Archive for the ‘Keratoconus’ Category

Bochner Establishes a Complimentary Keratoconus Clinic

Thursday, August 24th, 2017

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Patients with keratoconus or suspected keratoconus require corneal imaging to show anterior curvature, anterior elevation, posterior elevation, and pachymetry. Sophisticated corneal tomography and topography imaging allows for an early diagnosis of keratoconus and follow-up examinations can document stability or progressive disease.

At Bochner, our Keratoconus Clinic allows us to devise and review with patients and referring doctors a detailed treatment plan. Treatment options depend on a patient’s age, level of best-corrected spectacle acuity and uncorrected acuity, dioptric difference across a cornea, pachymetry, corneal curvature, and/or the presence of any significant corneal scarring. We have developed a decision tree that guides our recommendations on the following clinical options:

  1. Corneal crosslinking to stabilize a cornea.
  2. Corneal crosslinking + Topography-guided PRK to stabilize a cornea and improve best-corrected spectacle acuity by reducing irregular astigmatism.
  3. Corneal crosslinking + Intracorneal rings to allow enhanced contact lens wear in corneas too thin for Topography-guided PRK.
  4. Toric implantable contact lens to enhance uncorrected acuity.
  5. PRK and limited corneal crosslinking to improve uncorrected acuity.
  6. RGP, hybrid, or scleral lenses to improve best-corrected acuity.

Laser Cataract Surgery

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Since acquiring the first Catalys femtosecond laser in Canada 5 years ago the percentage of patients choosing this advanced technology has continued to increase. One-hundred percent of the 34 Ophthalmologists and optometrists that have undergone cataract surgery at Bochner since 2012 have opted for laser surgery versus traditional surgery.

Our top 4 advantages of Laser Cataract Surgery versus Traditional Surgery are as follows:
Reduction or Elimination of Phacoemulsification Energy Traditional phacoemulsification utilizes a probe that vibrates 20,000 times per minute to break up a cataract. This is similar to a jack hammer breaking up cement. In the eye this energy can cause intraocular inflammation and loss of corneal endothelial cells. With the Catalys laser 85% of our cataract cases are now accomplished without any phacoemulsification. In the remaining 15% of cases, the energy from phacoemulsification is greatly reduced. Elimination or reduction of phacoemulsification is possible because of the unique laser fragmentation of the Catalys laser that softens a wide area of the lens.
• Accurate and Consistent Capsulorehexis A 5 mm capsulorehexis performed with the Catalys laser is accomplished in 1.6 seconds. This quick speed is important to decrease the chance of any radial tears that could lead to rupture of the posterior capsule and loss of the nucleus into the vitreous. In over 2,700 eyes treated at Bochner, we have only seen one radial tear.
• Capsulorehexis Centred Over the Visual Axis The Catalys identifies the visual axis and can create a perfectly round capsulorehexis centered over this point. The surgeon then aligns the centre of the implant over the visual axis, which allows for a small amount of anterior capsule covering the implant. Centration of an implant on the visual axis can decrease the induction of higher order aberrations with aspheric and toric implants and improves patient satisfaction with multifocal implants.
• Laser Astigmatism Reduction Astigmatism reduction with laser arcuate cuts has been shown to be more predictable than with a hand held blade. The laser can produce cuts at an exact depth, angle, length, and location. Laser arcuate incisions can be opened by the surgeon at the time of surgery or if combined with a toric implant the incisions can be opened if necessary postoperatively to fine tune the outcome.
Read article by Dr Gifford-Jones in Toronto Sun (July 2017): When You Need Cataract Surgery – Dr Gifford-Jones


 

Keratoconus & Cataract Clinics
- Contact Information -
Our Toronto, Scarborough, and Unionville Offices now offer Keratoconus and Cataract Clinics, in addition to consultations for Laser Vision Correction, Refractive Lens Exchange, and other refractive procedures. Referrals can be mailed, faxed or emailed. Our Oakville Office is limited at this time to general medical ophthalmology referrals.

