Sunlight after cataract surgery should be limited depending on type of implant placed: most protect against UV but some do not. Sun can damage macular tissues so check with your eyeMD to discuss how strict sunglasses/hat use should be. In general most eyeMDs recommend protection from sun for majority of patients most of hours of day: plus or minus a couple of hours of non-direct sunlight to eyes.
The natural VISIBLE daylight spectrum of light helps regulate circadian hormone regulation
UV light on the skin helps synthesize “vitamin” D (it is a misnomer – it’s really a pre-hormone). Seasonal Affective Disorder (SAD), a type of depression, can occur due to lack of Vit D.
It has been demonstrated that daylight lamps really help with SAD, but the below article shows that Vit D supplementation is NOT as useful.
UV light on the skin helps produce Vitamin D, but it can be harmful to the eyes, thus the need to protect the eyes.
There is not great published research on this issue that I could find to date, but many consider the sub 400 nm wavelength UV spectrum to be of importance in Vit D production and thus skin exposure to the sun should occur roughly 2 hrs either side of midday: “sunrise” is around 11am, and “sunset” is around 3pm in the summer (daylight saving assumed, so that midday is 1pm). In short, this means that there’s little point in sunbathing outside those hours, since you won’t generate any Vit D. Studies have shown also that patients living in northern cities north of Washington DC area do not produce enough natural Vitamin D from sun exposure in winter months.
Most eyeMDs still recommend sunglasses the majority of the time to prevent damaging UV rays on the macula and lens.
Basic research continues to show (see below) the potentially damaging effects of UV exposure on cell death and apoptosis (programmed cell death).
Impact Factor of this journal: 1.663
In Vitro Model for Predicting the Protective Effect of Ultraviolet-Blocking Contact Lens in Human Corneal Epithelial Cells.
Abstract Purpose: To develop an in vitro method to determine the protective effect of UV-blocking contact lenses (CLs) in human corneal epithelial (HCE) cells exposed to UV-B radiation. Materials and Methods: SV-40-transformed HCE cells were covered with non-UV-blocking CL, UV-blocking CL or not covered, and exposed to UV-B radiation. As control, HCE cells were covered with both types of CLs or not covered, but not exposed to UV-B radiation. Cell viability at 24, 48 and 72 h, after UV-B exposure and removing CLs, was determined by alamarBlue® assay. Percentage of live, dead and apoptotic cells was also assessed by flow cytometry after 24 h of UV-B exposure. Intracellular reactive oxygen species (ROS) production after 1 h of exposure was assessed using the dye H2DCF-DA. Results: Cell viability significantly decreased, apoptotic cells and intracellular ROS production significantly increased when UVB-exposed cells were covered with non-UV-blocking CL or not covered compared to non-irradiated cells. When cells were covered with UV-blocking CL, cell viability significantly increased and apoptotic cells and intracellular ROS production did not increase compared to exposed cells. Conclusions: UV-B radiation induces cell death by apoptosis, increases ROS production and decreases viable cells. UV-blocking CL is able to avoid these effects increasing cell viability and protecting HCE cells from apoptosis and ROS production induced by UV-B radiation. This in vitro model is an alternative to in vivo methods to determine the protective effect of UV-blocking ophthalmic biomaterials because it is a quicker, cheaper and reliable model that avoids the use of animals.
Sunlight, Vitamin D, and Depression
Vitamin D metabolism is dependent on sunlight, and lack of sunlight is linked to depression, so it is logical to assume that a lack of vitamin D might be a cause of depression. But is it? A team of investigators from Tromsø in Norway have performed a study to compare depressive symptoms in participants with low and high serum vitamin D levels and to examine whether supplementation with vitamin D would improve symptoms in those with low serum levels.
A sample of 230 participants with low vitamin D levels was randomly assigned to receive either placebo or 40,000 IU vitamin D per week for 6 months, and 114 individuals with high serum levels were used as nested controls. Depressive symptoms were evaluated with several well-validated depression rating scales.
The investigators found that the participants with low levels of vitamin D were more depressed than participants with high levels, but in the intervention study, no significant effect of high-dose vitamin D was found on depressive symptom scores when compared with placebo. From a clinician’s perspective, our advice to our depressed patients must remain the same: Stick to the sunlight rather than taking extra vitamin D.