Longitudinal glaucoma screening for siblings of patients with primary open angle glaucoma: the Nottingham Family Glaucoma Screening Study

Novel Vertical Cup-to-Disc Classification to Identify Normal Eyes That Maintain Non-Glaucoma Status: A 10-Year Longitudinal Study

PRCIS

We propose a new classification model to serve as a control for future genomic studies of glaucoma by distinguishing normal subjects maintaining non-glaucoma status for 10 years using the vertical cup-to-disc ratio (VCDR).

PURPOSE

This study aimed to develop a classification for distinguishing subjects maintaining non-glaucoma status for 10 years using the VCDR.

PARTICIPANTS AND METHODS

Among 842 volunteers 40 years and older, 421 volunteers participated in the second ophthalmic examination 10 years after their first examination. Each volunteer was diagnosed either as healthy normal or glaucoma suspect (GS) in the first glaucoma screening examinations. The former was further classified into the 3 grades of N1, N2, and N3. Specifically, N1 represented (1) VCDR <0.3; (2) no notching or nerve fiber layer defect; and (3) no undermining, N2 indicated 0.3≤VCDR<0.6 and conditions (2) and (3) of N1; and N3 represented 0.3≤VCDR<0.6 with undermining and condition (2), or 0.6≤VCDR<0.7 and condition (2) of N1. Glaucoma transition rates (GTRs) were evaluated in 421 volunteers who returned to participate after a 10-year period.

RESULTS

GTRs were calculated as 1.3% in both N1 and N2, 3.9% in N3, and 18.2% in GS. The ratio of volunteers in the same category maintenance rate increased from N1 to N3.

CONCLUSION

GTRs were lower in N1 and N2 than in N3 or GS during the 10-year study period. This novel classification of healthy non-glaucoma subjects may help identify those, especially Japanese males, who maintain a non-glaucoma status for an extended period of 10 years.

Do motivational cards really benefit sibling screening of primary open-angle glaucoma probands?

Purpose

To compare the impact of Sibling Motivational Card (SMC) and oral counseling in screening siblings of primary open-angle glaucoma (POAG) probands.

Methods

Two hundred and thirty-four newly diagnosed POAG probands were randomized to receive either oral counseling or SMC to motivate their siblings for a glaucoma screening at a tertiary eye care hospital in South India from July 2015 and June 2017. A total of 116 probands were orally counseled with a standard template of dialogs about the importance of family screening to motivate their siblings for a screening. One hundred and eighteen probands were randomized to receive SMC, bearing the details of the proband, sibling, and a message stressing the importance of family screening, in addition to oral counseling. We assessed the response rate in each group. Additionally, we evaluated the prevalence of POAG in the siblings.

Results

A total of 95 siblings of 234 POAG probands were screened. The mean age distribution was 53.33 ± 10.9 years (range 28-79 years). The male to female ratio was 3:4. The percentage of siblings screened was more in the oral counseling group (63.2%) than in the SMC group (36.8). About 43 (45%) siblings had some form of glaucoma, and 13.6% had POAG. An additional 22.1% were disk suspects, and 5.2% had ocular hypertension.

Conclusion

SMC did not have an additional benefit over the standard oral counseling in promoting sibling screening. Our study stresses the importance of sibling screening in POAG probands. Targeting siblings of POAG probands with oral counseling may offer a relatively inexpensive way of detecting glaucoma.

Analysis of risk allele frequencies of single nucleotide polymorphisms related to open-angle glaucoma in different ethnic groups

BACKGROUND

The prevalence of open-angle glaucoma (OAG) varies from 0.5% to 7.0% among populations of diverse ancestry, suggesting the existence of genetic differences. The purposes of this study were to provide insights into genetic causes of OAG, which can result in prevalence and phenotype differences among populations of diverse ancestry for OAG, and to compare allele frequencies of intraocular pressure (IOP) elevation-related SNPs in OAG among Koreans and other ethnic groups.

METHODS

We collected the data on a total of 135 OAG-associated single nucleotide polymorphisms (SNPs) from a genome-wide association studies (GWAS) catalog. The population-level allele frequencies of these SNPs were derived based on the 1000 Genomes Project and Korean Reference Genome Database. We used Fisher's exact test to assess whether the effect allele at a given SNP was significantly enriched or depleted.

