Eyeworld

EW CATARACT 86 April 2017 Presentation spotlight by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer Blue-blocking IOLs disturb the natural sleep cycle, new study shows T heories that wavelengths in the blue light range could be related to the pathogen- esis of age-related macular degeneration (AMD) have prompted interest in yellow-tinted IOLs for patients requiring cata- ract surgery, which filter out short wavelength light and protect the retina from further damage. The literature, however, does not agree on the advantages of blue-blocking IOLs. It also does not agree on the potentially disturbing effects that blue blockers can have on a person's sleep/wake cycle. New evidence suggests that yellow chromophore IOLs are detrimental to the circadian sleep cycle and hence diminish the quality of sleep in patients under- going bilateral cataract surgery, as reported at the XXXIV Congress of the European Society of Cataract and Refractive Surgeons (ESCRS) in Copenhagen, Denmark, this past fall. Changes in the circadian cycle in patients undergoing cataract sur- gery through the direct comparison of two different IOLs, a blue light blocker and a conventional IOL, were the subject of a new prospec- tive, comparative, non-interven- tional, longitudinal study, presented by Catalina Rojas-Rosario, MD, Hospital de la Luz, Mexico City, Mexico. It was conducted in patients undergoing bilateral cataract surgery with IOL implantation, from May to September 20, 2015. Group A had 24 patients (60%) whose mean age was 69.5 years (range: 44–91 years) and included individuals receiving an IOL with yellow chromophores, and Group B had 16 patients (40%) whose mean age was 68.1 years (range: 52–84 years) (P = .3646) and included those receiving an IOL without blue blocking yellow chro- mophores. In Group A, 13 patients were female (54%) and 11 were male (46%). In Group B, 11 patients were female (68%) and five were male (32%). In both groups, the Pittsburg Sleep Quality Index (PSQI) 7 self-re- port questionnaire was completed by the study participants both before and after cataract surgery. The PSQI questionnaire measures several different aspects of sleep such as subjective sleep quality, sleep laten- cy, sleep duration, sleep disturbanc- es, and daytime dysfunction, among other components. Each item is weighted on a scale from 0–3 result- ing in a composite score from 0–21, with lower scores denoting healthier quality sleep. It scores sleep for the duration of 1 month and takes be- tween 5–10 minutes to complete. The study also measured day- time melatonin levels from saliva using MicroELISA as a more objec- tive measure of circadian rhythms. Melatonin forms part of the system that regulates the sleep/wake cycle by causing drowsiness and lowering the body's temperature. Its produc- tion in the pineal gland is inhibited by light and permitted by darkness. Normally, serum melatonin levels peak in the middle of the night. A strong correlation exists between se- rum melatonin concentrations and salivary melatonin, which the study used to assess physiological daytime levels of the hormone. All of the results were compared between the two groups. "Reduced melatonin means re- duced sleep. Intraocular lenses with yellow chromophores that block blue light may make patients suscep- tible to sleep disturbances, daytime sleepiness, or depression," Dr. Rojas– Rosario said. The study outcomes showed a pre-cataract surgical mean PSQI composite score of nearly 7 in Group A that received blue-block- ing IOLs and 6 in Group B with conventional IOLs (P = .4613). The mean postsurgical PSQI score was nearly 8 in Group A and 6 in Group B (P = .0416). While the PSQI score remained roughly the same in Group B, it was higher in Group A, indicating worse sleep quality in this group on whole. Postoperative melatonin measurements showed mean melatonin levels of 3 pg/ml (P = .0022) in Group A and melatonin levels of under 2 pg/ml (P = .0022) in Group B. "Wavelengths in the blue light range around 475 nm are responsi- ble for 55% of circadian phototrans- duxtion, which increases cognition and alertness. Blue light entering the eye activates the melanopsin signaling system expressed in retinal ganglion cells, which relay the impulse to the pineal gland, where melatonin is produced. At present, there is no evidence that shows a Shedding light on the body's biological clock: Blue light capsule, that release of pressure itself causes some capsular relaxation and inherent movement of the tissue. Additionally, in a longer capsulot- omy, the milky white fluid leaking out of the capsule could obstruct the laser path. There is significant variation in capsulotomy speed among the femtosecond lasers on the market, with some taking as long as 4 to 6 seconds to create the capsulotomy. I believe it is important to know your laser's capsulotomy speed and the rate of free caps versus capsulotomy irregularities before attempting LACS in an eye with intumescent cataract. Settings It is also important to be aware of how the laser settings may affect the capsulotomy speed. Tighter spot overlap can improve the chance of a complete capsulotomy but may lengthen the procedure. Because femtosecond laser cavitation bubbles occur in a column, we can consider making the vertical space between spots a little further apart to increase speed. I have been tracking my cap- sulotomy times. With the default Catalys laser settings of 10 µm verti- cal x 5 µm horizontal spot spacing, a 5.0-mm capsulotomy at 600-µm depth (300 µm above and below the capsule) takes about 1.6 seconds. By increasing the vertical spot spacing from 10 µm to 15 µm, I am able to routinely create a 5.0-mm capsu- lotomy in 1.1 seconds. This is very encouraging, because it is faster than the fastest Argentinian flag sign tear- out I observed. However, surgeons should famil- iarize themselves with the speed and dynamics of their femtosecond laser systems. EW References 1. Schultz T, Dick HB. Laser-assisted mini-capsulotomy: A new technique for intumescent white cataracts. J Refract Surg. 2014;30:742–5. 2. Conrad-Hengerer I, et al. Femtosecond laser-assisted cataract surgery in intumes- cent white cataracts. J Cataract Refract Surg. 2014;40:44–50. Editors' note: Dr. Page is in practice at Oakland Ophthalmic Surgery in Birmingham, Michigan. Contact information Page: tpagemd@yahoo.com Femtosecond continued from page 84 continued on page 89

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