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corneal refraction

Stephanie Kearney, Lisa O'Donoghue, Laura K Pourshahidi, Patrick Richardson, Eamon Laird, Martin Healy, Kathryn J Saunders
BACKGROUND: Conjunctival ultraviolet autofluorescence (CUVAF) has been used as a biomarker of time spent outdoors. Smaller CUVAF area is associated with myopia in southern hemisphere cohorts. Further research is required to determine if this association is replicated in northern latitudes and whether average CUVAF intensity is a valuable metric. This prospective study explored the association between myopia, CUVAF (area and intensity) and additional indicators of sun exposure (vitamin D3 and self-reported sun exposure preferences) across seasons at a location of 55° north...
August 16, 2018: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
Mehdi Naderi, Siamak Sabour, Soheila Khodakarim, Farid Daneshgar
BACKGTOUND: Photorefractive keratectomy (PRK) is used for a wide range of refractive errors such as low to moderate myopia, hyperopia and astigmatism. While many improvements have been made in laser application and accuracy as well as the modes of corneal flap removal, and although the results are somewhat predictable, regression of refractive errors is still a common complaint among the patients undergoing refractive surgery with Excimer Laser. We aimed to determine related factors of regression following photorefractive keratectomy (PRK) in different types of refractive errors...
August 14, 2018: BMC Ophthalmology
S H Gan, L L Deng, X J Zhou, J L Yi, Q Q Zhou, Y P Li, R Zhou
Objective: To assess the prevalence of visual impairment and the influencing factors among rural residents aged 60 years and above in Yugan county, Jiangxi province. Researchers analyzed influencing factors and provided scientific rationale for blindness prevention and control. Methods: Stratified cluster random sampling was used in randomly selecting 3 789 rural residents aged ≥ 60 in Yugan county. Eligible residents were invited to receive ophthalmic examinations and epidemiological investigations. Multivariate logistic regression was performed to analyze any influencing factors...
August 11, 2018: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
Yasmine Maher Shaaban, Tamer Abdel Fattah Badran
Purpose: The purpose of this study was to compare the effects of three different corneal refractive surgeries: microkeratome laser in situ keratomileusis (LASIK), femtosecond laser in situ keratomileusis (FS-LASIK) and femtosecond small incision lenticule extraction (FS-SMILE) on 6-month postoperative stability of tear film to provide a basis for selection of operative procedures. Patients and methods: This is a prospective, randomized, comparative study that included 90 eyes of three equal groups of patients...
2018: Clinical Ophthalmology
Michele Lanza, Robert Koprowski, Mario Bifani Sconocchia
BACKGROUND: To improve accuracy of IOLMaster (Carl Zeiss, Jena, Germany) in corneal power measurement after myopic excimer corneal refractive surgery (MECRS) using multivariate polynomial analysis (MPA). METHODS: One eye of each of 403 patients (mean age 31.53 ± 8.47 years) was subjected to MECRS for a myopic defect, measured as spherical equivalent, ranging from - 9.50 to - 1 D (mean - 4.55 ± 2.20 D). Each patient underwent a complete eye examination and IOLMaster scan before surgery and at 1, 3 and 6 months follow up...
August 13, 2018: Biomedical Engineering Online
Muriel Schornack, Cherie Nau, Amy Nau, Jennifer Harthan, Jennifer Fogt, Ellen Shorter
PURPOSE: To describe patient-specific outcomes of scleral lens wear utilizing a variety of lens designs across multiple practice settings as reported in an international practitioner survey. METHODS: An electronic survey was administered to eye care providers who prescribe scleral lenses in which they were asked to describe their most recently examined established scleral lens patient. Data was collected on patient characteristics, lens designs, wearing schedules, care products, and visual and physiological outcomes of lens wear...
August 8, 2018: Contact Lens & Anterior Eye: the Journal of the British Contact Lens Association
Ana Amorim-de-Sousa, Ana Cláudia Vieira, José Manuel González-Méijome, António Queirós
PURPOSE: Corneal front-surface asphericity is directly related with the optical quality of the eye and with contact lenses fitting. The purpose of this study was to evaluate the corneal asphericity as a function of age, sex, and refractive error measured with autokeratometry and corneal topography and its long-term changes (5- to 10-year period). METHODS: The asphericity and corneal curvature were obtained with the autorefractometer/autokeratometer NIDEK ARK-700A and with the videokeratoscope MODI 2...
