Thesis (MPH.) -- University of Limpopo, 2015 / Purpose: The purpose of this study was to determine the prevalence and causes of visual impairment (low vision and blindness) among eye clinic patients at Nkhensani hospital in Limpopo province, South Africa. Methods: This was a cross sectional design in which 400 stratified participants aged ≥ 6 years were selected {100 participants in each stratum (6 – 18; 19 – 35; 36 – 59 and ≥ 60 years)}. Presenting, pinhole and best corrected visual acuities were measured using a logMAR E chart. Where reduced visual acuity (VA) was due to uncorrected refractive errors (UREs), ophthalmic lenses were used to compensate for the refractive errors using subjective refraction method and best corrected VA was measured. All participants underwent external and internal ocular examinations using ophthalmoscope to detect eye diseases. Participants with ocular pathology were referred to the ophthalmic nurse and/or ophthalmologist for further management. Refractive error findings were elaborated on in this study in order to highlight the importance and impact of this eye condition. Results: The ages of participants ranged from 6 to 92 years with mean of 39.5 ± 23.5 years. They included 161 (40.3%) males and 239 (59.8%) females. The prevalence of significant visual impairment (SVI) (VA < 6/18 to no light perception, i.e. low vision and blindness), low vision and blindness based on presenting visual acuity (PVA) in the right eye were 34.8%, 16.3% and 18.5% respectively while the prevalence based on the best corrected VA were 24.0%, 7.5% and 16.5% respectively. Based on the PVA, there was a significant association between age (Chi = 71.6; df =3; p = 0.00) and gender (Chi = 8.9; df =1; p = 0.003) with visual impairment (VI) of the right eye. In the left eye, the prevalence of SVI, low vision and blindness based on PVA were 35.8%, 17.5% and 18.3% respectively, while the prevalence based on best corrected VA were 24.8%, 8.5% and 16.3% respectively. Based on PVA, there was a significant association between age and visual impairment in the left eye (Chi = 52.9; df =3; p = 0.00) but there was no association between gender and VI (Chi = 1.9; df =1; p = 0.163). In both eyes, the prevalence of SVI, low vision and blindness based on PVA were 27.0%, 17.5% and 10.3% respectively, while the prevalence based on best corrected VA were 16.8%, 3.8% and 9.5% respectively. Based on the PVA, there was a significant association between age and VI (Chi = 54.1; df =3; p = 0.00) and gender and VI (Chi = 4.7; df =1; p = 0.03) in both eyes. iv The causes of significant visual impairment were uncorrected refractive errors (38.0%), cataract (25.9%) and glaucoma (17.6%) in both eyes. Among all participants, the leading causes of low vision based on presenting VA were uncorrected refractive errors (56.7%), cataract (20.9%) and glaucoma (9.0%). The main causes of blindness in both eyes were cataract (34.1%), glaucoma (31.7%) and corneal anomalies (17.1%) based on presenting visual acuity. After optical corrections, the main causes of VI were cataract (39.4%), glaucoma (28.8%) and corneal anomalies (18.2%). The main causes of low vision were cataract (42.9%), glaucoma (21.4%) and corneal anomalies (17.9%), while the main causes of blindness were cataract (39.5%), glaucoma (34.2%) and corneal anomalies (15.8%). Conclusion: The findings in this study indicate that the overall prevalence of visual impairment, low vision and blindness among patients attending the Nkhensani hospital eye clinic were 27.0%, 16.8% and 10.3% respectively. The main causes of visual impairment, low vision and blindness were uncorrected refractive errors, cataract and glaucoma. A focus on the optical correction of refractive errors and surgical intervention in the case of cataract would lead to a significant reduction in the burden of visual impairment among patients who utilise Nkhensani hospital for eye care services. Also, early detection and appropriate management of glaucoma will reduce the burden of this ocular morbidity. A significant proportion of these prevailing ocular morbidities are avoidable and with appropriate management, visual impairment is preventable.

