Refractive surgical procedures. Medical search. Frequent questions

The discovery of an effective biological cutting laser, along with the development of computers to control it, enabled the development of new refractive surgery techniques. (wikipedia.org)

This can include various methods of surgical remodeling of the cornea (keratomileusis), lens implantation or lens replacement. (wikipedia.org)
RK involves making a number of cuts in the cornea to change its shape and correct refractive errors. (wikipedia.org)
The procedure involves producing a flap in the cornea and also making use of a laser to improve the cornea. (xtgem.com)
The procedure resulted in an uneven application of heat, with the external cornea receiving more heat than the inner cornea. (medscape.com)
They followed principles formulated by Krumeich using a microkeratome to remove a portion of the cornea followed by a second plano cut, the thickness and diameter of which established refractive change. (medscape.com)
The refractive error can often be corrected by changing the shape of the cornea. (ucihealth.org)
The cornea is transparent, and provides the major refractive power for producing a focused image on the retina. (molvis.org)
Among the myopic adult Egyptian population, the greater the myopic error measured, the steeper the cornea, with a weak positive correlation between refractive error and corneal power. (dovepress.com)
At Khanna Vision Institute, Dr. Rajesh Khanna, Medical Director offers services like Painless Lasik, Superlasik, EVO ICL, SuperLasik, PIE Procedure (Presbyopic Implant in Eye), Laser Cataract Surgery, Cornea Cross Linking For Keratoconus and Cosmetic Pterygium Treatments and more. (khannainstitute.com)
A procedure called orthokeratology has been available for many years, where a series of progressively flatter gas permeable hard contact lenses are used to gently and gradually re-shape the surface of the cornea. (atlanta2020.com)
Like LASIK, PRK is a refractive surgical procedure which uses a laser to reshape the cornea. (visionboston.com)
If your cornea or lens isn't evenly and smoothly curved, light rays aren't refracted properly, and you have a refractive error. (middlesexhealth.org)
Laser refractive surgery refers to all the surgical procedures on the cornea that correct for near-sightedness (myopia), far-sightedness (hyperopia), and astigmatism prescriptions. (sve.com)
LASIK is a procedure that reshapes the shape of the cornea and corrects your vision. (goldberg4lasik.com)
He is an active member of the Georgia Optometric Association, the American Academy of Optometry and the Optometric Cornea, Cataract and Refractive Society. (thomaseye.com)
These procedures are commonly used to reshape the cornea so that it is better able to focus light on the retina. (msdmanuals.com)
Eyeglasses Refractive errors can be corrected with glass or plastic lenses mounted in a frame (eyeglasses) or with a small lens made of plastic floating or resting on the cornea (contact lens). (msdmanuals.com)
METHODS: Corneal transplant procedures registered in the European Cornea and Cell Transplantation Registry were identified. (lu.se)
The total refractive power of an emmetropic (or normal length) eye is approximately 58 diopters (D), of which 43 D come from the cornea and the remaining 15 D from the lens, aqueous, and vitreous. (medscape.com)

Refractive eye surgeries are used to treat common vision disorders such as myopia, hyperopia, presbyopia and astigmatism. (wikipedia.org)
Astigmatism is a refractive error that can be remedied by get in touch with lenses, glasses, or laser eye surgery. (xtgem.com)
It can deal with one of the most typical refractive errors, including nearsightedness (nearsightedness), farsightedness (hyperopia), as well as astigmatism. (xtgem.com)
Concepts of corneal refractive surgery, such as keratectomy, keratotomy, and thermokeratoplasty, were first described in 1898 by Lans who published a set of experiments that focused on treating astigmatism in rabbits. (medscape.com)
Newer flapless refractive surgical procedures, such as SMILE can correct myopia or astigmatism by extracting a tiny lenticule from each eye of the patient using a femtosecond laser. (asiaone.com)
The PRK procedure is an especially good fit for people with mild to moderate nearsightedness, farsightedness, and/or astigmatism. (visionboston.com)
LASIK, or laser in-situ keratomileusis, is a sort of refractive surgery that is developed to deal with typical vision problems, such as myopia, hyperopia, as well as astigmatism. (zagran-pasport.info)
With the latest advances in laser refractive surgery, there are several treatments to correct refractive eye conditions, such as nearsightedness, farsightedness and astigmatism. (ucsfhealth.org)

