Anterior chamber depth measurement by optical pachymetry: systematic difference using the Haag-Streit attachments.

BACKGROUND/AIM: Haag-Streit recommends that for the most accurate anterior chamber depth (ACD) results, the corneal thickness, as determined with attachment No I, should be deducted from a measurement from corneal epithelium to the anterior lens surface, made with attachment No II (method A). Often ophthalmologists use the measurement made from the corneal endothelium to the anterior lens surface, using only attachment No II (method B), which is a simpler and faster method. This study examined agreement between methods A and B. METHODS: Two studies were conducted independently by each author. PHA measured 127 (27 men, 100 women; mean age, 66.9 years) consecutive Danish patients referred for evaluation because of possible angle closure. RRB measured 109 subjects (30 men, 79 women; mean age, 61.3 years) consecutively from a population based glaucoma survey in Rom Klao, Thailand. RESULTS: Using method A, mean ACD was 1.97 mm (SD 0.29) in the Danish study and 2.59 mm (SD 0.27) in the Thai study. ACD measured with method B was significantly (p<0.001) deeper than method A in both studies (Danes: difference = 0.118 (95% CI: 0.109 to 0.127); Thais: difference = 0.166 mm (95% CI: 0.158 to 0.174)). With an increase in ACD of 1 mm, the methodological difference increased by 0.052 mm (regression formula: difference (B - A) = 0.0667 x mean ACD - 0.0148; R(2) = 0.31). This positive correlation did not differ significantly between the two studies. CONCLUSIONS: The relevance and importance of estimating ACD as a risk factor in primary angle closure glaucoma suspects and patients has been repeatedly emphasised. This is the first empirical study to quantify the difference in ACD using these two methods in two samples, one clinic based (angle closure suspects) and the other population based. The size of the methodological difference has a level that corresponds to the age reduction of ACD per decade, or to about 6% of ACD in a given eye. These findings highlight the importance of clinicians recognising that these two methods will give different results and recommend that one should standardise ACD measurements using the Haag-Streit optical pachymeter.

Defining "occludable" angles in population surveys: drainage angle width, peripheral anterior synechiae, and glaucomatous optic neuropathy in east Asian people.

BACKGROUND: /aim: A current consensus in epidemiological studies of primary angle closure (PAC) is to diagnose the condition only if the posterior (usually pigmented) trabecular meshwork is seen for less than 90 degrees of the angle circumference, termed an "occludable angle." The authors sought to assess the validity of this epidemiological classification by exploring the relation between drainage angle width, peripheral anterior synechiae (PAS) and glaucomatous optic neuropathy (GON). METHODS: 918 Mongolians and 995 Chinese Singaporeans, both groups aged 40 years and older were examined in two population based surveys. Gonioscopic angle width was graded in five categories (0 = closed to 4 = wide open) according the scheme described by Shaffer. Cases with secondary PAS were excluded. RESULTS: The rate of PAS was between 0.3% and 1.7% in people with wide angles (grades 3 and 4). In those with grade 2 angles, PAS were seen in between 8% of eyes. In eyes with grade 1 angles, the rate rose to 17% in Chinese Singaporeans, and 31% in Mongolians. The odds of PAS were higher in people with narrower angles. However, there was a greater absolute number of people with PAS whose drainage angles were classified as "not occludable" than those classified "occludable." CONCLUSIONS: The traditional view that primary angle closure becomes a significant possibility in drainage angles of < or = grade 2 (approximately 20 degrees ) is valid in east Asians. The definition of an "occludable" angle examined here excludes many people with PAS. This probably serves to underemphasise the role of PAC in population surveys of glaucoma prevalence in Asian people.

Glaucoma in East Greenlandic Inuit--a population survey in Ittoqqortoormiit (Scoresbysund).

