What Is Pigmentary Glaucoma?

Pigmented glaucoma (PG) is a type of glaucoma caused by the loss of pigment particles on the posterior surface of the iris, which is deposited on the trabecular meshwork and hindered by the outflow of aqueous humor.

Basic Information

English name: pigmentary glaucoma
Visiting department: Ophthalmology
Multiple groups: 25 to 40 year old men

Common causes: Related to heredity, myopia, and deep anterior chamber
Common symptoms: Corneal vertical spindle pigment particle deposition, trabecular meshwork uniform pigment particle deposition, etc.

Causes of pigmented glaucoma

Most patients are sporadic and are related to myopia and deep anterior chamber. Patients are prone to reverse pupil block and depigmentation in the above dissection. Some patients show a certain familial nature. Studies have shown that the genes are located on the long arm of chromosome 7.

Clinical manifestations of pigmented glaucoma

The main clinical manifestations are a group of syndromes where pigment particles are deposited in the anterior segment of the eye, including: corneal vertical spindle-shaped pigment particle deposition (Krukenberg pigment shuttle), uniform and consistent pigment particle deposition on the trabecular meshwork, pre-iris indication, and lens Suspended ligament pigment particle deposition; and the phenomenon of light transmission after the absence of pigment particles on the surface of the iris (iris transillumination defect). In people of color, the phenomenon of iris transillumination is extremely rare.

Pigmented glaucoma

Slit lamp and gonioscopy are the most important clinical examinations and diagnostic methods. The following auxiliary examinations are helpful for the screening and diagnosis of patients.

1. Infrared TV camera

Infrared television camera is used to observe and count the iris transillumination defect site, and to make the data into data, which is helpful for the follow-up and follow-up of patients who are in the pigment dispersing activity period.

2. Tonometer

In patients with pigment dispersive syndrome (PDS) / pigmented glaucoma, ocular tracing and the measurement of aqueous humor outflow still have certain auxiliary diagnostic effects. According to the coefficient of aqueous humor, the development trend and outcome of the disease can be predicted, and the activity of pigment dispersal can also be understood. The development trend is predicted from the changes in the coefficient of aqueous humor, and patients with normal IOP and abnormal coefficient of humor often develop glaucoma. And those with smooth outflow of aqueous humor rarely develop into PG.

3. Ultrasound biological microscope

High-frequency, high-resolution anterior segment ultrasound biomicroscopy can provide a cross-sectional image of the iris morphology around the PDS / PG patient, and can determine the relationship between the iris and the anterior chamber and lens surface. Ultrasound biomicroscopy in vivo has confirmed that the frictional areas of the suspensory ligament of the iris that were previously only visible through postmortem dissection.

4.Angular microscopy with pigmented scale

Boys-Smith and others invented a corner mirror with pigment scales. Using this mirror, a unified index can be used to measure the degree of pigment deposition in the trabecular meshwork.

Diagnosis of pigmented glaucoma

It is mainly based on the signs and changes of intraocular pressure, glaucoma visual field, and optic disc with PDS; the transillumination test found that the mid-peripheral iris spoke-shaped light-transmitting area was most characteristic. Another slit lamp examination showed Krukenberg spindle pigmentation on the posterior surface of the cornea, deep anterior chamber, retrograde iris with pigmentation, and pigmentation on the posterior surface of the lens near the equator after dilation. Acornoscopy showed a wide angle and a densely pigmented zone in the trabecular meshwork. Those with retrograde iris and one of the other signs can be diagnosed as PDS; if accompanied by pathological high intraocular pressure, glaucoma visual field and optic disc changes, can be diagnosed as PG.

