the focusing power of the eye, and if the amount of corneal flattening is properly controlled, it is possible to bring the eye into correct focus and compensate for myopia. Contact lenses rest directly on the corneal tear layer and can influence the corneal shape. After the contact lens is removed, the cornea retains its altered shape for part or all of the remainder of the day. A retainer lens must be used each day to maintain the corneal flattening, or the myopia will revert back to the pre-treatment level.

AI/ML Overview

This document describes an orthokeratology contact lens (CONTEX OK™) intended for the temporary reduction of myopia. Below is an analysis of its acceptance criteria and the study performed.

1. Table of Acceptance Criteria (Implied) and Reported Device Performance

The acceptance criteria are implied through the intended use and the clinical study results, as no explicit numerical acceptance targets are stated. The device is shown to be effective if it can achieve a temporary reduction in myopic refractive error.

Acceptance Criteria (Implied from Intended Use)	Reported Device Performance
Safety: Minimal adverse reactions and slit-lamp findings.	Adverse Reactions: No eyes experienced adverse reactions, slit-lamp findings requiring treatment, or symptoms/problems/complaints requiring treatment. Slit-Lamp Findings: 188 reports of Grade 1 findings (6 edema, 108 staining, 24 injection, 50 tarsal abnormality). No Grade 2 or higher findings. Findings reduced in incidence over time. Symptoms/Complaints: 425 reports, largest being blur following lens wear (20.2%) and variable vision (17.2%) due to corneal changes; other complaints consistent with RGP lenses.
Effectiveness: Temporary reduction of myopic refractive error up to 3.00 diopters.	Refractive Power Reduction: - Average reduction: 1.69 diopters (range 0.25 to 4.25 D). - 32% of eyes had 0.25-1.00 D reduction. - 32% of eyes had 1.25-2.00 D reduction. - 23% of eyes had 2.25-3.00 D reduction. - 9% of eyes had 3.25-4.00 D reduction. - 1% of eyes had 4.25 D reduction. - 106 out of 110 eyes showed some reduction. - Limit for full reduction to emmetropia: -3.50 diopters. - For initial myopia >3.75D, average reduction was 2.75D.
Visual Acuity Improvement:	Uncorrected Visual Acuity (Final Visit): - 39% of eyes achieved 20/20 or better. - 71% of eyes achieved 20/40 or better. Visual Acuity with contact lenses (Final Visit): - 99 eyes (90%) 20/20 or better - 109 eyes (99%) 20/40 or better - 1 eye 20/70. - Some eyes experienced 1-3 line drops in visual acuity, attributed to residual astigmatism.
Corneal Flattening (Keratometry):	Keratometry: - 89% of eye meridians flattened. - Average flattening: 1.17 diopters. - Greatest flattening: 4.13 diopters. - Corneal astigmatism change: 8% no change, 32% decrease <1D, 41% increase <1D, 16% increase >1D.

2. Sample Size Used for the Test Set and the Data Provenance

Sample Size (Test Set): 138 eyes were initially enrolled, with 136 eyes dispensed contact lenses. 110 eyes completed a minimum of three months of contact lens wear. The performance data is generally reported on these 110 eyes that completed the study.
Data Provenance: The document does not explicitly state the country of origin. It describes a "Preclinical Studies: Described in the original 510 (k) submission K941883" and "Clinical Studies" for the K9736097 submission, suggesting the data is part of the regulatory submission for the United States. The study appears to be prospective clinical trial, observing patients over a three-month period.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and the Qualifications of Those Experts

The document does not provide information on the number or qualifications of experts used to establish a ground truth for the test set. Clinical studies concerning contact lenses typically rely on measurements taken by trained optometrists or ophthalmologists, but this information is not detailed here.

4. Adjudication Method for the Test Set

The document does not describe any specific adjudication method (e.g., 2+1, 3+1, none) for the test set data. Clinical measurements were likely taken by the participating clinicians.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This study is a clinical trial evaluating the safety and effectiveness of a medical device (contact lens) in patients, rather than an AI-assisted diagnostic tool.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done

No, a standalone (algorithm only) performance study was not done. This product is a physical medical device (contact lens), not an algorithm or AI system.

