A child is diagnosed with amblyopia in one eye. Which underlying process best explains this condition?
Degeneration of retinal photoreceptor cells.
Inflammation of the optic nerve.
Increased intraocular pressure damaging the optic nerve.
Suppression of visual input from one eye during development.
The Correct Answer is D
Choice D rationale
Amblyopia, often called lazy eye, occurs when the brain favors one eye over the other during the critical period of visual development. If one eye provides a blurry or misaligned image, the brain suppresses the input from that eye to avoid double vision or confusion. This lack of stimulation leads to permanent changes in the visual cortex. Early intervention is necessary because the brain eventually loses the ability to process signals from the suppressed eye if not corrected.
Choice A rationale
Degeneration of retinal photoreceptor cells is the primary mechanism for conditions like retinitis pigmentosa or macular degeneration. These disorders involve the physical breakdown of the cells that detect light and color in the eye. Amblyopia, however, is a functional disorder of the visual processing centers in the brain rather than a degenerative disease of the retina. In amblyopia, the eye structure and the retina are often completely healthy, but the brain ignores the signal.
Choice B rationale
Inflammation of the optic nerve, known as optic neuritis, causes acute vision loss and pain with eye movement. It is often associated with autoimmune conditions like multiple sclerosis. While it blocks the transmission of visual signals, it is an inflammatory process rather than a developmental suppression. Amblyopia is characterized by a lack of visual acuity development in childhood due to refractive errors or strabismus, not an acute inflammatory attack on the nerve fibers themselves.
Choice C rationale
Increased intraocular pressure damaging the optic nerve is the defining characteristic of glaucoma. This pressure causes mechanical damage to the nerve fibers, leading to peripheral vision loss and eventual blindness if untreated. Amblyopia does not involve elevated pressure within the eye. Instead, it is a neurological adaptation to poor quality visual input during the years when the brain is learning to interpret images, making it a developmental rather than a mechanical ocular disease. .
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A rationale
Type IV hypersensitivity is a delayed-type cell-mediated response involving T-lymphocytes rather than antibodies. This reaction typically takes 24 to 72 hours to manifest after exposure to an antigen. Common examples include contact dermatitis from poison ivy or a positive tuberculin skin test. Because the client in this scenario experienced symptoms within minutes, this cell-mediated mechanism does not explain the rapid onset of urticaria, wheezing, and life-threatening hypotension observed.
Choice B rationale
Type II hypersensitivity is an antibody-mediated cytotoxic reaction where IgG or IgM antibodies target specific antigens on cell surfaces. This leads to cell destruction through complement activation or phagocytosis. Classic examples include hemolytic transfusion reactions or Goodpasture syndrome. This process is generally tissue-specific and does not present with the systemic, multi-systemic rapid allergic features like wheezing and urticaria that are characteristic of the immediate IgE-mediated response described in the peanut allergy case.
Choice C rationale
Type I hypersensitivity is an immediate IgE-mediated reaction. Upon exposure to an allergen like peanuts, IgE antibodies bound to mast cells and basophils trigger the massive release of histamine and leukotrienes. This results in systemic vasodilation causing hypotension, increased capillary permeability causing urticaria, and bronchoconstriction causing wheezing. This reaction occurs within seconds to minutes of exposure. It represents the classic pathophysiological pathway for anaphylaxis, which matches all clinical findings presented.
Choice D rationale
Type III hypersensitivity involves the formation of antigen-antibody immune complexes that deposit in various tissues, such as blood vessel walls or kidneys. This deposition triggers complement activation and subsequent neutrophil-mediated inflammation. Examples include systemic lupus erythematosus or serum sickness. These reactions usually take several hours or days to develop. The pathophysiology of immune complex deposition does not align with the immediate, acute respiratory and cardiovascular collapse seen in this client's allergic reaction.
Correct Answer is D
Explanation
Choice A rationale
Giving an incompatible blood type never results in increased oxygen delivery to the tissues. Instead, the massive destruction of red blood cells significantly reduces the oxygen-carrying capacity of the blood. The resulting acute hemolytic transfusion reaction causes systemic instability and potential circulatory collapse. Oxygenation is further compromised by the formation of microemboli and the potential for acute lung injury, which are common complications of major ABO incompatibility errors.
Choice B rationale
The administration of incompatible blood triggers a massive, hyperactive immune response rather than suppression. The recipient's pre-existing antibodies immediately identify the foreign antigens on the donor cells, initiating a cascade of complement activation and inflammatory cytokine release. This leads to systemic symptoms such as fever, chills, and hypotension. Suppression of the immune system is generally an intentional therapeutic goal achieved through pharmacology, not a consequence of a mismatched blood transfusion.
Choice C rationale
A reaction is certain when type A blood receives type B blood because the recipient possesses naturally occurring anti-B antibodies. These antibodies are present in the plasma of any individual with type A blood and will recognize the B antigens on the donor erythrocytes. The interaction between the antigen and antibody is immediate and severe, making a "no reaction" scenario biologically impossible in a person with a functioning and healthy immune system.
Choice D rationale
When type B blood enters the circulation of a type A recipient, the anti-B antibodies in the recipient's plasma bind to the B antigens on the donor red blood cells. This causes agglutination, or clumping, of the cells. Following agglutination, the complement system is activated, leading to intravascular hemolysis where the red cells are ruptured. This releases hemoglobin into the plasma, which can cause acute renal failure and disseminated intravascular coagulation.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.