Corneal Thickness and Topography Indices after Collagen Cross-linking for Keratoconus: 18 Months Follow-up and Literature Review

Objective: To evaluate the changes in corneal topography indices and corneal thickness after cross-linking treatment for keratoconus. Study Design: Retrospective Observational Study Patients and Methods: The data of patients who underwent corneal collagen cross-linking treatment for keratoconus were retrieved. Central corneal thickness (CCT), maximum and mean keratometry (Kmax, Kmean) values and topography indices: index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), minimum radius of curvature (Rmin), index of height asymmetry (IHA), and index of height decentration (IHD) were obtained from Pentacam and Wavelight-Allegretto Wave Topolyzer outputs. Follow-up was 18 months. Results: The study comprised of 15 eyes of 10 patients with keratoconus. Central corneal thickness had decreased significantly 1 month after the procedure (p=0.003) but there were no statistically significant changes between the baseline values and last visits (p>0.05). Kmax and Kmean values were not statistically different from the preoperative values and at the last visits (p>0.05). Almost all of the corneal topography indices improved significantly after postoperative 6th month (p<0.05). Conclusion: There were improvements in topography indices during 18-month follow-up period, suggesting that the cornea becomes more optically regular and symmetrical after cross-linking

Corneal thickness measurements by ultrasonic pachymetry and scheimpflug system

Amaç: Scheimpflug görüntüleme (Pentacam, Oculus, Germany) ve ultrasonik pakimetri (Tomey pachymeter, SP-3000, USA) ile kornea kalınlığı ölçümlerini karşılaştırmak. Gereç ve Yöntem: Refraktif cerrahi için başvurmuş, korneası sağlıklı 200 hastanın 400 gözü retrospektif olarak incelendi. Bu 400 gözün Pentacam ile ultrasonik pakimetri değerleri analiz edildi. Bulgular: Ortalama merkezi kornea kalınlığı Pentacam ile 545,00±1,49 (470-623) ? ve ultrasonik pakimetri ile 546,74±1,58 (467-640) ? idi (p=0,002). Bu iki ölçüm yöntemi arasında pozitif korelasyon vardı (r=0,939, p<0,001). Üç mm parasantral kornea kalınlığı superiorda 656,53±1,91 (565-765) ?, nazalde 627,87±1,86 (543-867) ?, inferiorda 616,62±1,65 (529-716) ? ve temporalde 607,92±1,71 (513-708) ? (p<0,001) idi. Ortalama kornea kalınlığı superiorda en fazla ve temporalde en ince idi (p<0,001). Üç yüz yetmiş sekiz gözde (%94,5) superior kornea en kalın ve 272 gözde (%68) temporal kornea en ince idi (p<0,001). Merkezi ve inferior kornea kalınlıkları arasındaki fark 71,63±0,77 ? (p<0,001, %95 güvenilirlik aralığı: -73,14 ile -70,11 arası) idi. Sonuç: Korneanın ektatik hastalıklarında, merkezi kornea ile inferior kornea arasındaki rölativite değiştiğinden; rutin klinik pratikte sadece merkezi değil, parasantral kornea kalınlığı da değerlendirilmelidir. Sağ ve sol göz arasında kornea kalınlığı asimetrisi de kornea hastalığı şüphesi açısından klinisyeni uyarmalıdır.Aim: To compare corneal thickness mesurements by Scheimpflug imaging (Pentacam, Oculus, Germany) and ultrasonic pachymetry (Tomey pachymeter, SP-3000, USA). Material and Method: The records of 200 patients with healthy corneas who had applied for refractive surgery were evaluated retrospectively. Pentacam and ultrasonic pachymetry values of these 400 eyes were analyzed. Results: The mean central corneal thickness was 545.00&plusmn;1.49 (470-623) &amp;#956; by Pentacam and 546.74&plusmn;1.58 (467-640) &amp;#956; by ultrasonic pachymeter (p=0.002). There was a positive correlation between these two measurement methods (r=0.939, p&lt;0.001). By Pentacam, 3 mm paracentral corneal thickness was 656.53&plusmn;1.91 (565-765) &amp;#956; superiorly, 627.87&plusmn;1.86 (543-867) &amp;#956; nasally, 616.62&plusmn;1.65 (529-716) &amp;#956; inferiorly and 607.92&plusmn;1.71 (513-708) &amp;#956; temporally (p&lt;0.001). The mean corneal thickness was highest at the superior and thinnest at the temporal side (p&lt;0.001). In 378 eyes (94.5%) superior cornea was the thickest and in 272 eyes (68%) the temporal cornea was the thinnest (p&lt;0.001). The mean difference between corneal thickness measurements at the center and inferiorly was 71.63&plusmn;0.77 &amp;#956; (p&lt;0.001, 95% confidence interval: from -73.14 to -70.11). Conclusion: Not only central but also paracentral corneal thickness should be evaluated routinely in clinical practice since the relativity of corneal thickness centrally to inferiorly is altered in ectatic diseases of the cornea. The corneal thickness asymmetry between fellow eyes should alert the physician for the suspicion of corneal disease

