**Abstract**

The primary goal of patients with central field loss attending to visual rehabilitation (VR) offices is to get adapted to daily life activities in near vision, mainly looking for recovering their ability to read again. The disparity in the functionality of these patients, due to the new advances in medical treatment and the increasing number of new apps and technological devices in the market, implies a heterogeneity in the reading training programs to be applied, and consequently a variability in the results obtained. Currently, with the increasing access to information and communication technologies and social networks, the opportunities for improving their access to information and communication is taken an important role. For this reason, the basis of ad-hoc evidence-based reading training programs is needed to standardized the clinical practice in reading rehabilitation for visual impaired and blind patients. This chapter will go in depth into these topics offering an exhaustive state of the art of reading rehabilitation for central field loss patients that will be useful for clinicians dedicated to the rehabilitation of visual impaired and blind people.

**Keywords:** visual rehabilitation, age-related macular degeneration, central field loss, eccentric fixation, saccades, optical aids, reading training, reading speed

### **1. Introduction**

Reading is an extraordinarily sophisticated task that involves the synthesis of a number of different motor, sensory and cognitive functions [1]. Its proper performance largely depends on the state of the macula lutea and the optical pathway and visual cortex. Conditions affecting these areas such as age-related macular degeneration (AMD) and acquired brain injury (ABI) are frequent in the elderly and can compromise the reception or the conduction and processing of central visual information, with the consequent impairment of this ability, of great importance for the vocational, educational and daily life of the individual. Consequently, in low vision rehabilitation services, reading is the most common clinical complaint, as well as

the primary goal for patients with central vision loss [1–3], whose prevalence is expected to increase in the coming years, as well as the diseases continues to rise in line with the aging of the population. Thus, improvement of reading performance in central vision loss patients is nowadays considered as one of the main objectives pursued by neuro-vision rehabilitation (NVR).

When the vision in the center of the visual field decreases, reading speed declines and oculomotor pattern differs compared with normal reading, showing an increase in the mean fixation duration and in the number of saccades [4, 5]. It is known that many of these individuals may eventually adopt one or more locations on the retinal periphery to serve as the preferred retinal locus (PRL). Therefore, for these patients, visual function is still malleable and able to adapt to unfavorable conditions [6, 7].

## **2. Development of visual rehabilitation and training in brief**

When you hear the word blind or low vision, Braille system and the inability for the person to perform everyday tasks such as moving around comes to your mind [7].

If we trace a low vision timeline backwards in history, we can find that it is known that Marco Polo discovers elderly Chinese people using magnifying glasses for Reading (1270), and the first magnifying aid for visual defects attributed to Rene Descartes in 1637 [8]; But it is not until the nineteenth century that the LVR receives attention. In 1850, Amsterdam separately counts the number of inhabitants with impaired vision, Hermann von Helmholtz invents the ophthalmoscope (1851) and, in 1897, Charles Prentice invents the typoscope [8]. The beginnings of the current era can be said to have begun at the first international congress in low vision, sponsored by the American Foundation for the Blind, in 1986. In 1996, International Society for Low-vision Research and Rehabilitation (ISLRR) officially incorporated in Amsterdam [8]. By the mid-twentieth century, the first manuals including information on methods of visual rehabilitation were published. E. Faye was the first person to coin the term low vision.

In 1973, the first Low Vision Diplomate program established was registered within American Academy of Optometry first diplomate awarded Western Michigan University (USA) offers first required low vision course as part of orientation & mobility program Low Vision Clinical Society founded in the United States [8].

Currently, a person with distant visual acuity (VA) 0.3 or less (20/60 Snellen notation), a visual field of 10° from the point of fixation, and with reduced functionality is considered low vision [7]. This definition was not always universal, previously low vision was defined by a VA of 20/70 or less, however, it did not include the degree of functional defect. The subject's functionality may be affected (even in VAs greater than 20/70) by problems of loss of contrast sensitivity (CS) and glare [9].

In 2018, the International Classification of Diseases separated visual impairment into two groups: far and near. Thus, the near vision impairment is an VA lower than N6 or N8 at 40 cm with the existing correction. There are signs that worldwide the World Health Organization estimates that there are 1300 million people with visual impairment [10].

It should be noted that visual rehabilitation requires multidisciplinary work, which includes ophthalmologists, optometrists and visual therapists, in most cases psychologists and social workers work together.

