Objectives. Little information exists regarding the causes of visual impairment and the most common eye problems in American Indians/Alaska Natives.

Methods. We randomly sampled American Indians/Alaska Natives older than 40 years from 3 tribes within the Northwest region.

Results. We found a higher prevalence of visual impairment and normal-tension glaucoma, as well as a lower prevalence of ocular hypertension, in American Indians/Alaska Natives compared with previous results in other racial/ethnic groups.

Conclusions. American Indians/Alaska Natives have a need for vision correction. Future interventions in American Indians/Alaska Natives should include providing spectacles for refractive error, detecting glaucoma, and preventing visual impairment from age-related maculopathy and cataracts.

Investigators need prevalence information to guide preventive health measures. Epidemiological studies have documented the prevalence and cause of visual impairment in non-Hispanic Whites, Hispanics, and Blacks in the United States.1–4 The Baltimore Eye Study indicated that undercorrected refractive error, cataracts, macular degeneration, and glaucoma were the most common causes of visual impairment and blindness in an urban population of Whites and Blacks.1,2 Proyecto VER (Project Vision, Evaluation, Research), a study examining the prevalence of diabetic retinopathy, cataracts, age-related macular degeneration, glaucoma, and other causes of visual loss in Mexican Americans, reported cataracts, macular degeneration, diabetic retinopathy, and glaucoma as the most common causes of visual impairment in Hispanics in southern Arizona.3 Macular degeneration was the most common cause of visual impairment in the Beaver Dam Study.4 The Los Angeles Latino Eye Study determined the risk factors for visual impairment in Latinos in urban Los Angeles County.5

Similar information regarding American Indian/Alaska Native (AIAN) populations does not exist. Most studies of AIAN populations have been chart reviews or convenience sample studies.6–8 These types of study designs do not reliably estimate the prevalence and causes of blindness because the selection criteria do not include randomization for all eligible participants of the population. Our purpose is to outline the common causes of visual impairment and the most common eye problems in a random sample of Northwest American Indians/Alaska Natives.

Selection Criteria

We randomly selected 3 tribes from the Northwest region of the United States (Oregon, Washington, and Idaho) for inclusion in the study. We assigned each tribe a computer-generated random number and invited the 3 tribes with the lowest numbers to participate. To be eligible, tribes needed to have at least 400 enrolled members aged 40 years or older. We used the tribal enrollment database to perform an age-stratified, random sample of these members. We excluded candidates who had died, were seriously ill, or had dementia (which prevents subjective testing such as visual acuity and visual field testing).

Each selected individual was invited to participate by phone and by mail. A tribal coordinator, a volunteer, or an ophthalmic technician interviewed and performed a baseline examination of all individuals. The interview determined AIAN heritage, ocular and medical history, family history, risk factors for eye disease with a modified Behavioral Risk Factor Surveillance Survey,9 and the effect of eye disease on quality of life with the National Eye Institute Visual Function Questionnaire (NEI-VFQ-25).10

Baseline Examination

The baseline examination included height; weight; blood pressure (taken after the participant had been sitting still for 5 minutes)11; automated refraction; keratometry; presenting and best-corrected near vision; Early Treatment Diabetic Retinopathy Study distance visual acuity on presentation and with best correction; intraocular pressure with Tono-Pen XL (Medtronic Solan, Jacksonville, Fla); random fingerstick blood glucose level and glycosylated hemoglobin; anterior chamber assessment by limbal chamber depth12,13; visual field testing with frequency-doubling technology (FDT) perimetry, program C-20-5; confocal scanning laser ophthalmoscopy; and nonmydriatic digital imaging of the lens, optic disc, and fundus.

Ophthalmologic Follow-Up Examination

The baseline examination contained several criteria for referral to a follow-up examination to allow the highest sensitivity (Table 1).12–15 An ophthalmologist performed this follow-up examination in all participants with abnormal findings and a subset of participants with normal findings to determine the accuracy of the baseline examination. The “normal” patients were selected with a random-number generator. The ophthalmologist used a data entry sheet separate from that used in the baseline examination to mask the results from the baseline examination and to reduce workup bias and review bias. The follow-up examination included biomicroscopy of the anterior segment, gonioscopy, Lens Opacity Classification System III grading of the lens,16 standard automated achromatic perimetry (24-2 Swedish interactive threshold algorithm standard, Humphrey Field Analyzer II, Carl Zeiss Meditech, Dublin, Calif), dilated fundus evaluation, and photographs of the optic disc and macula.