PURPOSE: To determine the prevalence of primary angle-closure glaucoma (PACG) in an isolated Greenlandic Inuit community and to examine the anatomical risk factors for this disease. METHODS: All individuals aged > or =40 years were examined. Visual acuity, refractive error, anterior chamber depth (ACD), intraocular pressure (IOP), gonioscopy, and optic disc characteristics were recorded. RESULTS: Seventy-nine individuals (65% response rate) were examined. Mean IOP was 12.0 mmHg. ACD was shallow and decreased with age and hypermetropia. ACD was deeper than observed in the same community in 1981 and another East Greenland population in 1970. Two subjects had definite PACG (2.5 %). CONCLUSION: This is the first study to use applanation tonometry in a Greenland population and confirms a low IOP as found in other populations of Inuit and Mongolians. ACD measured in 1998 was deeper than in 1981 in the same community which may represent a cohort effect indicating a secular change.

Anterior chamber depth measurement as a screening tool for primary angle-closure glaucoma in an East Asian population.

OBJECTIVE: To evaluate anterior chamber depth measurement as a method of screening for primary angle-closure glaucoma in an East Asian population. DESIGN: Two-phase, cross-sectional, community-based study. SETTING: Rural and urban locations in the Hovsgol and Omnogobi provinces, Mongolia. PARTICIPANTS: Nine hundred forty-two (94.2%) of 1000 individuals in Hovsgol(1995) and 775 (96.9%) of 1000 individuals in Omnogobi (1997) aged 40 years or older were examined. MAIN OUTCOME MEASURES: Anterior chamber depth was measured by optical pachymetry, slitlamp-mounted A-mode ultrasound, and handheld ultrasound. Gonioscopy was used to detect occludable angles, defined as one in which the trabecular meshwork was visible for less than 90 degrees of angle circumference. Primary open-angle glaucoma was diagnosed in subjects with an occludable angle and glaucomatous optic neuropathy with visual morbidity. The area under the curve in a receiver operating characteristic plot was used to compare test performance. RESULTS: Optical pachymetry outperformed the slitlamp-mounted ultrasound method of anterior chamber depth measurement (area under the curve, 0.93 and 0.90, respectively; z test, P = .001). Handheld ultrasound (area under the curve, 0.86) was inferior to optical measurement (z test, P = .001) but did not differ significantly from slitlamp ultrasound (z test, P = .06). The optical method gave sensitivity of 85% and specificity of 84% at a screening cutoff of less than 2.22 mm for detecting occludable angles. CONCLUSIONS: Measurement of axial anterior chamber depth can detect occludable angles in this Asian population and therefore may have a role in population screening for primary angle-closure glaucoma.

Detection of gonioscopically occludable angles and primary angle closure glaucoma by estimation of limbal chamber depth in Asians: modified grading scheme.

AIM: To evaluate the performance of limbal chamber depth estimation as a means of detecting occludable drainage angles and primary angle closure, with or without glaucoma, in an east Asian population, and determine whether an augmented grading scheme would enhance test performance. METHOD: A two phase, cross sectional, community based study was conducted on rural and urban areas of Hövsgöl and Omnögobi provinces, Mongolia. 1800 subjects aged 40 to 93 years were selected and 1717 (95%) of these were examined. Depth of the anterior chamber at the temporal limbus was graded as a percentage fraction of peripheral corneal thickness. An "occludable" angle was one in which the trabecular meshwork was seen in less than 90 degrees of the angle circumference by gonioscopy. Primary angle closure (PAC) was diagnosed in subjects with an occludable angle and either raised pressure or peripheral anterior synechiae. PAC with glaucoma (PACG) was diagnosed in cases with an occludable angle combined with glaucomatous optic neuropathy and consistent visual morbidity. RESULTS: Occludable angles were identified in 140 subjects, 28 of these had PACG. The 15% grade (equivalent to the traditional "grade 1") yielded sensitivity and specificity of 84% and 86% respectively for the detection of occludable angles. The 5% grade gave sensitivity of 91% and specificity of 93% for the detection of PACG. The interobserver agreement for this augmented grading scheme was good (weighted kappa 0.76). CONCLUSIONS: The traditional limbal chamber depth grading scheme offers good performance for detecting occludable drainage angles in this population. The augmented scheme gives enhanced performance in detection of established PACG. The augmented scheme has potential for good interobserver agreement.

Outcome of 1000 consecutive clinic- and hospital-based cataract surgeries in a Danish county.