Toronto
40 Prince Arthur Avenue, Toronto, Ontario M5R 1A9
Phone 416 960 2020
Fax 416 966 8917
Bochner@bochner.com

Scarborough
2941 Lawrence Ave East, Scarborough, ON M1P 2V6
Phone 416 431 7449
Fax 416 439 9523
Scarborough@bochner.com

Unionville
147 Main Street, Unionville, ON L3R 2G8
Phone 905 470 2020
Fax 905 470 2216
Unionville@bochner.com

Oakville
353 Iroquois Shore Road, Oakville, ON L6H 1M3
Phone 905 815 1112
Fax 905 845 7828
Oakville@bochner.com

Understanding Corneal Cross-Linking for the Treatment of Keratoconus

Sunday, January 8th, 2017

Portrait Of Smiling Senior WomanIn April 2016, the United States Food and Drug Administration approved corneal cross-linking for the condition known as keratoconus. Corneal cross-linking has been available in Canada, Europe and other parts of the world for some time now. The Toronto eye doctors at Bochner Eye Institute have been on the leading edge of keratoconus treatment technology — including corneal cross-linking — for many years, and we are some of the most experienced in North America. Read on to learn why other countries such as the U.S. are starting to embrace corneal-crosslinking. (more…)

Lessons Learned in Treatment of Keratoconus by Raymond Stein MD

Tuesday, April 8th, 2014

Experience with CXL, Topography-linked PRK, Intacs, & Phakic IOLs

Over the past years 6 years, we have performed over 4,000 CXL procedures and/or CXL combined with a topographically-linked PRK. In addition, in selected keratoconus patients, we have inserted either intracorneal rings or toric phakic IOLs. Here are our top 10 lessons learned in the surgical management of keratoconus.
1.    CXL is successful in halting keratoconus progression in 98% of eyes. Success rate is higher for corneas that are clear and are less than 60
2.    CXL should be performed on patients as young as possible to halt disease progression and loss of best-corrected spectacle acuity. We have treated patients as young as 10 years of age with corneal stability over a followup period of up to 6 years.

3.    Bilateral CXL should be performed in patients under 25 years of age with unilateral disease. Theoretically the “normal” eye can be followed for signs of disease progression, but unfortunately in some cases the disease can progress rapidly with a loss of best-corrected spectacle acuity. Since keratoconus occurs bilaterally in over 90% of patients we feel it is clinically prudent to perform bilateral CXL in younger patients.

4.    Specialized Riboflavin solutions can induce corneal swelling by at least 100 microns. Preoperatively this means that a 350 micron cornea prior to epithelial removal can usually be treated by CXL. The only corneas that cannot be swollen to any significant extent are those with corneal scars.

5.    The combination of a topographically-linked PRK (TG-PRK) with CXL offers the best chance of improving best-corrected spectacle visual acuity. TG-PRK utilizes preoperative topography maps to guide the excimer laser to flatten steep areas and steepen flat areas. This can result in a decrease in irregular astigmatism and improvement in best-corrected spectacle acuity. Thicker corneas allow for treatment using larger optical zones which have a greater effect. In addition, corneas with less than 10 diopters of difference in the central pupillary area tend to have a greater reduction in irregular astigmatism.

Postop—————————- Preop—————————- Difference Map

In the case above, note the preop inferior to superior difference of around 10 D. This allowed for successful treatment of the irregular astigmatism by flattening the inferior cornea by 4.8 D and steepening the superior cornea by 4.7 D. 

6.    Diagnosis of keratoconus should be made using elevation topography (eg Pentacam), and a careful slitlamp exam. Elevation topography evaluates both anterior and posterior corneal elevation and produces a pachymetry map. Pseudokeratoconus can occasionally be seen using only computerized topography. It is not uncommon for the following conditions to create a pseuokeratoconus pattern: epithelial basement membrane dystrophy (see images below), superficial punctate keratopathy, amiodarone keratopathy, focal corneal scars, and Salzman’s nodular degeneration.

