NIGHTBLINDNESS AND

XEROPHTHALMIA

Raju Kaiti

Consultant Optometrist

Dhulikhel Hospital, KU

Definition• Also termed as ‘nyctalopia’

• It is defined as diminution of vision in dim light

• It occurs due to defect in transition from photopic to scotopic vision

• Apart from adaptation of mainly photoreceptor rods and then cones, the neural adaptation mechanism also plays role in dark adaptation

Causes

• Retinitis pigmentosa (RP)• Vitamin A deficiency• Gyrate atrophy of choroid and retina• Congenital stationary night blindness (CSNB)• Choroidermia• Myopia

Other causes of Nyctalopia

• Glaucoma• Optic nerve atrophy • Cortical cataract• Panretinal photocoagulation• Zinc deficiency• Drugs – phenothiazine, chloroquine,

hydroxycholoquine

Myopia• Myopic patients also complain of night blindness

which may be the most common cause of poor night vision

• However it is should not confused with blurring of vision in dim light as seen in all refractive disorders

• In very high myopes degenerative changes in choroid and retina lead to subnormal ERG and delayed dark adaptation

RETINITIS PIGMENTOSA• Most frequently seen retinal dystrophy• The term "retinitis" pigmentosa -Donders(1855)• The term "pigmentary degeneration"-von

Graefe(1858)• "Pigmentary retinal dystrophy" -appropriate termPathology• Degeneration of retinal neuroepithelium• particularly of rods• Degeneration of entire retina, RPE, and also

choriocapillaris

CLINICAL PRESENTATION:• Symptomatic onset between

age of 5-30 yrs may occur in 4th or 5th

decades• Symptoms: Difficulty in seeing at

night Daily-life handicap • SignClinical triad- Retinal arteriolar

narrowing Bony spicules Optic disc pallor

Clinical features of RP• Incidence in 1:4000

• Night blindness is one of the hallmark symptoms in RP which usually begin in first or second decade of life

• Visual field loss is second hallmark of RP which is insidious and progressive

• Central vision loss• Light flashes• Loss of color vision• Hearing loss – associated in 30 % RP patients

Clinical FindingsOther Findings: • Lens- Opacity , PSCC type • Vitreous-Condensations, opacities,

cells, PVD • Macula- Early broadening or

loss of the F. R. Epiretinal membrane

changes Pigment epithelial alterations-

mottling, bull's eye, atrophy, pigmentation

• Macular oedema• Full thickness holes

Vitamin A deficiency• Primary cause of childhood blindness in Nepal

• Night blindness is a very sensitive although not very specific indicator of vitamin A deficiency

• Vitamin A forms rhodopsin also known as visual purple present in photoreceptor rods

• The sensitivity of rods is approximately proportional to antilogarithm of rhodopsin concentration

• Deficiency hence impairs functioning of photoreceptor rods leading to night blindness

CHOROIDEREMIA

• X-linked recessive disease

• Granularity and depigmentation of the RPE can be seen around the peripheral fundus.

• Full-field ERGs are reduced in amplitude and delayed in b-wave implicit time with minimally increased dark-adaptation thresholds, and full visual fields

CHOROIDEREMIA

CHOROIDEREMIAIn more advanced stages dark-adaptation thresholds are further increased and the visual fields become constricted;

Female carriers of this disease may demonstrate fundus changes that include patchy depigmentation of the RPE.

However, carriers typically retain normal visual acuities and normal final dark-adapted rod thresholds

GYRATE ATROPHY OF CHOROID AND RETINA

GYRATE ATROPHY OF CHOROID AND RETINA

inherited by an autosomal recessive mode of transmission

Patients usually present in early adolescence with night deficiency and loss of peripheral vision.

Ocular findings include myopia, constricted visual fields, elevated dark-adaptation thresholds, reduced ERG responses and chorioretinal atrophy distributed circumferentially around the peripheral fundus

Stationary forms of night blindness

• Life long stable abnormality of scotpic vision having early onset

Subtypes:• CSNB with normal fundus• CSNB with abnormal fundus

CSNB with normal fundus• X-linked• AD • AR

Stationary forms of night blindness

• CSNB with normal fundusX-linked –commonest• genetic defect- locus Xp11, mutation in rhodopsin

gene• Defect is lies in the failure of communication

between proximal ends of photorecetors and bipolar cells

• some pts. Do not c/o nyctalopia( way of life)• Nystagmus decrease VA or myopia• Range of VA- Normal to 6/60

CSNB• CSNB with abnormal

fundus Fundus Albipunctatus

(AR) Oguchi’s Disease (AR)

Mizuo’s phenomenon

Approach to NBTaking History ( complaints)

1. Night blindness (How do they present to us?) Progressive (RP) Stationary (CSNB) Sudden( paraneoplastic process) Age of onset – imp. Younger (x-linked RP, CSNB)

Contd…..