Hamed AM, Wang L, Misra M, Koch DD " A comparative analysis of five methods of determining corneal refractive power in eyes that have undergone myopic laser in situ keratomileusis. . (bcm.edu)
Laser in situ keratomileusis (LASIK), since its introduction by Pallikaris and his team in 1990, 1 has become the most frequently performed corneal refractive procedure all over the world, with millions of LASIK procedures completed to date. (dovepress.com)
Treatments include eyeglasses, contact lenses, corneal refractive therapy laser procedures, or surgery (in extreme cases). (medicalnewstoday.com)

People in this age range often think they are not candidates for refractive surgery, but in fact many are excellent candidates for a premium IOL. (crstodayeurope.com)
The best candidates for refractive surgery are healthy people aged 18 and older with healthy eyes who are not satisfied with eyeglasses or contact lenses and who enjoy activities, such as swimming or skiing, which are difficult to do with eyeglasses or contact lenses. (msdmanuals.com)

Dr. Shapiro has addressed international congresses of refractive surgery and has been invited to speak on refractive surgery to the American Academy of Ophthalmology. (jurispro.com)

My work focuses on improving the outcomes of cataract surgery and refractive surgery procedures such as LASIK and PRK. (bcm.edu)
Technological innovation continues to refine cataract surgery and refractive lens exchange to provide increasingly successful and customized outcomes. (crstoday.com)

Another type of refractive surgery for people who have severe nearsightedness involves insertion of a thin lens inside the eye. (msdmanuals.com)

Refractive surgery is optional eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. (wikipedia.org)
Although nonsurgical correction (ie, glasses, contact lenses ) for patients with low-level hyperopia and presbyopia has been widely successful throughout the world, the surgical correctional procedures have been somewhat less accepted. (medscape.com)
The goal of most refractive surgeries is to reduce or eliminate the need for eyeglasses or contact lenses. (ucihealth.org)
The surgical procedures , which include Lasik and PRK surgery, often aim to eliminate service members' dependence on glasses or contact lenses in austere environments. (health.mil)
While these procedures can be very effective, they can only improve vision problems that are correctable with glasses or contact lenses. (atlanta2020.com)
I used to be a regular swimmer which became a problem as I could not wear contact lenses in the pool.More than a decade after the ICL procedure, my vision is perfect. (centreforsight.com)

As myopia has been identified as the most prevalent refractive error all over the world, 10 , 11 the correlation between myopia and axial length of the eye was extensively discussed, revealing a positive correlation between the absolute value of myopia and axial length. (dovepress.com)
Myopia is an extremely common refractive error in Singapore with 82 percent of the 20-year-olds suffering from this condition -- one of the highest in East Asia. (asiaone.com)

This study is a retrospective study in which we analyzed the preoperative data of 1401 patients (1401 eyes) who underwent keratorefractive surgery (LASIK and photorefractive keratectomy (PRK) procedures) between 2016 and 2019 at Nour Eloyon Specialty Eye Center, Egypt. (dovepress.com)
Although you may not be a candidate for LASIK, the most popular refractive procedure performed today, you may be a candidate for a procedure known as photorefractive keratectomy, or PRK. (visionboston.com)
Laser assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) are two of the most common laser refractive procedures. (ucsfhealth.org)

The distribution of comments by topic domain was generally similar across types of correction and type of refractive error. (nih.gov)

Shelke K, Rishi E, Rishi P. Surgical outcomes and complications of sutureless needle-guided intrascleral intraocular lens fixation combined with vitrectomy. (medscape.com)
Thinner corneas are at risk for ectasia, haze and less predictable refractive outcomes. (dovepress.com)
This procedure delivers the same visual outcomes as LASIK and has dramatically improved the vision of millions of patients unable to undergo the LASIK procedure. (visionboston.com)
Book publication "Femtodynamics: A Guide to Laser Settings and Procedure Techniques to Optimize Outcomes with Femtosecond Lasers. (trustedlasiksurgeons.com)

