What is Pigment Dispersion Syndrome & How is it Treated?
Eyes are a very important part of our body and essential for our proper functioning. It is only through them that we can see and perceive the world and live a meaningful life. Without our sense of seeing, we are nothing. The disease of the eye affects its normal functions and makes our life difficult. Hence, we need to be alert about the different eye diseases and take good care of them. Among the various eye diseases, occurrence of Pigment dispersion syndrome (PDS), which is an eye disorder, is very rare.
What is Pigment Dispersion Syndrome?
The colour of the eye is due to the presence of a pigment in the iris. In case of Pigment dispersion syndrome, this pigment is released from iris and it floats in the aqueous humour and clogs the trabecular meshwork. This prevents the flow of aqueous humour and builds pressure inside the eye which affects the optic nerve leading to pain in eye and blurring of vision.
Signs and Symptoms of Pigment Dispersion Syndrome
The early stages of Pigment dispersion syndrome are asymptomatic; therefore it is difficult to know if the person is affected. Later there is loss of peripheral vision and in advanced stages there is loss of central vision. During these stages,
- Pain is felt in the eye
- Coloured halos are observed
- Blurred vision.
Signs of Pigment Dispersion Syndrome
- It shows a characteristic Krunkenberg spindle. This is a vertical spindle due to pigment deposition on the epithelium of the cornea. It appears as a central vertical brown band. However, this may not be always characteristic of Pigment dispersion syndrome.
- Slit like radial
- Iris Transillumination Defects (ITDs)
- Heavy Trabecular Meshwork pigmentation
- Other ocular findings are relatively flat cornea, deep anterior chamber and wide open angles.
Epidemiology of Pigment Dispersion Syndrome
The incidence of pigment dispersion syndrome is thought to be 4.8 per 100,000 of the population. It has increased incidence in the Caucasian population. Mostly men are affected, but it is also observed in women. The onset of pigment dispersion syndrome is between 20-40 years. Most of these patients have myopia or near sighted. A typical pigment dispersion syndrome patient is a young white myopic male. It is bilateral and there is no typical hereditary pattern noticed. Most of the cases are sporadic. It is an autosomal dominant disorder with genetic markers found on chromosome 7q35-36.
Prognosis of Pigment Dispersion Syndrome
If untreated, pigment dispersion syndrome may result in Pigmentary Glaucoma which leads to blindness. If diagnosed in early stages then controlling pigment dispersion syndrome is much better than in later stages.
Causes of Pigment Dispersion Syndrome
Pigment dispersion syndrome is a rare condition. Hence, the exact cause for this disease is still unknown. Most of the cases are sporadic and the genetic linkage or inheritance pattern has not yet been clearly established.
One of the possible cause due to which pigment dispersion syndrome develops is that some people have unique anatomy of eye which causes the lens zonules (fibres) to rub against the back of the iris. This releases the pigment from iris which leads to pigment dispersion syndrome. It has been speculated that athletes who play basketball or are in excessive physical activity have an increased incidence of pigment dispersion syndrome.
Pathophysiology of Pigment Dispersion Syndrome
Pigment dispersion results due to release of pigment from the iris which floats to the aqueous humour. Over the time, large amounts of this pigment accumulate in different parts of the anterior chamber such as corneal endothelium, iris surface, trabecular meshwork (TM), lens surface and zonula. Aqueous fluid which is continuously produced by the eye normally flows out of the eye through its drainage system called trabecular meshwork. The pigment clogs the fine trabecular meshwork and prevents the draining of aqueous humour. This leads to increase in intraocular pressure and starts affecting the optic nerve fibres. When the pressure is high enough to damage the optic nerve it is called as pigmentary glaucoma. In the long term, this leads to irreversible loss of the vision.
Risk Factors of Pigment Dispersion Syndrome
Some of the risk factors for pigment dispersion syndrome are:
- Pigment dispersion syndrome is common in Caucasian males
- Males who are young in the age range of 20-40 years and have myopia. Myopia results in increased depth of anterior chamber which increases the contact between iris and lens fibres leading to pigment dispersion syndrome.
Complications of Pigment Dispersion Syndrome
Pigment dispersion syndrome is not fatal. However, when the pressure inside the eye continues to increase, it starts affecting the optic nerve which leads to a condition called pigmentary glaucoma. The pigmentary glaucoma then progresses to irreversible loss of vision. The probability of conversion of pigment dispersion syndrome to pigmentary glaucoma is 10% in 5 years and 15% in 15 years.
Diagnosis of Pigment Dispersion Syndrome
Diagnosis of pigment dispersion syndrome is done by the ophthalmologist and optometrist in two to three visits. They examine the eyes, cornea and iris. They perform visual testing and measurements of visual field and eye pressure.
- Slit Lamp Biomicroscopy to Diagnose Pigment Dispersion Syndrome: Slit lamp Biomicroscopy is used to focus thin beam of light on the corneal endothelium to observe the presence of brown granulated bands (Krukenberg spindle). The posterior location of the iris and its concave configuration is also observed by using the biomicroscope or optical concave tomography (OCT). By using small slit beam perpendicular to the plane of the iris, the doctor examines in the dark room, the "transillumination of the iris". Due to the lack of pigment in the iris, the doctor observes slit like defects.
- Gonioscopy Test to Identify Pigment Dispersion Syndrome: Further, Gonioscopy test is done to clearly observe the angle of the eye's drainage and observe if the trabecular meshwork is clogged with the pigment. Other procedures are performed to check if there are signs of pigment floating in the eyes.
The posterior segment is crucial in pigment dispersion and has to be carefully examined. The frequency of lattice degeneration is higher in these patients and there is retinal detachment too.
- By pupil dilation, the back of the eyes including the optic nerve is examined.
- If pigmentary glaucoma has developed, then signs and symptoms of glaucoma is also checked.
Treatment of Pigment Dispersion Syndrome
The proper management of pigment dispersion syndrome is done as follows:
- Regular eye check from a doctor
- Beta blockers are prescribed to reduce the increased pressure present in the eye.
- Surgical treatment to improve the drainage of the eye's fluid. Aqueous shunt surgery, Trabeculectomy and peripheral iridectomy are performed depending on the requirement.
- Laser iridotomy, a laser treatment to improve the flow of aqueous humour to the trabecular meshwork can be done.
- Laser trabeculoplasty is used to treat open-angle glaucoma.
Prevention of Pigment Dispersion Syndrome
- The Pigment dispersion syndrome affected person is advised not to engage in extreme sports.
- To prevent complications of pigment dispersion syndrome, regular eye check from eye doctors should be done.
Pigment dispersion syndrome is a rare disorder of the eye. If diagnosed early, then to some extent, it is treatable. With further research about its pathophysiology and with improved treatment modalities, the patient with pigment dispersion syndrome will have better quality of life.