Reading performance in patients with glaucoma evaluated using the MNREAD charts

Background

Reading performance in glaucoma patients has yet to be studied. We hypothesized that glaucomatous visual field loss affects reading performance even in patients with good acuity and evaluated their reading performance quantitatively.

Methods

A cross-sectional, comparative, non-interventional study. Forty-nine patients with early-moderate glaucomatous visual field loss OU with visual acuity better than 1.0 in the better and 0.7 in the worse eye. Reading performance in glaucoma patients was examined by the Japanese version of the Minnesota Reading Acuity Chart (MNREAD) were compared to that of age-matched normal subjects (n = 30).

Results

The study subjects consisted of the 21 men and 28 women. The mean age was 53.3 ± 12.6 years. Diagnosis included primary open-angle glaucoma (n = 22), normal-tension glaucoma (n = 22), developmental glaucoma (n = 4) and exfoliation glaucoma (n = 1). Reading parameters of glaucoma patients examined by MNREAD were: maximum reading speed (MRS), 329.9 ± 55.4 characters per min.; critical print size (CPS), 0.24 ± 0.14 logMAR; reading acuity (RA), 0.02 ± 0.12 log MAR, significantly lower than those of normal subjects (MRS 363.0 ± 42.9, CPS 0.09 ± 0.13 logMAR, RA ?0.13 ± 0.10 logMAR, P < 0.01 for three parameters by unpaired t test). CPS in glaucoma subjects was negatively correlated with mean deviation of Humphrey Field Analyzer 10-2 and 30-2 programs in the better eye (r = ?0.402, P < 0.005; r = ?0.304, P < 0.05; respectively, by linear regression analysis).

Conclusions

The reading performance deteriorated even in glaucoma patients with good acuity.     

Reading acuity in children: evaluation and reliability using MNREAD charts

PURPOSE: To study reading acuity in children and assess the reliability of its measurement using the Italian version of the MNREAD reading chart. METHODS: One hundred sixteen children from grades 3 to 8 with normal near vision were tested at a pediatric eye care institution in northeastern Italy. Visual acuity was evaluated with Early Treatment Diabetic Retinopathy Study (ETDRS) charts and reading acuity with MNREAD charts. Examination with charts 1 and 2 by the same examiner in the same visit were used as test-retest measurements. RESULTS: Mean improvement of performance from grades 3 to 8 was approximately 1 line for ETDRS acuity and 1.5 sentences for reading acuity and critical print size. Mean maximum reading speed increased from 96 to 167 words/minute. Regression analysis showed that a stable reading speed was obtained throughout sentences of decreasing size up to the critical print size. Measurement error, expressed as 95% limits of agreement, was +/- 0.136 logarithm of the minimum angle of resolution (logMAR) and +/- 0.142 logMAR for ETDRS acuity and reading acuity, respectively. Critical print size had the lowest reliability (+/- 0.193 logMAR). Maximum reading speed limits of agreement were +/- 0.077 logarithm of words per minute (logWPM), or a 19% change in words per minute. There were no detectable effects of grade and refractive error on measurement errors. CONCLUSIONS: In children, MNREAD charts provide measurements of reading acuity as reliable as ETDRS chart measurements of distance acuity on a logMAR scale. They also provide highly reliable measurements of the maximum reading speed across all grades, independent of its noticeable increase.     

Mobility performance with retinitis pigmentosa

Purpose : Reduced mobility can have a serious impact on quality of life. Though previous studies have demonstrated that some vision measures relate to the mobility of subjects with simulated and true low vision, the relationship between residual vision and mobility is not clear. We investigated the relationship between clinical vision measures and mobility performance under different illumination levels for subjects with retinitis pigmentosa (RP). Methods : Binocular visual acuities, letter contrast sensitivities and static central threshold visual fields were measured on 10 subjects with RP and nine age-matched control subjects. Mobility performance was measured on an indoor mobility course at high and low illuminances and was assessed by percentage preferred walking speed (PPWS) and number of errors. Results : The RP group showed significantly reduced PPWS and greater numbers of errors than the control group. The reduction in illumination resulted in significantly worse error and PPWS scores. Unlike the control group, the presence of a glare source did not reduce the PPWS of the RP group under high illumination. Multiple regression analyses showed that the average visual field extent was the most significant predictor of mobility; letter contrast sensitivity and visual acuity added to the regression models for the low illumination measures to account for up to 75 per cent of the variation in mobility performance. Conclusions : People with RP have worse mobility than people with normal vision, more so under reduced illumination levels. Visual field extent was the strongest predictor of mobility performance. (Clin Exp Optom 1996; 80: 1: 1–12)     

Letter contrast sensitivity in retinitis pigmentosa patients assessed by Regan charts

Regan Contrast Sensitivity Letter Charts were used to assess the effects of reduced contrast and luminance on visual acuity in retinitis pigmentosa (RP) patients. Letter acuity was measured monocularly in 17 RP patients and in 14 age-similar normals using charts of three different contrast levels presented at each of four levels of illumination. Despite visual acuities of 20/40 or better under standard clinical test conditions, an appreciable number of RP patients were unable to identify any letters on the intermediate- and/or low-contrast Regan charts. For example, even at the recommended test luminance, 5 patients could not read any letters on the intermediate (11%) contrast chart, and 9 could not be scored on the low (4%) contrast chart. Consequently, the Regan charts were found to have limited usefulness in quantifying the exact extent of visual impairment in this group of RP patients. Nevertheless, our results document the degree of visual acuity loss that can be experienced by RP patients under conditions of low contrast and luminance.     

