Pigment Liberation Test in Open‐angle Glaucoma

Abstract

In 1921 Koelner described a patient with simple glaucoma, whose intraocular pressure rose 10 mm Hg on dilatation of the pupil. This patient had abundant pigment on the posterior surface of the cornea and the anterior surface of the iris. In 12 other patients with simple glaucoma mydriasis provoked by atropine, homatropine, or scopolamine involved no rise in pressure. Vogt (1925), among 12 patients with pseudo-exfoliation of the anterior lens capsule, found two in whom dilatation of the pupil released an excessive liberation of pigment floating in the aqueous humour. These patients suffered from glaucoma. No mention is made of the tension in relation to the appearance of pigment granules.Various workers, e. g. Bard (1934) and Pillat (1934) have since reported on such floaters in the aqueous humour following mydriasis. Pillat, using a stop watch, measured the velocity of movement of the pigment granules in the aqueous humour of patients with glaucoma and pseudo-exfoliation. A distance of 1 cm was covered in 75 seconds.We now know that even in normals mydriasis is often followed by presence of floaters in the aqueous humour. This may be of importance in the differential diagnosis from iritis. The mydriasis-induced floaters differ, however, completely in kind from those occurring in genuine iritis. The former consist in the main of fine, brownish, sometimes glossy, bronze-coloured pigment granules, whercas the latter are larger and greyish. These consist predominantly of mononuclear cells.In patients with open-angIe glaucoma, with or without pseudo-exfolation, such a mydriasis-induced pigment liberation may be excessive and sometimes be accompanied by an acute, transistory rise in pressure. This is a factor which seems to have attracted little attention, being mentioned in none of a series of reports on the influence of mydriatics on glaucomatous eyes and normal eyes. Rentz ( 1924) described the effect of subconjunctival adrenalin injection 586

The Cyclopentolate Provocative Test in Suspected or Untreated Open‐angle Glaucoma

“…3.1 mmHg) in new, previously untreated open-angle glaucoma eyes was smaller in this material than the values reported by Kristensen (1968) and Makabe (1970a). The mean IOP elevation in their T h e mean change (+0.4 i -2.5 mmHg) in IOP in the eyes with suspected glaucoma concurs with the values reported earlier for healthy eyes tested with parasympatholytics (Table 11).…”

Changes in intraocular pressure after pharmacologic pupil dilation

“…Kristensen showed that 48% of eyes with open angle glaucoma showed a rise in pressure of 8 mmHg or more after dilation, and all elevations were associated with marked pigment elevation [19]. Valle demonstrated IOP elevations of up to 20 mmHg after dilation with 1% cyclopentolate, all of which were accompanied by pigment liberation [20].…”

The amount of intraocular pressure rise during pharmacological pupillary dilatation is an indicator of the likelihood of future progression of glaucoma

“…Kristensen showed that 48% of eyes with open-angle glaucoma had an IOP rise of 8 mmHg or more when dilated with 10% phenylephrine 8. Harris demonstrated that approximately 23% of patients with primary open-angle glaucoma had a significant rise in IOP following administration of cycloplegics 9.…”

“…Studies have suggested that the rise in IOP reaches its maximum between 45 and 120 min after cyclopentolate drops are administered, and lasts for 4–6 h if left untreated 9 11. The exact mechanism by which this increase in pressure takes place is not known, though it might result from pigment liberation into the anterior chamber and subsequent obstruction of the trabecular meshwork 8. Alternatively, it might result from decreased pull on the trabecular meshwork due to ciliary muscle paralysis, leading to a drop in aqueous outflow 11…”