LOW VISION:COMPREHENSIVE

BY VIVEK

CHAUDHARY8TH DEC 2016

.

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 !