Diffuse lamellar keratitis (DLK) is a sterile inflammation of the cornea which may occur after refractive surgery, such as LASIK.[1] Its incidence has been estimated to be 1 in 500 patients,[2] though this may be as high as 32% in some cases.[3]
Risk factors
DLK is predominantly associated with Lasik, as the creation of a flap creates a potential space for cells to accumulate. Individuals with atopic conditions with pre-existing allergic conjunctivitis, or ocular rosacea, are more prone to developing the condition after surgery. Some authors have reported that moderate to severe eye allergies and chronic allergic conjunctivitis are an absolute contraindication to the LASIK procedure.[4] This is in distinction to findings of earlier studies.[5] Keratitis can also occur after photorefractive keratectomy (PRK), although because it occurs in the setting of infection, it is distinct from the sterile infiltrates of DLK.[6] DLK can also occur following myopic keratomileusis, in which a disc of corneal tissue is removed, shaped and sutured back into place, although this technique is more historical, having been replaced by Lasik and PRK.[7]
Signs and symptoms
Patients typically present within one week of surgery with eye pain, photophobia, conjunctivitis, or excessive tear production.
Pathology
DLK is usually seen after refractive surgery. Neutrophils infiltrate the corneal stroma in a diffuse, multifocal pattern. Infiltration is confined to the surgical flap interface with no posterior or anterior extension, and overlying epithelium most often remains intact. As it is a sterile process, cultures based on swab tests are negative.
Stages
There are 4 stages of disease, with stage 4 being the rarest and most severe.
Stage 1 Cells infiltrate the periphery of the flap, without involving central cornea.
Stage 2 Peripheral cells migrate to the center of the cornea, and impair vision; presentation is usually 2 to 3 days after surgery.
Stage 3 Cells at the central cornea form clumps of dense cell aggregates.
Stage 4 Otherwise known as central toxic keratopathy, stage 4 characteristically has no inflammatory cells at the anterior chamber or cornea, but there is central stromal necrosis, and the cornea becomes opacified; onset is usually 3 to 9 days after refractive surgery.[8]
Treatment
Depending on severity, therapies may range from topical or oral anti-inflammatories to irrigation and surgical repair.
References
^Hagele, Glenn (2011-10-12). "Diffuse Lamellar Keratitis - DLK and Lasik, Bladeless Lasik, Sands of Sahara". Usaeyes.org. Retrieved 2013-01-10.
^Bielory, B. P.; oBrien, T. P. (2011). "Allergic complications with laser-assisted in-situ keratomileusis". Current Opinion in Allergy and Clinical Immunology11 (5): 483491. doi:10.1097/ACI.0b013e32834a4e01. PMID 21822133. edit
^Asano-Kato, N.; Toda, I.; Hori-Komai, Y.; Tsubota, K. (2001). "Allergic conjunctivitis as a risk factor for laser in situ keratomileusis". Journal of cataract and refractive surgery27 (9): 14691472. doi:10.1016/S0886-3350(01)00909-9. PMID 11566533. edit
^Faramarzi, A.; Feizi, S.; Javadi, M. A.; Rezaei Kanavi, M.; Yazdizadeh, F.; Moein, H. R. (2012). "Bilateral nocardia keratitis after photorefractive keratectomy". Journal of ophthalmic & vision research7 (2): 162166. PMC 3520474. PMID 23275825. edit
^Smith, R.; Maloney, R. K. (1998). "Diffuse lamellar keratitis a new syndrome in lamellar refractive surgery". Ophthalmology105 (9): 17211726. doi:10.1016/S0161-6420(98)99044-3. PMID 9754183. edit
^Morgan, L. A. (2012). "Central toxic keratopathy: A case study and literature review". Optometry (St. Louis, Mo.)83 (2): 7479. PMID 23231367. edit
We are Eva McElligott, Lila Farrag, and Teri Dombrowski. For our Physics 25 class with Professor Deardorff this semester, we had to select an area of technology and relate it to physics. Since we all have some sort of corrective eyeware, we decided to research something we'd all like to get done eventually--laser eye surgery!
Quick History:
Corrective eye surgery has been inpractice since the 1940s.Radialkeratotomy (RK) and photorefractive keratectomy (PRK) have had the greatestimpact on current methods of refractive eye surgery.The most common refractive surgery used todayis Laser in Situ Keratomileusis (LASIK).RK uses a diamond tipped knife to flatten the central cornea by making aseries of incisions radiating from the cornea.RK can only treat low degrees of myopia and astigmatism, unlikeLASIK.PRK uses a laser to correct therefractive area by removing corneal tissue.PRK can be discomforting or even painful because it removes nerve fibersthat run through the corneal epithelium.After this surgery, it can take up to six months for vision tostabilize.Immediately following thesurgery, vision is blurry until the corneal epithelium healed, and the bandagelens removed.PRK is similar to LASIKbecause it uses a laser to correct the corneal defects.LASIK has the same benefits, but with fewer,less-sever side effects than PRK.Also,LASIK is less painful, and recovery time is shortened because the cornealepithelium is not removed.The LASIKprocedure folds back the corneal epithelium and then a laser is used to reshapethe cornea.
The first lasers used were broad beamlasers (about 6 mm) that acted similar to a showerhead, splitting the mainlaser into smaller beams.Current lasertechnology implements the flying spot laser, named to describe the techniqueof creating a pattern with the laser, so that the full width of the flying spotbeam hits the cornea with each pulse.Advantages of this type of laser include a smoother corneal shape, andincreased accuracy and efficiency of the surgery.
