Clinicopathologic Reports, Case Reports, and Small Case Series
November 2001

Corneal Ectasia After Laser-Assisted In Situ Keratomileusis

Author Affiliations



Copyright 2001 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2001

Arch Ophthalmol. 2001;119(11):1714-1716. doi:

Laser-assisted in situ keratomileusis (LASIK) has become the most common surgical option to correct myopia. Certain preexisting conditions are contraindications for LASIK, and they include unstable vision, keratoconus, thin corneas, pregnancy, and autoimmune diseases. A careful evaluation can help select the good candidates and predict which patients will have a guarded outcome. We describe the clinical and histologic features of a patient who underwent penetrating keratoplasty due to progressively worsening vision from corneal ectasia after LASIK.

Report of a Case

A 32-year-old woman came to the Refractive Surgery Center, Wilmer Eye Institute, Baltimore, Md, seeking a second opinion after LASIK was done elsewhere. Her chief complaint was that her vision had worsened since surgery and she could not function anymore with any form of visual aids.

Her ocular history was significant for keratoconus suspected by 2 ophthalmologists but not by the last physician who recommended and performed bilateral simultaneous LASIK. Before LASIK, she wore rigid gas-permeable contact lenses until she became intolerant to those.

During the preoperative evaluation, an autorefractor revealed keratometry readings of 47.75 and 51.75 OD and 49.37 and 55.00 OS. Her manifest refraction revealed a visual acuity of 20/25 OD with −11.25 + 3.75 × 085 and 20/70 OS with −13.00 + 3.75 × 080. Her best-corrected visual acuity with rigid gas-permeable contact lenses was 20/20 OU. Preoperatively, her central corneal pachymetry readings were 511 µm OD and 482 µm OS, as obtained by a scanning slit measurement system (Orbscan Topography; Bausch & Lomb, Inc, Rochester, NY). She underwent full-correction LASIK in both eyes. One month postoperatively, the patient's best-corrected visual acuity was 20/40 OD with −3.25 + 0.50 × 125 and 20/50 OS with −2.25 + 0.75 × 85.

When we first examined the patient, 5 months after the surgery, her best-corrected visual acuity was 20/200 OD with −10.50 + 0.50 × 90 and 20/100 OS with −9.75 + 0.75 × 90. Her central corneal pachymetry reading was 365 µm OU by ultrasonographic pachymetry. Corneal topography revealed central steepening in both eyes (Humphrey Visual Instruments, San Leandro, Calif) (Figure 1). Her keratometry readings, as indicated by the corneal maps, reached 55 and 61 OD and 54 and 58 OS. No posterior corneal curvature measurements were obtained. On slitlamp examination, she had well-centered LASIK flaps with nasal hinges in both eyes. The corneal epithelium was dry centrally and stained with fluorescein. The stroma appeared thin and bulging forward (Figure 2). The lamellar interface appeared clear in both eyes. The rest of the anterior segment, including the anterior chambers, irides, and lenses, appeared normal. Intraocular pressures were 11 mm Hg OU by applanation tonometry. The results of her dilated retinal examination were unremarkable. Despite punctal plugs and the hourly use of preservative-free tears with lubricating ointment at night, her visual acuity continued to deteriorate. Corneal topography revealed that the surface of the right eye was more irregular. A contact lens fit was attempted, but the patient did not believe she could tolerate the lenses. A diagnosis of corneal ectasia was made based on the progressive worsening of the cornea together with central thinning as measured by pachymetry, and penetrating keratoplasty was recommended because the cornea was too thin and dry to tolerate any other intervention. The patient underwent an uncomplicated corneal transplantation (8.0-mm donor size to 7.5-mm recipient size), and corneal tissue was sent for histologic studies (Figure 3).

Figure 1.
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Corneal topography of the right eye after laser-assisted in situ keratomileusis, showing central steepening. S-merid indicates the distance from the vertex (large crosshair) and its location on the semimeridian; CIM, corneal irregularity measure.

Figure 2.
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Slitlamp appearance of the cornea, showing stromal thinning and bulging after laser-assisted in situ keratomileusis, seen best just above the lower pupillary margin.

