| ◄▬ | 2016 Crama en Klevering | ▬► |
Crama en Klevering, The Removal of Hydrogel Explants, An Analysis of 467 Consecutive Cases,
the American Academy of Ophthalmology,
http://dx.doi.org/10.1016/j.ophtha.2015.08.018
abstract
Purpose: To describe the complications associated with hydrogel explants and to describe the indications,surgical technique, and risks involved in the removal of a hydrogel explant.
Design: Single-center, retrospective interventional case series.
Participants: Patients who underwent surgical removal of a symptomatic, swollen hydrogel explant.
Methods: We reviewed the medical records of 457 consecutive patients (467 eyes in total) who underwent surgical removal of a symptomatic, swollen episcleral MIRAgel (MIRA Inc., Waltham, MA) explant at the Radboud University Medical Center from 1998 to 2011. We reviewed the initial symptoms, clinical findings, surgical aspects,
and intraoperative and postoperative complications.
Main Outcome Measures: Presenting symptoms, retinal redetachment rate, and intraoperative scleral perforation.
Results: The median interval between initial placement of the hydrogel explant and removal of the explant was 159 months. More than 34% of the episcleral hydrogel explants developed symptomatic swelling and required surgical removal. Intraoperative scleral perforation or retinal redetachment related to the removal of the
explant occurred in 11% of patients.
Conclusions: The percentage of explants that ultimately develop symptomatic swelling is considerably higher than reported previously. A swollen hydrogel explant can be removed many years after the primary detachment surgery, and 11% of cases develop intraoperative scleral perforation or retinal redetachment.
In hun artikel van 2016 vermelden Crama en Klevering de aanvankelijke voordelen van de in 1985 ontwikkelde Miragel plombe. Na een aantal jaren werd echter een ernstig materiaalgebrek ('serious flaw') ontdekt. De oorzaak bleek te zijn de hydrolytische afbraak van het MIRAgel materiaal (‘hydrolytic degradation of the MIRAgel material’).
In 1985, an episcleral hydrogel explant (MIRAgel, MIRA Inc., Waltham, MA) was introduced as an alternative to silicone explants for the treatment of rhegmatogenous retinal detachment.1 The original explant (in its original shape and dimensions) is shown in Figure 1. This episcleral buckle originally seemed promising for 2 main reasons. First, the material’s soft, pliable characteristics have the potential to minimize scleral erosion. Second, the explant can absorb and then release antibiotics, thereby helping to prevent postoperative infection. Despite these potential advantages, after several years a serious flaw was discovered in the material. Specifically, hydrolytic degradation of the MIRAgel material causes progressive swelling of the explant, which can lead to strabismus, ptosis, scleral erosion, conjunctivitis, and infection around the buckle; in addition, significant cosmetic problems also can arise.2-8
Nt.2 Marin JF, Tolentino FI, Refojo MF, Schepens CL. Long-term complications of the MAI hydrogel intrascleral buckling implant. Arch Ophthalmol 1992;110:86–8.
Hoewel MIRA Inc. midden jaren ’90 MIRAgel van de markt haalde, was volgens de auteurs MIRAgel buiten de Verenigde Staten nog commercieel verkrijgbaar tot 2000
Of note, in 1995 the production facilities of the company that made MIRAgel (MIRA Ine) were closed by the Food and Drug Administration because of repeated violations of Good Manufacturing Practica regulations. However, this action was not specifically related to MAI or MIRAgel.21 Moreover, a formal recall was never issued for MAI or MIRAgel products (personal communication with the Food and Drug Administration, December 10-13, 2010). Although the company closed in the United States, MIRAgel continued to be distributed outside of the United States after 1995, and some surgeons used this material until the year 2000.16
Nt.21 Farley D. Device firm closes pending compliance with FDA regulations. FDA Consumer 1995;29:32.
Nt.16 Roldán-Pallarés M, Hernández-Montero J, Llanes F, et al. MIRAgel: hydrolytic degradation and long-term observations. Arch Ophthalmol 2007;125:511–4
Verder schrijven de auteurs o.m.:
(...) When symptomatic swelling occurs, surgical removal of the buckle is usually the only feasible option available.
However, removal of the buckle also carries risks, including vision-threatening complications such as retinal redetachment and intraoperative scleral rupture.
Only patients who had a MIRAgel explant that caused severe symptoms were considered for removal.
Methods
We reviewed the medical records of all consecutive patients who underwent surgical removal of a symptomatic, swollen episcleral MIRAgel explant at the Radboud University Medical Center in Nijmegen, The Netherlands, from January 1, 1998, to December 31, 2011.
(...)
Before the removal surgery, each patient underwent a complete ophthalmological evaluation, including initial best-corrected visual acuity (Snellen), slit-lamp biomicroscopy, indirect ophthalmoscopy, and Goldmann applanation tonometry.
(...)
The presenting symptoms were classified as cosmetic problems, pain/discomfort, eye motility disorders or diplopia, extrusion or exposure of the buckle, active ocular infection, and other symptoms.
Results
During the study period, we removed MIRAgel explants from 467 eyes in 457 patients. These MIRAgel explants were originally implanted in patients from 1986 to 1997; 461 were implanted in patients at the Radboud University Medical Center, and 6 were implanted in patients elsewhere.
(...)
The patients presented with a variety of symptoms that necessitated removal of the explant; however, the majority of patients (70%) presented with pain or discomfort. The indications for surgical removal are summarized in Table 1.(p.35 lk)
(...)
Next, we evaluated the risk that receiving a MIRAgel explant can lead to serious complications that ultimately necessitate removal of the explant by determining the total number of MIRAgel explants that were implanted in patients at Radboud University Medical Center from 1986 to 1997. Although this number could not be determined directly from the surgical data, we determined that a total of 1354 MIRAgel explants were delivered to Radboud University Medical Center from 1986 to 1997. By comparing this number with the number of explants we removed from our own patients (461), it can be concluded that 34% of MIRAgel explants (461/1354) eventually need to be removed because of symptomatic swelling, with an average postimplantation interval of approximately 13 years (159 months; range, 54-284 months).
(...)
The symptoms that led to the surgical removal of MIRAgel explants in our series are consistent with previous reports. The most commonly reported symptoms were pain or discomfort (in 70% of cases), cosmetic problems (49%), eye motility disorders (39%), diplopia (29%), periocular infection (27%), aal perforation during removal: multiple (i.e, >2) previous retinal procedures (OR, 3.4) and the presence of an active periocular infection (OR, 2.8). Despite the increased risk of scleral perforation, in cases with an active periocular infection, prompt surgical removal is likely the best decision, because postponing surgical removal does not decrease the risk of intraoperative scleral perforation, and bacteria are extremely difficult to eradicate from an inflamed environment such as the MIRAgel material.
(...)
Next, we evaluated the risk that receiving a MIRAgel explant can lead to serious complications that ultimately necessitate removal of the explant by determining the total number of MIRAgel explants that were implanted in patients at Radboud University Medical Center from 1986 to 1997. Although this number could not be determined directly from the surgical data, we determined that a total of 1354 MIRAgel explants were delivered to Radboud University Medical Center from 1986 to 1997. By comparing this number with the number of explants we removed from our own patients (461), it can be concluded that 34% of MIRAgel explants (461/1354) eventually need to be removed because of symptomatic swelling, with an average postimplantation interval of approximately 13 years (159 months; range, 54-284 months).
(...)
In our study, 34% of eyes implanted with MIRAgel developed symptomatic swelling that was serious enough to warrant removal of the explant after a median postimplantation period of 159 months.
| ◄▬ | 2016 Crama en Klevering | ▬► |