The ophthalmologist used standard criteria to determine the prevalence of eye disorders. Table 2 summarizes the case definitions for the eye diseases.17–23 The ophthalmologist determined the primary cause of the decreased visual acuity. When multiple abnormalities were present, the ophthalmologist ranked the diseases most likely to cause decreased visual acuity. A separate ophthalmologist independently confirmed any abnormality found during the follow-up examination by reviewing the patient history, testing results, and photographs of the optic disc and macula.

An abnormal standard achromatic automated perimetry result was defined as a pattern standard deviation outside 95% of age-specific norms; a glaucoma hemifield test result outside 99.5% of age-specific norms (outside normal limits on Statpac2 [Carl Zeiss Meditech, Dublin, Calif); or a mean deviation outside the 95% limits without generalized reduction in sensitivity.

Statistical Analysis

We compared the sample population demographic data with the demographic data contained within each tribe’s tribal enrollment database.

Our analysis required statistical weighting to accurately determine the prevalence of eye diseases, because not all persons with a normal baseline examination result were selected for the follow-up examination and not all persons with an abnormal baseline examination result completed a follow-up examination. The weighting was determined by dividing the total number of normal baseline examination results by the number of participants with normal baseline results who completed the follow-up examination (88/12 = 7.333) and by dividing the total number of abnormal baseline results by the number of participants with abnormal results who completed the follow-up examination (199/157 = 1.267). One participant had a home examination without a baseline examination; the result was not weighted.

We recruited a total of 288 participants: 98 participants from tribe A, 93 participants from tribe B, and 97 participants from tribe C. The overall enrollment was 32% of all possible selected participants. We were unable to contact 48% of possible participants. Reasons for noncontact included inactive telephone numbers and absence from home. Ten percent were unable to have an eye examination on the dates of testing. Another 10% scheduled an appointment but did not show up for the examination.

Demographic Characteristics

Table 3 lists the baseline characteristics of the participants.24 We found no age or gender differences between participants and those whom we were unable to contact (P>.05).

Thirty-four (19%) women and 24 (23%) men reported a medical history of diabetes. An additional 5 (2%) participants had previously undiagnosed diabetes with a random capillary blood glucose greater than 127 mg/dL and a hemoglobin A1c greater than 5.7%.14 Forty-six (26%) women and 37 (35%) men reported a medical history of high blood pressure. One hundred twenty (42.1%) participants without a medical history of high blood pressure had a systolic blood pressure greater than 135 mm Hg or a diastolic blood pressure greater than 85 mm Hg.11

Eye Problems in AIAN Populations

Table 4 lists the prevalence of visual impairment, blindness, retinal diseases, cataract, glaucoma, and other eye problems. Under-corrected refractive error was the most common cause of poor visual acuity for both distance vision and near vision. From spectacle correction alone, 18% would gain an improvement from 20/40 or worse to 20/30 or better in their distance vision. Blindness (best-corrected visual acuity 20/200 or worse in the better eye) was found in 1 of 288 participants (0.3%). Visual impairment (best-corrected visual acuity 20/40 or worse in the better eye) was found in 9 of 288 participants (3.1%).

The cause of visual impairment was cataract in 4 persons, age-related maculopathy in 2 persons, glaucoma in 1 person, and multifocal choroiditis in 1 person. One participant with visual impairment refused the full eye examination.

Ocular hypertension was uncommon. Open-angle glaucoma was common, and all participants with glaucoma had “low-tension glaucoma,” defined as an intraocular pressure less than 22 mm Hg. No cases of primary angle-closure suspect, primary angle closure, primary angle-closure glaucoma, or pseudo-exfoliation were found. Other common conditions included age-related maculopathy (16.9%), cataract (12.2%), and diabetic retinopathy (6.0% overall). No participants had clinically significant macular edema from diabetic retinopathy.

