I migliori medici per il trattamento di Uveite (Infiammazione dell'occhio) - TOP-46 medici

Il Professore Associato Muhammet Derda Ozer è specializzato nel trattamento dell'uveite con formazione avanzata presso il Wills Eye Institute ed esperienza in studi clinici.

• Ha completato un prestigioso osservership in oncologia oculare presso il Wills Eye Institute
• Ha partecipato a importanti studi clinici per l'uveite nella Malattia di Behçet
• Riconosciuto dal Consiglio Internazionale di Oftalmologia con molteplici certificazioni
• Membro attivo dell'Associazione Oftalmologica Turca

Experience

- Resident physician in the ophthalmology service of Bellvitge Hospital (2001).

-Commission for training in surgery (cataract surgery) at the San Rafael Hospital

- Study Committee of the Clinical and University Hospital of Santiago de Compostela in the Department of Oculoplastic and Orbital Surgery (Drs. Perez-Moreira and Prada, 2001)

Assistance in consultation and surgery at the Teknoftal Institut Oftàlmic and head of the orbital and oculoplastics department (since 1999)

Since 2001, Deputy Ophthalmologist of the Health Service and the University City of Bellvitge. Since 2003, Head of the Orbital and Oculoplastics Department with accreditation by the Center for Surveillance in Orbital Tumors and Orbital Decompression Surgery for Thyroid Disease.

Resident Lecturer (since 2006)

Specializations: lens surgery, refractive surgery, orbital surgery, lacrimal duct surgery and oculoplastics.

Qualification

Graduate of the Faculty of Medicine and Surgery of the University of Barcelona with outstanding qualifications and an outstanding award

Ophthalmology specialist via MIR

Doctorate at the Autonomous University of Barcelona

Publications

Participation in more than 20 national and international round tables.

Presentation of 25 courses and 46 papers at national and international conferences.

Publication of 2 original articles in national and international specialized journals.

Co-author of 3 books on ophthalmology.

Scientific societies

Member and Fellow of the Spanish Society of Ocular and Orbital Plastic Surgery.

Member and Associate of the Catalan Society of Ophthalmology.

Member of the Ulsa del Mona Foundation, Maputo Hospital, Mozambique 2008

Ponpawee Jindarak, M.D.

Ophthalmologist

Graduated (M.D. From)

Doctor of Medicine, Faculty of Medicine, Chulalongkorn University

An eye care specialist. Unlike optometrists and opticians, I am a doctors of medicine (MD) or doctors of osteopathy (DO). I have specialized training and experience in diagnosing and treating eye and vision conditions.

Certificates

Certificate of Ophthalmology, Faculty of Medicine, Chulalongkorn University

International Clinical Fellowship in Glaucoma at Illinois Eye and Ear Infirmary, Department of Ophthalmology, University of Illinois, Chicago, USA

Current Positions

Ophthalmologist at Intrarat Hospital

Dr. Ermal Dida is an experienced ophthalmic surgeon. He specializes in refractive vision correction and oculoplastic surgery. He is the founder and lead surgeon at Dida Roka Eye Clinic in Prishtina. Dr. Dida is known for his skill in laser vision correction and advanced eyelid procedures, such as entropion repair and ptosis correction.

He also works as an ophthalmic surgeon at the Italian Eye Hospital. There, he focuses on refractive and oculoplastic services. Dr. Dida’s expertise includes general ophthalmology and anterior segment care. He is dedicated to serving both local and regional patients. Dr. Dida speaks several languages, which helps him care for a wide range of patients.

EDUCATION

Mersin University, Faculty of Medicine, 2009

Istanbul Göztepe Training and Research Hospital, Residency in Ophthalmology, 2009 to 2013

PROFESSIONAL EXPERIENCE

Mardin Midyat State Hospital – Specialist Ophthalmologist, 2014 to 2020

Mardin Training and Research Hospital – Specialist Ophthalmologist, 2020 to 2022

Başakşehir Çam and Sakura City Hospital – Specialist Ophthalmologist, 2022to 2024