The work of psychologists is important in those patients who are in a state of depression. Depression can be detected by optometrists or ophthalmologists through anamnesis and the use of questionnaires. Studies have found that people with vision loss have four times more depression than a person without visual

**81**

or in a public building.

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

impairment [11]. One of the main objectives of the visual rehabilitation service is to improve the functional capacity of each subject and the action plan must be adapted

Visual rehabilitation, apart from improving the quality of life of subjects by increasing their functionality, avoids a series of events that can be triggered by their visual impairment. Among the events are: falls, being people with low vision more likely to suffer [13] and depression, which more than 30% of these subjects develop

Visual rehabilitation seeks to regain the skills of a person with visual impairment. This recovery is done gradually, using optical and non-optical aids, in addition to the strategies proposed by the visual therapist. The action of reading necessarily implies using the central retina. Therefore, a visual disability due to an ophthalmological pathology that affects the central visual field will significantly

Several studies indicate that reading is one of the most important actions that visually impaired people want to recover [15, 16]. This task is usually the main

Being referred to low vision service implies a loss of vision that can generate loss of functionality, and consequently the subject may be perceived as not very competent, which will influence his mental state. Such a state can influence the outcome of rehabilitation, which in turn can contribute to changing the way in which the

Every time we read, the eyes perform a sequence of movements. The ocular movements by which these jump from one stimulus to another are called *saccadic* movements. Normally in the reading process, they go from left to right, but sometimes there are movements in the opposite direction to change lines or to return to

We call *fixation* to the pause between a saccadic movement and another, in which moment the information is extracted. The amount and duration of this fixation calculates the reading capacity of the subject. The reading speed serves to evaluate the reading ability of the subject; in a subject in normal vision, recognize from 7 to 11 characters in the fovea during fixation in the right half but four or five characters in the left half. In other words, it is called *visual span* to the number of

In a subject with low vision restoring its functionality and independence has a lot of meaning. Reading is also important for those children or adolescents who suffer from low vision, these subjects need to continue schooling or simply enjoy reading as a leisure, remaining functional, independent and psychologically motivated. Our world has been designed for the reader, for those people who are able to interpret all the information that surrounds us. Reading is an activity that affects all the orders of daily life, from access to the content of a letter or a medicine label, to the buy of a product or the information that we can find in the street

what was read, in which case they are called *regression* movements [17].

letters that can be recognized without moving the eyes [17].

**3.2 How does reading performance work in AMD patients?**

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

and show an improvement in VR by eliminating it [14].

**3. Reading as one of the objectives of visual rehabilitation**

objective in the elderly, children and adolescents with low vision.

individually [12].

affect to the action of reading.

subject views himself.

**3.1 How do we read?**

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

impairment [11]. One of the main objectives of the visual rehabilitation service is to improve the functional capacity of each subject and the action plan must be adapted individually [12].

Visual rehabilitation, apart from improving the quality of life of subjects by increasing their functionality, avoids a series of events that can be triggered by their visual impairment. Among the events are: falls, being people with low vision more likely to suffer [13] and depression, which more than 30% of these subjects develop and show an improvement in VR by eliminating it [14].

## **3. Reading as one of the objectives of visual rehabilitation**

Visual rehabilitation seeks to regain the skills of a person with visual impairment. This recovery is done gradually, using optical and non-optical aids, in addition to the strategies proposed by the visual therapist. The action of reading necessarily implies using the central retina. Therefore, a visual disability due to an ophthalmological pathology that affects the central visual field will significantly affect to the action of reading.

Several studies indicate that reading is one of the most important actions that visually impaired people want to recover [15, 16]. This task is usually the main objective in the elderly, children and adolescents with low vision.

Being referred to low vision service implies a loss of vision that can generate loss of functionality, and consequently the subject may be perceived as not very competent, which will influence his mental state. Such a state can influence the outcome of rehabilitation, which in turn can contribute to changing the way in which the subject views himself.

#### **3.1 How do we read?**

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

**2. Development of visual rehabilitation and training in brief**

pursued by neuro-vision rehabilitation (NVR).

was the first person to coin the term low vision.

psychologists and social workers work together.

the primary goal for patients with central vision loss [1–3], whose prevalence is expected to increase in the coming years, as well as the diseases continues to rise in line with the aging of the population. Thus, improvement of reading performance in central vision loss patients is nowadays considered as one of the main objectives

When the vision in the center of the visual field decreases, reading speed declines and oculomotor pattern differs compared with normal reading, showing an increase in the mean fixation duration and in the number of saccades [4, 5]. It is known that many of these individuals may eventually adopt one or more locations on the retinal periphery to serve as the preferred retinal locus (PRL). Therefore, for these patients, visual function is still malleable and able to adapt to unfavorable conditions [6, 7].