Reference: Pictures taken from Bausch & Lomb http://www.bausch.com/us/vision/concerns/surgery/history.jsp
The Role of Physics in Laser Eye Surgery:
The deficiency of the eye can be examined using the physics of refraction.Refraction occurs mostly at the cornea due to the substantial difference between the index of refraction of the cornea, and that of air.The cornea and the lens combine to focus the light at the retina.The eye adjusts the curvature of the lens in order to alter the focal length, enabling it to focus objects at varying distances.A normal eye is able to converge light properly by changing the lens shape so that objects both near and far appear clearly.
In nearsightedness,the cornea is overly curved resulting in a greater index of refraction.The light converges, and the image forms infront of the retina.In order to correctthis problem with laser eye surgery the procedure begins with a surgeon temporarilypeeling back the epithelium.A laser isthen trained on the eye to remove small amounts of the cornea.The cornea is flattened in order to correctnearsightedness.The flattened corneahas a lower index of refraction than previously, focusing the image on theretina instead of in front of the retina.
Reference: Pictures taken from Physics at work http://kineticbooks.com/physics/17372/17405/sp.html
Another dysfunction of the eye is farsightedness.In farsightedness, the cornea is not curvedenough, and thus, the refractive index is lower.This causes the images focal point to belocated behind the retina.The surgeoncorrects this condition by using a laser to remove the outer edge of thecornea, thus steepening it.As a resultof this surgery, the eye is able to focus the image directly on the retina, dueto the greater index of refraction resulting from the curvature of the eyebeing increased.
Reference: Pictures taken from Physics at work http://kineticbooks.com/physics/17372/17405/sp.html
The type of laser used for these procedures is aultraviolet excimer laser, this type of laser usesand unstable inert gas with halogen, argon and fluorine to create an intense UVbeam.A list of approved lasers used forLASIK surgery is linked below.
http://www.lasikeyesurgery.com/approved-lasik.asp
Advantages, Disadvantages, and Risks:
Laser eye surgery is one of the fastest methods to correct visualimpairments. It has the ability to correct even severe refractive errors, butminimize the recovery time. Most patients are able to return to work within aweek! Many patients even return to normal activities the day after surgery. Thetreatment is permanent according to studies done so far, but as eyes changewith age re-treatment may be necessary over time. Eye drop medication isnecessary for the first week, but discomfort wears off after 5-6 hours. Themedication is used to prevent infection, not as a pain suppressant. The maindisadvantage of LASIK surgery is that it requires the creation ofa flap in thecornea. This step takes less than a minute to complete, but there are risks ofcomplications.
As with any surgery, there are risks associated with theprocedure. The best way to avoid certain risks is to have a thoroughexamination with your doctor pre-surgery. Some of these risks of surgeryinclude:
Corneal infection (less than 0.1% withLASIK)
Undercorrection/overcorrection
Decrease in best corrected vision
Corneal haze, though risk is less withLASIK than PRK
Regression, can be re-treated to correct
Halo effect in dim light
Flap damage or loss, when hinged part ofthe cornea is removed completely
Distorted flap when the corneal flap healsirregularly
What to Expect:
The first step tohaving laser eye surgery is a medical examination with your doctor to determineyour prescription, look for any retinal problems or unusual intraocularpressure, and look for signs of eye disease. A corneal topographer is used tomake a map of your cornea to help the surgeon determine how to correct theirregularities.Before you go in forsurgery, be sure to not wear any contact lenses for a week because that changesthe shape of the cornea. Also dont use makeup or lotions around the eyes.
During surgery,which lasts approximately 30 minutes, you will lie on your back and numbingdrops are placed in your eye. A lid speculum holds the eye open as it iscleaned and high pressures are applied to create suction around the cornea. Thedoctor uses a microkeratome, a blade, to cut a flapinto the cornea. Then the suction ring is removed. The flap is folded back anda laser positioned over your eye. The doctor will ask you to fixate on a pointof light, then use a laser to remove the cornealtissue. Pulses are heard as the computer programmed laser removes a fixedamount of tissue determined by pre-operation measurements. A shield is placedover the eye to prevent damage to the eye or movement of the flap, as nostitches are used. The pressure from the eye will cause the flap to resealagainst the eye and it will heal naturally.
After surgery,there may be slight discomfort, which can typically be removed by a mild overthe counter pain reliever. These symptoms should disappear within the first fewdays. A follow up appointment is absolutely necessary the day after surgery toensure the flap has not been dislodged and is in the appropriate place. After that, check-ups on regular intervals for only six months.Vision may fluctuate during the months after surgery but should stabilizewithin three to six months.
Who should get laser eye surgery?:
Laser eye surgery is ideal for anyone who wants the freedom thatimproved eyesight can give. The hassles of glasses and corrective lenses can beremoved, often permanently, by the procedure. But, laser eye surgery is not foreveryone. Before undergoing surgery, all patients should have a completemedical examination with their doctor. People with persistent medicalconditions, have difficulties healing, or have vascular, autoimmune, or eyediseases may notbesuitable for the procedure. Pregnant women should also refrain from surgery dueto changes in the eyes refraction during pregnancy.
Typical patientsfor eye surgery are at least over 18, though the age preference changes withthe type of laser used. Patients have mild to moderate nearsightedness,farsightedness, and astigmatisms, within the range of correction for thetreatment. Each laser has different ranges for the procedure performed.
