Ability of non-ophthalmologist doctors to detect eyes with occludable angles using the flashlight test

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  • ORIGINAL PAPER

    Ability of non-ophthalmologist doctors to detect eyeswith occludable angles using the flashlight test

    Carolina Pelegrini Barbosa Gracitelli Bruno Landgren

    Flavia Bracale Graciani Aline Katia Siqueira Sousa

    Augusto Paranhos Jr. Tiago Santos Prata

    Received: 29 March 2013 / Accepted: 14 September 2013 / Published online: 1 October 2013

    Springer Science+Business Media Dordrecht 2013

    Abstract The aim of this study is to assess the ability

    of non-ophthalmologist doctors to detect eyes with

    occludable angles using the flashlight test (FLT). For

    this study, a total of 45 patients were prospectively

    enrolled. After an ophthalmological examination all

    patients underwent FLT by two non-ophthalmologist

    examiners in a masked and standardized fashion. Two

    gynecologists were chosen, as they often deal with

    patients exposed to drugs that can trigger pupillary

    block. An occludable angle was defined as C2

    quadrants in which the posterior trabecular meshwork

    was not visible by gonioscopy without indentation

    (performed by an experienced glaucoma specialist).

    Whenever both eyes were eligible, one was randomly

    selected for analysis. Sensitivity and specificity for

    detection of occludable angles were generated, and the

    agreement between examiners was assessed. This

    study results showed that the mean age was

    47.1 16.4 years and most patients were female

    (67.7 %). There was a good agreement between

    observers for FLT results (j = 0.77; p = 0.04).

    Similar values of sensitivity and specificity were

    found for both examiners (92 and 67 % vs 97 and

    67 %, respectively). Based on the findings of this

    study, it was concluded that FLT showed good

    sensitivity for detection of eyes with occludable

    angles. The fact that it can be easily and reliably

    performed by non-ophthalmologist highlights its use

    as a screening tool in patients requiring medications

    that can induce angle closure.

    Keywords Anterior chamber depth Occludable angle Screening method Anticholinergic drugs

    Introduction

    Recent estimates show that more than 67 million

    people in the world have glaucoma. Although open-

    angle glaucoma comprises approximately two-thirds

    of these cases, angle-closure glaucoma is responsible

    for half of those who are blind from the disease [1, 2].

    In addition, in populations such as Chinese, Indian and

    Mongolian, its prevalence is equal or even greater than

    that of open-angle glaucoma [1, 37].

    Primary angle-closure glaucoma (PACG) results

    from a combination of predisposing anterior segment

    anatomy and unfavorable physiological behavior [2].

    Currently, it is defined as an occludable angle

    C. P. B. Gracitelli (&) B. Landgren A. K. S. Sousa A. Paranhos Jr. T. S. PrataOphthalmology Department, Federal University of Sao

    Paulo, Rua Botucatu, 821 Vila Clementino,

    04023-062 Sao Paulo, Brazil

    e-mail: carolepm@gmail.com

    F. B. Graciani

    Gynecology Department, Federal University of Sao Paulo,

    Sao Paulo, Brazil

    123

    Int Ophthalmol (2014) 34:557561

    DOI 10.1007/s10792-013-9856-x

  • associated with trabecular meshwork damage/dys-

    function (typically raised intraocular pressure [IOP] or

    presence of peripheral anterior synechiae) and struc-

    tural and/or functional evidence of glaucomatous optic

    neuropathy [8]. Although less common than the

    chronic form, the subacute and acute forms of angle

    closure may be the first manifestation of the disease.

    Reported anatomical risk factors for PACG include

    short axial length, shallow anterior chamber (AC),

    thick and relatively anterior-positioned lens, and small

    corneal diameter and steep curvature [912]. Although

    an occludable angle can be promptly identified by

    indentation gonioscopy, the examination is technically

    difficult for non-glaucoma specialists and is not

    appropriate for large-scale screening [13, 14].

    Different types of systemic medications may trigger

    an acute attack in eyes with predisposing anterior

    segment anatomy [1517]. On daily practice, non-

    ophthalmologist doctors, such as gynecologists, usually

    prescribe these drugs without a preventive AC angle

    assessment. This situation highlights the importance of

    investigating a straightforward screening method to aid

    clinicians in identifying individuals at risk [18].