2. Visual loss : Gradual , progressive Age of onset3. Visual field constriction: peripheral or central How can they present to us?

Medical History• Operations ( Intestinal surgeries, removal of

polydactyl)• Liver diseases• Use of medicine- Hydroxycholoquine or

phenothiazine• Hearing status( RP, Usher’s Syndrome,choroideremia,

Refsum’s)• Mental retardation( BBS,LMS)• Renal disease (BBS)• Heart disease (KSS, Refsum’s)

Family History

• Any NB in past 3 consecutive generation (Dominant RP)

• Anyone in the family affected by retinal degeneration

• Consanguinity

General Examinationwt. loss- vit A deficiency truncal obesity –(Bardet-Biedl Syndrome)

Systemic evaluation:

CVS- Kearn-Sayre Syndrome( ECG- Heart block)

P/A- Colostomy, surgical scars

ENT- Hearing loss ( Usher’s, RP, Choroideremia)

NS – Mental retardation( Bardet-Biedl Syndrome, Gyrate Atrophy Choroidermia, LMS) ,Spastic paraplegia (LMS)

Urogenital- hypogenitalism( Bardet- Biedl syndrome)

Musculo-Skeletal –Polydactyl (Bardet- Biedl syndrome, LMS), muscle weakness(Gyrate Atrophy), deformity (Choroidermia)

Skin – Melanoma ( paraneoplastic cause)

Ocular EvaluationVisual AcuityEOM ( external ophthalmoplegia- KSS, Bassen-Kornzweig, Refsum’s)Lid ( ptosis- KSS)Lens – PSCC- ( RP, Choroideremia, Gyrate Atrophy)Vitreous – fibrillar changes ( Choroideremia), PVD( Gyrate Atrophy)Fundus-Normal or Abnormal Normal fundus ( CSNB)Refractive Status Myopia- ( RP,choroideremia, Gyrate Atrophy) High Myopia ( CSNB) Astigmatism-( RP)

Fundus Changes in cases of NB

•RP

Choroideremia

Gyrate atrophy

Fundus Changes

Oguchi

Investigations • Visual fields( All)

• Dark Adaptometry

• ERG( all)

• Color vision( later stages of RP)

• Biochemical: Ser. Vit A level Ser. Lipoprotein( Bassen – Kornzweig syndrome) Ser. Phytanic acid level ( Refsum’s) Ser. Ornithine level( Gyrate Atrophy)

ManagementStaging ( current VA, VF, dark adaptation, color vision, rod-cone ERG)

Give devices for maximizing remaining vision

Monitoring Disease progression- 2yrs.-VF,ERG,Va

Counseling – Genetic + Vocational

Medical T/T: Vit. A, Acetazolimide, Docosahexanoic acid(DHA)-trial( RP) Vit A, K, E( Bassen- Kornzweig) Vit B6 ( Gyrate Atrophy)

XEROPHTHALMIA

Definition:

• Xerophthalmia is the general term applied to all the ocular manifestations of impaired Vitamin A metabolism, from night blindness through complete corneal destruction

XEROPHTHALMIA• Xerophthalmia

• Xeros --- Dry

• Ophthalmia --- Eye

• literally means “dry eye,”

• Many causes of dry eye but conventionally Xerophthalmia has become synonymous with vitamin A deficiency.

RDA: 5000 IU for men         4000 IU for women

Sources: liver, egg yolks and dairy products, tomatoes, yellow and green leafy vegetables, and fish liver oils.

Vitamin A helps the eyes , the skin and the development of healthy teeth and bones.

we can also battle stress with enough of this vitamin.

Deficiency will also make susceptible to infection

Risk Factors

• Protein Energy Malnutrition

• Measles, Chickenpox, High Fevers

• Bronchopneumonia, Tuberculosis, Diphtheria

• Gastroenteritis, Dysentery, Worm Infestations

Xerophthalmia in Nepal:• Two sources of information

– Tribhuvan University Survey (1980-1981 AD)– Nepal Blindness Survey (1980-1981 AD)

• Major public health problem

• 0.9% bilateral blindness due to nutritional corneal ulceration

• Every day one child dies and one child goes blind of xerophthalmia

Normal Vitamin A MetabolismDietary Vitamin A(Carotenes in plant food)(Retinol in animal food)

Digestion and absorption of Vitamin A from the food Transport in intestinal lymphatics

1. Storage of Vitamin A in liver cells as retinol2. Production of retinol binding protein (the carrier protein)

Transport of retinol bound to retinol binding protein

1. Formation of rhodopsin - used in night vision2. Maintenance of healthy corneal and conjunctival cells

FOOD

INTESTINE

LIVER

BLOOD

EYE

Vitamin A Deficieny

Dietary deficiency of Vitamin A

Diarrhoea; Gastroenteritis; Parasites

Not enough Vitamin A stored in the liver

Low Vitamin A levels in the blood

Night Blindness

FOOD

INTESTINE

LIVER

BLOOD

EYE

Anorexia from other diseases

Protein Energy Malnutrition

Poor intestinal absorption

Not enough Retinol Binding Protein synthesis

Xerophthalmia

Slide XE01Conjunctival xerosis (X1A) and corneal xerosis (X2)The term conjunctival xerosis (X1A) applies to any stage of xerotic change in the conjunctiva, with thickening and wrinkling in advanced cases as in this slide. In this case there is also infiltration and haziness of the cornea (X2).