August 7, 2018: Eye & Contact Lens
Bartlomiej J Kaluzny, Ilona Piotrowiak-Slupska, Magdalena Kaszuba-Modrzejewska, Joanna Stachura, Samuel Arba-Mosquera, Shwetabh Verma
AIM: To evaluate refractive and visual outcomes of photorefractive keratectomy (PRK) to treat high hyperopia using an aberration-neutral profile and large ablation zone. METHODS: This was a retrospective, consecutive observational case series at the Oftalmika Eye Hospital, Bydgoszcz, Poland. We included 51 consecutive eyes of 34 patients who underwent alcohol-assisted PRK to correct hyperopia within the range of +3.6 to +6.15 D (mean+4.61±0.67 D). Procedures were performed with an Amaris 750S excimer laser (Schwind eye-tech-solutions GmbH, Kleinostheim, Germany) using an aberration-neutral profile and a 10 mm total ablation zone...
August 9, 2018: British Journal of Ophthalmology
Chang Ho Yoon, Mee Kum Kim
PURPOSE: To investigate the effect of surgically induced corneal astigmatism (SICA) and total corneal astigmatism (TCA) estimation on the anterior corneal astigmatism (ACA)-based toric intraocular lens (IOL) calculation. METHODS: Data from preoperative and postoperative corneal astigmatism, postoperative visual acuities, and refractive outcomes were collected. The incision was superior in with the rule anterior corneal astigmatism (WTRA) eyes and temporal in against the rule anterior corneal astigmatism eyes...
August 2018: Korean Journal of Ophthalmology: KJO
Manuel Rodriguez-Vallejo, Diego Montagud, Juan A Monsoriu, Vicente Ferrando, Walter D Furlan
PURPOSE: To assess the peripheral refraction induced by Fractal Contact Lenses (FCLs) in myopic eyes by means of a two-dimensional Relative Peripheral Refractive Error (RPRE) map. MATERIALS AND METHODS: This study involved 26 myopic subjects ranging from -0.50 D to -7.00 D. FCLs prototypes were custom-manufactured and characterized. Corneal topographies were taken in order to assess correlations between corneal asphericity and lens decentration. Two-dimensional RPREs were measured with an open-field autorefractor at 67 points, covering the central 60 × 30 degrees of the visual field...
August 8, 2018: Current Eye Research
Inger Heleen Noor, Theo G Seiler, Kai Noor, Theo Seiler
PURPOSE: To report 3 cases with continued long-term flattening after corneal cross-linking (CXL) for keratoconus and to determine its prevalence. METHODS: Case series. RESULTS: Three eyes of three patients presented with an ongoing corneal flattening over 10 years after CXL in the absence of corneal opacities. Of the initial 433 eyes treated with CXL between 2005 to 2007, only 45 eyes completed the 10-year follow-up period, indicating a prevalence of 6...
August 1, 2018: Journal of Refractive Surgery
Ofira Zloto, Irina S Barequet, Alon Weissman, Orit Ezra Nimni, Yoav Berger, Noa Avni-Zauberman
PURPOSE: To examine the clinical characteristics, treatments, and prognosis of all cases of infectious keratitis resistant to conventional therapy and treated by photo-activated chromophore for keratitis corneal cross-linking (PACK-CXL) in one institution between 2012 and 2016. METHODS: A database search of patients who underwent PACK-CXL (ultraviolet-A for 10 minutes for irradiance of 9 mW/cm2 ) for infectious keratitis unresponsive to medical treatment at a tertiary care hospital was conducted...
August 1, 2018: Journal of Refractive Surgery
Raphael Atia, Lea Jouve, Otman Sandali, Laurent Laroche, Vincent Borderie, Nacim Bouheraoua
PURPOSE: To evaluate and compare epithelial remodeling after standard corneal cross-linking (S-CXL) and iontophoresis-assisted CXL (I-CXL) in eyes with keratoconus by anterior segment optical coherence tomography (AS-OCT). METHODS: In this prospective, observational study, AS-OCT and corneal topography were performed before and 1, 3, and 6 months after surgery. Corneal pachymetry was performed and epithelial and stromal thicknesses (central and 16 points on the 6-mm central zone) and the maximum simulated keratometry value (Kmax) were measured...
August 1, 2018: Journal of Refractive Surgery
Daniela Lyra, Guilherme Ribeiro, Leonardo Torquetti, Paulo Ferrara, Aydano Machado, João Marcelo Lyra
PURPOSE: To evaluate the predictability of asphericity and average keratometry in patients with keratoconus after implantation of intrastromal corneal ring segments (ICRS) using artificial intelligence. METHODS: This study included 209 eyes of 160 patients with keratoconus (grades I, II, and III) who had ICRS implanted. The 160 arc length Ferrara ICRS was implanted in all patients. ICRS thickness varied from 150 to 250 μm. Pentacam (Oculus Optikgeräte, Wetzlar, Germany) corneal tomography parameters, clinical data, and ICRS data formed the basis of the 39 studied parameters...
