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ORIGINAL ARTICLE
Year : 2015  |  Volume : 28  |  Issue : 1  |  Page : 174-180

Resurrection of the Amsler chart in macular diseases


1 Department of Opthalomology, Faculty of Medicine, Menoufia University, Menufia, Egypt
2 Department of Ophthalmology, Faculty of Medicine, Fayoum University, Fayoum Governorate, Egypt

Date of Submission05-Dec-2014
Date of Acceptance12-Jul-2014
Date of Web Publication29-Apr-2015

Correspondence Address:
Mostafa Mohammed M Diab
Department of Ophthalmology, Faculty of Medicine, Fayoum University, 35 Ahmed Mortada Street, Al mesallah - Fayoum Governorate
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.155983

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  Abstract 

Objectives
To assess the validity of the Amsler chart as a screening test for the detection of macular diseases and to test its reliability in the follow-up of patients with macular diseases compared with other confirmatory investigative methods such as fundus fluorescein angiography (FFA) and optical coherence tomography (OCT).
Background
The Amsler chart provides a convenient method to detect and monitor macular diseases on the basis of a grid pattern that allows both scotomas (detected by missing or blurred lines) and metamorphopsia (bowed or distorted lines) to be detected. Since its discovery, the Amsler grid has become important in the evaluation of the central 20° of the visual field surrounding the fixation.
Methods
A total of 50 eyes of 50 patients with different types of macular diseases were tested by the Amsler chart and compared with other diagnostic investigations (fundus fluorescein angiography and optical coherence tomography) in each patient. These patients were followed at 1, 3, and 6 months by BCVA, the Amsler chart, and other investigations.
Results
Fifty patients (50 eyes) were analyzed statistically. The sensitivity of detection of macular disease by the Amsler grid was 88% (95% confidence interval: 77.9-97.6%). There was substantial agreement between the results of the Amsler grid and those of other investigations on the follow-up evaluation.
Conclusion
The Amsler chart is an accurate test in detecting macular disease, and if used properly, it could be effective in the early detection of macular diseases. The Amsler chart could be used for the follow-up of patients suffering from macular diseases with high reliability.

Keywords: Amsler chart, macula, metamorphopsia, scotoma


How to cite this article:
Nassar MK, Badawi NM, Diab MM. Resurrection of the Amsler chart in macular diseases. Menoufia Med J 2015;28:174-80

How to cite this URL:
Nassar MK, Badawi NM, Diab MM. Resurrection of the Amsler chart in macular diseases. Menoufia Med J [serial online] 2015 [cited 2018 Jul 16];28:174-80. Available from: http://www.mmj.eg.net/text.asp?2015/28/1/174/155983


  Introduction Top


Qualitative disturbances of vision such as distortion and relative scotomas that accompany different macular diseases can escape ordinary quantitative methods of examining central visual acuity. The patient may have 6/6 central vision, but the quality of vision might be missing. This is related to the fact that no more than 44% of the foveolar neuroretinal channels are required to have 6/6 vision. Thus, 6/6 vision is not a proof of having no pathology [1]. This functional disturbance usually precedes an evident organic lesion and is a sensitive guide to the course of any macular disease. The problem is how to find out these qualitative changes of vision and how to help patients explain, analyze, and document their observations [2]. At the same time, early detection of the onset or the progression of macular diseases is likely to become increasingly important as new modalities of treatment are introduced. The Amsler chart can detect and localize these qualitative defects in different macular diseases exactly and precisely [2]. There are other sophisticated diagnostic investigations such as fundus fluorescein angiography (FFA) and optical coherence tomography (OCT). Despite their high accuracy and their essential role in the diagnosis of macular lesions, FFA and OCT have limitations in their use. Fluorescein angiography is not a procedure without side effects. OCT is an expensive investigation and not available all the time. In contrast, the Amsler chart is a simple, inexpensive, and available test that can easily detect different macular lesions and precisely enable the patient to analyze changes of Amsler grid abnormalities (size, shape, density, and location); thus, we can follow the progress of the macular disease over time as frequently as we need without side effects and without expenditure.

The Amsler grid was initially introduced in 1947 as a method for the clinical evaluation of patients with macular diseases, but the idea to use a regular pattern of lines to map scotomas or demonstrate metamorphopsia is actually very old and has been in the literature for centuries. The Scottish philosopher Thomas Reid (1710-1796) may have been the first to write about metamorphopsia. Thomas Reid described distortion of his vision in 1764 after an episode of sun gazing, and recognized that the problem was probably of retinal origin [3]. In 1862, Richard Föster (1825-1902), a self-taught ophthalmologist in Breslau, Germany, published what may be the first medical illustration of metamorphopsia, showing distortion in a square grid of lines [Figure 1].
Figure 1: Illustration of the metamorphopsia published by Förster in 1862 [3] .

