Observed versus indirect estimates of incidence of open-angle Glaucoma

Incidence data on open-angle glaucoma (OAG) are limited and difficult to obtain. To date, few studies have reported incidence directly measured from population-based cohorts. Other reported estimates have been derived indirectly from age-specific prevalence by using several assumptions, and their validity is unknown. To the authors' knowledge, this report presents the first comparison of observed versus indirect estimates of OAG incidence based on data from the population-based Barbados Incidence Study of Eye Diseases (1992-1997) (n= 3,427; 85 percent participation). The observed 4-year incidence of OAG was 1.2 percent (95 percent confidence interval (CI):ages 60-69 years, and 4.2 percent (95 percent CI: 2.6, 6.3 percent) in persons at ages 70 or more years. When incidence was calculated from the prevalence data, power function fitting achieved a closer approximation to observed incidence than did logistic curve fitting. Calculated incidence rate for each group were similar when assuming mortality that was equal (incidence rate= 0.7, 1.3, 2.3, and 4.8 percent) or differential (incidence rate= 0.7, 1.2, 2.4, and 4.8 percent). Other nonlogistic approaches also increased the resemblance of observed and calculated estimates. The absence of longitudinal data, reasonably valid incidence estimates of OAG were obtained from available prevalence data. These estimation techniques can be useful when OAG incidence estimates are required for research or public health purposes. (AU)

Incidence of open-angle glaucoma. The Barbados Eye studies

OBJECTIVE: To measure the 4-year risk of open-angle glaucoma (OAG) in a black population. DESIGN: Population-based cohort study with 4 years of follow up. SETTING: Simple random sample of residents of Barbados, West Indies, aged 40 years or older. PARTICIPANTS: A total of 3427 members of the cohort (85 percent of those eligible). MAIN OUTCOME MEASURE: Development of glaucoma visual field defects and optic disc damage, confirmed by automated perimetry, independent fundus photographic gradings, and standardized opthalmologic examinations. RESULTS: The 4-year risk of OAG in black participants was 2.2 percent (95 percent confidence interval, 1.7 percent-2.8 percent), based on 67 newly developed cases of OAG. Incidence rates increased from 1.2 percent at ages 40 to 49 years to 4.2 percent at ages of 70 years or more, tending to be higher in men than women (2.7 percent vs 1.9 percent). About half of the incident cases were undiagnosed previously, and the rest were receiving OAG treatment. Of the 67 new cases of OAG, 32 had intraocular pressure of 21 mm HG or less at baseline (1.2 percent incidence) and 35 had higher pressures (9 percent incidence). Risk was the highest among persons classified as having suspect OAG at baseline (26.1 percent), followed by those with ocular hypertension (4.9 percent and lowest in the remining population (0.8 percent). CONCLUSIONS: This longitudinal study provides new information on OAG risk, as well as the first incidence measurement in a black population. Although intraocular pressure increased risk, about half of the new cases had baseline pressures of 21 mm Hg or less. Results substantiate the high OAG risk in the population of African origin, especially in older adults; the relative role of intraocular pressure; and the considerable underdetecion of new disease after 4 years of follow-up. (AU)

Incidence of open-angle glaucoma and blood pressure [abstract]

PURPOSE: The relationship of open-angle glaucoma (OAG) to blood pressure (BP) is uncertain, with inconsistent result reported. clarification is needed because vascular factor may influence OAG incidence, but only OAG prevalence between data has been available. In addition, few analyses have accounted for the correlation between BP and intraocular pressure (IOP), or for the effects of antihypertensive treatment (AHT) and IOP-lowering treatment. We describe the role of BP as a risk factor for the 4-year incidence of OAG in Barbados Incidence of Eye Disease (BISED) participants of African descent, while controlling for relevant variables. METHODS: BISED re-examined 3,427 or 85 percent of eligible members of a population-based cohort, 4 years after baseline. The protocol included two BP measurements (random zero sphygmomanometer). Applanation tonometry, Humphrey perimetry; stereo disc photos (graded at the Reading Center); an interview and an ophthalmological examination. OAG criteria required visual field and disc damage, with opthalmological confirmation. The results are reported as ajusted relative risks (RR) from logistic regression analyses. RESULTS: The 4-year OAG incidence was 2.2 percent (n=67.2989 at risk). While the RR increased markedly with IOP, it tended to decrease with systolic BP. The RR for SBP 140 mmHg at baseline, with or without AHT, was 0.5(95 percent Confidence Interval; w/AHT = 0.23, 1.08; w/o AHT = 0.26, 1.03). Hypertension (BP>140/90 mmHg or AHT) reduced OAG risk (RR = 0.48 (0.28, 0.82)). Consistent results were found evaluating perfusion pressure (PP), as persons with lower PP were at higher risk of OAG (RR:SPP<101 mmHg=2.6 (1.3,4.9); DPP<55 mmHg=3.2 (1.6, 6.6): mean PP<42=3.1 (1.6, 6.0). Results were similar when stratifying by age or IOP. CONCLUSION: The 4-year risk of OAG in the cohort was decreased by one-half in those with hypertension at baseline. Risk tended to decreased as SBP increased. Persons with lower SPP, DPP or mean PP had 2-3 times increased OAG risk. Results may have implications for OAG pathogenesis and assessment of risk. (AU)