7.    TG-PRK is a more customized approach than intracorneal rings. Usually one or two rings are inserted in the midperiphery. We reserve corneal rings for thin central corneas in which TG-PRK cannot be performed. Rings are typically inserted in advanced cases to allow enhanced contact lens wear.

8.    Best-corrected spectacle acuity can take 6 months to be achieved after CXL or CXL with TG-PRK. It takes time for epithelial maturation to occur. The epithelium can undergo hyperplasia and/or hypoplasia to smooth the corneal surface.

9.    Patients at any age with stable keratoconus may benefit from CXL and TG-PRK to improve best-corrected spectacle acuity. By reducing irregular astigmatism, patients may achieve satisfactory vision with glasses or soft contact lenses.

10.    Stable keratoconus patients with minimal irregular astigmatism, that desire an improvement in uncorrected visual acuity may benefit from a toric implantable contact lens. However, if the refractive error is low then PRK can be performed with limited CXL. This CXL procedure is associated with minimal corneal flattening which results in a more predictable refractive outcome.
Summary

I hope you find these clinical observations of interest in the management of keratoconus. If you have any questions or comments please feel free to contact me at info@Bochner.com.

Sincerely,

Raymond Stein, MD, FRCSC
Medical Director, Bochner Eye Institute
Associate Professor of Ophthalmology, University of Toronto

Topography-Linked PRK – Lessons Learned

Monday, December 16th, 2013

Value in Keratoconus, LASIK or PRK Complications, Irregular Astigmatism, and Post-RK

We have had a positive experience in performing topography-linked PRK (TG-PRK) for keratoconus, post-LASIK or PRK complications, irregular astigmatism from corneal scars, and post-RK. This technology has demonstrated significant value in improving best-corrected visual acuity and quality of vision.

Technique

The preoperative technique involves the capture of 8 consistent Scheimpflug images utilizing the Oculyzer, a device which is similar to the Pentacam. These images are then digitally transferred to the Allegretto 400 KHz to plan our customized laser ablation. The procedure involves flattening steep areas and steepening flat areas to improve the regularity of the corneal surface.

The surgical technique involves a 50-micron PTK ablation to remove the corneal epithelium. In cases of keratoconus, the corneal epithelium tends to be thinner over the cone compared to the base, and thus the 50-micron laser ablation tends to remove a thin amount of the protruding cone. This treatment is followed by a TG-PRK. In keratoconus, we try to limit the stromal laser ablation to 50 microns. Large optical zones of 6.0 or 6.5 mm, are typically associated with a greater effect and stability compared to smaller zones. The optical zone chosen depends on the preoperative corneal thickness and the degree of corneal irregularity. Corneas with a minimum thickness of 450 microns or greater typically allow for the use of larger optical zones. However, if there is a very high dioptric difference across the cornea then smaller zones may be required to minimize tissue removal.

Case Example #1

76 year old male with a corneal scar that induced significant central flattening and irregular astigmatism. A TG-PRK was performed that resulted in BCSVA improving from 20/80 to 20/30. Note the difference map below which resulted in 7.9 D of steepening centrally and 6.4 D of flattening supronasally.

Case Example #2

28 year old female with keratoconus that underwent TG-PRK and CXL on Dec 3, 2012. Examination 11 months postop showed an improvement in BCSVA from 20/40 to 20/25. Pentacam maps showed the inferior steepening to be resolved and replaced with a symmetric bow-tie pattern of astigmatism.

I hope this information is of help to you in understanding the clinical significance of a topographically-linked laser ablation. If you have any questions or comments please feel free to contact me at info@Bochner.com.

