LASIK Eye Surgery

• “A novel application of pulsed electronic speckle pattern interferometry (PulseESPI) techniques in important corneal elasticity measurements is presented in this pilot study.”¹
• “For laser-ablative procedures like laser-assisted in situ keratomileusis, it has been found that elastic properties of the cornea have a role in the outcome of corneal refractive surgery, while for optimal ablative laser power calculations this measurement method may possibly be helpful.”
• “It may also help in earlier diagnosis of degenerative corneal disorders such as keratoconus.”

Researchers from Electronics Engineering Department, Politecnico di Torino, Torino - Italy; have presented an article titled: “Broader corneal characterization with PulseESPI applied to elasticity measurements.”

The researchers from Electronics Engineering Department, Politecnico di Torino, Torino - Italy; have concluded:

• “PulseESPI may help in important corneal elasticity measurements used for complication-free optimized ophthalmic surgery.”
• “It seems to be a promising method to conduct stress-related investigations on biological samples.”
• “To our knowledge, this is the first time that PulseESPI has been used for such ophthalmic measurements.”

The researchers from Electronics Engineering Department, Politecnico di Torino, Torino - Italy; have also noted:

• “The approach of this study is to observe dynamic behavior of cornea against stresses as mapped with PulseESPI.”
• “For this purpose, strain was induced to the cornea using a fine rod with a mechanical vibrator.”
• “It was found that cornea has a response pattern to the dynamic stressing.”
• “Its surface exhibits a resonance frequency which can be measured with PulseESPI.”
• “This information of resonance frequency can be characteristic to the cornea.”

(1) Gualini MM, Iqbal S, Sixt W, Khan WA, Zulfiqar K: Broader corneal characterization with PulseESPI applied to elasticity measurements. Eur J Ophthalmol. 2010 Jan 12;20(2):306-309; (Article in Press)

Tags: cornea corneal refractive surgery elastic properties elasticity eye surgery laser-ablative procedures laser-assisted in situ keratomileusis resonance frequency

Abbott has reported that “… it has received U.S. Food and Drug Administration (FDA) approval for the TECNIS® Multifocal 1-Piece intraocular lens (IOL) for cataract patients with and without presbyopia.”

More from a Release dated March 10, sourced from Abbott:
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Tags: aspheric lenses cataractous lens distance vision intermediate vision multifocal intraocular lens multifocal IOLs near vision wavefront-designed lens

• “… effects and possible mechanisms of rat bone marrow mesenchymal stem cells (BMSCs) transplantation on light-damaged retinal structure and the apoptosis of photoreceptors.”¹

Researchers from Peking University Third Hospital, Peking University Eye Center, Beijing, China; have presented an article titled: “Effects of Bone Marrow Mesenchymal Stem Cells Transplantation on Light-Damaged Retina.”

The researchers from Peking University Third Hospital, Peking University Eye Center, Beijing, China; have concluded:

• “BMSCs subretinal transplantation could inhibit photoreceptors apoptosis and slow down retinal damage in light-damaged eyes.”
• “BMSCs could express bFGF (in vitro) and BDNF (in vitro and in vivo), pointing to potential trophic and protective effects on light-damaged retinas.”

The researchers from Peking University Third Hospital, Peking University Eye Center, Beijing, China; have also noted:

• “4′ 6- diamidino -2-phenylindole (DAPI)-labeled BMSCs were transplanted into the subretinal space of light-damaged Sprague-Dawley (SD) rats 10 days after exposure.”
• “BMSCs were cultivated with the supernatant of homogenized retina (SHR).”
• “Compared with the phosphate buffered solution (PBS) injection group and the light damage group, the outer nuclear layer (ONL) contained significantly more cells and the percentage of apoptotic ONL cells was significantly reduced in the BMSCs transplantation group.”
• “Most DAPI-labeled BMSCs expressed brain-derived neurotrophic factor (BDNF).”
• “There was elevated basic fibroblast growth factor (bFGF) and BDNF immunoreactivity in the retinas of the BMSCs transplantation group, as compared with the light damage group.”
• “In vitro culture showed that 10% BMSCs changed from fusiform shape to multipolar shape.”
• “A fraction of cells expressed MAP2 or GFAP, and some cells expressed bFGF or BDNF when cultivated with light-damaged SHR for 7 days.”

