Zonular cataract

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 ca taract 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 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

6. 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 p athognomonic. Fill pupillary aperture when pupil undiluted, thus affecting vision

7. 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

8. 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 7 th and 8 th week of gestation may also cause lamellar cataract Malnutrition during pregnancy has been a/w non familial zonular cataract

9. 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)

10. 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

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

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

13. 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

14. 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)

15. 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

16. 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.

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