Patient Information Booklet (Part 1) For Potential Users of Rigid Gas Permeable Contact Lenses for Orthokeratology
Trade Name (generic name)
RIGID GAS PERMEABLE CONTACT LENSES FOR ORTHOKERATOLOGY for
[Daily Wear][Overnight Wear]
|CAUTION:||Federal law prohibits dispensing without a prescription.|
|WARNING:||Contains a [identify] compound which harms public health and environment by destroying ozone in the upper atmosphere.|
TABLE OF CONTENTS
How the Eye Functions
How TN (generic name) Rigid Gas Permeable Contact Lenses
for Orthokeratology Function
Alternative Ways To Correct Nearsightedness
Clinical Study Data
Maintaining Effects of TN Contact Lens for Orthokeratology Myopic Reduction
Maintenance Lens or Retainer Lens Wear
Wearing Restrictions And Indications
Adnexa: Tissues near the eye.
Adverse effects: Undesirable effects.
Aphakia: Eye that does not have a lens structure.
Astigmatism: Eye condition in which one or more surfaces of the cornea or lens has a shape that is not round but more like that of a spoon.
Contact Lens Sticking: Lack of movement of a contact lens on the cornea.
Cornea: The clear, bubble-like structure on the front of the eye, where light first enters the eye.
Corneal abrasion: Loss of cells on the corneal surface due to mechanical trauma.
Corneal edema: Accumulation of fluid in the cornea.
Corneal hypoesthesia: Partial loss of sensitivity to touch in the cornea.
Corneal staining: Bright areas on the cornea where dye collects and which indicates an abrasion or other disturbance of the cornea.
Corneal ulcer: small area of tissue loss in the cornea.
Disinfection: Destruction of bacteria and viruses but not some spores.
Diopter: Unit of power for glasses or contact lenses.
Enzyming contact lenses: Placing contact lenses in a solution that contains an enzyme that dissolves proteins on the surface of the lens.
Hypoesthesia: Reduced corneal sensitivity to touch.
Iritis: Infection of the iris or colored portion of the eye.
Lacrimal secretion: Tearing.
Myopia: Medical term for nearsightedness.
Myopic Reduction Maintenance Lens: A modification of the orthokeratology contact lens design in which the central portion of the lens applies just enough pressure to the cornea to maintain the corneal flattening achieved but with no additional corneal flattening.
Neovascularization: New vessel growth in the cornea.
Orthokeratology: Contact lens fitting procedure that temporarily reduces nearsightedness after contact lenses have been removed.
Refract: Bending of light in order to make it focus.
Refractive anomalies: Eye conditions leading to blurred vision including nearsightedness, farsightedness and astigmatism.
Retainer Lenses: Another name for the Myopic Reduction Maintenance Lens.
Retina: Structure at the back of the eye that receives the light image.
Rewetting contact lenses: Placing a solution in the eye while contact lenses are worn that acts as an artificial tear to wet the lens.
Sticking lens: Lens on the cornea that does not move.
The information in this booklet is to help you decide whether or not to be fitted with the TN contact lenses for orthokeratology. Orthokeratology is a contact lens fitting procedure that temporarily reduces nearsightedness (known by the medical name of myopia) after contact lenses have been removed. By temporary it is meant that the contact lenses are worn for a portion of the [day] [night] and then removed, whereupon the nearsightedness remains reduced for all or part of the remainder of the day. The exact time period over which the myopia remains reduced varies with each patient. Generally, TN contact lenses for orthokeratology should be worn for part of each day for the orthokeratology effect to continue.
The eye is very much like a camera and must be in good focus to see objects clearly. The focusing power of the eye comes from two eye structures, the cornea and the lens [(Figure 1)]. The cornea is the clear, bubble-like structure on the front of the eye, where light first enters the eye. It provides about two thirds of the eye's focusing power, and the lens inside the eye provides the other third. In a normal eye light focuses at the retina, at the back of the eye, which acts like the film in a camera. Some eyes focus, or refract, the light too much, so that the images of distant objects are formed in front of the retina, and the image on the retina is blurred, producing myopia [(Figure 2)].
