Hard-boiled eggs can be used for warm compresses, but the pressing force may distort the corneal shape. This study investigated the effect of warm compress therapy on the corneal shape by using hard-boiled eggs as the heat source.
Twenty-five young adult Chinese were recruited, and 1 eye was randomly selected to undergo the following treatment protocols in a random order: hot hard-boiled egg covered with wet cloth gently touching the eyelid; hot hard-boiled egg covered with wet cloth placed close to, but not touching, the eyelid; and cold egg covered with wet cloth gently touching the eyelid. Each treatment protocol lasted for 5 minutes. Eyelid temperature was measured using an infrared thermometer before and every 1 minute during the treatment. Corneal parameters, including SimK, best-fit sphere (BFS), surface asymmetry index (SAI), and surface regularity index (SRI), were measured by a corneal topographer before and after the treatment.
Treatment 1 gave a 3.5°C skin temperature rise within 3 minutes. The skin temperature rise was around 2.5°C in treatment 2. There was no skin temperature change in treatment 3. Both treatments 1 and 3 affected the SAI and SRI. There was no significant change on other corneal parameters from treatments.
Because it is difficult to standardize the pressing force, it is recommended to place the hard-boiled egg close to, but not touching, the eyelid during warm compress therapy. The temperature rise from this treatment protocol should be large enough to melt the meibomian gland secretions without distorting the corneal shape.