• Wear of scleral lenses over longer periods of time may exacerbate corneal swelling, reports a study in the March 2016 issue of Optometry and Vision Science.1
Researchers used Scheimpflug imaging to examine the corneas of healthy patients before and immediately after eight hours of high Dk miniscleral lens wear, finding that a low level of corneal edema occurred by the eight-hour mark. Though the level of swelling was less than typically observed following overnight eyelid closure, these findings do contradict earlier research that suggests hypoxia-related changes to the cornea stabilize at three hours of wear time, the researchers note.2,3 They suggest further research be conducted.
1. Vincent, S, Alonso-Caneiro D, Collins M, et al. Hypoxic corneal changes following eight hours of scleral contact lens wear. Optometry and Vision Science. 2016 Mar. 93(3):293-9.
2. Sarver MD, Polse KA, Baggett DA. Intersubject difference in corneal edema response to hypoxia. Am J Optom Physiol Opt. 1983 Feb:60(2):128-31.
3. Holden BA, Sweeney DF, Sanderson G. The minimum precorneal oxygen tension to avoid corneal edema. Invest Ophthalmol Vis Sci. 1984 Apr:25(4):476-80.
• An unstable tear film may indicate candidates who will fail to take to gas permeable lens wear, reports a study in the March 2016 issue of Eye & Contact Lens.1 Twenty-two participants were given GP lenses to wear daily for one month, with follow-up visits scheduled at one, seven, 15 and 28 days. Six patients dropped out due to discomfort; those that remained but reported dissatisfaction exhibited lower comfort scores and wear time due to dryness.
1. Carracedo G, Martin-Gil A, Peixoto-de-Matos S, et al. Symptoms and signs in rigid gas permeable lens wearers during adaptation period. Eye & Contact Lens. 2015 Mar;42(2):108-14.
• Including organoselenium in the polymer of contact lens cases could inhibit biofilm formation, suggests a study published online in Eye & Contact Lens.1 Researchers tested the effects of the material on the growth of Pseudomonas aeruginosa, Staphylococcus aureus, Stenotrophyomonas maltophilia and Serratia marcescens by incubating the bacteria overnight in the presence of both a polypropylene polymer containing organoselenium and the same polymer without organoselenium. Results indicated the presence of the organoselenium inhibited growth of all bacteria by nearly 100%.
1. Tran P, Huynh E, Pham P, et al. Organoselenium polymer inhibits biofilm formation in polypropylene contact lens case material. Eye & Contact Lens. 2016 Mar; [Epub ahead of print.]