These abnormal blood vessels may grow up from the plane of the retina and may bleed inside the eye. When the blood and abnormal vessels are reabsorbed, it may give rise to multiple band like membranes which can pull up the retina, causing detachment of the retina and eventually blindness before 6 months.Normally, maturation of the retina proceeds in utero, and at term, the medial portion (Nasal retina) of the retina is fully vascularized, while the lateral portion (Temporal retina) is only incompletely vascularized. The normal growth of the blood vessels is directed to relatively low-oxygen areas of the retina, but the vessels remain in the plane of the retina and do not grow into the vitreous humor. If excess oxygen is given, normal blood vessels degrade and cease to develop. When the excess oxygen environment is removed, the blood vessels rapidly begin forming again and grow into the vitreous humor of the eye from the retina.The key disease element in ROP is fibrovascular proliferation. This is growth of abnormal new vessels; this may regress, but frequently progresses. Associated with the growth of these new vessels is fibrous tissue (scar tissue) that may contract to cause retinal detachment. Multiple factors can determine whether the disease progresses, including overall health, birth weight, the stage of ROP at initial diagnosis, and the presence or absence of "plus disease". Supplemental oxygen exposure, while a risk factor, is not the main risk factor for development of this disease.
A carbuncle is a cluster of boils caused by bacterial infection, most commonly with Staphylococcus aureus or Streptococcus pyogenes. The presence of a carbuncle is a sign that the immune system is active and fighting the infection. The infection is contagious and may spread to other areas of the body, or other people; those living in the same residence may develop carbuncles at the same time. In the early 21st century, infection involving methicillin-resistant Staphylococcus aureus (MRSA) has become more common. Signs and symptoms
A carbuncle is a cluster of several boils, which is typically filled with purulent exudate (dead neutrophils, phagocytized bacteria, and other cellular components). Fluid may drain freely from the carbuncle, or intervention involving an incision and drainage procedure may be needed. Carbuncles may develop anywhere, but they are most common on the back and the nape of the neck.A carbuncle is palpable and can range in size to be as small as a pea or as large as a golf ball. The surrounding area is indurated. Later, skin on the centre of the carbuncle softens and peripheral satellite vesicles appear, which rupture discharging pus and give rise to cribriform appearance. As the impending infection develops, itching may occur. There may be localized erythema, skin irritation, and the area may be painful when touched. Sometimes more severe symptoms may occur, such as fatigue, fever, chills, and general malaise as the body fights the infection. Cause
The initial cause of a carbuncle can often not be determined.