Westeye Hospital, Erbil – Specialist Ophthalmologist, 2024 to 2025

Istanbul Tema Hospital – Specialist Ophthalmologist, 2024 to 2025

AREAS OF EXPERTISE

-Cataract and Refractive Surgery

-Corneal Diseases and Keratoplasty

-Strabismus and Strabismus Surgery

-Eyelid and Lacrimal System Surgery

-Ocular Trauma Surgery

TRAINING & CERTIFICATIONS

-Vitrectomy Training at Ulucanlar Eye Training and Research Hospital, 2020

MEMBERSHIPS

-Member of the Turkish Ophthalmological Association (TOD)

PUBLICATIONS

1)Changes caused by fluorescein in the tear film evaluated with hybrid break-up time test as a new method - Part Two: Its effect on breakup locations and other quantitative values, Photodiagnosis and Photodynamic Therapy, 2023

2)The profile of patients attending to the general emergency department with ocular complaints within the last year: is it a true ocular emergency?, BMC Ophthalmology, 2024

3)Medium-term outcomes of three horizontal muscle surgery in large-angle infantile esotropia, Journal of Pediatric Ophthalmology & Strabismus, 2014

4)Evaluation of Anterior Segment Parameters Using Scheimpflug Topography Device in Patients Undergoing Nd:YAG Laser Posterior Capsulotomy: Retrospective Study, Türkiye Klinikleri Journal of Ophthalmology, 2024

5)Publication patterns of ophthalmology residency dissertations in Turkey, European Journal of General Medicine, 2015

6)Evaluation of the Effect of Infection and Immunity on the Tear Film by Scheimpflug-Placido Disc Topography – A Case Control Study, Photodiagnosis and Photodynamic Therapy, 2023

7)Changes caused by fluorescein in tear film by hybrid break-up time test - Part One: On quantitative values, Photodiagnosis and Photodynamic Therapy, 2022

8)An easy and practical method for toric intraocular lens implantation: marking corneal astigmatic axis at slit-lamp, International Ophthalmology, 2017

9)Slanted medial rectus recession is effective in the treatment of convergence excess esotropia, Journal of Pediatric Ophthalmology & Strabismus, 2014

10)A reasonable option in vitrectomized eyes: manual small incision cataract surgery, International Journal of Ophthalmology, 2014

11)The Role of Systemic Inflammation in Acquired Nasolacrimal Duct Obstruction, Beyoglu Eye Journal, 2023

12)A New Approach: Determination of the Safe Surgical Margin in Pterygium Surgery, Klinische Monatsblätter für Augenheilkunde, 2023

Dr. Arsim Hajdari is a leading ophthalmologist and serves as Chief Clinical Officer at the Italian Eye Hospital in Pristina, Kosovo. He earned his MD from the University of Pristina. He specialized in ophthalmology at the University Clinical Center of Kosovo in 2019. Dr. Hajdari also holds a PhD in Ophthalmology from the University “Goce Delchev” in Stip, completed in 2025.

Since May 2021, Dr. Hajdari has treated over 30,000 patients. He has performed more than 4,000 TransPRK (SmartSurface no-touch laser) procedures. He introduced several advanced treatments to Kosovo, such as Laser-Guided Cross-Linking, Beovu (Brolucizumab) injections, IPL therapy for dry eye, and TransPTK for corneal irregularities.

Dr. Hajdari’s expertise includes refractive surgery, retina surgery, anti-VEGF injections, trauma care, vitrectomy, and oculoplastics. He lectures at the University for Business and Technology (UBT). He has also presented research at EURETINA Athens 2025.

He is a member of the American Academy of Ophthalmology (AAO), EuRetina, the Asia-Pacific Glaucoma Society, and the College of Surgeons of Kosovo.

Dr. Lee Young Seob is a board-certified ophthalmologist and Chief Director. He specializes in retina, cataract, and advanced vision correction procedures. His expertise includes SMILE, Contoura Vision, and lens implant surgery. Dr. Lee graduated at the top of his class from Kyung Hee University College of Medicine. He completed his residency at Kyung Hee University Hospital. He has also served as a clinical professor at Ajou University Hospital. Dr. Lee has held leadership positions at major eye clinics.

He has performed over 15,000 cataract and refractive surgeries, including LASIK, LASEK, SMILE, and ICL implantation. Dr. Lee is known for his surgical skill. He holds certifications of excellence in SMILE LASIK, ICL/Toric-ICL, and several intraocular lens implantations, such as LISA Tri, FineVision, and PanOptix.

