Zonular cataract is one of the predominant congenital cataract. In this presentation we see its definition, pathology, risk factors, causes, signs and symptoms, diagnosis, treatment, prognosis. A cataract is an opacification of the lens. Congenital cataracts are also the most frequent cause of leukocoria (white pupil) in children

1. ZONULAR CATARACT
BY
DIVYA BHARGAVI

2. CATARACT
• A cataract is an opacification of the lens
• A congenital opacity of the crystalline lens. Cloudiness in the lens of the eye that is present at,
or develops shortly after birth.
• Congenital cataracts are also the most frequent cause of leukocoria (white pupil) in children
• Congenital cataracts usually are diagnosed at birth.
• If a cataract goes undetected in an infant, permanent visual loss may ensue.
• Not all cataracts are visually significant. If a lenticular opacity is in the visual axis, it is
considered visually significant and may lead to blindness.
• If the cataract is small, in the anterior portion of the lens, or in the periphery, no visual loss may
be present.

3. ZONULAR (LAMELLAR) CATARACT
• Zonular Cataract also known as Non-syndromic zonular cataract, Lamellar cataract
• Zonular Cataract is a rare inherited disorder, and is characterized by zonal opacification of
lenses
• The disease is progressive. However, the degree of progression may vary considerably among
affected individuals, as well as differences between the extent of lens opacity in the two eyes of
an affected individual
• The disorder may be caused by mutation(s) in the HSF4 gene, and is inherited in an autosomal
dominant manner
• If Zonular Cataract leads to vision impairment, surgical treatment is often necessary

4. TYPES
1. Nuclear cataract 3. Sutural cataract
2. Lamellar cataract 4. Subcapsular cataract

5. PATHOLOGY
• The commonest developmental cataract presenting with visual impairment.
• Accounts for 50% of visually significant cataract
• May be congenital/ occur 1st year of life or occurs at a later stage as development interfered at
a later stage
• Usually bilateral & hereditary(autosomal dominant), without any ocular anomaly.
• Zone around embryonic nucleus (usually in area of fetal nucleus) become opacified, extent
depending on duration of inhibiting factor
• Opacity sharply demarcated . Area of lens within & around opaque zone is clear

7. PATHOLOGY
• Zone around embryonic nucleus (usually in area of fetal nucleus) become opacified, extent depending on
duration of inhibiting factor . Opacity sharply demarcated . Area of lens within & around opaque zone is clear
• Consist of concentric, sharply demarcated zones(lamellae)
of opacities surrounding a core, that is clear, & enveloped by the
clear cortex externally.
• May be linear opacities, like spokes of a wheel (Called riders) that
extends outwards towards the equator
• pathognomonic.
• Fill pupillary aperture when pupil undiluted, thus affecting vision

8. RISK FACTORS (PREDISPOSING FACTORS)
• Zonular Cataract is a rare congenital disorder. The presentation of
symptoms may occur at birth
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected
• A positive family history may be an important risk factor, since Zonular
Cataract can be inherited

9. CAUSES
 Causes:
• Can be genetic and environmental in origin:
 Genetic:
• Zonular Cataract is caused by mutation(s) in the HSF4 gene. This gene codes for the heat shock
transcription factor 4
• These mutation(s) are inherited in an autosomal dominant manner
 Environmental:
• Ass. with hypovitaminosis vit D or hypocalcemia & maternal malnutrition
• Sometimes maternal rubella infection contracted between 7th and 8th week of gestation may also
cause lamellar cataract
• Malnutrition during pregnancy has been a/w non familial zonular cataract

10. SIGNS AND SYMPTOMS
 Signs and symptoms :
• The signs and symptoms of Zonular Cataract may vary amongst affected individuals in age of
onset, type and severity. Additionally, there may even be differences between the two eyes of
an affected individual.
• The signs and symptoms of Zonular Cataract may include:
• Partial or complete opacity of eye lens, leading to problems with vision
• Lazy eye (amblyopia)
• Photophobia may be a presenting symptom, mainly in lamellar or zonular type (due to light
scattering)

11. DIAGNOSIS
 Zonular Cataract is diagnosed on the basis of the following information:
• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Vision tests
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

12. DIAGNOSIS
 History:
1. Duration
2. Family history of congenital cataracts
3. Visual status: Ambulation in familiar & unfamiliar surroundings.
4. Behavioural pattern & school performance.
 Birth history:
1. History & Degree of consanguinity
2. History of maternal infection during 1st trimester
3. Gestational age & birth weight•
4. Birth trauma
5. Supplemental O2 therapy in perinatal period.
6. Developmental milestone

13. DIAGNOSIS
 Ocular examination:
1. Measurement of visual acuity• (An up to date refraction should be available as part of the
optometrist’s report)
2. Pupil examination
3. External eye examination including lids and lashes.
4. Measurement of intraocular pressure
5. Slit lamp examination• -associated congenital anomalies of iris & lens.
6. Dilated examination of the cataract and fundus
7. Biometry if the child is old enough to cooperate. If not this may need to be done under
anesthesia

14. COMPLICATIONS
• The complications of Zonular Cataract may include:
• Impaired vision
• Complete vision loss, if left untreated
• Complications may occur with or without treatment, and in some cases, due to treatment also

15. TREATMENT
• Zonular Cataract may necessitate surgical intervention, if the opacity in eyes leads to serious
vision impairment
• Surgery when VA less than 6/18
• Cataract surgery is the treatment of choice and should be performed when patients are
younger than 17 weeks to ensure minimal or no visual deprivation.
• Most ophthalmologists opt for surgery much earlier, ideally when patients are younger than 2
months, to prevent irreversible amblyopia and sensory nystagmus in the case of bilateral
congenital cataract
• Surgeries can include: Lensectomy, Extra-capsular Cataract Extraction (ECCE), Intra Ocular
Lenses (IOLs)

16. PREVENTION
• Zonular Cataract may not be preventable, since it is a genetic disorder
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis
(molecular testing of the fetus during pregnancy) may help in understanding the risks better
during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before
planning for a child
• Active research is currently being performed to explore the possibilities for treatment and
prevention of inherited and acquired genetic disorders
• Regular medical screening at periodic intervals with tests and physical examinations are
recommended

17. PROGNOSIS
• The prognosis of Zonular Cataract is dependent upon the severity of the signs and symptoms and
associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and
complications
• Typically, the prognosis may be assessed on a case-by-case basis
• The visual outcome depends on:-Unilateral /bilateral involvement-Density of cataract during
presentation-Degree of visual impairment
• Of persons with unilateral congenital cataracts, 40% develop visual acuity of 20/60 or better.
• Of persons with bilateral congenital cataracts, 70% develop visual acuity of 20/60 or better.
• The prognosis is poorer in persons with other ocular or systemic involvement.