Femtosecond Laser –Assisted Stromal Lenticule Addition Keratoplasty for the Treatment of Advanced Keratoconus: A Preliminary Study
Despite recent advancements in keratoconus management with the introduction of corneal cross-linking (CXL) procedures, the surgical approach remains the only solution able to improve visual acuity when spectacles or contact lenses do not permit patients to achieve a useful visual function.1 –4 It has been reported that 15% to 28% of patients with keratoconus may require surgical intervention that includes penetrating or deep anterior lamellar keratoplasty.5,6 Intracorneal ring segment implantation in selected cases has been gaining acceptance as an alternative to corneal transplantation, (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Leonardo Mastropasqua, MD Source Type: research
Femtosecond Laser –Assisted LASIK With and Without the Adjuvant Use of Mitomycin C to Correct Hyperopia
LASIK has been shown to be a safe, effective, and predictable procedure to correct different degrees of myopia, hyperopia, and astigmatism.1,2 However, when compared with myopic corrections, predictability for comparable hyperopic refractive errors is much poorer.3 Thus, published studies indicate a good predictability for low to moderate hyperopic corrections,2 –5 up to +4.00 diopters (D) in most series, but less satisfactory results are reported in the correction of higher degrees of hyperopia.6 Although femtosecond laser –assisted LASIK (FS-LASIK) seems to achieve better refractive outcomes (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Montserrat Garcia-Gonzalez, MD, PhD Source Type: research
Evaluation of Femtosecond Laser Versus Manual Clear Corneal Incisions in Cataract Surgery Using Spectral-Domain Optical Coherence Tomography
The architecture of clear corneal incisions (CCIs) plays an important role in the outcome of phacoemulsification. Improper CCI construction can lead to a variety of complications, including Descemet's membrane detachments, wound leaks, and excessive surgically induced astigmatism. A previous study demonstrated that it was hard to predictably make manual three-plane, two-plane, or single-plane tunnels with steel or diamond keratomes.1 Femtosecond laser –assisted cataract surgery technology can provide reproducible corneal incisions, capsulotomies, and nuclear fragmentation.2,3 The obvious (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Xiaogang Wang, MD, PhD Source Type: research
Erratum for “Corneal Cross-Linking (CXL): Standardizing Terminology and Protocol Nomenclature”
The article “Corneal Cross-Linking (CXL): Standardizing Terminology and Protocol Nomenclature” by Randleman et al., which was published in the November 2017 issue of the Journal of Refractive Surgery (volume 33, number 11, pp. 727–729), has been amended to include a factual correction. An error was identi fied subsequent to its original printing. On page 728, the sentence “Wollensak et al.1 first reported their protocol in 2003, using 3 mW fluence for 30 minutes to achieve a total irradiance of 5.4 mJ/cm2.” should read “Wollensak et al.1 first reported their protocol in 2003, using 3 mW (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: TBD Source Type: research
Pathophysiology of Corneal Scarring in Persistent Epithelial Defects After PRK and Other Corneal Injuries
It has been generally recognized by clinicians for decades that persistence of a corneal epithelial defect beyond 10 days to 3 weeks after trauma, surgery, infection, or disease usually leads to scarring of the corneal stroma underlying the epithelial defect, although little has been written on the etiology of this disorder. Research over the past decade on the critical role of the epithelial basement membrane in the etiology of stromal scarring (late haze or fibrosis) after photorefractive keratectomy (PRK) or stromal scars after microbial keratitis has provided important insights into (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Steven E. Wilson, MD Source Type: research
Changes in Corneal Biomechanical Properties With Different Corneal Cross-linking Irradiances
Corneal cross-linking (CXL) with riboflavin and ultraviolet-A (UVA), first developed by Spoerl et al. in 1997,1 is a treatment modality designed to halt the progression of keratoconus and is considered a less invasive and lower cost option compared with keratoplasty. Unlike other treatments, the main role of CXL is to modify the intrinsic biomechanical properties of the collagen fibers.2 CXL increases the formation of intrafibrillar and interfibrillar covalent bonds by photosensitized oxidation,3 which can increase the mechanical stiffness4 and usually halts the progression of keratoconus and (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Fangjun Bao, MD, PhD Source Type: research
Femtosecond Lenticule Extraction (FLEx) for Spherocylindrical Hyperopia Using New Profiles
Femtosecond lenticule extraction (FLEx) is a refractive surgery procedure in which a femtosecond laser is used to generate an intrastromal lenticule that is removed manually after lifting the flap, as first described in humans during the American Academy of Ophthalmology annual meeting in 2006 using the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) and published in 2008.1 This procedure was refined by eliminating the need for a flap by dissecting and removing the lenticule through a small incision in a procedure known as small incision lenticule extraction (SMILE), and was (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Walter Sekundo, MD, PhD Source Type: research
Five Signs of Unintended Initial Dissection of the Posterior Plane During SMILE
After several years of development, small incision lenticule extraction (SMILE) has achieved somewhat stable efficacy and is seeing increasing popularity among refractive surgeons.1,2 It is advised to dissect the anterior plane first before the posterior plane. However, unintended initial dissection of the posterior plane is a common problem for surgeons who are newly acquainted with SMILE. This increases the difficulty of lenticule dissection and can even lead to complications such as tearing and rupture of the corneal cap or lenticule.3,4 It is essential for surgeons who are learning SMILE (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Ke Zheng, MD Source Type: research