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The conventional grid is a 10 cm square subdivided every 5 mm by vertical and horizontal parallel lines, thus giving the appearance of a perfectly regular grid [Figure 2] [5].
Figure 2: Chart No. 1 (the conventional Amsler grid) [4] .

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The image of the Amsler grid occupies only a small central area of 10° of the visual field. When projected on to the fundus, always at a distance of 28-30 cm, it occupies a greater area than the macula and fovea, covering 28.73 sqmm [Figure 3] [4],[7].
Figure 3: The grid superimposed on the retina [6] .

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The objective of this study was to test the sensitivity of the original Amsler grid in the detection of different macular diseases and to assess its reliability in following up these patients.


  Participants and methods Top


This study was carried out in the Ophthalmology Department of the Menoufia University (Sheben El-kom, Menoufia, Egypt) between November, 2010 and March, 2014. The protocol was previously approved by the Ethics Committee of this institution and followed the tents of Declaration of Helsinki. All of the patients included in the study read the informed consent by themselves. This prospective noncomparative interventional study included a total number of 50 eyes of 50 patients, suspicious for macular lesion, and with presumed physical and mental aptitude [Table 1].

Of them, 26 patients were women and 24 were men. Complete ophthalmic examination of each patient was performed. Patients with dense media opacity that impeded biomicroscopic evaluation of the macula or that impeded the carrying out of fundus photography, patients with BCVA less than 6/60, those who were previously diagnosed with macular disease, and those who had a central field defect due to diseases other than macula were excluded.
Table 1: Demographics of patients and participants included in this study

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The Amsler grid was given to the patients included in the study with precise instructions about its use. The chart is used at a distance of 28-30 cm, with the patient wearing his near correction, if indicated. The chart must be clearly and evenly lighted as for a reading test. All patients were tested with undilated reactive pupils [4,7]. The patient was directed to fixate upon the dot in the center of the grid during the whole time of examination and to just be aware of the surrounding area rather than looking all around [8]. Each eye is examined at a time and six questions in a logical order are asked [Table 2].
Table 2: Questions presented during the Amsler grid test

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All observations of the patients were recorded on a separate chart printed in black on white paper. Other diagnostic investigations were performed according to each case (OCT, FFA, Humphrey visual field, etc). Then a plan of management was followed for every case according to the confirmed diagnosis. After receiving proper treatment, patients were followed by the Amsler chart, the best corrected visual acuity, and the above-mentioned confirmatory investigations at 1, 3, and 6 months.

Statistical analysis

The total sensitivity and specificity were calculated with their respective 95% confidence intervals (CIs) on the Amsler grid in the detection of macular disease. Agreement between the Amsler chart and other diagnostic methods (FFA, OCT, Humphrey visual field) on follow-up evaluation was tested by Cohen's k. A P less than 0.05 or a CI of 95% was considered significant. The SPSS software, version 11.0.1 (SPSS Inc., Chicago, Illinois, USA), was used for the statistical analysis.


  Results Top


Fifty patients (50.0 eyes) were analyzed statistically, after the criteria of inclusion/exclusion were applied. Of them, 26 (52%) were women. The mean age (±SD) was 47.94 years (±16.07) (range, 13-70 years). The detection sensitivity of the Amsler grid for macular disease among the studied patients was 87.2% (95% CI, 77.9-97.6%). In this study, the Amsler grid confirmed macular disease in 41 patients and predicted macular lesion in one patient who was confirmed to have macular disease 2 months later. It excluded macular lesion in one case with rheumatoid arthritis on antimalarial treatment, and excluded a membrane formation in a case of dry age-related macular degeneration (AMD). Amsler could not detect macular lesion in six patients compared with the diagnosis achieved by other types of investigations.

Out of the 16 diabetic patients, the Amsler chart could localize different lesions detected by the FFA and OCT in 12 patients only. Of the seven high-myopic eyes with suspected choroidal neovascular membranes (CNV) that were examined before we proceeded to more advanced investigations, central and paracentral metamorphopsia with sometimes relative scotoma were elicited by the Amsler in seven patients. Out of the seven patients, FFA showed a positive lesion in one case. On follow-up, the presumed normal case yielded positive data, previously predicted by the Amsler chart. The lesions in 18 patients with cystoid macular edema (CMO), retinal vein occlusion, and epimacular membrane were precisely drawn by the Amsler chart and confirmed by FFA and OCT [Figure 4]. Amsler grid distortion was noted in three of four patients with confirmed epimacular membrane.
Figure 4: (a) The Amsler recording chart on which a patient with postcataract cystoid macular edema has drawn shows central relative scotoma and metamorphopsia. (b) OCT of the same patient showing CME with CFT 881 μm and subfoveal neurosensory detachment. OCT, optical coherence tomography .

