REFERENCES

1. Weiss JN, Bynoe LA. Injection of tissue plasminogen activatorinto a branch retinal vein in eyes with central retinal veinocclusion. Ophthalmology 2001;108:2249–2257.

2. The Central Vein Occlusion Study Group. Evaluation of gridpattern photocoagulation for macular edema in central veinocclusion: The Central Vein Occlusion Study Group Mreport. Ophthalmology 1995;102:1425–1433.

3. Fong ACO, Schatz H, McDonald HR, et al. Central retinalvein occlusion in young adults (papillophlebitis). Retina1991;11:3–11.

4. Weiss JN. Treatment of central retinal vein occlusion byinjection of tissue plasminogen activator into a retinal vein.Am J Ophthalmol 1998;126:142–144.

5. Weiss JN. Retinal surgery for treatment of central retinal veinocclusion. Ophthalmic Surg Lasers 2000;31:162–165.

Iris Color and Intraocular Pressure:The Blue Mountains Eye StudyRobert Mitchell, MBBS,Elena Rochtchina, BSc, MAppl Stat,Anne Lee, MBBS, Jie Jin Wang, MMed, PhD,and Paul Mitchell, MD, PhD, FRANZCO

PURPOSE: To assess the relationship between iris colorand intraocular pressure (IOP).DESIGN: Population-based, cross-sectional study.METHODS: The Blue Mountains Eye Study examined3,654 largely Caucasian participants, aged 49 to 97years, from 1992 to 1994. Information was collectedabout glaucoma risk factors, and Goldmann applanationIOP measurements were taken. Iris color was assessed bycomparing the undilated appearance of each eye withthree standard photographs. Participants who had previ-ous cataract or glaucoma surgery and those using glau-coma medications were excluded.RESULTS: Mean IOP measurements increased with in-creasing grades of iris pigmentation. After simultaneousadjustment for variables associated with IOP, mean mea-surements were 15.92 mm Hg for blue iris color, 16.04 mmHg for hazel or green, 16.11 mm Hg for tan-brown, and16.49 mm Hg for dark brown (P for trend � .001).CONCLUSIONS: This study demonstrates a modest but sta-tistically significant association between increasing iris colorand IOP. (Am J Ophthalmol 2003;135:384–386.© 2003 by Elsevier Science Inc. All rights reserved.)

Accepted for publication Sept 27, 2002.From the Christchurch School of Medicine (R.M.), University of

Otago, Christchurch, New Zealand; and Centre for Vision Research(E.R., J.J.W., P.M.), Department of Ophthalmology, University of Syd-ney, Westmead Hospital, Westmead, Australia.

Inquiries to Paul Mitchell, MD, PhD, FRANZCO, Centre for VisionResearch, Department of Ophthalmology, University of Sydney, Hawkes-bury Rd, Westmead NSW, Australia, 2145; fax: (�61) 2-9845-6117;e-mail: paulmi@westgate.wh.usyd.edu.au; Web site: www.cvr.org.au

FIGURE 2. (Top) Preoperative fundus photograph of case 2showing marked intraretinal hemorrhage and edema in allquadrants. (Middle) Fundus photograph 3 days following reti-nal endovascular surgery and intravitreal triamcinolone ace-tonide injection, showing decreasing retinal hemorrhages andedema. (Bottom) Fundus photograph at 8 weeks, showingfurther resolution of retinal hemorrhages and edema.

AMERICAN JOURNAL OF OPHTHALMOLOGY384 MARCH 2003

INTRAOCULAR PRESSURE (IOP) IS CLINICALLY RELEVANT

as a major risk factor for open-angle glaucoma.1 We knowof three studies that have reported a small, statisticallysignificant association between iris color and IOP.2–4

These studies showed a general trend for eyes with brownirides to have higher IOP than those with blue irides. Twoof these studies commented that this association tends tobe seen in older age groups.2,3

Data from the Health and Nutrition Examination Sur-vey of 1971–19722 found a decreasing proportion of IOPreadings of 20 mm Hg or greater in persons of white racewith decreasing iris pigmentation. The authors of the studyconcluded that iris pigmentation may therefore be animportant risk factor for known or suspected glaucoma.Data from the Wisconsin Epidemiologic Study of DiabeticRetinopathy,3 however, found no association betweenglaucoma and darker eye color. In this study, the presenceof glaucoma was based on history alone, suggesting thepossibility of selection bias.3

