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Why should we remove contact lenses for several days before the consultation for refractive surgery?

Contact lenses are in contact with the cornea, which is operated in tissue LASIK or PKR. Regardless of the correction they provide, these lenses have a geometry (diameter, thickness), and a special "stiffness" (eg: soft lens, semi-rigid lens, hard lens, etc.).

The permanent contact with the anterior face of the cornea (epithelial face), the friction induced by the blinking induce with time a modification of the geometry of the cornea; We talk about the distortion induced by contact lenses (' Corneal warpage ' in English). The term "contact lens-induced deformation" therefore refers to the transient changes in the corneal topography induced by contact lenses. These modifications are more frequent after the prolonged use of rigid gas-permeable contact lenses. The topography corneal allows to highlight these deformations, which affect the anterior face of the cornea (interest of the topography Placido). The majority of the lens-induced deformations concern the corneal epithelium, which is "remodeled" according to the mechanical stresses induced by the lens. For example, the epithelium tends to be thinner in relation to areas with strong support.

It interesting to note that theOrthokeratology, which consists in making a (transient) correction of myopia by adapting rigid lenses that are worn only at night during sleep, is based on the induction of a "warping" characterized by a central flattening (allowing to correct the Low myopia and some of the average myopia). When the port of the lenses is interrupted, the corrective effect disappears in 36 to 48h, but the realization of a more remote corneal topography often reveals the presence of residual corneal deformation.

 

Topographical aspects of the corneal warpage (corneal warpage):

Topographic anomalies may consist of a astigmatism irregular Central, the reduction of the negative corneal Asphericity (reduction of the prolate Asphericity), an appearance in 'asymmetric bow' ('bow - tie asymmetry') or localized areas of camber. Rigid lenses usually produce a higher kurtosis and a relative lower camber due to the flattening of the underlying cornea to lens which is often "hung" or "lifted" in superior by the upper eyelid.

Corneal topography in axial (upper) and tangential (bottom) mode in a patient with rigid lenses. The lenses were removed the day before the consultation. Note the aspect of asymmetric butterfly knot in axial mode. In tangential mode, the central flattening is quite evocative.

It is important to distinguish between transient abnormalities induced by lenses and permanent anomalies likely to alter the topography of the cornea. Here are the reasons:

-a false appearance of beginner Keratoconus can be induced by the lenses (asymmetry)

-deformation induced by the lenses can hide, or at least blur one aspect of Keratoconus beginner (risk of ectasia if LASIK)

-a deformation of the cornea can alter the optical correction: in general, the rigid lenses induce central flattening, and this flattening results in a reduction of the optical power of the cornea. Native myopia is partially reduced, and this causes a risk of slot correction if one takes measurements while the corneal deformation remains.

Note that this property of 'deformability' of the front of the cornea is put to good use by the technique of Orthokeratology, adapting rigid lenses whose geometry is designed to induce a "crushing" of the central part of the anterior cornea.  This technique is little practiced in France, and was mainly developed by Anglo-Saxon optometrists. These lenses are worn overnight, and withdrawn wake up: central corneal flattening a few hours during which a myopia understood between - 1 and-3.5O D can be temporarily corrected.

Type of lens and corneal deformation duration:

Wang et al. (2002) prospectively studied the eyes of 165 consecutive patients with lenses evaluated for refractive surgery. A significant corneal deformation induced by contact lenses was detected by corneal topography in 20 eyes of 11 patients (12%). In patients with contact lens-induced deformation, the mean anterior port duration of lentils was 21.2 years (extremes: 10-30 years). The average recovery time before refraction stabilization, kératométriques values, and topographic profile was 7.8 ± 6.7 weeks. Recovery rates were different depending on the type of lens: extended-port flexible lenses 11.6 ± 8.5 weeks, soft-o-rings 5.5 ± 4.9 weeks, daily port soft lenses 2.5 ± 2.1 weeks and rigid lenses permeable to Gas 8.8 ± 6.8 weeks. This study showed the need for repeated refractions, kératométries, and documented stable contact topographies before planning refractive surgery in patients with suspicion of corneal deformation.

IN PRACTICE:

When a patient consults for refractive surgery (e.g., myopia surgery), the topographic assessment should ideally be performed at least a few days to 1 week after the port of soft lenses is stopped, although in most case modifications related to the wearing of soft lenses are very minor and do not interfere very significantly with measured visual correction and corneal topography.

After stopping the wearing of rigid lenses, it is recommended to wait longer, i.e. at least 3 weeks to a month before proceeding with the evaluation. If corneal anomalies are detected by the topography, a monthly assessment should be carried out until the topographic profile is stabilised. At least two topographies with the same profile are recommended before planning a refractive surgery: this is because it is necessary to ensure a return to the "stable" state of the cornea to confirm the operability (topographic normality) and to ensure To make a suitable correction.

Reference: Wang X, what JP, Bowman RW, HD Cavanagh. Time to resolution of contact lens-induced corneal warpage prior to refractive surgery. OALCF J. 2002; 28 (4): 169-71.

15 responses to "why should contact lenses be removed several days before consultation for refractive surgery?"