Dr. Lee is an active member of leading ophthalmology societies. These include KOS, AAO, KSCRS, ASCRS, and ARVO.

Op. Dr. Veysi

Ophthalmologist

Education

Specialty Training
2011 - 2015
Izmir Atatürk Training And Research Hospital

Undergraduate Education
2003 - 2010
Ankara University Medicine Faculty

Experience

2022 -
ClinicExpert - Ophthalmologist

2021 - 2022
Aile Hospital - Ophthalmologist

2021 - 2022
Ataköy Hospital - Ophthalmologist

2020 - 2022
Maltepe University Medicine Faculty - Ophthalmologist

2018 - 2020
Memorial Şişli Hospital - Ophthalmologist

2017 - 2018
Aydın University Medical Park Hospital - Ophthalmologist

2017 - 2018
Gaziosmanpaşa Hospital - Ophthalmologist

2016
Artvin Hopa Hospital - Ophthalmologist

2010 - 2015
Izmir Atatürk Training and Research Hospital - Research

Skills

• I-Lasik Operation
• Lasik Operation
• Laser Surgery
• PRK Surgery
• Cataract Operation
• Strabismus Surgery
• Glaucoma Surgery
• Oculoplast (Upper Lower Lid Aesthetic, Eyebrow Lift, Ptosis Operation)
• Ektropion Entropion Operation
• Dsr, Botox, Filling, Medical Aesthetic

Dr. Lee Kwan Hoon is an ophthalmologist and Chief Director. He specializes in retina, cataract, vision correction, SMILE, Contoura, and lens implantation. He graduated from Dankook University College of Medicine. He completed his residency and a retina fellowship at Dankook University Hospital. Dr. Lee also works as an adjunct professor at Dankook University.

He has held several leadership roles. These include Director at BGN Eye Clinic Jamsil Lotte Branch, Head of Ophthalmology at Armed Forces Capital Hospital, and Director of the Retina Center at Kim Eye Clinic in Masan. Dr. Lee has performed over 10,000 cataract and refractive surgeries. He has also completed more than 15,000 retinal procedures and surgeries.

Dr. Lee is a member of the Korean Ophthalmological Society, American Academy of Ophthalmology, and Korean Retina Society. He is certified in LISA Tri, FineVision, and PanOptix intraocular lens implantation. He is also a certified expert in ReLEx SMILE by Carl Zeiss.

CURRICULUM VITAE

Place and Date of Birth

• Adana, 1981

Language Skills

• English

Education and Experience

• • 1999-2005 Istanbul University, Istanbul Faculty of Medicine, Istanbul
• • 2005-2010 Marmara University, Faculty of Medicine, Ophthalmology, Istanbul (Specialization)
• • 2010-2012 Muş State Hospital (Compulsory Service)
• • 2011 Yale University New Haven Hospital, Ophthalmology, Connecticut / USA
• • 2012-2017 Istanbul University, Istanbul Faculty of Medicine, Ophthalmology, Istanbul (Specialist Dr.)
• • 2015 Massachusetts Eye Research and Surgery Institution, United States (Fellow / Research assistant)
• • 2017 Istanbul University, Istanbul Faculty of Medicine, Ophthalmology, Istanbul (Associate Professor Dr.)

Number of Scientific Publications

• Over 150 scientific presentations, publications and articles

Case Experience

• Experience of over 15.000 surgery cases in 16 years

Membership

• • Turkish Ophthalmology Association (TOD)
• • Turkish Ophthalmology Association Uvea-Behçet Unit
• • American Academy of Ophthalmology (AAO)
• • American Uveitis Society (AUS)
• • International Ocular Inflammation Society (IOIS)
• • International Society for Behçet's Disease (ISBD)
• • The Foster Ocular Immunology Society (FOIS)
• • Tarsus American College Alumni Association

Dr. Verges graduated in Medicine and Surgery from the University of Barcelona in 1980 and moved to Boston (USA) to conduct basic research in ophthalmology, obtaining a PhD in Biology from Harvard University and defending his doctoral thesis on the mechanisms of tear secretion, which would become the basis for understanding the pathology of dry eye syndrome (thesis presented in Barcelona, ​​1983) and which earned him the National Research Prize (1983).

Currently, Dr. Carlos Verges carries out his professional activity as the Director of the Ophthalmology Service of the Dexéus University Hospital, together with his entire medical team from the advanced ophthalmology department, where he has a high-quality technological, medical and surgical team.