When you hear the word blind or low vision, Braille system and the inability for the person to perform everyday tasks such as moving around comes to your mind [7]. If we trace a low vision timeline backwards in history, we can find that it is known that Marco Polo discovers elderly Chinese people using magnifying glasses for Reading (1270), and the first magnifying aid for visual defects attributed to Rene Descartes in 1637 [8]; But it is not until the nineteenth century that the LVR receives attention. In 1850, Amsterdam separately counts the number of inhabitants with impaired vision, Hermann von Helmholtz invents the ophthalmoscope (1851) and, in 1897, Charles Prentice invents the typoscope [8]. The beginnings of the current era can be said to have begun at the first international congress in low vision, sponsored by the American Foundation for the Blind, in 1986. In 1996, International Society for Low-vision Research and Rehabilitation (ISLRR) officially incorporated in Amsterdam [8]. By the mid-twentieth century, the first manuals including information on methods of visual rehabilitation were published. E. Faye

In 1973, the first Low Vision Diplomate program established was registered within American Academy of Optometry first diplomate awarded Western Michigan University (USA) offers first required low vision course as part of orientation & mobility program Low Vision Clinical Society founded in the United States [8]. Currently, a person with distant visual acuity (VA) 0.3 or less (20/60 Snellen notation), a visual field of 10° from the point of fixation, and with reduced functionality is considered low vision [7]. This definition was not always universal, previously low vision was defined by a VA of 20/70 or less, however, it did not include the degree of functional defect. The subject's functionality may be affected (even in VAs greater than 20/70) by problems of loss of contrast sensitivity (CS)

In 2018, the International Classification of Diseases separated visual impairment into two groups: far and near. Thus, the near vision impairment is an VA lower than N6 or N8 at 40 cm with the existing correction. There are signs that worldwide the World Health Organization estimates that there are 1300 million people with visual

It should be noted that visual rehabilitation requires multidisciplinary work, which includes ophthalmologists, optometrists and visual therapists, in most cases

The work of psychologists is important in those patients who are in a state of depression. Depression can be detected by optometrists or ophthalmologists through anamnesis and the use of questionnaires. Studies have found that people with vision loss have four times more depression than a person without visual

**80**

and glare [9].

impairment [10].

Every time we read, the eyes perform a sequence of movements. The ocular movements by which these jump from one stimulus to another are called *saccadic* movements. Normally in the reading process, they go from left to right, but sometimes there are movements in the opposite direction to change lines or to return to what was read, in which case they are called *regression* movements [17].

We call *fixation* to the pause between a saccadic movement and another, in which moment the information is extracted. The amount and duration of this fixation calculates the reading capacity of the subject. The reading speed serves to evaluate the reading ability of the subject; in a subject in normal vision, recognize from 7 to 11 characters in the fovea during fixation in the right half but four or five characters in the left half. In other words, it is called *visual span* to the number of letters that can be recognized without moving the eyes [17].

#### **3.2 How does reading performance work in AMD patients?**

In a subject with low vision restoring its functionality and independence has a lot of meaning. Reading is also important for those children or adolescents who suffer from low vision, these subjects need to continue schooling or simply enjoy reading as a leisure, remaining functional, independent and psychologically motivated. Our world has been designed for the reader, for those people who are able to interpret all the information that surrounds us. Reading is an activity that affects all the orders of daily life, from access to the content of a letter or a medicine label, to the buy of a product or the information that we can find in the street or in a public building.

The Johns Hopkins Wilmer Eye Institute study showed that 60% of patients referred to low vision report that the main reason for consultation is the difficulty to read, other studies such as, see [18, 19] give similar results. There are also studies on age-related macular degeneration (AMD), the most common pathology that causes severe disability in the western world, where they mention the increase in emotional state, cognitive and quality of life of patients by improving the speed of reading [20].

When a person cannot use the fovea, all eye movements involved in the reading process are affected and as a consequence performance decreases considerably; other daily activities are also affected. Understanding that there are ophthalmological pathologies that affect the central field of vision, it is necessary to use the peripheral retina. Subjects use a region of para-central retina, normally less than 20° from the damage fovea [21]. This retinal place to use is known as preferential retinal locus (PRL). This PRL gives the ability to perform the function of the damaged central retinal area, can be trained and used for activities such as reading. In short, it is necessary to evaluate the PRL, know its location, characteristics (a microperimeter offers a precise method for this action) and from then on use optical and non-optical aids to rehabilitate the reading. Studies show that the use of microperimetry for rehabilitation generates improvements in visual acuity, fixation stability and reading speed.