The Blue Mountains Eye Study provided an opportunityto further assess the association between iris color and IOP.This study involved 3,654 persons aged 49 to 97 years(82.4% of eligible residents) living in two postal-code areasof the Blue Mountains region, west of Sydney, Australia.The study methods have been described previously.5

Participants provided detailed past medical and fam-ily history. Intraocular pressure was measured usingapplanation tonometry with a calibrated Goldmanntonometer. Iris color was assessed as blue, hazel or green,tan-brown, or dark brown by comparing the undilatedappearance of each eye with three standard photo-graphs, as used in the Beaver Dam Eye Study andprovided by Dr. Ronald Klein, University of Wiscon-sin—Madison. Participants were excluded if they hadprevious cataract or glaucoma surgery, signs of pigmen-tary glaucoma or pigment dispersion, were currently

using glaucoma medications, or had incomplete risk-factor data. The final analysis included 3,251 partici-pants. Statistical analyses were performed usingStatistical Analysis System (SAS, Cary, North Caro-lina, USA). A generalized linear model analysis wasused to assess multivariate-adjusted mean IOP levels.

Of the 3,251 participants included, 1,618 (50%) hadblue eyes, 907 (28%) had hazel or green eyes, 401 (12%)had tan-brown eyes, and 325 (10%) had dark brown eyes.Table 1 shows that the mean IOP increased with increas-ing iris pigmentation, after adjusting for age and gender (Pfor trend � .0018). After simultaneous adjustment forvariables found associated with intraocular pressure (age,gender, systolic blood pressure, family history of glaucoma,myopia, diabetes, current smoking, and pseudoexfolia-tion), the trend was unchanged. Multivariate-adjustedmean IOP levels were 15.92 mm Hg for blue eyes, 16.04mm Hg for hazel or green eyes, 16.11 mm Hg for tan-browneyes, and 16.49 mm Hg for dark brown eyes. In amultiple-regression model of variables associated with IOP,the association with iris color remained statistically signif-icant, as shown in Table 2.

The underlying pathogenesis of the relationship be-tween iris color and IOP is not known. A number ofstudies have shown higher levels of elevated IOP andglaucoma in subjects of black race,2 but our communityis largely Caucasian (white). Although we excludedcases with definite pigment dispersion syndrome, subtlecases could have been missed.

In summary, this population-based study provides fur-ther evidence of a modest, statistically significant associa-tion between iris color and IOP. Persons with dark irideshad slightly higher intraocular pressure levels than thosewith lighter colored irides. Iris color thus appears to be oneof the ocular determinants of IOP.

REFERENCES

1. Leske MC. The epidemiology of open-angle glaucoma: areview. Am J Epidemiol 1983;118:166–191.

TABLE 2. Multiple Regression Model of Association WithIntraocular Pressure

Variable �-Coefficient P Value

Age �0.002 .66

Sex 0.164 .09

Systolic blood pressure 0.028 .0001

Family history of glaucoma* 0.883 .0001

Myopia* 0.340 .0009

Diabetes* 0.514 .005

Current smoking* 0.262 .04

Pseudoexfoliation* 0.914 .007

Iris color 0.146 .001

*Categorical variables—yes/no.

TABLE 1. Mean Intraocular Pressure (mm Hg) by IrisColor, Adjusted for Age and Sex, and

Multivariate-Adjusted*

Level of Adjustment Iris Color n Mean � SE P for Trend

Age- and blue 1,618 15.92 � 0.07

sex-adjusted hazel/green 907 16.05 � 0.09

tan/brown 401 16.07 � 0.13

dark brown 325 16.47 � 0.15 .002

Multivariate- blue 1,618 15.92 � 0.07

adjusted hazel/green 907 16.04 � 0.09

tan/brown 401 16.11 � 0.13

dark brown 325 16.49 � 0.15 .001

SE � standard error.