7. The Type of Ground Truth Used

The "ground truth" for evaluating the contact lens's performance was based on direct clinical measurements and observations of the patients using the device, including:

Refractive Power: Measured reduction in myopic refractive error (diopters).
Visual Acuity: Measured visual acuity (e.g., 20/20, 20/40).
Keratometry: Measured changes in corneal flattening (diopters).
Slit-Lamp Findings: Direct observation of ocular health.
Adverse Events/Symptoms/Complaints: Patient reported and clinically observed adverse effects.

8. The Sample Size for the Training Set

This product is a physical medical device (contact lens), not an AI algorithm. Therefore, there is no "training set" in the context of machine learning. The clinical study enrolled 138 eyes, with 110 eyes completing three months of wear. This would be considered the sample for evaluating the device's performance.

9. How the Ground Truth for the Training Set Was Established

As this is not an AI algorithm, there is no "training set" or "ground truth" for a training set in the machine learning sense. The clinical data collected from the 110 eyes that completed the study served as the evidence for safety and effectiveness.

Summary

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K9736097

APR - 8 1998

SUMMARY OF SAFETY AND EFFECTIVENESS K973697

CONTEX (siflufocon A) RIGID GAS PERMEABLE OK™ (ORTHOKERATOLOGY) CONTACT LENS

1. Submitted by :	Contex, Inc.4505 Van Nuys Blvd.Sherman Oaks, CA 91403
Contact :	NICK STOYAN, PRESIDENT

Contex, Inc. 4505 Van Nuys Blvd. Sherman Oaks, CA 91403 Phone 1-800-626-6839

March 17, 1998 Date prepared:

Device:

Common Name:	CONTEX OKTM (orthokeratology) contact lens
Trade Name:	CONTEX (siflufocon A) Rigid Gas Permeable OKTM (orthokeratology) Contact Lens
Classification	Class II (Performance Standards)21 CFR 886.5916Rigid gas permeable contact lens
3. Substantial equivalence	A claim of substantial equivalence is based on preamendment status in which a predicate lens of rigid contact lens material was labeled, promoted and distributed in interstate commerce for the same intended use before May 28, 1976.
4. Device description	The CONTEX OKTM (orthokeratology) contact lens is a rigid gas permeable contact lens in a reverse geometry design. The lens material siflufocon A, is a fluoro silicone acrylate polymer which contains D & C Green #6 as a color additive. The CONTEX OKTM (orthokeratology) contact lens has the following dimensions:
	Chord Diameter................Approximately 6.5 to 13.0 mmCenter Thicknessfor Low Minus Lens..................................0.10 to 0.30 mmfor Plus Lens:........................................0.20 to 0.70 mmBase Curve........................................6.50 to 11.00 mmSecondary Curves........................ 0.1 to 2 mm. Flatter or Steeper than Base CurvePeripheral Curves........................ 0.1 to 2 mm. Flatter or Steeper than Base CurvePowers........................................-10.00 to +5.00 Diopters

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Aspheric Lens Eccentricity ................................................................................................................................................... (Oblate, Prolate or Tangent Conic)

The physical properties of the lens are:

Refractive Index......	1.43 (Nd at 25°)
Light Transmittance...	> 92.5% (370-760 nm)
Wetting Angle ...	24.0
(Contact Receding Angle)
Specific Gravity....	1.25
Hardness....	82
Water Content...	<1%
Oxygen Permeability.....(cm²/sec) (ml O₂ x Hg)	81 x10⁻¹¹Dk at 35°C

CONTEX OK™ (orthokeratology) contact lenses produce a temporary reduction of myopia by changing the shape (flattening) of the cornea, which is elastic in nature. Flattening the cornea reduces the focusing power of the eye, and if the amount of corneal flattening is properly controlled, it is possible to bring the eye into correct focus and compensate for myopia. Contact lenses rest directly on the corneal tear layer and can influence the corneal shape. After the contact lens is removed, the cornea retains its altered shape for part or all of the remainder of the day. A retainer lens must be used each day to maintain the corneal flattening, or the myopia will revert back to the pre-treatment level.

5. Intended Use

CONTEX (siflufocon A) Rigid Gas Permeable OK™ (orthokeratology) contact lenses are indicated for use in the reduction of myopic refractive error in non-diseased eyes. The lens is indicated for daily wear in an orthokeratology fitting program for the temporary reduction of myopia of up to 3.00 diopters. The lens may be disinfected using a chemical disinfection system only. Note: To maintain the orthokeratology effect of myopia reduction lens wear must be continued on a prescribed wearing schedule.

