Abstract
To evaluate the clinical outcomes of intrastromal corneal ring segment (ICRS) implantation to correct ectasia in eyes with prior refractive surgery. Forty-one eyes of 25 patients (13 men, 12 women; mean age, 28.66 years) with ectasia after refractive surgery [photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK)] were included in a nonrandomized, retrospective, observational case series. Corneal tunnels were created by mechanical dissection in all eyes. Main outcome measures included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BCVA), refraction, keratometry, and computerized analysis of corneal topography. Patients were divided into two groups by the type of refractive surgery (Group A: PRK, Group B: LASIK). The mean preoperative manifest astigmatism decreased from -1.88 to -0.84 D in Group A (p=0.096) and -3.18 to -1.77 D in Group B (p=0.000). The mean keratometric astigmatism decreased from -2.58 to -1.66 D in Group A (p=0.010) and -4.80 to -2.78 D in Group B (p=0.000). The mean spherical equivalent decreased from -2.97 to -2.05 D in Group A (p=0.065) and -3.31 to -2.42 D in Group B (p=0.014). No significant between-group differences were noted on the comparison of preoperative and postoperative results. No intraoperative or postoperative complications were observed. ICRS implantation is a useful treatment option for ectasia following refractive surgery, and it has significantly reduced the refractive cylinder and increased best spectacle-corrected visual acuity.
Highlights
Keratoconus (KCN) is a noninflammatory ectatic condition in which the cornea assumes a conical shape because of weakness, thinning, and anterior protrusion of the corneal surface[1,2,3]
A similar clinical entity may be observed in some patients following a refractive procedure [laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK)] and is characterized by subsequent progressive corneal thinning and bulging, with topography similar to that of KCN
The intrastromal corneal ring segment (ICRS) segment was uneventfully implanted in all cases
Summary
Keratoconus (KCN) is a noninflammatory ectatic condition in which the cornea assumes a conical shape because of weakness, thinning, and anterior protrusion of the corneal surface[1,2,3]. A similar clinical entity may be observed in some patients following a refractive procedure [laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK)] and is characterized by subsequent progressive corneal thinning and bulging, with topography similar to that of KCN. The exact incidence of post-refractive surgery ectasia remains unknown. Several parameters such as high myopic corrections, thin corneas, and residual corneal bed thickness less than 250 mm represent the major risk factors for this condition[4,5,6,7]. Therapeutic treatment options include gas-permeable lenses, corneal collagen crosslinking, and deep lamellar or penetrating keratoplasty[8]
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