What is Corneal Molding?
Corneal Molding (CM) is better known as Orthokeratology. It is a process of sleeping with specially designed corneal molds (fancy rigid gas permeable contact lenses) which change the curvature of the cornea. After waking, when the patient removes the lens they can see great all day WITH NOTHING IN THEIR EYES.
It can be enjoyed by people of all ages and those who have nearsightedness (myopia), farsightedness (hyperopia), astigmatism and the need for bifocals (presbyopia). A huge added benefit for the younger patient who suffers from continuing worsening of their vision (stronger glasses every year…) is this molding process stops, to significantly slows that progression. This, by itself, answers one of the greatest requests by parents: “How can I keep my child’s eyes from getting worse every year?”
- Put the corneal molds in your eyes before sleep
- Remove them after waking
- See great all day with nothing in your eyes
Corneal Molding (CM) is a non-surgical alternative to refractive surgery, yet has many advantages over refractive surgery (PRK, LASIK, LASEK, RK). Corneal Molding has no surgical risk, does not involve post operative pain, does not have the potential to leave hazy vision that can be experienced by patients following laser surgery, does not have the potential to cause an increase in dry eye syndrome, causes no damage to Bowman’s membrane (the tough protective layer just under the corneal surface), does not exclude children and, in fact, children make excellent candidates, can be done even if your vision is continuing to change, and is reversible. This reversibility gives two large advantages to corneal molding compared with surgery.
1. There’s no possibility of having a permanent bad result.
2. Since your eyes will continue to change even with a “perfect” surgical result, you will need prescription eyewear at some time in the future. To the contrary, CM can address these changes by simply updating the retainer lenses. As easily as updating a pair of glasses, your visual freedom is restored and maintained.
There are 3 main reasons why people should not pursue corneal molding.
- “Dr. says so” Simply put, Dr. Garretson will not direct anyone toward any procedure or choice which is not appropriate for that person, PERIOD. This principle applies to everything he does and offers. Reasons for poor candidacy include: excessive amounts of refractive error, unpredictable sleep hours, irregular corneal curvature, unrealistic expectations, etc.
- Cost. Overnight corneal reshaping has greater costs than traditional glasses or soft contact lenses but, those options do NOT offer what corneal molding provides. The fees are tiered because not all patients are the same. Some prescriptions are more complicated than others, and some corneas are more challenging to mold. Some cases will need more expensive materials. Once we evaluate the patient we can then present the appropriate fees for that case.
- Chicken! Simply put, that applies to the patient who is afraid to touch their eyes. This is RARELY a barrier. At times some children are not ready to touch their eyes OR be responsible enough to insert the molds on a nightly basis. This can be alleviated in most cases with training and time.
Just as in LASIK, the intended corneal topography change in a nearsighted individual is to make the central part of the cornea flatter, which causes a ring of adjacent steepening (the red ring). This is important to understand. When light enters the eye of a nearsighted patient, it focuses in front of the retina. This is caused by one of two factors, the eye is too long (typically) or has too strong of a corneal curvature.
In order to see well the light entering the eye needs to be made more divergent to land on the retina (PUSHES THE FOCUS POINT BACKWARD). This is accomplished by making the corneal curvature flatter or less sharply curved. Flattening the central curvature results in an adjacent area of steepening. That is the ‘red ring’ you see on this cornea. The ‘magic’ of the red ring is that the steeper area cause light to focus in front of the retina (PULLS THE FOCUS POINT FORWARD).
The result of this “pushing and pulling” of the light in the eye creates focused light in the whole back of the eye (“pan-retinal focus”). Glasses cause light to be in focus solely in the central retina and behind the retina in the periphery (which encourages axial elongation, or eye growth). This is why and how the ‘child who gets more nearsighted every year’ significantly slows to STOPS PROGRESSING! This is the most powerful tool we have to stabilize the younger eye.
There are other tools and procedures to slow the rate of progression of nearsightedness in the younger eye. Some are:
The CANDY Study (Controlling Astigmatism and Nearsightedness in Developing Youth) is a study performed by Dr. Peter Wilcox and Dr. David Bartels which showed that kids who participated in overnight corneal reshaping had a near total cessation in the progression of the nearsightedness which they were experiencing prior to molding. The graph below shows how the kids were getting worse before molding by an average of 0.50 diopters per year (blue line) and then only progressed at a near-zero rate of 0.05 diopters per year after starting corneal molding (orange line). You can read the whole study here (CANDY Study, 2008).
Hyperopic Corneal Molding
Whereas very few doctors offer Corneal Molding (Orthokeratology) to their nearsighted patients, the molding of eyes for the correction of farsightedness reflects a fraction of those providers. The molding of a nearsighted eye requires a flattening to occur. The molding of a farsighted eye requires the exact opposite, the cornea must be made steeper after the lens is removed. This is much more difficult to accomplish.
Who is a candidate?
- Farsighted patients of all ages.
- Presbyopic patients in the need of reading glasses.
What are the limitations?
- Though nearsighted patients with prescriptions as high as -10.00DS have been successfully molded, the ability to steepen a cornea is more difficult and the bar is much lower. The baseline topography and many other conditions are considered when forecasting success. It is safe to say that limits below +4.00 can be considered on a case-by-case basis.
Who is the typical patient?
Believe it or not, the patients who most utilize hyperopic molding are those with no distance prescription or are low hyperopes (farsighted) and over 40 years of age who need reading glasses and find them inconvenient. The hyperopic molded cornea is a center-near bifocal. These lens designs are routinely fit in soft and gas perm materials for all-day use. The molded result gives the patient daytime freedom from glasses and reading glasses. In some cases for those with higher distance prescriptions and stronger bifocal powers there can be a forecasted expectation that the patient may need a slight reading glass correction. That infrequently realized compromise is happily accepted by that population of patients who are otherwise crippled without their thick bifocal glasses.