RESULTS

European, American, and South Asian populations showed similar heatmap patterns, while African, East Asian, and Korean populations had distinct patterns. Korean population presented different profiles compared to other groups; rs1579050 (FMNL2 gene), rs2024211 (CAV2;CAV1), and rs8141433 (GNB1L;TXNRD2 gene), which are known to be associated with IOP variation, were enriched in Americans, Europeans, and Africans, and depleted in Koreans. These can be the candidates for the causative genes of differences in the prevalence of IOP variation in OAG according to ethnic groups.

CONCLUSIONS

Differences in allele frequencies associated with IOP related SNPs between Koreans and other ethnicities were observed, which may explain the high prevalence of OAG with normal IOP predominantly in Koreans and East Asians.

A wearable contact lens sensor for noninvasive in-situ monitoring of intraocular pressure

Glaucoma is the second leading cause of blindness in the world. Intraocular pressure (IOP) is a primary indicator of glaucoma which can be measured for the treatment of the disease. This paper presents a piezo-resistive principle pressure sensor to monitor IOP continuously and non-invasively. The sensor is designed based on the Wheatstone bridge circuit and fabricated by the spray-coating method. The hybrid nanomaterials of graphene and carbon nanotubes are introduced as sensing layers which are embedded inside the soft contact lens substrate composed of flexible polydimethyl siloxane (PDMS) and parylene. The sensing performance is discussed followed by a brief description of our sensor design and fabrication. Tests on a PDMS eyeball model indicate that it has a high sensitivity of 36.01 μV mmHg^-1. Also, the frequency response and the ability to track dynamic pressure change cycles are demonstrated in normal IOP variation range from 9 to 34 mmHg. It shows good repeatability and linearity, and can accurately track fluctuating IOP. Thus, this sensor, with its ease of fabrication and simple design, as well as allowance for continuous pressure measurement, offers a promising approach for IOP monitoring in clinical diagnosis of glaucoma.

Screening first-degree relatives of glaucoma patients reveals barriers to participation

PURPOSE

To report the results of a glaucoma screening campaign targeting first-degree relatives of glaucoma patients in South India.

METHODS

1598 glaucoma patients were contacted via letter or letter and phone call and asked to bring their siblings and children to a glaucoma screening. Participants underwent standardised eye examinations and completed questionnaires that assessed barriers to participation and awareness of glaucoma risk. Two-proportion z-tests were used to compare categorical data. Costs associated with the screening were recorded.

RESULTS

206 probands (12.9%) attended the screening along with 50 siblings and children. Probands were nearly twice as likely to attend if they had been contacted via both letter and phone call rather than letter only. Over half of probands reported that their relatives could not participate because they did not live in the region, and one-fifth reported that their relatives had other commitments. Fifty-eight per cent of the siblings and children who attended did not know that they were at increased risk for glaucoma due to their family history, and 32.0% did not know that the relative who had invited them to the screening had glaucoma. Thirteen siblings and children (26.0% of those who attended) were found to have findings concerning for glaucoma. The average cost per first-degree relative who was screened was INR2422 (£26).

CONCLUSION

Participation in this glaucoma screening campaign was poor. The major barrier to participation was distance from the screening site and associated indirect costs. Better strategies for bringing first-degree relatives in for examinations are needed.

Advances in diagnostic applications for monitoring intraocular pressure in Glaucoma: A review

Continuous intraocular pressure (IOP) monitoring for improving glaucoma diagnosis and treatment has remained a challenge for the past 60 years because glaucoma is the second leading cause of irreversible blindness worldwide. Several devices with different measurement principles and recently developed biosensors with semiconductor materials offer exciting properties. However, none of these devices for continuous IOP monitoring have been fully integrated into clinical practice, primarily due to technical problems. This review summarizes state-of-the-art biosensors developed for IOP monitoring by explaining their basic functions and applications, the main technology (pressure transductors, piezoresistive sensors, capacitive sensors, and resonant sensors), measurement approach (noninvasive, minimally invasive or invasive (surgically implantable)), and telemetry characteristics. To provide updated information for clinicians and researchers, we also describe the advantages and limitations of the application of these new sensors to eye care management. Despite significant improvements in IOP biosensor technology, the accuracy of their measurements must be improved to obtain a clear equivalence with actual IOP (measured in units of mmHg) to facilitate their clinical application. In addition, telemetry systems may be simplified to prevent adverse outcomes for patients and to guarantee the safety of stored data.

