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Upwards VS. downward lens dislocations!

A dislocated lens (ectopic lens) is a lens that has moved out of position as a result of disruption of the ciliary body zonules that hold the lens in place. Some people are born with conditions that can cause weak ligaments and are prone to having a dislocated lens. For example, about half of the patients with Marfan syndrome, in which there is a defect in fibrillin gene and normal connective tissue function is disrupted, develop upward dislocated lenses (the top photo), as well as joint hypermobility, tall stature, scoliosis/kyphosis, long fingers (arachnodactyly) and tendency toward aortic wall aneurysms and ruptures. A downward dislocated lens (bottom photo) is very typical for a condition called Homocystinuria. Homocystinuria is an inherited disorder that affects the metabolism of the amino acid methionine, resulting in the accumulation of homocystine. It is associated with cardiovascular disease, deep vein thrombosis, thromboembolism, and stroke. Intellectual disability and ectopic lens do occur too. The main differentiating feature is lens dislocation that is downward rather than upward. Generally, there is no pain associated because the lens lacks sensory innervation. If a lens dislocation blocks aqueous drainage from the eye, there may be an acute rise in intraocular pressure. If this occurs, the patient may complain of nausea, intense eye pain, headache, vomiting, and blurred vision.