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EYE CARE INFO & UPDATES
This follows from my last eye blog, Ortho-K: How Does It Work?
How long does Ortho-K take to correct vision?
The length of time it takes for Ortho-K overnight lenses to fully correct your vision will depend on your pre-treatment prescription and your individual eye shape. Other factors include quality and length of sleep each night (7-8 hours is ideal), consistency in wearing the lenses regularly, rigidity of the eye surface layers, the cornea, that can vary from person to person, lens design parameters, pupil size, presence of and amount of astigmatism to be corrected and the curvature of the eye surface.
In my practice, all our Ortho-K patients have enjoyed significant improvement in their vision even after just one night of lens wear. Typically a patient with a medium level of short-sightedness, say -3.00 dioptres of myopia, will have over half of this prescription (around -2.00D) corrected already at their first review, in the morning following their first overnight wear of the lenses. By the end of week 1, he or she will have about 85% (around -2.50D) of their prescription corrected, and this further improves in the 2nd week to achieve 6/6 or 20/20 vision.
Some patients experience faster vision correction progress, and some slower — this is normal as each individual's eyes are different. Some optometrists or websites may claim to be able to achieve 20/20 vision after one night of Ortho-K — while this may be possible in some cases with a simple prescription, I prefer my patients to have a realistic expectation of their treatment progress and outcome.
As part of our Ortho-K Package for first time wearers we can provide, where needed, a spare pair of glasses made with a mild correction to help you see clearly during your first few weeks of Ortho-K treatment. This pair of glasses is also helpful for those who wish to wear their Ortho-K lenses every 2nd or 3rd night, instead of every night. As the treatment effect begins to wear off the glasses help to support their vision until they resume Ortho-K lens wear. Ortho-K vision correction is flexible, not everyone will need to wear their lenses nightly, depending on their personal vision needs and the holding time of their Ortho-K treatment.
Individuals with astigmatism (uneven eye surface curvatures) tend to take a little longer to reach optimum vision. This is because the corneal reshaping involved in an eye with astigmatism is more complex. Astigmatism is corrected using customised dual-axis Ortho-K lenses. Some patients have astigmatism in one eye and not in the other, and these patients often will have faster vision correction in the eye without astigmatism, and with about 1 week difference between the two eyes in reaching the optimum vision outcome.
Higher levels of short-sightedness (high myopia of over -6.00D) will also take longer for good visual outcome to occur, as greater amounts of eye surface flattening is required. Typically around 3 weeks for full or close-to-full correction is my advice to patients with high myopia considering Ortho-K lenses. During this initial period when treatment effect is gradually building we supply temporary soft contact lenses in steps of decreasing power to support the individual's daytime vision. With higher prescriptions it is normal for an individual to experience some ghosting and halos around lights, particular in dim conditions and at night. This usually improves with time as the Ortho-K treatment effect increases across a wider area on the eye surface.
With very high prescriptions (eg. -8.00D short-sighted) it may not be possible to fully correct vision to 20/20 due to lens and biological limitations, in which case the individual may be left with a residual amount of short-sightedness (eg. -1.00D after a correction of -7.00D with Ortho-K for a -8.00D individual). This is termed 'partial correction'. Many patients with very high prescriptions are happy with a partial correction as it already significantly reduces their dependency on glasses, and if they do need to see clearer they can wear a light prescription pair of glasses during the daytime, rather than their usual thick and heavy glasses.
In summary, these are the typical timeframes for Ortho-K lenses to effectively correct vision in most individuals:
Low level myopia (less than -2.00D) — 3-4 days.
Medium level myopia (-2.00 to -4.00D) — 1 week.
Moderate level myopia (-4.00 to -6.00D) — 1-2 weeks.
High level myopia (more than -6.00D) — 2-3 weeks.
EYECARE CONCEPTS — ORTHO K PRACTITIONER — MELBOURNE
Philip Cheng - B.Optom (Melb) Ocular Therapeutics (GCOT). Optometrist at Eyecare Concepts Kew East, Melbourne. An experienced eye care & contact lens practitioner with expertise in myopia control & orthokeratology.