When central field loss (CFL) is present, saccadic movements are erratic, with constant regression movements; fixation is very unstable and, as a consequence, perceived information is scarce and partial. All this affects two fundamental aspects for a satisfactory reading: reading speed and reading comprehension. In order to assess reading ability, these aspects must be measured. One of the goals of visual rehabilitation is to help the subject establish their own PRL as well as learn to use it efficiently. Sometimes the person has more than one PRL, and may even use it consciously or unconsciously.

Other aspects that affect the reading process and are involved in rehabilitation are the effect of crowding, which together with the visual span, present a correlation that is clarifying; reducing crowding enlarge the visual span and can facilitate reading [22].

#### **4. Medical and technological advances for patients with central field loss**

#### **4.1 Central field loss pathologies**

Central field loss is associated with macular diseases. Examples of these diseases are age-related macular degeneration, macular hole, macular edema and diabetic retinopathy [23]. In general, patients with these pathologies have preserved peripheral vision. As central vision is affected, reading or face recognition are affected. Rehabilitation strategies and visual aids are focused on those tasks.

#### **4.2 Therapeutic strategies**

In atrophic diseases, there is not a specific treatment, so actions are directed to prevention and in advanced cases, rehabilitation. In exudative diseases such as exudative AMD, there has been a wide range of treatments, including laser, radiation and anti- vascular endothelial growth factor (VEGF) therapy [24].

Laser photocoagulation was the first treatment for exudative AMD from 1979 [24]. This treatment stopped neovascularization progression, but laser burned retinal

**83**

**Figure 1.**

*articles/PMC4478143/).*

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

tissue, so patients with macular neovascularization could not be treated [24, 25]. This technique consisted in impacting with a laser on the retina to produce heat and that the proteins coagulate in order to slow down the appearance of neovases [26].

Another therapeutic strategy is radiation. This procedure attempts to affect the angiogenesis of choroidal neovases either directly by destroying endothelial cells and cytokines or indirectly on genes that regulate the action of cytokines. It can be administered by brachytherapy directly on the affected tissue; or by teletherapy administering the isotope externally [24]. It can be combined with anti-VEGF

With photodynamic therapy a photosensitive substance is injected in vein in order to activate it with a laser at a choroidal vessels level. In 1999, the efficacy of photodynamic therapy to stop choroidal neovascularization was tested, as well as the maximum and minimum doses to achieve the desired effect, being 150 and 25 J/

Repeated intravitreal injections of anti-VEGF drugs are currently the most widely used treatment in AMD. VEGF is an angiogenic and vasculogenic factor; that is, it is involved in the formation of new vessels from existing ones and in the formation of embryonic vessels; as well as in their reappearance [28]. Several drugs had been developed, such as pegaptanib, bevacizumab, ranibizumab and, recently aflibercept. However, these anti-VEGF drugs only are trying to slow down the

**4.3 Optical coherence tomography (OCT): advances in screening technology**

*An example of the nine analysis areas of macular cube strategy (from https://www.ncbi.nlm.nih.gov/pmc/*

OCT is a diagnostic and control technology based on the principle of Michelson interferometry whereby light is divided into two optical pathways to the eye and a mirror. Thanks to this we can analyze the posterior retina, the macula, the papilla and the relations they have with the vitreous and the choroid [29]. The OCT Macular Cube 512 × 128 strategy allows, in addition to the analysis of macular layers, comparison with different measures in the same patient and comparison with the OCT database to establish whether the values are within normal or not, analyzing the macula in nine areas, being a central and two rings with four layers each (**Figure 1**). By means of this strategy, an area of 6 × 6 mm is measured using

progression, they are not able to reverse the effect of the disease [25].

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

therapy [27].

, respectively [24].

128 A-Scans with 512 B-Scans.

cm2

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

tissue, so patients with macular neovascularization could not be treated [24, 25]. This technique consisted in impacting with a laser on the retina to produce heat and that the proteins coagulate in order to slow down the appearance of neovases [26].

Another therapeutic strategy is radiation. This procedure attempts to affect the angiogenesis of choroidal neovases either directly by destroying endothelial cells and cytokines or indirectly on genes that regulate the action of cytokines. It can be administered by brachytherapy directly on the affected tissue; or by teletherapy administering the isotope externally [24]. It can be combined with anti-VEGF therapy [27].