Heritability of glaucoma and glaucoma-related endophenotypes: systematic review and meta-analysis protocol

INTRODUCTION

Glaucoma is the second leading cause of age-related vision loss worldwide; it is an umbrella term that is used to describe a set of complex ocular disorders with a multifactorial aetiology. Both genetic and lifestyle risk factors for glaucoma are well established. Thus far, however, systematic reviews on the heritability of glaucoma have focused on the heritability of primary open-angle glaucoma only. No systematic review has comprehensively reviewed or meta-analysed the heritability of other types of glaucoma, including glaucoma-related endophenotypes. The aim of this study will be to identify relevant scientific literature regarding the heritability of both glaucoma and related endophenotypes and summarise the evidence by performing a systematic review and meta-analysis.

METHODS AND ANALYSIS

This systematic review will follow the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols 2015 checklist, which provides a standardised approach for carrying out systematic reviews. To capture as much literature as possible, a comprehensive step-by-step systematic search will be undertaken in MEDLINE (PubMed), EMBASE, Web of Science and ScienceDirect, and studies published until 31 December 2017 will be included. Two reviewers will independently search the articles for eligibility according to predefined selection criteria. A database will be used for screening of eligible articles. The quality of the included studies will be rated independently by two reviewers, using the National Health Institute Quality Assessment tool for Observational Cohort and Cross-Sectional Studies. A random-effects model will be used for the meta-analysis. This systematic review is registered with the International Prospective Register of Systematic Reviews with a registration number: CRD42017064504.

ETHICS AND DISSEMINATION

We will use secondary data from peer-reviewed published articles, and hence there is no requirement for ethics approval. The results of this systematic review will be disseminated through publication in a peer-reviewed scientific journal.

Baseline Fourier-Domain Optical Coherence Tomography Structural Risk Factors for Visual Field Progression in the Advanced Imaging for Glaucoma Study

PURPOSE

To identify baseline structural parameters that predict the progression of visual field (VF) loss in patients with open-angle glaucoma.

DESIGN

Multicenter cohort study.

METHODS

Participants from the Advanced Imaging for Glaucoma (AIG) study were enrolled and followed up. VF progression is defined as either a confirmed progression event on Humphrey Progression Analysis or a significant (P < .05) negative slope for VF index (VFI). Fourier-domain optical coherence tomography (FDOCT) was used to measure optic disc, peripapillary retinal nerve fiber layer (NFL), and macular ganglion cell complex (GCC) thickness parameters.

RESULTS

A total of 277 eyes of 188 participants were followed up for 3.7 ± 2.1 years. VF progression was observed in 83 eyes (30%). Several baseline NFL and GCC parameters, but not disc parameters, were found to be significant predictors of progression on univariate Cox regression analysis. The most accurate single predictors were the GCC focal loss volume (FLV), followed closely by NFL-FLV. An abnormal GCC-FLV at baseline increased risk of progression by a hazard ratio of 3.1. Multivariate Cox analysis showed that combining age and central corneal thickness with GCC-FLV in a composite index called "Glaucoma Composite Progression Index" (GCPI) further improved the accuracy of progression prediction. GCC-FLV and GCPI were both found to be significantly correlated with the annual rate of change in VFI.

CONCLUSION

Focal GCC and NFL loss as measured by FDOCT are the strongest predictors for VF progression among the measurements considered. Older age and thinner central corneal thickness can enhance the predictive power using the composite risk model.

A global test for gene-gene interactions based on random matrix theory

Statistical interactions between markers of genetic variation, or gene-gene interactions, are believed to play an important role in the etiology of many multifactorial diseases and other complex phenotypes. Unfortunately, detecting gene-gene interactions is extremely challenging due to the large number of potential interactions and ambiguity regarding marker coding and interaction scale. For many data sets, there is insufficient statistical power to evaluate all candidate gene-gene interactions. In these cases, a global test for gene-gene interactions may be the best option. Global tests have much greater power relative to multiple individual interaction tests and can be used on subsets of the markers as an initial filter prior to testing for specific interactions. In this paper, we describe a novel global test for gene-gene interactions, the global epistasis test (GET), that is based on results from random matrix theory. As we show via simulation studies based on previously proposed models for common diseases including rheumatoid arthritis, type 2 diabetes, and breast cancer, our proposed GET method has superior performance characteristics relative to existing global gene-gene interaction tests. A glaucoma GWAS data set is used to demonstrate the practical utility of the GET method.

Screening First Degree Relatives of Persons with Primary Open Angle Glaucoma in India

PURPOSE

To report the results of screening first degree relatives of persons identified with primary open angle glaucoma in a tertiary eye hospital glaucoma services.

DESIGN

A cross-sectional study of first degree relatives of persons with primary open angle glaucoma.