Many individuals with impaired vision experience a decreased quality of life. Quality of life is defined as "the degree to which an individual enjoys the important possibilities of their life. " Vision rehabilitation outcomes primarily focus on the functional impacts of interventions, with less attention being paid to any associated psychosocial impacts. This study examines the relationship between measures of visual function status and psychosocial status in individuals acquiring low vision assistive devices for the first time. One hundred and twenty subjects were evaluated after purchasing their first low vision device from a University-based low vision clinic. The measures used were the National Eye Institute Visual Function Questionnaire (NEI-VFQ 25) and the Psychosocial Impact of Assistive Devices Scales (PIADS). The NEI-VFQ 25 measures the status of visual function, while PIADS is a device impact measure, which explores the psychosocial impact of devices on three domains: competence, adaptability, and self-esteem. This study determines the strength of association between these two measures at initial and follow-up administrations, and between each subsequent measure as a result of the time interval between administrations, in addition to assessing whether or not a change in stability for the measures occurred over time. Modest strengths of associations were anticipated and the short time interval was not expected to be a factor in change in stability of the measures. The expectation was that subjective reports of functional changes should have a moderate correlation with psychosocial impact.

Syfte: Syftet med denna studie var att jämföra Multilens Bilux Iris-glas mot deras vanliga polariserade filterglas på syncentralspatienter med uttalade bländningsbesvär. Metod: I studien undersöktes 15 personer mellan 42-89 år. Försökspersonerna som hade bokad tid hos Syncentralen i Kalmar fick valet att ställa upp på en studie där de skulle få testa ytterligare ett filterglas. Patienterna återkallades efter ett par veckor då synskärpetester gjordes i hög och lågkontrast med och utan bländningsbelysning. Undersökningen innefattade även en intervju under vilken patienten fick berätta vad han/hon tyckte om respektive glas. Resultat: Kontrast påverkade visus. Högkontrast visus påverkades inte nämnvärt med olika filterglasen eller bländning. För lågkontrast visus fanns heller ingen signifikant skillnad mellan filterglasen med eller utan bländning. En del patienter upplevde bättre synförhållanden med Bilux i vissa situationer. Slutsats: Högkontrast samt lågkontrast visus påverkades inte nämnvärt med de olika filterglasen eller med bländning. Subjektivt upplevdes förbättrade synförhållanden i vissa situationer med Bilux och vanliga filterglas. / The aim of this study was to compare Multilens Bilux Iris against their regular polarized filter-glasses on low vision subjects with pronounced light sensitivity. A total of 15 people aged 42-89 years participated in the study. All were patients at the low-vision clinic at the hospital in Kalmar, Sweden. Patients were recruited during a prior routine examination whereby they were asked if they would be willing to participate in a study in which they would have the chance to try an extra pair of filter-glasses. The patients were recalled after a few weeks for the examination. Patients’ high- and low contrast visual acuity was measured both with and without glare. An interview with all of the patients was also conducted regarding the different filter lenses. This study showed no significant difference in high contrast or low contrast visual acuity, with or without the different filters examined during this study. A subjective difference was however detected between filters under certain situations.

Many individuals with impaired vision experience a decreased quality of life. Quality of life is defined as "the degree to which an individual enjoys the important possibilities of their life. " Vision rehabilitation outcomes primarily focus on the functional impacts of interventions, with less attention being paid to any associated psychosocial impacts. This study examines the relationship between measures of visual function status and psychosocial status in individuals acquiring low vision assistive devices for the first time. One hundred and twenty subjects were evaluated after purchasing their first low vision device from a University-based low vision clinic. The measures used were the National Eye Institute Visual Function Questionnaire (NEI-VFQ 25) and the Psychosocial Impact of Assistive Devices Scales (PIADS). The NEI-VFQ 25 measures the status of visual function, while PIADS is a device impact measure, which explores the psychosocial impact of devices on three domains: competence, adaptability, and self-esteem. This study determines the strength of association between these two measures at initial and follow-up administrations, and between each subsequent measure as a result of the time interval between administrations, in addition to assessing whether or not a change in stability for the measures occurred over time. Modest strengths of associations were anticipated and the short time interval was not expected to be a factor in change in stability of the measures. The expectation was that subjective reports of functional changes should have a moderate correlation with psychosocial impact.

