A retrolisthesis is a posterior displacement of one vertebral body with respect to the subjacent vertebra to a degree less than a luxation (dislocation). Retrolistheses are most easily diagnosed on lateral x-ray views of the spine. Views where care has been taken to expose for a true lateral view without any rotation offer the best diagnostic quality. Retrolistheses are found most prominently in the cervical spine and lumbar region but can also be seen in the thoracic area. Classification
Retrolisthesis can be classified as a form of spondylolisthesis, since spondylolisthesis is often defined in the literature as displacement in any direction. Yet, medical dictionaries usually define spondylolisthesis specifically as the forward or anterior displacement of a vertebra over the vertebra inferior to it (or the sacrum). Retrolisthesis is also called retrospondylolisthesis. Signs and symptoms
Retrolisthesis may lead to symptoms of greatly varying intensity and distribution. This is because of the variable nature of the impact on nerve tissue and of the mechanical impact on the spinal joints themselves.Structural instability may be experienced as a local uneasiness through to a more far reaching structural compensatory distortion involving the whole spine. If the joints are stuck in a retrolisthesis configuration there may also be changes to range of motion.Pain may be experienced as a result of irritation to the sensory nerve roots by bone depending on the degree of displacement and the presence of any rotatory positioning of the individual spinal motion segments. The soft tissue of the disc is often caused to bulge in retrolistheses.
Leucomatous corneal opacity (leucoma simplex)
Leucomatous corneal opacity is a dense white opacity which results due to scarring of more than half of the stroma. A number of different presentations of leucomatous corneal opacity exist:

Adherent leucoma: results when healing occurs after perforation of cornea with incarceration of iris. The iris is adherent to the back of a leucomatous cornea. One of the major complication of adherent leucoma is Secondary glaucoma
Corneoiridic scar: if iris tissue is incarcerated and incorporated within the scar tissue, as occurs in healing of a large sloughed corneal ulcer, it is called a corneoiridic scar. Corneal facet: corneal surface depressed at the site of healing (due to less fibrous tissue); such a scar is called facet. Kerectasia: In this condition, corneal curvature is increased at the site of opacity (bulge due to weak scar). Presentation
Signs and symptoms include the following:

Loss of vision or blindness (when dense opacity covers the pupillary area)
Blurred vision (due to astigmatic effect and light scattering)
Glare

Complications
Congenital corneal opacity that affecting vision will cause amblyopia. That type of amblyopia is known as form-deprivation amblyopia (or amblyopia ex anopsia). Secondary changes in corneal opacity
Secondary changes may be seen in long-standing cases include: hyaline degeneration, calcareous degeneration, pigmentation and atheromatous ulceration. Causes
Congenital opacities may occur as developmental anomalies or following birth trauma. Causes of congenital corneal opacities include sclerocornea, trauma, ulcer, mucopolysaccharidosis, Peter’s anomaly, congenital hereditary endothelial dystrophy. Ocular trauma 
Corneal ulceration 
Xerophthalmia, caused by Vitamin A deficiency
Trachoma
Onchocerciasis
Mucous membrane pemphigoid: Ocular form of mucous membrane pemphigoid may cause corneal opacity and loss of vision.