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A.H. Sandoval, R. Velasco, O. Baca, A. Babayan, D. Viggiano, A. Flores; Contrast Sensitivity After Intrastromal Corneal Ring Segments Implantation . Invest. Ophthalmol. Vis. Sci. 2006;47(13):584.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effects of intrastromal corneal ring segments implantation on contrast sensitivity (CS).
This prospective, comparative, experimental and longitudinal study included patients with keratoconus. All patients had clear central corneas and contact lens intolerance. Postoperative evaluations were programmed at 1 week, and 1, and 3 months after surgery. The preoperative evaluation included uncorrected visual acuity (UCVA) and best–corrected visual acuity (BCVA), spherical equivalent (SE), manifest and cyclopegic refraction, slit–lamp examination, applanation tonometry, keratometry, ophthalmoscopy and topography (Orbscan II). Additionally, far and near constrast sensitivity test were measured at 1.5, 3, 6, 12 ad 18 cycles per degree (c/g). Logarithmic values of CS at each spatial frequency were used for statistical analysis and normalized values were used for graphical representation. The mean follow–up was 6 months. Concerning quantitative data, the comparisons between pre and postoperative periods were performed using the Student t for paired data.
Far CS decreased 1 week postoperatively only at the low spatial frequencies of 1.5 and 3 c/d but improved for 1 and 3 months in all spatial frequencies, although the changes were not significant (p>0.05). One week after surgery, near CS decreased at the intermediate and high frequencies, starting from the first month, there was slow recovery. By the 3–month visit, all eyes showed an improvement of SC near, although the changes were not significant (p>0.05). All of the patients gained one or more lines of vision. The mean UCVA significantly improved from 0.13 to 0.40 (p<0.001). The mean BCVA also improved from 0.28 to 0.57 (p<0.001). The preoperative SE ranged from –1.62 diopters (D) to –20.12 Diopters (D) (mean –7.4 D). At 3 months postoperatively the spherical equivalent ranged from 0.5 diopters (D) to –17.62 Diopters (D) (mean –6.2 D) (p=0.107)
Implantation of intrastromal corneal ring segments improved the contrast sensitivity and the quality of vision in eyes with keratoconus.
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