Small Incisions, Big Breakthroughs
A Report from the ASRS
■ Groundbreaking new technology and strategies for success with microincision vitrectomy surgery were among the topics featured at the 26th annual meeting of American Society of Retina Specialists in Maui, HI, with experts from around the world presenting the latest data plus their own clinical impressions and guidance on small-incision procedures. Below are selected highlights of the scientific presentations.
• "Preclinical and Clinical Experience with a New Duty Cycle Controlled Vitrectomy Probe." A novel duel-pneumatic vitrectomy probe that can perform 5000 cuts per minute (CPM) was compared with an older, standard model 20-gauge pneumatic probe in a presentation by Kirk Packo, MD, of Rush University Medical Center in Chicago. The new probe, designed by Alcon Laboratories, Inc. (Fort Worth, Texas), was able to achieve a greater than 50% duty cycle at 5000 CPM, allowing for high vitreous flow rate with minimal traction.
The older model probe was unable to match these performance measures. While it was able to achieve a 50% duty cycle, it could only do so at a CPM of 1000, compared to the new probe's 5000. The older probe, when operating at its maximum CPM of 2500, could only achieve a duty cycle of 30%.
The new probe allows the surgeon to control vitreous flow by controlling duty cycle — a new concept in probe design. Early experience in human subjects showed this new style of vitrectomy control to be safe and effective, Dr. Packo said.
|This article is based on the synopses of microincision vitrectomy surgery and equipment presentations published in the 2008 American Society of Retina Specialists 26th annual meeting guide. The information presented was edited by the Retinal Physician editorial staff. The views expressed are those from the meeting guide and do not necessarily reflect the views of Alcon or the particular surgeons highlighted.|
• "Laboratory and Clinical Evaluation of the Alcon CONSTELLATION® Vitreoretinal System." Pioneering retinal surgeon Steve Charles, MD of Memphis, TN offered his impressions of the CONSTELLATION® Vitrectomy System from Alcon Laboratories, Inc. (Fort Worth, Texas) based on five months of clinical experience at the time of presentation. The CONSTELLATION® was found to be safe and effective, with new features that equaled or exceeded specifications and offered a significant performance increase over the ACCURUS® system and others.
The new features include: a plug-and-play RFID and bar code reader, push priming, a tubing management system that clips to a sterile articulated arm, an inclinable and rotatable display with an advanced user interface and embedded directions for faster, error-free setup and use, flow or pressure control for aspiration, servo-controlled intraocular pressure, a dual pneumatic drive axial cutter with 5000 cuts per minute and variable duty cycle, proportional diathermy, power scissors and power forceps with single foot pedal control for bimanual surgery, auto-fill gas syringe, auto-stopcock for fluid-air exchange, proportional and micro reflux, single or dual xenon light source with 2-4 ports and RFID automatic adjustment of intensity, embedded PUREPOINT® 532nm diode-pumped laser, voice verification of tools, parameters and modes, and post-surgical automated documentation.
• "Controlled Bimanual Vitrectomy (CON BI VI) Technique for Extending Treatment in Aphakic Retina Detachments." Small-gauge surgery for retinal reattachment can provide outcomes comparable to or better than conventional 20-gauge techniques, with greater patient comfort and improved postoperative healing. Greece's Athanasios Nikolakopoulos, MD, presented the results of a study comparing 20-gauge and 25-gauge surgery for retinal reattachment, with 154 cases in each group. Success rate was 85% in the 20-gauge group and 89.5% in the 25-gauge group. There were 11 cases of tear enlargement in the 20-gauge group but just a single case in those who underwent 25-gauge surgery. Neither group experienced endophthalmitis.
Dr. Nikolakopoulos commented that the controlled bimanual vitrectomy technique using 25-gauge instruments was less traumatic for patients, with reduced post-operative inflammation and faster rehabilitation time relative to 20-gauge procedures, even in complicated cases.
• "Rate of Recurrent Retinal Detachment Between 20-Gauge and 25-Gauge Pars Plana Vitrectomy for Primary Retinal Detachment Repair." Recurrence of retinal detachment following surgical reattachment occurs less frequently in 25-gauge surgery than in 20-gauge procedures, according to Richard M. Feist, MD, of Birmingham, AL. Dr. Feist presented results of a retrospective chart review of 195 retinal reattachment cases performed with either 20-gauge or 25-gauge pars plana vitrectomy. The recurrence rate after surgery was 33% in the 20-gauge group, a rate noted to be significantly greater than that of the 25-gauge group. Best corrected visual acuity improved from 20/400 to 20/150 in the 20-gauge group and from 20/200 to 20/50 in the 25-gauge group.