Causes of Poor Vision (20/40 or Worse) in Either Eye

Eighteen (6%) right eyes and 20 (7%) left eyes had best-corrected visual acuity of 20/40 or worse. One person with visual acuity worse than 20/40 in both eyes refused a full eye examination, and 2 other persons with visual acuity worse than 20/40 in the left eye refused a full eye examination. The ophthalmologist determined that cataract (n = 7), age-related maculopathy (n = 3), other retinal diseases (n = 6), and glaucoma (n = 1) were the primary causes of poor vision in the right eye. Other retinal diseases included branch retinal vein occlusion, central retinal vein occlusion, macular scar, multifocal choroiditis, cystoid macular degeneration, and chronic retinal detachment, each occurring in 1 right eye. The ophthalmologist determined that the primary causes of poor visual acuity in the left eye were cataract (n = 6), diabetic retinopathy (n = 3), amblyopia (n = 2), age-related maculopathy (n = 1), other retinal diseases (n = 3), and unknown (n = 2). Other retinal diseases included multifocal choroiditis (n = 1) and macular scar secondary to trauma (n = 2). Retinal diseases were the primary cause of poor vision (best-corrected visual acuity of 20/40 or worse) in the right eye for 9 of 17 (53%) participants and in the left eye for 6 of 17 (35%) participants.

Determining prevalence information is an important first step toward meeting the Healthy Vision 2010 objective of decreasing the impact of blindness from diabetes and glaucoma, especially in minority groups such as American Indians/Alaska Natives. Eye and vision problems are the second leading cause of impairment in AIAN populations.25 However, little information exists about the causes of visual impairment and the most common eye problems in AIAN populations.

Visual Impairment

In Northwest AIAN populations, cataract and age-related maculopathy were the most common causes of visual impairment, with a prevalence similar to that found among the White participants in the Baltimore Eye Study2 and the mostly Hispanic participants in Proyecto VER.3 The prevalence of visual impairment among American Indians/Alaska Natives in our study (3.1%) was similar to that among Latinos in the Los Angeles Latino Eye Study (3.0%)5 but higher than that among the mostly White participants in the Beaver Dam Eye Study (0.8%).26 We realize that comparisons with these other prevalence studies present problems. Our study had a small sample size, which resulted in large confidence intervals for our estimates and prevented us from making age–strata comparisons. We recruited only 32% of those people that we randomly selected. Our methods of recruitment may have missed potential participants of lower socioeconomic status because such persons are less likely to have a permanent address or phone number. To decrease this potential bias, future studies should include door-to-door recruitment of eligible participants. Door-to-door recruitment will also allow better ascertainment of ineligible candidates who have moved away or who have otherwise become unavailable. We were unable to measure socioeconomic status in persons who did not participate; however, our results suggest consistency in age and gender of these individuals with the overall AIAN population.

Glaucoma and Ocular Hypertension

One of our intriguing findings was that all patients with glaucoma had intraocular pressure less than 22 mm Hg, otherwise known as low-tension glaucoma.27 Previous studies have shown that low-tension glaucoma may account for up to 69% of all glaucoma in patients with glaucoma.27 In our results, the proportion was even higher (100%). Only 1 study, a recent investigation with Japanese participants, had a similar proportion of low-tension glaucoma (92%).28 We also found a low prevalence of ocular hypertension (0.004%), which is present in approximately 5% of individuals older than 40 years in the US population.29 The Los Angeles Latino Eye Study found ocular hypertension in 3.6% of Latinos.30 The high prevalence of low-tension glaucoma and the low prevalence of ocular hypertension found in our study indicate a need for further analysis in AIAN populations of ocular factors (corneal thickness, intraocular pressure, optic disc characteristics) and risk factors for glaucoma (systemic hypertension, diabetes).

