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![EPIDEMIOLOGY IN SOUTH INDIA
Chennai is one of the four metropolitan cities in India and is popularly known as
the “health city” of India. In such an urban population, we found the prevalence
of blindness to be 0.85% (95% CI 0.6–1.1%), low vision 2.9% (95% CI 2.4–
3.4%), and visual impairment (blindness + low vision) 3.8% (95% CI 3.2–
4.4%)[1]
1.Prevalence and causes of low vision and blindness in an urban population: The Chennai Glaucoma Study](https://image.slidesharecdn.com/introduction-210201142246/85/Introduction-to-Low-Vision-10-320.jpg)
![ VITREOUS – Chromatic aberration decreases with age / Index of refraction of
the vitreous increases / Liquefaction and syneresis occur
RETINA - Visual acuity decreases as age increases / 75–85 years vision is less
than 6/7.5 [LogMAR 0.1] and they are entirely free from ocular disease Visual
field size decreases / Loss of ability to discriminate hues, especially at the
violet end of the spectrum / Mesopia and scotopia occur at lower levels of
ambient illumination / Absolute level of dark adaptation achieved is lower/
Delayed recovery to glare Loss of contract sensitivity at low frequencies /
Decrease in retinal illuminance / Decline in acuity with target velocity with
increasing age / Variability in visual performance increases with age](https://image.slidesharecdn.com/introduction-210201142246/85/Introduction-to-Low-Vision-29-320.jpg)
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Introduction to Low Vision
- 1. INTRODUCTION TO LOW VISIONAIDS MS.PRIYADHARSHINI.M LECTURER DEPT OF OPTOMETRY SCHOOL OF ALLIED HEALTH SCIENCES VINAYAKA MISSION’S RESEARCH FOUNDATION-DU
- 2. WHAT IS LOWVISION? A person whose visual acuity is <6/18 to Perception of Light in the better eye even after proper spectacle correction or Refraction is defined as Low vision Patients Or When a person’s Visual field loss is < 10◦ is termed as Low vision. When these defects affects a person’s regular tasks he/she can plan to use special device or equipment to do the tasks. WHO: ICD-10
- 3. THE TERM BLIND The term blind differs as Educationally , Legally or Functionally and is often used to indicate profound visual impairment. There are several blind associations for Blind
- 4. TERMINOLOGIES DISORDER Usually usedto describe the impact of the disease or injury on the anatomical structure of visual function within the organ or, in the case of vision, a component of the visual pathway IMPAIRMENT The consequence, in terms of measurable loss or departure from functional capacity, to the bodily organ, affected by disorder or disease, of an anatomical or physiological function DISABILITY The consequence to the patient in terms of the effect of the impairment on the patient’s abilities HANDICAP The consequence of the disability in terms of how it affects the patient’s ability to interact with society
- 5. DEGREES OF VISUALIMPAIRMENT VISUAL IMPAIRMENT PARTIALLY BLIND LOW VISION SUBNORMAL VISION (between 6/24 and 6/60) (<6/18 to PL) (6/18 TO PL)
- 6. QUANTIFYING CATEGORY OFBLINDNESS GROUP 1 DESCRIPTION 1 Visual acuity of less than 3/60 or less than 1/18 if tested at a closer distance, in a patient with full visual fields 2 Visual acuities ranging from 3/60 to less than 6/60 with significantly contracted visual fields 3 Visual acuity of 6/60 or better with a gross visual field constriction, particularly in the lower field
- 7. QUANTIFYING CATEGORY OFPARTIALLY SIGHT GROUP 1 DESCRIPTION 1 Visual acuity of 3/60 to 6/60 with full fields 2 Visual acuity of up to 6/24 with a moderate field constriction, medial opacities or aphakia 3 Visual acuity of 6/18 or better with a gross field defect (i.e. hemianopia)
- 8.
- 9. LOW VISION Thoseapproaching the problem of visual impairment from an optical or optometric background advocate the term ‘low vision’, which to a large extent has evolved from the term ‘subnormal vision’. This term is almost synonymous with visual impairment, with the added provision that the residual vision is usable.
