**5. Terminological problems**

The term low vision was coined in the 1950s to convey the idea that vision can vary between the extremes of sighted and blindness [30]. Low vision generally refers to any chronic form of visual impairment that cannot be corrected with eye glasses, contact lenses, medical treatment or surgery and that negatively affects daily function of the individual [31, 32]. Although there is no universally accepted definition of "low vision," it is globally conceived as visual acuity of less than 0.3 (6/18) but equal or better than 0.05 (3/60) and/or visual field loss of less than 20 degrees in the better eye with the best possible correction [33].

This is based on the 10th revision of International Classification of Diseases derived from a World Health Organization Study group on the Prevention of Blindness that was convened in 1972 to provide a standardized definition to facilitate the data collection of population on prevalence of vision impairment and blindness.

Traditionally, low vision has been known by other numerous names such as partly sighted or subnormal vision, concepts that have already been outdated.

In 2002 at the 29th International Congress of Ophthalmology, the International Council of Ophthalmology (ICO) adopted a resolution where the following terminology was recommended [33, 34]:


### **6. Current situation and its problems**

Several research pieces have attempted to improve reading performance in people with central vision loss. Some authors have proposed to determine the mode of text

**85**

*Training Reading Skills in Central Field Loss Patients: Impact of Clinical Advances…*

presentation that offers these patients the fastest reading speed [35, 36] while others have suggested to examine whether simple manipulations of text typography or text typesetting (such as increasing letter or line spacing) could enhance this ability [37, 38]. Unfortunately, most of these studies did not found statistically significant differences in reading speed for different text presentations or when text typography

To date, only measures that have led to modest gains in reading speed among this group of people have been magnified font size, increased lighting and contrast conditions and the provision of optical magnifiers [39–41]. More recently, some works have established that reading performance on retinal periphery may benefits from perceptual learning based on certain tasks that include training in reading or identifying random letters sequences at various points across the visual field, although considerable individual variability was found in the results obtained from

As well as until the 1970s of the last century, people with low vision were rehabilitated as people with blindness, it is from that moment on that the magnification of texts and especially the use of optical and electronic aids allowed the development of the specific field of visual rehabilitation. The introduction of microscopes, magnifiers, telescopes and filters, together with the use of lecterns and adequacy of lighting, have allowed the development of a complete body of knowledge concerning to the new skills implemented when the person with CFL reads. The same can be said of electronic aids such as close-circuit television (CCTV) magnifiers and electronic magnifiers, which provide improved contrast and magnification that common optical aids of this type. These tools can be available mounted on a stand, head-mounted or hand-held.

As technological progress advances, numerous software apps and tech devices emerge to meet the reading needs of low-vision population. The production and distribution of digital documents was the beginning of harnessing technological advances for the visually impaired and brought new opportunities for reading improvement by allowing customization of lighting, contrast and font size variables

We are talking about software that magnify and provide contrast improvements or text to speech reproductions, compatible with computers and tablets, as well as the tablets and electronic books themselves, which thanks to the options they offer of brightness control, contrast, selection of type and font size, have been an important progress for people with AMD, and has enabled them to have free access to information. At present, high-tech digital image enhancement programs are under study to provide better visualization for central vision loss patients. They represent an important challenge due to the change of model that they offer in the intervention in visual rehabilitation. It is necessary at this point to expand the reach and depth of

A very relevant innovation is retinal implants; this is a prosthetic system that performs a process that captures the image, processes it and transforms it into electrical impulses and stimulates the retina's ganglion cells (RGCs) [45]. It appears to increase vision with acceptable safety profiles, even though the amelioration of functional vision generated by the prosthesis nowadays remains limited [46]. But it is still hopeful and promising in degenerative retinal diseases, and will surely bring

Comprehensive reading is a tremendously complex activity. Although for skillful readers, it is a task that does not seem to offer too many difficulties, and proof of this

research related to the use of these devices and software for reading.

a major challenge in the rehabilitation of these persons.

**7. Theory of reading performance**

*DOI: http://dx.doi.org/10.5772/intechopen.88943*

or text typesetting were modified.

these investigations [42, 43].

to optimize the text display on the screen [44].

#### *Training Reading Skills in Central Field Loss Patients: Impact of Clinical Advances… DOI: http://dx.doi.org/10.5772/intechopen.88943*

presentation that offers these patients the fastest reading speed [35, 36] while others have suggested to examine whether simple manipulations of text typography or text typesetting (such as increasing letter or line spacing) could enhance this ability [37, 38]. Unfortunately, most of these studies did not found statistically significant differences in reading speed for different text presentations or when text typography or text typesetting were modified.