(1) Zhang Y, Wang W: Effects of Bone Marrow Mesenchymal Stem Cells Transplantation on Light-Damaged Retina. Invest Ophthalmol Vis Sci. 2010 Mar 5; (Article in Press)

Tags: apoptosis apoptotic basic fibroblast growth factor BDNF Beijing bFGF BMSCs bone marrow brain-derived neurotrophic factor China cultivated effects elevated fraction fusiform gene therapy GFAP homogenized retina immunoreactivity inhibit injection group light damage group light-damaged light-damaged eyes light-damaged retinas light-damaged SHR light-damaged Sprague-Dawley rats MAP2 mechanisms mesenchymal stem cells multipolar ONL cells outer nuclear layer Peking University Eye Center Peking University Third Hospital phosphate buffered solution photoreceptors photoreceptors apoptosis protective effects rat bone reduced retinal damage retinal structure slow down subretinal space subretinal transplantation supernatant transplantation transplantation group trophic

• “… a patient who had a perforating eyelid injury that extended to the brain stem.”¹

Researchers from Kyorin Eye Center, Kyorin University School of Medicine, Tokyo, Japan; have presented an article titled: “Perforating eyelid injury extending to the brain stem in a 17-year-old woman: a case report.”

The researchers from Tokyo have concluded:

• “We recommend that MRI be performed on the orbit and brain in patients who appear to have symptoms that are inconsistent with the observed injury and when a severe orbitocranial injury is suspected.”

The researchers from Tokyo have also noted:

• “A 17-year-old Japanese woman complained of decreased vision in her right eye, with severe ocular pain and headaches, after the metal tip of an umbrella struck her upper right eyelid accidentally.”
• “Her vision in the right eye decreased to light perception with commotio retinae, intraretinal hemorrhage, and severe lid swelling.”
• “Magnetic resonance imaging (MRI) demonstrated edema of the head of the caudate nucleus and putamen, and the edema extended to the hypothalamus.”
• “The MRI findings indicated that the umbrella tip had penetrated through the eyelid and the posterior orbital wall.”
• “Vision improved to 20/50 in the right eye, with subretinal fibrosis caused by the choroidal rupture.”

(1) Noda E, Inoue M, Yoshikawa-Kobayashi I, Nagamoto T: Perforating eyelid injury extending to the brain stem in a 17-year-old woman: a case report. J Med Case Reports. 2010 Jan 21;4:18.

Tags: 17-year-old accidentally brain brain stem caudate nucleus choroid choroidal rupture commotio retinae decreased edema extended eyelid eyelid injury fibrosis headaches hypothalamu inconsistent injury intraretinal hemorrhage Japan Kyorin Eye Center Kyorin University School of Medicine lid swelling light perception magnetic resonance imaging metal tip MRI findings observed injury ocular pain orbit orbitocranial pain penetrated perforating eyelid injury posterior orbital wall putamen right eye severe subretinal swollen eyelid symptoms Tokyo umbrella struck umbrella tip upper right eyelid vision

• “Supratarsal crease fixation in the Asian patient can provide a more open-eyed, awake look without compromising their ethnic appearance.”¹

Researchers from Willow Bend Wellness Center, Lam Facial Plastic Surgery Center & Hair Restoration Institute, Plano, Texas, USA; have presented an article titled: “Supratarsal Crease Creation in the Asian Upper Eyelid.”

The researchers from Lam Facial Plastic Surgery Center & Hair Restoration Institute have also noted:

• “A conservative supratarsal crease height and conservative to no removal of postseptal fat help to ensure this natural-appearing result.”
• “With the full-incision method, consistently excellent results have been achieved with durable crease fixation despite a prolonged recovery time.”
• “The supratarsal crease fixation provides an excellent method for the younger patient seeking cosmetic eyelid enhancement.”
• “However, for the aging Asian patient, the complexity of the strategy is greater.”

(1) Lam SM, Karam AM: Supratarsal Crease Creation in the Asian Upper Eyelid. Facial Plast Surg Clin North Am. 2010 Feb;18(1):43-47.

Tags: aging Asian patient aging patient anti-aging Asian Asian eyelid surgery Asian patient Asian upper eyelid awake look complexity compromising conservative consistently cosmetic eyelid cosmetic surgery crease crease height durable enhancement enhancement surgery ensure ethnic appearance excellent eyelid surgery fixation full-incision greater Lam Facial Plastic Surgery Center 038 Hair Restoration Institute natural-appearing open-eyed Plano postseptal fat prolonged recovery time removal result results strategy supratarsal supratarsal crease fixation Texas USA Willow Bend Wellness Center younger patient

• “Selective control of cellular response to polymeric biomaterials is an important consideration for many ocular implant applications.”¹
• “In particular, there is often a need to have one surface of an ophthalmic implant capable of promoting cell attachment while the other needs to be resistant to this effect.”