Learn more here
Sincerely,

Raymond Stein, MD, FRCSC
Medical Director, Bochner Eye Institute
Associate Professor of Ophthalmology, University of Toronto

FAQS on Corneal Crosslinking by Dr Raymond Stein- Toronto Eye Surgeon

Friday, March 16th, 2012

Corneal Crosslinking – Frequently Asked Questions

Is Corneal Crosslinking (CXL) a new treatment for keratoconus?
CXL was introduced in Canada by the surgeons of the Bochner Eye Institute over 4 years ago. In Europe, where the procedure was pioneered, it has been performed for over 14 years ago. There are many long-term studies that demonstrate the efficacy and safety of the procedure.

What is the main goal of CXL?
The purpose of the treatment is to strengthen corneas so as to prevent progressive bulging and thinning that can interfere with vision. With a stronger and more stable cornea the risk of requiring a corneal transplant is practically eliminated.

What is the success rate of CXL?
At the Bochner Eye Institute over 3,000 eyes have been treated with CXL over the past 4 years. This is more than any other centre in the world. Patients have travelled from all over North America. The success rate at preventing progressive bulging and thinning has been over 98%.

Can CXL be repeated?
In rare cases (less than 2%) where CXL is not successful in stabilizing a cornea, a repeat treatment can be performed. There is no charge for this procedure at the Bochner Eye Institute.

Is there an ideal age for CXL?
Usually, the younger the patient the greater the chance of preserving vision with CXL. Patients treated at the Bochner Eye Institute have ranged in age from 10 to 60 years age. With treatment, the corneal contour is preserved, and therefore it is best to have CXL when the shape is only mildly distorted. Patients with advanced disease can have CXL but the vision may be less than ideal with glasses or soft contact lens necessitating the use of a rigid contact lens.

Are some keratoconus patients not good candidates for CXL?
Patients must have satisfactory corneal thickness for the procedure to be performed. A thickness of 400 microns is required prior to the ultraviolet light application. Corneas with a thickness between 320 microns and less than 400 microns can usually be treated by using specialized hypotonic drops to swell the cornea to 400 microns or greater prior to the ultraviolet light application. Also, corneas with significant central scarring that interferes with vision are not good candidates for CXL.

Can vision be improved with CXL?
Although the main goal of CXL is to stabilize the cornea, 60% of patients actually have an improvement in their vision. This is due to the fact that the corneal surface becomes less irregular with CXL as the steep areas are flattened and the flat areas are steepened.

How is the procedure performed?
The procedure is divided into 3 steps. Most patients find the procedure very easy and are comfortable. Anesthetic drops are instilled, which numbs the surface of the eye, and makes the procedure pain free. The first step of the procedure is the removal of the central corneal epithelium. A very gentle brush is used to polish away the soft cells of the front of the cornea referred to as the epithelium. The second part of the procedure is the instillation of specialized drops containing Riboflavin. Drops are typically used for 20 minutes. The third part of the procedure is the use of ultraviolet light, which is typically used for 10 minutes.

Why does the ultraviolet light treatment time vary from clinic to clinic?
The original treatment protocol in Europe was the use of ultraviolet light for 30 minutes at an energy level of 3mw/cm2. With the development of new CXL devices the energy level can be increased which shortens the treatment time said Dr Raymond Stein.

Can the corneal epithelium be left intact or does it have to be removed?
The long-term clinical studies have shown outstanding results when the epithelium is removed prior to CXL. New techniques are being developed to perform a transepithelial CXL approach in which the epithelium is left intact. It is essential for the success of this technique that the Riboflavin drops penetrate an intact epithelium to reach the deeper layers of the cornea in a high enough concentration. Early results with this technique are encouraging but we do not know the long-term results.

What is required after the treatment?
Immediately after the procedure a soft bandage contact lens is inserted which is worn for approximately 5 days. This allows enhanced comfort and promotes healing of the corneal epithelium. An antibiotic drop is used for 5 days and a steroid drop is used for 2 weeks. Artificial tears can be used as needed for comfort.