Prevalence of open angle Glaucoma in a diabetic population in Martinique [abstract]

PURPOSE: To determine the prevalence of open angle glaucoma in a hospital based sample of diabetic patients living in Martinique. METHOD: A retrospective study was conducted over 23 months. A total of 917 diabetic patients were examined, and received complete eye examination. A chart was established with all examination data, patient ID, non-ophthalmological data (blood pressure, body mass index, type of diabetes...) and ophthalmological data with intraocular pressure and optic disc cup. RESULT: Glaucoma was present in about 9.8 percent of patients and there were 3.28 times more females than males. With the type of diabetes: 1.11 percent were Type 1, 18.89 percent were type 2, and 80 percent were insulin treated but not all insulin dependent. CONCLUSION: The prevalence of the dibetic retinopathy is similar in the glaucomatous group to that in the non-glaucomatous group. High blood pressure was present in 80 percent of glaucoma patients versus 58.8 percent in the non-glaucoma group. The 9.8 percent prevalence of glaucoma represents the first data on open angle glaucoma ever measured in Martinique. High blood pressure is a major risk factor for glaucoma in Martinique. Diabetes also represents a risk factor for glaucomas in Martinique. The female:male ratio was 3:1. (AU)

"Back from the brink": benign intracranial hypertension [abstract]

Benign intracranial hypertension (BIH) is a misnomer. The prefix underscores the fact that the condition can cause irreversible blindness. BIH is an enigmatic condition, which can be associated with ingestion of various substances such as excess vitamin A, nalidixic acid, steroids and tetracyclines. It can also be produced by diverse conditions such as dural sinus thrombosis and sleep apnoea. A case is presented which emphasizes the gravity of the condition and the damage that can ensue to the optic nerves. The management needs to be aggressive if this damage is to be minimized and halted. BIH appears to be more common that previously thought and clues are emerging as to its aetiology particularly in relation to sleep apnoea. This demonstrates that the optic nerves, structurally or metabolically, can be subject to influences from a number of systemic conditions. By extrapolation, it begs the question as to whether another opthalmic conundrum - the optic neuropathy of chronic open angle glaucoma - may have some parallels with the pathogenesis of BIH. In particular, it suggests that a broader prospective should be taken in seeking the pathogenesis of chronic open angle glaucoma. (AU)

