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27.What is the technique of bleb needling?

Needling can be done in the operating room or at the slit lamp. A sterile technique is required, including the use of topical diluted Betadine. Subconjunctival injection of

1% nonpreserved lidocaine is used. A 27-gauge needle is introduced into the subconjunctival space 8–10 mm away from the scleral flap, is directed toward the bleb, and if possible, under the scleral flap to ensure an outpouring of aqueous. Needling could be supplemented with 5-FU. Some surgeons use 0.1 mL of 0.4mg/mL MMC diluted with 0.1 mL of 1% nonpreserved lidocaine injected on a 30-gauge needle under the conjunctiva and Tenon’s capsule 5–10 minutes prior to needling the bleb. The MMC/lidocaine mixture should be completely dissipated prior to the procedure. The point of needle entry into the conjunctiva is cauterized with a disposable hand-held unit. Post-operative topical antibiotics and steroids are used.

Shetty RK, Warluft L, Moster MR. Slit-lamp needle revision of failed filtering blebs using high-dose mitomycin-C. J Glaucoma 14:52–56, 2005.

28.What is the differential diagnosis for a flat anterior chamber?

The most common cause of a flat chamber after glaucoma surgery is excessive filtration. Other possibilities include serous choroidal detachment, hemorrhagic choroidal detachment, pupillary block, and malignant glaucoma (Table 19-1). With excessive filtration and

serous choroidal detachment, the IOP is low. With a hemorrhagic choroidal detachment, the IOP may be low, normal, or high and usually is associated with pain. With both pupillary block and malignant glaucoma, the IOP is typically elevated, and the cornea often edematous.

TABLE 19-1. P R E V E N T I O N O F M A L I G N A N T G L A U C O M A ( A Q U E O U S

M I S D I R E C T I O N )

1.Detect high-risk cases (angle closure glaucoma, small, hyperopic eyes).

2.Minimize intraoperative shallowing of anterior chamber.

3.Perform a large peripheral iridectomy.

4.Avoid overfiltration.

5.Cautious suture lysis.

6.Use cycloplegics. Taper cycloplegics slowly.

29.How urgent is the management of a flat anterior chamber?

Grade I (contact between the peripheral iris and the cornea) commonly occurs in the presence of excessive filtration. Treatment includes use of cycloplegics and mydriatics and careful observation. Improvement is usually spontaneous. A grade I may worsen and become a grade II (contact between the peripheral iris and cornea up to the pupil). This progression may be a poor prognostic sign, especially if the pressure is falling and the bleb is flattening. Grade II may recover spontaneously or progress to grade III (contact between the corneal endothelium and lens). Grade III is a surgical emergency and must be corrected promptly or the cornea will decompensate.

30.What are the indications to drain a choroidal detachment?

Whenever the pressure consistently falls, the bleb flattens, and the chamber shallows despite reformation with viscoelastic material, drainage of the associated choroidal detachment is indicated. Appositional ‘‘kissing’’ choroidal effusions that do not improve

198 TRABECULECTOMY SURGERY

after a few days should also be drained (Fig. 19-12). A full-thickness scleral incision is made in one of the inferior quadrants to reach the suprachoroidal space. Reformation of the anterior chamber is done simultaneously with BSS through the paracentesis tract.

Figure 19-12. Ultrasound of kissing choroidals following a filtering procedure in an eye with chronic angle closure.

1.What is a hyphema?

A hyphema is blood in the anterior chamber. The appearance of a hyphema may range from microscopic, seen only at the slit lamp as erythrocytes circulating in the aqueous, to a total hyphema that fills the entire anterior chamber.

2.List the causes of a hyphema.

There are three major causes: trauma to the globe, intraocular surgery, or spontaneous anterior segment hemorrhage in association with ocular or systemic conditions, such as neovascularization of the iris or anterior chamber angle, intraocular tumors, or clotting disorders (Table 20-1).

3.What is the most common cause of a traumatic hyphema?

Blunt anterior segment trauma.

4.Describe the pathophysiology of a traumatic hyphema.

Blunt ocular trauma results in ocular indentation, which causes a sudden expansion of ocular tissues and an immediate rise in the intraocular pressure. The sudden forceful displacement of the cornea and limbus posteriorly and peripherally may result in splitting or tearing of these tissues. As the tissues tear, blood vessels in the vicinity may rupture, resulting in a hyphema.

5.List the anterior segment structures that may split or tear in response to blunt ocular injury.

&Central iris: Sphincter tear

&Peripheral iris: Iridodialysis

&Anterior ciliary body: Angle recession

&Separation of ciliary body from the scleral spur: Cyclodialysis

&Trabecular meshwork: Trabecular meshwork tear

&Zonules/lens: Zonular tears with possible lens subluxation

&Separation of the retina from the ora serrata: Retinal dialysis

6.When a patient presents with a hyphema due to blunt ocular trauma, which anterior segment structure is the most likely source of the hemorrhage?

Hyphema as a result of blunt ocular trauma most commonly occurs as a result of angle recession, a tear in the anterior face of the ciliary body between the longitudinal and circular ciliary body muscles. Rupture of the blood vessels in the vicinity of the tear results in a hyphema. The most frequently ruptured blood vessels include the major arterial circle of the iris, arterial branches to the ciliary body, and the recurrent choroidal arteries and vein crossing between the ciliary body and episcleral venus plexus.

7.What ocular injuries may be associated with a traumatic hyphema?

&Ocular wall: Ruptured globe at the cornea, limbus, and/or sclera

&Cornea/conjunctiva: Epithelial abrasion, laceration, subconjunctival hemorrhage

&Iris: Sphincter tears, iris dialysis, mydriasis (long-term)

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200 TRAUMATIC GLAUCOMA AND HYPHEMA

TABLE 20-1. H Y P H E M A C L A S S I F I C A T I O N B Y E T I O L O G Y

I.Trauma

A.Blunt—rupture of iris or ciliary body blood vessels

B.Penetrating—direct severing of blood vessels

II. Intraocular surgery

A.Intraoperative bleeding

1.Ciliary body or iris injury—most common when performing cyclodialysis, peripheral iridectomy, guarded filtration procedure, and cataract extraction

2.Laser peripheral iridectomy—bleeding is more common with the YAG laser than with the argon laser

3.Argon laser trabeculoplasty—rarely

4.Selective laser trabeculoplasty—extremely rare

5.Cyclodestructive procedures—common, depending on the mechanism of elevated intraocular pressure (e.g., neovascular glaucoma)

B.Early postoperative bleeding

1.Dilation of a traumatized uveal vessel that was previously in spasm

2.Conjunctival bleeding that enters the anterior chamber through a corneoscleral wound or a sclerostomy

C.Late postoperative bleeding

1.Disruption of new vessels growing across the corneoscleral wound

2.Reopening of a uveal wound

3.Chronic iris erosion from an intraocular lens causing fibrovascular tissue growth

III. Spontaneous

A.Neovascularization of the iris

carotid occlusive disease

B. Intraocular tumors

C.Iris microhemangiomas—may be associated with diabetes mellitus and myotonic dystrophy

D.Clotting factors

IV. Indirect: spillover from vitreous hemorrhage

Adapted from Gottsch JD: Hyphema: Diagnosis and management. Retina 10:S65–S71, 1990.