Other Vision Studies in AIAN Populations

The results of our study show similarities with and differences from the results of other vision studies in AIAN populations, which have mostly consisted of chart reviews or convenience samples at a local village. In particular, angle-closure glaucoma was not found in our study but has been found to be a common cause of blindness in Alaskan Eskimos by previous studies.7,8 Diabetic retinopathy was a common eye condition in our study but not a common cause of visual impairment, a finding that contrasts with studies in Navajos and Pima Indians.6,31,32 We found no cases of psuedoexfoliation, a risk factor for open-angle glaucoma, a finding contrary to results among Navajo Indians, among whom 38% of persons 60 years and older had psuedoexfoliation.33 However, our results are similar to those of other studies of AIAN populations that showed cataracts to be a common cause of visual impairment.32 To our knowledge, age-related maculopathy has not been shown to be a common cause of visual impairment in AIAN populations. Overall, these findings suggest heterogeneity in AIAN populations that is probably related to variations in genetics, environment, diet, and other factors.

Refractive Error

We found a great need for eyeglasses in the study population. Eighteen percent of participants had distance vision worse than 20/40, and approximately 30% had near vision worse than Jaeger 4 (20/40 for near vision) owing to undercorrected refractive error. The need for eyeglasses for distance vision (18%) was more common than that found by the Baltimore Eye Study (Blacks, 6.5%; Whites, 7.8%).1 This finding could be related to underuse of eye care providers or the known high prevalence of astigmatism in AIAN populations.34–37 Poor vision from refractive error restricts otherwise healthy individuals from succeeding in educational endeavors and employment opportunities, propagating low educational attainment and poverty; it limits social interaction that requires good distance vision and artisan work that requires good near vision, work such as beadwork and jewelry making. Future interventions addressing vision should include the provision of spectacles for refractive error.

Diabetes and High Blood Pressure

We found a high prevalence of diagnosed and undiagnosed diabetes among our study population. Similarly, high blood pressure (defined as systolic blood pressure >135 mm Hg or diastolic pressure > 85 mm Hg) was common. Our finding of a high prevalence of undiagnosed hypertension should be viewed with caution, because a high proportion of cases may have been “white coat” hypertension, caused by anxiety experienced while answering a questionnaire and undergoing multiple tests. Follow-up and further analysis of participants with undiagnosed hypertension is warranted.


Our pilot study showed a higher prevalence of visual impairment and low-tension glaucoma among American Indians/Alaska Natives compared with among other racial and ethnic groups. American Indians/Alaska Natives have an unmet need for vision correction. Interventions for vision among American Indians/Alaska Natives may include provision of spectacles for refractive error, detection of glaucoma, and prevention of visual impairment from cataracts and age-related maculopathy. Future studies will require larger sample sizes to increase the accuracy of prevalence estimates in AIAN populations.