  1. raziel013 says:

    Hello

    I know that the article is several years old but I am facing this problem of corneal deformation due to wear lenses.

    I want to have the surgery.

    I stop wearing the lens for 5 weeks and there has been no improvement to the level of the topography of the cornea. I see that depending on the type of lenses, it may take more than 5 weeks but is it normal to have no improvement in the first few weeks?

  2. Dr. Damien Gatinel says:

    All corneal deformities are not related to the port of contact lenses. Soft lenses induce no (or little) deformation. On the other hand, with the rigid lenses, several weeks are sometimes necessary for induced deformation (corneal warpage in English) subsides. If this is not the case, the deformation is certainly caused by other mechanical cause, such as eye rubbing, and/or prolonged night support on hand, the elbow, the pillow, etc.

  3. Dr. Damien Gatinel says:

    It is possible that the deformation of your corneas is not (only) related to wear the lenses. In some patients, the practice of eye rubbing repeated with the fingers (eyes itch, Sting, etc.) can lead to induce a permanent deformation of the horny (s). I also often observed that sleep position, especially of the head towards the pillow could also lead to a deformation of the cornea, on the side of the support (patients who sleep on their stomachs have necessarily front-end support against the pillow head and tilt it to one side or the other, what generally causes a contact of the orbit with the pillow , or the forearm, or both, etc. This night, comparable compression can be one that cause the day rigid lenses, is logically able to deform the horny (s). I advise you to investigate on this side, and be sure that you do not rub the eyes of chronic, daily way, even unconsciously.

  4. SMAOUI NAMS says:

    Hello
    I have been wearing color lenses for several years (10aans), I have to have cataract surgery in a few months. I would have wanted to know if eventually I could continue to wear colored lenses.
    Thank you in advance for your reply.
    Emna

  5. Dr. Damien Gatinel says:

    A priori it is possible to postpone color lenses after cataract surgery.

  6. Tillette says:

    Hello

    I met my DPO. I wear contacts for 20 years. I took out them just before my RV at the OPH. It has found me a beginner cataract. The lenses were able to distort the eye exam?
    I went to the RV with my glasses but about 1 hour before I wore my lenses.

    My DPO always told me to remove my lenses at least 5 hours before I met him.

    Thanks to those who want to find out if the lenses were able to distort the eye exam or not.

  7. Dr. Damien Gatinel says:

    The presence of lenses does not interfere with the diagnosis of cataracts, which is based on direct examination of the eye to the biomicroscope (presence of a clouding of the lens of the eye). The symptoms of cataract are the sensation of a veil, a blur of glare, a need of light increased to read, etc.

  8. Coralie says:

    Hello

    I consulted my ophthalmologist for an operation of my myopia (-2.5).
    Since 1 year I can no longer support lenses (irritations and dry eyes) unless they are very moisturizing (like total daylies).
    Today the ophthalmo has evaluated my cornea at 480microns...
    Do you think my cornea is too thin for a laser operation? The fact that I wore my flexible lenses daylies total 1 week before the check test was it possible to reduce the thickness of my cornea? I specify that my ophthalmo told me that I still have "residues" (I'm no longer sure that he used exactly that term) of lentils in the eye and that we had to do more thorough examinations before I could say if I am operable..

    Thank you very much in advance for your answers!

  9. Dr. Damien Gatinel says:

    In general, the influence of soft contact lenses on the measurement of corneal thickness is low. Nevertheless, the possibility of carrying out an intervention of PKR (surface laser) exists, for this degree of myopia and for such a corneal thickness.

  10. Vincent says:

    Hello

    I'm going to undergo a refractive surgery for LASIK myopia in a few weeks, on a Monday at 12:30.
    I have been wearing daily soft lenses for several years now and my surgeon has told me to stop wearing them 48h before the operation.
    Only problem I fight a sporting competition on Saturday before the operation that requires the wearing of my lenses and so I could only remove from about 5pm.
    So my question is the following, the delay without wearing lenses between Saturday 5pm and Monday 12h is it enough and does it not risk to pose a problem for the operation?

    Thanks in advance for your reply,

  11. Dr. Damien Gatinel says:

    A priori this is enough time.

  12. Them says:

    Hello
    I'm getting Opere of myopia in 4 days and I wore my lenses 3 days this week.
    Is it serious?

  13. John LAURIE says:

    Hello

    I have been wearing soft lenses for about twenty years and I have embarked to pass the examinations of topography for a possible operation of nearsightedness to LASIK.
    I am myopic and asthygmate-8 to eye g and-5.75 to the right eye.
    I would really like to know how long before the survey of topography I have to remove my lenses because without lenses I am perdue.ET my glasses more at all at my sight.
    My exams are Monday, October 9, 2017. My concern is great because I would not want to distort the results.
    THANK YOU VERY MUCH FOR YOUR REPLY
    LAURIE

    Thanks in advance for your answer

  14. Dr. Damien Gatinel says:

    If you wear soft lenses, the delay for removal is about 48 hours. If your lenses are rigid, you should have a minimum of about 3 weeks.

  15. Dr. Damien Gatinel says:

    A priori this is not a real problem for the intervention.

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