ISCRS in keratoconus

Purpose: To evaluate refractive effects of ISCR implantation in keratoconus patients. Methods: The 1583 keratoconic eyes of 921 patients keratoconus (II-III st) were treated with ISCR implantation with one or two segments according the special nomograms. Pre and post operative examination included Snellen uncorrected distance visual acuity (UDVA) and CDVA, manifest refraction, slitlamp biomicroscopy, fundus evaluation, ultrasound pachymetry, and corneal topography and aberrometry Orbscan system. Results: Pre Op: UCVA – 0.12 + 0.07; BCVA – 0.3 + 0.2; K-readers: 53.1 + 3.7 (steep meridian), 46.8 + 3.7 (flat meridian); PBFS – 54.75 + 1.9; SE – 7.2 + 3.5; astigmatism 6.1 + 1.5. Post Op: UCVA – 0.7 + 0.2; BCVA – 0.7 + 0.2; K-readers: 45.9 + 3.7 (steep meridian), 42.8 + 2.7 (flat meridian); PBFS – 51.0 + 2.1; SE – 2.0 + 1.5; astigmatism 2.5 + 0.7. Conclusion: ISCS implantation improves all main parameters of corneal topography; it flattens central optical zone, which results in increase of UCVA and remained stable over the follow-up period. The reduction in segment diameter seems to be of great importance to better and effective control of astigmatism. However, if the segments are nearer from the pupil margins, visual quality can be adversely affected by scattered rays of light reaching the retina inducing blur and glares. Therefore, a compromise between ring effect and visual quality should be found. Having 4 arclength options (90, 120, 160 and 210 degrees) makes ISCRs to be more flexible in surgical planning to achieve the better refractive outcomes