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Preserving MMC’s Reliability
Journal of Glaucoma
Published online May 14, 2015
Kinast et al. compared the effects of common preparation and storage conditions on the stability of mitomycin C (MMC) solutions. They found that the different MMC solutions showed similar stability as soon as they reached room temperature. However, further storage at room temperature led to mild degradation of some of the solutions.
For this study, 5 MMC solutions were freshly prepared according to manufacturers’ standards. Two preparations were stored under refrigeration for 1 or 2 weeks; the third was frozen for 23 days, and the fourth was frozen for 32 days after compounding and then shipped on ice. The fifth preparation was generated using dry powder. The samples were then analyzed after they were warmed to room temperature. This was done at 4 time points: at the moment when they reached room temperature and after 1, 4, and 24 hours.
The researchers found similar high levels of stability when the solutions were analyzed immediately upon reaching room temperature. However, by the 24-hour point, 2 preparations—the solution that had been refrigerated for 2 weeks and the one shipped on ice—showed some degradation. All told, losses of up to 7% of MMC stability were noted.
Although this level of degradation is unlikely to significantly limit fibroblast inhibition, it could possibly affect the consistency of trabeculectomy results, the researchers said.
Gene Therapy for Leber Congenital Amaurosis
New England Journal of Medicine
2015;372(20):1887-1897
Bainbridge et al. set out to evaluate the safety and efficacy of gene therapy in a small group of patients with Leber congenital amaurosis (LCA). Although they found a modest level of improvement, it peaked at 6 to 12 months after treatment and then declined thereafter.
This phase 1/2 open-label trial involved 12 participants, aged 6 to 23 years at enrollment, and lasted 3 years. The gene therapy used—a recombinant adeno-associated virus 2/2 (rAAV2/2) vector that carried the RPE65 complementary DNA—was administered at 2 dose levels.
Improved retinal sensitivity was apparent in 5 of the 8 patients who received the higher dose, and in 1 of the 4 who received the lower dose. This was evident within 1 to 2 months after vector administration, and it continued to progress for 6 to 12 months. Although the improved sensitivity subsequently declined, it was still evident in 2 participants at the 3-year mark. Overall, the level of improvement varied widely among participants, and no improvement was of a magnitude that could be detected by electroretinography (ERG). In addition, no clear correlation emerged between participant age and degree of response.
A parallel study was also conducted in dogs, in which the researchers investigated the relationships among vector dose, visual function, and ERG findings. In this study, substantial improvements in retinal function could be measured by ERG and were highly dose dependent.
Intraoperative Aberrometry and Toric IOLs
Journal of Refractive Surgery
2015;31(4):237-242
Does intraoperative aberrometry improve placement of toric intraocular lenses (IOLs)? Hatch et al. investigated this question and found that it does.
In this nonrandomized retrospective study, 64 eyes underwent cataract surgery with toric IOL implantation. In all eyes, IOL power and alignment were determined by means of automated keratometry, standard optical biometry, and an online calculator; this process was further refined with intraoperative aberrometry in 37 of the 64 eyes.
The mean postoperative residual refractive astigmatism (RRA) was 0.46 ± 0.42 D and 0.68 ± 0.34 D in the eyes evaluated with and without aberrometry, respectively. Further analysis indicated that intraoperative aberrometry yielded better results not only in postoperative RRA but also in manifest cylinder reduction and in manifest cylinder percentage change.
The authors acknowledged that intraoperative aberrometry has drawbacks, including cost, additional time in the operating room, and a learning curve for the surgeon.
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Roundup of Other Journals is written by Jean Shaw and edited by Deepak P. Edward, MD.
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