Pigmentary glaucoma: What is it? 

When the optic nerve is harmed by pigment dispersion syndrome, pigmentary glaucoma (PG) is detected. Although we will examine pigmentary glaucoma in this post, it is important to note that some people may have pigment dispersion without having glaucoma. 

Because this type of glaucoma can be a sneaky condition with no symptoms, it is especially alarming that it is typically discovered in the third or fourth decade of life which is quite young for most types of glaucoma.

Pigmentary glaucoma tends to affect more men than women, myopic individuals, and people who are younger (20-40 years old). Even while pigmentary glaucoma can occur without a family history, it is occasionally a sign of the condition.

Pigmentary Dispersion Syndrome

A spectrum of the same condition, pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG), is defined by excessive pigment liberation across the anterior portion of the eye. The traditional trio consists of pigment deposition on the posterior side of the central cornea, mid-peripheral iris transillumination deficiencies, and intense trabecular meshwork pigmentation. In pigment dispersion syndrome and pigmentary glaucoma, pigment deposition in the trabecular meshwork limits the aqueous outflow facility and may cause an increase in intraocular pressure (IOP) as well as optic nerve injury and visual field loss. When pigment flakes off from the iris as a result of the posterior iris rubbing against the anterior lens zonules, pigmentary glaucoma and PDS develop. Males are more likely to get the condition, which commonly manifests in the third or fourth decade of life.

How Common is Pigmentary Dispersion Glaucoma and Pigmentary Dispersion Syndrome?

A kind of secondary open-angle glaucoma known as pigmentary glaucoma is characterized by severe homogeneous trabecular meshwork pigmentation, iris transillumination abnormalities, and pigment along the middle of the corneal endothelium (Krukenberg spindle). Even if the IOP is excessive, those with these same results who do not have optic nerve injury and/or visual field loss are diagnosed as having PDS. It is unclear how common PDS and PG are in the general population. Approximately 15% of PDS patients may exhibit elevated IOP or develop glaucoma after a period of roughly 15 years. It is an autosomal dominant disorder with a wide range of genetic loci and varying penetrance. When New York City employees were screened, it was discovered that 2.5% of them had at least one slit lamp finding that was consistent with PDS, and when glaucoma practice files were retrospectively reviewed, it was found that 1 in 25 patients (4%) were monitored for either PDS or PG. The yearly incidence of diagnosed PDS and PG in Olmstead County, Minnesota, was 4.8/100,000 and 1.4/100,000, respectively. The actual numbers are most likely much higher because many PDS and PG patients may have had the unrecognized illness.

Etiology 

Concave iris contours allow the posterior iris surface to rub against the anterior lens zonule bundles during physiological pupil movement, disrupting the iris pigment and releasing pigment granules as the underlying process for PDS and PG. Granules of pigment can temporarily raise IOP by obstructing the trabecular meshwork and decreasing outflow. Chronic rise of IOP and secondary glaucoma may result from pathological alterations in the collagen beams and trabecular endothelial cells over time, which can increase resistance to aqueous outflow. In comparison to healthy controls, patients with PDS or PG have an anterior chamber that has a 15-fold greater quantity of aqueous pigment granules.

The diagnosis of pigmentary glaucoma 

Most often, especially early in the course of the disease, many people do not exhibit symptoms. Similar to open-angle glaucoma, patients with pigmentary glaucoma may develop side vision problems as the disease progresses. Rarely, patients may have intermittent haloes or visual blur. Your eye doctor must do a complete examination of your eyes, including a review of your drainage angle, in order to make a diagnosis of pigmentary glaucoma. 

Patients with pigmentary glaucoma or pigment dispersion have more pigment in the drainage angle than normal. Additionally, they could have pigment on the cornea’s inner lining and iris thinning where the iris chafes and releases pigment. In order to determine whether there is any optic nerve injury, a thorough examination of the posterior of the eye is also required. To check for side vision issues, you could go through a formal field of vision testing and optic nerve imaging.

Who’s at risk?

Gender of the patient: All case series with pigmentary glaucoma demonstrate a male-to-female ratio of between 2:1 and 5:1 in favor of the male gender. For PDS, there is far less of a male preponderance, with case series indicating male-to-female ratios of 1:1 to 2:1. 

Age

Patients with PG and PDS tend to appear when they are in their 30s, whereas women generally do so around a decade later in life. PDS cases have been seen in people as young as 12 to 15 years old. In middle age, when the lens has grown and the iris is flexible enough to assume a concave posture, the disease may be more common. 

Myopia

With mean spherical equivalents often falling between -3 and -4 D, mild myopia is the most frequent refractive defect seen in eyes with PDS and PG. Although hyperopia is extremely uncommon, often accounting for about 5–10% of patients in most case series, a wide variety of refractive abnormalities are typically seen. 

Race

People of African descent are more likely than other races to experience the rare pigment dispersion syndrome and PG (5% of individuals in case series). However, due to their thick brown irides, which make it more challenging to identify iris transillumination deficiencies, people of African heritage may have a higher incidence than that which has been recorded. 

Patients with PDS and PG have more iridolenticular contact than people without the condition. They also have posterior iris insertions that are concave. Concave iris and more posterior iris insertion, both occur more in individuals with PDS or PG, together resulting in increased iridolenticular contact. 

Flat corneas

In comparison to control participants of the same age and refractive error, patients with PDS and PG have much flatter corneas. When you blink, the aqueous fluid may burp from the posterior chamber to the anterior chamber more often with a flat cornea, increasing iridozonular contact. 