Reading speed of patients with advanced retinitis pigmentosa or choroideremia

PURPOSE: To quantify, account for, and enhance the reading speed of patients with generalized retinal degeneration and small central visual fields. METHODS: Thirty-three patients with retinitis pigmentosa or choroideremia and 12 normal controls participated in the study. The patients had visual acuities of 20/200 or better, central visual field diameters of < or =20 degrees, and log10 contrast sensitivities of < or =1.65. Reading speed was measured by having participants silently read timed sentences presented with differing font size, font type (Times vs. Courier), and text polarity (standard black text on a white background vs. reversed white text on a black background) and then recall that text aloud. RESULTS: The patients' mean reading speed for standard polarity text using the Times font and their optimal font size was 43% of normal (P < 0.001). Patient reading speed was significantly related to visual acuity (r = 0.44; P < 0.001) and to contrast sensitivity (r = 0.68; P < 0.001) but not to central visual field diameter. In a multiple regression model, only contrast sensitivity by itself was a strong independent predictor of patient reading speed, although visual acuity and visual field in combination did nearly as well. On average, the patients read significantly faster with the Times font than with the Courier font (P < 0.001). The percentage improvement in reading speed with reverse polarity text was most related to contrast sensitivity (r = 0.47; P < 0.001), and 83% of patients with log10 contrast sensitivity of <1.0 versus 36% with higher contrast sensitivity read faster with reverse polarity text (P = 0.02). CONCLUSION: Patients with retinitis pigmentosa or choroideremia and small central fields have, on average, impaired reading speed associated primarily with reduced contrast sensitivity, and those with very poor contrast sensitivity will most likely benefit from reversing text polarity.     

Visual performance using a retinal prosthesis in three subjects with retinitis pigmentosa

PURPOSE: To assess visual task performance in three blind subjects implanted with epiretinal prostheses. DESIGN: Prospective, investigational device exemption trial. METHODS: Three subjects with light perception or no light perception vision were enrolled at a single center. All subjects had retinitis pigmentosa (RP). Main inclusion criteria: light perception or worse vision in one eye and some visual experience as an adult before blindness. Main exclusion criteria included other ophthalmic problems. A prototype retinal prosthesis was implanted in the eye with worse light sensitivity. The prosthesis had 4 x 4 array of platinum electrodes tacked to the epiretinal surface. The prosthesis was wirelessly controlled by a computer or by a head-worn video camera. Visual function testing was performed in single masked or double masked fashion. Scores from the visual task were compared to chance to determine statistical significance. RESULTS: The subjects performed significantly better than chance in 83% of the tests. Using the video camera, subjects scored as follows on simple visual tasks: locate and count objects (77% to 100%), differentiate three objects (63% to 73%), determine the orientation of a capital L (50% to 77%), and differentiate four directions of a moving object (40% to 90%). A subset of tests compared camera settings using multipixels vs single pixels. Using multipixel settings, subjects performed better (17%) or equivalent (83%) in accuracy and better (25%) or equivalent (75%) in reaction time. CONCLUSIONS: Three RP implant subjects used epiretinal prostheses to perform simple visual tasks. Multipixel settings proved slightly more effective than single pixel settings.     

Driving performance of retinitis pigmentosa patients.

The driving performance of 42 patients with retinitis pigmentosa (RP) was compared with that of 87 control subjects. Although the patients with RP were involved in more isolated road accidents than the control group, 50% were not involved in any accident over the most recent 5-year driving period. When the associations between driving performance and case/control status were examined (the number of driving hours per week and driving years being taken into account), differences in the number of accidents between the 2 groups were significant because of a disproportionately high number of accidents caused by a subgroup of female RP patients. No significant correlations were apparent between central visual efficiency or peripheral field efficiency and number of road accidents.     

A field expander for patients with retinitis pigmentosa: a clinical study

An inexpensive, commercially available optical device was tested on 10 patients with retinitis pigmentosa to determine its value as a field expander for scanning and as an aid to mobility. Visual acuity and visual fields were measured with and without the expander, and the patients' subjective responses were monitored by a questionnaire that was administered at regular intervals during a 2- to 4-week period between test sessions. Six of the 10 subjects considered the device helpful in at least 1 important visual task and planned to continue using it.     

