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To intraoperatively determine and compare the characteristics and predictability of LASIK flaps made by the WaveLight FS200 femtosecond laser (Alcon Laboratories Inc) and Hansatome (Bausch & Lomb) microkeratome using a hand-held spectral domain ophthalmic imaging system (Bioptigen Inc). Sixty eyes from 30 patients undergoing bilateral LASIK were prospectively evaluated. Patients were divided into two equal groups to undergo flap creation with either 100-microm femtosecond laser flaps (FS flap group) or 120-microm microkeratome flaps (MK flap group). Flap thickness was measured intraoperatively after creation of the flap but prior to lifting using the hand-held probe of the spectral domain imaging system. Geometry of the flap edge and smoothness of the stromal bed after lifting the flap was also evaluated in all cases. Mean difference between planned and achieved flap thickness in the paracentral region was 2.84 +/- 3.16 mm for the FS flap group and 11.33 +/- 10.27 mm for the MK flap group, whereas in the periphery, it was 5.72 +/- 3.26 mm in the FS flap group and 24.67 +/- 10.35 mm in the MK flap group. The differences between groups were statistically significant (P < 0.001, Kruskal-Wallis test). The edges of the flaps were vertical in the FS flap group and the stromal bed was smoother, whereas in the MK flap group, the edges were more sloping and the stromal bed more irregular. The WaveLight FS200 femtosecond laser is able to produce planar flaps with a high degree of predictability between the desired and achieved flap thickness. The ability to study the flap characteristics intraoperatively (when flap edema and stromal bed hydration changes have not yet occurred) with the hand-held probe of the Bioptigen imaging system ensures greater accuracy than measurements done postoperatively using other anterior segment optical coherence tomography prototypes. Source

Pahuja N.,Narayana Nethralaya Eye Hospital | Shetty R.,Narayana Nethralaya Eye Hospital | Subbiah P.,Narayana Nethralaya Eye Hospital | Nagaraja H.,Narayana Nethralaya Eye Hospital | And 2 more authors.
Cornea | Year: 2016

Purpose: To assess the repeatability of densitometry, a measure of corneal haze, in the control (group I), keratoconic (group II), and postcollagen cross-linking (CXL, group III) eyes as measured on Scheimpflug imaging. Methods: Densitometry values for 160 eyes of 160 patients (50 eyes of 50 patients in group I, 50 eyes of 50 patients in group II, and 60 eyes of 60 patients in group III) were obtained for the 0-to 2-mm, 2-to 6-mm, and 6-to 10-mm zones of the anterior (up to 120 mm), posterior (posterior 60 mm), and central (between the anterior and posterior) cornea. The repeatability of these values was assessed by within-subject standard deviation, coefficient of repeatability, and coefficient of variation. Results: Range of within-subject standard deviation and coefficient of variation in the control group (0.2%-0.5% and 2%-4%, respectively) was significantly better (less variable) than those in the keratoconus group (0.4%-0.6% and 3%-5%). The same parameters in the post-CXL group (0.8%-3.8% and 7%-15%) were significantly worse (more variable) than that in the other 2 groups. The repeatability measures of densitometry were significantly worse in the central 0-to 2-mm zone compared with the other 2 zones and for the anterior region compared with the central and posterior regions of cornea in all the 3 groups. Conclusions: Consequent to the low repeatability in post-CXL eyes, densitometry should be used with caution to gauge response to treatment and visual outcomes in treated keratoconus eyes. © 2016 Wolters Kluwer Health, Inc. All rights reserved. Source

Shetty R.,Narayana Nethralaya Eye Hospital | Nagaraja H.,Narayana Nethralaya Eye Hospital | Jayadev C.,Narayana Nethralaya Eye Hospital | Pahuja N.K.,Narayana Nethralaya Eye Hospital | And 2 more authors.
BioMed Research International | Year: 2014