Researchers from Nanotechnology and Integrated Bio-Engineering Centre, School of Engineering, University of Ulster, Newtownabbey, Northern Ireland; have presented an article titled: “Lens epithelial cell response to atmospheric pressure plasma modified poly(methylmethacrylate) surfaces.”

The researchers from Nanotechnology and Integrated Bio-Engineering Centre have also noted:

• “In this study, an atmospheric pressure dielectric barrier discharge (DBD) has been used to modify the surface region of poly(methyl methacrylate) (PMMA), a well established ocular biomaterial, with the aim of promoting a controlled response to human lens epithelial cells (LEC) cultured thereon.”
• “The DBD plasma discharge environment has also been employed to chemically graft a layer of poly(ethylene glycol) methyl ether methacrylate (PEGMA) onto the PMMA and the response to LEC likewise determined.”
• “Two different molecular weights of PEGMA, namely 1000 and 2000 MW were used in these experiments.”
• “The LEC response to DBD treated polystyrene (PS) samples has also been examined as a positive control and to help to further elucidate the nature of the modified surfaces.”
• “The LEC adhered and proliferated readily on the DBD treated PMMA and PS surfaces when compared to the pristine polymer samples which showed little or no cell response.”
• “The PMMA and PS surfaces that had been DBD grafted with the PEGMA(1000) layer were found to have some adhered cells.”
• “However, on closer inspection, these cells were clearly on the verge of detaching.”
• “In the case of the PEGMA(2000) grafted surfaces no cells were observed indicating that the higher molecular weight PEGMA has been able to attain a surface conformation that is capable of resisting cell attachment in vitro.”

(1) D’Sa RA, Burke GA, Meenan BJ: Lens epithelial cell response to atmospheric pressure plasma modified poly(methylmethacrylate) surfaces. J Mater Sci Mater Med. 2010 Feb 27; (Article in Press)

Tags: adhered applications atmospheric pressure cellular response chemically graft controlled response cultured DBD grafted DBD plasma discharge DBD treated polystyrene detaching dielectric barrier discharge environment human lens epithelial cells Ireland lens epithelial cell modified surfaces molecular weights molecule Nanotechnology and Integrated Bio-Engineering Centre Newtownabbey no cell response Northern Ireland ocular biomaterial ocular implant one surface ophthalmic implant PEGMA plasma modified PMMA polyethylene glycol methyl ether methacrylate polymer polymeric biomaterials polymethyl methacrylate polystyrene positive control pristine proliferated promoting cell attachment resistant samples w School of Engineering selective control surface conformation surface region United Kingdom University of Ulster verge well established

• “To evaluate the shape of posterior corneal surface in normal myopic and myopic astigmatism eyes and the changes following LASIK and Epi-LASIK.”¹

Researchers from Refractive Surgery Center, Tianjin Eye Hospital & Eye Institute, Tianjin Medical University, Tianjin, China; have presented an article titled: “The Shape of Posterior Corneal Surface in Normal, Post-LASIK, and Post-Epi-LASIK Eyes.”

The researchers from Tianjin Eye Hospital & Eye Institute have concluded:

• “The shape of normal posterior corneal surface exhibited obvious regional disparities and radial asymmetry.”
• “The displacement following LASIK was observed as time-dependent changes that protruded at an early stage but then returned to original levels 6 months after surgery.”
• “On the other hand, the displacement following Epi-LASIK showed as region-dependent changes that could be divided into central and peripheral parts, which displayed backward and forward shift trends, respectively.”

The researchers from Tianjin Eye Hospital & Eye Institute have also noted:

• “A total of 152 eyes were included in this study.”
• “The posterior corneal elevation was measured with Scheimpflug imaging (Pentacam, Oculus) before LASIK or Epi-LASIK and at 1 and 6 months after the surgeries along the 4 optical zones (center, 2-mm, 4-mm, and 6-mm diameters) as a function of the meridian.”
• “For normal eyes, the heights were lower in the vertical meridian than in the horizontal meridian, and were also lower in the superior hemisphere than in the inferior hemisphere.”
• “In post-LASIK eyes, almost all regions protruded 1 month after surgery except for the 6-mm diameter, where it exhibited a slight but not significant (p=0.731) backward displacement.”
• “The various elevations returned to original levels 6 months after LASIK.”
• “In the post-Epi-LASIK group, there was a significant backward displacement at the center and 2-mm regions postoperatively.”
• “Moreover, there was no shift at the 4-mm diameter, and the 6-mm showed a progressive forward shift.”