With photodynamic therapy a photosensitive substance is injected in vein in order to activate it with a laser at a choroidal vessels level. In 1999, the efficacy of photodynamic therapy to stop choroidal neovascularization was tested, as well as the maximum and minimum doses to achieve the desired effect, being 150 and 25 J/ cm2 , respectively [24].

Repeated intravitreal injections of anti-VEGF drugs are currently the most widely used treatment in AMD. VEGF is an angiogenic and vasculogenic factor; that is, it is involved in the formation of new vessels from existing ones and in the formation of embryonic vessels; as well as in their reappearance [28]. Several drugs had been developed, such as pegaptanib, bevacizumab, ranibizumab and, recently aflibercept. However, these anti-VEGF drugs only are trying to slow down the progression, they are not able to reverse the effect of the disease [25].

#### **4.3 Optical coherence tomography (OCT): advances in screening technology**

OCT is a diagnostic and control technology based on the principle of Michelson interferometry whereby light is divided into two optical pathways to the eye and a mirror. Thanks to this we can analyze the posterior retina, the macula, the papilla and the relations they have with the vitreous and the choroid [29]. The OCT Macular Cube 512 × 128 strategy allows, in addition to the analysis of macular layers, comparison with different measures in the same patient and comparison with the OCT database to establish whether the values are within normal or not, analyzing the macula in nine areas, being a central and two rings with four layers each (**Figure 1**). By means of this strategy, an area of 6 × 6 mm is measured using 128 A-Scans with 512 B-Scans.

#### **Figure 1.**

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

reading [20].

stability and reading speed.

consciously or unconsciously.

**4.1 Central field loss pathologies**

**4.2 Therapeutic strategies**

reading [22].

The Johns Hopkins Wilmer Eye Institute study showed that 60% of patients referred to low vision report that the main reason for consultation is the difficulty to read, other studies such as, see [18, 19] give similar results. There are also studies on age-related macular degeneration (AMD), the most common pathology that causes severe disability in the western world, where they mention the increase in emotional state, cognitive and quality of life of patients by improving the speed of

When a person cannot use the fovea, all eye movements involved in the reading process are affected and as a consequence performance decreases considerably; other daily activities are also affected. Understanding that there are ophthalmological pathologies that affect the central field of vision, it is necessary to use the peripheral retina. Subjects use a region of para-central retina, normally less than 20° from the damage fovea [21]. This retinal place to use is known as preferential retinal locus (PRL). This PRL gives the ability to perform the function of the damaged central retinal area, can be trained and used for activities such as reading. In short, it is necessary to evaluate the PRL, know its location, characteristics (a microperimeter offers a precise method for this action) and from then on use optical and non-optical aids to rehabilitate the reading. Studies show that the use of microperimetry for rehabilitation generates improvements in visual acuity, fixation

When central field loss (CFL) is present, saccadic movements are erratic, with constant regression movements; fixation is very unstable and, as a consequence, perceived information is scarce and partial. All this affects two fundamental aspects for a satisfactory reading: reading speed and reading comprehension. In order to assess reading ability, these aspects must be measured. One of the goals of visual rehabilitation is to help the subject establish their own PRL as well as learn to use it efficiently. Sometimes the person has more than one PRL, and may even use it

Other aspects that affect the reading process and are involved in rehabilitation are the effect of crowding, which together with the visual span, present a correlation that is clarifying; reducing crowding enlarge the visual span and can facilitate

**4. Medical and technological advances for patients with central field loss**

Central field loss is associated with macular diseases. Examples of these diseases are age-related macular degeneration, macular hole, macular edema and diabetic retinopathy [23]. In general, patients with these pathologies have preserved peripheral vision. As central vision is affected, reading or face recognition are affected.

In atrophic diseases, there is not a specific treatment, so actions are directed to prevention and in advanced cases, rehabilitation. In exudative diseases such as exudative AMD, there has been a wide range of treatments, including laser, radia-

Laser photocoagulation was the first treatment for exudative AMD from 1979 [24]. This treatment stopped neovascularization progression, but laser burned retinal

Rehabilitation strategies and visual aids are focused on those tasks.

tion and anti- vascular endothelial growth factor (VEGF) therapy [24].

**82**

*An example of the nine analysis areas of macular cube strategy (from https://www.ncbi.nlm.nih.gov/pmc/ articles/PMC4478143/).*