Given the prolonged recovery of the economic environment, many companies and organizations have hunkered down to ride out the storm. Savvy industry leaders, however, are positioning for a new market and looking to conduct more effective and efficient business operations. These firms are recruiting and hiring candidates that have vision, proven performance and a broad business sense. Are you ready to demonstrate these skills?
The Executive MBA (EMBA) program at the UT Dallas Naveen Jindal School of Management offers the most robust curriculum in north Dallas with 53 credit hours. Our cohort approach encourages collaboration. Our leadership and our executive coaches work one-on-one with each EMBA student to improve soft skills and individualize our program to your specific needs. We also offer two trips an Americas trip and an international trip.
The UT Dallas Executive MBA program is relevant, engaging and transformational. Join us for an Information Session soon to learn how we can help you prepare for 2025.
Pamela Foster Brady Director, Executive MBA Program
Email
(972) 883-4235
Office JSOM 1.905
The Executive MBA program at UT Dallas, Naveen Jindal School of Management is designed to enable business professionals to maximize their business performance.
Our 21-month cohort program, over 5 semesters, begins in August each year. (View the 2016 calendar).
Classes generally meet 3-4 times each month. Students meet all day Friday and Saturday and then have a weekend off. On the third weekend, students meet all day Friday and Saturday or just Saturday.
Classes run from 8 a.m. to 5 p.m. Lunch is served on campus from noon to 1 p.m.
Students take two study tours. Our Americas trip enables a better understanding of government policy. In recent years we have been to Toronto, CA, Vancouver, CA, Washington, D.C. and most recently, Panama City, Panama. The Class of 2016 will be going to Nova Scotia. Our international trip compares how business is conducted and how cultures vary in two different cities/countries. Our recent trips have been to Hong Kong and Shanghai, China, Delhi and Mumbai, India and Taipei, Taiwan and Beijing, China. The Class of 2014 went to Melbourne, Canberra, and Sydney, Australia.
Professors engage business executives to participate in the class environment throughout the program.
We offer a structured Executive Coaching program to help you refine your executive presence, social networking skills and political and social intelligence
The business world is becoming increasingly dynamic with globalization and information/mobile technologies changing how the world does business. Change in the economic environment mandates that companies must be more efficient and effective even as Big Data analytics fundamentally changes how people manage and forecast business trends. Social networks increasingly impact consumers buying trends and customer relationships. For the first time ever, we have four distinct generations in the workplace. Yet, at the end of the day, its all about leading and motivating people.
After meeting with numerous professors, alumni and business partners, we have refreshed our curriculum to be forward thinking. We aim to prepare business professionals to develop and implement successful strategies for today, 2025 and beyond.
Our curriculum still includes the fundamentals of business such as organizational behavior, financial accounting, managerial accounting, financial management, business economics and marketing. But its emphasis now addresses questions such as:
How and where does your company deploy its corporate resources and assets? What is the best strategy to move forward?
In a near real-time, data-driven business environment, what data do you really need to connect with existing customers, drive new business, and forecast new trends? How will you interpret and use this data?
What does leadership mean in a globalized economy? How to does a company develop a public image that recognizes international cultures and assumes corporate social responsibility and still increases shareholder wealth?
A snapshot of our program by semester is below. The numbers in the italics are the number of credit hours.
Semester 1 Fall 2014
Semester 2 Spring 2015
Semester 3 Summer 2015
Semester 4 Fall 2015
Semester 5 Spring 2016
Business Economics (3)
Organizational Behavior (3)
Operations Management (3)
Global Strategy (3)
Global Economics (2)
Marketing (3) Financial Accounting (2)
Business, Management, Analytics and Technology (3)
Financial Management (3)
C-Suite Leadership (2)
Negotiations and Contracts (3)
Board Membership, Risk Management, and Compliance (2)
Statistics and Probability (3)
Promoting Innovation (3)
Creating Value thru M&As and Private Equity (2)
Field Project (2)
Managerial Accounting (2)
Enterprise Transformation (2)
International Business Management (2)
Americas Trip (1)
Coaching (1)
International Trip (3)
In addition to the course work above, all students must work with an ICF-certified Executive Coach to address their soft skills. Our curriculum also includes two study trips. With our program accredited at 53 credit hours, we offer the most robust curriculum in North Texas.
The Naveen Jindal School of Management reserves the right to change any of the above course, structure or cost of the program at any time, as needed.
The UT Dallas Executive MBA program offers two study trips: the Americas trip in the second semester and the international trip in the final semester.
Americas Trip
Our first year Americas trip is a four-day trip designed to enable a better understanding of business and government policy. In recent years, we have been to Toronto, Canada, Vancouver, Canada, and Washington, D.C. The Class of 2015 visited Panama in March 2014 and the Class of 2016 will go to Nova Scotia in 2015.
International Trip
Our second year 10-day international trip is designed to enable EMBA students to meet with business and government executives and educators to better understand the dynamic global business environment and culture of two different cities, often in two separate countries.
Our recent trips have been to Hong Kong and Shanghai, China; Delhi and Mumbai, India; Taipei, Taiwan and Beijing, China. The Class of 2014 visited Melbourne and Sydney Australia in April 2014. We will announce the international study tour location for the Class of 2015 in August 2014.
Costs of the trips are included in the tuition costs with the exception of the long flight for the international trip. This gives students the flexibility to use their frequent flyer miles and to travel independently before or after the trip.
In your first semester of the Executive MBA program you will be assigned an executive coach. Our coaches have been selected by Dr. Robert Hicks, director of the Organizational Behavior and Coaching Program at UT Dallas. All are certified by the International Coaching Federation (ICF).