His area of ​​interest is focused on the field of cataract and neurophysiological mechanisms of vision, especially in relation to sports.

Professional experience

1983-1986 Associate Professor, Department of Ophthalmology, Faculty of Medicine, University of Barcelona, ​​Spain

1986-1989 Head of the Anterior Segment Unit, Department of Ophthalmology, Barcelona Hospital Clinic, Spain.

1986-1991 Professor of Ophthalmology, Faculty of Medicine, University of Barcelona, ​​Spain.

1990-1992 Head of Ophthalmology Service, Hospital del Mar, Barcelona.

1989-1999 Head of the Ophthalmology Department, Sagrada Familia Clinic, Barcelona, ​​Spain.

From 2000 to present, President and CEO of the Dr. Carlos Verges Private Foundation.

2000-2007 Head of the Ophthalmology Department, Institut Universitari Dexeus, Barcelona, ​​Spain.

2007 – present General Director of the “Advanced Ophthalmology Department Dr. Verges”, Barcelona, ​​Spain.

2018-present President and Head of the Department of Ophthalmology. University Hospital Dexeus Quironsalud. Polytechnic University of Catalonia.

Awards :

- National Research Prize 1984. Ministry of Education and Science: "The mechanism of tear secretion. The importance of beta-adrenergic receptors in the lacrimation of the lacrimal glands."

- National Prize for the best doctoral dissertation, Shibre Medal, 1984 "Personal contribution to the study of labial secretion. Determination of beta-adrenergic receptors in tear cells"

- National Pharmaceutical Industry Award 1987: "Treatment of immunological rejection in corneal transplantation using cyclosporine A."

- American Society of Implant Refractive Surgery (ASCRS) Award for the best scientific video presented at the annual conference: "Pseudo-Real Housing". First Prize. Seattle, USA, April 1999.

- Award for the most important technical innovation of 1999 from the Spanish Society.

Implantation-refractive surgery. Speaking at the National Congress held in Madrid 1999.

- 2000 Best Scientific Contribution Award "Laser Non-Penetrating Deep Sclerectomy" presented at the American Academy of Ophthalmology Meeting, AAO - Dallas, USA, October 2000.

- Best Paper Award for “GDx Analysis of Retinal Nerve Fiber Layer Thickness after LASIK” presented at the American Society of Cataract and Refractive Surgery, ASCRS, May 2004, San Diego, USA.

- Finalist for the King Jaume I Prize for Basic Research, 2005, sponsored by the Board of Trustees of the Generalitat of Valencia and the Valencian Foundation for Advanced Research.

- Surgical Technical Video Award: "MICS under Vision ICL, The Hook Technique"

Presented at the IX International Congress of Cataract and Refractive Surgery, May/June 2006, Belo Horizonte, Brazil.

Membership in scientific societies

Member of the Executive Board of the International Society of Refractive Surgery (ISRS) and the American Academy of Ophthalmology (AAO).

Member of the editorial board of Ophthalmology Times. Europe.

Member of the editorial board of Cataract and Refractive Surgery (USA).

Member of the Editorial Board of Cataract and Refractive Surgery Today Europe.

Member of the European Society of Cataract and Refractive Surgery (ESCRS).

Scientific reviewer of the journal: Cornea, Journal of Cataract and Refractive Surgery, American Academy of Ophthalmology, Cataract and Refractive Surgery and Archives of the Spanish Society of Ophthalmology.

Jakub Ciecierski is a specialist in the field of ophthalmology.

The doctor admits patients as part of specialist consultations, as well as performs a number of outpatient procedures, such as: 

OCT, RNFL, Laser therapy, Fluorescein Angiography

Diseases treated:

glaucoma

cataract

eye diseases

eyesight defects

conjunctivitis

myopia

dry eye syndrome

macular degeneration

astigmatism

allergic eye diseases

Dr. Sumet Supalaset, MD, is a specialist in cornea and refractive surgery. He holds certifications from top institutions in London, Kyoto, and Chiang Mai University. He completed observership training at UCLA. Dr. Sumet earned his bachelor's degree in ophthalmology from Phramongkutklao Hospital and graduated with honors from Chulalongkorn University in 1997.

