Article originally published on Healio, Nov. 16, 2021.
Corneal allogenic intrastromal ring segments have been described by Jacob and colleagues for the treatment of keratoconus.
They consist of semicircular pieces of donor corneal stroma that may be surgically implanted to flatten, stiffen and stabilize the shape of the recipient cornea.
Early corneal allogenic intrastromal ring segments (CAIRS) protocols used donor segments prepared immediately before implantation, at the time of the surgery. However, because this process involves multiple steps, it may add significantly to the overall procedure time. In addition, any problems encountered during segment creation could jeopardize the ability to complete the operation. Therefore, it may be advantageous to prepare the donor material in advance.
Similar considerations have inspired the recent utilization of so-called “patient-ready” tissue for Descemet’s membrane endothelial keratoplasty, ie, donor endothelium that has been prestripped, prestained and preloaded. Since this concept was introduced in 2016, studies have demonstrated robust stain retention and tissue viability, with surgical outcomes comparable to those in which the tissue is prepared intraoperatively. Patient-ready tissue may also facilitate the uptake of DMEK by novel surgeons by diminishing the anxiety and risks associated with graft preparation.
To date, we have performed CAIRS in 16 eyes of 15 patients with keratoconus using precut, prestained tissue. These patient-ready segments are prepared within an eye bank setting 48 to 72 hours before surgery. A donor corneoscleral button is debrided of epithelium and endothelium using a surgical sponge and then mounted on a Teflon cutting block. A dedicated CAIRS trephine (Jacob CAIRS trephine, Madhu Instruments) is used to create a circular tissue ring that is bisected via surgical knife into two semicircular segments. The option also exists to supply it as a full ring to allow customization of arc length by the surgeon. Both segments are submerged in 0.06% trypan blue (VisionBlue, DORC International) for 3 minutes until a dark blue tissue stain is obtained and then replaced in storage solution and photographed (Figure 1a). At the time of surgery, the segments are removed from storage, irrigated with saline, dehydrated atop a surgical sponge and implanted (Figure 1b).
Since transitioning to patient-ready CAIRS, no additional intraoperative or postoperative complications have been experienced. As with prestripped and prestained DMEK grafts, the tissue retains its blue stain throughout the duration of the procedure but fades completely by several days postoperatively.
Advantages of patient-ready CAIRS may include reduced surgical time, flattened surgical learning curve and increased consistency of product. As a result, this may become a preferred option for tissue preparation, especially for surgeons starting with the technique.
Jacob S, et al. J Refract Surg. 2018;doi:10.3928/1081597X-20180223-01.
Parekh M, et al. Am J Ophthalmol. 2016;doi:10.1016/j.ajo.2016.03.048.
Parker JS, et al. J Cataract Refract Surg. 2021;doi:10.1097/j.jcrs.0000000000000316.
Parker JS, et al. J Cataract Refract Surg. 2021;doi:10.1097/j.jcrs.0000000000000582.
Potts LB, et al. Cornea. 2020;doi:10.1097/ICO.0000000000002400.
Zafar S, et al. Clin Ophthalmol. 2019;doi:10.2147/OPTH.S212871.
For more information:
Hudson Tate, David Blackburn and Jack S. Parker, MD, PhD, can be reached at Parker Cornea, 700 18th St. South, Suite 503, Birmingham, AL 35233; emails: firstname.lastname@example.org; email@example.com; firstname.lastname@example.org.
https://parkercornea.com/wp-content/uploads/2021/12/Prestained.png4381122Parker Corneahttps://parkercornea.com/wp-content/uploads/2021/12/Logo-01.pngParker Cornea2021-11-16 16:36:092022-01-17 15:52:48Precut, prestained tissue segments may be advantageous in keratoconus surgery
Article originally published on Healio, July 9, 2021.
Pinhole pupilloplasty has helped change many lives. The idea of small-aperture optics is not only simple but advantageous in cases of high astigmatism.
Jack S. Parker, MD, PhD, of Parker Cornea and the Netherlands Institute for Innovative Ocular Surgery (NIIOS), is my guest columnist this month, and he will explain with his co-author how to master pinhole pupilloplasty (PPP).
The terminology of pinhole pupilloplasty was suggested to me by David Chang, and I will always be grateful to him for coming up with such a suitable name. PPP can be done with any technique of iris suturing. Since McCannel started iris suturing and then Siepser took it to another level, so many others have pioneered in this area. Ogawa brought in the cerclage, and Ike Ahmed brought in the McAhmed suturing technique. Priya Narang helped pioneer single-pass four-throw pupilloplasty, for which I am indebted. The four-throw technique basically got us out of the locking system that was being used in all the iris suturing techniques. This made the whole surgery of iris suturing easy and possible by any surgeon. When we perform PPP, we generally use the single-pass four-throw pupilloplasty technique, although one can use any technique of their choice.
