Non-arteritic ischemic optic neuropathy (NAION) has been reported after laser in situ keratomileusis (LASIK) performed with a microkeratome flap (1,2). Its occurrence has been attributed to the pressure elevation caused by the suction ring. The suction ring placed during hyperopic LASIK transiently elevates the intraocular pressure (IOP) to levels exceeding 65 mm Hg.
We examined a 53-year-old man who developed unilateral NAION after bilateral simultaneous uncomplicated hyperopic LASIK in which flap creation was performed using the IntraLase femtosecond laser (IntraLase Corp., Irvine, CA) with a low-pressure suction ring. To the best of our knowledge, NAION has not been reported in this setting.
Preoperative refractive errors were +5.50 +0.50 Ă—105 for the right eye and +5.25 +0.50 Ă—90 for the left eye with best-corrected visual acuities of 20/20 in both eyes. Preoperatively, IOPs were normal and family history was negative for glaucoma. The LASIK surgeon reported that results of a preoperative dilated fundus examination was unremarkable except for small optic discs and cup/disc ratios.
The procedure was uneventful. In each eye, the IntraLase femtosecond laser was used to create superiorly hinged flaps of 110 μm thickness, and stromal ablation was performed. Corneal topography after LASIK surgery revealed a hyperopic LASIK ablation pattern.
On the first postoperative day, best-corrected visual acuities were 20/20 in the right eye and 20/200 in the left eye. The right optic disc was normal, and the left optic disc was edematous. There was a relative afferent pupillary defect in the left eye. Visual field examination showed a dense nerve fiber bundle defect in the left eye (Fig. 1).
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FIG. 1: On postoperative day 1 after bilateral hyperopic LASIK procedures with femtosecond flap creation, fundus photographs (A) show left segmental optic disc edema, and visual fields (B) show a corresponding left eye defect.
In the two reported cases of NAION after LASIK surgery (1,2), flap creation was performed using a mechanical microkeratome, with an associated sudden increase in IOP to 60-70 mm Hg, followed by a rapid IOP decrease upon suction release. Our patient is unusual because during IntraLase laser treatment, the IOP did not exceed 30-40 mm Hg (3,4). The mechanism of NAION under these circumstances is unknown.
Ahmet Maden, MD
Safiye Yilmaz, MD
Nazife Sefi Yurdakul, MD
Department of Ophthalmology Izmir AtatĂ¼rk Training and Research Hospital Izmir, Turkey [email protected]
REFERENCES
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