Reading is one of the most important activities in most people’s life. For children, reading is a window to knowledge, good educational achievement and better job opportunities in the future. Thus reading fluency is a very important factor in the child’s education. Children and young adults with low vision usually use a close working distance to gain relative distance magnification. Unlike adults, they have active accommodation. Many studies, however, have shown that children and young adults with low vision have reduced accommodation response compared to the norms of their age. Reading additions (high plus lenses) can correct for this reduction in accommodation and may be an optimum method of prescribing magnification in younger adults with low vision. There have been no studies to verify the best method of prescribing reading additions in young adults with low vision and few studies of their effect on reading performance. This is the first study to compare different methods to determine reading additions and their effect on reading performance in young adults with low vision. The aims of the present study are 1) to investigate if three different methods to determine reading additions would lead to significantly different dioptric powers 2) to determine which method (if any) would lead to better reading performance. Reading performance was assessed by measuring the maximum reading speed, critical print size (CPS), print size threshold and the area under the reading speed curve. This was an experimental study involving thirty participants with low vision aged between 8 to 35 years. Participants were recruited from the Low Vision Clinic at the School of Optometry, University of Waterloo, Canadian National Institute for the Blind (CNIB) and the Vision Institute of Canada. All participants underwent a routine clinical examination including distance visual acuity, near visual acuity, Pelli-Robson contrast sensitivity, unilateral cover test, static retinoscopy, subjective refraction and measurement of the habitual reading distance. A questionnaire was used to determine their usage of any low vision aids, their perceived difficulty with reading and time spent reading. Reading additions were determined by 1) an objective method using Nott dynamic retinoscopy 2) an age-based formula 3) a subjective method based on the participant’s response to lenses. Reading tasks and dynamic retinoscopy were conducted at a fixed working distance of 12.5cm. Reading performance was assessed using MNREAD-style reading charts with each of the reading additions and without a reading addition, in a random order. Sentences were arranged in way that no sentence was repeated by the same participant. Participants were timed with a stop watch in order to calculate the reading speed in correct words per minute (CWPM). Reading speeds were plotted against print size to calculate the maximum reading speed, the critical print size, MNREAD threshold and the area under the reading speed curve. The participant’s mean age was 16 (± 6) years. There were equal number of males and females. The mean distance visual acuity of the tested eye ranged from 0.357 to 1.184 logMAR with a mean of 0.797 ± 0.220 logMAR. The near visual acuity ranged between 0.301 to 1.301 logMAR with a mean of 0.80 ± 0.26 logMAR. There were six participants who already had a reading addition. Maximum reading speed ranged between 52 to 257 wpm (165 ± 61 wpm). Critical print size ranged between 0.325 to 1.403 logMAR (0.965 ± 0.279 logMAR). Repeated measures ANOVA on the whole group showed that there was a significant difference between the reading additions (p=0.001). The retinoscopy reading addition power was significantly lower than the age add (p=0.002) and the subjective add (p=0.038). Repeated measures ANOVA did not show any improvement of any of the reading measures with the reading additions compared to without the reading addition. A re-analysis was undertaken excluding participants who had normal accommodation at 12.5cm. The results of repeated measures ANOVA showed that there was no significant difference in the dioptric powers obtained by the three methods, although, all reading addition power were significantly greater than zero (t-test <0.0005). There was a significant difference in the area under the reading speed curve (p=0.035), which was greater with the subjective addition than with no reading addition (p=0.048). The MNREAD threshold significantly improved with the age addition compared to no addition (p=0.012). There was a large variability between the participants in their response to a reading addition. Analysis of individual data showed that some participants showed a clear improvement in reading performance with a reading addition. Other participants did not demonstrate any obvious improvement in reading performance with reading additions. Of those participants who showed an improvement, all but one participant had abnormal accommodation. However, not all participants who did not show an improvement had normal accommodation. Univariate analysis and forward step-wise linear regression analysis were used to investigate if any improvement in reading performance