Clinical Features
Spherophakia
Also known as microphakia, spherophakia is often bilateral. The lens appears spherical, with a smaller diameter and a longer anteroposterior axis. After full pupil dilation, the equatorial region of the lens and the zonular fibers become fully exposed. Due to laxity of the zonular fibers, the lens may shift anteriorly, increasing the risk of pupillary block and leading to angle-closure glaucoma. The use of miotic agents can induce ciliary muscle contraction, further loosening the zonular fibers, causing the lens to shift forward and exacerbating the pupillary block.
The spherical shape of the lens increases its refractive power, potentially resulting in high myopia. Subluxation of the lens is common, and complete dislocation may also occur in some cases. Reduced tension on the elongated zonular fibers leads to a lack of accommodative function.
Lenticonus
The anterior or posterior surface of the lens protrudes in a conical shape, typically due to cortical protrusion. This condition often arises in the late fetal period or after birth. Lenticonus is a rare congenital lens anomaly, with anterior lenticonus being even rarer. It is frequently associated with congenital cataracts and high myopia.
Lens Coloboma
This condition is often unilateral but can also be bilateral. A notch-like defect of variable size and shape is present in the inferomedial equatorial region of the lens. The area of the defect shows reduced or absent zonular fibers. Uneven refractive power in different directions leads to myopic astigmatism.
Lens Pit Defect
This is an extremely rare anomaly characterized by a small depression on the anterior or posterior surface of the lens.
Diagnosis
The diagnosis is based on lens morphology observed under a slit-lamp microscope.
Treatment
Treatment is generally unnecessary in asymptomatic cases or in the absence of complications. Miotic agents are contraindicated in spherophakia. Surgical intervention may be considered in cases of lens dislocation or cataracts. In cases with amblyopia, prompt management of amblyopia is recommended.