To date, only measures that have led to modest gains in reading speed among this group of people have been magnified font size, increased lighting and contrast conditions and the provision of optical magnifiers [39–41]. More recently, some works have established that reading performance on retinal periphery may benefits from perceptual learning based on certain tasks that include training in reading or identifying random letters sequences at various points across the visual field, although considerable individual variability was found in the results obtained from these investigations [42, 43].

As well as until the 1970s of the last century, people with low vision were rehabilitated as people with blindness, it is from that moment on that the magnification of texts and especially the use of optical and electronic aids allowed the development of the specific field of visual rehabilitation. The introduction of microscopes, magnifiers, telescopes and filters, together with the use of lecterns and adequacy of lighting, have allowed the development of a complete body of knowledge concerning to the new skills implemented when the person with CFL reads. The same can be said of electronic aids such as close-circuit television (CCTV) magnifiers and electronic magnifiers, which provide improved contrast and magnification that common optical aids of this type. These tools can be available mounted on a stand, head-mounted or hand-held.

As technological progress advances, numerous software apps and tech devices emerge to meet the reading needs of low-vision population. The production and distribution of digital documents was the beginning of harnessing technological advances for the visually impaired and brought new opportunities for reading improvement by allowing customization of lighting, contrast and font size variables to optimize the text display on the screen [44].

We are talking about software that magnify and provide contrast improvements or text to speech reproductions, compatible with computers and tablets, as well as the tablets and electronic books themselves, which thanks to the options they offer of brightness control, contrast, selection of type and font size, have been an important progress for people with AMD, and has enabled them to have free access to information.

At present, high-tech digital image enhancement programs are under study to provide better visualization for central vision loss patients. They represent an important challenge due to the change of model that they offer in the intervention in visual rehabilitation. It is necessary at this point to expand the reach and depth of research related to the use of these devices and software for reading.

A very relevant innovation is retinal implants; this is a prosthetic system that performs a process that captures the image, processes it and transforms it into electrical impulses and stimulates the retina's ganglion cells (RGCs) [45]. It appears to increase vision with acceptable safety profiles, even though the amelioration of functional vision generated by the prosthesis nowadays remains limited [46]. But it is still hopeful and promising in degenerative retinal diseases, and will surely bring a major challenge in the rehabilitation of these persons.

## **7. Theory of reading performance**

Comprehensive reading is a tremendously complex activity. Although for skillful readers, it is a task that does not seem to offer too many difficulties, and proof of this

*Visual Impairment and Blindness - What We Know and What We Have to Know*

degrees in the better eye with the best possible correction [33].

The term low vision was coined in the 1950s to convey the idea that vision can vary between the extremes of sighted and blindness [30]. Low vision generally refers to any chronic form of visual impairment that cannot be corrected with eye glasses, contact lenses, medical treatment or surgery and that negatively affects daily function of the individual [31, 32]. Although there is no universally accepted definition of "low vision," it is globally conceived as visual acuity of less than 0.3 (6/18) but equal or better than 0.05 (3/60) and/or visual field loss of less than 20

This is based on the 10th revision of International Classification of Diseases derived from a World Health Organization Study group on the Prevention of

Blindness that was convened in 1972 to provide a standardized definition to facilitate the data collection of population on prevalence of vision impairment and blindness. Traditionally, low vision has been known by other numerous names such as partly sighted or subnormal vision, concepts that have already been outdated.

In 2002 at the 29th International Congress of Ophthalmology, the International Council of Ophthalmology (ICO) adopted a resolution where the following termi-

• Blindness: to be used exclusively for total vision loss and for conditions where

• Low vision: to be used for lesser degrees of vision loss, where individuals can

• Visual impairment: to be used when the condition of vision loss is characterized by a loss of visual functions, such as visual acuity or visual field, at the organ level since "impairment" is defined as any loss or abnormality of psychological, physiological or anatomical structure or function. Many of these functions (for example, visual acuity) can be measured quantitatively and in

• Visual disability: to be used when the condition prevents the undertaking of specific visual tasks, for example, loss of ability to read, since "disability" is defined as any restriction or lack resulting from an impairment of the ability to

perform an activity in a manner or within a range considered normal.

that individual (depending on age, sex and cultural factors).

applies to the individual and not to the visual system.