Burratto and Pallikaris then combined the microkeratome technique with the use of the excimer laser to ablate tissue and to induce refractive change. (medscape.com)
Dr. Shapiro has been named a "VISX Star Surgeon," a title awarded to the top 5% of refractive surgeons nationwide by VISX, the manufacturer of the leading excimer laser system in the United States. (jurispro.com)
These are refractive procedures performed with an excimer laser. (atlanta2020.com)
What procedures are performed with the excimer laser? (atlanta2020.com)
It is an excimer laser procedure that can provide correction of presbyopia after 40 years of age. (karsiyakagoz.com)

Refractive surgery is irreversible, and these surgeries may cause side effects or not completely restore your vision to the way it was before you started to experience vision problems. (everydayhealth.com)
Every ocular procedure from cataract surgery to blepharoplasty to glaucoma treatment to antivascular endothelial growth factor injections for age-related macular degeneration to especially corneal-based surgeries PRK and LASIK disrupts the ocular surface. (crstoday.com)

Twice as many positive as negative comments were given by contact lens wearers, and 4 times as many positive comments were provided by patients who had undergone surgical correction. (nih.gov)
The similarity of problems mentioned across refractive error type and correction method suggests it will be possible to develop a single questionnaire with adequate content validity to compare the impact of different modes of correction in vision-targeted, health-related quality of life. (nih.gov)
Laser and laserlike surgical procedures for the correction of hyperopia have a checkered history. (medscape.com)
This revolutionary procedure presents convincing advantages over hyperopic LASIK and hyperopic correction via LTK. (medscape.com)
Laser-assisted subepithelial keratectomy (LASEK) is a laser surgical procedure for the correction of refractive error. (medscape.com)
Assessment of corneal parameters, especially the central corneal thickness (CCT) and the corneal curvature (the corneal power), is crucial before proceeding with laser vision correction (LVC) procedures. (dovepress.com)
Dr. Shapiro devotes his practice exclusively to laser vision correction and has performed over 25,000 refractive surgical procedures, utilizing the latest in laser technologies. (jurispro.com)
Ophthalmology procedures provided include Lasik laser based refractive correction of the eyes and other vision correction procedures. (whatclinic.com)
I believed then, as I do now, that the aging lens presents an array of opportunities for surgical vision correction and that it is our duty to counsel patients and suggest the procedure for which they are best suited. (crstodayeurope.com)
The magistrate determined that the commission did not abuse its discretion in concluding Cogan did not undergo pre-injury surgical correction to his vision, and thus the proper measure of his preinjury vision baseline was his uncorrected vision prior to the workplace injury. (findlaw.com)

Several types of corrective surgical procedures can be done for refractive errors. (ucihealth.org)
LASIK (Laser-Assisted In Situ Keratomileusis) is a surgical procedure designed to correct refractive errors and improve vision. (lasikplus.com)
For those with refractive errors, this means you can finally experience clear vision! (goldberg4lasik.com)
A therapeutic procedure for correcting REFRACTIVE ERRORS. (bvsalud.org)
Refractive errors were based We assessed the records of 265 patients to diplopia, diminished visual acuity on spherical equivalents (sphere +1/2 with vertical strabismus (130 males and and palpebral fissure changes [6]. (who.int)

The EVO Visian ICL (STAAR Surgical) is a one-piece posterior chamber phakic IOL designed with a central port to eliminate the need for an iridotomy or iridectomy. (crstodayeurope.com)

Dr. Shapiro has himself undergone refractive surgery in both eyes and now enjoys 20/20 vision. (jurispro.com)

Overview of Refractive Disorders In refractive disorders, light rays entering the eye are not focused on the retina, causing blurred vision. (msdmanuals.com)

He advanced his education further by completing a residency in complex disease management and cataract, glaucoma and refractive surgery at Georgia Eye Partners/Emory University Hospital Midtown. (thomaseye.com)
Refractive Surgery for the Glaucoma Suspect When it comes to performing refractive surgery in patients at risk for glaucoma, what factors should be considered? (medscape.com)

It can potentially lessen the requirement for surgical intervention in individuals with severe ocular surface disorders. (thefatlossninja.com)
Integrated care of these patients lessens this burden, frees up time for the ophthalmologist to see more surgical patients, and allows the optometrists to develop an effective treatment plan for both pre- and postsurgery to create a pristine ocular surface. (crstoday.com)
High-volume surgical practices take great measures to evaluate the ocular surface prior to surgical procedures. (crstoday.com)

