Background and Objectives: In a digital library what provides interaction between user and library is user interface. Tedd and Hartley (1999) declared, “User interface is a bridge which relates the users with storage and retrieval systems”. Good user interface should be used to establish effective interaction between users and digital libraries to help them to use and access desired information resources effectively. A user interface allows the users to obtain ‘what they need, in a desired way and in a user friendly manner’ (ibid). It should be prepared and designed according to the information needs of their user community (in this case, blind and visually impaired). Since blind and visually impaired have specific behaviors and cognitive characteristics, so interfaces should be designed carefully and enriched with the capabilities so that these users will be able to use them with ease and comfort. Blind and visually impaired, like the other users, need to interact with interfaces for access to information resources in a digital environment.
Therefore, it would be very important to present a set of criteria for user interfaces in Blind and visually impaired digital libraries. Therefore, this study intends to investigate and determine the most important criteria blind and visually impaired digital libraries user interface from the experts’ point of view about these criteria and recommend a sample set of criteria for digital Libraries providers' services to the blind and visually impaired user interfaces. This is the basic question that the research tries to answer is: What are the important of evaluation criteria in digital Libraries providers' services to the blind and visually impaired user interface from experts’ point of view Librarians Attitude at blind digital libraries in Iran?
Methodology: The present study used survey as the methodology which is done in two sections. In first section through the reviewing the related scientific texts and resources, the researchers prepared a checklist consisting of 13 criteria (Different formats of library resources, Ability of organizing the screen, Study services of retrieved resources from the library, Error messages alert, Options for customizing the texts, Language User Interface, Interaction and feedback facilities, Links, Help services and tips, Search facilities, Visual symbols and images, user control, Screen capabilities) and 109 components. The results were evaluated according to these 13 criteria in response to research questions. In the second section of this Research, a two-step Delphi method was used. For this purpose, final checklist was emailed to a 10 librarian's attitude at blind digital libraries in Iran to gather their opinion about the importance of each criterion. SPSS and Excel software are used to analyses data. Finally, median score was performed as an evaluation device for acceptance or rejection of a criterion. Those criteria which obtained medium score higher than 3(60 percent), were accepted as an element to be included in the proposed criteria for digital Libraries providers' services to the blind and visually impaired user interface.
Findings: This survey sought Librarians attitude at blind digital libraries point of view and selected set of criteria is proposed for the digital Libraries providers' services to the blind and visually impaired user interface. The findings of the survey are presented in the following section. Importance of each criterion from the Librarians attitude at blind digital libraries point of view: Experts were asked of their opinion about the degree of importance of each criterion. The results of their response are showed in Table1.
As the Table 1 shows, it was found that among the criteria, the respondents gave the highest rating to «Different formats of library resources» (mean Medium-Score = 4.99) and the lowest to «Screen capabilities» (mean Medium-Score = 4.44). Two other criteria i.e. «Ability of organizing the screen» and «Study services of retrieved resources from the library» reached the second and third levels, respectively. Although the difference among of criteria's were low and according to the Delphi panel using them in the design of digital Libraries providers' services to the blind and visually impaired user interface offered. Also, Friedman test was used to determine the priority indicators. The zero assumption does not differentiate between the importance of existing criteria for use in the user interface of digital libraries providing services to blind and visually impaired users. The results of the Friedman test indicate the obtained sig is .000 and less than 0.05. This indicate that the zero assumption is rejected and there is a research hypothesis that there is a significant difference between the most important criteria for assessing the user interface of digital libraries providing services to visually impaired and blind people. As a result, it can be said that the importance of each user interface criteria is not the same for evaluation and the custodians and designers of digital Libraries providers' services to the blind and visually impaired user interface can be considered conception, planning and implementation of user interface features according to the budget, time and needs of their users.
Discussion:  The aim of this research is to consider and determine the most important criteria of user interface of Digital Libraries providers' services to the blind and visually impaired from the point of view of librarian’s attitude at blind digital libraries. Although various studies have discussed how to provide services to users with visual impairment and interaction with libraries, but it is necessary to provide criteria for interaction between the library and the blind and visually impaired users in the point of view of librarian’s attitude at blind digital libraries (because they interact directly with visually impaired users). These can be used to design, evaluate, and improve the user interface of the digital Libraries providers' services to the blind and visually impaired user interface. From the librarian’s attitude at blind digital libraries point of view, the «Different formats of library resources» (mean Medium-Score = 4.99) and «Screen capabilities» (mean Medium-Score = 4.44) criteria reached the highest and lowest scores, respectively. Blind and visually impaired users have problems in the use of common resources. Therefore, it is necessary to provide other formats of resources such as illustrative books, audio resources and etc. for these users. Obtaining the first rank in librarians' point of view can also be confirmed by the importance of resources for users of digital libraries provider`s services to the blind and visually impaired. A screen capability reached thirteenth level and is located bottom of the rating table. It is general features of database and web pages and gets the thirteenth place of the Delphi panel as well. Finally, it can be said that environment information exchange systems user interface such as digital libraries is so complicated and its goal is to provide remote services for users. Since blind and visually impaired users have specific behaviors and cognitive characteristics, and the deleted of the human interface in digital libraries, so interfaces should be designed carefully and enriched with the capabilities so that blind and visually impaired users will be able to use them with ease and comfort. All of the criteria in this study will be applicable to the digital Libraries providers' services to the blind and visually impaired user interface. On the other hand, it could be used as a tool for the determination of capabilities of digital Libraries providers' services to the blind and visually impaired user interface from librarians, experts and their user's opinion. The results of this study can be considered as a beginning effort for developing standard criteria for blind and visually impaired libraries in order to increase the quality and quantity of their user interfaces.