Koichi Oda

Patients with central serous chorioretinopathy (CSC) often complain of visual difficulties under low luminance conditions. In this study, we evaluated low luminance visual acuity (LLVA) after half-dose verteporfin photodynamic therapy (hdPDT) in eyes with CSC. The study included eight eyes of eight patients with chronic CSC that underwent hdPDT. The best-corrected visual acuity, LLVA and optical coherence tomography (OCT) findings were evaluated at baseline, and at 1, 3, 6, 9, and 12 months after hdPDT. LLVA was measured at six levels of background luminance. Serous retinal detachment was completely resolved in all eyes. Although the mean LLVA at 1 month did not improve significantly compared to baseline at all luminance levels, significant improvements were observed at 3, 6, 9, and 12 months (p < 0.05). In OCT images, although the ellipsoid zone was not detectable in all eyes before hdPDT, it was observed in 2 eyes at 1 month, in 7 eyes at 3 months, and in all eyes from 6 months. The LLVA and the ellipsoid zone improved similarly with postoperative time courses. In conclusion, hdPDT improves LLVA in eyes with chronic CSC. The recovery of the ellipsoid zone may play a part in improving LLVA after hdPDT.

This study examined the effect of character sample density on legibility. As the spatial frequency component important for character recognition is said to be 1 to 3 cycles/letter (cpl), six dots in each direction should be sufficient to represent a character; however, some studies have reported that high-density characters are more legible. Considering that these seemingly contradictory findings could be compatible, we analyzed the frequency component of the character stimulus with adjusted sample density and found that the component content of 1 to 3 cpl increased in the high-density character. In the following three psychophysical experiments, high sample density characters tended to have lower contrast thresholds, both for normal and low vision. Furthermore, the contrast threshold with characters of each sample density was predicted from the amplitude of the 1 to 3 cpl component. Thus, while increasing the sample density improves legibility, adding a high frequency is not important in itself. The findings suggest that enhancing the frequency components important for recognizing characters by adding the high-frequency component contributes to making characters more legible.

<p>This study aims to explain as quantitatively as possible the readability of Japanese characters in terms of certain elements in the multi-dimensional, and rather qualitative, space of font design. Based on a review of previous studies, two main dimensions have been selected as the most influential on readability ; the relative character size in the bounding box, which we call style, and the stroke width, which we call weight (when discussed in a categorical way). The Gothic fonts were chosen as the target because they are well known to be the most legible. Behavioral evaluations of readability were conducted instead of subjective judgments. In accordance with the reading acuity measurement MNREAD-J, short and easy-to-read sentences were presented to participants, and the time required to read them aloud was recorded along with any reading errors ; this provided three readability indices. Sentences were rendered in one of 12 different fonts consisting of four kinds of style-Old, Standard, Modern, and UD-times three weight levels-Light, Regular, and Bold. Findings for the style suggest that the enlargement of relative size represents a tradeoff with narrowed inter-letter spacing. This means that good legibility of single letter design may not result in good readability of letters in sentences. However, the weight had a notable effect especially in small sizes. Two readability indices were predicted relatively well by participants' acuity and stroke width. The effect of stroke width had a ceiling between 10 and 15 ％ of the letter size.</p>

Background: The aim was to determine the low luminance visual acuity in eyes with central serous chorioretinopathy. Methods: Seven eyes of seven patients with central serous chorioretinopathy and six eyes of six age-matched normal volunteers were examined. Low luminance visual acuity charts were created by an Apple Power Mac G5 computer and displayed on a cathode ray tube monitor (SONY GDM-F500). The background luminance was set at six different levels from 78.20cd/m2 to 0.37cd/m2. The visual acuities of the eyes with central serous chorioretinopathy at each of the six luminance levels were compared to those from their fellow eyes and to normal eyes. Results: The mean visual acuities varied from 0.13, 0.23, 0.29, 0.42, 0.62 to 0.70 logMAR units as luminance varied from high to low. At the lowest luminance (0.37cd/m2), five of the seven eyes could not read any character. The mean visual acuities of the fellow eyes at the same luminance levels were 0.03, 0.06, 0.11, 0.20, 0.27 and 0.45 logMAR units and those of the normal volunteers were 0, 0.03, 0.08, 0.14, 0.23 and 0.38 logMAR units, respectively. The visual acuities of the eyes with central serous chorioretinopathy were significantly poorer than those of the normal eyes at all luminance levels except 0.37cd/m2 (p&lt 0.05 for all). Conclusions: Although the eyes from all three groups had 0 logMAR units visual acuity under standard testing condition, the visual acuity of the eyes with central serous chorioretinopathy were significantly worse at low luminance levels. The low luminance visual acuity may provide information on the visual disturbances reported by central serous chorioretinopathy patients with 0 logMAR units visual acuity. © 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