A comparison of physician demographic and practice pattern data of 100 consecutive Ophthalmic Mutual Insurance Company (OMIC) LASIK and PRK claims and lawsuits with demographic and practice pattern data for all active refractive surgeons insured by OMIC between 1996 to 2002 was made. (nih.gov)
Koch DD " An aphoristic guide to building a refractive surgical practice. . (bcm.edu)
Pallikaris attempted this technique on blind human eyes in 1989 and on sighted human eyes in 1991, thereby creating a refractive surgical technique similar to the procedures currently in practice. (medscape.com)
1 Working as an optometrist (L.O.) in a busy surgical practice, I have observed that the disconnect can start even before the patient is referred for surgery. (crstoday.com)
By investing in the referring network of optometrists through education and hands-on workshops, your surgical practice will grow. (crstoday.com)
Licensed by the state, optometrists can only perform procedures that fall within their scope of practice. (medicalnewstoday.com)

LASIK and PRK sub-specialist David R. Shapiro, M.D. is one of the nation's leading authorities on refractive eye surgery. (jurispro.com)
Some studies have shown that, compared with LASIK and PRK, phakic IOL surgery provides better BCVA and refractive predictability, greater refractive stability, and higher patient satisfaction. (crstodayeurope.com)

In his objections, Cogan asserts the magistrate erred (1) in failing to construe his childhood injury as including a prior corrective surgical procedure, and (2) in determining Cogan's pre-workplace injury visual baseline for purposes of calculating his loss of sight. (findlaw.com)

These findings may be used in the future to help improve the quality of care for patients undergoing refractive surgery and to provide data for underwriting criteria and risk management protocols to manage proactively and perhaps reduce the risk for claims and lawsuits against refractive surgeons. (nih.gov)
Dr. Shapiro has been recognized as a world leader in refractive surgery by EyeWorld and as one of the "nation's top refractive surgeons" by Primary Care Optometry News, two of the nation's leading eyecare journals. (jurispro.com)
As a recognized leader in his field, Dr. Shapiro has helped teach refractive surgery to over 1,000 eye surgeons from across the United States and around the world. (jurispro.com)
The surgical procedures are performed by surgeons, and our optometrits care for you throughout the post-surgical recovery period. (sve.com)
Dr. Ella Faktorovich has extensive qualifications that we estimate place her among the top LASIK and refractive surgeons in the United States. (trustedlasiksurgeons.com)

A retrospective observational cross-sectional study in which we analyzed the preoperative data of 1401 Egyptian myopic patients (1401 eyes) who underwent keratorefractive procedures between 2016 and 2019 in a private eye surgery center. (dovepress.com)
While it is classified as an elective surgery, patients are often extremely happy with the outcome and their decision to have a Lasik or PRK procedure. (health.mil)
LASIK is considered a safe and effective procedure for the majority of patients. (lasikplus.com)
Some patients may feel slight pressure or a sensation of movement during certain steps of the procedure, but it is typically not painful. (lasikplus.com)
Patients leave the surgery center with the assistance of a nurse soon after the procedure concludes. (crstoday.com)
Cordlife is the first company in Asia to let patients undergoing refractive eye surgery using lenticule extraction method (e.g. (asiaone.com)
Having patients' OSD well controlled in advance of the surgical consultation will reduce the number of patients who, although asymptomatic preoperatively, suffer from ocular discomfort, vision fluctuations due to decreased tear breakup time, and increased inflammation in the postoperative period. (crstoday.com)
Corneal drying results in refractive changes that are magnified by these IOLs, potentially causing distorted vision and unhappy patients. (crstoday.com)
The success rate with this procedure is excellent, with most patients achieving 20/20 vision or better upon completion. (sve.com)
We offer a variety of free educational offerings to help patients learn more about refractive surgery, including evening seminars, patient education materials and personalized consultations. (ucsfhealth.org)
Stroke Risk in Medically Treated Asymptomatic Carotid Stenosis Should patients with asymptomatic carotid artery stenosis undergo carotid procedures, or does medical therapy provide sufficient protection against stroke? (medscape.com)
In this retrospective cohort study we reviewed the profile and surgical outcome of vertical strabismus patients attending a clinic in Yazd city in the Islamic Republic of Iran. (who.int)
Dans la présente étude de cohorte rétrospective, nous avons examiné le profil des patients atteints d'un strabisme vertical consultant en établissement de soins dans la ville de Yazd (République islamique d'Iran) et l'issue des interventions chirurgicales. (who.int)
L'étude des dossiers médicaux de 265 patients a mis en évidence une déviation verticale simple chez 19,2 % et un strabisme horizontal et vertical chez 80,8 % d'entre eux. (who.int)
Le dépistage, le diagnostic et la prise en charge précoces sont requis dans les familles affectées et chez les patients ayant des antécédents familiaux de strabisme. (who.int)