Pinhole pupilloplasty (PPP) was recently described for the treatment of severe corneal astigmatism. Pinhole apertures block stray distorted light rays and confer enhanced depth of focus. For this reason, pinhole IOLs are readily available in many places globally but not in the United States, where the FDA has yet to approve them. Therefore, Dr. Agarwal published a technique for recreating the pinhole aperture naturally by suturing the iris to produce a pinhole-sized pupil.
Initial publications with this technique are impressive: Eyes with more than 10 D and even more than 20 D of irregular (often fluctuating or unstable) astigmatism from prior penetrating keratoplasty or radial keratotomy are improved, in many cases achieving better than 20/40 (0.5) uncorrected vision. Further, PPP is cost-effective, uses already widely available and FDA-approved materials (suture), and is easily reversible without return to surgery, for example, by lasering the iris stitches, which can be done in clinic.
These advantages inspired us to start with PPP, and here, we describe some difficulties and insights acquired during our learning curve with the procedure.
1. Size is important. Ideal for most patients is 1.5 mm. Any larger, and the benefit of the pinhole aperture is reduced (Figure 1a). If smaller, visual acuity can become limited by diffraction (Figure 1b). Consider erring on the side of “too small” because the pupil may be subsequently enlarged via YAG laser postoperatively.
2. Centration is important, too. The pinhole aperture should be fashioned around the first Purkinje image as a reference marker. A decentered pinhole-sized pupil is as optically offensive as a decentered multifocal IOL and reliably results in suboptimal visual outcomes (Figure 2).
3. Use bracketing sutures. Both sides of the pupil must be sutured. Otherwise, when the preoperative or intraoperative miotic agent wears off, the patient will experience asymmetrical re-dilation (Figure 3).
4. Suturing is facilitated by micro-grasping forceps. Dr. Agarwal originally described a “railroad technique” in which the suturing needle passes through the distal iris, a 26-gauge needle passes through the proximal iris, and the two are docked together and withdrawn from the eye. However, the 26-gauge needle often creates large needle track holes in the proximal iris, which are cosmetically and perhaps functionally detrimental (Figure 4a). So, we have replaced the 26-gauge needle with 25-gauge micro-grasping forceps, which may be used to hold and withdraw the suturing needle from the eye (Figure 4b). At present, Dr. Agarwal uses a 30-gauge needle, which is smaller and less traumatic to the iris.
5. Consider combining PPP with phacoemulsification and IOL implantation. Best for surgeons starting with PPP are phakic eyes also needing cataract surgery. In such cases, the phaco alone will likely render some benefit, obviating the need to execute the perfect PPP to satisfy patient expectations.
PPP has been a significant addition to our practice because, for the first time, we are able to offer some solution for patients with severe, irregular, fluctuating astigmatism (for example, from prior RK or PK) who are otherwise unable or unwilling to tolerate hard contact lenses. The procedure is quick and straightforward. It can be incorporated across most settings with ease as there is no need for specialized equipment.
Further, the operation is easy to recommend because, from their personal experience with eye exams, patients intuitively understand the visual improvement that they derive from pinholes. For doubters, a short course of topical pilocarpine may be tried preoperatively. Then, patients may be asked whether the resulting miosis improved their vision and, if so, whether they would like to have this effect recreated surgically.
PPP has predictable results that can be easily demonstrated preoperatively, allowing patients to have a tangible understanding and expectation of the procedure. It is also safe, reversible and highly effective for patients with few other options. After a short learning curve, it has become a regular surgical procedure at our practice, and most of our patients have reported great improvements without complications. As we continue to refine our technique, we expect even greater success with PPP.
For more information:
Jack S. Parker, MD, PhD, can be reached at Parker Cornea, 700 18th St. South, Suite 503, Birmingham, AL 35233; email: email@example.com.
Edited by Amar Agarwal, MS, FRCS, FRCOphth, director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Agarwal is the author of several books published by SLACK Books, sister company of Healio publisher Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; email: firstname.lastname@example.org; website: www.dragarwal.com.
AMELIA ISLAND, Fla. — In this video from Cataract Surgery: Telling It Like It Is, Jack S. Parker, MD, PhD, discusses the importance and difficulty of knowing what to say to patients following cataract surgery that does not go as planned.
Recently, Descemet’s membrane endothelial keratoplasty has emerged as the preferred treatment for corneal endothelial dysfunction because it affords the best visual acuity with the lowest risk for various complications.
As the operation has grown more popular, various innovations to the technique have been introduced, including so-called “patient ready” DMEK, featuring “pre-stripped, stamped and stained” tissue. Despite the added convenience, “patient ready DMEK” necessitates the graft diameter to be specified in advance.
This obligation to specify in advance may result in a one-size-fits-all solution in which surgeons commonly use a standard/default graft size for (nearly) all patients. However, this default may occasionally produce undersized grafts, which inadequately treat the patient’s endothelial dysfunction (Figure 1a), or oversized grafts, which are more difficult to unfold and potentially prone to detachment (Figure 1b).