August 1, 2018: Journal of Refractive Surgery
Ikhyun Jun, David Sung Yong Kang, Samuel Arba-Mosquera, Eung Kweon Kim, Kyoung Yul Seo, Tae-Im Kim
PURPOSE: To investigate the clinical outcomes, vector parameters, and corneal aberrations of corneal wavefront-guided (CWFG) transepithelial photorefractive keratectomy (PRK), according to epithelial thickness. METHODS: This retrospective, comparative case series study included 91 eyes (91 patients) that underwent CWFG transepithelial PRK for myopic astigmatism. Epithelial thickness was less than 50 μm in 48 patients and 60 μm or greater in 43 patients. Clinical outcomes, including visual acuity, manifest refraction, vector parameters, and corneal wavefront aberration, were compared between the two groups...
August 1, 2018: Journal of Refractive Surgery
Rohit Shetty, Himnashu Matalia, Chinnappaiah Nandini, Ashwatha Shetty, Pooja Khamar, Tushar Grover, Abhijit Sinha Roy
PURPOSE: To compare ocular and corneal aberrometric outcomes of wavefront-guided (WFG) LASIK and small incision lenticule extraction (SMILE). METHODS: This was a prospective, interventional study where 48 eyes (24 patients) underwent SMILE (Carl Zeiss Meditec, Jena, Germany) and 58 eyes (29 patients) underwent WFG LASIK (Abbott Medical Optics, Abbott Park, IL). Visual acuity and ocular surface disease index were assessed preoperatively and 1 and 3 months postoperatively...
August 1, 2018: Journal of Refractive Surgery
Benjamin R LaHood, Michael Goggin, Simone Beheregaray, Nicholas H Andrew, Adrian Esterman
PURPOSE: To compare "total keratometry" measurements with Goggin nomogram adjusted anterior keratometry (GNAK) for toric intraocular lens calculation. METHODS: Routine biometry provided measured total keratometry values from which astigmatism was derived. The Goggin nomogram was applied to anterior keratometry values on the same eyes to provide nomogram-adjusted anterior keratometry values (GNAK) that estimate total corneal astigmatism. The agreement between total keratometry and GNAK was analyzed...
August 1, 2018: Journal of Refractive Surgery
Paul D Chamberlain, Ildamaris Montes de Oca, Ravi Shah, Li Wang, Mitchell P Weikert, Sumitra S Khandelwal, Zaina Al-Mohtaseb
PURPOSE: To determine whether any of three keratometry devices is superior to the others in predicting the ideal toric intraocular lens (IOL) alignment meridian. METHODS: A retrospective review was performed to identify patients who underwent cataract phacoemulsification with toric IOL implantation from November 2014 to November 2016 at a single academic institution. For each patient, corneal measurements were performed with an optical low-coherence reflectometer/autokeratometer (OLCR), a dual Scheimpflug/Placido analyzer, and a color light-emitting diode (LED) topographer...
August 1, 2018: Journal of Refractive Surgery
Om Prakash Pant, Ji-Long Hao, Dan-Dan Zhou, Fan Wang, Bing-Jie Zhang, Cheng-Wei Lu
Small incision refractive lenticule extraction (SMILE) is a femtosecond laser technique to correct myopia and myopic astigmatism. Herein, we report a technique where intrastromal lenticule obtained from the SMILE procedure served as a graft for lamellar keratoplasty in the management of a limbal dermoid. An 18-year-old woman presented to the clinic with a corneal-limbal mass in the right eye. Slit-lamp examination revealed a vascularized circular mass of approximately 6 mm × 5 mm, which was attached at 7 o'clock in the inferotemporal region of the corneal limbus; this suggested limbal dermoid...
August 8, 2018: Journal of International Medical Research
James McMillan
Serial observations obtained over more than eight years and 10,000 patient encounters in a general ophthalmology practice serving a population highly prone to chronic vitamin D (D3) deficiency, facilitated by the Oculus Pentacam Scheimpflug imaging system (Oculus Optikgeräte GmbH, Wetzlar, Germany), resulted in the recognition of consistent, predictable, and highly reproducible patterns of mechanical, optical, and physiologic change in the cornea and other ocular structures correlated to adequate vs. inadequate vitamin D availability...
June 5, 2018: Curēus
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