Family history

A small group of PDS patients’ relatives was directly examined, and it was discovered that 2/19 (12%) of them had the condition. It was discovered during a second family analysis that 36% of the subjects’ parents and 50% of their siblings had PDS, although none of the individuals had children. This finding raises the possibility of an incomplete penetrance autosomal dominant inheritance pattern. Multiple generations of families with PG have also been documented. The concept of an autosomal dominant inheritance pattern was reinforced by the discovery that around 50% of family members in the studied families had PDS or PG. 

The following are risk factors for disease progression or disease stage progression: 

Intraocular pressure was identified as the sole risk factor for PDS to PG advancement in retrospective research from Olmstead County, Minnesota. Family history, age, and refractive error were not linked to conversion to PG. 

iris-lens contact in individuals with the asymmetric disease was shown to be higher in the more afflicted eye than the less affected eye. Patients with PDS or PG also had a higher prevalence of characteristics that increased iridolenticular contacts, such as larger iris concavity and more posterior iris insertion. 

Greater trabecular meshwork pigmentation: When PDS is present in both eyes, the eye with the more pigment in the trabecular meshwork usually has the worst pathology.

Treatment of pigmentary dispersion glaucoma

Depending on how pigment dispersion syndrome affects your eye pressure (also known as intraocular pressure, IOP), there are many treatments available: 

The risk of optic nerve injury is modest in pigment dispersion syndrome with normal or hardly raised IOP. Other than visiting your ophthalmologist once a year, there is no therapy required. Your IOP will be checked, and he or she will keep an eye out for any changes in your vision. 

The risk of optic nerve injury is higher in pigment dispersion syndrome with excessive IOP. You could receive laser treatment or prescription eye drops to decrease IOP. 

Pigmentary glaucoma is the term used when the IOP from PDS is so high that it harms the optic nerve. In this situation, treatment is required, which may consist of laser therapy, surgery, or prescription eye drops.

Medication 

Pigmentary glaucoma is treated with the same drugs that are used to treat open-angle glaucoma. Some recommend utilizing pilocarpine, an older glaucoma drug that has the potential to change the structure of the eye and reduce friction and pigment dispersion. However, pilocarpine has a number of negative side effects, including a higher risk of retinal detachment, which is already somewhat more likely in nearsighted individuals with pigmentary glaucoma. 

Laser Therapy 

The effectiveness of a laser operation to create a tiny hole in the iris, which is often used to prevent or cure angle-closure glaucoma, is a topic of debate. In the case of pigmentary glaucoma, the hole’s function is to assist reposition the eye’s structure, resulting in less iris rubbing or chafing and less pigment dispersion. 

Because there is more pigment in the drainage angle in pigmentary glaucoma, a new kind of laser (laser trabeculoplasty) can also be utilized to enhance drainage and decrease pressure. Finally, more severe cases of pigmentary glaucoma can also be treated surgically using techniques like trabeculectomy or tube shunt surgery.

Prognosis 

Rarely does PG cause blindness. One patient in a community-based study of 113 PDS and PG patients who were followed for a median of 6 years had unilateral blindness, while another developed bilateral blindness. Although 23% of patients were recognized to have PG upon diagnosis, 10% of PDS patients advanced to PG after 5 years and 15% at 10 years, according to the same research. Over a mean follow-up period of 6 years, 44% of patients with PG had impairment of their visual fields. In a group of patients being monitored in a glaucoma clinic, similar rates of blindness were discovered; however, greater rates of progression from PDS to PG were noted (35% during a median follow-up of 15 years), and almost 40% of PG patients were found to have deteriorating optic nerve damage. The only known risk factor for progression is increased intraocular pressure. PG may occasionally regress with time. Defects in iris transillumination and TM pigmentation have both been seen to return to normal over time. Even increased IOP has been seen to revert to normal, pointing to the resumption of healthy TM function. The presence of thick TM pigmentation and iris transillumination abnormalities in older individuals with diagnoses of normal tension glaucoma suggests they may have had PG with later normalization of IOP as a result of the cessation of pigment release. The “pigment reversal sign,” which is present in these individuals, aids in identifying the various kinds of glaucoma.

Summary 

Pigmentary glaucoma can go undiagnosed since it can have no symptoms and because it mainly strikes younger people. However, if detected early and treated effectively, people frequently recover, and this kind of glaucoma seldom results in blindness. There is occasionally a chance for the pigment dispersion to regress over time, and there may even be a return to “normal” eye pressures in rare circumstances. Regular follow-up exams with your ophthalmologist are essential to the preservation of vision in all cases with glaucoma.

FAQ’s

Is there a cure for pigmentary glaucoma? 

A pigment dispersion glaucoma illustration: Treatment for patients with pigmentary glaucoma can be effective. Thankfully, many individuals can keep their good vision thanks to innovative therapies. 

Is pigment dispersion syndrome a dangerous condition? 

Oftentimes, pigment dispersion syndrome does not manifest any symptoms or has a wide range of long-term negative effects. However, pigmentary glaucoma, a kind of secondary glaucoma, might be made more likely by it. One of the main reasons for blindness worldwide is glaucoma, which is brought on by damage to the optic nerve. 

What symptoms might indicate pigment dispersion syndrome? 

Signs: Defects in the iris’ radial periphery transillumination. A Krukenberg spindle is a pigment deposition on the posterior surface of the cornea that is vertically oriented. a dark brown or black streak along the length of the trabecular meshwork.