Comparison of Surgically Induced Astigmatism and Morphologic Features Resulting From Femtosecond Laser and Manual Clear Corneal Incisions for Cataract Surgery
Modern cataract surgery has been transitioning to a refractive procedure during the past decade. Considering this, spherical refractive error must be managed by adequate biometry, preexisting astigmatism should be corrected, and surgically induced astigmatism (SIA) must be precisely known. SIA is a form of astigmatism related to the process of healing and scar reshuffling that takes place at the surgical incision. Implantation of aspherical and multifocal intraocular lenses (IOLs) is ineffective unless minimal postoperative astigmatism is achieved.1 Femtosecond laser –assisted cataract surgery (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - May 9, 2018 Category: Opthalmology Authors: Tiago B. Ferreira, MD, FEBOS-CR Source Type: research
Bilateral Keratoconus Induced by Secondary Hypothyroidism After Radioactive Iodine Therapy
Although the mechanism in which thyroid gland dysfunction affects keratoconus is not known, evidence is mounting that an association exists between thyroid hormone alterations and keratoconus disease progression. Previous case reports described keratoconus developing after surgical thyroidectomy,1 acute severe hydrops in a child with Down syndrome and hyperthyroidism,2 acute deterioration of keratoconus induced by hypothyroxemia during pregnancy,3 bilateral keratoconus associated with Hashimoto's disease,4 and keratoconus associated with Alagille syndrome and secondary hypothyroidism.5 In (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - May 9, 2018 Category: Opthalmology Authors: Ramon Lee, MD Source Type: research
Treatment of Corneal Ectasia by Implantation of an Allogenic Corneal Lenticule
Corneal ectasia after LASIK is characterized by progressive corneal thinning and steepening, resulting in moderate to marked visual impairment. Current treatment options include spectacles, rigid gas permeable contact lenses, intracorneal ring segments implantation, corneal cross-linking, and corneal graft.1 Small incision lenticule extraction (SMILE) is an emerging technique for myopia correction and has gained popularity since first reported by Shah et al.2 and Sekundo et al.3 The lenticule is extracted in one piece, which provides the possibility of using the lenticule for other purposes, (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - May 9, 2018 Category: Opthalmology Authors: Meiyan Li, MD, PhD Source Type: research
Refractive Outcomes After Femtosecond Laser –Assisted Cataract Surgery in Eyes With Anterior Chamber Phakic Intraocular Lenses
Femtosecond laser –assisted cataract surgery (FLACS) is an increasingly popular new technology that replaces several manual steps of cataract surgery with a laser. The femtosecond laser generates photodisruption and photoionization of optical transparent tissue through an acoustic shock wave and is used to perform clear corneal incisions, anterior capsulotomy, and lens fragmentation.1 FLACS has the potential to create higher capsulotomy circularity and leads to less endothelial cell reduction due to a lower amount of phacoemulsification energy.2,3 Implantation of intraocular lenses (IOLs) in (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - May 9, 2018 Category: Opthalmology Authors: Gernot Steinwender, MD Source Type: research
Measurement of Posterior Corneal Astigmatism by the IOLMaster 700
Both anterior and posterior corneal astigmatism contribute to total corneal astigmatism. However, “total” corneal astigmatism traditionally has been calculated based on anterior corneal measurements alone using a fixed ratio describing the relationship between the anterior and posterior corneal surfaces. Precise and reliable measurement of total corneal astigmatism and its simple incorporati on into lens formulas is the holy grail of biometry. Calculating intraocular lens (IOL) powers by incorporating additional knowledge of the precise shape of the posterior corneal surface would potentially (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - May 9, 2018 Category: Opthalmology Authors: Benjamin R. LaHood, MBChB, PGDipOphthBS, FRANZCO Source Type: research
The Relationship Between Mechanical Properties, Ultrastructural Changes, and Intrafibrillar Bond Formation in Corneal UVA/Riboflavin Cross-linking Treatment for Keratoconus
Keratoconus is a corneal thinning disease that results in a focally reduced corneal radius of curvature, abnormal wavefront aberrations, and a localized reduction in corneal thickness and stiffness. These aberrations lead to a decline in visual function that ultimately may require corneal transplantation.1 Corneal cross-linking (CXL) with riboflavin and ultraviolet-A (UVA) is an established treatment for progressive keratoconus and currently is the only therapeutic approach that is capable of significantly altering disease progression.2 Available for many years in Europe, this treatment (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Shao-Hsuan Chang, MSE Source Type: research
Visual Performance of a New Extended Depth-of-Focus Intraocular Lens Compared to a Distance-Dominant Diffractive Multifocal Intraocular Lens
Surgeons can choose among several multifocal intraocular lenses (IOLs) to correct presbyopia at the time of cataract removal or refractive lens exchange. Most multifocal IOLs act as bifocal IOLs (ie, they form two primary focal points providing functional distance and near vision). The near add usually ranges between +3.00 and +4.00 diopters (D) at the IOL plane and in the average eye enables a near focal distance between 36 and 48 cm.1 Several studies employing a defocus curve to assess eyes with bifocal IOLs found reduced visual function at intermediate distances, especially with the (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Giacomo Savini, MD Source Type: research