    The flashlight test (FLT) is a simple light-based

    method which has been previously described for AC

    depth evaluation [19]. This technique has been used in

    population-based studies and was found to be a good

    screening tool [2022]. In this study, we aimed to

    investigate the ability of non-ophthalmologist doctors

    to identify eyes at risk (those with occludable angles

    based on gonioscopic examination) using the FLT.

    Materials and methods

    This cross-sectional study adhered to the tenets of the

    Declaration of Helsinki and was approved by the

    Institutional Review Board of the Federal University

    of Sao Paulo. In addition, written informed consent

    was obtained from all participants.

    Patients

    We prospectively enrolled patients with glaucoma and

    glaucoma suspects, attending our outpatient clinic. All

    patients underwent a complete ophthalmological

    examination. Key exclusion criteria were conditions

    precluding clear visualization of the AC (e.g., ptery-

    gium, corneal opacity), congenital anterior segment

    abnormalities, eyelid alterations, ocular trauma and

    intraocular surgery (incisional or laser procedures).

    After inclusion, each patient underwent the FLT,

    performed by two different gynecologists, in separate

    rooms. The eye to be examined was randomly chosen

    on the toss of a coin. The test was performed using a

    Maglite Cell 2D torch. A flashlight beam was directed

    parallel to the iris from the temporal side as originally

    reported by Vargas et al. [19]. Eyes identified as

    having a narrow AC were those in which a nasal iris

    shadow, formed between the limbus and the pupillary

    edge, was visualized. Conversely, eyes identified as

    having a deep chamber were those in which a nasal

    light reflex, formed between the limbus and the

    pupillary edge, was visualized. Immediately after the

    FLT, patients underwent gonioscopic examination

    (Sussmann four-mirror lens) by a glaucoma specialist

    (TSP) in a masked fashion. Gonioscopy was per-

    formed in a dark room using a Zeiss SL130 slit-lamp

    with the minimum intensity of illumination compat-

    ible with good visualization. The slit-beam was

    shortened so that it did not fall on the pupil. Angles

    were graded as occludable (posterior trabecular

    meshwork not visible in C2 quadrants without inden-

    tation) or nonoccludable.

    Statistical analysis

    Descriptive analysis was used to present demographic

    and clinical data. Agreement between the two non-

    ophthalmologist examiners (gynecologists) and the

    glaucoma specialist was determined using the

    weighted Kappa (j) statistic. A j value of 00.2suggests poor agreement, 0.20.6 fair, 0.60.8 sub-

    stantial, 0.81.0 represents almost perfect agreement,

    and[0.75 is usually considered good agreement [23].Values of sensitivity and specificity were also gener-

    ated, considering the gonioscopic grading of the angle

    as the gold standard.

    Results

    A total of 45 patients were included. The mean age of

    study patients was 47.1 16.4 years (range

    1985 years) and the majority of patients were female

    (67.7 %). The percentage of eyes identified as having

    a narrow AC by the FLT was 20 % for the first

    observer and 18 % for the second observer (n = 9 and

    558 Int Ophthalmol (2014) 34:557561

    123

  • 8, respectively). The prevalence of occludable angles

    according to gonioscopy was 20 % (n = 9).

    The j value was 0.77 (p = 0.04), showing goodagreement between the two gynecologists. Similar

    values of sensitivity and specificity were found for the

    two examiners (92 and 67 % vs 97 and 67 %,

    respectively (Table 1). Regarding the cases in which

    there was no agreement between gonioscopy and FLT

    grading, three eyes with occludable angles were

    classified as having deep ACs while three eyes with

    nonoccludable angles were classified as having narrow

    ACs by the first observer. For the second observer, two

    eyes with occludable angles were classified as having

    deep ACs while one eye with a nonoccludable angle

    was classified as having a narrow AC.

    Examples of eyes with occludable and nonocclud-

    able angles, correctly identified by the FLT, are given

    in Figs. 1 and 2, respectively.