Bitot’s spot is a single or multiple heaping up of desquamated keratinised bulbar conjunctival epithelial cells, most commonly in the inter-palpebral fissure on the temporal aspect of the eye. Most spots are foamy, some are more solid and cheese-like. In children under the age of about 6 years they usually respond to vitamin A dosing. However, sometimes they are unresponsive and then probably indicative of VAD in the past. In older children and adults they are usually unrelated to VAD.

• Most of the bulbar conjunctiva is covered with foamy, keratinised epithelial cells. The cornea is hazy and the limbus is infiltrated by fine blood vessels (neovascularisation).

Most of the bulbar conjunctiva is covered with foamy, keratinised epithelial cells. The cornea is hazy and the limbus is infiltrated by fine blood vessels(neovascularisation).

Cloudy cornea, corneal ulcer

Keratomalacia is due to severe VAD in which the cornea liquefies in the acute stage. On resolution various types of corneal destruction/scarring are inevitable, as is visual impairment

• A case that could be treated. • An advanced state of deficiency

with keratomalacia.

The same eye one month after treatment. The child was treated immediately with large doses of vitamin A. The cornea has healed and there is only a scare left in the lower part, not impairing vision. This child was lucky.

Scars attributable to VAD are usually bilateral and located in the central and inferior portion of the cornea. In the field these inactive lesions are often one of the commonest clinical pieces of evidence of a public health problem of VAD in the past. However, a careful history must be taken to exclude those not related to VAD in the past; they might result from injury or infectious eye disease.

Plate 1: Xerophthalmic fundus in a 24-year-old otherwise well nourished Indonesian woman who presented with night blindness, constricted visual fields and severe conjunctival and corneal xerosis.Plate 2: Two months after vitamin A therapy the small yellowish-white retinal lesions in the patient in Plate 1 have largely disappeared

Eye Changes

1. ConjunctivaX1AX1B

+ XN2. Cornea

X2X3AX3BXS

3. RetinaXNXF

Warning Sign

Medical + Ophthalmological Emergency

First Sign of Xerophthalmia

The Recommended Doses of Vitamin A

• Prophylactic Schedule:Dose By Mouthmg I.U.

– All Children 110 200,000Every 4 -6 months

– Mothers 110 200,000Just after giving birth

For children less than 1 year of age, reduce dose by one half

The Recommended Doses of Vitamin A

• Treatment Schedule:

If the children is severely ill with gastroenteritis or unable to swallow, the first dose should be intramuscular injection water soluble Vitamin A

Emergency Treatment of Children with Xerophthalmia or Corneal Ulcers

Day / Week Dose By Mouthmg I.U.

Day 1 110 200,000Day 2 110 200,000Day 14(2-4 Weeks)

110 200,000

National Vitamin A Programme

• Children : 6 months - 5 years (3.5 Million)• Twice a year : April 18 & 19

October 18 & 19• Coverage :75 districts - 85%• FCHV : 48,000• Reduction of Child Mortality : 20-25 thousand

Prevention of Xerophthalmia

• Distribution of Massive Dose Capsules• Fortification of Foods• Horticulture and Agriculture• Nutrition and Health Education

i. Late Weaningii. Early Supplementationiii. Mass Media Radio, TViv. Changing Eating Habits

• Immunization

Treatment of XerophthalmiaA. MEDICAL

1. Vitamin A Massive Dosing• Oral: Day 1, 2, 14 - 200,000 I.U.• Injection: 1st Day Only - 100,000 I.U.

Water MiscibleNo oily preparation

If not available: Give food rich in Vitamin A

2. Supportive Therapy• Fluids• Proteins• Control of Infection• Deworming

Treatment of XerophthalmiaA. MEDICAL

3. Eye• Antibiotcs, Mydiatrics• Pad specially in X3A, X3B• Avoid Exposure: Antibiotic Ointment• Methyl Cellulose Drops

B. SURGERY1. Conjunctivoplasty2. Keratoplasty

a. Prophylacticb. Optical

C. REHABILITATION

Prevention of Vitamin A deficiency

– Breastfeeding – Vitamin A

supplementation – Food fortification – Promotion of

vitamin A-rich diets

THANK

YOU…………………