Ray-tracing Analysis of the Corneal Power From Scheimpflug Data
What is the corneal power? Most clinicians will ask for the “K-reading,” neglecting the fact that the keratometer does not measure the power directly. What the keratometer really does is measure the size of the Purkinje I image reflected from the front surface of the cornea in a paracentral ring of approximately 3 mm and calculate the radius of curvature of the convex mirror constituted by the tear film of the cornea. The next step in the classic K-reading is to regard the cornea as a “thin lens” and calculate the dioptric power “K” as a function of the radius according to the paraxial (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Thomas Olsen, MD Source Type: research
Autorefraction Versus Manifest Refraction in Patients With Keratoconus
Keratoconus is a progressive corneal disease in which thinning of the corneal stroma causes the cornea to develop a cone-shaped ectasia, which leads to progressive myopia, irregular astigmatism, and often loss of visual acuity.1,2 Therefore, correctly measuring refractive errors is of paramount importance to assess visual performance, disease progression, and the prescription of visual aids in keratoconus. Several methods to measure refractive errors are currently widely used. A manifest refraction is still considered the gold standard to prescribe spectacles.3,4 This subjective technique was (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - January 10, 2018 Category: Opthalmology Authors: Nienke Soeters, PhD Source Type: research
Postoperative Corneal Asphericity in Low, Moderate, and High Myopic Eyes After Transepithelial PRK Using a New Pulse Allocation
Precise lasers with small laser spots and high repetition rates are now widely used to manipulate the shape of the cornea to correct refractive errors including myopia, hyperopia, astigmatism, and higher order wavefront aberrations and presbyopia.1 SmartSurfACE treatment (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany) is a combination of transepithelial photorefractive keratectomy (PRK) implemented using the Smart Pulse Technology (SCHWIND eye-tech-solutions GmbH), which is a three-dimensional model based on a fullerene structure to improve the smoothness of the ablation beam profile (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - December 12, 2017 Category: Opthalmology Authors: David T. C. Lin, MD, FRCSC Source Type: research
Management and Outcomes of Retained Lenticules and Lenticule Fragments Removal After Failed Primary SMILE: A Case Series
Small incision lenticule extraction (SMILE) is a corneal refractive procedure characterized by predictability, long-term stability of the attempted correction and corneal biomechanics, reduced incidence of intraoperative and postoperative complications, and excellent quality of the visual outcomes.1 –8 Despite the advantages of SMILE over femtosecond laser–assisted LASIK (FS-LASIK) and photorefractive keratectomy (PRK), the procedure is characterized by a steeper learning curve.7,9 A common intraoperative problem for the inexperienced surgeon is the incomplete separation of the lenticule due to (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - December 12, 2017 Category: Opthalmology Authors: Sri Ganesh, MS, DNB Source Type: research
Laboratory Evaluation of the Influence of Decentration and Pupil Size on the Optical Performance of a Monofocal, Bifocal, and Trifocal Intraocular Lens
Various intraocular lens (IOL) designs have been developed to achieve better unaided vision for patients undergoing cataract surgery. Today's standard monofocal IOLs provide excellent distance visual acuity,1 whereas toric and aspheric IOLs optimize the refractive outcome.2,3 Bifocal IOLs provide uncorrected far and near visual acuity, whereas recently introduced trifocal designs flatten out defocus curves and thus additionally grant uncorrected intermediate visual acuity.4,5 To fully exploit the optical capabilities of these IOLs, especially bifocal and trifocal lenses, some requirements need (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - December 12, 2017 Category: Opthalmology Authors: Tamer Tandogan, MD Source Type: research
In Vivo Early Corneal Biomechanical Changes After Corneal Cross-linking in Patients With Progressive Keratoconus
Increased biomechanical stability after CXL has been confirmed by several in vitro studies.1 –5 However, these findings have not yet been consistently supported by in vivo studies, which are often based on parameters such as corneal hysteresis and corneal resistance factor, obtained from the Ocular Response Analyzer (ORA) (Reichert Technologies, Inc., Buffalo, NY).6–11 It has been sugge sted that the biomechanical changes induced by CXL may be too subtle to be measured by the ORA parameters such as corneal hysteresis or corneal resistance factor or have characteristics not measured (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - December 12, 2017 Category: Opthalmology Authors: Riccardo Vinciguerra, MD Source Type: research
Efficacy and Safety Comparison Between Suberoylanilide Hydroxamic Acid and Mitomycin C in Reducing the Risk of Corneal Haze After PRK Treatment In Vivo
Corneal haze formation involves changes in extracellular matrix deposition and keratocyte proliferation, migration, apoptosis, and differentiation of fibroblasts and myofibroblasts.1 –4 Transforming growth factor beta-1 (TGF-β1) has been shown to play a central role in myofibroblast generation and corneal haze formation.5 Myofibroblasts are opaque cells with high contractibility, show de novo expression of alpha-smooth muscle actin (α-SMA), and synthesize extracellular matri x protein. Accumulating literature reveals that myofibroblasts are responsible for corneal haze/fibrosis, but the exact (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - December 12, 2017 Category: Opthalmology Authors: Govindaraj Anumanthan, PhD Source Type: research
