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Inside Eyetube.net | Jan 2013

From Slipknots to Lasers

Surgeons provide step-by-step analyses of some of the most watched videos on Eyetube.net.

Alan N. Carlson, MD

Adjustable-tension slipknots are certainly not new, but there is resurgence in interest among corneal and refractive surgeons and their trainees. In the 1970s, Clifford Terry, MD, developed the Terry slipknot (Figure 1) to enhance the capabilities of the Terry keratometer (no longer available), which was designed to optimize suture tension and manage astigmatism. I had the benefit of learning about this knot during my first year of residency under Jared Emery, MD, and Douglas Koch, MD. This suture technique, which I demonstrate in my video, achieves consistent and controlled tension in patients who need multiple sutures for procedures such as penetrating keratoplasty or deep anterior lamellar keratoplasty and in cases of penetrating and perforating traumatic lacerations. Furthermore, this is helpful in young children who are at risk of amblyopia and would benefit from speedy visual recovery.

According to Dr. Terry, there are two ways to tie this knot. The first is to hold both ends of the forceps in the left hand. The forceps in the right hand go over the top of both arms pointed toward the incision. The forceps then go around and under both suture arms to grab the short end of the suture, which when pulled through forms a knot around the other arm. To increase friction, the top and bottom of the knot are simultaneously pulled. The tension at the incision is then titrated by controlling the tension of the knot. This step is accomplished by pulling the end without the knot to tighten and the end with the knot to loosen.

The other way to create the slipknot is to cross the sutures. In this variation, the forceps in the right hand go between the sutures pointed toward the incision. Next, the forceps in the right hand go under the lower suture and then around it to grasp the end and form the knot. Multiple temporary tension sutures can be adjusted under keratoscopic control for consistent and symmetric suture tension. The final throw locks the suture at the desired tension, and the knot is buried.

Much of our present-day surgery has become sutureless, but it is still valuable to have this technique in our armamentarium for cases requiring sutures in which early visual rehabilitation is desired.

Alan N. Carlson, MD, is a Professor of Ophthalmology and Chief of Corneal and Refractive Surgery at Duke Eye Center in Durham, North Carolina. He may be reached at tel: +1 919 684 5769; e-mail: alan.carlson@duke.edu.

Damien F. Goldberg, MD

Although the role of the femtosecond laser in cataract surgery is evolving, in my video I share eight pearls for early adoption.

No. 1. Practice verbal anesthesia.
Verbally counsel your patient to look into the laser. It is crucial with first- and second-generation suction rings to obtain good centration when the ring is docked onto the eye. Therefore, the patient must be reminded to look straight into the laser, not up at the surgeon. I also remind my patients to remain relaxed. It is important to avoid Bell phenomenon; sometimes, 1 mg midazolam with 25 mg of fentanyl administered by the anesthesiologist is helpful.

No. 2. Achieve centration and suction. As with the IntraLase femtosecond laser (Abbott Medical Optics Inc.), head tilt and eyelid exposure are important to achieve good centration on the eye and suction. Move the patient’s eyelashes out of the way and tape the extra dermatochalasis from the upper or lower eyelids if necessary.

No. 3. Measure the pupil size before the case. When suction occurs, pupil size will decrease. The smallest capsulorrhexis that can be generated with the LenSx Laser (Alcon Laboratories, Inc.) has a circumference treatment of 4.3 mm; the laser will treat only 0.5 mm smaller than the pupil. My preference is a capsulorrhexis of 5.1 mm for standard, toric, and multifocal IOLs and 6.0 mm for accommodating IOLs. By measuring the pupil size before starting a case, I have not had to cancel a surgery because of poor dilation. I counsel patients with intraoperative floppy iris syndrome ahead of time.

No. 4. Be aware of the three-plane corneal incision. I make incisions about 30º to 45º away from the flat plane. The femtosecond laser designs such precise three-plane incisions that the incisions are at a steeper angle, about 80º to 90º. If using a Slade spatula or the Sinskey hook, aim downward to open the incisions, avoiding generating article planes in the corneal stroma.

No. 5. Double-check the capsulotomy. A laser-generated capsulorrhexis will do a better job than a manually created one at obtaining the effective lens position. Sometimes, however, the laser can generate adhesions. I recommend using a cystotome or Utrata forceps to confirm that the capsulotomy is free of tags and adhesions.

No. 6. Scrape the cortical material before I/A. A laser capsulorrhexis will be generous and deliver laser shots superior and posterior to the capsule and into the cortical material. There are no adverse side effects of this treatment. The capsulorrhexis, however, is cleaved so cleanly that purchasing the cortex with the I/A port can be challenging. Before I perform I/A, I use the Shepherd Capsule Polishing Curette (Walcott Rx Products) or a cortex club (Epsilon USA) and scrape around the cortical material before the nucleus is removed. Roughing the cortical material allows greater cortical purchase with the I/A tips, making removal easier.