Longitudinal changes in IOP and incident glaucoma in the Barbados Eye Studies

PURPOSE: There are a few longitudinal population studies describing the progression of intraocular pressure (IOP) or the risk of developing incident open-angle glaucoma (OAG). This report examines changes in IOP and measures the incidence of IOG over a 4-year period in the population of the Barbados Eye Studies. METHODS: The Barbados Incidence Study of Eye Disease (BISED) re-examined members of the Barbados Eye Study (BES) cohort, the original sample being based on a simple random sample of the country's population aged 40 - 84 years. At both visits patients had applanation tonometry, automated Humphrey perimetry, a comprehensive opthalmological examination, colour stereo fundus photography, blood pressure and anthropometric measurements and a detailed interview. RESULTS: A total of 3427 participants or 85 percent of the eligible cohort were re-examined in BISED. The IOP analyses were based on the subset of 2640 Black participants without glaucoma (OAG, or other type) or history of IOP lowering treatment at either visit. The mean age at follow-up was 55 years and 60 percent were women. Mean IOP was 17.3 mmHg (SDñ3.0, median 17.0) at baseline and increased by 2.6 mmHg (SDñ3.6 mmHg, median 2.3)(p<0.001by paired 1 test) in 4 years. Factors positively associated with longitudinal increases in IOP include age (p=0.001) and baseline hypertension (p=0.014) or high systolic blood pressure(p=0.005), while there was an inverse association with baseline IOP. Among the 2989 Black participants without OAG at baseline,the 4-year incidence of OAG was 2.2 percent (95 percent CI: 1.7 percent, 2.8 percent). Incidence was highest among persons classified as suspect OAG at baseline (26.1 percent) followed by ocular hypertensives with IOP >21 mmHg (4.9 percent) and lowest in persons with normal / other diagnoses and with IOP ó21 mmHg (0.8 percent). However, 32 of the 67 new cases of OAG (48 percent) had IOP ó21 at baseline. CONCLUSION: Significant increases in IOP were seen at 4-year follow-up in persons without glaucoma or IOP-lowering treatment history. While high IOP increases the risk of OAG, almost half of the incident cases had IOPó21mmHg at baseline. These results highlight the importance of prognostic factors, other than IOP, in determining the development of OAG.(AU)

Prevalence of open angle glaucoma in a diabetic population in Martinique

OBJECTIVE: To determine the prevalence of open angle glaucoma in a hospital-based sample of diabetic people living in Martinique. DESIGN: Retrospective study during 23 months. PARTICIPANTS: A total of 917 patients were examined and received a complete eye examination for diabetes. MAIN OUTCOME MEASURES: A form was established with all examination data, patient ID, non ophthalmological data (blood pressure, body mass index, type of diabetes...) and ophthalmological data with intra-ocular pressure and optic disc cup. RESULTS: Glaucoma was present in about 9.8 percent of patients and there were 3.28 times more females than male. With regard to the type of diabetes, 1.11 percent were type 1, 18.89 percent were type 2, and 80 percent were insulin treated but not all insulin dependent. The prevalence of diabetic retinopathy is similar in the glaucomatous group and in the non-glaucomatous group. High blood pressure was present in 80 percent of glaucoma patients versus 58.8 percent in the non-glaucoma group. CONCLUSION: This 9.8 percent prevalence of glaucoma is the only data on open angle glaucoma so far available in Martinique. High blood pressure is a main risk factor for glaucoma in Martinique. Diabetes represents also a risk factor for glaucoma in Martinique. The sex ratio showed 3 times more females than males in the diabetic population. (AU)

Glaucoma in a general ophthalmic practice in Trinidad and Tobago

This study is a retrospective look at the records of all patients seen over a three-year period at two locations in Trinidad. There were more males (59 percent) than females; East Indians comprised 33 percent and Negroes 29 percent. 69 percent were self-referrals, optometrists referred 11 percent and general practitioners, 13 percent. Chronic open angle glaucoma was the most common diagnosis (55 percent) among patients presenting for the first time; glaucoma was suspected in 24 percent, narrow angle glaucoma in 10 percent.(AU)

Diagnosis and management of a silent blinding disease in melanoderms: chronic (primary) open angle glaucoma

In melanoderms it is estimated that over 10 percent of the adult population is afflicted with open angle glaucoma. This disease is painless, chronic and gradually reduces vision leading eventually to blindness. There is no cure but with early diagnosis, patient education and treatment glaucoma is controllable. The anatomy, physiology, and pharmacology of the eye will be discussed. Surgical management will also be discussed as well as the social and economic effects of this disease in developing countries.(AU)

