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Intercostal retractions occur when the muscles between the ribs pull inward. The movement is most often a sign that the person has a breathing problem. Intercostal retractions are a medical emergency.
Refractive Shifts Due to Cataracts. Advanced nuclear cataract. â tends to increase the thickness of the center of the lens. -> lens resembles plus lens. -> more likely to cause myopic shift. Cortical Cataract. â tends to increase thickness of edges of lens. -> resembles minus lens. -> more likely to cause hyperopic shift.