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A.P. Schwartz, F. Esmail, H.N. Naikoo, A. Babayan, B. Tinio, P.A. Asbell; Intrastromal Corneal Rings for Myopia: A Ten–Year Follow–Up on Visual Outcomes . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4351.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the safety, efficacy and stability of intrastromal corneal rings (ICRs) 10 years after placement for myopia. Methods:Ten eyes with myopia treated with the placement of ICRs (360 degree PMMA ring placed in the peripheral cornea) were evaluated at 10–year follow–up for the following: 1) uncorrected visual acuity (UCVA), 2) best spectacle–corrected visual acuity (BSCVA), 3) manifest refraction spherical equivalent (MRSE), 4) induced manifest refraction cylinder (IMRC), and 5) self–reported symptoms. In addition, all patients had wavefront analysis, topography, pachymetry, slit lamp examination, keratometry and Schirmer testing. Ten year data were compared to 1–year postoperative results to assess visual stability and safety of implants over time. Results:Data showed that UCVA was 20/30 or better in 80% of eyes and 20/60 or better in 90% of eyes at 1–year follow–up, which is similar to the 60% and 90%, respectively, 10 years after ring placement. One–year follow–up MRSE ranged from –3.37 diopters to –.12 diopters with a mean of –1.33 diopters. Ten–year MRSE ranged from –2.87 diopters to +1.50 diopters with a mean of –0.85 diopters. This indicated no statistically significant difference in MRSE (F(1,8)=1.57, p=ns) indicating stability from 1–year to 10–year follow–up. Induced manifest cylinder at 10 years ranged from reduction of as much as .75 diopters of astigmatism to induction of 1.00 diopter of astigmatism in one case with 70% of patients experiencing induction of 0.25 diopters of cylinder or less. Mean central pachymetry at 1–year was 540 microns and at 10–year was 565 microns. This was not a statistically significant difference (F(1,7)=2.70, p=ns). While patients remained largely satisfied at 10 years, 50% reported mild blurring of vision and 60% reported mild difficulty with night vision. Slit lamp examinations showed stable ring position and clear corneas in all eyes without significant structural change. Conclusions: Intrastromal corneal rings are a safe, effective and stable method of correcting mild to moderate myopia and most patients continue to be satisfied with the results after ten years. Refraction and corneal examinations show stability of effect 10 years after ICR placement and there was no evidence of any safety issues or corneal instability 10 years post operatively. ICR and Intacts offer a non–laser and reversible alternative for correcting mild to moderate myopia without removal of tissue and without manipulation of the central cornea.
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