and the habitual reading performance without a reading addition could be predicted by factors that were measured in the study. These factors included distance visual acuity, near visual acuity, contrast sensitivity, lag of accommodation, age, time spent on reading each day, perceived difficulty of reading regular print and whether or not the participant received training for the usage of his/her low vision aids. Improvement in reading performance could not be predicted by any of these factors. Habitual reading performance without a reading addition was correlated with some factors. Univariate analysis showed that critical print size was associated with MNREAD threshold (r=0.904. p<0.0005), distance visual acuity (r=0.681, p<0.0005) and contrast sensitivity (r=-0.428, p=0.018) and MNREAD threshold without an addition was associated with the contrast sensitivity (r=-0.431, p=0.017,) and distance visual acuity (r=0.728, p<0.0005). Difficulty of reading correlated with near visual acuity (Spearman correlation coefficient=0.620, p=0.0009), MNREAD threshold (Spearman correlation coefficient=0.450, p=0.02) and maximum reading speed (Spearman correlation coefficient=-0.472, p=0.014). Time spent on reading each day correlated with the area under the reading speed curve (Spearman correlation coefficient=0.659, p=0.0024). The multiple regression analysis showed that MNREAD threshold was best predicted by distance visual acuity (R=0.728, p <0.0005), critical print size could be predicted by distance visual acuity (R=0.681, p <0.0005) and age (R=0.748, p=0.022) and the power of the subjective addition could be predicted by age (R=0.583, p=0.001) and near visual acuity (R=0.680, p=0.028). There was evidence that a reading addition improved reading performance as measured by the area under the curve and MNREAD (reading acuity) thresholds, but this was not predicted by any visual factor, except that all those who gained improvement had poor accommodation. Therefore, it is recommended that an eye care practitioner should demonstrate a reading addition in a low vision assessment of children and young adults, particularly with patients who have reduced accommodation.

In the context of a society were the Web is present in many aspects, there is asignificant amount of visually impaired users whose experience is far from beingsatisfactory. There are technologies aiming this problem but still with no full suc-cess. The problem addressed in this project is the existing gap between the visuallyimpaired users and the solutions being offered to them. As a solution to this problem,a middleware prototype is developed. It acts as a web application so the user doesnot need to install anything. The middleware also offers different adaptations to theuser such as amplifying lens, text narrator, and others. The solution was tested byvisually impaired users and it received an overall positive result. Some features likethe amplifying lens received a good value and some of them need further improve-ment.

Reading is one of the most important activities in most people’s life. For children, reading is a window to knowledge, good educational achievement and better job opportunities in the future. Thus reading fluency is a very important factor in the child’s education. Children and young adults with low vision usually use a close working distance to gain relative distance magnification. Unlike adults, they have active accommodation. Many studies, however, have shown that children and young adults with low vision have reduced accommodation response compared to the norms of their age. Reading additions (high plus lenses) can correct for this reduction in accommodation and may be an optimum method of prescribing magnification in younger adults with low vision. There have been no studies to verify the best method of prescribing reading additions in young adults with low vision and few studies of their effect on reading performance. This is the first study to compare different methods to determine reading additions and their effect on reading performance in young adults with low vision. The aims of the present study are 1) to investigate if three different methods to determine reading additions would lead to significantly different dioptric powers 2) to determine which method (if any) would lead to better reading performance. Reading performance was assessed by measuring the maximum reading speed, critical print size (CPS), print size threshold and the area under the reading speed curve. This was an experimental study involving thirty participants with low vision aged between 8 to 35 years. Participants were recruited from the Low Vision Clinic at the School of Optometry, University of Waterloo, Canadian National Institute for the Blind (CNIB) and the Vision Institute of Canada. All participants underwent a routine clinical examination including distance visual acuity, near visual acuity, Pelli-Robson contrast sensitivity, unilateral cover test, static retinoscopy, subjective refraction and measurement of the habitual reading distance. A questionnaire was used to determine their usage of any low vision aids, their perceived difficulty with reading and time