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Two patients under antimalarial treatment for more than 10 years were tested by the Amsler chart and automated visual field testing. One patient was found to have central and paracentral scotoma by both Amsler and automated visual field testing. The other case showed no abnormality by both techniques. Two patients with a suspicious macular hole were tested by the Amsler chart, which revealed central scotoma in one case and normal testing in the other case. OCT was performed for both cases, and revealed a full-thickness macular hole in the case with the central scotoma by Amsler and a lamellar macular hole in the case with normal Amsler chart testing. [Table 3] shows the abnormalities detected on Amsler grid testing by the 42 patients. One patient with AMD was tested with the Amsler chart, which revealed no abnormality. OCT and FFA were performed and showed no evidence of CNV. Two months later, the Amsler chart showed central relative scotoma and metamorphopsia. OCT and FFA revealed CNV [Figure 5].
Figure 5: The Amsler recording chart on which a patient wit h wet-AMD has drawn to show central relative scotoma and metamorphopsia. FFA of the same patient shows irregular leakage. OCT shows subfoveal active CNV. AMD, age-related macular degeneration; CNV, choroidal neovascular membranes; FFA, fundus fl uorescein angiography; OCT, optical coherence tomography .

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In the present study, Amsler grid testing matched with the results achieved by other types of investigations on follow-up evaluations [Figure 6]. On analyzing the results of Amsler grid testing and those of other investigations on follow-ups at 1, 3, and 6 months using Cohen's k, the result was as follows: at 1 month, there was excellent agreement (according to Fleiss) between the Amsler chart and other confirmatory investigations (k = 0.788 with P < 0.001); at 3 months, there was good agreement (according to Fleiss) between the Amsler chart and other confirmatory investigations (k = 0.672 with P < 0.001); at 6 months, there was excellent agreement (according to Fleiss) between the Amsler chart and other confirmatory investigations (k = 0.781 with P < 0.001).
Figure 6: Amsler grid results matched with other investigations (FFA, OCT, etc) in 45 patients (90%), 42 patients (84%), and 46 patients (92%) at 1, 3, and 6 months, respectively, and it was negative in 10, 12, and 4% of patients, respectively, whereas other investigations confi rmed the changes. FFA, fundus fluorescein angiography; OCT, optical coherence tomography .

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[Figure 6] illustrates Amsler recording charts and OCT of a 54-year-old female patient, diabetic and on oral treatment since 2 years, who presented to the clinic with blurred vision of the left eye 1 week ago. Her best corrected visual acuity was 6/6 (OD) and 6/12 (OS). Her symptoms were recorded using the Amsler grid (scattered central and paracentral relative scotomas and metamorphopsia) [Figure 7]a. Fundus biomicroscopy revealed blunt foveal reflex and scattered small hemorrhages. FFA was performed and it revealed old nonischemic CRVO and late leakage in the macular area. OCT revealed CMO with a central foveal thickness of 615 mm [Figure 7]b. She was treated by monthly intravitreal bevacizumab injections and followed by the Amsler grid, BCVA, and OCT. Three months later, there was marked improvement of the visual acuity to 6/6 corrected (OS), and OCT showed within the normal macula [Figure 7]d, but the patient was still complaining of blurred vision that appeared as paracentral scotoma on Amsler grid testing [Figure 6]c. On the follow-up 2 months later, BCVA decreased to 6/9, and Amsler grid testing revealed scattered paracentral scotomas [Figure 7]e. OCT was ordered and it showed recurrent CMO [Figure 7]f.

At the end of the study, the measured visual acuities
Figure 7: (a– f) Amsler grid drawings and OCT of a patient with CME due to nonischemic central retinal vein occlusion who was treated with monthly intravitreal bevacizumab injection. OCT, optical coherence tomography .