TABLE 1— Referral Criteria for Follow-Up Examination: Northwest American Indians and Alaska Natives (N = 288)
TABLE 1— Referral Criteria for Follow-Up Examination: Northwest American Indians and Alaska Natives (N = 288)
History of glaucoma, diabetes, or eye abnormalities
Capillary blood glucose glucometer reading > 127 mg/dL random and capillary hemoglobin A1c > 5.7%14
Visual acuity 20/40 or worse with best correction
Intraocular pressure > 21 mm Hg
Limbal chamber depth ≤ 25% of the corneal optical section12,13
Abnormal, unreliable, or indeterminate frequency-doubling technology perimeter result
Difficulty with confocal scanning laser ophthalmoscopy imaging or contour line placement
Borderline or abnormal report from confocal scanning laser ophthalmoscopy according to Moorfields criteria15
Signs of optic nerve disease, diabetic retinopathy, macular degeneration, or other eye disease with nonmydriatic digital imaging
TABLE 2— Case Definitions for Eye Disease: Northwest American Indians and Alaska Natives (N = 288)
TABLE 2— Case Definitions for Eye Disease: Northwest American Indians and Alaska Natives (N = 288)
Eye AbnormalityDefinition
    Mild to moderateSmall microaneurysms, minimal venous changes, and IRMA17
    SevereContains 1 of the 3 characteristics of the 4:2:1 rule: (1) approximately 20 dot-blot hemorrhages in all 4 midperipheral quadrants, (2) venous beading in 2 quadrants, or (3) severe IRMA in 1 quadrant17
    Very severeContains 2 of the 3 characteristics of the 4:2:1 rule17
    High riskNeovascularization of one third of the area of the optic disc or vitreous hemorrhage associated with neovascularization of any part of the eye of one half disc diameter in area18
    Low riskNeovascularization without high-risk characteristics18
CSMERetinal edema within 500 microns of the fovea, exudates associated with retina edema within 500 microns of the fovea, or retinal edema 1500 microns in diameter within 1500 microns of the fovea19
Diabetic retinopathyPresence of NPDR, PDR, or CSME
    EarlySoft drusen > 125 microns, or drusen with pigmentary changes without late ARM, not caused by any other disorder
    LateMacular fluid, geographic atrophy, or neovascular maculopathy within the macula, not caused by any other disorder20
    Category 1Cup-to-disc ratio ≥ 0.8 or glaucomatous optic disc features (rim thinning, nerve fiber defect, excavation) and definite glaucomatous visual field loss
    Category 2Cup-to-disc ratio ≥ 0.8 or glaucomatous features and inability to complete visual field testing satisfactorily
    Category 3Visual field testing not possible and optic disc unable to be viewed, with either IOP > 22 mm Hg or evidence of glaucoma surgery21
OHTNIOP > 22 mm Hg without GON22
PACSPosterior trabecular meshwork cannot be seen in 3 or more quadrants by gonioscopy21
PACPACS with peripheral anterior synechiae, OHTN, or signs of acute angle closure without glaucomatous optic neuropathy21
CataractPseudophakia, aphakia, or vision ≤ 20/40 associated with lens opacities (LOCSIII score ≥ 2.0 for cortex, posterior subcapsular, or nuclear or hypermature cataract) without any other causes of vision loss23
Poor visual acuity caused by undercorrected refractive error
    Distance visionAfter manifest refraction, improvement of distance visual acuity at presentation from 20/40 or worse to 20/30 or better
    Near visionAfter manifest refraction, improvement of near visual acuity at presentation from Jaeger 4 or worse to Jaeger 3 or better
Need for spectaclesUndercorrected refractive error or current use of spectacles
Visual impairmentBest-corrected visual acuity 20/40 or worse in the better-seeing eye17
Blindness at presentation with best correctionBest-corrected distance visual acuity 20/200 or worse in the better-seeing eye1

Note. NPDR = nonproliferative diabetic retinopathy; IRMA = intraretinal microvascular angiopathy; PDR = proliferative diabetic retinopathy; CSME = clinically significant diabetic macular edema; ARM = age-related maculopathy; GON = glaucomatous optic neuropathy; IOP = intraocular pressure; OHTN = ocular hypertension; PACS = primary angle-closure suspect; PAC = primary angle closure; PACG = primary angle-closure glaucoma; LOCSIII = Lens Opacity Classification System III.

TABLE 3— Demographic Characteristics: Northwest American Indians and Alaska Natives (n = 288)
TABLE 3— Demographic Characteristics: Northwest American Indians and Alaska Natives (n = 288)
 No. (%)
    Male106 (36.8)
    Female182 (63.2)
Age, y
    40–49116 (40.3)
    50–5983 (28.8)
    60–6949 (17.0)
    ≥ 7040 (13.9)
Marital status
    Married132 (45.8)
    Other150 (52.1)
    Unknown6 (2.1)
    < HS/GED45 (15.6)
    HS/GED79 (27.4)
    > HS/GED159 (55.2)
    Unknown5 (1.7)
    Yes162 (56.3)
    No121 (42.0)
    Unknown5 (1.7)
Income, % povertya
    < 10049 (17.0)
    101–15052 (18.1)
    151–20035 (12.2)
    > 200127 (44.1)
    Unknown25 (8.7)
Percentage AIAN
    ≤ 25%37 (12.8)
    > 25%–50%49 (17.0)
    > 50% to < 100%79 (27.4)
    100%104 (36.1)
    Unknown19 (6.5)

