Sun gazing has been been helpful for a lot of people, but Pitta types (fair, freckled, reddish skin, reddish/blond hair, do best having only indirect sunlight exposure. Their skin reddens quickly due to low production of melanin - a natural substance that gives color (pigment) to hair, skin, and the iris of the eye. Melanin acts as natural sunscreen. Dark people, like black African American, on the hand, have a surplus of melanin to protect them in areas close to the equeator. If they live in more moderate zones on the planet, they need extra exposure to the sun to avoid skin cancer, prostate cancer, osteoporosis and other diseases that are linked with Vitamin D deficiency. Vitamin D levels increase with sunexposure. Pitta types have the least protection and to be on the safe side, they best avoid the hot sun.
Regarding sungazing during dawn and sunset, there can be no damage from that, because UV light is almost zero. However, if there are toxins in the face, around the eys, sinuses, etc., the sun may help release them and draw them out throgh the orifices of the eyes and pores of the skin. This can make the eyes exrete mucoid material along with dead yeast and other sticky, acidic material, and result in burning and blurred vision.
Regarding retinal damage, it is more often than not caused by acidic excretions than by the sun, usually due to gastro-intestinal and liver-related problems. Wearing sunglasses, and putting the poionsous chemcials contained in protective sun lotions on the body, especailly the face, is often enough to cause retinal damage. Sunglasses block out certain colors from the light spectrum, which leads to color deficiency in numerous cells of the body, including those that make up the eyes. The makes the eyes more vulnerable to injury, internal and external. With the prolonged use of sunglasses, the eyes become increasingly sensitive to sunlight(=tearing), and thus, progressively weaker. As a child, I used to be very sensitive to sunlight, and in the summer I had to wear sunglasses even indoors. After I cleansed my liver (living on the sun island of Cyprus), I stopped wearing sunglasses and after 3 months never had a problem again. And I spent most of my time outside. My eyes, have no retinal damage whatsoever. The eyes, consist of 99% water, and have great regenerative capacity when blood blow to and lymph drainage from the eyes are normal (more details on "Sunlight - Medicine of Nature" in my book Timless Secrets of Health & Rejuvenation,
http://www.ener-chi.com).
Andreas