**6. Current situation and its problems**

• Visual handicap: to be used when the condition is described as a barrier to social participation (for example, loss of a driving license), since handicap is defined as a disadvantage for a given individual resulting from a disability or impairment that limits or prevents the fulfillment of a role that is normal for

• Functional vision: to be used when the vision loss is defined in terms of the individual's abilities with regard to activities of daily living (ADL). Thus, it

Several research pieces have attempted to improve reading performance in people with central vision loss. Some authors have proposed to determine the mode of text

individuals have to rely predominantly on vision substitution skills.

be helped significantly by vision enhancement aids and devices.

**5. Terminological problems**

nology was recommended [33, 34]:

each eye separately.

**84**

is the speed with which it is read (between 150 and 400 words per minute), the truth is that in such a short time several cognitive operations have to be carried out [47].

Reading is only possible if a good number of cognitive and visual operations function properly. It has been verified that the reading system is made up of several separable, relatively autonomous modules, each of which oversees carrying out a specific function. Specifically, four modules or processes are distinguished: perceptual processes, lexical processing, syntactic and semantic [48].

#### **7.1 Perceptual processes**

The first step for the reading is the perception of the text, the recognition of the word, opening here a question: is each letter identified separately or is the word identified in its entirety? Already in 1972, Gough found that it was easier to find or recognize a letter when it was part of a word than when it was isolated in a random series of letters [49]. On the other hand, it is possible that both theories have their share of reason and that using the letter or the global word as a processing unit depends on the task, the context, the characteristics of the word and the reader's skill [50]. Also, spacing is important in reading speed. It has been proved that increasing letter spacing has a negative effect on reading speed in experienced adult readers;

#### **Figure 2.**

*Orthographic representations in various theories of visual word processing of the words feed and food [52]. (a) Representation of letter identify and order theories. (b) Theory of grapheme identification. (c) Open bigram theory. (d) Separation of letter identity and letter doubling information theory (from https://link.springer. com/article/10.3758%2Fs13423-016-1149-8).*

**87**

*Training Reading Skills in Central Field Loss Patients: Impact of Clinical Advances…*

while in children has no effect [51]. On the other hand, Fischer-Baum researched word identification, taking special focus on double letters [52]. He also noticed that a patient with acquired dyslexia used to spell words in a similar way as a previous spelt word, including double letters [53]. He found that letter identity and double letters are separately represented in written language, showing a complex reading capacity and a common orthographic representation of reading and writing (**Figure 2**).

Eye movements and fixations are involved in the perceptual process. The information we extract passes into iconic memory, of great capacity but short duration. The information is transferred from iconic memory to short-term visual memory, which allows it to be maintained for a longer period of time and is now retained as linguistic material. Finally, a comparison is made with the long-term memory to

The next step is the recognition of the meaning of the word, a process that can be done in two ways. One of them is to compare the spelling of the word with a series of representations stored in the memory to see which one fits. All that is needed is the existence of a word store or mental lexicon in which all the words known to the reader are represented [53]. Reading by this route involves several operations: the visual analysis of the word that is transmitted to a store of orthographic representations of words called "visual lexicon", where it is identified by comparison with the units stored there. This in turn will activate the corresponding phonological representation, located in another lexical warehouse, the so-called "phonological lexicon", and from here it will be deposited in the "pronunciation warehouse" ready to be issued. This route is known by the name of lexical route or also visual route [53].

We talk about the process of understanding how words are interrelate to each other. Isolated words do not convey any new information, but it is in the relationship between them that the message is found [54]. Once the words of a sentence have been recognized the reader must determine how they are related to each other. The parsing process therefore comprises three main operations [55], by means of which the areas to which the words correspond are labeled, the relationship between the components is established and a structure is constructed according to

In this process, once the meaning of the sentence has been extracted, it is integrated and compared with previous knowledge; therefore, the richness of the person's vocabulary and previous experience will be decisive. The process ends when extracted meaning is integrated into memory, with the rest of the reader's knowledge. During this process, the reader makes certain inferences, makes deductions about the information and adds non-explicit information. This last phase of the process is the most complex but it is not carried out independently of the

When assessing reading comprehension, sometimes independent phrases are used, outside of a story or context. If there are no given part, the sentences could not be understood as we do not know what facts they refer to. If, on the other hand, there are no new parts, they would not provide any knowledge other than that

previous ones, but all the processes interact with each other [47].