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ranged from 6/6 to 6/60, with 6/24 being the most frequent visual acuity measured. There was no apparent correlation between the visual acuity measured and the presence of Amsler grid abnormality at 6 months' visit. A total of 16 patients showed Amsler grid abnormality in the form of metamorphopsia, relative scotoma, and absolute scotoma despite achievement of good visual acuity (seven cases with macular edema of retinal vein occlusion, two cases with CNV, one case with diabetic macular edema, and one HCV positive case on INF therapy). Five patients had no abnormality by Amsler grid testing despite poor visual acuity. All the five patients had diabetic macular edema. [Figure 7] shows Amsler grid changes in a patient with right myopic CNV before and after 3 monthly intravitreal bevacizumab injections. At presentation, BCVA was 6/60, and Amsler grid testing revealed central relative scotoma and paracentral metamorphopsia. After treatment, the patient achieved good visual acuity 6/12, but was still complaining of distortion that recorded as parecentral metamorphopsia by Amsler grid ([Figure 8]a and b).{Figure 7}
Figure 8: (a, b) Amsler grid changes in a patient with right myopic CNV before (a) and after treatment (b). CNV, choroidal neovascular membranes .

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  Discussion Top


Early detection of the onset of macular disease is becoming increasingly important, especially with the introduction of new treatment modalities for macular diseases [5]. The Amsler chart can detect and localize these functional defects precisely in different macular diseases [2]. Despite their high accuracy and reproducibility, FFA and OCT have limitations in their use. Fluorescein angiography is not a procedure without side effects. OCT is an expensive investigation and not available all the time. In contrast, the Amsler chart is a simple, inexpensive, accurate tool and of a mass screening ability that easily detects different lesions. The Amsler chart has the benefit of being subjective, taking into consideration patients' symptoms.

In the present study, the Amsler chart detected macular disease in 41 of 49 patients confirmed to have macular disease by other advanced investigations. Using the Amsler chart, two patients were excluded as not having macular disease, and one case was predicted to have macular disease with a detection sensitivity of 87.2%. In the study by Nassar [2], the Amsler chart confirmed the diagnosis in 123 eyes and predicted the existence of a lesion in 20 eyes (six glaucoma suspects, two ocular hypertension, one optic amblyopia, two toxic amblyopia, two myopia, three rheumatoid, three with CME, and one with impending CRVO). Amsler grid testing corresponded with the diagnosis achieved by other types of investigations in 123 (86%) eyes and predicted the lesion ahead by 2-6 months in 20 (14%) eyes compared with other diagnostic investigative instruments. The results of the present study were nearly similar to that of Nassar's study, which investigated a larger number of patients and did not restrict the study to macular disease. The number of cases predicted to have a macular lesion with apparently normal fundus and normal fluorescein angiography was larger compared with our study. This can be explained by the better visual acuity (more than 6/24) of patients included in Nassar's study. Unlike this study, the patients in Nassar's study were not followed.

Klatt et al. [9] investigated the ability of the preferential hyperacuity perimeter and Amsler grid testing to detect metamorphopsia in retinal diseases of different origins in 147 patients (n = 153 eyes). The sensitivity of the Amsler grid in detecting metamorphopsia was 85% in patients with MH, CSR 73%, EM 100%, intermediate AMD 100%, classic CNV 94%, and occult CNV 71%.

In the study by Schuchard [10], the sensitivity of the Amsler chart has been shown to be as low as 56% when compared with the more accurate method of fundus microperimetry. In the study of Zaidi et al. [11], it was reported that 29 out of 100 new cases of CNV attended to in one institution had sought treatment after having perceived alterations in the examination with the original Amsler grid. All 100 patients had been instructed in previous consultations about the use of the Amsler grid for self-monitoring. Other authors [12] have shown that the sensitivity of the Amsler chart for the detection of AMD is 39% in wet AMD. From these data, it seems that a significant proportion of patients with macular disease will not be identified using the Amsler chart alone. First, these studies were restricted to patients with AMD. Second, whereas they examined the detection of scotoma, distortion may precede the development of scotoma in macular disease. Third, the different study design and analysis of the data do not permit direct comparison between the studies, but the performance of the examination under the orientation and observation of an examiner, with the asking of standard questions and constant observation of the fixation of the patient, may have been responsible for the greater sensitivity of the method in the detection of CNV. In only five out of 49 patients examined by Fine and colleagues, Amsler distortion was the first reported visual symptom, and yet under close supervision 44 of the 49 patients did report abnormality on the Amsler chart, suggesting noncompliance as another probable explanation for failure to detect an Amsler grid abnormality earlier [13].

In this study, the results of Amsler grid testing corresponded with those of other confirmatory investigations on the follow-up evaluation. Unfortunately, there were no data about the use of the Amsler chart for the follow-up of macular diseases in the mentioned studies. It is illogical to follow-up a patient suffering from a macular disease with FFA repeated three of four times per month, despite the presence of a harmless, noninvasive, and an accurate test such as the Amsler grid.