(1) Zhang L, Wang Y: The Shape of Posterior Corneal Surface in Normal, Post-LASIK, and Post-Epi-LASIK Eyes. Invest Ophthalmol Vis Sci. 2010 Mar 5; (Article in Press)

Tags: 6 months after surgery astigmatism backward before LASIK or Epi- central changes changes following LASIK China have presented an article disparities displacement divided early stage Epi-LASIK following Epi-LASIK following LASIK forward forward shift heights were lower hemisphere horizontal meridian inferior hemisphere LASIK meridian myopic no shift normal normal eyes Oculus optical zones original levels Pentacam peripheral post-LASIK posterior corneal elevation posterior corneal surface progressive protruded radial asymmetry Refractive Surgery Center region-dependent regional returned Scheimpflug imaging shape shape of normal posterior corneal surface shift trends significant slight superior Tianjin Tianjin Eye Hospital 038 Eye Institute Tianjin Medical University time-dependent changes vertical meridian

Dolores Takemoto, Professor of Biochemistry, from Kansas State University, has said:

• “Any time there’s a drop in oxygen within the body, Cx46 appears …”

A Release dated March 9, sourced from Kansas State University informs:

• ‘According to the data, Coonexin46, or Cx46, appears in the body during these levels of low oxygen. Besides the eye, which is one of the body’s only naturally occurring hypoxic tissue, Cx46 also is present in cancer cells since the cells seal themselves off from the oxygen carried by the blood vessels, thus creating a hypoxic environment.’
• ‘Takemoto believes the findings will lead to serious advancements in treating retinoblastoma, a cancer that forms in the tissue of the retina — the light-sensitive layers of nerve tissue on the back of the eye. It occurs in 300 U.S. children under the age of 5 each year, according to the National Cancer Institute.’

More from the Release dated March 9, sourced from Kansas State University:
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Tags: back of the eye blood pressure problems blood vessels breast cancer cancer cells cancer-aiding protein chronic heart disease Coonexin46 correlation Cx46 deficiency of oxygen double-stranded drop in oxygen expression gap junction gene therapy glaucoma heart attacks human eye hypoxic environment hypoxic stage hypoxic tissue injected monthly interfere ischemia of the brain Kansas State University lens light-sensitive layers low oxygen naturally occurring nerve tissue oxygen preserve eyesight protein protein kinase C gamma retina retinal ischemia retinoblastoma RNA molecules siRNA small interfering ribonucleic acid specific gene the eye tissue too late toxicology

• “Epidemiological research has shown that multifocal spectacle wearers (bifocal and progressive addition lenses, PALs) are more than twice as likely to fall compared with non-multifocal spectacle wearers with this risk further increasing when negotiating stairs.”¹

Researchers from Division of Medical Engineering, School of Engineering Design & Technology, University of Bradford, Bradford, West Yorkshire, England, United Kingdom; have presented an article titled: “Use of single-vision distance spectacles improves landing control during step descent in well-adapted multifocal lens-wearers.”

The researchers from Bradford have concluded:

• “Use of single-vision distance spectacles lead to improvements in landing control, consistent with individuals being more certain regarding the precise height of the lower floor level.”
• “This was attributed to having a view of the foot, step edge and immediate floor area that was not blurred, magnified or doubled and that did not suffer from image jump or peripheral distortions.”
• “These findings provide further evidence that use of single-vision distance lenses in everyday locomotion may be advantageous for elderly multifocal wearers who have a high risk of falling.”

The researchers from Bradford have also noted:

• “The present study investigated whether step/stair descent safety is improved by using single-vision distance lenses.”
• “From a stationary standing position on top of a block, twenty long-term multifocal wearers stepped down (from different block heights) onto a lower level wearing either bifocal, PALs or single-vision distance lenses.”
• “Use of single-vision distance spectacles lead to an increased single-limb support time, a reduced ankle and knee angle and vertical centre-of-mass velocity at contact with the lower level, and a reduced ankle angular velocity and vertical centre-of-mass velocity during initial landing (p < 0.03).”
• “These findings indicate that landing occurred in a more controlled manner when wearing single-vision distance spectacles, rather than tending to ‘drop’ onto the lower level as occurred when wearing bifocals or PALs.”