Myopia usually starts in childhood and gets progressively worse through adolescence. It normally stops increasing by the late teens, but it can sometimes continue to get worse into the mid-twenties.
TN contact lenses for orthokeratology produce a temporary reduction of nearsightedness by changing the shape (flattening) of the cornea, which is elastic in nature. Contact lenses rest directly on the cornea, separated only by a layer of tears, and can influence the corneal shape. Regular contact lenses are designed to nearly match the shape of the cornea and thereby cause little or no flattening effect but TN contact lenses for orthokeratology are designed to purposely not match the shape of the cornea but instead apply slight pressure to the center of the cornea [(Figure 3)], in a design known as reverse geometry. Pressure is produced when the lens is less curved than the cornea, which places more of the lens weight on 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 [(Figure 4)]. After the lens is removed, the cornea retains its altered shape for all or part of the remainder of the day.
TN contact lenses for orthokeratology are indicated for patients who desire to have time periods during the day in which they do not need to wear their contact lenses, but still be able to see clearly. This might include such activities as swimming and other sports. TN contact lenses for orthokeratology may be indicated in occupations that require exposure to smoke, noxious gases or conditions of low humidity, such as might occur, for example, for flight attendants, in which case their contact lenses can be removed without interference with vision. Some patients are content to wear their contact lenses for normal activities during part of the day and remove them for evening activities.
Nearsightedness (myopia) can be corrected by any method that reduces the focusing power of the eye. The most common methods of reduction are by glasses or regular contact lenses. These represent a means of correcting myopia only during the time that the glasses or regular contact lenses are worn, with no lasting effect on the myopia. Other methods of correcting myopia involve various surgical procedures. These involve techniques to reshape the cornea so that it is flattened in a way that is similar to that produced by TN contact lenses for orthokeratology, except that the surgical procedures are permanent.
TN contact lenses for orthokeratology may produce a temporary reduction of all or part of your myopia. The amount of reduction will depend on many factors, including the amount of your initial myopia, the elastic characteristics of your eye and the way that your contact lens fits on your eye.
[Summary example] A total of # (# patients) eyes were enrolled in a pre-marketing clinical study. Of those enrolled, # eyes (# patients) completed a minimum of [three][twelve] months of contact lens wear. Of the completed eyes a total of # eyes showed some reduction in myopic refractive error during the  -month time period that the TN contact lenses for orthokeratology were worn. The average reduction was # diopters with a range from # to # diopters.
The average amount of myopia that can be expected to be corrected is shown in the following table. These values are only averages and some patients can be expected to achieve more or less than these averages.
AVERAGE REDUCTION IN MYOPIA (Diopters)
[Summary of data]
TN contact lenses for orthokeratology provided a temporary full reduction in some patients with up to # diopters of myopia. For patients with greater than # diopters of myopia only a partial reduction of myopia can be expected. The percentage of patients that can be expected to achieve full or partial temporary refractive reduction is shown in the following table.
PERCENT OF EYES THAT ACHIEVED FULL OR PARTIAL
TEMPORARY REDUCTION OF MYOPIA
UP TO 0.50 D.
- 2.00 D.
- 3.00 D.
- 4.00 D.
The average wearing time required for patients who wore the TN contact lenses for orthokeratology was consistently about # [hours] [days] during the entire [three] [twelve] month study. The study [did] [did not] report how long the improved vision lasted once lenses were removed. [On average improved vision lasted about # hours.]
[Summarize the lens wearing time data.]
EFFECTS ON ASTIGMATISM
Either increases or decreases in astigmatism may occur following orthokeratology. Of the # eyes (# patients) which completed the [three] [twelve] month clinical study, #% showed no change in corneal astigmatism, #% showed a decrease less than one diopter, while #% showed an increase less than one diopter and #% showed an increase greater than one diopter.
