Quantification of Metamorphopsia in Patients with Epiretinal Membranes Chota Matsumoto, Eiko Arimura, Sachiko Okuyama, Sonoko Takada, Shigeki Hashimoto, and Yoshikazu Shimomura PURPOSE. To quantify the degree of metamorphopsia in patients In 1999, we developed a new metamorphopsia chart (M- with idiopathic epiretinal membranes (ERMs), by use of a new CHARTS; Inami) for evaluating the degree of metamorphop- metamorphopsia chart (M-CHARTS) developed by the authors. sia.9 In this study, we tried to quantify the degree of metamor- METHODS. These M-CHARTS had 19 dotted lines with dot inter- phopsia in patients with idiopathic epiretinal membrane (ERM) vals of between 0.2° (fine) and 2.0° (coarse) visual angles. As using this new metamorphopsia chart. the dot intervals were changed from fine to coarse, a decrease in the severity of metamorphopsia was noted. In this study, the minimum visual angle of the dotted lines needed to cause the METHODS metamorphopsia to disappear was measured in 51 eyes of 51 patients with ERM. The metamorphopsia scores were com- Subjects pared with the stages of ERM classified by scanning laser Forty-seven eyes of 47 normal subjects (29 women, mean age, 56.4 ophthalmoscope (SLO) images. years; range, 23–78) and 51 eyes of 51 patients with ERM (31 women, RESULTS. In patients with ERM, the metamorphopsia score mean age, 64.3 years; range, 44–80) were studied. Each subject un- increased depending on the severity of membrane proliferation derwent a complete ophthalmic examination, which included best classified by SLO images. The scores obtained from the hori- corrected visual acuity, slit lamp biomicroscopy, applanation tonome- zontal dotted lines were larger than those of the vertical lines try, dilated funduscopy, fundus photography and scanning laser oph- in advanced stages of ERM. thalmoscopy (SLO, Rodenstock). The inclusion criteria for normal CONCLUSIONS. M-CHARTS provide a very simple and useful subjects were as follows: corrected visual acuity of more than 1.0, method for evaluating the severity of metamorphopsia in pa- pupil diameter of more than 3.0 mm, intraocular pressure of less than tients with ERM. (Invest Ophthalmol Vis Sci. 2003;44: 21 mm Hg, no ocular and systemic diseases that were likely to affect 4012–4016) DOI:10.1167/iovs.03-0117 their visual functions. One randomly selected eye was examined. The inclusion criteria for ERM patients were as follows: corrected visual n cases of macula disease, metamorphopsia is one of the acuity of more than 0.1, pupil diameter of more than 3.0 mm, intraoc- Imost important symptoms for evaluating visual functions. ular pressure of less than 21 mm Hg, and no systemic diseases that Amsler charts are widely used for detecting metamorphop- were likely to affect their visual functions. If ERMs were observed in sia.1,2 However it is difficult to evaluate the degree of meta- both eyes, one randomly selected eye was examined. Informed con- morphopsia quantitatively using Amsler charts. Previous inves- sent was obtained from all normal subjects and ERM patients. All tigators have tried to evaluate the quantification of experiments were performed in accordance with the Declaration of metamorphopsia, micropsia, and macropsia.3–7 However, Helsinki for research involving human subjects. these methods used complicated procedures and could not be applied for clinical use. In 1989, we reported a method for Fundus Examination quantification of metamorphopsia using a computer display Dilated funduscopy, fundus photography and SLO images with an and our own program.8 In this method, two circles were argon blue laser beam were used for detection of ERMs. We classified shown on the fixation point and in the central 10° visual field, the severities of the membrane proliferation by SLO images and fundus respectively. The size of these circles was made to match using photographs according to the Nakajima’s classification: stage 1: water the computer mouse buttons to quantify the metamorphopsia. silk reflex and transparent membrane; stage 2, vascular tortuosity of Using this method, it was possible to quantify the metamor- mascular vessesl and transparent membrane; stage 3, opaque or dense phopsia in the cases of serious metamorphopsia. However, fine membranes.10 metamorphopsia near the fixation point was undetectable with this method. Quantification of Metamorphopsia In patients with metamorphopsia, a straight line projected onto the From the Department of Ophthalmology, Kinki University School retina is recognized as an irregular or curved line. When a dotted line of Medicine, Osaka, Japan. is used and the dot interval changes from fine to coarse, metamorphop- Supported by Grant 12671731 from the Ministry of Education of sia decreases and finally disappears. Figure 1 showed the simulation of the Japanese Government and the Osaka