• "20-, 23- and 25-Gauge Vitrectomy for Repair of Primary Rhegmatogenous Retinal Detachment — A Comparison." Preoperative proliferative vitreoretinopathy and phakic status, rather than instrumentation gauge, were found to be associated with surgical failure in repair of retinal detachment, according to a study presented by Colin A. McCannel, MD, of the Mayo Clinic in Rochester, MN. In a retrospective review of 119 cases of rhegmatogenous retinal detachment repaired using 20-, 23- or 25-gauge techniques, the primary success rate was 92.8% in 20-gauge cases, 90.9% in 23-gauge cases, and 92.0% in 25-gauge cases. The authors concluded that instrumentation gauge did not affect surgical success rate.
OUTCOMES & COMPLICATIONS
• "Surgical Outcomes of Micro-Incision Vitrectomy Surgery." Small-gauge surgery is safe and effective for a variety of retinal procedures, particularly macular surgery, according to a retrospective study of 5453 cases performed by Italy's Stanislao Rizzo, MD, 59% of which underwent 25-gauge surgery and 41% underwent a 23-gauge procedure. Conditions treated included epiretinal membrane, macular hole, refractory macular edema, retinal detachment, and non-clearing vitreous hemorrhage. Primary outcome measures included best corrected visual acuity (BCVA) at six months, postoperative intraocular pressure (IOP), operating time and postop complications. BCVA improved from 20/100 preoperatively to 20/40 for the entire series, with statistically significant improvement noted in each subgroup.
No intraoperative complications were attributed to 23- or 25-gauge techniques, and no cases required conversion to a 20-gauge procedure. IOP remained stable in 94.5% of cases, with the remaining 5.5% experiencing hypotony during the first postoperative week. Endophthalmitis occurred in just one case. Retinal detachment due to incomplete vitreous shaving was reported to be the main postop complication, and can be overcome by complete vitrectomy, the authors stated.
• "Outcomes of 23-Gauge Pars Plana Vitrectomy for Posterior Segment Disease." In a retrospective case series, presented by Christopher Singh, MD, of 69 eyes undergoing 23-gauge pars plana vitrectomy for a variety of retinal diseases, mean visual acuity improved from 20/400 preoperatively to 20/160 at one month postop and 20/114 at three months. Conditions treated included diabetic macular edema, diabetic traction detachment with vitreous hemorrhage, epiretinal membrane, macular hole, nonclearing vitreous hemorrhage, retained lens fragments, rhegmatogenous retinal detachment and vitreomacular traction. Intraocular pressure greater than 22 mmHg developed in 58% of cases and over 30 mmHg in 13% of cases. None experienced hypotony. Glaucoma suspects were more likely to develop elevated IOP at one week or later postoperatively and may require aggressive treatment.
• "Endophthalmitis After 25-gauge Pars Plana Vitrectomy: A 20- and 25-gauge Comparison." Although recent retrospective analyses have suggested a higher rate of endophthalmitis in patients who have undergone 25-gauge pars plana vitrectomy (PPV) compared to 20-gauge cases, a study presented by Allen Y. Hu, MD, of Los Angeles found that the incidence was low in both groups, with no significant difference between the sutureless 25-gauge and sutured 20-gauge cases.
In this retrospective single-center study of 3486 PPV cases — 41% of which underwent sutureless 25-gauge PPV and 59% underwent 20-gauge sutured PPV — only one case of endophthalmitis developed in the 25-gauge group, for a rate of 0.69%; no cases developed in the 20-gauge patient population.
• "25-gauge Macular Hole and Pucker Surgery: Results and Complications." 25-gauge pars plana vitrectomy (PPV) for macular surgery produces excellent visual outcomes with minimal complications, according to a study presented by John Mason, MD, of the University of Alabama at Birmingham. In this retrospective series of 290 eyes that underwent 25-gauge PPV for macular hole or macular pucker, outcome measures were visual acuity, intraocular pressure, complications and cataract progression.
At mean follow-up of 12 months, visual acuity improved from 20/80 preoperatively to 20/40 for macular hole patients and 20/30 for macular pucker cases. Significant cataract progression was seen in 22% of macular hole cases and 16% of macular pucker cases at six months. Two retinal detachments developed in each series, for an incidence of 0.017% in macular hole and 0.012% in macular pucker. Transient hypotony at one week occurred in 0.029% of macular pucker cases but none with macular hole. RP