LASIK for high hyperopia with the SCHWIND AMARIS

Laurent Gauthier, MD, Espace Helios, Saint Jean de Luz, France

The treatment of high hyperopia in corneal refractive surgery has always been a challenge. The results of different published series are highly controversial.

as these results are directly dependent on the technology used in the surgery. The SCHWIND AMARIS laser family can treat high hyperopia efficaciously under certain conditions; among others, thanks to its specific ablation profile wherein, unlike other popular laser platforms, the size of the transition zone varies according to the magnitude of the hyperopia to be treated. For instance, for a treatment of +1.50D with an optical zone of 6.70 mm with the SCHWIND AMARIS, the total treatment zone will be 7.81 mm, whereas, for a treatment of +6.00D with the same optical zone of 6.70 mm the total treatment zone will be as large as 9.20 mm. The higher the amount of ablation in the periphery, the more important it is to optimize the optical quality. Only a fast laser with a very high frequency can achieve such high ablations without increasing the treatment time, which is a source of stromal dehydration, loss of fixation and patient discomfort. It can be seen that minimum post-op corneal spherical aberrations (Z[4,0]) are induced, even for high refractive corrections, demonstrating the optical quality of the achieved ablations (figure 1).

The size of the effective optical zone is even more important in the context of hyperopic refractive corrections than for myopic refractive corrections of the same magnitude (figure 2). In our series of 186 eyes treated for a spherical equivalent with an average of +5.35D (range +4.00 to +7.50D), with astigmatism up to 4.50D (average 1.73D), following outcomes were obtained 4 months post-operatively: 62 % of eyes were within SEQ of ±0.50D, 93% of eyes within ±1.00D. The very good CDVA is preserved postoperatively.

The probable reason for this is the systematic use of an optical zone of at least 6.70 mm and a total treatment zone of 9.20 mm in most treatments. For such large treatment zones, a flap size of at least 10 mm is recommended. To achieve this, we use a microkeratome with a special ring for high hyperopia. Nasal hinge is routinely performed which allows to expose a larger corneal surface compared to the superior hinge. Furthermore, a nasal hinge is also less disturbed by the rolling movements of the eye, more pronounced in hyperopic patients during surgery.

  • Taking into account the often significant offset seen in high hyperopic patients, my technique is to shift the ablation map with the centration axis to minimize the induction of unwanted aberrations (figure 4).
  • In a young farsighted patient it is common to see a big difference between the optical correction worn and the cycloplegic refraction. Wearing a higher optical correction for a few months may reduce the accommodative spasm and will allow a better correction of the true latent hyperopia.
  • Small corneal limbal diameters may hamper the outcomes in high hyperopic treatments, since the cut may cause bleeding especially in contact lens wearers. These small corneal diameters are found most often in corneas with high hyperopia and steep keratometries. In those patients, the use of large treatment zones may be a contraindication.
  • A discreet initial overcorrection is systematic both for hyperopia and for astigmatism. The patient should be informed about the visual discomfort in far vision during the early days of postoperative recovery.
Offset Factor used to shift the ablation map by Laurent Gauthier in english

Figure 4: My offset technique

The bad reputation of high hyperopic corrections is linked to the deep ablations being performed in small optical zones and with a low optical quality, which may result in a high amount of aberrations. The consideration of centration axis and use of large treatment zones are the most important requirements for a successful outcome. The correction of high hyperopia is possible, however, following much stricter protocols compared to the myopic corrections. An imperfect realization of the intended hyperopic correction may have far greater consequences. But following these advices, and using modern technologies such as SCHWIND AMARIS, hyperopic corrections can be accomplished with greater level of success than ever before in LASIK up to +7.00D, whereas more concerns are associated with hyperopic corrections in PRK beyond +4.00D.

Dr. Laurent Gauthier, Espace Helios, France
Espace Helios
Saint Jean de Luz, France
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