MATERIALS AND METHODS

First degree relatives of patients identified with primary open angle glaucoma were invited to participate in a screening evaluation in the base hospital to detect glaucoma. All participating individuals had comprehensive eye examination including vision screening, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, frequency doubling peri-metry and dilated fundus examination. Persons with definite and suspected glaucoma were subject to full threshold automated perimetry.

RESULTS

A 514 first degree relatives of 346 persons with primary open angle glaucoma, of 4972 individuals who were invited to participate attended the screening examination (Response Rate 7%). Fifty-five percent of those who attended were males and mean age of participants was 56.8 years. Sixty-eight relatives (13.3% of those screened) were detected to have definite glaucoma. Sixty percent of those detected with definite glaucoma were siblings. Fifteen percent of siblings, 4% of off-springs and 20% of parents who attended the screening examination had definite open angle glaucoma.

CONCLUSION

Prevalence of open angle glaucoma amongst first degree relatives of persons with glaucoma is higher than in the general population as reported in previous studies. Significant barriers, however, exist in the uptake of eye care services among relatives of persons known to have primary open angle glaucoma. How to cite this article: Rajendrababu S, Gupta N, Vijayakumar B, Kumaragurupari R, Krishnadas SR. Screening First Degree Relatives of Persons with Primary Open Angle Glaucoma in India. J Curr Glaucoma Pract 2014;8(3):107-112.

The NEIGHBOR consortium primary open-angle glaucoma genome-wide association study: rationale, study design, and clinical variables

Primary open-angle glaucoma (POAG) is a common disease with complex inheritance. The identification of genes predisposing to POAG is an important step toward the development of novel gene-based methods of diagnosis and treatment. Genome-wide association studies (GWAS) have successfully identified genes contributing to complex traits such as POAG however, such studies frequently require very large sample sizes, and thus, collaborations and consortia have been of critical importance for the GWAS approach. In this report we describe the formation of the NEIGHBOR consortium, the harmonized case control definitions used for a POAG GWAS, the clinical features of the cases and controls, and the rationale for the GWAS study design.

Familial aggregation of primary open angle glaucoma in Shanghai, China

PURPOSE

To identify familial aggregation of primary open angle glaucoma (POAG) in first-degree relatives in Shanghai, China.

METHODS

This was a prospective case-control study. First-degree relatives of 113 POAG patients and 119 normal controls underwent a standardized ophthalmic examination. Each participant was diagnosed as normal, glaucoma suspect or glaucoma. The prevalence of glaucoma and glaucoma suspect in each group was calculated, and the odds ratio (OR) and 95% confidence interval (CI) for family history were estimated using the Generalized Estimating Equations model.

RESULTS

Of 531 first-degree relatives in the case group, 67 (12.62%) were identified to have POAG, a rate eight times higher than that of the control group (8 of 526, 1.52%). In family units, the prevalence OR value of glaucoma was 8.77 (95% CI: 3.73-20.62). The effect of family history on parents, siblings, and offspring of probands was statistically significant, with OR values of 6.92 (95% CI: 1.90-25.18), 11.29 (95% CI: 3.63-35.11), and 11.35 (95% CI: 1.69-76.21), respectively. In the case of glaucoma suspect, a significant effect was found for both family units (OR 5.60; 95% CI: 1.15-27.21) and offspring (10.83 OR; 95% CI: 1.34-87.73).

CONCLUSIONS

In Shanghai, relatives of glaucoma patients have a strongly increased risk of glaucoma, and priorities for glaucoma screening should target this population. The study demonstrates that familial aggregation of POAG transcends racial and cultural boundaries.

Discrete Portable Measuring Device for Monitoring Noninvasive Intraocular Pressure with a Nano-Structured Sensing Contact Lens Prototype

A new portable measuring device for monitoring intraocular pressure with a non invasive system using a prototype of contact lens has been developed. The contact lens is based on a new organic flexible highly piezo-resisitive film sensor that is glued to the central hole of a lens. The measuring system is wire connected to the contact lens and incorporates user interface methods and a Bluetooth link for bi-directional wireless data transfer. The key design aspects of such architecture are discussed in this paper. The system is designed with an architecture that can be integrated in the future in order to be placed in the contact lens. The discrete system is used to validate the electronic measurement operation and the contact lens sensor (CLS). The measurement instrument can calibrate the differences of the nominal value of the sensor and measure resistances variations that are related to pressure variations. The measuring system and the contact lens sensor were tested with an eye phantom and with enucleated pig eyes by applying pressure changes between 7 to 32 mmHg recording the electrical changes with the portable device.

