The use of optical devices in school- children with low vision due to congenital glaucoma

The use of optical devices in school-age children with low vision due to congenital glaucoma

School Years: Low vision

Maria Aparecida Onuki Haddad, Marcos Wilson Sampaio, Ernst Oltrogge, Alberto Jorge Betinjane, Newton Kara-José.

Maria Aparecida Onuki Haddad MD

Ophtalmologist

Laramara - Brazilian Association for Assistance for people with visual impairment

Low Vision Service

Department of Ophthalmology

University of São Paulo Clinical Hospital

São Paulo - SP

Rua Apeninos, 990 ap 81

CEP 04104-020

Brazil

55-11-55732744 36606453

onhaddad@ifxbrasil.com.br

According to the 10th revision of the International Classification of Illnesses and Health-related Problems, a person is considered to have low vision when visual acuity with correction in the best eye falls between 6/18 and 3/60 (categories 1 and 2 of the degree of visual impairment) and is considered to be blind when these values lie below 3/60 (categories 3, 4 and 5)6. In 1992 the World Health Organization (WHO) proposed the functional definition of low vision: a person with low vision is one who has impairment of visual functioning even after treatment and/or standard refractive correction, and has a visual acuity of less than 6/18 to light perception, or the visual field of less than 10° from the point of fixation, but use, or is potencially able to use vision for planning and/or execution of a task.” The WHO estimates that there are nearly 140 million people with low vision and 45 million who are blind. Furthermore, 80% of these cases could be avoided through prevention or treatment.

Visual impairment in childhood has impact on motor , cognitive and affective development. Etiological factors, age of incidence, presence of other disabilities, environmental factors and their interactions determine the difficulties and developmental delays of the child.

Congenital glaucoma occurs in 1 out of 10.000 live births. Glaucoma is a general term used to indicate damage to the optic nerve caused, or related to, elevated pressure in the eye. Glaucoma that begins within the first 3 years of life is called congenital. More than 50 percent of the congenital glaucoma is primary (anomaly of the drainage apparatus of the eye). Ocular or systemic development anomalies can also be associated with glaucoma and secondary glaucoma is related to other ocular abnormalities.

The profound visual loss is due to damage of optic nerve, corneal opacities, clouding and irregularities and refractive errors. The visual prognosis for children with congenital glaucoma is correlated to their age of presentation, early therapy interventions and treatment of associated amblyopia.

In spite of the succesful control of intraocular pressure after early surgical treatment, low vision is expected in many of the children. Low vision in childhood is responsible for their delayed development. Children must be refered to low vision services to promote the efficient use of vision and global development. School-age children with low vision due to congenital glaucoma can use low vision aids according to the profile of their visual functions and needs. These aids are optical, non optical and electronic devices. The goal is to achieve image magnification on the retina and modified environmental conditions to get better visual resolution of the fixated object.

The authors carried out a study of 99 children with visual impairment due to congenital glaucoma evaluated at University of São Paulo Low Vision Service, University of São Paulo Congenital Glaucoma Service and Laramara (Brazilian Association for Assistance for People Visual with Impairment). Data concerning visual acuity, refractive conditions and prescribed low vision optical aids was studied on 33 children that presented the following characteristics: age between 5 and 16 years, bilateral congenital glaucoma controlled by surgical / clinical treatment and no other associated disability.

Patients undergo an evaluation process that includes:

Ophthalmologic assessment: including complete examination of ocular conditions; visual acuity assessment, contrast sensitivity assessment; pupil reflex test; ocular movement test; refraction test, ophthalmoscopy and, when necessary, assessment of the visual field.
Functional vision and developmental assessment in order to better identify the difficulties and developmental delays of the child. It is carried out by teachers and physiotherapists specialized in the area of visual impairment.
A comprehensive psycological evaluation in order to understand the parents - child interaction.

Following the evaluation process, families and classroom teachers are given information about the children's disability and orientations at promoting the global development and efficient use of their vision. These activities are directed by teachers, physical therapists, orientation and mobility teachers and psychologists.

School-age children with low vision, aided by effective use of their residual vision are tested with special optical aids for their activities.

Data are presented in the following tables and figure. Prospective study concerning this population has been realized.

Table 3 - Distribution of monocular telescopic systems goes far distance

magnification	N	%
2 X	2	11
2,5X	1	5,5
2,8X	8	44,4
4 X	3	16,6
6 X	1	5,5
8 X	3	16,6
Total	18	100