*Adjusted for age, sex, systolic blood pressure, family history

of glaucoma, myopia, diabetes, current smoking and

pseudoexfoliation.

BRIEF REPORTSVOL. 135, NO. 3 385

2. Hiller R, Sperduto RD, Krueger DE. Race, iris pigmentation,and intraocular pressure. Am J Epidemiol 1982;115:674–683.

3. Moss SE, Klein R, Meuer MB, Klein BE. The association of iriscolor with eye disease in diabetes. Ophthalmology 1987;94:1226–1231.

4. Weih LM, Mukesh BN, McCarty CA, Taylor HR. Associationof demographic, familial, medical, and ocular factors withintraocular pressure. Arch Ophthalmol 2001;119:875–880.

5. Mitchell P, Smith W, Attebo K, Healey PR. Prevalence ofopen-angle glaucoma in Australia. The Blue Mountains EyeStudy. Ophthalmology 1996;103:1661–1669.

Surgery for Subfoveal ChoroidalNeovascularization in ToxoplasmicRetinochoroiditisAlfredo Adan, MD, Carlos Mateo, MD, andCharlotte Wolley-Dod, MD

PURPOSE: To report a case of subfoveal choroidal neovas-cularization in a patient with toxoplasmic retinochoroid-itis who underwent surgical excision.DESIGN: Interventional case report.METHODS: A 36-year-old woman with toxoplasmic reti-nochoroiditis presented with sudden dimness of visionand metamorphopsia in the left eye. The patient wasexamined with ophthalmoscopy and fluorescein angiog-raphy.RESULTS: Fundus examination and fluorescein angiogra-phy of the left eye revealed a subfoveal choroidal neo-vascularization. Pars plana vitrectomy with submacularsurgery was performed, with a postoperative improve-ment of visual acuity and resolution of the distortion.CONCLUSIONS: This case report describes a case of sub-foveal choroidal neovascularization associated with tox-oplasmic retinochoroiditis that responded remarkablywell to vitrectomy surgery. (Am J Ophthalmol 2003;135:386–387. © 2003 by Elsevier Science Inc. Allrights reserved.)

OCULAR TOXOPLASMOSIS IS TYPICALLY CHARACTER-

ized by focal necrotizing retinitis next to old chori-oretinal scars. Foveal involvement accounts for themajority of cases of sudden visual loss associated with thisinfection. However, other causes of central visual loss thatshould form part of the differential diagnosis includesubfoveal choroidal neovascularization adjacent to areas ofretinochoroiditis.1,2 The development of this complication

usually appears late and is generally associated with cho-rioretinal scars.

We describe below the clinical course and treatment ofa case of toxoplasma retinochoroiditis with secondarychoroidal neovascularization treated by pars plana vitrec-tomy and surgical removal of a choroidal membrane withsubsequent improvement of visual acuity and visual distor-tion.

A 36-year-old woman was referred with visual loss in theleft eye with metamorphopsia. She had a history oftoxoplasma retinochoroiditis that had been treated 2 yearspreviously with oral sulphadiazine and pyrimethamine fora period of 3 weeks. On examination the visual acuity was20/20 in the right eye and 20/200 in the left eye. Theantitoxoplasma antibody titer was positive at 1:48. Exam-

Accepted for publication Sept 18, 2002.From the Department of Ophthalmology (A.A., C.W.-D.), Hospital de

Santa Creu i Sant Pau, Universidad Autonoma de Barcelona, and theInstituto de Microcirugıa Ocular (A.A., C.M.), Universidad Autonomade Barcelona, Barcelona, Spain.

Inquiries to Alfredo Adan, MD, Department of Ophtalmology, Hos-pital de Santa Creu i Sant Pau, Avenida Sant Antoni M. Claret,167,08025 Barcelona, Spain; fax: (�34)93-291-9466; e-mail: 7705@hsp.sant-pau.es

FIGURE 1. (Top) Macula of left eye. Typical toxoplasma scarinferotemporal to the macula associated with a subfoveal neo-vascular membrane. (Bottom) Preoperative fluorescein angio-gram showing subfoveal choroidal neovascular membrane.

AMERICAN JOURNAL OF OPHTHALMOLOGY386 MARCH 2003