Comparison of visual acuity, refractive results and complications of femtosecond laser with mechanical microkeratome in LASIK

AIM: To compare the outcomes of laser in situ keratomileusis (LASIK) performed with a femtosecond laser (Femtec, Technolas Perfect Vision GmbH, Germany) versus a mechanical microkeratome (Hansatome, Bausch and Lomb, USA) for the correction of myopia and astigmatism. METHODS: In this retrospective study, patients who had undergone LASIK using the 80 -kHz Femtec femtosecond laser were compared to age- and refraction-matched patients in whom the Hansatome microkeratome was used. Refractive and visual results 1 month and 3 months postoperatively, and complication rates were compared between the two groups. RESULTS: A total of 280 eyes were analyzed (140 in each group). At 3 months postoperatively in the Femtec vs Hansatome group, spherical equivalent refraction was within +/- 1.00D of emmetropia in 140 vs 138 eyes (P= 0.498), the cylinder was within +/- 0.50D in 137 vs 139 eyes (P=0.622), and the UDVA was 20/20 or better in 136 vs 137 eyes, (P =0.724), respectively. There was no statistically significant difference in the complication rates between the two groups (P=0.099). CONCLUSION: LASIK performed both with Femtec femtosecond laser and Hansatome microkeratome achieved satisfactory refractive and visual results at 3 months postoperatively, without significant differences in efficacy, safety, and complication rates between the two procedures

Treatment of mixed astigmatism: early clinical outcomes withWaveLight and Technolas excimer lasers

Background/aim: We aimed to compare the results of WaveLight Allegretto Wave Eye-Q 400 Hz and Technolas 217z100 excimer lasers in the treatment of mixed astigmatism. Materials and methods: Forty-nine patients who underwent laser in situ keratomileusis for mixed astigmatism were included in this retrospective study. Twenty-eight eyes of 21 patients were treated with WaveLight and 46 eyes of 28 patients were treated with the Technolas excimer laser. The patients' visual acuities and refractive values were evaluated on postoperative day 1 and at 1 and 3 months. Results: In the WaveLight and Technolas groups, cylindrical refractive errors at month 3 were -0.92 +/- 0.28 D and -0.88 +/- 0.46 D, respectively. Spherical equivalent values for the groups at month 3 were -0.38 perpendicular to 0.73 D and -0.33 perpendicular to 0.20 D, respectively. There was no significant difference in postoperative uncorrected distance visual acuity at month 3 between the two groups (P = 0.671). At postoperative month 3, 70% of patients treated with WaveLight and 100% of patients treated with Technolas had an uncorrected distance visual acuity of 20/25 or better (P = 0.211). Conclusion: There were no significant differences in refraction and visual acuity between the WaveLight and Technolas groups during a 3-month follow-up period after laser in situ keratomileusis for mixed astigmatism

Treatment of mixed astigmatism: early clinical outcomes with WaveLight and Technolas excimer lasers

Background/aim: We aimed to compare the results of WaveLight Allegretto Wave Eye-Q 400 Hz and Technolas 217z100 excimer lasers in the treatment of mixed astigmatism. Materials and methods: Forty-nine patients who underwent laser in situ keratomileusis for mixed astigmatism were included in this retrospective study. Twenty-eight eyes of 21 patients were treated with WaveLight and 46 eyes of 28 patients were treated with the Technolas excimer laser. The patients' visual acuities and refractive values were evaluated on postoperative day 1 and at 1 and 3 months. Results: In the WaveLight and Technolas groups, cylindrical refractive errors at month 3 were -0.92 +/- 0.28 D and -0.88 +/- 0.46 D, respectively. Spherical equivalent values for the groups at month 3 were -0.38 perpendicular to 0.73 D and -0.33 perpendicular to 0.20 D, respectively. There was no significant difference in postoperative uncorrected distance visual acuity at month 3 between the two groups (P = 0.671). At postoperative month 3, 70% of patients treated with WaveLight and 100% of patients treated with Technolas had an uncorrected distance visual acuity of 20/25 or better (P = 0.211). Conclusion: There were no significant differences in refraction and visual acuity between the WaveLight and Technolas groups during a 3-month follow-up period after laser in situ keratomileusis for mixed astigmatism