视网膜色素变性患者复明的希望

视网膜色素变性（RP）是一种遗传性视网膜疾病,其典型的临床表现为早期视杆细胞的退行性病变以及视锥细胞胞体相对长期的存活。目前实验研究证实,通过腺相关病毒载体和慢病毒载体将微生物型的光敏感通道蛋白channelrhodopsin-2或halorhodopsins导入RP模型鼠的视锥细胞胞体或其他细胞,可以使这些细胞获得光反应并激活视网膜传导通路,向视觉中枢传递视觉信息。因此,这为RP患者的复明带来了希望。     

Spatial judgments in patients with retinitis pigmentosa

Previous investigations into cortical plasticity in the presence of ocular disease have focused on central retinal damage. Perceptually, patients often report distortions of visual space which can be partially explained by perceptual filling-in. The mechanisms involved could also apply to peripheral field loss. Spatial interval discrimination was tested in 28 retinitis pigmentosa (RP) patients and a control group. When stimuli were presented to both hemispheres, bias did not differ whereas threshold was poorer in RP patients. When presenting the task to only one hemifield, bias was related to field asymmetry, but only in the left visual field, r² = .59. Brain laterality may be an important factor when examining changes in cortical function in response to peripheral system damage.     

Sector retinitis pigmentosa: a fluorescein angiographic study.

Flourescein angiography has been proved to be of value in the study of the chorioretinal abnormaliteis in sector retinitis pigmentosa. The findings from two patients, one being in an early and the other in a more advanced stage were analyzed. The pigment epithelium was found to be disturbed in a larger area than visible by ophthalmoscopy. In the impaired quadrant the retinal vessels were narrowed showing delayed and slow dye transit. Through the discolorated pigment epithelium leaky choriocapillaries were disclosed. Moreover, in the severly affected patient, areas missing choriocapillar perfusion and retinal circulation were also detected.     

Hemodynamic findings in patients with retinitis pigmentosa]

The hemodynamic status of 26 patients with retinitis pigmentosa was examined using video fluorescein angiography. The hemorheological parameters hematocrit, plasma viscosity, erythrocyte aggregation and erythrocyte rigidity were determined. The results were compared to a matched pairs-group. Video angiography showed for retinitis pigmentosa patients a normal arm-retina time and a significant increase of the arteriovenous passage time. The rheological parameters for both groups were within the reference range. Interestingly the hemodynamic disturbance of microcirculation could be demonstrated already in early stages with no ophthalmoscopic symptoms and no atrophy of retinal vessels detectable at the time. The results indicate that disturbance of the retinal hemodynamics in early stages of retinitis pigmentosa may play a role in the pathogenesis of the disease.     

Rhodopsin mutations in Chinese patients with retinitis pigmentosa

AIM: To determine the pattern of rhodopsin mutations in Chinese retinitis pigmentosa (RP) patients. METHODS: The rhodopsin gene was examined in 101 RP patients and 190 controls from Hong Kong. RESULTS: Three coding changes were identified: Pro347Leu, Ala299Ser, and 5211delC. Each protein sequence alteration was found in one patient. Ala299Ser also existed in two controls. CONCLUSION: The C-terminal nonsense mutation may cause mis-sorting of rhodopsin protein. The finding of controls with Ala299Ser suggests this is only the third missense alteration reported that does not cause RP. The expected frequency of rhodopsin mutations in RP is <7% (2/101=2.0%, 95% confidence interval: 0.2%-7.0%).     

Serum transferrin in patients with retinitis pigmentosa.

The CDG syndrome is a newly detected disorder with a carbohydrate defect in glycoproteins such as transferrin. As retinitis pigmentosa is a part of this syndrome, there could also be other subtypes of retinitis pigmentosa with a similar biochemical defect. Isoforms of serum transferrin were therefore analysed in 78 patients from different families with retinitis pigmentosa and showed slightly or moderately elevated values for less glycosylated isoforms in two families. The study suggests that abnormal glycoprotein metabolism manifested by elevated values of carbohydrate-deficient isotransferrins may be present in a small proportion of families with retinitis pigmentosa. The relationship between the glycoprotein defect and retinitis pigmentosa remains to be established.     

Visual field expansion in patients with retinitis pigmentosa

BACKGROUND: To determine the effectiveness of using spectacle-mounted prisms for field expansion in patients with retinitis pigmentosa (RP). METHODS: Vision-related activities of daily living (V-ADL) questionnaire scores and functional visual field score (FFS) measurements were conducted before and after a one-month trial of spectacle-mounted prisms in those patients with RP who had residual central visual fields of less than 10 degrees. RESULTS: 16 patients were recruited who met study inclusion criteria. Mean V-ADL and FFS at baseline were 67.6 (73%) and 22.9 (46%), respectively. After a 1-month trial using spectacle-mounted prisms, V-ADL and FFS demonstrated significant improvement to 73.4 (80%, p < 0.05) and 27.0 (54%, p < 0.001), respectively. INTERPRETATION: Spectacle-mounted prisms effectively create visual field expansion and noticeable spatial orientation benefits in patients with RP. This may provide an adjunctive tool in low vision rehabilitation and should be considered in all cases with RP with less than 10 degrees of visual field.