Variation in the Best Fit Sphere Radius of Curvature as a Test to Detect Keratoconus Progression on a Scheimpflug-Based Corneal Tomographer
The introduction of corneal cross-linking (CXL) in 2003 revolutionized the treatment of corneal ectatic diseases such as keratoconus. The activation of riboflavin by ultraviolet-A 370-nm radiation creates an excited molecule that promotes new molecular bonds within and/or between collagen fibers. These new bonds stiffen the corneal stroma and halt keratectasia progression.1,2 The indication for cross-linking is typically clinical progression of the underlying disease. In addition to visual acuity and subjective refraction, topographic and tomographic indices are used to diagnose and monitor (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Nishant Gupta, MS, FRANZCO Source Type: research
Posterior Corneal Astigmatism and Efficacy in Refractive Correction
We read with interest the article by LaHood et al.1 in the November 2017 issue regarding the effect of posterior corneal astigmatism on toric intraocular lens (IOL) calculation for the correction of 2.50 diopters (D) or greater astigmatism. The authors found that the adjustment of the anterior corneal cylinder based on the mean posterior corneal cylinder for toric IOL power calculation did not improve the results in a clinical way. This seems to contradict the advice of Koch et al.2 of reducing the toric power of the IOL in with-the-rule astigmatism cases, and vice versa in against-the-rule (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Jose L. Hern ández-Verdejo, PhD Source Type: research
Two-Year Outcome of a Patient Treated With Phototherapeutic Keratectomy and Autologous SMILE Lenticule Transplantation for Flap-Related Complications Following LASIK
We describe a new technique for the treatment of partial flap loss (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Feng Zhao, MD Source Type: research
Comparison of the Visual Performance After Implantation of Bifocal and Trifocal Intraocular Lenses Having an Identical Platform
Multifocal intraocular lenses (IOLs) have been increasingly preferred in patients receiving cataract removal for the convenience brought to daily life. Diffractive bifocal IOLs comprise concentric rings that form two primary focal points for distance and near vision, whereas new models of trifocal IOLs form three focal distances, providing correction for near, intermediate, and distance vision.1 The visual performance related to the two types of IOLs has become a matter of concern. There have been some clinical reports about the comparison of implantation with a bifocal or trifocal IOL,2 –9 (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Xiaomin Liu, MD Source Type: research
Biological Lenticule Implantation for Correction of Hyperopia: An Ex Vivo Study in Human Corneas
Small incision lenticule extraction (SMILE) performed with femtosecond laser technology has optimized the treatment of refractive errors.1 –4 During the flap-free SMILE procedure, an intrastromal lenticule is created with femtosecond laser and mechanically removed through a minor incision. The extracted corneal lenticules are normally discarded after surgery, but could potentially be used for treatment of other refractive conditions such as hyperopia,5,6 aphakia,7 and presbyopia.8 Lenticule implantation was suggested as a tissue additive procedure in 1966 by Jose Barraquer,9 later followed by (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Iben Bach Damgaard, MD Source Type: research
Optimal Pocket Depth for Corneal Inlays
Changes in refraction following small-aperture corneal inlay implantation (KAMRA; AcuFocus, Irvine, CA) for the treatment of presbyopia are mainly due to hyperopic shift.1 –3 A possible explanation for this is a wound healing response postoperatively, with keratocyte activation and stromal thickening, resulting in changed corneal topography.2,3 The AcuFocus guidelines for implantation suggest that the intrastromal pocket be created at a depth of 200 to 250 µm while maintaining a residual stromal bed of 250 µm.4 We postulated that shallow pocket depth is associated with greater wound healing (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Majid Moshirfar, MD Source Type: research
Early Tomographic Changes in the Eyes of Patients With Keratoconus
Keratoconus is a chronic ectatic disease of the cornea.1 Through changing the natural shape of the cornea into a more cone-like shape due to thinning of the corneal stroma, patients develop astigmatism, reducing their quality of vision and life.2 –4 Ectasia is progressive and can only be stopped with interventions such as cross-linking, otherwise only symptomatic therapy options including spectacles and contact lenses are helpful.5,6 However, sometimes these interventions do not compensate for the deficit in vision effectively so more dras tic treatment such as corneal transplantation might be (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Mehdi Shajari, MD Source Type: research
Through-Focus Optical Bench Performance of Extended Depth-of-Focus and Bifocal Intraocular Lenses Compared to a Monofocal Lens
New IOL developments are focused on improving both far and intermediate vision while maintaining a functional level of near vision, as well as minimizing photopic phenomena associated with high add multifocal IOLs.1 One example of these new developments is the low add bifocal IOLs (AcrySof SV25T0; Alcon Laboratories, Inc., Fort Worth, TX, and TECNIS ZKB00; Abbott Medical Optics, Inc., Santa Ana, CA) that reduce the distance between the far and near focus generated by the IOL and therefore minimize the size of the associated halo.1,2 Another new technology is the concept of the extended (Source: Journal of Refractive Surgery)
Source: Journal of Refractive Surgery - April 11, 2018 Category: Opthalmology Authors: Young-Sik Yoo, MD Source Type: research