You will begin the program with a Winslow Profile to assess your strengths and weaknesses. Working with your coach, you will develop a professional development plan to focus on developing five executive core competencies, including:
Strategic self-awareness
Social intelligence
Political intelligence
Executive presence
Social networking
Each month, you will complete homework assignments designed to help reach your personal and professional growth goals.
One of the many benefits of the UT Dallas executive MBA program was the opportunity to build my skills with an experienced, proven leader my personal coach. My executive coach was invaluable during my interview process and during my first year in my new position.
The UT Dallas Executive MBA offers you the best value per credit hour in the north Texas region. Our 53 credit hour program is the most robust in the region. Our program includes two trips (exclusive of the international airfare) and a structured executive coaching in addition to an engaging, relevant and quality educational experience.
The total investment for the Executive MBA program for the August 2014 seating (Class of 2016) is $82,000 and includes:
Tuition
Books
Fees
Executive coaching
Parking permits
Two study trips
Meals on class days
The cost is paid in five equal installments due prior to the start of each semester.
See also: Aberration in optical systems and Astigmatism (eye)
v
t
e
Optical aberration
Distortion
Spherical aberration Coma Astigmatism Petzval field curvature Chromatic aberration Defocus Tilt
An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances. The term comes from the Greek - (a-) meaning "without" and (stigma), "a mark, spot, puncture".[1]
Forms of astigmatism
Astigmatism
There are two distinct forms of astigmatism. The first is a third-order aberration, which occurs for objects (or parts of objects) away from the optical axis. This form of aberration occurs even when the optical system is perfectly symmetrical. This is often referred to as a "monochromatic aberration", because it occurs even for light of a single wavelength. This terminology may be misleading, however, as the amount of aberration can vary strongly with wavelength in an optical system.
The second form of astigmatism occurs when the optical system is not symmetric about the optical axis. This may be by design (as in the case of a cylindrical lens), or due to manufacturing error in the surfaces of the components or misalignment of the components. In this case, astigmatism is observed even for rays from on-axis object points. This form of astigmatism is extremely important in vision science and eye care, since the human eye often exhibits this aberration due to imperfections in the shape of the cornea or the lens.
Third-order astigmatism
Page explaining and illustrating astigmatism[2]
In the analysis of this form of astigmatism, it is most common to consider rays from a given point on the object, which propagate in two special planes. The first plane is the tangential plane. This is the plane which includes both the object point being considered and the axis of symmetry. Rays that propagate in this plane are called tangential rays. Planes that include the optical axis are meridional planes. It is common to simplify problems in radially-symmetric optical systems by choosing object points in the vertical ("y") plane only. This plane is then sometimes referred to as the meridional plane.
The second special plane is the sagittal plane. This is defined as the plane, orthogonal to the tangential plane, which contains the object point being considered and intersects the optical axis at the entrance pupil of the optical system. This plane contains the chief ray, but does not contain the optic axis. It is therefore a skew plane, in other words not a meridional plane. Rays propagating in this plane are called sagittal rays.
In third-order astigmatism, the sagittal and transverse rays form foci at different distances along the optic axis. These foci are called the sagittal focus and the transverse focus, respectively. In the presence of astigmatism, an off-axis point on the object is not sharply imaged by the optical system. Instead, sharp lines are formed at the sagittal and transverse foci. The image at the transverse focus is a short line, oriented in the direction of the sagittal plane; images of circles centered on the optic axis, or lines tangential to such circles, will be sharp in this plane. The image at the sagittal focus is a short line, oriented in the tangential direction; images of spokes radiating from the center are sharp at this focus. In between these two foci, a round but "blurry" image is formed. This is called the medial focus or circle of least confusion. This plane often represents the best compromise image location in a system with astigmatism.
The amount of aberration due to astigmatism is proportional to the square of the angle between the rays from the object and the optical axis of the system. With care, an optical system can be designed to reduce or eliminate astigmatism. Such systems are called anastigmats.
Astigmatism in systems that are not rotationally symmetric
Blur from astigmatic lens at different distances.
If an optical system is not axisymmetric, either due to an error in the shape of the optical surfaces or due to misalignment of the components, astigmatism can occur even for on-axis object points. This effect is often used deliberately in complex optical systems, especially certain types of telescope.
In the analysis of these systems, it is common to consider tangential rays (as defined above), and rays in a meridional plane (a plane containing the optic axis) perpendicular to the tangential plane. This plane is called either the sagittal meridional plane or, confusingly, just the sagittal plane.
Ophthalmic astigmatism
Main article: Astigmatism (eye)
In optometry and ophthalmology, the vertical and horizontal planes are identified as tangential and sagittal meridians, respectively. Ophthalmic astigmatism is a refraction error of the eye in which there is a difference in degree of refraction in different meridians. It is typically characterized by an aspherical, non-figure of revolution cornea in which the corneal profile slope and refractive power in one meridian is less than that of the perpendicular axis.
