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Clinicopathologic Reports, Case Reports, and Small Case Series
August 2004

Episodic Elevations in Intraocular Pressure Associated With Blood inthe Schlemm Canal

Arch Ophthalmol. 2004;122(8):1230-1232. doi:10.1001/archopht.122.8.1230

Elevated intraocular pressure (IOP) associated with blood in the Schlemmcanal may be associated with many different conditions.1-3 Toour knowledge, we describe a previously unreported case of a patient withrecurrent, intermittent spikes in IOP associated with episodic and transientblood in the Schlemm canal. Whenever the patient was examined because of elevatedIOP in one or both eyes, gonioscopy disclosed the presence of blood in varyingquadrants of the Schlemm canal in the affected eye(s). Whenever IOP was normalized,with or without medical therapy, the blood was no longer visualized.

Report of a Case

A 38-year-old woman of Latin American descent sought medical care becauseof right ocular pain, redness, and decreased visual acuity of approximately12 hours' duration. The pain was not relieved by ibuprofen. The patient reporteda history of similar ocular episodes that had occurred intermittently duringthe preceding 2 years. Her medical history was significant for systemic hypertensionand left elbow surgery; her blood pressure was 160/90 mm Hg at the time ofexamination. Therewas no significant ocular, family, or social history.

On initial examination, visual acuities were 20/40 OD and 20/25 OS,with a mid-dilated, minimally reactive pupil in the left eye. We found noproptosis, orbital bruits, or pulsating exophthalmos. The right conjunctivalregion had a mild red appearance, and mild corneal edema or haze was notedin the right eye. There was no apparent dilation of the episcleral veins.The left anterior segment appeared normal. Goldmann applanation tonometrymeasurements were 55 mm Hg OD and 17 mm Hg OS. In the right eye, gonioscopyshowed open angles with blood in the Schlemm canal inferiorly, temporally,and superiorly (Figure 1). Gonioscopicfindings of the left angle structures were unremarkable. Dilated funduscopicexamination of the right eye showed mild vascular tortuosity without leakageon fluorescein angiography. Ophthalmodynomometry measurements were 70 mm HgOD and 60 mm Hg OS (both within normal limits). The elevated IOP was initiallytreated with an intensive course of topical medications and oral agents (eg,acetazolamide and glycerin). Once the IOP was normalized, the patient wasprescribed an antiglaucoma regimen of timolol maleate, latanoprost, and dorzolamidehydrochloride.

Gonioscopic view of the angles of the right eye. Blood can be seenin the Schlemm canal.

Gonioscopic view of the angles of the right eye. Blood can be seenin the Schlemm canal.

During the next 5 months, the patient experienced recurrent, intermittentepisodes of increased IOP in either or both eyes. These IOP spikes were alwaysassociated with the gonioscopic presence of blood in varying quadrants ofthe Schlemm canal. Whenever IOP was normalized in the affected eye(s), withor without medical therapy, the blood was no longer visualized. The patientalso experienced 2 mild episodes of white-colored cells and flare noted inthe anterior chamber, both resolving within a few days. At any of the visits,no signs of hyphema, either on slitlamp or gonioscopic examination, were noted.

A computed tomographic scan of the head (with contrast) showed thatboth superior ophthalmic veins were normal; no mass effect was noted. An openmagnetic resonance imaging scan (with gadolinium enhancement) was also readas within normal limits; the cavernous sinus and ophthalmic veins were unremarkable.Automated visual fields (created with the 24-2 SITA program; Humphrey Instruments,Inc, Dublin, Calif) were normal in both eyes. Measurement of the episcleralvenous pressure was within normal limits in both eyes. Doppler imaging ofthe jugular, subclavian, and upper extremity venous system showed normal valuesfor compression and velocity. Extensive laboratory evaluation results (includinga full hypercoagulable workup), as well as fluorescent treponemal antibodyabsorption test results, erythrocyte sedimentation rate, and beta human chorionicgonadotropin, rapid plasma reagin, antinuclear antibody, serum angiotensin-convertingenzyme, and Lyme antibody titers, were all within normal limits. The chestx-ray film was also within normal limits. Of note, the patient was found tohave a positive sickle cell trait on hemoglobin electrophoresis (HbAS trait;such individuals have 1 copy of the normal hemoglobin A gene and 1 copy ofthe hemoglobin S gene).