Is the vision better immediately after the procedure?
Usually the vision is slightly blurrier during the first month and then gradually improves. The blurred vision is related to the healing time of the corneal epithelium. Initially when the epithelium becomes intact it tends to be somewhat rough. With times it undergoes thickening and thinning in different areas to smooth the corneal contour.

How do I know if the treatment is successful?
Repeat corneal mapping is performed to demonstrate corneal stability or flattening. The mapping is typically performed at 4 to 6 months postoperatively and then annually. Sophisticated mapping techniques can evaluate both the front and back surfaces of the cornea to determine stability, improvement, or progression.

What are the potential complications of the treatment?
The complication rate is extremely low with CXL. The risk of infection is rare. In fact ultraviolet light can be used to kill bacteria and parasites in patients with corneal infections. Occasionally there is a delay in the healing of the corneal epithelium, which can delay the return of best vision.

When can I start wearing contact lenses?
After the procedure it is best to wait 2 weeks before returning to contact lens wear. If you have never worn contact lenses and would like to start lens wear it is best to wait at least one month before a consistent refraction can be obtained and lenses fitted.

How can I improve my vision so that I do not need rigid contact lenses?
There are two surgical options to reduce the irregular astigmatism so that you can see better without rigid contact lenses. An intracorneal ring (Intacs) can be performed in which one or two rings are inserted into the cornea to flatten steep areas. The other option is a topographically-linked photorefractive keratectomy (PRK) in which an excimer laser is used to flatten the steep cornea and steepen the flat cornea to enhance vision. Both these procedures can be performed at the same time as CXL or at later date.

More about Dr Raymond Stein

Dr. Raymond Stein Lectures On New Innovative Treatments

Monday, November 14th, 2011

Dr. Raymond Stein was an invited guest speaker to the Vision Institute’s annual meeting in Toronto on November 4, 2011. The title of his presentation was “The Future of Cataract and Refractive Surgery”. Dr. Stein discussed some of the new innovative treatments such as Laser Cataract Surgery, Corneal Inlays for presbyopia, Corneal cross-linking combined with topographic laser ablations, and Microwave technology for keratoconus. The audience was over 300 eye-care professionals.

Dr. Raymond Stein’s Session Entitled “Ask the Expert”

Monday, November 14th, 2011

Dr. Raymond Stein was invited to speak at the American Academy of Ophthalmology’s annual meeting in Orlando on October 21, 2011. His session was titled “Ask the Expert” and he spoke on the subject of Corneal Cross-Linking in Keratoconus.

Background of Raymond Stein

Thursday, May 5th, 2011

Dr. Raymond Stein, MD, FRCSC, is an esteemed global leader in refractive surgery who has successfully performed more than 80,000 vision correction procedures. He obtained his medical degree at the University of Toronto Medical School, where he currently serves as an Assistant Professor of Ophthalmology. Dr. Stein completed his ophthalmology residency at the world-renowned Mayo Clinic and a cornea and external disease fellowship at the prestigious Willis Eye Hospital in Philadelphia. He serves as the Medical Director of the renowned Bochner Eye Institute in Toronto.

Raymond Stein has established himself as an expert and pioneer in refractive and implant surgery and was the first surgeon in all of Canada to perform corneal cross linking with Riboflavin for keratoconus and ectasia. He was also the first eye surgeon in Canada to implant the ReSTOR and Tetraflex IOLs for improved distance, intermediate and near vision. Dr. Stein was the first surgeon in Canada to use the IntraLase IFS femtosecond laser for creation of the LASIK corneal flap.

Dr. Raymond Stein is frequently invited to lecture at medical conferences throughout the world. He has authored numerous published articles, more than 15 book chapters and books on various subjects pertaining to refractive surgery. In fact, Dr. Stein is the author of the first clinical textbook on laser vision correction for instruction on advanced surgical techniques.

As a testament to his prolific career and unsurpassed surgical skills, Dr. Stein was chosen to serve at the Chief Eye Surgeon for W Network’s “Style by Jury,” a popular makeover television show in Canada. He is also the editor of the prestigious scientific journal “Clinical and Surgical Ophthalmology.”