Astigmatism causes difficulties in seeing fine detail. Astigmatism can be often corrected by glasses with a lens that has different radii of curvature in different planes (a cylindrical lens), contact lenses, or refractive surgery.[3]
Astigmatism is quite common. Studies have shown that about one in three people suffers from it.[4][5][6] The prevalence of astigmatism increases with age.[7] Although a person may not notice mild astigmatism, higher amounts of astigmatism may cause blurry vision, squinting, asthenopia, fatigue, or headaches.[8][9][10]
There are a number of tests that are used by ophthalmologists and optometrists during eye examinations to determine the presence of astigmatism and to quantify the amount and axis of the astigmatism.[11] A Snellen chart or other eye chart may initially reveal reduced visual acuity. A keratometer may be used to measure the curvature of the steepest and flattest meridians in the cornea's front surface.[12]Corneal topography may also be used to obtain a more accurate representation of the cornea's shape.[13] An autorefractor or retinoscopy may provide an objective estimate of the eye's refractive error and the use of Jackson cross cylinders in a phoropter may be used to subjectively refine those measurements.[14][15][16] An alternative technique with the phoropter requires the use of a "clock dial" or "sunburst" chart to determine the astigmatic axis and power.[17][18]
Astigmatism may be corrected with eyeglasses, contact lenses, or refractive surgery. The planning and analysis of astigmatism treatment in corneal, cataract, and refractive surgery has been outlined by the American National Standards Institute, and was originally described by Australian ophthalmologist Noel A. Alpins in his Alpins Method of astigmatism analysis. Various considerations involving ocular health, refractive status, and lifestyle frequently determine whether one option may be better than another. In those with keratoconus, toric contact lenses often enable patients to achieve better visual acuities than eyeglasses. If the astigmatism is caused by a problem such as deformation of the eyeball due to a chalazion, treating the underlying cause will resolve the astigmatism.
Misaligned or malformed lenses and mirrors
Grinding and polishing of precision optical parts, either by hand or machine, typically employs significant downward pressure, which in turn creates significant frictional side pressures during polishing strokes that can combine to locally flex and distort the parts. These distortions generally do not possess figure-of-revolution symmetry and are thus astigmatic, and slowly become permanently polished into the surface if the problems causing the distortion are not corrected. Astigmatic, distorted surfaces potentially introduce serious degradations in optical system performance.
Surface distortion due to grinding or polishing increases with the aspect ratio of the part (diameter to thickness ratio). To a first order, glass strength increases as the cube of the thickness. Thick lenses at 4:1 to 6:1 aspect ratios will flex much less than high aspect ratio parts, such as optical windows, which can have aspect ratios of 15:1 or higher. The combination of surface or wavefront error precision requirements and part aspect ratio drives the degree of back support uniformity required, especially during the higher down pressures and side forces during polishing. Optical working typically involves a degree of randomness that helps greatly in preserving figure-of-revolution surfaces, provided the part is not flexing during the grind/polish process.
Deliberate astigmatism in optical systems
Compact disc players use an astigmatic lens for focusing. When one axis is more in focus than the other, dot-like features on the disc project to oval shapes. The orientation of the oval indicates which axis is more in focus, and thus which direction the lens needs to move. A square arrangement of only four sensors can observe this bias and use it to bring the read lens to best focus, without being fooled by oblong pits or other features on the disc surface.
Some telescopes use deliberately astigmatic optics.[19]
See also
Anastigmat (lens type)
Stigmatism
References
^Harper, Douglas (2001). "Online Etymology Dictionary". Retrieved 2007-12-29.
^Frederic Eugene Wright (1911). The Methods of Petrographic-microscopic Research, Their Relative Accuracy and Range of Application. Carnegie institution of Washington.
^"Astigmatism Laser Eye Surgery". The Irish Times.
^Kleinstein RN, Jones LA, Hullett S, Kwon S, et al. (2003). "Refractive Error and Ethnicity in Children". Arch Ophthalmol.121 (8): 11417. doi:10.1001/archopht.121.8.1141. PMID 12912692.
^Garcia CA, Oréfice F, Nobre GF, Souza Dde B, Rocha ML, Vianna RN (2005). "[Prevalence of refractive errors in students in Northeastern Brazil.]". Arq Bras Oftalmol (in Portuguese) 68 (3): 3215. doi:10.1590/S0004-27492005000300009. PMID 16059562.
^Bourne RR, Dineen BP, Ali SM, Noorul Huq DM, Johnson GJ (June 2004). "Prevalence of refractive error in Bangladeshi adults: results of the National Blindness and Low Vision Survey of Bangladesh". Ophthalmology111 (6): 115060. doi:10.1016/j.ophtha.2003.09.046. PMID 15177965.
^Asano K, Nomura H, Iwano M, et al. (2005). "Relationship between astigmatism and aging in middle-aged and elderly Japanese". Jpn. J. Ophthalmol.49 (2): 12733. doi:10.1007/s10384-004-0152-1. PMID 15838729.
^Eyetopics.com
^Medicinenet.com
^Hipusa.com
^Hipusa.com
^Stlukeseye.com
^Emedicine.com
^Graff T (June 1962). "[Control of the determination of astigmatism with the Jackson cross cylinder.]". Klin Monatsblatter Augenheilkd Augenarztl Fortbild (in German) 140: 7028. PMID 13900989.
^Del Priore LV, Guyton DL (November 1986). "The Jackson cross cylinder. A reappraisal". Ophthalmology93 (11): 14615. PMID 3808608.
^Brookman KE (May 1993). "The Jackson crossed cylinder: historical perspective". J Am Optom Assoc64 (5): 32931. PMID 8320415.
^Quantumoptical.com
^Nova.edu
^Sacek, Vladimir (July 14, 2006). "Telescope astigmatism". Amateur Telescope Optics. Archived from the original on 19 September 2008. Retrieved Oct 16, 2008.
Greivenkamp, John E. (2004). Field Guide to Geometrical Optics. SPIE Field Guides vol. FG01. SPIE. ISBN 0-8194-5294-7.
Hecht, Eugene (1987). Optics (2nd ed.). Addison Wesley. ISBN 0-201-11609-X.