Figure 3.
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Section of the corneal button showing the edge of the lamellar cut (lower right corner) and a paracentral thin area (periodic acid–Schiff, original magnification ×3).

The light microscopy reveals one margin of the corneal flap with a discontinuity of the Bowman layer and a slanted area of mild scarring (Figure 4). Looking at a central area, there is a faint delineation between the flap and the remainder of the stroma (Figure 5). The flap area has a slight increase in cellularity compared with the remainder of the stroma. Centrally, the cornea, including all layers, measured 317 µm in thickness, and the flap measured 81.5 µm.

Figure 4.
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Discontinuity of the Bowman layer and a slanted area of mild scarring (arrow) at one margin of the corneal flap (periodic acid–Schiff, original magnification ×100).

Figure 5.
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Central area with a faint delineation (arrow) between the flap and the remainder of the stroma (periodic acid–Schiff, original magnification ×160).

Transmission electron microscopy showed the discontinuity of the Bowman layer (Figure 6) and a zone of irregular collagen with a slight increased number of fibrocytes in the plane between the flap and the remainder of the stroma (Figure 7). There was no endothelial damage.

Figure 6.
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One margin of the corneal flap, with discontinuity of the Bowman layer (arrow) and an area of scarring (asterisk) (original magnification ×2200).

Figure 7.
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Central cornea with an area of irregularity of the collagen and an increased number of fibrocytes (between arrows) in a plane between the corneal flap and the remainder of the stroma (original magnification ×8800).


This case represents an example of corneal ectasia after LASIK, for which the underlying risk factors for ectasia appear to be a combination of keratoconus, thin preoperative central corneas, and possibly a lamellar keratectomy.

Several cases of corneal ectasia after LASIK have been reported,15 but only one report1 included pathologic findings. The histologic features of our case echo previous light microscopic features. However, to our knowledge, transmission electron microscopic features have not been previously described. Even though the histopathologic changes are consistent with the clinical findings, it is still the physical properties, strength, and stability of the thin cornea after LASIK that need to be studied to understand why some patients have a guarded outcome. Seitz et al6 studied the posterior corneal curvature changes after LASIK, and concluded that increased negative keratometric diopters and oblate asphericity of the posterior corneal curvature pointed toward early keratectasia after LASIK. Until a better understanding of the biomechanical properties of the corneal deformation is reached, certain general guidelines should be followed. These include performing central corneal pachymetry and corneal topographic imaging in the preoperative evaluation of every potential refractive surgery patient and avoiding LASIK in patients whose final corneal stromal bed thickness is less than 250 µm or who appear to have keratoconus. Finally, corneal deformation and ectasia with a possible need for more corneal surgery, including lamellar or penetrating keratoplasty, should always be included as part of the informed consent.

The pathologic features of corneal ectasia include an interruption of the Bowman membrane with mild anterior cellularity, a thinner stromal thickness, and no endothelial damage.

Corresponding author: Walter J. Stark, MD, The Wilmer Eye Institute at Greenspring Station, 10755 Falls Rd, Suite 110, Baltimore, MD 21093.

Geggel  HSTalley  AR Delayed onset keratectasia following laser in situ keratomileusis. J Cataract Refract Surg. 1999;25582- 586Article
McLeod  SDKisla  TACaro  NC  et al.  Iatrogenic keratoconus: corneal ectasia following laser in situ keratomileusis for myopia. Arch Ophthalmol. 2000;118282- 284
Seiler  TKoufala  KRichter  G Iatrogenic keratectasia after laser in situ keratomileusis. J Refract Surg. 1998;14312- 317
Seiler  TQuurke  AW Iatrogenic keratectasia after LASIK in a case of forme fruste keratoconus. J Cataract Refract Surg. 1998;241007- 1009Article
Koch  D The riddle of iatrogenic keratectasia. J Cataract Refract Surg. 1999;25453- 454Article
Seitz  BTorres  FLangenbucher  A  et al.  Posterior corneal curvature changes after myopic laser in situ keratomileusis. Ophthalmology. 2001;108666- 673Article