Note. HS = high school; GED = general equivalency diploma; AIAN = American Indian/Alaska Native.

aAccording to 2001 federal poverty level.24

TABLE 4— Prevalence of Common Eye Problems: Northwest American Indians and Alaska Natives (N = 288)
TABLE 4— Prevalence of Common Eye Problems: Northwest American Indians and Alaska Natives (N = 288)
Eye ProblemaOverall, % (95% CI)Right Eye, % (95% CI)Left Eye, % (95% CI)
Undercorrected refractive error
    Distance vision18.1 (13.6, 22.6)13.2 (9.2, 17.2)11.5 (7.7, 15.3)
    Near vision30.6 (25.2, 36.0)21.5 (16.7, 26.3)23.6 (18.6, 28.6)
Blindness0.3 (0.0, 1.0). . .. . .
Visual impairment3.1 (1.0, 5.0). . .. . .
Age-related maculopathy
    Early16.9 (12.5, 21.3)16.8 (12.4, 21.2)17.2 (13.1, 22.1)
    Late1.4 (0, 2.8)1.3 (0, 2.6)0.4 (0, 1.1)
Cataract12.2 (8.3, 16.1)10.4 (6.8, 14.0)10.0 (6.5, 13.5)
Glaucoma6.2 (2.6, 7.8)3.6 (1.4, 5.8)6.1 (3.3, 8.9)
Ocular hypertension0.004 (0, 1.1)0.004 (0, 1.1). . .
Diabetic retinopathy
    Nonproliferative diabetic retinopathy4.2 (1.8, 6.6)4.0 (1.7, 6.3)4.0 (1.7, 6.3)
    Proliferative diabetic retinopathy1.8 (0.2, 3.4)1.8 (0.2, 3.4)1.8 (0.2, 3.4)

Note. CI = confidence interval.

aTable 2 contains case definitions of eye problems.

This study was supported by the American Glaucoma Society, Alcon, Allergan, and the National Eye Institute (grant NEI 1 K23 EY0155501-01 to S.L.M.), the Lions Sight and Hearing Foundation (grant to C.A.J.), the Center for Healthy Communities (grant to T.M.B. and S.L.M), the Peel Medical Research Trust (grant to B. E.), and the TFC Frost Charitable Trust (grant to B. E.).

This study was presented in part at the 14th Annual Meeting of the American Glaucoma Society, Sarasota, Fla, March 4–7, 2004.

We thank Shaban Demirel, Peter Francis, Cindy Blachly, Judy Thompson, Kathryn Sherman, Douglas Romero, and Karin Novitsky for assistance with data collection.

Human Participant Protection The institutional review boards of the Portland Area Indian Health Service and Legacy Health System approved this pilot study. The leadership committees of the participating tribes signed tribal resolutions allowing us to perform the study. All identifying information was kept confidential. The participants signed a consent form.