1. pigment loss of iris

There are no other iris depigmentation diseases similar to the iris wheel radial transillumination defect in PDS / PG. In patients with congenital glaucoma, transillumination defects are occasionally seen in the peripheral part of the iris near its attachment, but are not spoke-shaped. Patients with exfoliation syndrome occasionally have pigment spread, and the location of the transillumination defect is mostly at the edge of the pupil, or the entire iris appears as a scattered patch. Due to trauma or surgery, the posterior surface of the iris is damaged, causing irregular iris pigmentation. Patients with depigmentation of the posterior surface of the iris due to severe uveitis also show regional patchy loss, but not peripheral spoke-shaped defects. Occasionally a marble pattern-like transillumination defect may be seen in some normal eyes, but it is very different from the PDS / PG change

Uveitis

If there are small pigment particles floating in the aqueous humor, they will be mistaken for white blood cells, which will be misdiagnosed as uveitis. To make the right judgment, you must pay attention to the typical signs of PDS and lack other symptoms of uveitis, such as conjunctival hyperemia, KP, and post-iris adhesions. The loss of posterior iris surface pigment in patients with PDS, although phagocytic cells can advance into the iris matrix, does not trigger an inflammatory response. Herpes zoster uveal uveitis can cause fan-shaped iris atrophy, and herpes simplex kerat uveitis can cause extensive iris atrophy. Neither had a PDS-like iris transillumination defect.

3. Increased trabecular meshwork pigment

In addition to PDS / PG, abnormal pigmentation can also occur in the eyes of other syndromes. Pigment dispersal caused by exfoliation syndrome can cause trabecular meshwork to become noticeably darker. In many of these cases, the pigment is mixed with the exfoliating material of the capsule to form an irregular, hemp-like pigment band. A typical Krukenberg shuttle rarely appears in this disease. A typical exfoliation of the capsule helps the differential diagnosis.

Patients with peripheral iris or ciliary body cysts occasionally have moderate pigmentation on the trabecular meshwork, but do not have the typical Krukenberg shuttle. Diagnosis is by observing the transillumination defect peculiar to the peripheral iris PDS. To make a clear diagnosis, under the condition of mydriasis, the angle of the iris cyst should be seen with a gonioscopy. In both cases, no pigment was deposited on the rear surface around the lens.

4. Anterior and posterior melanoma

Iris, ciliary body, or posterior melanoma (if the vitreous anterior limiting membrane is ruptured) can be accompanied by pigment dissemination. Pigmented tumor cells or pigmented phagocytic cells can cause some blackening of the anterior and posterior chambers. But the typical symptoms of lack of PDS / PG: no Krukenberg shuttle and no transillumination defect. Easy to find primary tumor. The inflammation of the posterior surface of the iris may occasionally be released in a moderate amount of pigment, often clustering in the lower angle of the chamber, accompanied by the manifestation of inflammation.

5. Other

Implantation of the posterior chamber intraocular lens can sometimes cause PG. At this time, the abnormal position of the posterior chamber IOL and the iris can cause pigment release after long-term contact and friction.

6. Exfoliation syndrome

Patients with exfoliation syndrome have mechanical friction between the peripheral lens and the iris around the pupil, which is similar to pigmented glaucoma, with iris transillumination defects, and Krukenberg shuttle, trabecular pigmentation, and elevated intraocular pressure. However, the following situations are easy to identify:

(1) It is more common in the elderly over 60 years, and it is rare to be under 40 years of age;

(2) 50% of patients are unilateral, without gender, refractive error (myopia) tendency;

(3) Transillumination defects are common in the pupil edge and its surrounding iris, and rarely in the mid-peripheral iris. Trabecular meshwork pigmentation is not as dense as pigmented glaucoma (usually grade 2);

(4) The most distinguishing features are gray-white dandruff-like particles or flakes on the edge of the pupil, and gray pseudo-ablative substances on the anterior capsule of the surrounding lens. It has been reported that two diseases can coexist.

Pigmented glaucoma treatment

Medication can be used with low-concentration pilocarpine in the eye. By reducing the pupil, reducing the friction of the iris suspension ligament, reducing pigment shedding, at the same time promoting aqueous humor, removing pigment particles in the trabecular meshwork and reducing intraocular pressure. Laser iris punching can effectively reverse the reverse pupil block and iris retrograde, and block the release of pigment particles caused by the friction between the iris and the lens ligament. If the intraocular pressure cannot be controlled after drug or laser treatment, trabeculectomy can be considered.