Stability after laser in situ keratomileusis in moderately and extremely myopic eyes

The aim of this study was to compare regressive eyes with non-regressive eyes after laser in situ keratomileusis (LASIK) for myopia with regard to the time course of biomechanical changes of the cornea and to evaluate the possible roles of these changes in refractive regression following surgery. 15 eyes of 9 patients with refractive regression and 15 eyes of 11 patients with no refractive regression after LASIK for myopia were enrolled in this study. The time courses of central corneal thickness (CCT) and anterior/posterior corneal curvature radiuses (CCR) were measured with Orbscan slit scanning before and 1 week, 1 month and 3 months after LASIK for myopia. The regressive and non-regressive eyes had similar time courses of CCT before and after LASIK, whereas the 2 groups differed in the time courses of corneal shifting movements. In the regression group, the posterior CCR after LASIK was relatively stable (all p > 0.05). By contrast, in the non-regression group, the postoperative posterior CCR at week 1 had a significantly steeper curvature than that at month 3 (p = 0.000). The anterior CCR in the regression group at week 1 had a significantly flatter curvature than that at month 3 (p = 0.002) postoperatively. In contrast, there was no significant change of anterior CCR postoperatively (all p > 0.05) in the non-regression group. Taken together, these data suggest that refractive regression after LASIK might be mainly induced by corneal protrusion rather than central corneal thickening.

Section: Discussionmentioning

confidence: 98%

Differences between Regressive Eyes and Non-Regressive Eyes after LASIK for Myopia in the Time Course of Corneal Changes Assessed with the Orbscan

Pan¹,

Gu²,

Wang³

et al. 2004

“…Although the long-term outcomes of our study seem to be less favorable than other studies, the fact that there were 85.07% of eyes with myopia ≥–10.0 D in our study perhaps influenced the statistical results. It is known that with an increased amount of attempted myopic correction, it takes longer for refraction to stabilize than after smaller corrections [35]. …”

Section: Discussionmentioning

confidence: 99%

Outcomes of Epi-LASIK for the Correction of High Myopia and Myopic Astigmatism after More than 1 Year

Gan¹,

Zhou²,

Dai³

et al. 2008

Purpose: To present the clinical results of epi-LASIK in a high myopia and myopic astigmatic population followed for more than 1 year. Methods: This retrospective study comprised 67 eyes of 52 patients who underwent epi-LASIK for the correction of high myopia and myopic astigmatism. Epi-LASIK was performed with an automatically rotational epikeratome (KM-5000D, Wuxi Kangming Medical Device Corp., Wuxi, China) and the MEL80 (Carl Zeiss Meditec, Jena, Germany) excimer laser. The postoperative symptom, epithelial flap, vision, refraction and haze formation were investigated. The astigmatic change was calculated by the Alpins vector analysis method. Results: The follow-up period was 13.27 months. Mean preoperative spherical equivalent (SE) refraction and cylinder were –13.39 diopters (D) and –2.02 D. An integrated epithelial sheet with a diameter of about 8–9 mm was made in 65 (97.01%) eyes leaving a superior hinge of approximately 2–4 mm. The mean epithelial healing time was 5.55 days. More than 1 year after the treatment, no eye lost more than 1 line of best spectacle-corrected visual acuity. The mean SE and cylinder were –2.25 and –0.79 D. The mean astigmatism correction index was 1.06. The index of success of 0.51 reflected a 49% success in achieving cylinder correction. The change induced by the laser ablation at the intended axis of cylinder reduction was 93%. At the same interval, 7.46% of eyes had trace haze and others were clear. Haze did not affect the visual acuity in any eye. Conclusions: Epi-LASIK appeared to be effective and safe in the treatment of high myopia and myopic astigmatism with the advantages of having lower postoperative pain and satisfactory refractive and visual outcome postoperatively.

“…The study performed by Chayet et al [1], without the control of nonregressive eyes, indicated a progressive increase in CCT in the eyes with refractive regression after LASIK. But Magallanes et al [11] reported a significant myopic shift with only a slight increase in CCT, but a slight myopic shift with a significant increase in CCT after LASIK. Pan et al [12] compared regressive eyes with nonregressive eyes after LASIK and indicated that refractive regression after LASIK might be mainly induced by corneal protrusion rather than by central corneal thickening.…”

Section: Discussionmentioning

confidence: 99%

Regression-Related Factors before and after Laser in situ Keratomileusis

Qi¹,

Hao²,

Xia³

et al. 2006

The aim of this study was to evaluate the refractive regression-related factors before and after laser in situ keratomileusis (LASIK) for myopia and give a reasonable way to prevent it. The consecutive patients who underwent LASIK from January to June 2004 were reviewed retrospectively. Thirteen eyes from 8 patients with myopic regression and 60 eyes from 42 patients with no myopic regression within 12 months of follow-up were enrolled. We compared the pre- and postoperative data which were associated with regression in the two groups. The mean preoperative intraocular pressure (IOP) was significantly higher in the regression group than in the nonregression group (p = 0.03). During the period of 12 months, the two groups differed in corneal bowing. In the regression group, both posterior and anterior corneal surfaces were significantly bowing (all p < 0.05). In contrast, in the nonregression group, both posterior and anterior surfaces were relatively stable (all p > 0.05). The higher preoperative IOP and the progressive postoperative biomechanical bowing in the posterior and anterior surfaces of the cornea are two factors related to myopic regression in this study. Lowering the IOP preoperatively and postoperatively may be an effective way to prevent the myopic regression after LASIK.