Post on 23-Jan-2018
LOW VISION:COMPREHENSIVE
BY VIVEK
CHAUDHARY8TH DEC 2016
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Low vision can be described as reduced vision which cannot be corrected by optical or surgical means
WHO, “ A person with low vision is one who has impairment and/or standard refractive correction and has a visual acuity of less than 6/18 to light perception in the better eye or a visual field of less than 10 degrees from the point of fixation, but who uses or is potentially able to use, vision for planning and/or execution of a task”
Conditions causing low vision
It includes :
ARMD ( Age Related Macular Degeneration) – Central loss
Diabetes- Retinopathy Laser treatment
Acquired (traumatic) brain injury
Nystagmus
Congenital cataract
Multiple sclerosis
Glaucoma
Albinism
Retinitis pigmentosa
1.ARMD
Idiopathic. Age is the primary factor for ARMD
Also caused by cigarette and nutritional imbalance.
Most common cause of visual loss in Western countries
Causes central vision loss
Non-exudative ARMD causes slow progress of vision loss
Exudative ARMD causes rapid progress of vision loss
Visual Acuity may vary with the extent of the degeneration :• With dry stages ARMD, acuity can range from 6/6 to 6/120.• With wet stage(exudative) ARMD, the acuity can show worse than
6/120• Main problem is very difficulty to reading or writing.
Central vision loss
Amsler Grid
2. Diabetic Retinopathy
leading cause of blindness in the U.S for patients age 20 to 74.
Vision loss due to two major problems : a. Macular edema b. proliferative DR
Effects on vision ;
• Fluctuating vision
• Loss f central sharp vision
• Profound loss of vision
• Color vision impairment
• Reduced side vision after LASER
• Night Blindness after LASER
• Glaucoma
• Cataracts
Traumatic Brain Injury (TBI)
Loss of Visual Field : homonymous hemianopia mostly
Visual spatial disorders and visual neglect
Vertigo, dizziness and impaired eye movements
Double vision
Eye strain and difficulty in reading
Light sensitivity , Dry eyes
Visual hallucinations
Impaired visual memory
Nystagmus
Def : Involuntary, rhythmic shaking of the eyes (dancing eyes or jerking eyes).
Effects on vision
Fluctuating vision
Null position : unusual head and eye position
Binocular vision impairment
Congenital Cataracts
Cataract formation since birth
Occurs due to birth defects like Down syndrome, congenital rubella, inherent cataract and so on
OR due to drug infection like Tetracycline which is given for pregnant women for infection
Very rare to occur
Multiple Sclerosis
Def : demyelinating disease in which the insulating cover of nerve cells in the brain and spinal cord are damaged.
Visual symptoms include Optic neuritis, Nystagmus and Diplopia
Glaucoma
2nd leading cause of blindness
Portions of VF lost usually with no warning signs or symptoms prior to Vn deterioration
Decreased peripheral vision is the first sign.
Damages the optic nerve at the back of the eye leading to blindness
Visual effects include gradual blurred Vn, photophobia, seeing halos around light and vision loss in end stage
Problem with orientation and mobility
Albinism
Def : defect in melanin pigment production
Effects on eyes , skin and hair
Is inherited in an X-lined fashion
No RPE makes blood vessels visible of the choroid
Visual symptoms include light blue eyes, photosensitivity, nystagmus and strabismus
VA ranges from 20/40 to 20/200
LOW VISION AIDS
WHY AND NEEDS OF LVA
Needs
Those with worsening sight and the prognosis of eventual blondness are at comparatively high risk of suicide.
These people can be given low vision aids
LVA enhances the residual vision
Makes individual do regular life activities.
Via devices which are Optical , Non optical , electro-optical devices
Aim is to magnify the image to be visible to patient
Optical devices for distance
Telescopes Handheld or spectacle mounted
Keplerian Telescope
Galiliean telescope
Optical devices for near
Spectacle : bifocals
Magnifiers : handheld , stand and illuminated or non illuminated
Electronic devices :CCTV
Others : clip on loupes
Bioptic
Microscpoic lenses
High addition lenses
Non optical devices
Typoscopes
Writing guide (signature, text, cheque)
Illuminations
Clour or tint
Glare control devices
Contrast enhancing
Low vision assessment
History
Visual acuity and refraction
others
History
Ocular history : to know the cause of the LV and progress of the disease
Systemic disease that may pose difficulty in using certain devices : arthritis or tremors
Refraction and visual acuity
Distance visual acuity : light house distance visual acuity test chart
Near visual acuity : light house near visual acuity test chart
Benefits of lighthouse test chart over Snellen
GP of each optotype size from line to line
Five letters on each line
Test distance of 2 m can be used to cover VA of 20/400
Others
Contrast sensitivity
Visual filed analysis ;
Peripheral field using Humphrey or octopus perimetry
Central field using amsler grid
glare : history and measuring VA with or without illumination in the chart
Colour vision
Low vision & low vision rehabilitation
A person with a significant reduction in visual acuity due to ocular diseases that is not correctable by surgery, conventional eye glasses or contact lenses has Low Vision.
The process of helping a person with low vision achieve the highest level of visual function, independence, and quality of life possible is Low Vision Rehabilitation
Objectives
To develop independent living skills of visually impaired people and help them regain self confidence for reintegrating into the community
Identification
Assessment of LV
Assessment of handicap
Management of LV to make it useful vision
Device and training
Social and environmental adaptation
Smart management : Things to do
Listen , listen and listen
Detail explanation about LV rehab programme
Psychological management
Friendly advice and counselling
Follow up
THANK YOU !