Purpose. To evaluate the effectiveness and safety of accelerated corneal collagen cross-linking (ACXL) in patients below 14 years of age with progressive keratoconus. Materials and Methods. Thirty eyes of 18 patients with established progressive keratoconus underwent preoperative and postoperative visual acuity assessment, topography, and specular microscopy prior to ACXL and were followed up for 24 months. Results. Mean age of the patients was 12.7 years with ten males and eight females. There was an improvement in the mean postoperative uncorrected distant visual acuity (from 0.76 ± 0.26 to 0.61 ± 0.25; P = 0.005), mean corrected distant visual acuity (from 0.24 ± 0.19 to 0.12 ± 0.12; P < 0.001), mean spherical refraction (from - 3.04 DS ± 3.60 to - 2.38 DS ± 3.37; P = 0.28), mean cylinder (from - 3.63 DC ± 1.82 to - 2.80 DC ± 1.48; P = 0.008), and spherical equivalent (from - 4.70 D ± 3.86 to - 3.75 D ± 3.49; P = 0.15). Three eyes of two patients with vernal keratoconjunctivitis (VKC) showed progression. There were no intra- or postoperative complications. Conclusion. In pediatric patients ACXL is an effective and safe procedure for the management of keratoconus. Optimal management of VKC is important to arrest the progression of keratoconus. © 2014 Rohit Shetty et al. Source

Shetty R.,Narayana Nethralaya Eye Hospital | Nagaraja H.,Narayana Nethralaya Eye Hospital | Veluri H.,Narayana Nethralaya Eye Hospital | Shivanna Y.,Narayana Nethralaya Eye Hospital | And 3 more authors.
Indian Journal of Ophthalmology | Year: 2014

Aim: To study the safety and efficacy of sutureless femtosecond anterior lamellar keratoplasty (FALK) in patients with corneal stromal opacities. Materials and Methods: Eleven eyes of 11 consecutive patients with corneal stromal opacities involving < 250 μ due to various pathologies were included in the study. Preoperatively, all underwent anterior segment imaging with spectral domain optical coherence tomography (SD-OCT) (Bioptigen Inc., Durham, North Carolina, USA) to measure the depth of the stromal opacity. All patients underwent FALK, and bandage contact lens was placed for a period of 2 weeks. Postoperatively, uncorrected visual acuity, best corrected visual acuity (BCVA), and SD-OCT evaluation were performed. Results: All patients showed significant improvement in BCVA. The mean postoperative BCVA (in decimals) improved from 0.11 ± 0.06 preoperatively to 0.59 ± 0.08. There were no intraoperative or significant postoperative complications that were noticed. Conclusion: FALK is a safe and effective alternative to deep anterior lamellar keratoplasty or penetrating keratoplasty in the treatment of anterior stromal opacities. Source

Shetty R.,Narayana Nethralaya Eye Hospital | Pahuja N.K.,Narayana Nethralaya Eye Hospital | Nuijts R.M.M.A.,Maastricht University | Ajani A.,Narayana Nethralaya Eye Hospital | And 3 more authors.
American Journal of Ophthalmology | Year: 2015

Purpose To study the effect of different protocols of collagen cross-linking on visual, refractive, and tomographic parameters in patients with progressive keratoconus. Design Prospective randomized interventional study. Methods In this study, 138 eyes of 138 patients with progressive keratoconus underwent corneal collagen cross-linking (CXL). Following detailed preoperative examination, Group I underwent conventional cross-linking (36 patients, 3 mW/cm2 for 30 min); Group II (36 patients, 9 mW/cm2 for 10 min), Group III (33 patients, 18 mW/cm2 for 5 min), and Group IV (33 patients, 30 mW/cm2 for 3 min) underwent accelerated cross-linking. Changes in corrected distance visual acuity (CDVA), spherical equivalent (SE), flat keratometry, steep keratometry, thinnest pachymetry, specular microscopy, and demarcation line were studied at 6 and 12 months. Results Improvement in the mean CDVA and SE were statistically significant in all groups except Group IV (P =.15 at 6 months, P =.17 at 12 months), with Group III (P =.01 at 6 and 12 months) showing the best results. Flattening of steep and flat keratometry was significant in Groups I (P =.01) and II (P =.01) as compared to the other groups. There was no significant difference in the pachymetry or specular microscopy in any of the groups. Groups I and II demonstrated a good demarcation line when compared to other groups. Conclusion Conventional CXL (Group I) and accelerated CXL with irradiations of 9 mW/cm2 (Group II) and 18 mW/cm2 (Group III) showed better visual, refractive, and tomographic improvements at the end of 12 months. © 2015 Elsevier Inc. All rights reserved. Source

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