(1) Timmis MA, Johnson L, Elliott DB, Buckley JG: Use of single-vision distance spectacles improves landing control during step descent in well-adapted multifocal lens-wearers. Invest Ophthalmol Vis Sci. 2010 Mar 5; (Article in Press)

Tags: ankle angular velocity bifocal lenses block heights blurred blurry Bradford contact with control did not suffer distance vision eyeglasses distortion Division of Medical Engineering doubled drop lower level elderly eyeglasses wearers England epidemiological research everyday locomotion eyeglasses wearers falling floor area floor level further increasing high risk image jump immediate floor area improvements in landing control improves initial landing knee angle landing landing control long-term lower floor level lower level magnified more certain more controlled manner multifocal eyeglasses multifocal lens-wearers multifocal lenses multifocal spectacle wearers multifocal wearers negotiating negotiating stairs non-multifocal spectacle wearers not blurred PALs lenses peripheral peripheral distortions precise height progressive addition lenses reduced reduced ankle risk risk factor School of Engineering Design 038 Technology single-limb support time single-vision distance eyeglasses single-vision distance lenses single-vision distance spectacles spectacle wearers stairs stationary standing position steep descent step descent step edge step-stair descent safety stepped down to fall top of a block twice as likely United Kingdom University of Bradford vertical centre-of-mass velocity view of the foot well-adapted West Yorkshire

Riboflavin is also commonly known as vitamin B2 (E101).

Riboflavin/UVA crosslinking treatment often involves anesthetic eye drops, corneal deepithlization and a specially prepared 0.1% riboflavin solution; followed by UVA irradiation (370 nm) at five minute intervals for 30 minutes.

LASIK - Vitamin B2 Collagen Crosslinking. How Safe is UV Irradiation of the Eye?

• “Riboflavin/UVA crosslinking (CXL) of corneal collagen is a novel method to stabilize corneal mechanical properties and prevent progression of keratectasias.”¹

Researchers from Department of Ophthalmology, University of Wuerzburg, Wuerzburg, Germany; have presented an article titled: “Influence of Corneal Collagen Crosslinking With Riboflavin and Ultraviolet-A Irradiation on Excimer Laser Surgery.”

The researchers from Department of Ophthalmology, University of Wuerzburg, Wuerzburg, Germany; have concluded:

• “CXL reduces the amount of refractive change after myopic LASIK.”
• “While laser ablation rate is unaffected, CXL results in an increased flap thickness.”
• “This study suggests a need for adjustment of microkeratome and laser parameters for LASIK after CXL and indirectly endorses the theory of a direct stiffening effect of CXL.”

The researchers from Department of Ophthalmology, University of Wuerzburg, Wuerzburg, Germany; have also noted:

• “The study investigates whether CXL influences ablation rate, flap thickness and refractive results of Excimer laser procedures ex vivo.”
• “In enucleated porcine eyes corneal epithelium was removed and CXL performed with riboflavin 0.1% and UVA radiation (365nm, 3mW/cm(2)) for 30min.”
• “Controls received epithelial abrasion only.”
• “Diffusion of riboflavin through the cornea was assessed using infrared-excited 2-photon microscopy of riboflavin autofluorescence combined with second harmonic generation of fibrillar collagen.”
• “During phototherapeutic keratectomy corneal thickness was measured by optical coherence pachymetry.”
• “During myopic LASIK flap thickness of microkeratome cuts was measured and the induced refractive change assessed by Placido topography.”
• “Data were analyzed by Shapiro-Wilk test and Student’s t-test.”
• “Multiphoton-imaging showed a rapid (30min) and even distribution of riboflavin throughout the corneal stroma.”
• “No difference in ablation rate was measured in treated and untreated corneas (p=0.90).”
• “Mean flap thickness was increased by 44% in crosslinked corneas (p<0.01).”
• “After myopic LASIK for 4 dpt up to 25 dpt, mean corneal refractive change was reduced in CXL-treated eyes by 20.1% (p<0.05).”
• “This effect was less pronounced in thinner flaps.”

(1) Kampik D, Ralla B, Keller S, Hirschberg M, Friedl P, Geerling G: Influence of Corneal Collagen Crosslinking With Riboflavin and Ultraviolet-A Irradiation on Excimer Laser Surgery. Invest Ophthalmol Vis Sci. 2010 Mar 5; (Article in Press)

Tags: ablation rate CCL corneal collagen corneal epithelium CXL CXL-treated eyes Department of Ophthalmology epithelial abrasion ex vivo excimer laser fibrillar collagen flap thickness generation Germany influences infrared-excited 2-photon microscopy LASIK microkeratome cuts multiphoton-imaging Placido topography refractive changerefractive change refractive results riboflavin autofluorescence second harmonic thinner flaps University of Wuerzburg Wuerzburg