Orthokeratology

WHAT IS ORTHOKERATOLOGY?


First and foremost we want to make clear that we do NOT adjust night lenses. When you got problems with standard lenses we think superlenses or lasik are a better solution than night lenses. Click on the links to know more.

  The advantages and disadvantages of night lenses:
  Ortokeratologie is a technique that corrects myopia, via working on the cornea  ( = frontside of the eye). Since 1993 they use special, high oxygen permeability hard lenses, that change the form of the cornea at night. This change occur because of the surface cells  (“epithelial cells”), those cells change while you wear the lens. First they thought that those cells were pushed to the sides  (“redistribution”). Recent study shows that the epithelial cells are pushed flat. That way the cornea becomes flatter and the present myopia is reduced. This effect stays the whole day, so you see good without lenses the whole day! After a while the lens only has to be worn a few times a week !
  These lenses are only made from high oxygen permeable material (such as  Boston XO) . This material is one of the few materials, that is admitted by the American Food and drug administration for the fabricating of day and night lenses.
  HOW DOES ORTHOKERATOLOGY WORKS?

If you previously wore lenses, you have to let the lenses out for 1 or 2 weeks. With a special apparatus (“topograaf”) the size of the cornea is measured. On that size and based on de refraction-aberration, the superlenses are made. Superlenses have a "reverse geometry”: central pressure / in the middle periphery a little bit abnegate/ on the side connecting.   Thanks to the high precision of the topograaf is the first lens in 80% of the cases the right lens. The adaptation is fast, safe and predictable. Average, people are capable to function without lenses during the day after several nights wearing the lenses: 60 % of the myopia is gone after 1 night, after 3 to 4 nights the myopia is gone 100% in the morning, but returns in the evening. After 1 month you won't have that problem anymore.  In that period you can also wear the nightlenses during the day. The lens also gives good view during the day! After a month you have a condition that is at least 18hours stable. That lenses aren't necessary during the day people experience as an advantagel !  But they forget to say that it is realy bound to a nightly routine! If you don't have that routine the myopia will come back!   WHO IS ELIGIBLE FOR ORTHOKERATOLOGY?

Patiënts with a myopia of  –0.75 to –4.5 D and a cylinder with a maximum value of –1.50 on 180° to maximum –0.75 on 90°.  Mainly patiënts with comfort complaints with their present lenses, think of night lenses. Also people, that can't tolerate lenses or that can't wear lenses because of their profession (dust!). 

    WHAT ARE THE ADVANTAGES COMPARED TO LASER?

The main advantages are:

  ·         The method is safe with remarkably less complications. Intermittent nightly irritation, inflammationd and little cornea-wounds (“erosies”) are one of the possiblities, that (with bad care) can lead to cornea-scars.

  ·         The procedure is totally reversible: after a few weeks the cornea is back to normal. In the beginning it only takes a few days before the myopia is back. A light myopia (to -3 ) is an advantages on the age of 45, to read without glasses. You don't lose this advantages if you choose for night lenses.

  ·         Very fast habituation, because the eye doesn't move many at night

  ·        Possible under 18 years

    WHAT ARE THE DISADVANTAGES COMPARED TO LASER?

·         The night lenses work via distortion of the cornea. Whether this will be tolerated on long term isn't known. Now they know patients with a pigment line in the cornea (“Stahli-lines”), what points to permanent differences!  You have to go regular to your specialist to see if everything is still ok!

  ·         Every damage or pollution of the lens make that the effect of the lens changes. Unfortunately the lens get dirty real fast, because the lens doesn't move much during the night. It takes an effort from the lenswearer to maintaine the lens good (intenser than a normal hard lens !). Therefore the lens is replaced after maximum 1 year.

  ·         Ortokeratology is on term expensiver and labor-intensiver than lasertreatment: It demands different consultations, definitely in the beginperiod, to see if the lens gives the desirable results without problems.  It suffices that (for example) there are air bubbles between the cornea and the lens at night, to identify abnormalities! The lenses have to be replaced regular (at least yearly).  Morefor there is a variability in the effect with patients: the one reacts very well / the other had less effects than expected !  The effect isn't permanent, when you stop wearing lenses.  Sometimes the effect can fluctuate during the day (definitely the first month!): in the morning better view / in the evening a little bit less, with a light myopia as result.  You can wear your night lens during the day to see better! 

  ·         The optical zone for a myopia of –3 is only 4 mm !!  An optical zone of a laser (6.5 mm) is clearly better for nightvision !  Nightlenses are best for myopia between –1 and  –2.5,it is limited. Besides, those patients don't always have to wear their glasses, only for TV or driving the car,....

  ·         That the effect of the lenses disapears is also a disadvantages: Their are periods of fluctuating vision at the evening or when you didn't wear the lenses for 1 or 2 nights. You never get rid of your lenses !

  ·         The maintenance of the lenses is crucial. Otherwise you will experience less visibility for a couple of months, because the deformation is different than with a clean lens. So you understand the famous “ 6 months –syndrom” : less good view after 6 months, because your lenses are dirty and don't have the desired effect !!

  ·         Be careful that you don't swith the lenses from side. The effect will be different than calculated. Therefore many lensspecialists give the righter lens an other color than the left lens.

    CONCLUSION

Laser  is better:  quicker result / the result is final / less consultations necessary / bigger optical zone / bigger range: from +3 to –10  . Below 18 years you can talk of ortokeratologie !