EyeWorld Weekly Update, March 10, 2017

2017-03-10

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March 10, 2017
Volume 22 , Number 10

Updated diabetic retinopathy position statement issued by American Diabetes Association

Updated guidelines on the prevention, assessment, and treatment of diabetic retinopathy for clinicians and people with diabetes were published last month by the American Diabetes Association (ADA). The recommendations include new information on the assessment and treatment of diabetic retinopathy and improvements in managing diabetes that have become more common since the previous diabetic retinopathy statement from the ADA in 2002. "New diagnostic developments include the widespread adoption of optical coherence tomography, as well as intravitreal pathology and wide-field fundus photography," according to an ADA press release. "Newer treatment modalities, including intravitreous injection of anti-vascular endothelial growth factor agents, are also outlined in the statement." The recommendations cite studies that show the positive effects of tight glycemic control, the importance of screening at set intervals, and educating pregnant women with preexisting diabetes about the risk of developing diabetic retinopathy. The updated guidelines are published Diabetes Care.

U.S Preventive Services Task Force: Vision screening needed at least once for preschool children

Children ages 3 to 5 should have at least one vision screening to check for abnormalities such as refractive errors, strabismus, and amblyopia, according to new draft recommendations from the U.S. Preventive Services Task Force. The task force wrote that there is not enough evidence to recommend vision screening for children under the age of 12. There is adequate evidence that the treatment of amblyopia or its risk factors can lead to improved visual acuity in children ages 3 to 5, the task force reported. One potential downside of assessment is a high false-positive rate, according to the task force. The draft recommendations are on the U.S. Preventive Services Task Force website and are an update from a 2011 statement. The grades given by the task force for recommended vision screening (a grade of B in children 3 to 5 and an I [insufficient] for children under age 3) remain the same compared with the 2011 statement. There is a 1-month comment period for the recommendations.

Vision may have led early ancestors to walk on land

The power of vision may have led early, ancient, aquatic ancestors to move from water to land, according to research from neuroscientist and engineer Malcolm A. MacIver, PhD, Northwestern University, Evanston, Illinois, and evolutionary biologist and paleontologist Lars Schmitz, PhD, Claremont McKenna, Scripps and Pitzer colleges, Claremont, California. They argue that crocodile-like animals saw easy meals on land, leading to the evolution of limbs that helped them reach those meals. Their study of fossil records found that eyes nearly tripled in size before, not after, the water-to-land transition. "The expanded visual range of seeing through air may have eventually led to large brains in early terrestrial vertebrates and the ability to plan and not merely react, as fish do," according to a Northwestern University press release. The research is published in the Proceedings of the National Academy of Sciences.

RESEARCH BRIEFS

  • There were no alterations in corneal structure tissue properties after trabeculectomy, according to a study from Karin R. Pillunat, MD, and fellow researchers. The accuracy of IOP measurements does not change after surgery, they concluded. Dr. Pillunat and colleagues studied 35 eyes of 35 consecutive patients who had first-time trabeculectomy with mitomycin C in their prospective interventional case series. There was a strong correlation between corneal hysteresis and corneal resistance factor before and after surgery; changes that did occur were not statistically significant. The IOP did decrease significantly; researchers also found that Goldmann-correlated IOP measurements are underestimated in glaucoma patients pre- and postoperatively. The study is published in the Journal of Glaucoma.
  • In eyes with keratoconus, both the posterior axis alignment of corneal astigmatism and alignment of the anterior surface are in line in the majority of cases, researchers concluded. Alignment of the posterior astigmatism axis could perhaps be used in algorithms to support diagnosis and staging of keratoconus, according to Mehdi Shajari, MD, and fellow researchers. Their retrospective cohort study evaluated and compared power and axis orientation of anterior and posterior astigmatism in eyes with keratoconus (861 eyes) against healthy eyes (256 eyes). Magnitude and axis orientation of anterior and posterior corneal astigmatism, corneal thickness, and conus location were measured using a Scheimpflug device. Researchers found the magnitude of corneal astigmatism was 3.47 ± 2.10 D on the anterior surface and 0.69 ± 0.40 D on the posterior surface in eyes across all keratoconus stages. They also observed a significant increase in anterior and posterior corneal astigmatism with disease progression as well as a significant correlation between anterior and posterior corneal astigmatism (r = 0.77, P < 0.01). As keratoconus progresses, anterior and posterior corneal astigmatism alignment becomes increasingly vertical, they wrote. The study is published in Cornea.
  • Eyes with pseudoexfoliation and/or intraoperative signs of zonular weakness have higher complication rates after phacoemulsification, according to Bradford J. Shingleton, MD, and coauthors. Eyes with a nonsutured capsular tension ring still had IOL and capsular complications postoperatively. The retrospective case review included 295 eyes; 143 eyes had pseudoexfoliation with preoperative (Group 1) and intraoperative (Group 2) signs of zonular weakness. The 76 eyes in Group 3 had pseudoexfoliation, and the 76 eyes in Group 4 had neither pseudoexfoliation nor zonular weakness. All eyes had phacoemulsification and IOL implantation done by a single surgeon. Outcome measures included pseudophakodonesis postoperatively, anterior capsule contraction, and IOL decentration/dislocation. Groups 1 and 2 had a higher incidence of complications than Groups 3 and 4 (P < 0.01). All four groups had similar vision, IOP, and glaucoma medication requirements. Groups 1 and 2 had a significantly higher proportion of complications after surgery compared with Group 3 (P < 0.01). There was no significant difference in risk development between Groups 1 and 2 (P = 0.64). The research is published in Acta Ophthalmologica.
  • Accelerated CXL appears to be safe and effective to halt the progression of corneal ectasia, according to a review article from Carla S. Medeiros, MD, and colleagues. Corneal crosslinking has been used increasingly over the past 10 years to halt the progression of ectatic diseases, and there are several new devices that offer high ultraviolet-A irradiation intensity with different time settings. The authors discussed current protocols for accelerated CXL compared with the established conventional method. They found that corneal shape responses varied, as did the demarcation line at different irradiance settings; there was a more superficial demarcation line for shorter exposure times. The review is published in the Journal of Cataract & Refractive Surgery.

PRODUCT BRIEFS

  • The Aladdin Biometer with Corneal Topographer HW3.0 (Topcon Medical Systems, Oakland, New Jersey) has received FDA clearance for distribution in the U.S., according to a press release.

This issue of EyeWorld Weekly Update was edited by Amy Goldenberg and Vanessa Caceres.

EyeWorld Weekly Update (ISSN 1089-0319), a digital publication of the American Society of Cataract and Refractive Surgery and the American Society of Ophthalmic Administrators, is published every Friday, distributed by email, and posted live on Friday.

Medical Editors: Eric Donnenfeld, MD, chief medical editor; Rosa Braga-Mele, MD, cataract editor; Clara Chan, MD, cornea editor; Reay Brown, MD, glaucoma editor; and Vance Thompson, MD, refractive editor.

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