Topography-guided (TG) LASIK vs small incision lenticule extraction (SMILE): Posterior and anterior corneal power outcomes [Meeting Abstract]
Purpose: Evaluate safety, efficacy and changes of anterior and posterior corneal power of topo-guided LASIK vs. SMILE in contralateral eyes, in myopic laser refractive surgery. Methods: In 22 myopic patients: 22 eyes had TG LASIK, and the contralateral eye had SMILE. Preoperative and postoperative evaluation of: spherical equivalent stability (SE). The eyes were divided in two groups of spherical equivalent (SE). The first group contains eyes with SE between -10 and -5.01 (High Zone) while the second group contains eyes with SE from -5 to 0. All data for corneal power were extracted from Optovue OCT device. Results: In the case of high zone, the anterior corneal power for SMILE technique was preoperatively 49.96+/-167 D and 43.23+/-1.99 D postoperatively. On the other hand, when EX500 method was used, preoperatively the corneal power was 50.20+/-1.58 D and 42.57+/-1.84 D postoperatively. The corresponding results for mild SE zone in the case of SMILE technique were 50.47+/-1.77 D preoperatively and 46.54+/-1.71 D. For the EX500 technique the corneal power pre-op and post-op was 49.35+/-2.43 D and 46.50+/-2.68 D respectively. Concerning posterior corneal power when SMILE method was used, in case of high SE zone the posterior corneal power changed from -6.16+/-0.23 D pre-op to 6.18+/-0.28 D postop. When EX500 method was used the corresponding results were 6.21+/-0.22 D and -6.24+/-0.22 D. Finally in the case of mild SE zone the posterior corneal power increased from -6.23+/-167 to -6.26+/-0.26 D when SMILE method was applied, while for the eyes that surged with EX500 technique the posterior corneal power was -6.15+/-0.37 D pre-op and -6.16+/-0.38 D post-op. Conclusions: Anterior and posterior corneal power was calculated after SMILE and EX500 refractive operations. The results presented, clearly showed that after EX500 operation, anterior corneal power is lower in comparison to SMILE operation in high SE zone. In mild SE zone the anterior corneal power is almost the same for the both methods. On the other hand the posterior corneal power remains unchanged, regardless the SE zone and the operation method
Topography-Guided LASIK Versus Small Incision Lenticule Extraction (SMILE) for Myopia and Myopic Astigmatism: A Randomized, Prospective, Contralateral Eye Study
PURPOSE: To compare safety and efficacy of topography-guided LASIK and contralateral eye SMILE for myopia and myopic astigmatism correction. METHODS: This prospective, randomized contralateral eye study included 44 eyes of 22 patients with bilateral myopia or myopic astigmatism. Treated eyes were divided into two groups: 22 eyes were treated with topography-guided LASIK and the fellow eye of each patient was treated with SMILE. The following parameters were evaluated preoperatively and up to 3 months postoperatively: uncorrected distance vision acuity (UDVA), corrected distance vision acuity (CDVA), refractive error, corneal keratometry, contrast sensitivity, and Objective Scatter Index. RESULTS: At 3 months, 86.4% of the LASIK group and 68.2% of the SMILE group had UDVA of 20/20 (P < .002) and 59.1% and 31.8%, respectively, had UDVA of 20/16 (P < .002). Spherical equivalent refraction (+/-0.50 D) was 95.5% for the LASIK group and 77.3% for the SMILE group (P < .002). Residual refraction cylinder (= 0.25 D) was 81.8% for the LASIK group and 50% for the SMILE group (P < .001). Contrast sensitivity (6 cycles/degree) was 7.2 +/- 1.01 in the LASIK group and 6.20 +/- 1.52 in the SMILE group. Objective Scatter Index measurements at 3 months were 1.35 in the LASIK group and 1.42 in the SMILE group. CONCLUSIONS: Topography-guided LASIK was superior in all visual performance parameters studied, both subjective and objective. The main difference between the two techniques likely derives from the eye tracking, cyclorotation compensation, and active centration control in the LASIK technology studied in contrast to the current technology available with SMILE-like procedures. This difference appears to affect refractive and visual aberration performance outcomes. [J Refract Surg. 2017;33(5):306-312.].