6a. CONTEX OK™ (orthokeratology) contact lenses have the same technological characteristics as the predicate device, which is designed to purposely flatten the shape of the cornea by applying slight pressure to the center of the cornea. If the cornea is flattened this reduces the focusing power of the eye, and if the amount of corneal flattening is sufficient, it is possible to bring the eye into correct focus and compensate for myopia.
6b1. Preclinical Studies: Described in the original 510 (k) submission K941883

6b2. Clinical Studies

A total of 138 eyes were enrolled in this investigation and accounted for, with 136 eyes dispensed contact lenses. A total of 110 eyes completed a minimum of three months

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of contact lens wear, 12 eyes were incomplete and 16 eyes were discontinued. A large portion of the patients in this study (49.1%) had previous contact lens wearing experience, with the remainder consisting of new wearers.

ADVERSE REACTIONS

There were no eyes that experienced adverse reactions, slit lamp finidngs requiring treatment or symptoms, problems and complaints requiring treatment.

SLIT-LAMP FINDINGS

There were a total of 188 reports of grade 1 slit-lamp findings during the three-month course of this study including 6 for edema, 108 for staining, 24 for injection, and 50 for tarsal abnormality. There were no reports of slit-lamp findings of Grade 2 or higher. There were no reports of any slit lamp findings for Vascularization or Other conditions. The total number of slit-lamp findings was within expected limits for an RGP contact lens. The large number of reports for Tarsal Abnormalities can be attributed to the group of soft lens wearers that entered the study. All finding reduced in incidence over time.

SYMPTOMS, PROBLEMS, AND COMPLAINTS

There were a total of 425 reports of symptoms, problems or complaints during the threemonth course of this study. The largest number of complaints (20.2%) was for blur following lens wear. This occurred because very often the lens caused some corneal flattening but it was not sufficient to correct for the patient's refractive error. The next largest number of complaints (17.2%) was for Variable Vision, which occurred because of corneal changes after lens removal. The high incidence of symptoms related to blur following lens wear can be attributed to the expected condition for orthokeratology, especially in the early wearing period, when the cornea is undergoing change. Other complaints were consistent with those found generally for wearers of RGP contact lenses.

KERATOMETRY

Most eye meridians (89%) flattened during the three-month period of this study. The average flattening was 1.17 diopters and the greatest flattening was 4.13 diopters. Of the 110 eyes (55 patients) which completed the three month clinical, 8% showed no change in corneal astigmatism. 32% showed a decrease less than one diopter, while 41% showed an increase less than one diopter and 16% showed an increase greater than one diopter.

It has been pointed out in several studies of keratometry that the change in corneal flattening from orthokeratology, as measured in keratometer diopters, is generally less than the change in refractive power which results in a reduction in myopia. This is generally attributed to keratometer error due to the separation of the mires being outside of the central corneal area.

REFRACTIVE POWER

A total of 106 eyes showed some reduction in myopic refractive error during the 3-month time period that the CONTEX OK™ (orthokeratology) contact lenses were worn. The average reduction was 1.69 diopters with a range from 0.25 to 4.25 diopters. This included 35

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eyes (32%) with a reduction of between 0.25 and 1.00 D., 35 eyes (32%) between 1.25 and 2.00 D., 25 eyes (23%) between 2.25 and 3.00 D., 10 eyes (9%) between 3.25 and 4.00 D. and one eye (1%) reduced by 4.25 D. One eye had no change and 3 eyes increased in minus power by 0.25 D. The average reduction in refractive power was 1.69 and the median was 1.63. The reduction in myopia was greater for eyes with a higher initial refractive error. No eyes over -3.50 diopters were able to achieve a full reduction in myopia. For eyes with an initial myopia of greater than 3.75 diopters the average final exam reduction in myopia was 2.75 diopters. The limit in initial myopia that could be reduced to emmetropia in some eyes was -3.50 diopters.

The average amount of myopia reduction is shown in the following table:

AVERAGE REDUCTION IN MYOPIA (M)

INITIAL	REDUCTION
Myonia	Myonia

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There was an insignificant difference between the patients who wore contact lenses prior to the study and those with no previous contact lens experience. The percentage of patients that achieved full or partial temporary refractive reduction is shown in the following table.