He has published research articles in international journals. His work focuses on LASIK, corneal diseases, and advanced refractive procedures. Dr. Sumet is skilled in many surgical techniques, including LASIK, SMILE, PRK, ICL, phacoemulsification, corneal transplantation, and tumor excision. He is a former lecturer at Chulabhorn Hospital. Dr. Sumet speaks Thai, English, Chinese, and Japanese.

Experience:

1. Konya-Karapınar Kutören Health Center\ General Practitioner
2. KonyaProvincial Deputy Directorate of Health
3. KonyaProvincial Health DeputyDirectorate
4. Istanbul Fatih Tuberculosis Dispensary
5. University of Frankfurt \ Darmstadt Eye Clinic
6. Istanbul Taksim State Hospital\ Eye Diseases
7. Istanbul University Cerrahpaşa Faculty of Medicine \ Chief Assistantof the Department of Ophthalmology
8. Istanbul University Cerrahpaşa Eye Bank \ Founder (MedicalDirector)
9. TOD\ Chairman
10. Istanbul University Cerrahpaşa - Cerrahpaşa Faculty of Medicine\ First Head of the Department of Ophthalmology
11. Demiroğlu-Bilim University \ Head of Ophthalmology Department
12. Florence Nightingale Hospitals \ Eye ClinicCoordinator

Specialties:

1. Vaccinating the child age group
2. Follow-up of eye eclipse in Behçet’s disease with iris and fundus fluorescein angiography (FFA)

Priority treatments:

1. Anterior segment surgery (cataract + IOL implantation, keratoplasty)

Special advanced health technologies:

1. Arslan closed cornea technique
2. Arslan covered cornea technique
3. Retrograde glaucoma tube implantation

Leadership and Administrative Roles (Turkish Ophthalmology Association - TOD):

• Various administrative roles at TOD including:
• President of TOD IstanbulBranch (2006-2010, 2008-2010)
• General Secretary (2015-2017)
• President of TOD (2017-2019)
• Member of TOD CentralExecutive Board (2011-2013, 2013-2015)
• Member of Executive Board of the Cornea and Ocular Surface(COS) Unit of TOD (1994-2023)
• Member of Executive Board of TOD Cataract and Refractive SurgeryUnit (2016-2018)

Research and Publications:

• Authored 57 original articlesin international peer-reviewed journals
• Authored 56 articles in national peer-reviewed journals
• Presented 178 papers at national conferences and 102 papersat international conferences
• Authored 1 book and 6 book chapters
• Developed two original surgicaltechniques and the Retrograde GlaucomaTube Implantation technique
• Served on editorial boardsof various international and national journals

Memberships and Affiliations:

• Member of American Academyof Ophthalmology (AAO) and EuropeanSociety of Cataract and Refractive Surgeons (ESCRS)
• Examiner for European Board of Ophthalmology (EBO) exams representing Turkey

Awards:

• Received awards from IstanbulUniversity and TÜBİTAK

Education:

Theppachai Thammikasakul, M.D. Ophthalmologist

Work and Educational Experiences 

Graduated (M.D. From)

Doctor of Medicine, Faculty of Medicine, Phramongkutklao College of Medicine

Certificates

Ophthalmology Certificate, Phramongkutklao Hospital

Sub-board / Fellowship in Corneal and Refractive Surgery at Khonkaen University

Current Position

Theppachai Thammikasakul is currently working as Ophthalmologist at Intrarat Hospital

Dr. Ali Riza Cenk Celebi is a Professor of Ophthalmology at Acibadem University (2023–2025). He practices at Acibadem Maslak Hospital (2024–2025). He completed a glaucoma fellowship at Harvard/Mass Eye and Ear in 2016. His clinical work covers glaucoma (MIGS, seton procedures), cornea (limbal stem cell surgery), lacrimal surgery (scarless endoscopic DCR), medical retina (intravitreal injections), myopia control in children, and orbital surgery.

He earned his MD from Hacettepe University and ranked 3rd in his class. He began his ophthalmology residency after placing 11th in Turkey’s TUS exam. Certifications include ICO Basic and Clinical (2010), FEBO (2015), Turkish Board (2016), Advanced ICO/FICO (2017), and USMLE Step 4. His awards include Acibadem Academic Achievement (2015–2023), Best Presentation (2022), and TOD awards (2022–2023). He has published 58 international articles and 15 books. He holds an MSc in Biological Data Science (GPA 3.94/4.00, top of term) and completed training in AI in Healthcare in 2020.