1. Tielsch JM, Sommer A, Witt K, Katz J, Royall RM. Blindness and visual impairment in an American urban population: the Baltimore Eye Survey. Arch Ophthalmol. 1990;108:286–290. Crossref, MedlineGoogle Scholar
2. Sommer A, Tielsch JM, Katz J, et al. Racial differences in the cause-specific prevalence of blindness in east Baltimore. N Engl J Med. 1991;325:1412–1417. Crossref, MedlineGoogle Scholar
3. Rodriguez J, Sanchez R, Munoz B, et al. Causes of blindness and visual impairment in a population-based sample of US Hispanics. Ophthalmology. 2002;109: 737–743. Crossref, MedlineGoogle Scholar
4. Klein R, Wang Q, Klein BE, Moss SE, Meuer SM. The relationship of age-related maculopathy, cataract, and glaucoma to visual acuity. Invest Ophthalmol Vis Sci. 1995;36:182–191. MedlineGoogle Scholar
5. Varma R, Ying-Lai M, Klein R, Azen SP. Prevalence and risk indicators of visual impairment and blindness in Latinos: the Los Angeles Latino Eye Study. Ophthalmology. 2004;111:1132–1140. Crossref, MedlineGoogle Scholar
6. Friederich R. Eye disease in the Navajo Indians. Ann Ophthalmol. 1982;14:38–40. MedlineGoogle Scholar
7. Van Rens GH, Arkell SM, Charlton W, Doesburg W. Primary angle-closure glaucoma among Alaskan Eskimos. Doc Ophthalmol. 1988;70:265–276. Crossref, MedlineGoogle Scholar
8. Arkell SM, Lightman DA, Sommer A, Taylor HR, Korshin OM, Tielsch JM. The prevalence of glaucoma among Eskimos of northwest Alaska. Arch Ophthalmol. 1987;105:482–485. Crossref, MedlineGoogle Scholar
9. Behavioral Risk Factor Surveillance System Survey Questionnaire. Atlanta, Ga: Centers for Disease Control and Prevention, US Dept of Health and Human Services; 2001. Available at: http://www.cdc.gov.bfrss. Accessed October 2002. Google Scholar
10. Mangione CM, Lee PP, Gutierrez PR, Spritzer K, Berry S, Hays RD. Development of the 25-item National Eye Institute Visual Function Questionnaire. Arch Ophthalmol. 2001;119:1050–1058. Crossref, MedlineGoogle Scholar
11. Chobanian AV, Bakris GL, Black HR, et al. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension. 2003;42:1206–1252. Crossref, MedlineGoogle Scholar
12. Foster PJ, Devereux JG, Alsbirk PH, et al. Detection of gonioscopically occludable angles and primary angle closure glaucoma by estimation of limbal chamber depth in Asians: modified grading scheme. Br J Ophthalmol. 2000;84:186–192. Crossref, MedlineGoogle Scholar
13. Van Herick W, Shaffer RN, Schwartz A. Estimation of width of angle of anterior chamber; incidence and significance of the narrow angle. Am J Ophthalmol. 1969;68:626–629. Crossref, MedlineGoogle Scholar
14. Shaw J, McCarthy D, Zimmet P, Courten MD. Type 2 diabetes worldwide according to the new classification and criteria. Diabetes Care. 2000;23:B5–B10. Crossref, MedlineGoogle Scholar
15. Wollstein G, Garway-Heath DF, Fontana L, Hitchings RA. Identifying early glaucomatous changes: comparison between expert clinical assessment of optic disc photographs and confocal scanning ophthalmoscopy. Ophthalmology. 2000;107:2272–2277. Crossref, MedlineGoogle Scholar
16. Chylack LT Jr, Wolfe JK, Singer DM, et al. The Lens Opacities Classification System III. The Longitudinal Study of Cataract Study Group. Arch Ophthalmol. 1993;111:831–836. Crossref, MedlineGoogle Scholar
17. Diabetic Retinopathy, Preferred Practice Patterns. San Francisco, Calif: American Academy of Ophthalmology; 1998:15. Available at: http://www.aao.org/aao/education/library/ppp/index.cfm. Accessed October 2002. Google Scholar
18. Photocoagulation treatment of proliferative diabetic retinopathy: the second report of diabetic retinopathy study findings. Ophthalmology. 1978;85:82–106. Crossref, MedlineGoogle Scholar
19. Early photocoagulation for diabetic retinopathy. Early Treatment Diabetic Retinopathy Study Research Group. Ophthalmology. 1991;98:766–785. Crossref, MedlineGoogle Scholar