spent reading. Reading additions were determined by 1) an objective method using Nott dynamic retinoscopy 2) an age-based formula 3) a subjective method based on the participant’s response to lenses. Reading tasks and dynamic retinoscopy were conducted at a fixed working distance of 12.5cm. Reading performance was assessed using MNREAD-style reading charts with each of the reading additions and without a reading addition, in a random order. Sentences were arranged in way that no sentence was repeated by the same participant. Participants were timed with a stop watch in order to calculate the reading speed in correct words per minute (CWPM). Reading speeds were plotted against print size to calculate the maximum reading speed, the critical print size, MNREAD threshold and the area under the reading speed curve. The participant’s mean age was 16 (± 6) years. There were equal number of males and females. The mean distance visual acuity of the tested eye ranged from 0.357 to 1.184 logMAR with a mean of 0.797 ± 0.220 logMAR. The near visual acuity ranged between 0.301 to 1.301 logMAR with a mean of 0.80 ± 0.26 logMAR. There were six participants who already had a reading addition. Maximum reading speed ranged between 52 to 257 wpm (165 ± 61 wpm). Critical print size ranged between 0.325 to 1.403 logMAR (0.965 ± 0.279 logMAR). Repeated measures ANOVA on the whole group showed that there was a significant difference between the reading additions (p=0.001). The retinoscopy reading addition power was significantly lower than the age add (p=0.002) and the subjective add (p=0.038). Repeated measures ANOVA did not show any improvement of any of the reading measures with the reading additions compared to without the reading addition. A re-analysis was undertaken excluding participants who had normal accommodation at 12.5cm. The results of repeated measures ANOVA showed that there was no significant difference in the dioptric powers obtained by the three methods, although, all reading addition power were significantly greater than zero (t-test <0.0005). There was a significant difference in the area under the reading speed curve (p=0.035), which was greater with the subjective addition than with no reading addition (p=0.048). The MNREAD threshold significantly improved with the age addition compared to no addition (p=0.012). There was a large variability between the participants in their response to a reading addition. Analysis of individual data showed that some participants showed a clear improvement in reading performance with a reading addition. Other participants did not demonstrate any obvious improvement in reading performance with reading additions. Of those participants who showed an improvement, all but one participant had abnormal accommodation. However, not all participants who did not show an improvement had normal accommodation. Univariate analysis and forward step-wise linear regression analysis were used to investigate if any improvement in reading performance and the habitual reading performance without a reading addition could be predicted by factors that were measured in the study. These factors included distance visual acuity, near visual acuity, contrast sensitivity, lag of accommodation, age, time spent on reading each day, perceived difficulty of reading regular print and whether or not the participant received training for the usage of his/her low vision aids. Improvement in reading performance could not be predicted by any of these factors. Habitual reading performance without a reading addition was correlated with some factors. Univariate analysis showed that critical print size was associated with MNREAD threshold (r=0.904. p<0.0005), distance visual acuity (r=0.681, p<0.0005) and contrast sensitivity (r=-0.428, p=0.018) and MNREAD threshold without an addition was associated with the contrast sensitivity (r=-0.431, p=0.017,) and distance visual acuity (r=0.728, p<0.0005). Difficulty of reading correlated with near visual acuity (Spearman correlation coefficient=0.620, p=0.0009), MNREAD threshold (Spearman correlation coefficient=0.450, p=0.02) and maximum reading speed (Spearman correlation coefficient=-0.472, p=0.014). Time spent on reading each day correlated with the area under the reading speed curve (Spearman correlation coefficient=0.659, p=0.0024). The multiple regression analysis showed that MNREAD threshold was best predicted by distance visual acuity (R=0.728, p <0.0005), critical print size could be predicted by distance visual acuity (R=0.681, p <0.0005) and age (R=0.748, p=0.022) and the power of the subjective addition could be predicted by age (R=0.583, p=0.001) and near visual acuity (R=0.680, p=0.028). There was evidence that a reading addition improved reading performance as measured by the area under the curve and MNREAD (reading acuity) thresholds, but this was not predicted by any visual factor, except that all those who gained improvement had poor accommodation. Therefore, it is recommended that an eye care practitioner should demonstrate a reading addition in a low vision assessment of children and young adults, particularly with patients who have reduced accommodation.