Medical Research Foundation the metamorphopsia on a straight line and two different kinds of for Incurable Diseases. dotted lines. Originally, these three lines were completely straight. The Submitted for publication February 4, 2003; revised March 16, same degrees of computer generated random distortion to the hori- 2003; accepted April 3, 2003. zontal direction were added to all three lines. In this simulation, it is Disclosure: C. Matsumoto (P); E. Arimura, None; S. Okuyama, clear that the dot interval changes from fine to coarse, the distortion of None; S. Takada, None; S. Hashimoto, None; Y. Shimomura, None lines decreases and finally disappears. Based on this phenomenon, we The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked “advertise- developed a new chart with 19 kinds of dotted lines with dot intervals ment” in accordance with 18 U.S.C. §1734 solely to indicate this fact. of between 0.2° to 2.0° visual angles (Fig. 2). The type (II) dotted line Corresponding author: Chota Matsumoto, Department of Ophthal- was designed for patients with central scotoma such as a macular hole. mology, Kinki University School of Medicine, Ohno-Higashi, Osaka- The minimum visual angle of the dotted line needed to cause the Sayama City, Osaka 589-8511, Japan; [email protected]. metamorphopsia to disappear was measured. At first, a vertical straight Investigative Ophthalmology & Visual Science, September 2003, Vol. 44, No. 9 4012 Copyright © Association for Research in Vision and Ophthalmology Downloaded from iovs.arvojournals.org on 09/27/2021 IOVS, September 2003, Vol. 44, No. 9 Quantification of Metamorphopsia 4013 FIGURE 3. Method of detecting metamorphopsia using M-CHARTS. The minimum visual angle of the dotted lines needed to cause the metamorphopsia to disappear was measured. RESULTS FIGURE 1. Simulation of metamorphopsia. Computer generated ran- The case was a 64-year-old woman with ERM in her right dom distortion to the horizontal direction were added to all three lines. As the dot interval was changed from fine to coarse, there was noted eye. Her right corrected vision was 0.4. Figure 4 shows an a decrease in the severity of metamorphopsia. SLO image of his right eye. The fine metamorphopsia was detected by Amsler charts of her right eye (Fig. 5). The metamorphopsia was also detected by the horizontal line on line (0°)onthefirst page of M-CHARTS is shown to patients, and the the M-CHARTS. However, the dot interval changed from patients fixated on a fixation point on the center of the line. If the “fine” to “coarse,” and there was a noted decrease in the patients recognized the straight line as straight, the metamorphopsia severity of metamorphopsia. When a dotted line of which score is 0. If the patients recognize the straight line as an irregular or the dot interval was a 0.6° visual angle was used, her meta- curved line, then the following pages of M-CHARTS that have the morphopsia completely disappeared (Fig. 6). Therefore, her metamorphopsia score with the horizontal line was deter- dotted lines where interval changes from fine to coarse are shown to mined to be 0.6. The vertical lines of the M-CHARTS was also the patients one after another (Fig. 3). When the patients recognized a tested in a similar way. The metamorphopsia score with the dot line as straight, its visual angle is considered as their metamorphop- vertical line was 0.4. sia score. Also, the M-CHARTS are rotated 90° and the same test is The intraindividual variation of the metamorphopsia score performed using horizontal lines. In this study, the examinations were was within one line (Ϯ0.1 score) in all subjects with ERM. The repeated three times for each subject to evaluate the reproducibility of metamorphopsia scores were 0 in all normal subjects. The the test. The patient’s fundus information was completely masked from sensitivity of this method for detecting metamorphopsia was the examiner during the examination. 97.3% and specificity was 100% using the result of the Amslar charts as a standard. The stages of the ERM patients were as follow; 12 eyes with stage 1 (mean age, 68.08 Ϯ 9.0 years), 13 eyes of stage 2 (mean age, 67.5 Ϯ 6.2 years) and 26 eyes of stage 3 (mean age, 61.0 Ϯ 7.5 years). Figure 7 shows the relationship FIGURE 2. Design and examination conditions of M-CHARTS. The dot interval of the example dotted lines is 0.4. FIGURE 4. SLO image of ERM using argon blue laser beam. Downloaded from iovs.arvojournals.org on 09/27/2021 4014 Matsumoto et al. IOVS, September 2003, Vol. 44, No. 9 usually observed in early stages of ERM is detected by fine dotted lines; however, it is not detected by coarse dotted lines. In advance stages of ERM, the large amplitude and low frequency components of metamorphopsia in- crease, so it is easy to detect by all kinds of lines, including coarse dotted lines.