20. Age Related Macular Degeneration, Preferred Practice Patterns. San Francisco, Calif: American Academy of Ophthalmology; 2001. Available at: http://www.aao.org/aao/education/library/ppp/index.cfm. Accessed October 2002. Google Scholar
21. Foster PJ, Buhrmann R, Quigley HA, Johnson GJ. The definition and classification of glaucoma in prevalence surveys. Br J Ophthalmol. 2002;86:238–242. Crossref, MedlineGoogle Scholar
22. Gordon MO, Kass MA. The Ocular Hypertension Treatment Study: design and baseline description of the participants. Arch Ophthalmol. 1999;117:573–583. Crossref, MedlineGoogle Scholar
23. Leske MC, Connell AM, Kehoe R. A pilot project of glaucoma in Barbados. Br J Ophthalmol. 1989;73: 365–369. Crossref, MedlineGoogle Scholar
24. 2001 federal poverty level. Federal Register. 2003; 68: 6456–6458. Available at: http://aspe.hhs.gov/poverty/03poverty.htm. Accessed October 2002. Google Scholar
25. LaPlante MP. Health conditions and impairments causing disability. Disability Statistics Abstract, No. 16. September 1996. US Dept of Education, National Institute on Disability and Rehabilitation Research (NIDDR). P. 2. Available at: http://dsc.ucsf.edu/pub_listing.php?_type=abstract. Accessed October 2002. Google Scholar
26. Klein R, Klein BE, Linton KL, De Mets DL. The Beaver Dam Eye Study: visual acuity. Ophthalmology. 1991;98:1310–1315. Crossref, MedlineGoogle Scholar
27. Werner EB. Normal-tension glaucoma. In: Ritch R, Shields MB, Krupin T, eds. The Glaucomas. St Louis, Mo: Mosby; 1996:780–781. Google Scholar
28. Iwase A, Suzuki Y, Araie M, et al. The prevalence of primary open-angle glaucoma in Japanese: the Tajimi Study. Ophthalmology. 2004;111:1641–1648. MedlineGoogle Scholar
29. Tielsch JM, Katz J, Singh K, et al. A population-based evaluation of glaucoma screening: the Baltimore Eye Survey. Am J Epidemiol. 1991;134:1102–1110. Crossref, MedlineGoogle Scholar
30. Varma R, Ying-Lai M, Francis BA, et al. Prevalence of open-angle glaucoma and ocular hypertension in Latinos: the Los Angeles Latino Eye Study. Ophthalmology. 2004;111:1439–1448. Crossref, MedlineGoogle Scholar
31. Rearwin DT, Tang JH, Hughes JW. Causes of blindness among Navajo Indians: an update. J Am Optom Assoc. 1997;68:511–517. MedlineGoogle Scholar
32. Schwab IR, Dawson CR, Hoshiwara I, Szuter CF, Knowler WC. Incidence of cataract extraction in Pima Indians: diabetes as a risk factor. Arch Ophthalmol. 1985;103:208–212. Crossref, MedlineGoogle Scholar
33. Faulkner HW. Pseudo-exfoliation of the lens among the Navajo Indians. Am J Ophthalmol. 1971;72: 206–207. Crossref, MedlineGoogle Scholar
34. Grosvenor T. What causes astigmatism? J Am Optom Assoc. 1976;47:926–932. MedlineGoogle Scholar
35. Pensyl CD, Harrison RA, Simpson P, Waterbor JW. Distribution of astigmatism among Sioux Indians in South Dakota. J Am Optom Assoc. 1997;68:425–431. MedlineGoogle Scholar
36. van Rens GH, Arkell SM. Refractive errors and axial length among Alaskan Eskimos. Acta Ophthalmol (Copenh). 1991;69:27–32. Crossref, MedlineGoogle Scholar
37. Luneburg R. Practice among American Indians: study of clinical findings. Opt J Rev Optom. 1975;112: 40–46. Google Scholar


No related items




Steven L. Mansberger, MD, MPH, Francine C. Romero, PhD, Nicole H. Smith, BS, Chris A. Johnson, PhD, George A. Cioffi, MD, Beth Edmunds, FRCOphth, Dongseok Choi, PhD, and Thomas M. Becker, PhDSteven L. Mansberger, Beth Edmunds, Chris A. Johnson, and George A. Cioffi are with the Devers Eye Institute/Discoveries in Sight at Legacy Health System, Portland, Ore. Francine C. Romero is with the Northern Plains Tribal Epidemiology Center in Aberdeen, SD. Steven L. Mansberger, Nicole H. Smith, Dongseok Choi, and Thomas M. Becker are with the Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, Ore. “Causes of Visual Impairment and Common Eye Problems in Northwest American Indians and Alaska Natives”, American Journal of Public Health 95, no. 5 (May 1, 2005): pp. 881-886.


PMID: 15855469