In this study, it was noticed that there was almost no apparent correlation between visual acuity and the presence of an Amsler grid abnormality. Whereas the Amsler grid has allowed some patients to recognize a central visual disturbance in the presence of excellent visual acuity, other patients with advanced macular lesions and reduced visual acuity failed to detect any Amsler grid abnormality. This is correlated with the observations of Fine et al. [13].

Abnormalities detected by the Amsler grid in patients with good visual acuity deepens the idea of qualitative vision. In a lecture by Marc Amsler titled 'quantitative and qualitative vision', he defined quantitative vision as 'what we measure everyday by means of our usual test types' [7]. Although quantitative vision is a quick and valuable measure of the minimal vision of the fovea, yet it is only a rough estimate. In the study by Nassar [2], Amsler grid testing predicted the lesion ahead by 2-6 months in 20 eyes compared with other diagnostic investigative instruments. This explains the idea of qualitative vision that is considered to be more sensitive than the quantitative one and the significant role of the Amsler grid to help the patient to find out, explain, and document these quantitative changes.

To conclude, the Amsler chart is a simple, straightforward, cheap, and safe technique that can be used in the detection and the follow-up of macular diseases with high sensitivity. These findings agree with that mentioned by Nassar [2], Klatt et al. [9], and Fine et al. [13] in their studies.


  Conclusion Top


The Amsler chart is a simple, inexpensive, noninvasive, harmless, portable, and suitable tool and of a mass screening ability that easily detects different macular lesions. The Amsler chart has the benefit of being a subjective test that helps patients to find out and analyze early symptoms of macular diseases and to follow-up the progress of their own disease, increasing their compliance for both treatment and follow-up. The Amsler chart should be used under the examiner's supervision with strict instructions given for its use.


  Acknowledgements Top


Conflicts of interest

None declared.

 
  References Top

1.
Nassar M. Threshold Amsler grid testing to detect reserving power of the macula and optic nerve. J Egypt Ophthalmol Soc 1996; 89 :1067-1071.  Back to cited text no. 1
    
2.
Nassar M. Resurrection of Amsler chart is it still valid. J Egypt Ophthalmol Soc 2003; 96 :445-451.  Back to cited text no. 2
    
3.
Marmor MF. A brief history of macular grids: from Thomas Reid to Edvard Munch and Marc Amsler. Surv Ophthalmol 2000; 44 :343-353.  Back to cited text no. 3
    
4.
Amsler M. Earliest symptoms of diseases of the macula. Br J Ophthalmol 1953; 37 :521-537.  Back to cited text no. 4
    
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Crossland M, Rubin G. The Amsler chart: absence of evidence is not evidence of absence. Br J Ophthalmol 2007; 112 :1579-1585.  Back to cited text no. 5
    
6.
Franklin A. Amsler assessment of visual fields. In: Doshi S, Harvey Weds. Investigative techniques and ocular examination. Elsevier; 2003. 135-138.  Back to cited text no. 6
    
7.
Amsler M. L′examen qualitative de la function maculaire. Ophthalmologica 1947; 114-261.  Back to cited text no. 7
    
8.
Walsh TJ. Visual fields: examination and interpretation. 3rd ed. Oxford University Press; 2011. 36.  Back to cited text no. 8
    
9.
Klatt C, Sendtner P, Ponomareva L, Hillenkamp J, Bunse A, Gabel VP, et al. Diagnostics of metamorphopsia in retinal diseases of different origins. Ophthalmologe 2006; 103 :945-952.  Back to cited text no. 9
    
10.
Schuchard RA. Validity and interpretation of Amsler grid reports. Arch Ophthalmol 1993; 111 :776-780.  Back to cited text no. 10
    
11.
Zaidi FH, Cheong-Leen R, Gair EJ, Weir R, Sharkawi E, Lee N, et al. The Amsler chart is of doubtful value in retinal screening for early laser therapy of subretinal membranes. The West London Survey. Eye (Lond) 2004; 18 :503-508.  Back to cited text no. 11
    
12.
Loewenstein A, Malach R, Goldstein M, Leibovitch I, Barak A, Baruk E, et al., Replacing the Amsler grid: a new method for monitoring patients with age-related macular degeneration. Ophthalmology 2003; 110 : 966-970.  Back to cited text no. 12
    
13.
Fine AM, Michael JE, Jane EE, Paula AP, JoAnn SS, Stuart LF. Earliest symptoms caused by neovascular membranes in the macula. Arch Ophthalmol 1986; 104 :513-514.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]


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