Background: Worldwide one in twelve people are living with diabetes and one in two people do not know they have diabetes. Currently large numbers of the older people live in residential care homes in the UK, and up to one in four older people living in residential care homes present with diabetes. Low vision is one of the complications associated with diabetes in older people. In those aged 75 and over, one in five, and in those aged over 90, one in two people are affected by low vision and they are at an increased risk of developing other eye diseases. Within 20 years of diagnosis nearly all people with Type 1 and almost two thirds of people with Type 2 diabetes (60%) have some degree of diabetic retinopathy. Aims and Objectives: This study aimed to investigate the issues and problems faced by older people living in residential care homes with low vision and diabetes; to evaluate health professionals’ knowledge and understanding of the impact of low vision associated with diabetes in older people living in residential care homes; and to develop an educational toolkit which aimed to educate health care assistants about low vision and diabetes. Methods: This study is an exploratory investigation of older people living in residential care homes with low vision and diabetes. Adopting an open-ended qualitative approach using focus groups, interviews and a health professional’s survey, 116 participants were involved. These included GPs, ophthalmologists, nurses, optometrists, health care assistants and older people with low vision and diabetes. The data was analysed thematically. The educational toolkit was developed in the second part of this study, and 20 healthcare assistants were trained using this toolkit. Their knowledge was tested before the training, immediately after the training and one month after the initial training. Following Kirkpatrick’s model, the skills and practical use of the educational toolkit was assessed using an open-ended qualitative approach. Results: The results found that many older people and the health care assistants had the perception that low vision was a normal ageing process and could not be rectified. The study found that there was evidence to suggest that eye health was not considered to be a priority; instead, it was considered to be a natural part of the ageing process. The results found that 82% of the HCAs had not had any training in the area, and more than half of the nurses and GPs did not have sufficient knowledge of low vision and diabetes. After training, however, their knowledge was increased. This suggested that low vision and diabetes toolkit training could be used to educate healthcare assistants on a regular basis. The study also found that knowledge does decline over time, and therefore regular training for HCAs is required in order to maintain eye health and diabetes in older people, as well as improving their quality of life. Conclusion: In the research findings it was found that 50% to 70% of low vision was preventable or treatable if detected in its early stages and could be avoided by simply wearing appropriate spectacles, or possible surgery. However, in order to identify these 50% to 70% with low vision, everyone concerned should be able to recognise the signs and symptoms of preventable low vision, particularly health care assistants, as according to this study, health care assistants spent large amount of time in the residential care homes compared to the other health professionals.

