Lenticonus (/len·ti·co·nus/ (len″tĭ-ko´nus)) ens + L. conus, coneis a rare

congenital anomaly A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth def ...

of the

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

characterized by a conical protrusion on the crystalline

lens capsule The lens capsule is a component of the Globe (human eye), globe of the Human eye, eye. It is a clear elastic basement membrane similar in composition to other basement membranes in the body. The capsule is a very thick basement membrane and the t ...

and the underlying cortex. It can reach a diameter of 2 to 7 mm. The conus may occur anteriorly or posteriorly. If the bulging is spherical, instead of conical, the condition is referred to as ''lentiglobus''. It produces a decrease in

visual acuity Visual acuity (VA) commonly refers to the clarity of visual perception, vision, but technically rates an animal's ability to recognize small details with precision. Visual acuity depends on optical and neural factors. Optical factors of the eye ...

and irregular refraction that cannot be corrected by either spectacle or contact lenses. Biomicroscopically ''lenticonus'' is characterized by a transparent, localized, sharply demarcated conical projection of the lens capsule and cortex, usually axial in localization. In an early stage, retro-illumination shows an oil droplet configuration. Using a narrow slit, the image of a conus is observed. In a more advanced stage associated subcapsular and cortical opacities appear. Retinoscopically the oil droplet produces a

pathognomonic Pathognomonic (synonym ''pathognomic'') is a term, often used in medicine, that means "characteristic for a particular disease". A pathognomonic sign is a particular sign whose presence means that a particular disease is present beyond any doubt. ...

scissors movement of the light reflex. This phenomenon is due to the different refraction in the central and the peripheral area of the lens.

Ultrasonography Medical ultrasound includes diagnostic techniques (mainly imaging) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, ...

also can illustrate the existence of a ''lenticonus''. A-scan ultrasonography may reveal an increased lens thickness and B- scanultrasonography may show herniated lenticular material, suggestive of a lenticonus.

Amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...

cataract A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...

strabismus Strabismus is an eye disorder in which the eyes do not properly align with each other when looking at an object. The eye that is pointed at an object can alternate. The condition may be present occasionally or constantly. If present during a ...

and loss of central fixation may be observed in association with lenticonus posterior. Cataract, flecked

retinopathy Retinopathy is any damage to the retina of the eyes, which may cause vision impairment. Retinopathy often refers to retinal vascular disease, or damage to the retina caused by abnormal blood flow. Age-related macular degeneration is technically in ...

, posterior polymorphous dystrophy and corneal arcus juvenilis may be encountered in association with lenticonus anterior that occurs as a part of the Alport syndrome.Jacobs K., Meire F.M. ''Lenticonus''. Departement of Ophthalmology, Ghent University Hospital; Bull. Soc. belge Ophtalmol., 277, 65-70, 2000 - www.ophthalmologia.be/download.php?dof_id=74 There exist two distinct types of ''lenticonus'' based on the face of the lens affected.

Types

# Lenticonus anterior; lenticonus anterior is part of the

waardenburg syndrome Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or Heterochromia iridum, one blue eye and one brown ey ...

# Lenticonus posterior; lenticonus posterior is more common than lenticonus anterior and is sometimes found in

Lowe syndrome Oculocerebrorenal syndrome (also called Lowe syndrome) is a rare X-linked recessive disorder characterized by congenital cataracts, hypotonia, intellectual disability, proximal tubular acidosis, aminoaciduria and low-molecular-weight proteinur ...

Alport syndrome mostly causes anterior lenticonus. It can rarely cause posterior lenticonus, but this is uncommon.

References

{{Reflist Ophthalmology