Fifteen years have passed since the first published case series of human eyes after LASIK.1 Although LASIK is a more invasive procedure than photorefractive keratectomy (PRK) and the cornea is exposed to more possible risks (eg, flap-related complications and ectasia),2,3 it changed the trends in refractive surgery and has become the most popular refractive technique for the correction of ametropia4 over the past decade.
To our knowledge, there are few long-term postoperative LASIK studies, and none exceed 6 years' followup.5"7 We present one of the first LASIK-treated patients who participated in the first worldwide LASIK trial in Crete, Greece, 15 years after unilateral surgery using a first-generation microkeratome and excimer laser.
A 40-year-old woman underwent LASIK in the left eye for myopia in July 1991. Ocular history was unremarkable. Preoperative examination included slit-lamp microscopy, uncorrected visual acuity (UCVA), Snellen best spectacle-corrected visual acuity (BSCVA), manifest and cycloplegic refractions, intraocular pressure (IOP), corneal topography (Corneal Analysis System version 2.104; EyeSys Laboratories Ine, Houston, Tex), and optical pachymetry of the central cornea. Uncorrected visual acuity was counting fingers in both eyes. Best spectacle-corrected visual acuity was 20/32 with -7.00 -1.25 X 149? in the right eye and 20/100 with -8.75 -3.75 X 025? in the left eye. Central keratometric measurement was 43.88/44.95 D and 43.75/46.25 D in the right and left eye, respectively. Central corneal thickness was 534 pm and 530 pm in the right and the left eye, respectively.
The patient was fully informed regarding the experimental nature of the procedure, as well as possible intra- and postoperative complications, and gave written informed consent in accordance with institutional guidelines and the Declaration of Helsinki.
The eye was anesthetized with topical oxybuprocaine hydrochloride 4 mg/mL eyedrops (Novesin 0.4%; CibaVision, Embrach, Switzerland [formerly Dispersa AG, Hettlingen, Switzerland]), one drop every 5 minutes for a total of three drops before surgery. Peribulbar anesthesia was then administered (2 to 4 cc lidocaine hydrochloride 20 mg/mL [Xylocaine 2%; AstraZeneca, Sodertalje, Sweden]). A Barraquer eyelid speculum (Katena Products Ine, Den ville, NJ) was placed, and the eye was cleaned with normal saline. A nasally based, 150-pm thick corneal flap was made with a Draeger's lamellar rotor keratome (Storz Instruments GmbH, Heidelberg, Germany) using a 0.15-mm spacer. This rotor keratome was semiautomatic and operates with a rotational mode of its blade. During microkeratome suction fixation, IOP was raised to 60 mmHg.
Following formation of the corneal flap, the microkeratome with its suction ring was removed and the flap reflected nasally. The corneal bed was ablated with a 193-nm excimer laser (MEL 60; Carl Zeiss M?dit?e, Heroldsberg, Germany), beam flu enee at the cornea of 220 mj/cm2 and a firing rate of 20 Hz, with a 5-0 mm ablation zone. We used the PRK algorithm that was programmed with the machine. No astigmatic correction was performed, and attempted correction was 10.00 D (estimated maximum ablation depth of 83 pm). The automated 4.9-mm diameter, computer-controlled, contracting iris diaphragm of the unit, with its incorporated suction ring, was placed on the corneal bed and the intended correction was entered into the module. Before ablation, beam quality was checked on photographic paper.
After excimer laser ablation, the bed was irrigated with normal saline for aproximately 5 to 10 seconds. The corneal bed and inner surface of the flap were dried with an air pump, and the corneal flap was reflected back to its original position. At the end of the surgery, 3 mg tobramycin 0.3% and 1 mg dexamethasone 0.1% (Tobradex; Alcon Laboratories Ine, Ft Worth, Tex) and tropicamide 1 mg/mL eye drops (Mydriatieum; Novartis Ophthalmics AG, Basel, Switzerland [formerly Dispersa]) were instilled. One milliliter of 40 mg of methylprednisolone acetate was injected into the sub-Tenon's space, and a therapeutic bandage soft contact lens was used for 48 hours after surgery. The entire procedure was performed under the excimer laser surgical microscope.
