Retinal detachment after laser in situ keratomileusis.

PURPOSE: To report characteristics and outcome of rhegmatogenous retinal detachment (RRD) after laser in situ keratomileusis (LASIK) for myopia.
MATERIALS AND METHODS: A retrospective chart review of patients who presented with RRD after myopic LASIK over a 10-year period.
RESULTS: Fourteen eyes were identified with RRD. Of these, two of 6112 LASIK procedures were from our center. The mean age of patients with RRD was 35.43 years. The mean interval of RRD after LASIK was 37.71 months (range, 4 months to 10 years). The macula was involved in eight eyes and spared in six eyes. Retinal breaks included a macular hole in two eyes, and giant tear in two eyes. Multiple breaks (>2 breaks) occurred in 6 cases. Pars plana vitrectomy (PPV) was performed in 3 (21.4%) eyes, a scleral buckle (SB) was performed in 4 (28.5%) eyes and 7 (50%) eyes underwent combined PPV and SB. Mean follow-up was 15.18 months (range, 1 month to 7 years). The retina was successfully attached in all cases. The final visual acuity was 20/40 or better in 7 (50%) eyes, 20/40 to 20/60 in 4 (28.5%) eyes, and 20/200 or less in 3 (21.4%) eyes. Poor visual outcome was secondary to proliferative vitreoretinopathy, epiretinal membrane, macular scar and amblyopia.
CONCLUSION: The prevalence of RRD after LASIK was low at our institute. Anatomical and visual outcomes were acceptable in eyes that were managed promptly. Although there is no cause-effect relationship between LASIK and RRD, a dilated fundus examination is highly recommended before and after LASIK for myopia.

INTRODUCTION

Laser in situ keratomileusis (LASIK) has become increasingly popular because of the general lack of postoperative pain, lower incidence of corneal haze and scarring, favorable outcome for eyes with more than -6 diopters (D) of myopia, and a rapid improvement of uncorrected visual acuity (UCVA) with LASIK compared to photorefractive keratectomy.1–6 Although several clinical studies have demonstrated the efficacy and predictability of LASIK in reducing low to high myopia, this procedure may lead to various posterior segment complications including retinal tears, retinal detachments (RD), retinal hemorrhages, macular holes (MH) and choroidal neovascular membranes (CNVM).7–21

According to the medical literature, the frequency of rhegmatogenous retinal detachment (RRD) after LASIK is reported to be 0.08%18 to 0.25%.7 The objective of this study is to determine its occurrence of RRD after myopic LASIK over a 10-year period in a busy LASIK center and cases referred from elsewhere in the Middle East for treatment and to present the clinical characteristics and outcomes of RRD after LASIK.

MATERIALS AND METHODS

After approval by the research committee, and human ethics committee, the charts for patients who were presented with RRD after LASIK at King Khaled Eye Specialist Hospital from 1997 to 2007 were reviewed and the total number of LASIK procedures performed at our institute in that period was calculated. The data collected included patients’ age, sex, prior ocular diseases including, myopia, and history of RD in the fellow eye, retinal surgery, positive family history of RD and previous history of prophylactic laser interval of RD diagnosis after LASIK, RD characteristics including, location, type and number of retinal breaks, macular involvement, presence of posterior vitreous detachment (PVD), presence of proliferative vitreoretinopathy (PVR), vitreous hemorrhage, cataract, hypotony and choroidal detachment. The type of procedure done for RD repair was reviewed. Final outcome and causes of poor visual outcome were also investigated including the presence of vitreous hemorrhage, PVR, cataract, epiretinal membrane (ERM) and chronic RD.

RESULTS

Twelve eyes underwent LASIK elsewhere and two eyes (1 patient) underwent LASIK at our institute. The total number of LASIK procedures performed at our institute from 1997 to 2007 was 6,112 providing an incidence of RRD of 0.0003% (2/6112). Table 1 outlines the characteristics of patients with RD after LASIK. Nine males and three females had the mean age of 35 years. Best corrected visual acuity at presentation ranged between LP to 20/20 (median: 20/60). The interval of RRD after LASIK ranged between 4 months to 10 years (mean 37.71) months being ≤6 months in three cases, >6 months to 1 year in four cases and >1 year in seven cases. The macula was spared in six eyes (42.9%) and was involved in eight eyes (57.1%). Retinal breaks occurred temporally and superotemporally in 78.5% of eyes, with were multiple breaks (i.e., >2 breaks) occurring in 42.9% of eyes. MH was present in two cases while giant retinal tear occurred in two eyes. PVD was present in nine (75%) eyes, PVR in one (7.1 %) eye and choroidal detachment in one (7.1%) eye.

Table 1

Characteristics of patients with RD after LASIK

The initial management was pars plana vitrectomy (PPV) in three eyes (21.4%), scleral buckle (SB) in four eyes (28.5%) and seven eyes (50%) underwent PPV with SB. Intraocular gas tamponade was performed in all primary RRD cases in which PPV was indicated with or without SB. Silicone oil injection was performed in one case of recurrent RRD with PVR.

