Laser in situ keratomileusis (LASIK) has become the refractive surgical technique most frequently used for the correction of ametropias. In the last few years, several reports of posterior pole complications after this procedure have been published.1–16 Even though a direct cause-effect relationship between LASIK and these complications cannot be confirmed, some authors have suggested that sudden changes in intraocular pressure (IOP) during suction ring use could induce vitreoretinal alterations in predisposed patients.1,3–5,7 To the best of our knowledge, a complete symptomatic vitreous detachment after LASIK has not been previously described. We report a case of a moderate myopic patient who developed an acute complete posterior vitreous detachment (PVD) in both eyes 1 day after LASIK retreatment.
A 47-year-old woman underwent bilateral LASIK for the correction of myopia and astigmatism in April 2002. Uncorrected visual acuity (UCVA) was 20/160 in the right eye and 20/200 in the left eye, and best corrected visual acuity (BCVA) before surgery was 20/40 in both eyes with a correction of – 5.50 + 3.25 × 70 diopters (D) and – 5.25 + 2.75 × 90° D, respectively. Preoperative biomicroscopic examination was normal in both eyes and IOP was 17 mm Hg in the right eye and 18 mm Hg in the left eye. Pachimetry (OcuScan, Alcon) demonstrated a corneal thickness of 555 μm in the right eye and 566 μm in the left eye. Funduscopic examination performed by a vitreoretinal specialist showed normal optic nerves and mild diffuse attenuation of retinal pigment epithelium bilaterally. A partial asymptomatic PVD was found in the left eye.
Surgery was performed according to a standard previously published technique.17 One day after surgery, the UCVA was 20/80 in the right eye and 20/60 in the left eye and BCVA was 20/40–2 in both eyes with a correction of –0.50 + 1.50 × 90 D and –1.00 + 1.25 × 90 D, respectively. Corneal flaps were well placed and the stromal interfaces were clear. No alterations were found in slitlamp examination. Two months later UCVA remained unchanged and BCVA was 20/40–2 in right eye and 20/40 in left eye with a correction of –0.50 + 2.50 × 100 D and –1.75 + 1.50 × 100 D, respectively. Slitlamp examination performed at this time revealed clear corneas, with deep and quiet anterior chambers. Because the patient needed to improve her visual acuity and expected to be able to avoid the use of spectacles or contact lenses, it was decided to correct the residual refractive error. A new corneal pachymetry performed before surgery revealed a corneal thickness of 498 μm in the right eye and 507 μm in the left eye. No fundus examination was done before retreatment.
At this opportunity, a new corneal flap of 180 μm was created applying the suction ring again. One day after retreatment the patient reported seeing through a “mobile hazy film” with both eyes. UCVA was 20/50–2 in the right eye and 20/50 in the left eye and BCVA was 20/40 with a correction of –0.50 D and –0.50 + 0.50 × 90 D, respectively. Biomicroscopic examination revealed clear corneas, normal flaps, and quiet and deep anterior chambers, with normal iris and lens in both eyes. Fundus examination showed complete bilateral vitreous detachment. Optic nerves and retinas were normal. Fluorescein angiography performed to rule out macular disease was normal in both eyes. A kinetic ultrasound performed at this time confirmed the clinical findings (Figure 1). Two weeks later UCVA was 20/40–1 in both eyes, and no changes were noted in the posterior pole. After 10 months of follow-up, visual acuity, symptoms, and vitreous alterations remained unchanged.
Posterior vitreous detachment can be defined as a separation between the posterior vitreous cortex and the internal limiting lamina of the retina, which can be localized, partial, or total.18 Conditions associated with PVD include aphakia, inflammatory disease, or trauma; also, its prevalence increases with axial length of the eye and patient's age.19,20 We, as well as other authors,5,6 have previously reported PVD after LASIK. However, to the best of our knowledge, this is the first report of acute complete bilateral vitreous detachment after LASIK retreatment.
This is a case of entire vitreous detachment in both eyes occurring 1 day after bilateral LASIK retreatment. Both eyes had moderate myopia and astigmatism, and a partial asymptomatic PVD was noted before treatment only in the left eye. Importantly, that PVD was symptomatic in both eyes immediately after the surgery. We believe the total PVD occurred after retreatment because preoperative vitreous examination was normal in the right eye, and only a partial asymptomatic PVD was found in the left eye. In addition, the patient did not mention any alteration preoperatively, when she was wearing contact lenses, or after the first refractive procedure. However, because no funduscopic examination was carried out between surgeries, we could not determine whether a complete vitreous detachment was present before retreatment. Although final visual acuity in this patient was good, visual disturbance in both eyes continued to be present after 10 months of follow-up.
Many authors have suggested that acoustic shock waves and quick variations in IOP might provide significant stress to the globe, leading to posterior pole complications.1,4,5,9,21 In our case, in both surgeries the suction ring was applied for about 10 seconds, and the IOP was verified to be greater than 65 mm Hg with a Barraquer tonometer. Previous studies carried out by our team5 as well as other colleagues21 support our belief that sudden changes in IOP, related to suction ring use, may have generated brisk alterations in vitreous shape, leading to vitreous detachment in our patient. Our group published clinical and experimental studies of vitreoretinal alterations post LASIK that also back up this theory.5 In this study, PVD was observed after LASIK surgery in 4% of eyes with low myopia and in 24% of eyes with high myopia. Experimentally, we found PVD in 20% of pig eyes immediately after suction ring application for 30 seconds. Our study revealed that the use of suction ring increased clinical and ultrasonographic vitreoretinal changes and that the prevalence of PVD was higher in the high myopic group. Recently, Mostafavi et al.21 reported similar preliminary findings in a study of vitreoretinal changes associated with suction ring application in cadaveric porcine eyes.
These findings along with the growing number of reports about posterior pole complications after LASIK should raise awareness about the possibility that this technique might increase the risk of vitreoretinal alterations in predisposed patients. In experimental studies performed by our team and presented at the annual meeting of ARVO in 2000 (Abstract 1834-B81), we found that the animals in which the suction ring was applied progressively did not develop PVD. We believe that the use of new devices allowing a slow progressive suctioning of the eye, which avoids sudden IOP changes, could reduce the possibility of PVD and posterior pole complications after LASIK surgery.
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