Low-fluence photodynamic therapy for early onset choroidal neovascular membrane following laser in situ keratomileusis.

Dear Editor,

Despite being a technically near-perfect procedure, laser refractive surgery is not without attending complications involving the anterior and posterior segments, which include retinal tears and breaks, retinal detachment, vitreous hemorrhage, macular hemorrhage, subretinal hemorrhage, macular holes and, rarely, choroidal neovascular membrane (CNVM).[1]

Recently, low-fluence photodynamic therapy (PDT) has been shown to be effective and safe for the treatment of myopic CNVM.[2] Intravitreal injections of anti-vascular endothelial growth factor (VEGF) have also been shown to be effective therapeutic options.[3]

We report the successful management of subfoveal CNVM that appeared 2 weeks following laser-assisted in situ keratomileusis (LASIK) for high myopia.

A 25-year-old lady with high myopia who underwent uneventful LASIK complained of sudden diminution of vision in the left eye (OS) 2 weeks after the procedure. Her preoperative best-corrected visual acuity (BCVA) had been 20/20 OU, with a refractive correction of –8.00 in the right eye (OD) and –8.25, –0.5 × 105° OS. One week after the LASIK procedure, an uncorrected VA of 20/20 OU was recorded.

On presentation 2 weeks post-LASIK, her BCVA was 20/20 OD and 20/400 OS. Slit lamp examination showed normal anterior segment OU. Fundus examination showed a localized grayish subfoveal CNVM with overlying retinal edema OS [Fig. 1a]. Fundus fluorescein angiography (FFA) confirmed a subfoveal classic CNVM with increasing late leakage [Fig. 1a]. Optical coherence tomography (OCT) of the macular area showed subfoveal fibrovascular lesion with a central macular thickness of 342 μm OS [Fig. 1b].

Figure 1a

Fundus photograph and fluorescein angiography of the left eye at presentation showing myopic fundus with active subfoveal classic choroidal neovascular membrane and late leakage

Figure 1b

Optical coherence tomography (horizontal and vertical) of left eye macula showing subfoveal choroidal neovascular membrane with edema of the overlying neurosensory retina

Low-fluence PDT with Verteporfin (Visudyne, Novartis Pharma AG, Switzerland) at a standard dosage of 6 mg/m2 was performed using a diode laser (Visulas 690s, Carl Zeiss Meditec, Inc., Dublin, CA), with a radiant exposure of 25 mJ/cm2 at an intensity of 300 mW/cm2 over 83 s. Three sittings of low-fluence PDT at 3-monthly intervals were required for complete regression of CNVM.

Low-fluence PDT resulted in complete regression of the CNVM, as documented by FFA and OCT [Fig. 2a and b]. Her BCVA improved to 20/40 OS from 20/400 at 6 months follow-up.

Figure 2a

Fundus photograph and fluorescein angiography of the left eye following treatment with low-fluence photodynamic therapy showing regressed subfoveal choroidal neovascular membrane with late staining

Figure 2b

Optical coherence tomography (horizontal and vertical) of left eye macula following treatment with low-fluence photodynamic therapy showing regressed subfoveal choroidal neovascular membrane

Al Dhibi et al., described a case of early CNVM in a young myope, 2 weeks following LASIK.[4] However, the initial diagnosis of central serous chorioretinopathy (CSCR) and use of systemic steroids in this case makes the real diagnosis and response to PDT uncertain.

Aravelo et al., have described five cases of subfoveal CNVM following LASIK with mean onset of 45.6 months, treated with PDT.[5]

The induction of high intraocular pressure up to 60 mmHg with the microkeratome suction ring, up to 4 mm posterior to the limbus, exerts posterior traction and compression. This may have triggered the stretching and breaks within the Bruch's membrane in the macula, consequently resulting in the genesis of a CNVM.[1]

CNVM can be triggered by LASIK in patients with high myopia, with an onset as early as 2 weeks following LASIK, without other predisposing macular disorders. Patients should be informed and made aware of this possible complication.

However, when they do occur, CNVM may be successfully managed with low-fluence PDT, as an alternative to or in combination with intravitreal anti-VEGF injections.