Prevalence and determinants of glaucoma in citizens of qatar aged 40 years or older: a community-based survey

Background:

We present the prevalence and determinants of glaucoma among subjects 40 years of age and older in Qatar.

Materials and Methods:

This community-based survey was held in 2009 at 49 randomly selected clusters. Demographic details and history of glaucoma was collected by the nurses. Ophthalmologists evaluated the optic disc and retina using a digital camera housed in a mobile van. Visual field was tested with an automated perimeter, the intraocular pressure with an applanation tonometer and the angle of the anterior chamber by gonioscopy. A panel of glaucoma experts diagnosed subjects with glaucoma.

Results:

This survey enrolled 3,149 (97.3%) participants. The age- and sex-adjusted prevalence of glaucoma in the population aged 40 years and older was 1.73% (95% confidence intervals [CI] 1.69-1.77). Accordingly, 5,641 individuals in this age group in Qatar would have glaucoma. Chronological age of 60 years and older (Odds ratio [OR] 11.1) and the presence of myopia (OR 1.78) were predictors of glaucoma. Open-angle glaucoma was diagnosed in 44 (65.7%) individuals with glaucoma. In nine (13.4%) and 15 (20.9%) subjects, angle closure glaucoma and other (post-traumatic, pseudoexfoliation) glaucoma were present. Bilateral blindness (vision <3/60) and severe visual impairment (<6/60) were found in four (6%) and three (4.5%) subjects with glaucoma, respectively. Glaucoma was treated in 36 (54%) subjects.

Conclusions:

The prevalence of glaucoma among citizens of Qatar aged 40 years and older was 1.71%. Glaucoma was associated with the age of 60 years and older and the presence of myopia.

Glaucoma among patients enrolled in a national vision care plan

BACKGROUND

Glaucoma is one of the leading causes of impaired vision and blindness in the United States. An understanding of the disease process and its risk factors by patients is essential if its consequences are to be mitigated. Among the known risk factors, family history is one that can help promote awareness for early recognition and treatment among potential patients. This study reports on the responses to a questionnaire by glaucoma patients on their use of vision care, their understanding of their disease, and whether they shared their medical history with other family members.

METHODS

A survey was mailed to members of a national vision care benefits plan who received an eye examination with a diagnosis of glaucoma. Patients were identified by diagnosis through the managed care organization's management information system. A survey instrument was designed to determine family history, use of vision care, medications used, and basic knowledge of glaucoma.

RESULTS

One hundred forty-eight surveys were returned; two thirds were from glaucoma patients and one third from glaucoma suspects. The frequency of eye examinations and the reason for their most recent examination differed between the 2 groups. Most glaucoma patients informed relatives of their condition. As expected, glaucoma patients were better educated than the glaucoma suspect group; however, knowledge of the disease process and its consequences was lacking even among those who were taking glaucoma medication.

CONCLUSIONS

Some glaucoma patients appear to be unaware as to how glaucoma affects their vision. Understanding one's disease can enhance patient compliance and ensure that the patient returns for continued treatment and management. Patients with poor health literacy (especially with a disease with an asymptomatic beginning stage) are at a higher risk for noncompliance.

The heritability and sibling risk of angle closure in Asians

PURPOSE

To describe the heritability and sibling risk for angle closure.

DESIGN

Prospective clinical study.

PARTICIPANTS

Probands with primary angle closure (PAC) and primary angle-closure glaucoma (PACG) and their first-degree relatives.

METHODS

One hundred probands with PAC and PACG and their first-degree relatives were examined prospectively. All subjects underwent an ophthalmic evaluation that included slit-lamp examination, optic disc evaluation, and gonioscopy. An angle was classified as narrow if the posterior (usually pigmented) trabecular meshwork could be seen for less than 180° of the angle circumference. The heritability of narrow angles was calculated by threshold models. The sibling recurrence and relative risk of having narrow angles compared with the general population was calculated using estimation of sibling genetic risk parameters, corrected for single ascertainment bias.

MAIN OUTCOME MEASURES

Heritability and sibling risk for narrow angles.

