Laser assisted in situ keratomileusis (LASIK) has become one of the most popular options for the correction of low to moderate myopia worldwide. However, vitreoretinal complications including endophthalmitis, retinal tear and detachment, retinal haemorrhage, and choroidal neovascular membrane have been reported.
Chan and Lawrence have reported three eyes of three myopic patients that developed a macular hole in one eye after bilateral LASIK or photorefractive keratectomy (PRK). Ruiz-Moreno et al recently reported a case of a macular hole in a myopic eye after LASIK. We previously reported in a letter to the editor 10 eyes (10 patients) with full thickness macular hole development after bilateral LASIK for the correction of ametropia.
DISCUSSION
Our findings support previous studies that showed the characteristics and demographics of myopic macular holes to be different from those of idiopathic macular holes. Myopic macular holes tend to develop in young subjects and may be associated with a retinal detachment surrounding the macular hole.
In the present series, posterior vitreous detachment was not present before and was documented after LASIK on 42.8% of eyes. Luna et al have used kinetic ultrasonography to demonstrate vitreoretinal alterations after LASIK, including partial or total PVD in 24% (12 eyes) in high myopes. Their findings are consistent with similar results in almost half of myopic eyes with macular hole after LASIK in our series.
Macular hole surgery can achieve substantial VA improvement for myopic eyes, but the results do not seem to be as favourable as those reported for typical idiopathic macular holes in recent series. In our series, only four (28.5%) eyes out of 14 had a VA outcome of 20/40. Case 12 was our only case with loss of VA after vitrectomy. However, silicone oil removal and cataract extraction are still pending, and could potentially improve final VA. Our results should be interpreted with caution, since multiple surgeons with different surgical techniques and training participated in this study.
The pathogenesis of macular hole remains controversial. Certainly, vitreofoveal traction is felt to be the predominant force together with pre-existing degenerative changes in the fovea. Chan and Lawrence have stated that LASIK surgery has certain features that may induce postoperative vitreoretinal interface changes. For instance, the acute intraocular pressure rise associated with the mechanical stretch of the vitreous base induced by the suction ring as well as the shock waves generated by the excimer laser may lead to vitreoretinal traction. Retinal breaks and detachment have also been reported to occur after laser in situ keratomileusis.
Our findings are not generalisable to all myopic eyes that undergo LASIK. However, myopia is a risk factor for macular hole formation. It is possible that vitreomacular interface changes occurring after laser in situ keratomileusis may predispose certain myopic eyes to form a macular hole. Nevertheless, there are not enough hard data in the literature to determine if these are just myopic holes that would have developed anyway regardless of LASIK.
OCT before LASIK may be helpful to identify those eyes at risk for the development of a macular hole. Chan et al have recently introduce the concept of a stage 0 macular hole based on OCT observations of the vitreoretinal interface in fellow eyes of patients with unilateral idiopathic macular holes, and to evaluate the subsequent risk of progression to a full thickness macular hole. In a retrospective observational case series of 94 patients with a unilateral stage 2, 3, or 4 full thickness macular hole. They found that in 27 (28.7%) of 94 clinically normal fellow eyes, OCT detected an abnormality of the vitreoretinal interface but normal foveal anatomy.
Eyes with severe and moderate vitreoretinal abnormalities seemed to share characteristic features on OCT that increased their risk of macular hole development (stage 0 macular hole). Univariate analysis revealed that the presence of a stage 0 macular hole was significantly associated with an almost sixfold increase in the risk of macular hole formation. They concluded that a stage 0 macular hole has a normal biomicroscopic appearance clinically, but has salient features on OCT as a result of oblique vitreous traction. Optical coherence tomographic findings consist of a normal foveal contour and normal retinal thickness and must include the presence of a preretinal, minimally reflective, thin band inserting obliquely on at least one side of the fovea. The presence of a stage 0 macular hole in the fellow eye is a significant risk factor for the development of a second macular hole.
An important limitation of our study is that, owing to its retrospective nature, OCT was not performed before LASIK. In addition, follow up was not consistent and it is possible that patients who developed a macular hole after LASIK were seen by other ophthalmologists outside of our institutions. Thus, we did not attempt to determine the incidence of macular hole formation after LASIK.
In summary, we present 14 eyes of 13 patients with no presurgical sign of a macular hole, which developed a full thickness macular hole after laser in situ keratomileusis. Our study shows that vitreoretinal surgery can be successful in restoring vision for most myopic eyes with a macular hole after LASIK. Vitreoretinal interface changes may have a role in macular hole formation after LASIK for the correction of myopia. Future prospective investigation involving a large number of myopic eyes with ultrasonic or ocular coherence tomographic studies may be valuable for determining vitreoretinal interface changes before and after LASIK.
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