Heat Transfer Analysis of the Human Eye During Exposure to Sauna Therapy

Abstract

Among the reported health benefits of a sauna session are weight loss, detoxification of the body, and improved blood circulation. Side effects of sauna therapy, both beneficial and detrimental, also exist. It is well known that the human eye is one of the most sensitive parts of the entire human body when exposed to high ambient temperature and humidity levels such as in sauna therapy. This sauna heat interacts with the human eye and may lead to a variety of ocular effects due to radiation emitted by the heater and high ambient temperature. However, the resulting thermophysiologic response of the human eye to various exposure conditions during sauna therapy is not well understood. Therefore, it is of interest to investigate the potential ocular effects that may occur during sauna exposure. This study presents a numerical analysis of heat transfer in a heterogeneous model of a human eye exposed to sauna. The heat transfer model is developed based on porous media theories. In the heterogeneous human eye model, the effects of room air temperature and heater temperature on the intraocular temperature increase are systematically investigated. The study intends to focus attention on the different heat transfer characteristics between conventional sauna (mainly convection) and infrared sauna (mainly radiation). The results show that at the same room air temperature, the circulatory patterns within the anterior chamber of the eye in regard to infrared sauna are more rapid than those for the conventional sauna. Moreover, eye temperature is also higher in the infrared sauna than in the conventional sauna. The maximum temperatures of the eye exposed to conventional and infrared saunas at room air temperature of 80 C are 48.25 C and 52.90 C, respectively. From the values obtained, a guideline can be recommended to indicate the limitations in regard to temperature increase in the human eye due to sauna therapy.

Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review

“…In the medical literature at large, there are reports of severe adverse effects from saunas that include dry sauna-induced burns [ 93 ] and myocardial ischemia (especially in patients with unstable coronary artery disease) [ 94 ], along with less frequent reports of syncope/falls [ 1 ], hypersensitivity pneumonitis (“sauna lung”) [ 95 ], nonexertional heatstroke [ 96 ], rhabdomyolysis [ 93 ], ocular irritations [ 97 ], “sauna stroke syndrome” [ 98 ], and death [ 99 ]. The risk of death from saunas was examined in retrospective population studies of frequent sauna users in Sweden and Finland, with the annual death rate from saunas being reported as 0.06 and 2 per 100,000 inhabitants, respectively, with half or more of all these deaths involving the use of alcohol and a common risk factor of sauna bathing alone [ 99 , 100 ].…”

Thermal Effects on Fluid Mixing in the Eye

“…The heating element temperature was kept constant throughout the experiment by applying a constant voltage from the power supply. The selected temperature range is safe for applications on human eyes, 18 as some commercial eye heating masks already have temperature settings that exceed this range [such as Aroma Season moist heated eye mask for stye blepharitis treatment with flaxseed, which has a heating range from 40 (104°F) to 60°C (140°F)]. Before running the actual experiments, we used the same setup to monitor temperature variation in 1 h with the aid of an FLIR SC6700 infrared camera (equipped with FLIR Exam IR software) and an Omega Engineering HH806AU thermometer (equipped with surface thermocouple with self-adhesive backing, Type k).…”

Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources

“…In a series of studies, Wessapan and Rattanadecho [19][20][21][22] investigated the elevation in the ocular temperature when exposed to electromagnetic (EM) waves using a two-dimensional model. A similar study was carried out to look at the ocular temperature distribution during sauna therapy [23] . Although the models took into account the effects of AH flow, they were developed in two-dimensions, which do not fully represent the anatomical structure of the human eye.…”