- 10. EPIDEMIOLOGY IN SOUTHINDIA Chennai is one of the four metropolitan cities in India and is popularly known as the “health city” of India. In such an urban population, we found the prevalence of blindness to be 0.85% (95% CI 0.6–1.1%), low vision 2.9% (95% CI 2.4– 3.4%), and visual impairment (blindness + low vision) 3.8% (95% CI 3.2– 4.4%)[1] 1.Prevalence and causes of low vision and blindness in an urban population: The Chennai Glaucoma Study
- 11. VISUAL IMPAIRMENT INCHILDREN Visual loss in childhood and the early teens is predominantly congenital or hereditary in nature. The three most common clinical scenarios presenting to the ophthalmologist are •The neonate or young baby who appears to be visually impaired • The visually impaired baby with no obvious ophthalmic abnormality • The child with visual difficulty.
- 12. CONTD…. Eighty-three percent of neonates will follow a face but not a white light. A smile in response to a silent smile should be present at 6 weeks of age and indicates good central vision. Abnormal eye movements and visual inattention are the most common signs of poor vision. The more uncoordinated the movements, the more impaired the visual acuity.
- 13.
- 14. The neonate oryoung baby who appears to be visually impaired • Albinism • Cerebral blindness • Congenital cataract • Congenital glaucoma • Congenital idiopathic nystagmus • High refractive error • Leber’s congenital amaurosis • Macular colobomata • Optic atrophy or hypoplasia • Primary hyperplastic vitreous • Retinoblastoma • Retinopathy of prematurity.
- 15. History and examination Normally sighted in infancy. Normal early studies Starts with the poor vision while seeing blackboard In this age group a history of the visual symptoms and a positive family history of inherited conditions may also be present. Children with decreased distance acuity with good near acuity may simply be myopic. optic atrophy-complain of reducing vision but usually have no other specific symptoms cone dystrophies – intense photophobia and difficulty with colour vision.
- 16. early-onset retinitispigmentosa - night blindness or restriction of fields
- 17. Classification of Lossor Impairment – Disorder and Impairment Relate to the Organ whereas Disability and Handicap Relate to the Person DISORDER IMPAIRMENT DISABILITY HANDICAP Disease or injury Reduced functional Performance Reduced skills or abilities Limitations on social performance participation ARMD Reduced VA and CS Reading speed and fluency reduced Difficulty in accessing written contents RP Contracted VF, reduced CS and impaired night reduced Walking speed Mobility problems travel and resulting social vision CONGENITAL CATARACT Reduced VA & CS,glare, and reduced near visual acuity Reading more difficult Difficulty in mobility and isolate OCULOCUTANEOUS ALBINISM Reduced VA & CS,Photophobia Mobility difficult in bright light and DV problem Restrictions to certain travel tasks THE ORGAN THE PERSON
- 18. Visual Prognosis, VisualField Loss in Inherited Diseases CONDITION VISUAL PROGNOSIS VISUAL FIELD DEFECT VISUAL AIDS LEBER’S AMAUROSIS VERY POOR COMPLETE LOSS OF VF REQUIRES SOME SPECIAL TECHNIQUES OPTIC ATROPHY VARIABLE PARACENTRAL SCOTOMAS GOOD WITH LVA’S CEREBRAL BLINDNESS POOR DIFFICULT TO TEST NEED ENVIRONMENTAL MODIFICATION DELAYED VISUAL DEVELOPMENT NORMAL VISION OFTEN DEVELOPS NORMAL GOOD WITH LVA AND TRAINING WHEN GETS OLDER
- 19. Overview of theFunctional Classification of Disability and Health FUNCTION & STRUCTURE ACTIVITIES AND PARTICIPATION ENVIRONMENTAL PERSONAL DOMAINS Bodily functions Life areas (Tasks and actions) External influence Internal influences CONSTRUCTS Anatomical and Physiological changes Capacity and performance Hindrances of features in physical and social world Impact of attributes on person POSITIVE ASPECTS Functional and Structural integrity Activity participation Facilitators functioning NA NEGATIVE ASPECTS Impairment and Disability Activity limitation and participation restriction Barriers and Hindrances NA FUNCTIONING & DISABILTIES CONTEXTUAL FACTORS
- 20. Ophthalmic disorders presentingin childhood Best’s disease or vitelliform dystrophy Cone dystrophy Optic atrophy Retinitis pigmentosa Stargardt’s disease or fundus flavimaculatus X-linked retinoschisis
- 21. OPTIC ATROPHY: Thedeath of the retinal ganglion cell axons that comprise the optic nerve with the resulting picture of a pale optic nerve on fundoscopy. Vitelliform dystrophy or Best’s disease : Also known as vitelliform macular dystrophy, is an inherited retinal disease causing macular degeneration. Stargardt’s disease or fundus flavimaculatus : An inherited disease, meaning it is passed on to children from their parents. Stargardt disease is a form of macular degeneration, and is often called juvenile macular degeneration.