In our patient, the differential diagnosis included increased episcleralvenous pressure due to Sturge-Weber syndrome, dural cavernous sinus fistula,carotid-cavernous sinus fistula, superior vena cava syndrome, orbital arteriovenousfistula, jugular vein obstruction, thyroid ophthalmopathy, and idiopathicfamilial entities.3 Other causes of bloodin the Schlemm canal include artifact due to the compression of episcleralveins with the Goldmann or Allen-Thorpe goniolens, ocular hypotony (followinginjury, inflammation, or cyclodialysis), and pathologic deep arterial anastomosisfrom a deep limbal artery to the Schlemm canal.1,2 Duringour extensive diagnostic evaluation (including normal values on episcleralvenous pressure testing), these diagnoses were eventually excluded.

A systematic review of the literature demonstrated one previous casereport4 of a patient with HbAS trait whowas first seen because of a single episode of elevated IOP in one eye associatedwith blood in the Schlemm canal. However, our patient had multiple intermittentepisodes of elevated IOP associated with transient episodes of blood in theSchlemm canal, which appeared in either eye. Another recent case report5 described a patient with a 3-year history of uveitis-glaucoma-hyphemasyndrome who was diagnosed as having HbAS trait on the basis of cytopathologicexamination findings of the submitted aqueous fluid during posterior-chamberintraocular-lens explantation and anterior-chamber washout.

While patients with sickle cell disease (either hemoglobin SS [HbSS][individuals having 2 copies of the hemoglobin S gene] or HbSC [individualshaving 1 copy of the hemoglobin S gene and 1 copy of the hemoglobin C gene])are well known to have systemic and ocular vaso-occlusive episodes, littleis known about the extent of increased coagulation activity in individualswith HbAS trait.6 Although HbAS trait disordersare usually asymptomatic in nature, we theorize that in our patient, the HbAStrait caused localized sickling of the red blood cells (with subsequent sludging)in the Schlemm canal. In support of this theory, a recent study6 reportsthat individuals with HbAS trait have increased coagulation activity (althoughit is lower than in patients with HbSC or HbSS disease). Moreover, Goldberg7 has reported that patients with sickle cell hemoglobinopathies(including AS) have a higher percentage of sickled erythrocytes in their anteriorchambers than in their circulating venous blood. Injection of sickle cellerythrocytes (AS, SS, SC, and Sthal [consisting of 1 copy of the hemoglobinS gene and 1 copy of the hemoglobin β-thalassemia gene]) into the anteriorchambers of living human, monkey, or guinea pig eyes results in sickling ofthe red blood cells with resultant IOP elevation.8 Furthermore,a vicious cycle of hypoxia and acidosis are known to contribute to increasedsickling of the erythrocytes.9 In our patient,we suggest that intermittent episodes of sickled red blood cells in the trabecularmeshwork (as a result of the HbAS trait) contributed to her transient elevationsin IOP.

The authors have no relevant financial interest in this article.

This study was supported in part by the Homer McK. Rees Scholar Award,New York, NY (Dr Tsai); the Eye Surgery Fund (Dr Tsai), New York; and unrestricteddepartmental grants from Research to Prevent Blindness, Inc, New York.

This study was presented in part at the Annual Meeting of the Associationfor Research in Vision and Ophthalmology; May 8, 2002; Fort Lauderdale, Fla.

Correspondence: Dr Tsai, Harkness Eye Institute, Columbia UniversityCollege of Physicians and Surgeons, 635 W 165th St, New York, NY 10032 (jct2002@columbia.edu).

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