December consultation #2
Refractive results comparison between myopic small-incision lenticule extraction and LASIK [Meeting Abstract]
Purpose: The purpose of this study was to comparative investigate two myopic correction femtosecond laser techniques: femtosecond-assisted LASIK was compared to an all femto-second laser Small Incision refractive Lenticule Extraction (SMILE). Six-month refractive outcomes were comparatively evaluated. Methods: This is a single-center, retrospective analysis of 100 consecutive myopic patients. Group-A was treated with the SMILE (n=48 eyes), while the other eye (group-B) with LASIK (n=52 eyes). The LASIK procedure employed the Alcon Refractive surgery platform (Alcon Surgical, Ft. Worth, TX) comprised of the FS200 femtosecond and the EX500 excimer laser. The SMILE procedure employed the 500 kHz VisuMax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany). All operations were performed by the same surgeon (AJK). Results: LASIK SEQ corrected: -5.12+/-2.74 D(range -1.50 to -12.00). 6-month results: 82% within +/- 0.25D, 87% within +/- 0.50D; 91 % had 20/20 UDVA or better; 54% no change in Snellen lines, 46% gained 1 or more; predictability r^2 = 0.999. SMILE SEQ corrected: -4.63+/-1.90 D (range -2.50 to -9.50). 6-month results: 84 % within +/- 0.25D, 95% within +/- 0.50D; 88% had 20/20 UDVA or better; 45% no change in Snellen lines, 55% gained 1 or more; predictability r^2 = 0.972. Conclusions: FS-assisted LASIK and SMILE appear to have similar refractive results up to 6 months
Contralateral investigation of postoperative refractive surgery inflammation: Small-incision Lenticule Extraction vs LASIK [Meeting Abstract]
Purpose: The purpose of this study was to comparative investigate potential impact of inflammation following myopic correction. The established current gold standard of femtosecond-assisted LASIK was compared to an all femto-second laser Small Incision refractive Lenticule Extraction (SMILE). No study has investigated the potential differences between SMILE and LASIK from the stand-point of postoperative inflammation. Methods: This is a contralateral, perspective stud employing 10 consecutive myopic patients, in which one eye (group-A) was treated with the SMILE, while the other eye (group-B) with LASIK. The LASIK procedure employed the Alcon Refractive surgery platform (Alcon Surgical, Ft. Worth, TX) comprised of the FS200 femtosecond and the EX500 excimer laser. The SMILE procedure employed the 500 kHz VisuMax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany). InflammaDry (Rapid Pathogen Screening, Inc., Sarasota, FL) is an in-office test that detects matrix metalloproteinase MMP-9, an inflammatory marker that is consistently elevated in the tears of patients with dry eye disease. Using direct sampling microfiltration technology, InflammaDry identifies elevated levels of MMP-9 protein in tear fluid samples taken from the palpebral conjunctiva. Levels of MMP-9 were tested 1-month, 3-months and 6-months postoperatively, facilitated with the use of InflammaDry solution. Inclusion criteria: 18 years of age or older. Exclusion Criteria: Allergy to cornstarch or Darcon, Allergy to topical anesthetic or fluorescein dye. Results: MMP-9 levels in group-A (LASIK) were 65+/-15 ng/ml, 55+/-12 ng/ml, 45+/-9 ng/ml at 1-, 3-, and 6-months, respectively. MMP-9 levels in group-B (SMILE) were 45+/-13 ng/ml, 42+/-12 ng/ml, 37+/-8 ng/ml at 1-, 3-, and 6-months, respectively. All groups displayed statistically significant differences at the perspective follow-up periods examined. Conclusions: Potential differences between LASIK and SMILE include increased inflammation levels postoperatively up to 6 months
Small incision lenticule extraction (SMILE) vs LASIK: An ex vivo biomechanical evaluation of low and high myopic corrections [Meeting Abstract]