PERCENT OF EYES THAT ACHIEVED FULL OR PARTIAL TEMPORARY REDUCTION OF MYOPIA

INITIALMYOPIA	FULLTEMPORARYREDUCTION	UP TO 0.50 D.UNDER FULLREDUCTION	FINAL V.A.20/20 or better	FINAL V.A.20/40 or better
≤1.00 D	52%	84%	78%	100%
-1.25 to- 2.00 D.	36%	55%	74%	96%
-2.25 to- 3.00 D.	18%	35%	48%	72%
-3.25 to- 4.00 D.	4%	13%	16%	64%

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VISUAL ACUITY

For the patients (110 eyes) that completed this study, the initial visual acuity by best refraction was 20/20 or better for 104 eyes and 20/40 or better for all eyes (110). At the final visit, visual acuity with contact lenses was equal to or better than 20/20 for 99 eyes, 20/40 for 109 eyes and one eye had a visual acuity of 20/70. Nine eyes had a one-line drop in visual acuity for contact lenses compared to best refraction, one eye had a two-line drop and three eyes had a three-line drop. In each case the reduced visual acuity was attributed to residual astigmatism when wearing contact lenses.

The percentage of eyes that achieved uncorrected visual acuity of 20/20 or better and 20/40 or better in relation to the initial myopia is given in the above table. A total of 43 (39%) eyes achieved a visual acuity of 20/20 or better and 78 (71%) eyes achieved 20/40 or better. The study did not report how long improved vision lasted after lenses were removed.

WEARING TIME

The average wearing time required for patients who wore CONTEX OK™ (orthokeratology) contact lenses for various time periods was as follows:

One week	7.7 hours
Two weeks	7.8 hours
One month	8.0 hours
Three months	8.4 hours

There was considerable variability, however, as many patients required several hours more or less than the averages as shown for the three-month time period as follows:

Time Worn	Percent of patient
0 to 4 hours	25.5%
4.1 to 8 hours	21.8%
8.1 to 12 hours	23.7%
12.1 to 16 hours	27.2%

LENS REPLACEMENTS

A total of 217 lenses were replaced over the three-month period of this study. The largest number of replacements were for visual acuity (62) and base curve (142). This is a larger number of lenses replaced than would be expected for a regular RGP lens. but not for the orthokeratology lens of this study. A large number of lens replacements is expected to achieve the desired fitting relationship with the lens base curve as the cornea flattens.

6b3. Safety and Effectiveness

The device is safe as demonstrated by the minimal incidence of signs and symptoms and the lack of any adverse reactions during the course of the clinical studies.

The device is effective as demonstrated by the temporary improvement in visual acuity and reduction in myopia as claimed.

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Image /page/5/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a circular border with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" arranged around it. Inside the circle is a stylized eagle symbol, with three curved lines representing the eagle's wings and body.

Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850

APR - 8 1998

Nick Stoyan President CONTEX, INC. 4505 Van Nuys Blvd. Sherman Oaks, CA 91403

Re: K973697

Trade Name: CONTEX OK ™ (siflufocon A) Rigid Gas Permaeble Contact Lens for Orthokeratology Regulatory Class: II Product Code: 86 HQD Dated: March 9, 1998 Received: March 10, 1998

Dear Mr. Stoyan:

We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to 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). 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.

If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the Current Good Manufacturing Practice requirements, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic QS inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. In addition, FDA may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or regulations.

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Page 2 - Mr. Nick Stoyan

This letter will allow you to begin marketing your device as described in your 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4613. Additionally, for questions on.the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html".

Sincerely yours,

A. Ralph Rosenthal

A. Ralph Rosenthal, M.D. Director Division of Ophthalmic Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Page 1 of 1 _

510(k) Number (if known): K973697

Device Name: CONTEX OK™ (siflufocon A) Rigid Gas Permaeble Contact Lens for Orthokeratology

The CONTEX OK™ (siflufocon A) Rigid Gas Permaeble Contact Lens for Orthokeratology is indicated for use in the reduction of myopic refractive error in non-diseased eyes. The lens is indicated for daily wear in an orthokeratology fitting program for the temporary reduction of myopia of up to 3.00 diopters. The lens may be disinfected using a chemical disinfection system only.

Note: To maintain the orthokeratology effect of myopia reduction lens wear must be continued on a prescribed wearing schedule.

(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of Device Evaluation (ODE)

Orzetta

(Division Sign-Off) Division of Ophthalmic Devices 1973697 510(k) Number_

Prescription Use (Per 21 CFR 801.109) OR

Over-The-Counter Use

(Optional Format 1-2-96)

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.