Specializzato in chirurgia della retina e vitreoretinica, il Dott. Sönmezer ha dedicato oltre 20 anni alla cura degli occhi, inclusi i complessi casi di uveite presso i principali ospedali turchi.

• Formazione presso l'Istanbul Okmeydanı Training and Research Hospital
• Socio fondatore del Kayseri Maya Eye Hospital
• Esperto in condizioni retiniche legate all'uveite
• Attuale focus sui trattamenti avanzati presso l'Antalya Medical Park Hospital

Prof. Yusuf Yıldırım, M.D.

Ophthalmology

Areas of Expertise and Interest

• Cataract and Refractive Surgery
• Cornea and Ocular Surface Diseases
• Ocular Surface Reconstruction
• Cornea Transplantation (PK, DALK, DMEK)
• Refractive Surgery (PRK, LASIK, SMILE, phakic IOLs)

Education and Career

• 2006 – 2010, Beyoğlu Eye Training and Research Hospital / Resident in Ophthalmology
• 2007, Sub-Investigator, Clinical Trial on Age-Related Macular Degeneration (Neovista, Inc.)
• 2009 – 2011, Sub-Investigator, Keraflex Treatment for Myopia (Avedro, Inc.)
• 2016, European Board of Ophthalmology (FEBO) Certification
• 2018, International Council of Ophthalmology (FICO) Certification
• 2019, Cornea and External Disease Subspecialty Diploma
• 2020, Membership, Royal College of Surgeons of Edinburgh
• Until 2024, Professor and Clinical Education Chief, Başakşehir Çam and Sakura City Hospital
• 2024 – Present, Professor and Clinical Educator, Istanbul Medipol University, Medipol Acıbadem District Hospital

Career

Born in Trabzon in 1982, Prof. Yusuf Yıldırım completed his high school education at Kanuni Anatolian High School and earned his medical degree from Istanbul University Faculty of Medicine in 2006. He pursued his residency at Beyoğlu Eye Training and Research Hospital, where he contributed to clinical trials on age-related macular degeneration and myopia treatment. Prof. Yıldırım's clinical focus lies in cataract and refractive surgeries, as well as corneal and ocular surface diseases. He has performed over 10,000 cataract surgeries, numerous ocular surface reconstructions, and advanced corneal transplants (PK, DALK, DMEK). His refractive surgery experience includes PRK, LASIK (mechanical and femtosecond), SMILE, and phakic IOL implantation. He continues to participate in clinical research, particularly involving toric phakic IOLs. He holds multiple distinguished certifications and memberships including FEBO (2016), FICO (2018), a Corneal Subspecialty Diploma (2019), and Membership of the Royal College of Surgeons of Edinburgh (2020). In his academic career, Prof. Yıldırım has contributed to the education of numerous residents and has published widely in the field.

Publications

• Author of 84 peer-reviewed scientific articles
• H-index: 17 (Web of Science), 23 (Google Scholar)
• Total Citations: 830 (Web of Science), 1,451 (Google Scholar)

Books and Book Chapters

• Ocular Surface Disorders
• Corneal Diseases and Surgery
• Refractive Errors (including Presbyopia)

Certifications and Awards

• European Board of Ophthalmology (FEBO), 2016
• International Council of Ophthalmology (FICO), 2018
• Cornea and External Disease Subspecialty Diploma, 2019
• Member of the Royal College of Surgeons of Edinburgh, 2020
• 2nd Place – Best Poster Award, ESCRS Conference, London, 2014

Dr. Yoon-Jung Jo is a board-certified ophthalmologist and Director at Samsung Miracle Eye Clinic (Gangnam, Seoul). She earned her MD and completed an ophthalmology residency at Hallym University Medical Center. She later served as a visiting professor and clinical faculty member. She also served as Director of Cheonan Kim Eye Clinic.

She is a refractive surgery specialist. Her focus includes SMILE, LASIK, and 1:1 customized astigmatism and vision correction. Dr. Jo is a certified ZEISS SMILE Excellent Surgeon. She is an active member of KOS, AAO, APAO, KSCRS, ESCRS, ASCRS, ARVO, KEEDS, and KCLS.