In recognition of his accomplishments in refractive surgery, Dr. Stein has been honored with numerous prestigious awards from both national and international professional organizations, including the American Academy of Ophthalmology, the International Intraocular Implant Club and the Contact Lens Association of Ophthalmologists. He has also served as the President of prestigious Canadian Society of Cataract and Refractive Surgery.
Dr. Stein is the Chief of Ophthalmology at the Scarborough Hospital in Toronto and Cornea Consultant at the Mount Sinai Hospital

Education:

Undergraduate:

University of Pennsylvania, Wharton School

1975-1977

 

Medical School:

Doctor of Medicine

University of Toronto Medical School

1978-1982

 

Residency:

Mayo Clinic

1983 -1986

 

Fellowship Training:

Willis Eye Hospital, Philadelphia

1986-1987

Experience:

Bochner Eye Institute

Medical Director, Eye Surgeon

1997- Present

 

Scarborough Hospital, Toronto

Chief of Ophthalmology, Ophthalmologist

1987- Present

 

Mount Sinai Hospital

Cornea Consultant, Ophthalmologist

1989 – Present

 

University of Toronto Medical School

Assistant Professor of Ophthalmology

Professional Affiliations:

Contact Lens Association of Ophthalmologists

Wills Eye Hospital Alumni Association
American Academy of Ophthalmology

Fellow of the Royal College of Surgeons
Mayo Clinic Alumni Association

Ontario Medical Association

International Society of Refractive Surgery

American Society of Cataract and Refractive Surgery
Canadian Society of Cataract and Refractive Surgery

International Implant Club

Academy of Ophthalmic Education

Raymond Stein, MD, Honors and Awards:

1987 – 1988 Award for most outstanding article of the year published in the University of Toronto Medical Journal, titles “Lifesaving Ocular Signs.”

1990- 1991 Award for outstanding teaching, Ophthalmology Residents Research Day, University of Toronto, Toronto, Ontario, April 1991.

1991 – 1992 Nominated for Atkinson award, outstanding undergraduate teaching, University of Toronto.

1993 – 1994 Award for outstanding undergraduate and post graduate teaching, Mount Sinai Hospital, University of Toronto.

1997 Honor award of American Academy of Ophthalmology

1997 Honor award of Contact Lens Association of Ophthalmologists

1998, ‘99, ’00, ’01, ‘02
Best paper of session, American Society of Cataract and Refractive Society

2001 Awarded membership into International Intraocular Club

2003 Best paper of session, International Society of Refractive Surgery

Books:

1.      Raymond M. Stein, Bernard J. Slatt, Harold A. Stein. A Premier in Ophthalmology: A Textbook for Students. Mosby.

2.       Raymond M. Stein, Melvin I. Freeman, Harold A. Stein. The Ophthalmic Assistant: A Text for Allied and Associated Ophthalmic Personnel. Mosby, 2006.

3.      Raymond Stein, Harold A. Stein, Melvin I. Freeman, Lynn D. Maund. Residents Contact Lens Curriculum Manual. Mosby.

4.       Raymond  Stein, Harold A. Stein, Melvin I. Freeman, Lynn D. Maund. Contact Lenses: Fundamentals and Clinical Use. Slack Incorporated, 1996.

5.      Raymond Stein, Bernard J. Slatt, Harold A. Stein, Melvin I. Freeman. Fitting Guide for Rigid and Soft Contact Lenses: A Practical Approach. Mosby, 2002. 

6.      Raymond Stein, Harold A. Stein, Albert Cheskes. Laser Vision Correction: Welcome to a World Without Glasses or Contact Lenses.

7.      Raymond Stein, Harold A. Stein. Management of Ocular Emergencies. Medicöpea International.

8.      Raymond Stein, Bernard J. Slatt, Harold A. Stein. Ophthalmic Terminology: Speller and Vocabulary Builder. Mosby, 1991.