Purpose : The small-incision lenticule extraction (SMILE) procedure and laser in situ keratomileusis (LASIK) are both safe, effective, and predictable surgical techniques for the correction of myopia. SMILE presents an alternative to LASIK, which currently may be considered the most established form of laser vision correction. The purpose of this study is to evaluate corneal biomechanical changes associated with low and high myopic correction performed with small incision lenticule extraction (SMILE, employing the Visumax laser, Carl Zeiss Meditec, Jena Germany) compared to Femtosecond-laser assisted LASIK (FS200 & EX500 lasers, Alcon Surgical, Ft. Worth, TX) Methods : Thirty human donor corneas were subjected to myopic SMILE or LASIK. These corneas were randomly allocated to one of four investigative groups (n=5 each), subjected to the following treatments: group-A -3.00 diopters (D) SMILE; group-B -8.00D SMILE; group-C -3.00D LASIK; group-D -8.00D LASIK. Additionally, two control groups (n=5 each) were formed, one for each procedure: group-E SMILE and group-F LASIK. The corneas in these control groups were subjected to the corresponding femtosecond-laser lamellar cuts but not to tissue removal. Biomechanical evaluation of tensile strength was conducted by biaxial force application. Primary outcome measures were stress at 10% and 15% strain, and Young's modulus at 10% and 15% strain. Results : In SMILE, the average relative difference (DELTA) of the four metrics evaluated was -35.6% between the -3.00D correction and control and -50.2% between the -8.00D correction and control. In LASIK, average DELTA was -21.2% between the -3.00D correction and control, and -50.4% between the -8.00D correction and control. When evaluating the same degree of myopic correction, SMILE, compared to LASIK, appears to result in greater biomechanical reduction for the -3.00D correction (-25.9%) while the difference at -8.00D correction is not statistically significant. Conclusions : Biomechanical tensile strength is reduced with increasing amounts of myopia corrected in both procedures. LASIK results in less strength reduction in smaller myopes while, in higher myopes, SMILE and LASIK appear to result in similar corneal tensile strength reduction
Nanosecond laser-assisted cataract surgery: Endothelial cell study
PURPOSE: To evaluate corneal endothelial cell density (ECD) and morphology after cataract surgery using coaxial ultrasound (US) phacoemulsification or a recently introduced coaxial nanosecond laser technique. SETTING: Department of Ophthalmology, Medical University of Sofia, Sofia, Bulgaria. DESIGN: Prospective cohort study. METHODS: Coaxial US phacoemulsification was performed in 1 eye (US group) and coaxial nanosecond laser-assisted cataract surgery in the contralateral eye (laser group) of the same patient. Nuclear sclerosis was graded from nuclear opalescence (NO) 3, nuclear color (NC) 3 to NO4, NC4 using the Lens Opacities Classification System III. The central ECD, coefficient of variation (CoV) in cell size (objective measure of polymegethism), and percentage of hexagonal cells (an index of pleomorphism) were evaluated. RESULTS: Eighty-two eyes (41 patients) had uneventful surgery. The mean ECD was 2517 cells/mm(2) +/- 137 (SD) preoperatively and 2287 +/- 155 cells/mm(2) at 2 years in the US group and 2521 +/- 233 cells/mm(2) and 2420 +/- 292 cells/mm(2), respectively, in the laser group (both P < .001). The mean CoV was 0.27 +/- 2.4 preoperatively and 0.30 +/- 2.4 at 2 years in the US group and 0.27 +/- 2.8 and 0.27 +/- 2.0, respectively, in the laser group (both P < .001). The mean percentage of hexagonal cells was 42.3% +/- 3.6% preoperatively and 37.74% +/- 3.54% at 2 years in the US group and 42.8% +/- 3.2% and 43.00% +/- 2.68%, respectively, in the laser group (both P < .001). CONCLUSION: Nanosecond laser phacoemulsification had advantages over US phacoemulsification in terms of endothelial cell structure preservation. FINANCIAL DISCLOSURES: Dr. Kanellopoulos is consultant to Alcon Surgical, Inc., Allergan, Inc., Avedro, Inc., Keramed, Inc., Optovue, Inc., i-Optics Corp., and Carl Zeiss Meditec AG. Neither of the other authors has a financial or proprietary interest in any material or method mentioned.