The most common postoperative complication was cataract. Five eyes (35.7%) of four patients underwent phacoemulsification with posterior chamber intraocular lens implantation resulting in visual improvement. Recurrent RRD occurred in three eyes (21.4%) and was secondary to a new break, recurring MH and after silicone oil removal, respectively. Other complications noted were PVR (one eye) and ERM (one eye). The follow-up range was 1 month to 7 years (mean 15.18 months). Retinal attachment was achieved in all cases. The final VA was 20/40 or better in seven eyes (50%), < 20/40 to 20/60 in four (28.5%) and 20/200 or less in three eyes (21.4%). Visual acuity improved in 10 eyes. Causes of poor visual outcome were attributed to vitreoretinopathy (one eye), ERM (one eye), macular scar (one eye) and amblyopia (one eye).

DISCUSSION

LASIK has become the procedure of choice for the surgical correction of myopia. With the increase in the number of LASIK procedures performed there have been reports of RRD, postoperatively.718 In this retrospective study we found the incidence of RRD after LASIK was 0.0003% at our center which is lower than previous studies.716–1921 The difference in rates is likely due to our preoperative protocol of a dilated fundus examination with scleral depression (if possible) and referral to a vitreoretinal surgeon for the treatment of any predisposing retinal lesion such as a horseshoe tear with vitreous traction, acute PVD with retinal break or lattice degeneration. Additionally surgeons at our center perform LASIK only on patients who have 8 D or less of myopia.

The association of myopic LASIK to RRD remains controversial. Arevalo et al.22 proposed that the mechanism for development of peripheral retinal tears or macular injury during LASIK procedure was due to vitreous traction and deformity induced by anterior-posterior compression and expansion. Mostafavi et al.23 believed that changes in axial length during LASIK may translate into changes in vector forces at the vitreoretinal interface, leading to the formation of PVD retinal breaks and RRD.

Flaxel et al.24 measured IOP, anterior chamber depth, and axial length before and after application of a suction ring (Moria, Antony, France) in eight human cadaver eyes and found that axial length increases whereas anterior chamber depth did not change. Based on their findings, Flaxel et al.24 reported that LASIK has the potential to aggravate preexisting retinal pathology and precipitate an acute PVD or retinal tear in regions of pre-existing retinal pathology.

Alternately, retinal breaks and detachments can occur due to the natural history of myopic eyes and are an expected risk for myopes, regardless of previous LASIK.25–27 Faghihi et al.28 found that males, older age and higher preoperative myopia were significantly related to the incidence of RRD after LASIK. Faghihi et al.28 reported that of the 49 eyes that had RRD, 23.9% had a manifest refractive spherical equivalent (MRSE) of -4.99 D, MRSE was between -5.0 to -9.99 D in 32.6% and 43.5% of eyes had MRSE of -10.0 D or higher.25 The yearly incidence of RRD was 0.022% in eyes with MRSE up to -4.99 D, 0.025% in eyes with MRSE of -5.00 D to -9.99 D and 0.091% in eyes with MRSE of -10 D or higher.28 Salazar et al.29 reported that RD in patients who had previous myopic LASIK had similar characteristics as myopes do did not undergo refractive surgery. Arevalo et al.18 reported 33 cases of RRD after LASIK of which 10 (30.3%) cases occurred less than 6 months and 20 (60.6%) cases occurred 12 months or more after LASIK. The yearly occurrence of RRD after LASIK suggests a cause-effect relationship. Cases where RRD developed 12 months or more after LASIK suggest that a PVD may have developed at a later stage.

In the current study three cases of RRD occurred less than 6 months after LASIK. Owing to the short interval, we believe that LASIK has a direct impact on the retina that causes RRD. However, we cannot prove this relationship from the data in the current study due to the retrospective nature of the study, the small sample size and the lack of biophysical modeling.

We found the most frequent site for retinal breaks was the superotemporal quadrant which is similar to non-traumatic phakic RRD.1718 PVD was present in nine (75%) eyes; however, we were not certain if PVD occurrence was present before or after LASIK. PVD is a known risk factor for retinal tears/detachments25–27 and LASIK has been shown to induce this change.3031 For example, Mirshahi et al.30 reported a 9.5% incidence of new-onset PVD after LASIK which was confirmed by B-scan. Similarly Luna et al.32 reported a 2% incidence of new PVD after LASIK for low myopia which increased to 24% in eyes with a MRSE greater than - 6.00 D.

Our study showed BCVA after RD repair was 20/30 which is similar to or better than reported studies [Table 2]. The cause of poor final visual outcome in our series was similar to the previous reported studies which included factors such as PVR, ERM, macular scar and amblyopia [Table 2].

Table 2

Incidence and clinical features of retinal detachment after laser in situ keratomileusis in the current and previous studies

The limitations of our study include the use of retrospective data, small sample size and failure to obtain pre-LASIK fundus examination, pre-LASIK refraction, and correlation of the magnitude of myopia to the occurrence of RRD. Some of this data were not available to us since the most of the patients in this series were referred from other institutions

In conclusion, the incidence of RRD after myopic LASIK is low. In cases of RRD post-LASIK, prompt treatment results in good visual outcomes. Although our study could not prove a cause and effect relationship between LASIK and RRD, the possibility of RRD should be discussed with the patient during the preoperative assessment. The short interval between LASIK and RD requires further study to assess the impact of suction ring on the retina in the myopic eye. Pre- and post-LASIK dilated fundus examinations are highly recommended and appropriate cases should be referred to a vitreoretinal specialist.