Using LASIK To Treat Dallas, Plano, Fort Worth and Arlington Patients
Blade-Free HD IntraLASIK at Kleiman|Evangelista Eye Center is one of the most accurate and customizable procedures available today for vision correction. The all-laser technology is designed specifically to improve outcomes for Dallas LASIK, Fort Worth LASIK, Arlington LASIK and surrounding area patients!
Whether you have nearsightedness, farsightedness or astigmatism, your cornea (the surface of your eye) is not focusing light appropriately onto your retina. This causes blurred vision. Our surgeons use LASIK to reshape the corneal surface, correcting the focal point of your cornea so you can see clearly.
Understanding the LASIK Procedure
Understanding the 2 steps of the LASIK procedure can help to realize the benefits of the all-laser Blade-Free HD IntraLASIK procedure. During Step 1a (shown above), a corneal flap is created, and in Step 1b, the corneal flap is lifted up. In Step 2 your surgeon reshapes the corneal surface and the procedure ends (2b) with the corneal flap positioned back into place.
In the first step, your surgeon will use the iFS laser, a femtosecond laser, to generate a thin flap in the corneal surface of your eye. In the past, surgeons have used blades called microkeratomes to make this flap. While results of LASIK with microkeratomes were often good, it still left the opportunity for a margin of error.
Your Kleiman|Evangelista Eye Center surgeon will use the IntraLase iFS to complete this step, which adds microscopic accuracy to the LASIK procedure.
The IntraLase iFS is a cool laser light that produces a layer of micron-bubbles to a pre-established depth in your cornea (part of the customization of the procedure). These tiny bubbles work to gently separate the corneal flap from the eyes surface.
With the IntraLaser iFS laser, your surgeon can pre-program the depth of the laser to create a consistent flap, which can serve to reduce potential issues that are related to traditional LASIK with a microkeratome.
The precision of the IntraLase iFS means more people are candidates for Kleiman|Evangelista Eye Center compared to LASIK with a blade, particularly those with corneas that are too thin for traditional LASIK.
During the second step of Blade-Free HD IntraLASIK, your physician uses the ViSX CustomVue Star S4 laser to reshape the corneal surface.
Remember when we talked about your vision being blurry because the cornea isnt focusing light properly onto your retina? Your surgeon uses the ViSX lasers micron precision to slightly adjust the surface of the cornea in order to help it focus light accurately onto the retina.
Once this step is complete, the corneal flap is put back into place (Step 2b) and self-seals.
Blade-Free HD IntraLASIK generally offers a rapid visual recovery. Many patients are able to achieve notably improved vision the day following their procedures, and they often report their eyes feel close to normal within a day. Typically, vision continues to improve in following days and weeks.
Patients can resume most daily activities virtually immediately following the LASIK procedure.
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Schedule Your LASIK Evaluation | Or Call Our Patient Counselors at 1-800-714-2020.
At the Laser Center for Vision Care, UT Southwesterns nationally recognized ophthalmologists have one goal: improve patients quality of life by helping them see better without glasses or contacts. LASIK is just one area of expertise, part of a comprehensive program of vision care designed to preserve healthy eyesight and prevent blindness.
Individualized Care
From exam to surgery to follow-up, one doctor will personally take care of your eyes. At the UT Southwestern Laser Center, you will never feel like you're part of an assembly line.
Our Specialists
Our doctors are nationally recognized leaders in eye care advancements. We've published more outcomes about LASIK surgery than any other eye specialists in North Texas, participated in trials to evaluate procedures and technology, and taught other doctors about the surgery.
Our Treatments
Our customized treatments vary from all-laser IntraLase custom LASIK to the newest refractive intraocular lenses (IOLs) and beyond. Our experienced surgeons make certain you receive the most thorough and highest quality care available.
Comprehensive Care
UT Southwestern's Laser Center for Vision Care is one of the most accomplished and comprehensive vision care facilities in the world. Our nationally recognized physicians employ state-of-the-art technologies combined with the highest possible standards in medicine to ensure that your LASIK experience is nothing short of first class. When it comes to your eye health, you should never settle for anything but the best.
All our prices are inclusive, covering the entirety of your care up to one year after surgery.
We are a team of renowned optometrists and ophthalmologists serving patients in need throughout Arlington and Mansfield, Texas. Our mission is to maintain and, in most cases, improve our patient's vision health so that they can live a fulfilling and healthy lifestyle.
Welcome to Ford Eye Center
Now you can have Blade Free Cataract eye surgery
Blade Free Cataract Surgery
See better after cataract surgery with the new lifestyle lens options! Lifestyle lenses allow you to see both near and far distances and can decrease your dependence on eye glasses after surgery. If you are seeking experienced cataract surgeons in the DFW area, call us today!
Lifestyle Lens Options
Ford Eye Center strives to help making the financial aspects of LASIK eye surgery and other elective eye surgeries affordable for our patients. Some vision correction procedures are not covered by health insurance and because of this; we offer financing that will enable you to have the eye surgery you need.
Even if you have lived in Dallas TX for a long time, a lasik surgeon is not something you need every day. Which makes it even more vital to find a reliable lasik doctor to perform your lasik eye surgery, this is not something you want to leave to chance. Our list for Dallas TX will give you an excellent place to start your search for the best lasik surgeons in Dallas TX without having to do hours of research.
Our listings are carefully maintained to ensure positive experiences for our users as best as we can. We want to make sure that your laser eye surgery is a good experience for you so make sure you check with a couple of the lasik surgeons listed in Dallas TX to find which one you are most comfortable with and who will be the perfect surgeon for you.
