Retinoblastoma is the most common form of ocular cancer in children. It is derived from developing retinal cells. The most common symptoms are a white or yellow light reflex (also known as leukocoria), diminished pupillary reflex, crossing of the eyes, impaired vision, and bulging of the affected eye. A cataract may also cause the pupil to appear white or to produce a white or yellow light reflex, but it will not cause bulging of the eye.

A pinguecula is a fatty deposit on the sclera which will not alter the red-light reflex, and a hordeolum is outside the eye itself: it is an infection of a hair follicle of the eyelid, also known as a stye. 

A preterm infant cannot conserve heat due to several reasons. The infant has a lack of subcutaneous fat, has a large surface area relative to their body weight, a lack of glucose reserves, and a lack of brown fat - which is a unique type of fat that is capable of generating a greater amount of heat than just ordinary fat. 

In 21-hydroxylase deficiency, cortisol production is reduced, which in turn causes adrenocorticotropic hormone (ACTH) to increase. The precursors for the cortisol are then shunted into androgen production since these are steroids, and are thus derived from cholesterol.

Newborns should be placed on their back, in their crib, with nothing else when put to sleep. The crib may contain a fitted sheet or a light blanket. Crib pads, pillows, and stuffed animals are not advised because they may interfere with the child's ability to breathe.

Typically, the digestive system of a 2-day-old infant can only accommodate 15-30 milliliters of formula comfortably. The infant's stomach will grow considerably over the coming weeks. Frequent spitting up could be due to overfeeding. Before switching formula brands, try decreasing the amount fed at each feeding. Increasing the frequency of feedings may add to this problem. Another possibility, that the infant is feeding too fast, may be corrected by using a "slow-flow" instead of a "soft" or "standard" nipple. "Soft" nipples may be helpful in infants with poor suck or latch. While feeding and directly afterwards, it is advised to keep the infant in a semi-upright position.

Hippotherapy is therapeutic horseback riding for the handicapped. The motion of the horse can help the child develop flexibility and balance. Working with others and animals can help the child cross social and emotional boundaries. A therapy involving animals (pet therapy) is most similar to hippotherapy.

Diphtheria is an illness caused by bacteria (Corynebacterium diphtheriae). It is spread through droplets, requiring droplet precautions. Standard precautions should also be used, as with any patient. Delivery of antitoxin and antibiotics are important to a patient's recovery. Enforcing bedrest is important after a patient has developed myocarditis (inflammation of the heart).

Children under 4 years of age hold the greatest risk of contracting Pertussis and developing serious complications, including death. Pertussis vaccines are recommended for all age groups. Children can start a vaccination series as early as 2 months of age. New parents are encouraged to become vaccinated before their baby arrives to prevent transmission before the infant is eligible for immunization.

Measles is an airborne illness. For that reason, air pressure devices are necessary to prevent the spread of infection. Negative air pressure devices will adequately contain the measles virus because air will flow in to the room as opposed to out. Conversely, positive air pressure devices may be used to create an air flow out of a room in severely immunocompromised patients. 

Children and adults with exceptional personal hygiene are equally affected by head lice. The same applies to people of all socioeconomic groups, genders, and nationalities. All of the other options are true nursing interventions for head lice.