PURPOSE: To evaluate the homogeneity and quality of cataract surgery in a Danish county. SETTING: Four private eye clinics and the Department of Ophthalmology, Hillerød Hospital, Frederiksborg County, Denmark. METHODS: This prospective study comprised 1012 consecutive cases of age-related cataract; 48% of the surgeries were performed in the hospital and 52%, at 1 of 4 clinics. Demographic and clinical data were recorded on standardized data sheets at referral, surgery, and final refraction. Main outcome measures were change in best corrected visual acuity (BCVA), refractive power at final refraction, surgery-related complications, and waiting time for surgery and final refraction. RESULTS: The hospital group had greater dispersion of age (P < .001) and higher frequency of general health problems (P < .005) and glaucoma (P < .01) than the clinic group. Fifty-four percent of surgeries were by phacoemulsification and 46%, by extracapsular cataract extraction (ECCE). In general, phacoemulsification was prevalent at the hospital and ECCE at the clinics. No difference was found between groups in visual acuity at final refraction. Of all patients, 87.1% attained a BCVA of 0.5 or better and of the best cases, 96.2%. Zonule or capsule rupture with or without vitreous loss occurred more often in the hospital group (P < .05), while the incidence of postoperative complications was identical in the 2 groups. One cases of retinal detachment was found. Time from referral to final refraction was shorter at clinics, while waiting time from surgery to final refraction was shorter at the hospital (P < .001). CONCLUSION: Dividing cataract surgery between hospital and private clinics seems to be a satisfactory model for meeting the increasing demand for cataract surgery.

Central corneal thickness and intraocular pressure in a Mongolian population.

OBJECTIVE: The purpose of the study was to quantify the variation of central corneal thickness (CCT) in an east Asian population and to examine its relationship to estimates of intraocular pressure (IOP) made with an applanation tonometer. DESIGN: The study design was a cross-sectional, population-based survey. PARTICIPANTS: One thousand two-hundred forty-two residents of Hövsgöl Province, Mongolia, 10 to 87 years of age participated. MAIN OUTCOME MEASURES: The CCT was measured using an optical pachymeter in all subjects. The IOP was measured using a, Goldmann-type applanation tonometer in subjects 40 years of age and older. RESULTS: There was a highly significant decrease in CCT with age: 5 microns/decade in men and 6 microns/decade in women (both, P < 0.0001). A highly significant positive correlation was identified between IOP and CCT. Linear regression analysis suggests that between the ages of 40 and 80 years, an increase in CCT of 10 microns is associated with an increase in IOP measurements of 0.18 mmHg in right eyes (95% confidence interval, 0.12-0.25) and 0.24 mmHg in left eyes (95% confidence interval, 0.17-0.31). The authors calculate that interindividual differences in CCT may produce a difference in measured IOP of between 2.3 and 3.1 mmHg. CONCLUSIONS: Variation in CCT is a significant source of variation in IOP measurements between individuals. The authors suggest that measurement of corneal thickness should be considered when assessing IOP as a risk factor for glaucoma in east Asians.

Anterior chamber depth in Mongolians: variation with age, sex, and method of measurement.

PURPOSE: To document anterior chamber depth in a Mongolian population and quantify the variation in this parameter attributable to age, sex, and method of measurement. METHOD: Depth of the anterior chamber was measured by optical pachymetry in 1,242 subjects aged 10 to 87 years. Figures for "true" anterior chamber depth were calculated by subtracting central corneal thickness from the distance between the anterior corneal epithelium and anterior lens capsule. A-mode ultrasound was also used to measure the distance from anterior corneal epithelium to anterior lens capsule in 94% (942) of subjects aged 40 years and older. These ultrasound data were compared with measurements of the same distance obtained by optical pachymetry. RESULTS: Mean anterior chamber depth in women was more shallow than in men of all ages (ANOVA, P < .0001), although this difference varied according to age. Mean anterior chamber depth decreased with age and was most accurately represented by a cubic function of age. This change was maximal between the ages of 30 and 60 years and equaled 0.15 mm per decade in men and 0.21 mm per decade in women. Mean depth of the anterior chamber measured by ultrasound was significantly less than the equivalent optical measurement (difference of 0.14 mm in right eyes, P < .001). CONCLUSIONS: Mean anterior chamber depth in Mongolians decreases with age and is more shallow in women than in men. Ultrasound and optical methods of anterior chamber depth measurement yield significantly different results and are therefore not directly comparable.