フリークライミングは視覚障害者にも適したスポーツであり，教育的利用価値があるスポーツと言える。著者らは2008年より筑波技術大学の視覚障害学生を対象とした体育集中授業として導入された「フリークライミング」の授業指導を行ってきた。ここでは視覚障害に配慮した上で，登るという身体的な技術指導のみならずパートナーシップや自己責任などに着目した心理的効果を引き出す独自のプログラムを実施した。本研究の目的はこのプログラムの有用性を検証することである。2010年度の受講生9名（男性5名，女性4名，弱視9名）を対象に，フリークライミング（以下，クライミングと略す）の体験過程と前後での変化を調べるため自己効力感尺度，自由記述式質問紙，インタビュー，ビデオ分析を行い，総合的に考察を試みた。その結果，クライミングを活用した体育カリキュラムの有用性が示された。

The estimation of optimal print size for reading is often essential in clinical treatment and/or universal design however, it is not known how to calculate the proper letter size for reading with maximum efficiency. Psychophysics studies have revealed psychometric functions of reading that exhibit a hill-like shape with a plateau of maximum speed and a downfall beyond Critical Print Size (CPS). To control the magnification rate of visual aids for patients with visual impairments, CPS that can indicate the boundary of maximum efficiency is now becoming a noteworthy index to determine optimal letter size. In addition to reading, word searching is also an important task for our living. However, the CPS of word search tasks has not been examined yet. We estimated the CPS of word search from the results of two experiments focused on searching for words in Chinese characters and Japanese alphabet (Katakana: square forms) in Japanese. The functions of the searching tasks showed a hill-like shape almost identical to the reading tasks but with elevated speed, and the CPS were stable around 0 log MAR in both the reading and the searching tasks. Hence, CPS is unsusceptible to tasks and can function as a robust marker for the smallest print size with maximum speed. This finding indicates that CPS is the threshold of proficiency (maximum/reduced) beyond the threshold of vision (visible/invisible). CPS can be a meaningful index to achieve the appropriate control of print size and subsequently help people with visual problems.

The purpose of the present research was to determine the usability of the critical size of characters in presentations projected at a distance for people with low vision. In Experiment 1, which simulated low vision in people with normal vision, 2 variables were evaluated: character size (3 sizes) and reading style (2 styles). The results showed that reading speed was significantly faster when print size was at least a critical size than it was when print size was smaller than the critical size, and that there was an interrelation to the results of the reading evaluation tests. This suggested that critical print size may be used as a standard in determining character size for large-scale projected presentation. Some of the results from the participants in Experiment 2, who were people with low vision, were greatly similar to those from Experiment 1; however, in some cases, the results did not exactly match those from Experiment 1. The results of these experiments suggest that although critical print size may indeed serve as a good standard for determining character size for use with people with low vision, it is also important to make adjustments on the basis of the opinions of readers with low vision.

An interesting field of basic research in psychology of sensation and perception named "psychophysics of reading" developed in the process of solving problems practitioners have been facing in the fields of special education and rehabilitation for persons with visual impairments. Psychophysical study of relationship between stimulus dimensions, such as spatial resolution, contrast, and visual field size and reading speed gave us basic understanding about our reading behavior as well as a good tool to help persons with visual impairments find suitable aids and environmental modification in order to ease their reading difficulty. Especially the reading speed function of print size for each patient gives us a very sensitive measure about patient's quality of vision. As an example, one of our recent findings showed that the reading function explained the claim of degraded vision from a patient with ring scotoma better than usual visual acuity measure.

This study compared two methods and evaluated their effectiveness when prescribing reading aids to low vision patients with age-related macular degeneration (AMD). One method was rather traditional and based on patients' near acuity. The other was based on patients' reading performances measured with the MNREAD-J reading charts.<br>Subjects were nineteen low vision patients with scar-stage AMD in their both eyes and prescribed reading aids for newspaper at the Surugadai-Hospital, Nihon University. In the initial evaluation, patients were measured their near acuity and reading performances. Magnification power of the aids were then determined according to the two different methods: in the traditional method, the power was 0.4 divided by individual patient's near acuity in decimal unit, while it was calculated as M value of critical print size measured with MNREAD-J in the new method. A certain number of reading aids of the determined power were then presented to the patient and she/he tried to read newspaper with the aids. Her/his reading performance was measured and comparison was made among aids. Finally, one or two suitable aids were selected and lent. After one-week through one-month trial period, the aid was prescribed if appropriate.<br>For all patients, the magnification power predicted by near acuity was always lower than the power actually prescribed. Regression analysis showed that the difference was about factor of four. The power of prescribed aids were very close to what predicted with M value measured with the MNREAD-J. The MNREAD-J also gave us the method of statistical and objective evaluation of validity in selection of aids.<br>Our findings showed that the method based on reading measurements with MNREAD-J was more time-saving and appropriate than the traditional method based on the near acuity when prescribing reading aids to low vision patients with AMD.