In recent years, cataract surgery has become a highly precise and safe surgical procedure due to phacoemulsification technique and advanced intraocular lens (IOL) designs. (hindawi.com)

Conductive keratoplasty (CK) is a safe non-ablative, corneal procedure for the treatment of low hyperopia and presbyopia. (medscape.com)
Fellows will gain expertise in the surgical management of keratoplasty and other anterior segment procedures, along with the medical aspects of a broad spectrum of corneal diseases. (umaryland.edu)

These guidelines are designed to assist ophthalmologists in providing truthful, informative advertising of refractive surgery. (aao.org)

Numerous refractive surgery procedures are utilized in the management of hyperopia and presbyopia. (medscape.com)

Additional risk factors that increase in importance with higher surgical volume include physician gender, advertising use, preoperative time spent with the patient, and comanagement with optometrists. (nih.gov)
Partnering with referring optometrists to develop a treatment plan prior to surgical referral can be a huge time saver. (crstoday.com)
For optometrists, treating OSD before the patient is referred for a surgical consultation is vital. (crstoday.com)

To help the military's vision care community stay up to date on the latest technology and research, the 2022 Military Refractive Surgery Safety and Strategy Symposium (MRSSSS) convened in late January. (health.mil)

Using an outcome of whether or not a physician had a history of a claim or lawsuit, logistic regression analyses were used separately for each predictor as well as controlling for refractive surgery volume. (nih.gov)
To face increasing demands on visual and refractive outcome, efforts have been made to further improve IOL designs. (hindawi.com)
All eye surgical procedures carry a level of risk including not obtaining the desired outcome through to varying levels of visual loss. (centreforsight.com)

The LASIK procedure itself involves little or no discomfort both during the procedure and also usually through the recovery process. (sve.com)

Like any surgical procedure, LASIK does carry some risks and potential complications, although they are rare. (lasikplus.com)
RÉSUMÉ Le diagnostic et la prise en charge précoces d'un strabisme sont nécessaires pour éviter les complications telles qu'une amblyopie. (who.int)

It results from an imperfect curvature of eye that causes refractive error. (butlereyecenter.com)

Dr. Cofie has strong clinical proficiency in the diagnosis and management of eye diseases, binocular vision disorders, specialty contact lens fittings and co-management of surgical procedures. (thomaseye.com)

These are a group of surgical procedures designed to permanently reduce or eliminate the need for corrective eyewear to see distant objects. (atlanta2020.com)

The lasik is short for eyes surgical treatment performed by professional doctors via lasers. (rabbinevins.org)

In some cases, you might be able to consider refractive (or laser) surgery, lens implants, or corneal inlays. (everydayhealth.com)

Usually, a person can go home soon after the procedure. (msdmanuals.com)

The first theoretical work on the potential of refractive surgery was published in 1885 by Hjalmar August Schiøtz, an ophthalmologist from Norway. (wikipedia.org)
Italian ophthalmologist Camellin is credited with developing the original LASEK procedure when he described the Camellin technique in ophthalmic literature in 1999. (medscape.com)
An ophthalmologist will usually perform laser or surgical procedures. (medicalnewstoday.com)
Before deciding on such a procedure, people should have a thorough discussion with an ophthalmologist (a medical doctor who specializes in the evaluation and treatment [surgical and nonsurgical] of eye disorders) and should carefully consider their own needs and expectations, along with the risks and benefits. (msdmanuals.com)

LASIK is an outpatient surgical procedure. (medlineplus.gov)
Laser refractive surgery is a very short outpatient procedure that generally takes less than 30 minutes. (ucsfhealth.org)