Glaucoma in Mongolia. A population-based survey in Hövsgöl province, northern Mongolia.

OBJECTIVES: To determine the prevalence of glaucoma and suspect glaucoma, and to classify the cases detected according to mechanism. DESIGN: A population-based prevalence study. SETTING: Rural and urban locations in Hövsgöl province, northern Mongolia. PARTICIPANTS: Nine hundred forty-two (94.2%) of 1000 individuals 40 years of age and older were examined. MAIN OUTCOME MEASURE: Primary angle-closure glaucoma was diagnosed in subjects with previous acute or intermittent symptoms of angle closure and in individuals with an occludable angle and an intraocular pressure greater than 19 mm Hg or a glaucomatous visual field. RESULTS: The prevalence of manifest primary angle-closure glaucoma was 1.4% (14 subjects). The prevalence of gonioscopically occludable angles was 6.4% (64 subjects, including those with glaucoma). Primary open-angle glaucoma was diagnosed in 5 subjects (prevalence, 0.5%). As all these subjects were older than 60 years, the prevalence became 2.1% for this age group. Three cases (prevalence, 0.3%) of secondary open-angle glaucoma were detected. No cases of secondary angle-closure glaucoma were diagnosed. The prevalence of blindness was 1.2% (12 subjects), and primary glaucoma accounted for one third of these cases (4 subjects). CONCLUSIONS: We confirmed glaucoma as a major public health problem in northern Mongolia. Primary angle-closure glaucoma is more prevalent than primary open-angle glaucoma, supporting clinic-based data from other east Asian countries. Among the subjects examined, 97 (9.7%) had either manifest, latent, or suspect glaucoma. Neighboring populations may be similarly affected owing to a shared genetic heritage.

[Anatomical risk factors of angle-closure glaucoma. A 10-year study of limbal and axial anterior chamber depths in a risk population]. / Anatomiske risikofaktorer for vinkellukningsglaukom. Et tiårsstude over betydningen af lav limbal og aksial kammerdybde i en risikobefolkning.

The present follow up study was undertaken in order to evaluate the predictive value of a low limbal chamber depth (LCD) and axial anterior chamber depth (ACD) over ten years. A population of 539 Greenlanders had been examined in 1979, using LCD estimations and ACD re-measurements by Haag Streit slit lamp pachymetry. ACD had also been measured in the same population 1969. Persons above age 40 in 1989, who were without glaucoma in 1979 and had shown an LCD value < or = 0.25 of corneal thickness (= CT), and an ACD value of < or = 2.70 mm (CT included) were selected as probands. A total of 75 such persons (= 84% of those alive and eligible) were examined in 1989. Five had developed PACG during the ten year period. At the survey seven more PACG cases were detected, yielding a PACG prevalence of 12/75 = 16%. LCD and ACD did not show significant association with eventual PACG status within the sample while gonioscopical status did so (p < 0.02). Creeping, synechial angle-closure was frequent. Among probands not examined, mostly due to death, 5/54 had developed PACG during the ten year period. Non-probands had their records scrutinized for PACG; yet among the 258 persons above age 40 no PACG case was found. Thus a fairly simple, anatomical slit lamp evaluation/measurement of limbal and axial anterior chamber depths was found to effectively select a subgroup which over ten years proved to be at risk of PACG-development.

Anatomical risk factors in primary angle-closure glaucoma. A ten year follow up survey based on limbal and axial anterior chamber depths in a high risk population.