Welcome to Gaston Eye Associates where we believe in providing our patients with thorough eye health care. Because we know how much your eye health and appearance can mean to the quality of your life, we are committed to excellence in servicing your complete eye care needs gastonia eye care
The Trusted LASIK Surgeons directory only lists surgeons who have extensive qualifications and experience. We estimate these Dallas - Fort Worth based LASIK, refractive, and cataract surgery eye doctors are among the top 1% performing vision correction in the United States.
Dallas-Fort Worth LASIK Surgeon James McCulley, MD
James P. McCulley, M.D., is Professor and Chair of the Department of Ophthalmology at UT Southwestern Medical Center in Dallas. His extensive qualifications place him among the top 1% of refractive and cataract surgeons in the U.S. Dr. McCulleys exceptional qualifications are listed via the link above.
For more information, please contact the UT Southwestern Laser Center for Vision Care at 888-663-2020, or laservision@utsouthwestern.edu. You can also learn more at utswlasik.com.
Dallas-Fort Worth LASIK Surgeon R. Wayne Bowman, MD
Also at the University of Texas, Southwestern Medical Center in Dallas, Dr. R. Wayne Bowman's has extensive qualifications and experience that Trusted LASIK Surgeons estimates place him among the top 1% of LASIK, laser eye surgery, cataract surgery and refractive surgeons in the United States.
Doctors McCulley and Bowman have offices serving the Dallas, Fort Worth metroplex, Richardson, Plano, Arlington, Duncanville & Highland Park areas.
UT Southwestern Laser Center for Vision Care Department of Ophthalmology 1801 Inwood Road Dallas, TX 75390-8895
Phone: 888-663-2020
Call today for your consultation with a true LASIK Laser eye expert who is a trusted eye surgeon and vision correction surgery specialist.
We invite you to review our qualification process, each surgeon's profile, and select your LASIK surgeon with confidence.
When you select a surgeon from the Trusted LASIK Surgeons directory, you will meet with a true LASIK Eye Surgery expert who is a trusted eye surgeon and vision correction surgery specialist. You will gain the advice, wisdom, and expertise of a profoundly qualified refractive eye surgeon at an exceptional value.
LASIK surgery is the most technologically advanced method for correcting nearsightedness, astigmatism, and farsightedness. More than a million LASIK procedures have been performed in the United States, and the safety and effectiveness of the surgery is now unquestionable. Dr. Michael Mazaheri can perform the procedure at his office, serving patients from throughout the DFW Metroplex, including Richardson and Dallas area LASIK patients, in approximately fifteen minutes and for most patients the entire LASIK surgery will be painless, quick, and easy.
The LASIK Surgery Procedure LASIK Surgery Benefits LASIK Surgery Risks LASIK Surgery Testimonials
The LASIK Surgery Procedure
The M LASIK Center is conveniently located in Richardson and serves patients throughout the Dallas Fort Worth Metroplex. The LASIK procedure at our center is performed with the patient's utmost safety and comfort in mind. Dr. Mazaheri offers the most advanced and precise technology, including Wavefront guided LASIK, and Intralase® bladeless LASIK to help his patients achieve superior vision correction results.
Prior to surgery, eye drops are administered to numb the eye and ensure maximum comfort throughout your LASIK procedure. A device is positioned to prevent blinking during LASIK surgery, and then the corneal flap is created using either a microkeratome or the Intralase® laser. Dr. Mazaheri carefully folds back the flap, exposing the inner layer of the cornea, and uses an excimer laser to reshape the area according to the patient's unique vision correction needs.
Generally, the laser is applied to each eye for less than one minute. The corneal flap is then folded back into place, where it adheres to the eye naturally and securely. During the LASIK procedure, Dr. Mazaheri will explain each step, from start to finish, and will make you as comfortable as possible. At our Richardson and Dallas area office, LASIK patients are often able to see the change in their vision just a few hours after surgery.
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LASIK Surgery Benefits
Thanks to Dr. Mazaheri's exceptional training and skill, residents in Richardson and Dallas, and LASIK patients throughout the DFW Metroplex can enjoy safe, superior vision correction results. The vast majority of LASIK patients at our office experience a quick recovery with minimal downtime and benefit from a reduced or eliminated need for glasses or contact lenses. In addition, many LASIK patients also enjoy enhanced quality of vision after their surgery, resulting in vision that is sharp and clear.
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LASIK Surgery Risks
Patients in the Dallas area who undergo LASIK surgery at The M LASIK Center can expect few or no complications and significant improvement in vision after surgery. However, all surgery does carry some risk, so Dr. Mazaheri works with each patient to determine individual needs with thorough pre-operative testing. He develops a customized treatment plan to minimize the risk of complications like halos, contrast sensitivity, under-correction, and over-correction.
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Testimonials About Our Richardson and Dallas Area LASIK Center
A prominent physician serving the DFW Metroplex, including the Richardson and Dallas areas, LASIK surgeon Michael Mazaheri, M.D., has helped many satisfied patients enjoy the convenience of improved vision. A number of other doctors have even entrusted their sight to Dr. Mazaheri and have referred their family and patients to him as well. Their laser eye surgery testimonials convey Dr. Mazaheri's reputation for superior care.
If you live in Richardson or anywhere in the Dallas Fort Worth Metroplex and you would like to learn more about LASIK surgery, please contact our LASIK surgery center today!