Rather than default sizes, it therefore may be desirable to tailor graft diameters for individual patients. However, this would require a method for reliably and conveniently measuring dimensions of the recipient eye before surgery. To this end, we propose a simple strategy — namely, using the preoperative horizontal corneal white-to-white (HWTW) provided by the Pentacam HR (Oculus).
The Pentacam HR employs rotating Scheimpflug imaging to obtain 50 images of potentially 138,000 corneal locations, thereby generating data for the HWTW, which may be used to calculate the graft diameter necessary to cover the recipient posterior corneal surface.
Recently, we retrospectively evaluated our last 74 consecutive DMEK operations using “patient ready” tissue. Then, we compared our subjective surgical impression of the size of the graft (well sized vs. too big vs. too small) against the preoperative Pentacam HR measurements of HWTW to generate a graft sizing nomogram, which is presented in the table.
Corneal HWTW (mm)
Graft diameter (mm)
10.5 to 10.75
10.75 to 11
11 to 11.25
11.25 to 11.5
11.5 to 11.75
11.75 to 12
12 to 12.25
In our cohort of 74 eyes, the median HWTW was 11.65 mm, with 25% of eyes falling below 11.3 mm and 25% above 11.8 mm. For the median HWTW, a graft diameter of 8.25 mm appeared to be the optimal size (ie, could be unfolded easily and applied to the posterior cornea with a small peripheral rim of unstripped host Descemet’s membrane without overlapping). For eyes with HWTW higher or lower than the median value, the graft diameter should be adjusted, as described in the table.
Since implementing this nomogram, our incidence of mis-sized grafts has significantly decreased, resulting in easier and more enjoyable operations and fewer postoperative detachments. By incorporating more data points or additional patient anatomic parameters (for example, anterior chamber depth), it may be possible to further refine this nomogram and to provide detailed recommendations about graft sizing in difficult eyes (for example, eyes with very shallow or deep anterior chambers).
Article originally published on Healio, Nov. 16, 2021.
Office-based surgery exploded into the popular consciousness with the publication of the 2015 Kaiser study, reporting more than 21,000 cataract operations performed safely and effectively in clinic minor procedure rooms.
Since then, office-based surgery (OBS) suites have trickled into existence throughout the United States. These have primarily been designed for cataract surgery, but for the past year, we have also been performing OBS Descemet’s membrane endothelial keratoplasty.
OBS DMEK offers several practical advantages. It is more convenient and comfortable to operate in clinic than in a hospital or even an ASC. It is also more cost-effective and more controlled because the supplies, the staff and the protocols are all determined by the surgeon. These features also tend to make the operation safer, particularly when combined with novel technologies designed to facilitate OBS procedures (the SurgiCube, for example, Figure 1).
OBS DMEK has therefore positively transformed our practice, but it has also required us to adopt new routines, including:
1) Topical anesthesia: At the Netherlands Institute for Innovative Ocular Surgery (NIIOS) in Holland, OBS DMEK has always been (and is still) performed using retrobulbar anesthesia. But in Birmingham, Alabama, we have switched to topical tetracaine (with no routine oral or IV anxiolytic). This has been well tolerated, although considering that DMEK is less invasive than routine cataract surgery, perhaps we should have expected this all along.
2) Descemetorhexis under air: Stripping Descemet’s membrane under air maximizes contrast and visibility. Maintaining an air fill of the anterior chamber is typically facilitated using an “air pump,” ie, an anterior chamber (AC) maintainer connected to a source of air infusion (most commonly, a vitrectomy machine). In OBS settings, however, such a machine is not likely to be available. Instead, the AC maintainer may be connected to a 60 cc syringe that is operated by a scrub tech/assistant, applying steady pressure to the plunger to maintain a gentle air flow.
3) Peripheral iridotomy creation: In a hospital setting, our preferred technique for peripheral iridotomy creation is via vitrectomy handpiece. But, again, with the unavailability of such a machine in an OBS setting, we have switched to using a YAG laser on the day of surgery, just before the operation. Fortunately, rates of pupillary block remain low with either technique.
4) No supine posturing: By far, this has been the biggest change to our practice. Conventionally, patients who undergo DMEK maintain supine posturing for 60 to 90 minutes postoperatively and are then discharged with instructions to remain supine for an additional 48 hours. Since switching to OBS DMEK, we have changed our protocol: Now, patients sit up immediately after surgery and proceed home without any positioning instructions. We are in the process of formally collecting our results of “no-supine DMEK” for academic publication, but so far, there does not appear to be any impact on detachment or re-bubbling rates.
OBS DMEK is not a new concept; it has been the “NIIOS standard” for close to 15 years with continued success. And here again, it looks like the world may be ready to follow the lead of Gerrit Melles into the future.
https://parkercornea.com/wp-content/uploads/2021/12/Surgicube.jpeg6301200Parker Corneahttps://parkercornea.com/wp-content/uploads/2021/12/Logo-01.pngParker Cornea2021-04-16 18:19:002022-01-17 16:02:36Success reported with office-based DMEK