9.      Editor. Raymond M. Stein. Proceedings of the External Eye Meeting. Medicöpea International, 1995.

10.  Raymond M. Stein, Harold A. Stein, Albert Cheskes. The Excimer Fundamentals and Clinical Use. Slack Incorporated, 1997.

Peer-Reviewed Research Papers and Articles:

1.      Raymond M. Stein. Laser vision correction: 20 years of personal experience. ASCRS EyeWorld.

2.      Raymond M. Stein. Corneal Collagen Cross-Linking with Riboflavin (C3-R) and other Surgical Options in the Management of Keratoconus. Academy of Ophthalmic Education (AOE).

3.      Raymond M. Stein. Ten Pearls for Treating Hyperopic Astigmatism. Refractive Eyecare for Ophthalmologists.

4.      Raymond Stein. Techniques for Advanced Surface Ablation. Refractive Eyecare for Ophthalmologists.

5.      Raymond M. Stein. Phakic Implants Can Expand a Refractive Surgery Practice. Refractive Eyecare for Ophthalmologists.

6.      Raymond M. Stein. Patients to Avoid Personality Screening. Refractive Eyecare for Ophthalmologists.

7.      Raymond M. Stein. Keratoma-Assisted ASA. Refractive Eyecare for Ophthalmologists.

8.      Raymond M. Stein. Defining Safety in Keratome Technology. Refractive Eyecare for Ophthalmologists.

9.      Raymond M. Stein. Clinical Experience with the Allegretto Wave in Custom and Standard Treatments. Refractive Eyecare for Ophthalmologists.

10.  Raymond M. Stein. Advances in Refractive Surgery. Ophthalmology Rounds.

Raymond Stein Reviews

Dr. Raymond Stein Speaks at ASCRS

Thursday, April 7th, 2011

Dr. Raymond Stein was an invited guest speaker to the annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS) in San Diego on March 28, 2011. He presented the results from the Bochner Eye Institute of Corneal Collagen Crosslinking with up to 3.5 years of follow-up. None of the treated patients have shown any progressive ectasia. Crosslinking has been shown to be a major advance in the treatment of keratoconus, pellucid marginal degeneration, and ectasia after refractive surgery. The surgeons at the Bochner Eye Institute have been pioneers with this technology in North America. To learn more about Raymond Stein, MD, & Bochner Eye Institute, please call (416) 960-2020.

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Computerized Topography to Rule-Out Keratoconus Prior to LASIK

Friday, January 21st, 2011

Dr Raymond Stein of the Bochner Eye Institute wrote the following clinical update. We hope you find it of interest.

Keratoconus is a well-recognized contraindication to LASIK. The creation of a corneal flap and removal of tissue by an excimer laser can weaken a cornea making it structurally compromised. This can lead to corneal instability with progressive ectasia characterized by steepening and thinning. Although there are a variety of clinical signs of keratoconus the use of computerized topography and pachymetry usually allows for the detection of the earliest stages of keratoconus. The most advanced topography units measure both curvature, elevation, and pachymetry. The Pentacam is our unit of choice at Bochner.

We typically make the diagnosis of keratoconus when one or more findings are present:

1. Inferior steepening of greater than 1.5 Diopters compared to superior cornea.

2. Elevation of the posterior cornea of greater than 17 microns compared to a best-fit sphere.

3. Elevation of the anterior cornea of greater than 21 microns compared to a best-fit sphere.

4. Central steepening of greater than 49 Diopters.

5. Steepest corneal location associated with thinning of less than 500 microns.

6. Advanced clinical signs include corneal iron deposition at the base of the cone, Vogt’s striae or stress lines, and apical scarring.

In addition to the clinical findings above we are reluctant to perform LASIK if there is an immediate family history of keratoconus.

Careful preoperative evaluation prior to laser vision correction can greatly reduce the risk of corneal ectasia.