The Trusted LASIK Surgeons directory only lists surgeons who have extensive qualifications and experience. We estimate these Dallas-based LASIK, refractive, and cataract surgery eye doctors are among the top 1% performing vision correction in the United States.
Dallas LASIK Surgeon James McCulley, MD
Dr. James McCulley, M.D., in Dallas, TX, has extensive qualifications that Trusted LASIK Surgeons estimates place him among the top 1% of LASIK, laser eye surgery, refractive surgeons & cataract surgeons in the USA. Dr. McCulley's exceptional qualifications are listed via the link above.
For more information, please contact the UT Southwestern Laser Center for Vision Care at 888-663-2020, or laservision@utsouthwestern.edu. You can also learn more at utswlasik.com.
Dallas LASIK Surgeon R. Wayne Bowman, MD
Also at the University of Texas, Southwestern Medical Center in Dallas, Dr. R. Wayne Bowman's has extensive qualifications and experience that Trusted LASIK Surgeons estimates place him among the top 1% of LASIK, laser eye surgery, cataract surgery and refractive surgeons in the United States.
Doctors McCulley and Bowman have offices serving the Dallas, Fort Worth metroplex, Richardson, Plano, Arlington, Duncanville & Highland Park areas.
UT Southwestern Laser Center for Vision Care Department of Ophthalmology 1801 Inwood Road Dallas, TX 75390-8895
Phone: 888-663-2020
Dallas LASIK and Cataract Surgeon Dr. Robert Smith
Dr. Robert E. Smith, II treats patients seeking LASIK, refractive and cataract surgery from Plano, Dallas, Addison, and Fort Worth and throughout Texas
LasikPlus-Plano/Dallas Polo Towne Crossing 2108 Dallas Parkway Suite 206 Plano, Texas 75093
(866) 755-2026 Phone (Español): (866) 921-2394
Call today for your consultation with a true LASIK Laser eye expert who is a trusted eye surgeon and vision correction surgery specialist.
We invite you to review our qualification process, each surgeon's profile, and select your LASIK surgeon with confidence.
When you select a surgeon from the Trusted LASIK Surgeons directory, you will meet with a true LASIK Eye Surgery expert who is a trusted eye surgeon and vision correction surgery specialist. You will gain the advice, wisdom, and expertise of a profoundly qualified refractive eye surgeon at an exceptional value.
Give us a call today at 888-215-1999. Phones are answered Monday - Friday, 7:45 AM - 9:00 PM and Saturday and Sundays, 11:00 AM - 5:00 PM. Hours of Operation: Monday - Friday, 8:00AM - 5:00PM.
We now offer FREE VALET at our Dallas location! FREE Valet service offered from 9:00AM - 3:00PM. We also offer free WIFI and TV to entertain our patients.
Doctors at the Dallas location include Jeffrey Whitman, M.D., Todd J. Agnew, O.D., Jorge Corona, M.D., Pat Colerick, O.D., and Tom Jennings, M.D.
CustomVue laser vision correction is an exciting, new procedure that incorporates WaveScan wavefront technology and the patented, FDA-approved VISX laser to create a highly effective, personalized treatment plan for patients. Without custom LASIK, doctors must rely on one-size-fits-all, traditional laser vision correction, which achieves great results but is not nearly as precise as CustomVue. In fact, our practice in Dallas, Texas can achieve custom LASIK results that are up to 25 times more accurate than traditional LASIK!
<Learn More About Types of LASIK
It is entirely normal to be anxious about having LASIK surgery. Certainly, having laser eye surgery is an unusual experience, but we do our best to make LASIK surgery quick and painless. Let us walk you through a typical LASIK eye surgery procedure, as performed at Cornea Associates of Texas.
<Learn More About What to Expect When You Have LASIK Eye Surgery
At Cornea Associates of Texas, we pride ourselves in providing the highest quality of LASIK care. Quality begins with a professional and caring attitude. It extends to thoroughness and accuracy of data collection in preparation for surgery. It involves well-trained, skilled surgeons and certified surgical support staff uniquely qualified to perform your eye surgery. It means using state-of-the-art laser equipment. It is enhanced by the comfort of a first class facility.
<Learn More About Why Choose Us
We are proud to share the results following LASIK achieved by the doctors at Cornea Associates of Texas. This analysis is based on a retrospective review of 200 eyes with a minimum of 2 months follow up. All patients underwent Wavefront guided LASIK using the VISX Star S4 with Iris Registration technology. <Learn More About Statistics on LASIK
PRK is performed using the same excimer laser technology as LASIK. In both PRK and LASIK, the excimer laser removes a precise amount of corneal tissue in order to refocus images and provide clear vision. The primary difference between PRK and LASIK is the location on the eye where the laser treatment is applied. In LASIK, a flap is made in the cornea first and then the treatment is applied under that flap. In PRK, no flap is made, the treatment is simply applied to the surface of the eye. A consultation will help to determine which procedure is best for your eyes.
<Learn More About PRK
Cornea Associates of Texas utilizes highly advanced technology to perform your laser vision correction procedure. Combining the IntralaseIFS Femtosecond Laser, the VISX Star S4 Excimer Laser, and Wavescan technology, we are able to provide the majority of our patients with visual outcomes better than 20/20. The Wavescan technology captures a personalized map and produces measurements 25 times more precise than standard refractive error measurements. The Wavescan map is used to guide the VISX Star S4 during the actual treatment, resulting in incredibly accurate results.
Distortion
Spherical aberration
Coma
Astigmatism
Petzval field curvature
Chromatic aberration
Defocus
Tilt
Key-Whitman Eye Center - The LASIK Center in Dallas
