The scallop Pecten has up to 100 millimetre-scale reflector eyes fringing the edge of its shell. It detects moving objects as they pass successive lenses.There is at least one vertebrate, the spookfish, whose eyes include reflective optics for focusing of light. Each of the two eyes of a spookfish collects light from both above and below; the light coming from above is focused by a lens, while that coming from below, by a curved mirror composed of many layers of small reflective plates made of guanine crystals. Compound eyes
A compound eye may consist of thousands of individual photoreceptor units or ommatidia (ommatidium, singular). The image perceived is a combination of inputs from the numerous ommatidia (individual "eye units"), which are located on a convex surface, thus pointing in slightly different directions. Compared with simple eyes, compound eyes possess a very large view angle, and can detect fast movement and, in some cases, the polarisation of light. Because the individual lenses are so small, the effects of diffraction impose a limit on the possible resolution that can be obtained (assuming that they do not function as phased arrays). This can only be countered by increasing lens size and number. To see with a resolution comparable to our simple eyes, humans would require very large compound eyes, around 11 metres (36 ft) in radius.Compound eyes fall into two groups: apposition eyes, which form multiple inverted images, and superposition eyes, which form a single erect image. Compound eyes are common in arthropods, annelids and some bivalved molluscs.
Photodermatitis, sometimes referred to as sun poisoning or photoallergy, is a form of allergic contact dermatitis in which the allergen must be activated by light to sensitize the allergic response, and to cause a rash or other systemic effects on subsequent exposure. The second and subsequent exposures produce photoallergic skin conditions which are often eczematous. It is distinct from sunburn. Signs and symptoms
Photodermatitis may result in swelling, difficulty breathing, a burning sensation, a red itchy rash sometimes resembling small blisters, and peeling of the skin. Nausea may also occur. There may also be blotches where the itching may persist for long periods of time. In these areas an unsightly orange to brown tint may form, usually near or on the face. Causes
Many medications and conditions can cause sun sensitivity, including:

Sulfa used in some drugs, among them some antibiotics, diuretics, COX-2 inhibitors, and diabetes drugs. Psoralens, coal tars, photo-active dyes (eosin, acridine orange)
Musk ambrette, methylcoumarin, lemon oil (may be present in fragrances)
PABA (found in sunscreens)
Oxybenzone (UVA and UVB chemical blocker also in sunscreens) 
Salicylanilide (found in industrial cleaners)
St Johns Wort
Hexachlorophene (found in some prescription antibacterial soaps)
Tetracycline antibiotics (e.g., tetracycline, doxycycline, minocycline)
Benzoyl peroxide
Retinoids (e.g., isotretinoin)
Some NSAIDs (e.g., ibuprofen, naproxen sodium)
Fluoroquinolone antibiotic: Sparfloxacin in 2% of cases
Amiodarone, used to treat atrial fibrillation
PellagraPhotodermatitis can also be caused by plants such as Ammi majus, parsnip, giant hogweed (Heracleum mantegazzianum), common rue (Ruta graveolens), and Dictamnus, a genus of flowering plants in the family Rutaceae with a single species Dictamnus albus, commonly called the burning bush.