1. Comparison of single-segment and double-segment Intacs® insertion with femtosecond laser for keratoconus Tiep KHUC, Marc DOAT, Jean-Louis BOURGES, Nicolas ALFONSI, Jean-Marc LEGEAIS, Gilles RENARD Hôtel-Dieu Hospital, Paris, France Authors have no financial interest

2. Purpose To evaluate the efficacy of single-segment Intacs® using the femtosecond laser (IntraLase®, AMO) for insertion and compare with double-segment Intacs® in subjects with keratoconus

3. Methods (1/2) Setting: Hôtel-Dieu, Paris, France Prospective study 66 eyes of 59 patients classified into two groups - single-segment group: 38 eyes, 35 patients - double-segment group: 28 eyes, 26 patients Both groups matched by t test

4. Methods (2/2) Implantation procedure Femtosecond IntraLase ® FS 2 laser (60 kHz) (IntraLase Corp.) Parameters - dissection’s depth in the cornea was 80% of the central pachymetry (300 – 400 µ) - channel dissection size: 6.6 x 7.6 mm Main outcome measure: improvement of visual acuity, refractive error, K values Follow-up: 6 months Single or double-segment Intacs® implanted according to keratoconus asymetry and spherical equivalent (SE)

5. Global results VariablePreoperativePostoperative UCVA (logMAR)1.13±0.46 (0.5/10)0.57±0.45 (3/10) BSCVA (logMAR)0.54±0.33 (3/10)0.34±0.30 (5/10) Sphere (D)-3.37±4.05-1.62±2.76 Cylinder (D)-3.90±2.09-2.55±1.80 SE (D)-5.41±4.35-2.70±2.99 Steep K (D)57.4±7.354.0±6.9 Flat K (D)46.4±7.143.4±5.0 Average K (D)51.9±6.548.7±5.5 p < 0.05 for each variable.

6. Single-segment results VariablePreoperativePostoperative UCVA (logMAR)1.01±0.49 (1/10)0.40±0.34 (4/10) BSCVA (logMAR)0.45±0.31 (4/10)0.24±0.22 (6/10) Sphere (D)-2.53±3.93-1.34±2.56 Cylinder (D)-4.14±2.16-1.93±2.47 SE (D)-4.59±4.18-2.30±2.80 Steep K (D)56.1±6.852.7±6.0 Flat K (D)43.7±4.342.6±3.5 Average K (D)49.9±4.847.7±4.2 p < 0.05 for each variable. Improvement of UCVA for 34 eyes (89%).

7. Double-segment results VariablePreoperativePostoperative UCVA (logMAR)1.32±0.32 (0.5/10)0.82±0.48 (1.6/10) BSCVA (logMAR)0.69±0.32 (2/10)0.49±0.34 (3/10) Sphere (D)-4.95±3.92-2.25±3.16 Cylinder (D)-3.44±1.92-3.96±1.70 SE (D)-7.13±4.31-3.49±3.33 Steep K (D)59.6±7.856.4±7.8 Flat K (D)50.4±8.644.8±6.9 Average K (D)55.0±7.850.6±7.0 p < 0.05 for each variable, except cylinder (p=0.18). Improvement of UCVA for 21 eyes (75%).

8. Comparison double vs single- segment Only 1 eye experienced loss of BSCVA in the single-segment group, versus 5 eyes in the double-segment group.

9. Complications No peroperative complication 8 Intacs® (7.6%) were removed from 5 eyes because of partial extrusion

10. Discussion (1/2) Safe and efficient; improvement of UCVA+++ Trend towards improved outcomes with single- segment Intacs® (more important reshaping of the cornea) Results consistent with existent data (Sharma, 2005) Cases of loss of vision may be attributed to an induced irregular astigmatism

11. Discussion (2/2) Double- segment (preop/postop/ differential) Single- segment (preop/postop/ differential) Superior and inferior flattening Superior steepening Inferior flattening

12. Conclusion Intacs® implantation using IntraLase® FS 2 was safe and effective for treating keratoconus Better results were achieved with single-segment Intacs® Colin J, Cochener B, Savary G, Malet F, Holmes-Higgin D. INTACS inserts for treating keratoconus: one-year results. Ophthalmology 2001;108:1409-1414. Siganos CS, Kymionis GD, Kartakis N, Theodorakis MA, Astyrakakis N, Pallikaris IG. Management of keratoconus with Intacs. Am J Ophthalmol 2003;135:64-70. Alio JL, Artola A, Hassanein A, Haroun H, Galal A. One or 2 Intacs segments for the correction of keratoconus. J Cataract Refract Surg 2005;31:943-953. Sharma M, Boxer Wachler BS. Comparison of single-segment and double-segment Intacs for keratoconus and post-LASIK ectasia. Am J Ophthalmol 2006;141:891-895. Ertan A, Kamburoglu G. Intacs implantation using a femtosecond laser for management of keratoconus: Comparison of 306 cases in different stages. J Cataract Refract Surg 2008;34:1521-1526.