The first case of ectasia development after LASIK was reported in 1998, and it was not until after 2000 that a significant number of cases had been described.1 Keratectasia after excimer laser is a potentially devastating complication with visual morbidity that, in some cases, requires penetrating keratoplasty.2,3 The etiology and biomechanical changes that induce keratectasia after refractive surgery are unknown.4 Possible risk factors for the development of ectasia following excimer laser have been identified in the literature2,5,6 and include high myopia, reduced preoperative corneal thickness, reduced residual stromal bed after laser ablation, and asymmetrical corneal steepening (forme fruste keratoconus), but none of these characteristics definitively predict development of ectasia. Ectasia can develop in eyes with no identifiable risk factors.2,5,6
Holland et al7 reported cases of ectasia after photorefractive keratectomy (PRK) due to retreatment or unrecognized keratoconus.
Malecaze et al8 recently reported a case of corneal ectasia after PRK in a patient with forme fruste keratoconus. Koch9 suggested that data be reported for patients who develop keratectasia after excimer laser; therefore, we report a patient who developed bilateral corneal ectasia after uneventful PRK with asymmetric bowtie topography and suspicion for forme fruste keratoconus in the right eye.
A 35-year-old man underwent refractive surgery in August 2005. He had not worn soft contact lenses for 4 months. Ocular history was unremarkable. Initially, he denied family history of ocular disorders, particularly keratoconus. Uncorrected visual acuity (UCVA) was 20/200 in the right eye and 20/100 in the left eye. Best spectacle-corrected visual acuity (BSCVA) was 20/20 with -3.00 -1.50 X 20 in the right eye and -3.00 -2.00 X 160 in the left eye. The patient's refraction was stable.
Preoperative central corneal thickness was 497 ??? in the right eye and 511 pm in the left eye, and the peripheral corneal thickness was 626 pm and 647 pm, respectively. Central keratometry was 43.25/45.00 in the right eye and 43.25/45.50 in the left eye. Preoperative topography with the Orbscan II (Bausch & Lomb, Rochester, NY) is shown in Figures 1 and 2 . The anterior elevation map shows 7.85 mm/43.00 diopters (D) with a differential of 0.014 in the right eye and 7.81 mm/43.20 D with a differential of 0.012 in the left eye. The posterior elevation map shows 6.15 mm/54.80 D with a differential of 0.021 mm in the right eye and 6.14 mm/54.90 D with a differential of 0.026 mm in the left eye. Because of asymmetry of the astigmatism, forme fruste keratoconus was suspicious, mostly in the right eye. No clinical signs of keratoconus were found on slit-lamp examination.
Bilateral PRK was performed uneventfully, removing 8.0-mm diameter of corneal epithelium with an excimer laser (Technolas 217; Bausch & Lomb) after 30 seconds of 30% alcohol exposure. The attempted correction was ?3.00 ?1.50 X 20 in the right eye and -3.00 -2.00 X 165 in the left eye. The ablation zone diameter was 5.0 mm and 5.5 mm, respectively. The calculated total ablation depth was 67 pm in the right eye and 70 pm in the left eye. After 5 days, the epithelium was fully recovered and the soft contact lenses were removed. Uncorrected visual acuity was 20/50 bilaterally.
Figure 1. Preoperative topography of the right eye.
Figure 2. Preoperative topography of the left eye.
Figure 3. Topography of the right eye 9 months after photorefractive keratectomy.
Figure 4. Topography of the left eye 9 months after photorefractive keratectomy.
Two weeks after surgery, the patient experienced loss in visual acuity in both eyes. Uncorrected visual acuity was 20/80 in the right eye and 20/200 in the left eye. Objective refraction was impossible to obtain. Slit-lamp examination showed corneal thinning in both eyes. The patient was required to wear rigid contact lenses to achieve a final BSCVA of 20/25 in both eyes.
Six months after surgery, topographic findings were consistent with the diagnosis of corneal ectasia after PRK. Nine months after PRK, UCVA was 20/70 in the right eye and 20/80 in the left eye. We found a scissoring reflex on retinoscopy, corneal thinning, and mild prominent corneal nerves in both eyes. Both topographic and clinical findings (Figs 3 and 4) persisted with the diagnosis of keratectasia in both eyes. Best spectacle-corrected visual acuity with rigid contact lenses was 20/20 bilaterally.
Corneal ectasia after PRK is extremely rare. In our case, the patient did not have tangible risk factors except for asymmetric bowtie topographies.
Ectasia after LASIK has been described to occur within weeks and up to 45 months after the primary surgery.10 Our patient presented only 2 weeks after surgery with findings consistent with ectasia. One possibility for ectasia-like findings is that the healing of corneal epithelium during the early postoperative period may result in an artificial and temporary hyperflattening of the corneal contour11; unfortunately, we did confirm the diagnosis of ectasia after PRK in our patient.
Photorefractive keratectomy has proven to be a safe, simple, and effective procedure to correct low to moderate myopia, and with proper patient selection can be considered safer compared to other refractive procedures.1213 Alio et al12 reported few complications after PRK in 3000 eyes. Over the past few years, mitomycin C treatments have gained popularity to reduce haze and allow greater surface ablations.1415 Using our case as an example, refractive surgeons should be aware of the possibility of corneal ectasia occurrence in low myopia, low ablation, and with enough residual stromal bed after ablation even when a corneal flap is not performed.
After clinical ectasia presented in our patient, we further questioned him regarding other risk factors. He advised he was a habitual eye rubber in both eyes since childhood. As Comaish et al6 proposed, surgeons should be aware of the potential for development of progressive keratectasia after excimer laser in chronic eye rubbers.
Binder10 recommends investigating clinical or topographic evidence of keratoconus or forme fruste keratoconus in a family history before evaluating the ablation used. After the ectasia occurred, we examined the patient's family and found a sister with clinical and topographic keratoconus. Some surgeons avoid performing refractive surgery in patients with a family history of keratoconus. As proposed by Rabinowitz,16 we considered family history an important risk factor in the algorithm to prevent ectasia. Therefore, we recommend avoiding refractive surgery, even surface techniques such as PRK, in patients with a family history of keratoconus.
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