Cross-Linking Biomechanical Effect in Human Corneas by Same Energy, Different UV-A Fluence: An Enzymatic Digestion Comparative Evaluation
PURPOSE: To evaluate ex vivo the possible difference in corneal cross-linking (CXL) biomechanical effect of different ultraviolet-A (UV-A) irradiances. METHODS: The study involved 25 human donor corneas, randomly allocated to 5 groups (n = 5 each). CXL was applied with UV-A irradiances of 3, 9, 18, 30, and 45 mW/cm, maintaining equal cumulative energy dose of 5.4 J/cm. UV-A was delivered on half of the cornea. The nonirradiated halves served as controls. Specimens were subjected to collagenase-A enzymatic digestion. The time to complete dissolution in each specimen was recorded. RESULTS: Time to dissolution in group-A (3 mW/cm for 30 minutes) was 321 +/- 13.4 minutes (range: 300-330) compared with 171 +/- 8.2 (range: 165-180) for their control. In group-B (9 mW/cm for 10 minutes), it was 282 +/- 19.6 minutes (range: 270-315) compared with 177 +/- 6.7 (165-180) for their control. In group-C (18 mW/cm for 5 minutes), it was 267 +/- 19.6 minutes (range: 240-285) compared with 177 +/- 7.7 (range: 165-180) for their control. In group-D (30 mW/cm for 3 minutes), it was 252 +/- 12.5 minutes (range: 240-270) compared with 180 +/- 10.6 minutes (range: 165-195) for their control. In group-E (45 mW/cm for 2 minutes), it was 204 +/- 17.1 minutes (range: 180-225) compared with 186 +/- 8.2 minutes (range: 180-195) for their control. CONCLUSIONS: The data in this ex vivo human corneal study indicate that the biomechanical effect of CXL studied by resistance to enzymatic digestion in human corneas is comparable between irradiances of 9, 18 and 30 mW/cm and seems to be reduced at a fluence of 45 mW/cm.
In pursuit of objective dry eye screening clinical techniques
Dry eye is a multifactorial, progressive, and chronic disease of the tears and ocular surface. The disease is multi-factorial and has intermittent symptoms. Discomfort, visual disturbance, tear film instability with potential damage to the ocular surface, and increased tear film osmolarity are known associates. Dry eye is a common clinical problem for eye-care providers worldwide and there is a large number of clinical investigative techniques for the evaluation of dry eye. Despite this, however, there is no globally accepted guideline for dry eye diagnosis and none of the available tests may hold the title of the 'gold standard'. The majority of the techniques involved in the diagnosis of the disease, particularly for its early stages, has a large degree of subjectivity. The purpose of this article is to review existing dry eye investigative techniques and to present a new objective dry eye screening technique based on optical coherence tomography.
Higher incidence of steroid-induced ocular hypertension in keratoconus
BACKGROUND: To compare intraocular pressure (IOP) changes following topical dexamethasone administration for 1 month in keratoconic versus normal eyes. METHODS: This is a retrospective, single-center, non-randomized case series evaluation of 350 eyes. Two groups were formed: normal/control Group A (nA =73), eyes that underwent excimer laser photorefractive keratectomy; and keratoconic (KCN) Group B (nB =277), eyes that were subjected to partial laser photorefractive keratectomy combined with collagen cross-linking (The Athens Protocol). All eyes received the same post-operative regimen of topical dexamethasone 0.1 % for at least 1 month. Goldmann applanation tonometry IOP readings and central corneal thickness (CCT) measurements were monitored. Cases with induced ocular hypertension (OHT, defined as post-operative IOP higher than 21 mmHg), were identified and correlated to refractive procedure, gender, and corneal thickness. RESULTS: At 4 weeks postoperatively, OHT was noted on 27.4 % (20 /73 eyes) in Group A, and 43.7 % (121 /277 eyes) in KCN Group B, (p <0.01). Six months post-operatively (following 5-months of discontinuing topical dexamethasone treatment and commencing treatment of IOP-lowering medications), OHT rate was 1.8 % in Group A and 3.9 % in the KCN Group B. CONCLUSION: This study demonstrates a potentially significant pre-disposition of keratoconic eyes to the development of steroid-induced OHT.