To find out the correlation between myopic refractive error, corneal power and central corneal thickness (CCT) in the adult Egyptian population. (dovepress.com)
3 , 14-16 The purpose of this work is to find out if there is any correlation between corneal parameters (namely, central corneal thickness and corneal power) and the refractive error in the myopic adult Egyptian population. (dovepress.com)

Phakic IOL surgery also avoids the risks of postoperative corneal ectasia 5 and of retinal detachment associated with refractive lens exchange. (crstodayeurope.com)

7. Which of these vision problems does refractive surgery correct? (ucihealth.org)
Finally, LASIK eye surgical treatment is a secure and also reliable way to correct typical vision troubles. (zagran-pasport.info)

If you have actually had cataract surgical treatment in both eyes, PCO can impact both eyes, yet each eye may be impacted at various times. (schemic.us)
If you determine with your consultant doctor to have laser cataract surgical treatment (additionally referred to as femto-phako) your specialist will certainly utilize femtosecond laser to partially malfunction the cataract. (schemic.us)
Laser eye surgical treatment, where power beam of lights punctured part of the eye, might be used. (schemic.us)
The good news is that YAG laser treatment is accomplished as an out-patient procedure, so there is no overnight stay included. (schemic.us)
Posterior pill opacification occurs since cells of the natural lens continuing to be after cataract surgical treatment have grown on the pill. (schemic.us)
This will lead to the substantial-speed online internet site, that provides millions of people the ease of managing themselves via lasik surgical treatment. (rabbinevins.org)
If you are thinking about LASIK eye surgical procedure, it is very important to understand what it is, just how it functions, and also what to anticipate throughout and also after the treatment. (zagran-pasport.info)
Nonetheless, LASIK eye surgical treatment is not suitable for everyone. (zagran-pasport.info)
If you are thinking about LASIK eye surgical treatment, it is essential to discuss your candidacy with a certified eye doctor. (zagran-pasport.info)
In addition, supracor treatment cannot be performed in cases that interfere with the laser procedure such as pregnancy, rheumatic or severe metabolic disease. (karsiyakagoz.com)
Otolaryngology Considerations of Pituitary Surgery The surgical planning and treatment of pituitary adenomas requires a multidisciplinary approach, with otolaryngologists playing a critical role. (medscape.com)

Dr.) Tyler Miles, an aerospace optometrist at the Navy Refractive Surgery Center at Naval Medical Center San Diego. (health.mil)

Posterior capsulotomy, or YAG laser capsulotomy, is a laser procedure to treat over cast vision after cataract surgical procedure by creating an opening in the gloomy lens pill. (schemic.us)
Coronary sinus, normally located between the LEFT ATRIUM and LEFT VENTRICLE on the posterior surface of the heart, can serve as an anatomical reference for cardiac procedures. (bvsalud.org)

Plastic surgical procedures performed include reshaping of facial organs, breast reshaping, hair transplantation, Liposuction weight reduction procedures, facelifts, tummy tucks and genital reshaping. (whatclinic.com)

The PRK procedure also goes by several other names: LASEK (pronounced LAS-ECK), epi-LASIK, and surface ablation. (visionboston.com)

Before the procedure, anesthetic eye drops are applied to numb the eyes and ensure your comfort throughout the surgery. (lasikplus.com)

Anatomy1

Diseases5

Analytical, Diagnostic and Therapeutic Techniques and Equipment7

Information Science1

Enabled the development of1

Cornea19

Astigmatism8

Corneal refractive3

Candidates for refractive surgery2

American Academy of Op1

Cataract surgery and refractive2

Nearsightedness1

Contact lenses6

Myopia2

Photorefractive keratectomy3

Type of refractive1

Outcomes4

Excimer5

Surgeries2

Correction10

Errors5

Visian ICL1

Undergone1

Retina1

Glaucoma2

Ocular surface3

Practice6

LASIK and PRK2

Corrective surgical1

Surgeons5

Patients15

Intraocular lens1

Keratoplasty2

Ophthalmologists1

Hyperopia1

Optometrists3

20221

Outcome3

Involves1

Complications2

Curvature1

Specialty1

Reduce or eliminate the need1

Lasers1

Lens implants1

Soon after the procedure1

Ophthalmologist4

Outpatient2

Myopic2

Ectasia1

Correct2

Treatment11

Surgery center1

Posterior2

Include1

LASEK1

Eyes1