Distribution of intraocular pressure: the Barbados Eye Study

OBJECTIVE: To provide data on the distribution of intraocular pressure (IDP) in a predominantly black population, which has a high prevalence of open-angle glaucoma. DESIGN: Population-based prevalence study. SETTING AND PARTICIPANTS: Participants (N = 4601) (age range, 40-84 years) who had undergone applanation tonometry measurements in the Barbados Eye Study. Self-reported race was 93 percent black, 4 percent mixed (black and white), and 3 percent white or other. DATA COLLECTION: A standardized protocol included applanation tonometry and other ocular measurements, fundus photography, demographic data, and an interview. MAIN OUTCOME MEASURES: The average of 3 IDP measurements at the Barbados Eye Study visit was used to compare IDP by self-reported race. Descriptive data on IDP by age, sex, glaucoma status, and cup-disc ratio were examined in the black population. RESULTS: The IDP was highest in the population of African origin. The mean (+/-SD) IDP values for black, mixed, and white participants were 18.7 +/- 5.2, 18.2 +/-3.8, and 16.5 +/- 3.0 mm Hg, respectively. An IDP greater than 21 mm Hg was present in 18.4 percent, 13.6 percent and 4.6 percent of the black, mixed and white participants, respectively. In analyses that were adjusted for age, sex, and glaucoma status, such values were 5 times as likely in black than white participants and 3.5 times as likely in mixed race participants (p < .01). Among the black participants, the mean IDP increased approximately 1 mm Hg for every increase in 10 years of age. After excluding persons with any type of glaucoma, suspected glaucoma, or a history of glaucoma treatment, women had significantly (P < .01) higher IDP values; however, no significant IDP trends by sex were evident in the group with glaucoma. The IDP was also positively associated (P < .05) with vertical cup-disc ratios. After 2 visits, the IDP remained 21 mm Hg or less in 21 percent of the persons with glaucoma vs 64 percent of those without glaucoma. CONCLUSIONS: In the black participants, the IDP was higher than in the white participants. The IDP was also associated with age and cup-disc ratios. The results showed that open-angle glaucoma and a high IDP alone have a different distribution by sex; although open-angle glaucoma was more frequent in men, ocular hypertension was more frequent in women. These data have implications for the detection and causation of open-angle glaucoma in this high-risk population.(AU)

Analyses of reported family history of glaucoma: a preliminary investigation: the Barbados Eye Study Group

This study investigated the self-reported family history of open-angle glaucoma (OAG) among 4,314 black participants in the Barbados Eye Study (BES), which was based on a random sample of Barbados-born citizens between 40 and 84 years of age. Data collection included Humphrey perimetry, fundus photography various ophthalmic and other measurements and a comprehensive interview, including family history. Results showed that participants with OAG and previus OAG treatment reported more family history; maternal history was repored twice as often as paternal history. In persons without previous OAG treatment, those with newly diagnosed OAG reported more sibling history (Odds Ratio = 4.5). The Statistical Analysis for Genetic Epidemiology (S.A.G.E.) system was used to test the transmission models for OAG in a subset of 1,048 families (5,806 individuals) with the most complete self-reported family information. The S.A.G.E. results are consistent with the existence of a major dominant allele for OAG. These results should be viewed as promising, but preliminary, since they are based on self-reported data. More definitive information is currently being collected by the Barbados Family Study of Open-angle Glaucoma.(AU)

Risk factors for open-angle glaucoma: the Barbados eye study

The objective was to evaluate risk factors for open-angle glaucoma among black participants in the Barbados Eye Study. The design was a population-based study of demographic, medical, ocular, familial, and other factors possibly related to open-angle glaucoma. The setting and participants: The Barbados Eye Study included 4709 Barbados residents identified by a simple random sample of Barbadian-born citizens, 40 to 84 years of age; participation was 84 percent. This report is based on the 4314 black participants examined at the study site; 302 (7 percent) met the Barbados Eye Study criteria for open-angle glaucoma. Data collection included a standardized protocol included applanation tonometry, Humphrey perimetry, fundus photography, blood pressure, anthropometry, and an interview. An ophthalmologic examination was performed for participants who met specific criteria. Main outcome measures: open-angle glaucoma was defined by the presence of both characteristics visual field defects and optic disc damage. Association of open-angle glaucoma with specific factors was evaluated in logistic regression analysis. Results: age, male gender, high intraocular pressure, and family history of open-angle glaucoma were major risk factors; the latter association was stronger in men than women. Lean body mass and cataract history were the only other factors related to open-angle glaucoma. Although hypertension and diabetes were common in Barbados Eye Study participants, they were unrelated to the prevalence of open-angle glaucoma. However, associations were found with low diastolic blood pressure-intraocular pressure differences and low systolic and diastolic blood pressure/intraocular pressure ratios. The Conclusions: In the Barbados Eye Study black population, persons most likely to have open-angle glaucoma were older men and had a family history of open-angle glaucoma, high intraocular pressure, lean body mass, and cataract history. These results suggest the importance of possible genetic or familial factors in open-angle glaucoma. The role of vascular risk factors is consistent with our finding of low blood pressure to intraocular pressure relationships, but the results could be explained by the high intraocular pressure in open-angle glaucoma (AU)