    Discussion

    Patients are often treated by non-ophthalmologist

    doctors with systemic medications that can trigger an

    acute angle-closure attack in anatomically predis-

    posed eyes [19, 24]. Although a glaucoma specialist

    can identify those at risk before such medications are

    prescribed, this type of specific evaluation is not

    always available, and probably not feasible in daily

    practice. Gonioscopy itself requires specific training

    and cannot be performed by a general clinician [19,

    24]. These facts emphasize the need for a reliable and

    sensitive screening method. In the present study, we

    demonstrated the FLT as a useful tool for identifica-

    tion of eyes at risk (with occludable angles) by non-

    ophthalmologist doctors.

    There is scant information in the literature about the

    use of the FLT as a screening method. In most of the

    available studies, although non-trained clinicians were

    not evaluated as examiners, good sensitivity values

    were found [19, 21, 25]. In our study, investigating the

    applicability of the test when performed by two

    gynecologists, FLT also had good sensitivity (92 %

    for the first observer and 97 % for the second

    observer), which is in agreement with previously

    published data [21, 22]. In contrast with the majority

    of publications, one study from the south of India

    reported very low sensitivity (45 %) using the same

    technique [26]. One possible reason for the differences

    of reported sensitivity values between studies could be

    the variability of anterior segment anatomy in some

    populations that could influence the type of angle-

    closure mechanism, affecting the efficacy of the FLT

    [24]. Van Herick et al. [27] pointed out that the

    flashlight method might be subject to misclassification

    in eyes with either plateau iris configuration or with

    central shallowing of the AC but wide drainage angles.

    Table 1 Sensitivity and specificity values for the flashlighttest (two examiners)

    Observer 1 (%) Observer 2 (%)

    Sensitivity 92 97

    Specificity 67 67

    Considering the gonioscopic grading of the angle as the gold

    standard

    Fig. 1 Eye with a nonoccludable angle correctly identified bythe flashlight test

    Fig. 2 Eye with an occludable angle correctly identified by theflashlight test

    Int Ophthalmol (2014) 34:557561 559

    123

  • The main clinical implication of our findings is that

    the FLT could be used by general doctors to identify

    patients at risk for angle closure before prescribing

    some medications. In any medical field, an ideal

    screening test should have high sensitivity. Although it

    would possibly lead to a significant number of false

    positive test results, the majority of the patients at risk

    could be detected and referenced to a more specific

    ophthalmological evaluation [25]. The fact that we

    found sensitivity values[90 %, independently of theobserver, confirms the FLT as a relevant screening

    tool.

    In the context of our study, it is important to discuss

    the most common medications that could trigger an

    acute glaucoma attack. They include topical mydria-

    tics, anticholinergic drugs, adrenergic agents, drugs

    for upper respiratory infections, antidepressants, anti-

    convulsants, sulfamate derivative, antihistamines and

    cabergoline [28]. These drugs when prescribed for a

    patient with an anatomically predisposed eye may

    result in high intraocular pressure, reduction in visual

    acuity, glaucomatous optic neuropathy, visual field

    loss and blindness [29, 30].

    Looking carefully at the characteristics of patients

    that develop an acute glaucoma attack, one should be

    careful with elderly women when prescribing any of

    the above cited medications. There is a predominance

    of female patients with pupillary block, which is

    probably caused by a shallower AC observed in these

    eyes [3134]. In our sample, the majority of patients

    were female (67.7 %). Another risk factor is age. The

    prevalence of papillary block and PACG also

    increases with age. The depth and volume of the AC

    diminish, which may result from a thickening and

    forward displacement of the lens [35]. In this study the

    mean age of patients was 47.1 16.4 years, which is

    not considered an elderly population.

    Some specific characteristics of our study should be

    considered. First, our study is limited by its small

    sample size and low prevalence of narrow angles,

    which probably reflects the prevalence of narrow

    angles in Brazil. Second, some studies have compared

    FLT with Van Herick test as a screening test [26]. We

    have chosen not to make a comparison with Van

    Hericks method because our focus was to investigate

    non-ophthalmologist doctors as observers.

    In summary, the FLT showed good sensitivity to

    detect eyes with occludable angles. The fact that

    it can be easily and reliably performed by non-

    ophthalmologist doctors highlights its use as a

    screening tool in patients requiring medications that

    can induce angle closure.

    Conflict of interest The authors have no conflict of interestregarding the present study.

    Funding None.

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