A population of 539 persons was examined in 1979, using LCD and ACD estimations acc. to van Herick et al. and by Haag Streit pachymetry, respectively. ACD had been measured already in 1969, due to a remarkable occurrence of primary angle-closure glaucoma (PACG) in the survey population of Greenland Eskimos (District of Uummannaq). The present follow up study in 1989 aimed at persons presently above age 40, who had shown either an LCD value graded as 0 (contact) or 1 (< 0.25 of corneal thickness = CT), or a value of 2 (= 0.25 CT) if an ACD value of < = 2.70 mm (CT included) had also been found. PACG patients or suspects known in 1979 already were excluded from the present analyses. A total of 75 persons was now examined. Five had developed acute (n = 2) or intermittent PACG (n = 3) during the ten year period. At the survey 3 intermittent and 4 latent PACG cases were detected, yielding in ten years a PACG prevalence of 12/75 = 16% (sex ratio: M/F = 2/10). One male case of severe secondary (partly inflammatory) ACG was also found. Past and present LCD and ACD values are given as well as gonioscopical status. Creeping, synechial angle-closure was frequent. Among probands who could not be examined, mostly due to death before 1989, 5/54 had developed PACG during the ten year period. Non-probands according to above criteria were mostly not examined. Yet their records were scrutinized for any event suspect of PACG. Thus among 258 persons above age 40 no PACG case was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary angle-closure glaucoma and mononuclear blindness. Clinical pattern in 2 Inuit women from Greenland.

Primary angle-closure glaucoma (PACG) occurs in various clinical forms and is a permanent challenge for medical personnel responsible for eye care in elderly persons, for medical officers in the Arctic in particular. A clinical report is given of two cases: one with a destructive attack of classical acute glaucoma in a 46 year old woman versus another with a totally symptomless, gradual monocular blindness in a woman, aged 56. In both patients the fellow eye showed incipient chamber angle synechia formation. Peripheral iridectomy has given fully normal fellow eye function in the first woman, now for 22 years. The other had a recent YAG laser iridotomy in her fellow eye. The patients are described on the background of PACG population studies performed in Greenland since the 1960'ies, including gonioscopy and extensive anterior chamber depth measurements as attempts of early PACG detection.

[Eye care in Greenland in 1979-1988]. / Ojenlaegearbejdet i Grønland 1979-1988.

Specialist eye care in Greenland is described on the basis of 66 reports from all 30 visiting consultants during a ten-year period. During this time the durations of the visits increased to approximately seven months per year for 8-9 ophthalmologists who undertook approximately 2,500 consultations annually. The diagnoses were distributed as follows: 30% anomalies of refraction, 15% cataract, 12% conditions in the posterior segment and 10% glaucoma, i.e. a considerable proportion of eye diseases associated with advancing age and with a particular Greenlandic influence. The workload was particularly great and averaged more than a reasonable weekly load despite the increase in number of days of employment. Until 1985-1986, eye surgery activities showed a considerable increase after which operative interventions for cataract and glaucoma were mainly referred to Rigshospitalet. The great increase in the number of referrals is discussed in relation to the marked changes in the therapeutic possibilities for cataract and glaucoma: extracapsular cataract extraction with posterior chamber implantation using an operation microscope and YAG-laser iridectomy of early angle closure glaucoma. The requirement of an eye surgical unit in Greenland appears to be pressing together with continuation of specialist eye care in the districts.

Early detection of primary angle-closure glaucoma. Limbal and axial chamber depth screening in a high risk population (Greenland Eskimos).

In an unselected population of 541 Greenland Eskimos, a survey was performed aiming at early primary angle-closure glaucoma (PACG) detection. Of the men 162/274 and women 182/267 were above the age of 40. The ophthalmological examination included slit-lamp grading of limbal chamber depth (LCD), axial Haag Streit pachymetric chamber depth (ACD) measurement and direct gonioscopy in all shallow chamber cases. Dark room prone position provocative tests were extensively used in suspects. In 3 men and 5 women PACG was diagnosed, giving, above age 40, a prevalence of 2% in men (3/162) and increasing the PACG prevalence to 10% in women (18/182) as 13 were known a priori. PACG suspects, needing prophylactical iridectomy or pilocarpine, constituted 1 man and 6 women. Furthermore, narrow angles were found in 14 men and 27 women above age 40, and so far untreated. On the present background of highly effective surgical and YAG-laser iridectomy facilities in early PACG, local, other arctic and global prevention of blindness aspects are briefly discussed, with a special outlook to SE-Asia.