The patient was examined every 24 hours for the next 5 days. The patient received antibiotic/steroid combination eye drops 4 times a day for 4 weeks. The early postoperative course was uneventful.
Follow-up was scheduled at 1 day, 2 weeks, 1,3, and 6 months, and 1 year postoperatively. Full refraction, slitlamp, and topographic examination (Corneal Analysis System for the first postoperative year and last follow-up with the Technomed C-Scan [Technomed GmbH, Baesweiler Germany]) were performed at each visit.
Figure 1. Topography showing preoperative top left) right untreated eye, top right) LASI K-tre ate d left eye, and at last followup 15 years after LASIK, bottom left) untreated right eye, and bottom right) LASIK-treated left eye.
Figure 2. Topography shows left) preoperative, middle) 2 months postoperative and right) last follow-up 15 years after LASIK.
Six months postoperatively, UCVA was counting fingers and BSCVA was 20/80 with -3.75 -3.00 X 020° in the left eye. Manifest refraction, UCVA, BSCVA, and topographic findings were stable during the next 6 months. Fifteen years later, UCVA was counting fingers in both eyes. Best spectacle-corrected visual acuity was 20/32 with -7.75 -1.50 X 130? in the right eye and 20/80 with -4.25 -2.75 X 010? in the left eye, and topographic stability was observed (Figs 1 and 2).
Confocal microscopy analysis was performed with a modified confocal scanning laser ophthalmoscope (HRT II Rostock Cornea Module; Heidelberg Engineering Ine, Vista, Calif). Qualitative evaluation of the images was performed with special attention directed at the subepithelial nerve plexus and flap interface. Corneal images revealed a normal epithelium with flat superficial cells, polygonal intermediate cells, and cylindrical basal cells. Images of the subbasal and subepithelial nerve plexus exhibited a regenerated nerve plexus that appeared normal with slightly increased tortuosity (Fig 3A). Keratocytes' bright nuclei against a dark background were observed just anterior to the flap interface (Fig 3B), whereas keratocyte activation, increased scattering, and highly reflective particles were observed at the flap interface (Fig 3C). Keratocyte density at the anterior flap seemed higher compared to the deeper stromal layers.
Figure 3. Confocal scanning laser microscopy images demonstrate A) regenerated subepithelial nerve plexus, B) anterior stroma with increased keratocyte density and activation, and C) increased scattering and highly reflective particles at the flap interface.
On a current overall satisfaction scale of 1 to 5, the patient was considered to be happy with the results (score of 4).
Fifteen years have passed since the first published case series of human eyes treated with LASIK,1 although long-term follow-up studies of LASIK-treated eyes do not exceed observation over 6 years.5 During these years, an impressive improvement in microkeratome and excimer laser technology has led to significant decrease in intraoperative and early postoperative complications. Despite these improvements, long-term postoperative complications, with a major interest in the possible effects of such an invasive technique on ocular structures, has not yet been investigated.
In the present case report, long-term complications were not observed. Refractive and topographic stability were achieved 6 months after LASIK treatment. Previous long-term follow-up studies of myopic LASIK have shown moderate refractive predictability and stability in attempted higher corrections.5"7 Similarly, we found moderate predictability in the refractive outcome with a trend for refractive and topographic stability after the sixth postoperative month despite the large attempted correction (-10.00 D) and estimated residual corneal stroma (<300 pm). Furthermore, increased scattering and presence of debris was observed at the flap interface even after 15 years.
Unexpectedly, the patient was satisfied with the final outcome despite considerable residual compound myopic astigmatism. We believe patients with high degrees of ametropia and amblyopia (such as the patient in the current study) are more receptive to such outcomes.
To our knowledge, this is the longest (15 years) LASIK follow-up case report in the literature. Late postoperative complications related to the surgery were not observed; conversely, refractive stability was observed after the sixth postoperative month?
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