- 22. Cone dystrophy: An inherited ocular disorder characterized by the loss of cone cells, the photoreceptors responsible for both central and color vision. X-linked retinoschisis : A rare congenital disease of the retina caused by mutations in the RS1 gene, which encodes retinoschisin, a protein involved in intercellular adhesion and likely retinal cellular organization. X-linked retinoschisis has also been referred to as: juvenile retinoschisis, congenital retinoschisis, juvenile macular degeneration/dystrophy, and degenerative retinoschisis.
- 24. Retinitis pigmentosa: Agenetic disorder of the eyes that causes loss of vision. Symptoms include trouble seeing at night and decreased peripheral vision (side vision). As peripheral vision worsens, people may experience "tunnel vision". Complete blindness is uncommon. Usher’s syndrome : Usher syndrome is a rare genetic disorder primarily characterized by deafness due to an impaired ability of the inner ear and auditory nerves to transmit sensory (sound) input to the brain (sensorineual hearing loss) accompanied by retinitis pigmentosa, a disorder that affects the retina and causes progressive loss of vision.
- 25. Disorders presenting inadolescence Best’s disease or vitelliform dystrophy Cone dystrophy Leber’s optic neuropathy Retinitis pigmentosa Stargardt’s disease or fundus flavimaculatus.
- 26. Two rarebut important systemic diseases are abetalipoproteinaemia (Bassen– Kornzweig syndrome) and Refsum’s disease in young An inherited disorder that impairs the normal absorption of fats and certain vitamins from the diet. Many of the signs and symptoms of abetalipoproteinemia result from a severe shortage (deficiency) of fat- soluble vitamins (vitamins A, E, and K) An inherited condition that causes vision loss, absence of the sense of smell (anosmia), and a variety of other signs and symptoms. The vision loss associated with Refsum disease is caused by an eye disorder called retinitis pigmentosa.
- 27. USES OF LOWVISION AIDS Most children with mild to moderate visual impairment can cope in normal school, given the following provisions: • Good parental understanding of the problem • Teaching and advisory peripatetic support • A bright and dexterous child. Dome magnifiers are often the aid of choice for albinos and those with congenital nystagmus. Aphakic children require higher levels of magnification and benefit from stand magnification (×3 to ×12) or spectacle magnifiers (single vision or bifocal). Children with retinitis pigmentosa and central visual loss benefi t from closed circuit televisions (CCTVs) Distance low vision aids can be used by virtually all schoolaged visually impaired children
- 28. Non-pathological Changes inthe Eye with Age CORNEA - Corneal sensitivity to touch is decreased / Increase in ‘against the rule’ astigmatism AC - Anterior chamber depth decreases with age IRIS - Senile miosis / Pigment desquamation into the anterior chamber LENS - Increase in axial thickness by about 28% / Increase in the amount of yellow pigment leading to decreased sensitivity at the violet end of the spectrum / Decrease in accommodation, possibly due to a decrease in capsular elastic force / Little evidence to support atrophy or sclerosis of the ciliary muscle
- 29. VITREOUS –Chromatic aberration decreases with age / Index of refraction of the vitreous increases / Liquefaction and syneresis occur RETINA - Visual acuity decreases as age increases / 75–85 years vision is less than 6/7.5 [LogMAR 0.1] and they are entirely free from ocular disease Visual field size decreases / Loss of ability to discriminate hues, especially at the violet end of the spectrum / Mesopia and scotopia occur at lower levels of ambient illumination / Absolute level of dark adaptation achieved is lower/ Delayed recovery to glare Loss of contract sensitivity at low frequencies / Decrease in retinal illuminance / Decline in acuity with target velocity with increasing age / Variability in visual performance increases with age
- 30. REFERENCE A.Jonathan Jackson,JamesS Wolffsohn, Low vision Manual , ISBN-13: 978- 07506-1815-1 ISBN-10: 0-7506-1815-9
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