The Barbados eye study

OBJECTIVE: To describe the design of the Barbados Eye Study and report of the prevalence of open angle glaucoma (OAG) in a predominantly black study population. DESIGN: Population-bases prevalence study. SETTING AND PARTICIPATION: Residents of Barbados, West Indies, identified from a simple random sample of Barbadian-born citizens 40 through 84 years old. DATA COLLECTION: Participants had a comprehensive study visit that included automated perimetry, applanation tonometry, and fundus photography; persons with specific findings, as well as a 10 percent sample of participants, were referred for an ophthalmologic exanimation and additional tests. OUTCOME: A diagnosis of OAG required both visual field and optic disc criteria for glaucoma damage after excluding other causes. RESULTS: The 4709 participants (83.5 percent of those eligible) had demographic characteristics that were similar to the census population. Of the 4631 participants who were tested at the study site, 95 percent completed Humphrey automated perimetry and 97 percent had photographic or clinical disc gradings; 93 percent of those referred completed the ophthalmologic examination. In the adult population, the prevalence of OAG by self-reported race was 7.0 percent (302/4314) in black, 3.3 percent (6/184) in mixed race, and 0.8 percent (1/1`33) in white or other participants. In black and mixed-race participants, the prevalence reached 12 percent at age 60 years and older and was higher in men (8.3 percent) than in women (5.7 percent), with and age-adjusted male-female ratio of 1.4. In addition, over 3 percent of the participants were classified as having suspect OAG. CONCLUSIONS: To our knowledge, the Barbados Eye Study is the largest glaucoma study ever conducted in a black population and identified more people with OAG than did any previous population study. The prevalence of OAG was high, especially at older ages and in men. Among participants 50 years old or older, one in 11 had OAG, and prevalence increased to one in six at age 70 years or older. The results highlights the public health importance of OAG in the Afro-Caribbean region and have implications for other populations. (AU)

Posterior lip sclerectomy vs trabeculectomy in West Indian Blacks

Surgical treatment in a West Indian black population with primary open angle glaucoma was randomized to full-thickness posterior lip sclerectomies or partial thickness trabeculectomies. Forty-five posterior lip sclerectomies and 35 trabeculectomies were performed. With a mean follow-up period of 28.3 months, the eyes with posterior lip sclerectomies had lower intraocular pressures, reduced glaucoma medication requirements, and less failures. Decline of visual acuity did not differ significantly between the two groups, but early visual acuity loss due to accelerated cataract formation was noted more frequently with posterior lip sclerectomies. The incidence of flat anterior chambers also did not differ significantly, but shallow anterior chambers were more frequent and persisted for a longer time with posterior lip sclerectomies. Other complications were more frequent with posterior lip sclerectomies. (AU)

A pilot project of glaucoma in Barbados

The prevalence of open-angle glaucoma is believed to be very high among West Indian blacks. To begin investigating the prevalence and risk factors for glaucoma and other eye diseases in Barbados, WI, a pilot study was conducted. The pilot project identified a stratified, random national sample of 300 persons over 35 years of age who were invited to participate in an ophthalmic examination and an interview. Of those contacted 89 percent were eligible and 95 percent of these agreed to participate. The overall glaucoma prevalence in the participants was 6 percent; it was 13 percent among black and mixed persons over 54 years. Age related cataract, hypertension, and diabetes were frequent findings. Although the sample size of the pilot project is small, the results suggest a high prevalence of glaucoma in Barbados, a finding that merits further study. (AU)

Filtration surgery in Black patients: early results in a West Indian population

We reviewed the early results of 80 filtration procedures when used as the initial surgical treatment in a Saint Lucian West Indian black population with primary open angle glaucoma. Two techniques were used: trabeculectomy under a scleral flap with fornix-based conjunctival flap (Group 1) and full thickness posterior lip sclerectomy with limbal-based conjunctival flap (Group 2). Postoperatively, with an average follow-up of six months, Group 2 had significantly lower intraocular pressures, reduced glaucoma medication requirements, and increased cystic pleb formation. Vision did not differ significantly between the two groups postoperatively, although two Group 1 patients developed progressive glaucomaous visual loss. Complications were slightly more frequent in Group 2. The results of this study suggest that a full thickness sclerectomy technique merits consideration as the initial filtration procedure of choice in West Indian blacks with advanced open angle glaucoma.(AU)