Anterior Lenticonus - Symptoms, Diagnosis, and Treatment

Introduction

The eye is divided into an anterior chamber and a posterior chamber. The anterior chamber is the front portion of the eye where the clear fluid called aqueous humor circulates and provides nutrients to the eye. The anterior chamber consists of the following parts.

• Cornea: The dome-shaped clear surface covering the front portion of the eye is called the cornea.

• Iris: The part of the eye which is colored and regulates the amount of light that enters the eye is called the iris.

• Lens: It is the transparent structure that acts as the focusing lens that helps to focus light beams onto the retinal layer located on the inside and back of the eye. It is also called a crystalline lens. It is present behind the pupil. The lens changes its shape to focus on different objects. A capsule is present that surrounds the lens called a lens capsule.

• Pupil: The gap or opening in the center of the iris is called the pupil and light enters into the back of the eye through the opening.

• Retina: It is the nerve lining on the inside of the eye at the back. It is sensitive to light and is responsible for sensing light and transmitting impulses to the brain through the optic nerve.

• Sclera: The white part of the eyeball is called the sclera. The muscles that help in the movement of the eyeball are attached to the sclera.

What Is Meant by the Term Anterior Lenticonus?

When the front portion of the crystalline lens takes up the shape of a cone, it is called anterior lenticonus. The actual conical protrusion is located on the lens capsule and cortex beneath it. The protrusion can be 2 to 7 mm in diameter. If the shape of the protrusion is spherical, it is known as lentiglobus. Based on the location of conical projection, it can be of two types.

• Anterior Lenticonus: If the conical protrusion is in the front part of the lens it is called an anterior lenticonus. This is seen in syndromes like Alport syndrome and Waardenburg syndrome.

• Posterior Lenticonus: If the conical protrusion is in the back part of the lens, it is called posterior lenticonus. It is more common in occurrence and seen in Lowe syndrome.

What Are the Clinical Features of the Anterior Lenticonus?

• Anterior thinning of the affected capsule is prevalent.

• Epithelial deficiency is present below the lens capsule.

• Irregular astigmatism (an imperfect eye curvature) results due to epithelial deficiency.

• It is associated with Alport syndrome or presents as an isolated feature.

• Anterior lenticonus can be unilateral or bilateral. A bilateral condition is observed in Alport syndrome.

• A sudden rupture of the lens capsule is seen.

What Is Alport Syndrome?

It is an inherited disorder of kidneys characterized by inflammation called nephritis. It is caused due to a genetic mutation that codes for a protein in collagen(connective tissue). There are three types of Alport syndrome.

1. X-linked Alport Syndrome (XLAS): It is the most commonly seen type of Alport syndrome and males are more severely affected than females.

2. Autosomal Recessive Alport Syndrome (ARAS): It is prevalent equally in males and females with equal severity.

3. Autosomal Dominant Alport Syndrome (ADAS): This type is rare and males and females are affected with the same severity of the disease.

The clinical manifestations affecting the eye are as follows:

• Along with kidney problems, individuals affected by this syndrome have eye problems such as anterior lenticonus which can lead to vision impairment and cataracts.

• There is an erosion of the corneal layer leading to the loss of the outer layer of the eyeball. This causes redness, itchiness, pain, and blurred vision.

• Dot-And-Fleck-Retinopathy: There are yellowish or white flecks of pigmentation of the retina which does not affect the vision but can help diagnose the syndrome.

• There is thinning or gap in the macula called a macular hole. The macula is the part of the retina that helps in central vision and makes it sharper and more detailed. This can cause blurred central vision.

How Is Anterior Lenticonus Diagnosed?

• Biomicroscopy: Lenticonus presents as a localized transparent and sharp conical protrusion of the lens capsule and underlying cortex.

• Retro-Illumination: Using a narrow slit, the lenticonus is observed. It shows opacities in the capsule and the cortex when the lenticonus is severe. But during the early stages, the illumination shows oil droplet structures. When the retina is observed under a microscope, the oil droplets make scissor movement of the light reflex, which is pathognomonic for the disease.

• Ultrasonography: This can also be used to demonstrate lenticonus. Two types of scans are used. A-scan ultrasonography reveals the increased thickness of the lens and A B-scan ultrasonography shows herniation of lenticular substance.

How Is the Anterior Lenticonus Treated?

The surgical treatment for anterior lenticonus is phacoemulsification and intraocular lens implantation under general anesthesia. It is an excellent choice of surgical treatment for anterior lenticonus.

• Phacoemulsification means advanced cataract surgery to eliminate the clouding of the lens caused due to anterior lenticonus.

• This surgery uses an ultrasonic machine that produces ultrasonic waves to crush the damaged lens into smaller pieces and a vacuum is used to suck out the broken pieces.

• It restores vision by replacing the damaged lens with an artificial lens.

• The advantages of this procedure are that it's less invasive, and quick, and the lens replaced is more stable than others in other surgeries.

• The artificial lens replacement in the eye after removing the natural lens is called intraocular lens implantation (IOL).

• Clear Lens Extraction: It is the process of removing the eye’s natural lens to replace it with a synthetic one.

• Capsulorhexis: It is a technique used in capsulotomy (incision made in the lens capsule) to remove the anterior part of the lens capsule. The incision is made in a circular pattern along the periphery of the lens.

Conclusion

Anterior lenticonus is an acquired condition. It occurs as a part of Alport syndrome. Anterior lenticonus is often overlooked or goes unnoticed. It is a helpful tool in diagnosing systemic diseases like Alport syndrome. Careful clinical evaluation by an ophthalmologist helps in early and accurate diagnosis and helps the surgeon choose the appropriate surgical therapy.