The long-term wear of TN contact lenses for orthokeratology does not eliminate the need to continue wearing contact lenses to produce the orthokeratology effect. After the cornea has been flattened by wearing TN contact lenses for orthokeratology, new lenses are prescribed that are Myopic Reduction Maintenance Lenses or Retainer Lenses. Retainer Lenses are a modification of the patient's TN contact lens for orthokeratology design in which the central portion of the lens applies just enough pressure to the cornea to maintain the corneal flattening achieved but with no additional corneal flattening. The retainer lenses are generally worn for the same schedule as the TN contact lenses for orthokeratology and should be worn each day to maintain the orthokeratology effect.
[Studies have not been conducted to support the safety of wearing TN contact lenses for orthokeratology for overnight or extended wear.]
There is a small risk involved when any contact lens is worn. It is not expected that TN contact lenses for orthokeratology will provide a risk that is greater than other rigid gas permeable contact lenses.
The two most common side effects which occur in rigid contact lens wearers are corneal edema and corneal staining. It is anticipated that these two side effects will also occur in some wearers of TN contact lenses for orthokeratology. Other side effects which sometimes occur in all contact lens wearers are pain, redness, tearing, irritation, discharge, abrasion of the eye or distortion of vision. These are usually temporary conditions if the contact lenses are removed promptly and professional care is obtained.
In rare instances, there may occur permanent corneal scarring, decreased vision, infections of the eye, corneal ulcer, iritis, or neovascularization. The occurrence of these side effects should be minimized or completely eliminated if proper schedule of care is followed. You should remove your contact lenses if any abnormal signs are present. Never wear your contact lenses while in the presence of noxious substances. Be certain to return for all follow-up visits required by your eyecare practitioner.
TN contact lenses for orthokeratology are indicated for use in the reduction of myopic refractive error in non-diseased eyes. The lens is indicated for [daily wear][extended wear from X to X days between removals for cleaning and disinfection as recommended by the eye care practitioner] in an orthokeratology fitting program for the temporary reduction of myopia of up to # diopters. The lens may be disinfected using a chemical lens care system only.
|Note:||To maintain the orthokeratology effect of myopia reduction, lens wear should be continued on a prescribed wearing schedule.|
[Do Not Wear Your Lenses While Sleeping.]
CONTRAINDICATIONS (REASONS NOT TO USE)
DO NOT USE YOUR TN contact lenses for orthokeratology when any of the following conditions exist:
- Acute and subacute inflammations or infection of the anterior chamber of the eye.
- Any eye disease, injury, or abnormality that affects the cornea, conjunctiva or eyelids.
- Severe insufficiency of tears (dry eyes)
- Corneal hypoesthesia (reduced corneal sensitivity) if not aphakic.
- Any systemic disease which may affect the eye or be exacerbated by wearing contact lenses.
- Allergic reactions of ocular surfaces or adnexa which may be induced or exaggerated by wearing contact lenses or use of contact lens solutions.
- Allergy to any ingredient, such as mercury or Thimerosal, in a solution which is to be used to care for your TN contact lenses for orthokeratology.
- Any active corneal infection (bacterial, fungal or viral).
- If eyes become red or irritated
You should be advised of the following warnings pertaining to contact lens wear:
[Daily wear lenses are NOT indicated for overnight wear, and you should not wear lenses while sleeping. Clinical studies have shown that the risk of serious adverse reactions such as corneal infection or ulcers is increased when contact lenses are worn overnight.]
Problems with contact lenses and lens care products could result in serious injury to the eye. It is essential that you follow your eyecare practitioner's direction and all labeling instructions for proper use of lenses and lens care products, including the lens case. Eye problems, including corneal ulcers, can develop rapidly and lead to loss of vision.
Studies have shown that contact lens wearers who are smokers have a higher incidence of adverse reactions than nonsmokers.
If you experience eye discomfort, excessive tearing, vision changes, or redness of the eye you should immediately remove your lenses and promptly contact your eyecare practitioner.