No. 7. Release built-up gas bubbles. Capsular rupture during hydrodissection and hydrodelination has been a concern.1 The laser generates gas that can become trapped in and behind the lens fragments. I recommend careful hydrodissection of the fragments or complete cracking of the nucleus to release the build-up of gas bubbles.

No. 8. Confirm residual astigmatism. I open limbal relaxing incisions with a Slade spatula or a Sinskey hook and check residual astigmatism with the Optiwave Refractive Analysis System (WaveTec Vision) before opening incisions the next day in the office.

Section Editor Damien F. Goldberg, MD, is in private practice at Wolstan & Goldberg Eye Associates in Torrance, California. Dr. Goldberg states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +1 310 543 2611; e-mail: goldbed@hotmail.com.

  1. Roberts RV, Sutton G, Lawless MA, et al. Capsular block syndrome associated with femtosecond laser assisted cataract surgery. J Cataract Refract Surg. 2011;37:2068-2070.

Arun C. Gulani, MD

PRK can be performed on anterior corneal scars in patients who have the potential for good BCVA. In my experience of more than 10 years performing PRK on corneal scars, I have found that that most herpetic scars become part of the cornea. My corneal scar algorithm is part of my original 5S system.1-4 My video begins with rapid movements to remove the epithelium in an atraumatic fashion, leaving the scarred area for last. I approach the scarred area from the periphery, literally raising the edges of the scar to determine whether this is an on-cornea (layered anterior to the cornea; Figure 2) or in-cornea (one that has blended with the rest of the cornea; Figure 3) scar. The scar in the video is in-cornea, and I approach it as I would any other refractive error, regardless of its opacity. Next, I perform PRK with mitomycin C. Upon completion of the laser procedure and following application of balanced salt solution, the ring light reflex on the cornea, which was D-shaped, can be seen as a perfect circle. This reflex directly correlates to the improvement in the visual quality of the patient’s eye. This approach provides patients with anterior corneal scars, otherwise headed for interventional surgery, with a stable cornea to undergo vision correction. This approach also helps to correct complications of laser vision surgery that resulted in corneal scars and haze.

Arun C. Gulani, MD, is Director of the Gulani Vision Institute in Jacksonville, Florida. He may be reached at tel: +1 904 296 7393; e-mail: gulanivision@gulani.com.

  1. Gulani AC. Corneoplastique. Techniques in Ophthalmology. 2007:5(1);11-20.
  2. Gulani AC. A new concept for refractive surgery: corneoplastique. Ophthalmology Management. 2006;10(4):57-63.
  3. Gulani AC. Corneoplastique. Video Journal of Ophthalmology. 2007;23(3).
  4. Gulani AC. Corneoplastique. Video Journal of Cataract and Refractive Surgery. 2006;22(3).

Sunil Shah, MBBS, FRCOphth, FRCS(Ed), FBCLA

I present the use of the Lentis Comfort Toric IOL (Oculentis GmbH) in clear lens extraction for a patient with high myopia, astigmatism, multiple sclerosis, and a central scotoma from previous optic neuritis. The patient was having increasing difficulty managing contact lenses and was concerned about the long-term need for spectacles. I implanted the Lentis Comfort Toric IOL with a 1.50 D add. Fine near vision would not be possible because of the central scotoma, but the Comfort lens offered the smallest chance of experiencing dysphotopsia and loss of contrast sensitivity.

I begin by marking the 9-, 12-, and 3-o’clock positions to ensure the lens is oriented correctly, with the long axis running from the 6- to 12-o’clock positions (90º). Next, I make an incision at 90º with a 2.75-mm keratome and a small paracentesis at 180º. Using a cystotome, I create the capsulorrhexis. During hydrodissection, I lift the capsule to strip the lens from it. After hydrodelineation, the lens is aspirated without need for phacoemulsification, and I carefully clean the capsular bag, inject the lens, and nudge the trailing edge of the haptic plate so that it lands straight in the capsular bag. I check IOL alignment before and after removing the ophthalmic viscosurgical deice, reexamining the lens orientation against the ink marks. I inject intracameral cefuroxime after I hydrodissect the wound.

Sunil Shah, MBBS, FRCOphth, FRCS(Ed), FBCLA, is an Honorary Professor at the School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland; Visiting Professor at the School of Life & Health Sciences, Aston University, Birmingham, United Kingdom; Director, Midland Eye Institute, Solihull, United Kingdom; and Consultant Ophthalmic Surgeon, Birmingham & Midland Eye Centre, Birmingham, United Kingdom. Professor Shah states that he is a consultant to Topcon Europe. He may be reached at tel: +44 1217112020; fax: +44 1217114040; e-mail: sunilshah@doctors.net.uk.

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