RESULTS

One hundred probands (consisting of 76 subjects with PACG and 24 with PAC) were examined together with 327 first-degree relatives. There were 76 female probands and 24 male probands. Of the first-degree relatives, 146 were male and 181 were female. Of the 327 first-degree relatives, 105 (32.1%) had narrow angles. The heritability of narrow angles was 58.8% overall, with the genetic variance being 2.30 and the phenotypic variance being 3.91. Of the 515 sibling pairs examined, 171 (33.1%) pairs had both siblings unaffected, 113 (21.9%) pairs had both siblings affected, 231 (45.0%) pairs had 1 sibling affected. The sibling recurrence risk for having narrow angles was 49% (95% confidence interval, 41.6%-56.8%), whereas the sibling relative risk for narrow angles was 7.57 (95% confidence interval, 6.41-8.74).

CONCLUSIONS

A high heritability of narrow angles of almost 60% was found. Siblings of Chinese patients with PAC or PACG have almost a 50% probability of having narrow angles and are more than 7 times more likely to have narrow angles than the general population.

Using the Utah Population Database to assess familial risk of primary open angle glaucoma

PURPOSE

Primary open angle glaucoma (POAG) is a leading cause of irreversible blindness in the elderly. Previous epidemiological studies have identified family history, ethnic origin, age, high intraocular pressure and diabetes mellitus as risk factors. However, it is difficult to assess the extent family history plays in this disease process. The Utah Population Database (UPDB), created by the University of Utah, has recently become a resource for which greater than 9 million records are available for use. The UPDB is divided into two major data sets from which family members can be identified, namely 1.6 million genealogy records and 2 million Utah birth certificates. This study utilizes these resources to assess the familial risk of POAG within the Utah Population.

METHODS

The University of Utah's hospital and clinic records were searched for patients with primary and chronic open angle glaucoma (ICD9 codes 365.04 and 365.11) between the years 1995 and 2005. A case-control analysis was then performed with specialized UPDB software that was modified to constrain the control and pedigree populations to over 1 million University of Utah-UPDB linked records. Controls were matched to cases by gender and birth year (±2.5years) with only one control being used per case. Population-attributable risk (PAR) to familial factors and relative risk (RR) were computed using conditional logistic regression (CLR).

RESULTS

From the original 1.5 million medical records, 6198 patients with glaucoma were identified. Of these, 3391 met the inclusion criteria, which required patients to have at least one parent or one child in the UPDB. The PAR in this population was found to be 0.20, indicating 20% of the risk for glaucoma is attributable to genetic factors. CLR computations also showed a significantly increased relative risk (p<0.05) in first cousins (RR=1.45 (95% confidence interval (CI) 1.16-1.8)), second cousins (RR=1.19 (95% CI 1.08-1.32)), siblings (RR=3.76 (95% CI 2.66-5.31)), parents (RR=6.25 (95% CI 3.94-9.9)) and children (RR=6.77 (95% CI 3.39-13.5)).

CONCLUSIONS

Based on these familial data, there is a significantly higher prevalence of glaucoma in both first and second generation relatives of those affected as compared to relatives in the control group. When compared with other epidemiologic studies, such as an analysis of first-degree relatives of patients from the Rotterdam study, which showed a PAR of 16%, our study actually demonstrates a greater familial contribution to glaucoma. The UPDB is a valuable and unique resource providing a large population from which to analyze the familial risk of glaucoma.

How significant is a family history of glaucoma? Experience from the Glaucoma Inheritance Study in Tasmania

PURPOSE

To determine what proportion of primary open angle glaucoma (POAG) in Tasmania, Australia is familial.

METHODS

Between 1994 and 1996 an audit of Tasmanian patients diagnosed with glaucoma was performed. Identified probands along with their family members were invited to participate. Family history of POAG was noted and pedigrees constructed. Each participant underwent a detailed examination, including visual acuity, intraocular pressure measurement, gonioscopy, optic disc assessment and visual field testing. Participants were classified as normal, suspect or POAG. Data from 467 participants in the Twins Eye Study in Tasmania (TEST) were used as a reference for the general population.

RESULTS

Of 2062 participants examined, 1700 were classified as POAG. A total of 1014 participants (59.6%) belonged to families in which other members were affected (familial glaucoma). Six hundred and fifty-six of these 1014 familial cases (64.8%) had a first-degree relative affected. The number of affected members in the family groups varied from two to 29. Six hundred and eighty-eight participants had no known family history of POAG (sporadic glaucoma). There were significantly more POAG patients with a family history of POAG compared to the TEST population (chi2 = 161.81, P < 0.0001), and for a person with POAG the odds ratio of having a positive family history was 4.1 (95% confidence interval: 3.2-5.2).

CONCLUSION

Approximately 60% of POAG in Tasmania is familial. This percentage is higher than most previous reports of familial glaucoma and emphasizes the importance of genetics in POAG, with major implications for screening and future research.