Esta pesquisa tem por objetivo compreender como as cores podem influenciar na usabilidade das interfaces computacionais do usuário na web, pelo deficiente de baixa visão. Para tanto, principia com uma apresentação sobre a interface computacional do usuário, relacionando-a a interação humano-computador. São levantados os fenômenos da usabilidade envolvidos nesta interação, além da conceituação das cores e suas diferentes abordagens; sempre considerando o usuário de baixa visão. Em seguida é apresentado o deficiente de baixa visão, sua contextualização, suas características e necessidades. Com base nestas informações, inicia-se o processo de discussão em torno da inclusão através da web, trazendo para este universo, os deficientes em questão, as tecnologias assistivas e a acessibilidade. Após a fundamentação teórica é descrito como estudo de caso, um teste de usabilidade de interfaces web realizado com usuários de baixa visão a fim de gerar conhecimentos que permitam desenvolver um protótipo de interface tendo as cores como elemento principal. O protótipo desenvolvido é apresentado juntamente com o teste de usabilidade realizado com este, comprovando a contribuição das cores na usabilidade das interfaces web pelos usuários deficientes de baixa visão e respondendo ao problema desta pesquisa. Como resultado do trabalho realizado, é proposto e apresentado um modelo de cores para ser utilizado como referencial teórico na construção e readequação de interfaces computacionais de usuários de baixa visão, visando à usabilidade das interfaces na web. / The aim of this research is to understand how colors may influence the usability of computer interfaces on the web by low vision users. First, a presentation of the user computer interface is made, by comparing it to the human-computer interaction. Phenomena of the usability involved in this Interaction are elicited, as well as the conceptualization of colors and their different approaches, always taking into account the low vision user. After that, we discuss the low vision individuals, their contextualization, characteristics and needs. Based on this information, we begin the discussion about the inclusion through the web, bringing into that universe the target subjects of the present study, the disabled individuals, assistive technologies and accessibility. After the theoretical section, we describe a study case consisted of a web interfaces usability test with low vision individuals, which aimed to provide us with information that contributed for the development of an interface prototype which has colors as the principal aspect. The prototype developed is presented with the usability test conducted with it, showing the contribution of colors for the usability of web interfaces by users with low vision and answering to the problem and quest of this research. As a result of the work we have carried out, we propose and present a model of colors to be used as theoretical framework for the construction and improvement of computer interfaces by low vision users, aiming the usability of interfaces on the web.

Esta pesquisa tem por objetivo compreender como as cores podem influenciar na usabilidade das interfaces computacionais do usuário na web, pelo deficiente de baixa visão. Para tanto, principia com uma apresentação sobre a interface computacional do usuário, relacionando-a a interação humano-computador. São levantados os fenômenos da usabilidade envolvidos nesta interação, além da conceituação das cores e suas diferentes abordagens; sempre considerando o usuário de baixa visão. Em seguida é apresentado o deficiente de baixa visão, sua contextualização, suas características e necessidades. Com base nestas informações, inicia-se o processo de discussão em torno da inclusão através da web, trazendo para este universo, os deficientes em questão, as tecnologias assistivas e a acessibilidade. Após a fundamentação teórica é descrito como estudo de caso, um teste de usabilidade de interfaces web realizado com usuários de baixa visão a fim de gerar conhecimentos que permitam desenvolver um protótipo de interface tendo as cores como elemento principal. O protótipo desenvolvido é apresentado juntamente com o teste de usabilidade realizado com este, comprovando a contribuição das cores na usabilidade das interfaces web pelos usuários deficientes de baixa visão e respondendo ao problema desta pesquisa. Como resultado do trabalho realizado, é proposto e apresentado um modelo de cores para ser utilizado como referencial teórico na construção e readequação de interfaces computacionais de usuários de baixa visão, visando à usabilidade das interfaces na web. / The aim of this research is to understand how colors may influence the usability of computer interfaces on the web by low vision users. First, a presentation of the user computer interface is made, by comparing it to the human-computer interaction. Phenomena of the usability involved in this Interaction are elicited, as well as the conceptualization of colors and their different approaches, always taking into account the low vision user. After that, we discuss the low vision individuals, their contextualization, characteristics and needs. Based on this information, we begin the discussion about the inclusion through the web, bringing into that universe the target subjects of the present study, the disabled individuals, assistive technologies and accessibility. After the theoretical section, we describe a study case consisted of a web interfaces usability test with low vision individuals, which aimed to provide us with information that contributed for the development of an interface prototype which has colors as the principal aspect. The prototype developed is presented with the usability test conducted with it, showing the contribution of colors for the usability of web interfaces by users with low vision and answering to the problem and quest of this research. As a result of the work we have carried out, we propose and present a model of colors to be used as theoretical framework for the construction and improvement of computer interfaces by low vision users, aiming the usability of interfaces on the web.