Intraocular lens calculation. An evaluation of Binkhorst and SRK estimates in 100 consecutive cataract extractions with 3M type 78 anterior chamber lens implantation.

Intraocular lens power prediction and final astigmatism were evaluated in 100 consecutive cataract patients (age 57-92 years, mainly with intracapsular extraction) 4-13 months after insertion of a 3M type 78 anterior chamber lens. The analysis was based on refractive recordings from the referring ophthalmologists who took care of post-operative controls. Ninety-two patients were accepted for the study. A Sonometrics DBR 400 ultrasound equipment and a Haag-Streit keratometer had been used for measuring eye length and corneal power, the Binkhorst programme and SRK formula for selecting IOL power, resulting in an IOL range of +12 to +23 D. Mainly, low myopia was intended. Nearly 50% fell within 0.5 D from predicted value; 90% were within +/- 1.5 D, by both calculating methods. SRK predictions appeared unaffected by eye size, while axial length (x) significantly influenced Binkhorst prediction (y): y = 8.08-0.35x (r = -0.40), the deviation being most marked in very short eyes. For eyes of midsize the two methods did not differ. Regarding astigmatism, 3 patients ended with values above 3D. In 83% it was less than 2D. Eighty per cent obtained a visual acuity of 0.5 or better. All things considered we feel that the calculation procedure should be standard when performing cataract surgery with IOL implantation.

Limbal and axial chamber depth variations. A population study in Eskimos.

In an unselected population sample of 505 adult Greenland Eskimos limbal chamber depth (LCD) was estimated according to van Herick et al. (1969), and axial chamber depth (ACD) was measured optically using Haag Streit pachymetry. For comparison LCD was estimated in 308 Danes above 40 years. A marked naso-temporal asymmetry in LCD scoring was found indicating a shallower chamber at the temporal limbus. No corresponding gonioscopic asymmetry was observed. Significant age, sex, and ethnic variations were demonstrated, the lower levels of both parameters being found in elderly persons, women and Eskimos, respectively. Danes showed a lower level of LCD scores than reported in Americans. In detection of eyes showing shallow chambers in the Eskimo population (arbitrarily: ACD less than or equal to 2.0 mm) the van Herick slit-lamp test at temporal limbus yielded a sensitivity of 91%, a specificity of 53% and predictive values of a positive and a negative test of 30% and 96%, respectively. At gonioscopy narrow angles were often found among eyes showing LCD less than or equal to 1/4 of corneal thickness, even when ACD was greater than 2.0 mm (in 25%).

Localized scleroderma 'en coup de sabre' and iridopalpebral atrophy at the same line.

A case is reported of scleroderma 'en coup de sabre' in a 13-year-old girl with atrophy of the nasal part of the iris and loss of cilia on the upper eyelid. The lesions of the front and eye were located on precisely the same line. The line did not follow the innervation fields of the cranial, peripheral or autonomous nerves. Nor did it follow the tension lines of the skin (Langer), or underlying anatomical structures. It is discussed that the predisposition to the 'coup de sabre' line seen in localized scleroderma was laid down in the mesenchyme in early foetal life before the differentiation of the anatomical structures.

Anterior chamber depth, genes and environment. A population study among long-term Greenland Eskimo immigrants in Copenhagen.

Previous population studies have demonstrated a shallow anterior chamber as an inherited characteristic of Eskimos, explaining their high prevalence of primary angle-closure glaucoma. In order to evaluate the stability of the anterior chamber depth (ACD) distribution and its inherent morbidity risk in a different environment, immigrant Greenland Eskimo women in Copenhagen, aged 40 years or more were sampled. Those who had been at least 25 years in Denmark were examined (N = 64), using Haag Streit pachymetry, limbal chamber depth (LCD) estimation and gonioscopy. The ACD level of the immigrants was significantly higher than that of their background population, in ethnically 'mixed' as well as 'pure' subgroups, and correspondingly the LCD grading was higher among the immigrants. Primary angle-closure glaucoma was found in 3%. The refraction showed no significant trend towards myopia compared with native Greenland Eskimos. Environmental factors influencing ACD, e.g. through the rate of biological ageing, seem to exist, but their nature is unknown.