*DOI: http://dx.doi.org/10.5772/intechopen.88943*

check whether the word is stored [47].

**7.2 Lexical processing**

**7.3 Syntactic processing**

the hierarchy of its components.

which is already possessed [49].

**7.4 Semantic processing**

*Training Reading Skills in Central Field Loss Patients: Impact of Clinical Advances… DOI: http://dx.doi.org/10.5772/intechopen.88943*

while in children has no effect [51]. On the other hand, Fischer-Baum researched word identification, taking special focus on double letters [52]. He also noticed that a patient with acquired dyslexia used to spell words in a similar way as a previous spelt word, including double letters [53]. He found that letter identity and double letters are separately represented in written language, showing a complex reading capacity and a common orthographic representation of reading and writing (**Figure 2**).

Eye movements and fixations are involved in the perceptual process. The information we extract passes into iconic memory, of great capacity but short duration. The information is transferred from iconic memory to short-term visual memory, which allows it to be maintained for a longer period of time and is now retained as linguistic material. Finally, a comparison is made with the long-term memory to check whether the word is stored [47].

#### **7.2 Lexical processing**

*Visual Impairment and Blindness - What We Know and What We Have to Know*

tual processes, lexical processing, syntactic and semantic [48].

**7.1 Perceptual processes**

is the speed with which it is read (between 150 and 400 words per minute), the truth is that in such a short time several cognitive operations have to be carried out [47]. Reading is only possible if a good number of cognitive and visual operations function properly. It has been verified that the reading system is made up of several separable, relatively autonomous modules, each of which oversees carrying out a specific function. Specifically, four modules or processes are distinguished: percep-

The first step for the reading is the perception of the text, the recognition of the word, opening here a question: is each letter identified separately or is the word identified in its entirety? Already in 1972, Gough found that it was easier to find or recognize a letter when it was part of a word than when it was isolated in a random series of letters [49]. On the other hand, it is possible that both theories have their share of reason and that using the letter or the global word as a processing unit depends on the task, the context, the characteristics of the word and the reader's skill [50]. Also, spacing is important in reading speed. It has been proved that increasing letter spacing has a negative effect on reading speed in experienced adult readers;

*Orthographic representations in various theories of visual word processing of the words feed and food [52]. (a) Representation of letter identify and order theories. (b) Theory of grapheme identification. (c) Open bigram theory. (d) Separation of letter identity and letter doubling information theory (from https://link.springer.*

**86**

**Figure 2.**

*com/article/10.3758%2Fs13423-016-1149-8).*

The next step is the recognition of the meaning of the word, a process that can be done in two ways. One of them is to compare the spelling of the word with a series of representations stored in the memory to see which one fits. All that is needed is the existence of a word store or mental lexicon in which all the words known to the reader are represented [53]. Reading by this route involves several operations: the visual analysis of the word that is transmitted to a store of orthographic representations of words called "visual lexicon", where it is identified by comparison with the units stored there. This in turn will activate the corresponding phonological representation, located in another lexical warehouse, the so-called "phonological lexicon", and from here it will be deposited in the "pronunciation warehouse" ready to be issued. This route is known by the name of lexical route or also visual route [53].

#### **7.3 Syntactic processing**

We talk about the process of understanding how words are interrelate to each other. Isolated words do not convey any new information, but it is in the relationship between them that the message is found [54]. Once the words of a sentence have been recognized the reader must determine how they are related to each other. The parsing process therefore comprises three main operations [55], by means of which the areas to which the words correspond are labeled, the relationship between the components is established and a structure is constructed according to the hierarchy of its components.

#### **7.4 Semantic processing**

In this process, once the meaning of the sentence has been extracted, it is integrated and compared with previous knowledge; therefore, the richness of the person's vocabulary and previous experience will be decisive. The process ends when extracted meaning is integrated into memory, with the rest of the reader's knowledge. During this process, the reader makes certain inferences, makes deductions about the information and adds non-explicit information. This last phase of the process is the most complex but it is not carried out independently of the previous ones, but all the processes interact with each other [47].

When assessing reading comprehension, sometimes independent phrases are used, outside of a story or context. If there are no given part, the sentences could not be understood as we do not know what facts they refer to. If, on the other hand, there are no new parts, they would not provide any knowledge other than that which is already possessed [49].
