Contact Lenses: Ortho-K (Corneal Reshaping)

Happy Monday, y’all!

In today’s post, I’m taking a break from the world of neuro to answer a reader question.

JM writes: Do they still do corneal molding?  I did that for a while and loved it! I wore contact lenses at night, took them off in the morning, and could see without anything!  After a while, I didn’t even have to wear them for several nights at a time and could still see!  Freedom!!

First off, thank you so much for your question, JM!  And, believe it or not, yes we  still use corneal reshaping (or ortho-keratology) in practice! Keep reading to learn more!

Ortho-Keratology (Ortho-K)

What is Ortho-K?

As JM described in her question, Ortho-K is a process by which the cornea is molded by wearing specialty hard contact lenses over night to correct (myopic/near-sighted) refractive error.

How It Works

This process that was first introduced in the 1960s uses a gas permeable lens design that sits directly on the cornea, rather than slightly vaulting over it, to create a flattening effect.  This flattening decreases the radius of curvature of the cornea (steepness), secondary to temporary epithelial redistribution, therein decreasing its convergent power.  As myopic or near-sighted eyes have a focal point in front of the retina, this change in convergence repositions the focal point, optimally on the retina.

With that in mind, it only makes sense that different eyes will require different amounts of flattening to correct the prescription, with higher prescriptions necessitating more flattening, and lower prescriptions needing less.

This flattening is focused over a (generally) four millimeter treatment zone.

Process

Once the decision to pursue Ortho-K has been made, the process of fitting and prescribing generally goes something like this:

  1. Complete eye exam, including refraction, dilation and thorough front surface/corneal evaluation: Ensures the health of the eye and determine the current refractive needs
  2. Corneal measuring, using a keratometer: Determines the parameters of the lens for fitting
  3. Lens fitting, or actually putting lenses on the eyes: Making mild adjustments until the appropriate fit and vision are achieved
  4. Insertion/removal training: Learning how to properly use the lenses themselves
  5. Lens dispensing: Sending the lenses home
  6. First follow-up: Generally a morning appointment after the first night of wear, with the lenses still in, to verify the fit of the lenses after wear
  7. Additional follow-ups: Often spaced at one, two, four, and eight weeks to continue monitoring stability of fit

Pros

As JM mentioned, Ortho-K can be incredibly freeing, allowing patients to go without glasses or contacts during the day (and sometimes even a few nights).  This then provides an attractive, reversible alternative to LASIK.

Cons

While Ortho-K can be an awesome option for refractive error correction, it isn’t for everyone.  Some common complaints are:

  • Lens intolerance: Ortho-K requires sleeping in a hard contact lens. For those of you who have never worn them, hard lenses are called hard lenses for a reason – they’re modestly hard pieces of plastic!  While most people adapt to the lenses well, some people cannot tolerate even overnight wear of the lenses.
  • Glare/halos/distortions: This process is literally moving some of the cells on the front surface of your eye to temporarily change the power, which can cause distortions in vision – especially when driving at night, in the form of glare and halos.  It’s the worst in patients with large pupils that extend past the treatment zone, putting those distortions directly in your line of sight.
  • Temporary correction:  While JM was one of those with a successful enough Ortho-K run to be able to go several days without retreatment, this is not the case for everyone.  Some people report visual changes before the end of the day, requiring additional lenses for clear vision in the evening.
  • Risk for infection: While this risk is relatively low, it’s worth mentioning, after all, Ortho-K requires sleeping in contacts.. which is normally highly discouraged by providers.
  • Prescription parameters:  Due to the corneal flattening nature of Ortho-K, is primarily indicated for people who are near-sighted, or myopic.  Additionally, it works best on moderate to low prescriptions, with mild amounts of astigmatism.

Additional Indications

In relatively recent years, Ortho-K has been investigated as a method of controlling myopia progression in children and teens, secondary to its creation of peripheral myopic blur.  This myopic blur serves to inhibit axial elongation (or prevents the eye from getting longer), therefore decreasing myopic progression.  While results vary by case, studies have proven that Ortho-K may reduce progression by, on average, 45%.  As such, Ortho-K is an attractive option for young, near-sighted individuals, as it provides unobtrusive day-time refractive error correction while concurrently reducing myopic progression.

Personal Experience

My first personal experience with Ortho-K was during the summer of my first year of optometry school, when I was lured by the financial gains and visual promises of a corneal reshaping study. The process went much like how I described above, with the exception of some additional study related measurements and paperwork.  All seemed to be going well until somewhere around a week or so into the study – I had even been able to go without wearing any lenses for the first time in like 13 years.  It felt so freeing!

Until I went out of the sun.

Everything was blurry. Everything had halos.  I got dizzy and nauseous just looking around.

But I was determined to succeed and convinced it would pass, if only I wore the lenses more.

(Mind you, this was over July 4th, and I was on vacation.)

I tried.  And tried.  And tried.  No matter how many hours I wore the lenses (which became increasingly difficult as the irritation of wearing the lenses increased), nothing got better.  I was miserable.

Finally, I texted my contact in the study and informed her that I could take it no longer.  Whether she liked it or not, I was done.  I threw on my brother’s glasses (which happened to be just the prescription that I needed during the transition), and never looked back.

A few weeks later when I returned to school to turn in my lenses, I discussed my results with the study coordinator.  Our best guess theory was that a combination of my relatively large pupil size and moderately high prescription (I was at the upper bounds of the study limits) created the distortions that plagued me during the study, and while we were curious of the effects of a larger treatment zone on my visual outcome, I was too over it to continue.

Takeaways

Considering my personal experience, it would probably be reasonable to wonder if I believe in prescribing Ortho-K lenses at all.

Admittedly, it did take me a while to come to terms with the benefits of the lenses, but now, I am happy to prescribe corneal reshaping therapy.  It definitely has its place in current optometric practice, and over time, I have come to accept that my experience was more of an exception, rather than the rule.

With this in mind though, I am more cautious with Ortho-K prescribing, typically preferring it for younger patients with fewer visual demands and a lower prescription.


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