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NBME 23 Answers

nbme23/Block 2/Question#43

A 2-week-old girl is brought to the physician by ...

Iris

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submitted by hayayah(447),

Coloboma is an eye abnormality that occurs before birth. They're missing pieces of tissue in structures that form the eye.

  • Colobomas affecting the iris, which result in a "keyhole" appearance of the pupil, generally do not lead to vision loss.

  • Colobomas involving the retina result in vision loss in specific parts of the visual field.

  • Large retinal colobomas or those affecting the optic nerve can cause low vision, which means vision loss that cannot be completely corrected with glasses or contact lenses.

mousie  thanks for this explanation! +  
macrohphage95  can any one explain to me why not lens ? +  
krewfoo99  @macrophage95 Lens are an interal part of the refractive power of the eye. Without the lens the image would not be formed on the retina, thus leading to visual loss +1