Peroral caffeine consumption reduced ultraviolet radiation (UVR)-induced apoptosis in human lens epithelial cells (LEC) in vitro, researchers found in a prospective randomized controlled observer-blinded pilot study published in Acta Ophthalmologica.1

While prior research indicated peroral caffeine consumption increased caffeine levels in lens capsule/epithelial cells, and that caffeine eye drops administered to UVR-exposed rats protected against cataract development, this study sought to determine the role of perorally consumed caffeine on cataract prevention.2,3

The researchers analyzed 34 lens capsules with adhering LECs from 17 patients (10 females) with bilateral cataract (13 with bilateral mixed cataract and 4 with bilateral nuclear cataract) who had an approximate mean age of 73 years . Patients who had pseudoexfoliation syndrome of the lens, systolic hypertension of greater than 160 mm Hg at the day of surgery, or who were pregnant were excluded.


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The researchers recruited the subjects 1 week before cataract surgery on the first eye with the sedoanalgesia technique. They asked the subjects about their last caffeine intake and overall caffeine habits. The researchers conducted a standard eye exam at the baseline visit that included slit lamp biomicroscopy with LOCS II grading and retinal exam, visual acuity testing, biometry of both eyes, and blood pressure measurement. The patients were asked to avoid drinking caffeinated beverages until cataract surgery of the second eye, which occurred 2 weeks after the baseline visit. Approximately  165 minutes prior to the surgery of the second eye, the subjects were asked to drink a cup of coffee containing 180 mg caffeine.

In both surgeries, the researchers performed standardized main incision and paracentesis to harvest the anterior lens capsule and adhering LEC. Each lens capsule was immediately exposed to UVR while in a balanced salt solution (BSS), which was then replaced by a culture medium. 

The lens capsules with adhering LECs were then cultured with CO2 for 24 hours in a humified incubator. On the day after surgery, the specimens were fixed in a formaldehyde solution and permeabilized in phosphate-buffered saline. The researchers stained the lens capsules with a commercial TdT-mediated dUTP-biotin nick end labeling (TUNEL) assay kit, took pictures of 3 sections of each lens capsule, and calculated the percentage of apoptotic cells.

They found that 10 kJ/m2 of UVR was the lowest amount that successfully induced TUNEL staining in both the treatment and control groups after the first and second surgeries. LEC after the caffeine intake that immediately preceded the second surgery showed significantly less TUNEL staining than LEC without caffeine intake (95% confidence interval (.95) = 15.3 +/- 10.4%, degrees of freedom: 16, P = .011).

The researchers said that other antioxidant compounds of coffee may have boosted the benefit of the caffeine; but chlorogenic acids are destroyed during the roasting process, and pyrocatechol’s pharmacokinetics and stability during UVR exposure “remain unclear.” Thus, they maintained that caffeine is the most important antioxidant of coffee that prevents UVR-induced cataract.

“Considering pharmacokinetics and the protective effect, we would suggest that caffeine be consumed just before sun exposure similar to sunscreens,” the researchers said.

Reference

1. Kronschläger M, Ruiß M, Dechat T, and Findl O. Single high-dose peroral caffeine intake inhibits ultraviolet radiation-induced apoptosis in human lens epithelial cells in vitro. Acta Ophthalmol. Published online October 30, 2020. doi: 10.1111/aos.14641

2. Kronschläger, M, Forsman E, Yu Z, et. al. Pharmacokinetics for topically applied caffeine in the rat. Exp Eye Res. 2014;122:94-101. doi: 10.1016/j.exer.2014.03.009

3. Kronschläger M, Stimpfl T, Ruiß M, Hirnschall N, Leisser C, and Findl O. Pharmacokinetics of caffeine in the lens capsule/ epithelium after peroral intake: a pilot randomized controlled study. Invest Ophthalmol Vis Sci. 2018;59:1855-1860. doi: 10.1167/iovs.18-23963