congenital glaucoma and congenital cataract
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CONGENITAL GLAUCOMA&CONGENITAL CATARACT
DR REGINA LALRAMHLUNI II YR RSO
UPGRADED DEPARTMENT OF OPHTHALMOLGYMYH & MGMMC, INDORE
Occurs due to developmental defect in the trabecular meshwork & anterior chamber angle.
Noted by hippocrates
Recognsied by Von Muralt in 1869
Epidemiology 1 in 10,000 births
M:F = 3:2
25% diagnosed as newborn, 60% by 6 months, 80% by 1 year
Genetics Most are sporadic
Maybe autosomal dominant, autosomal recessive or multifactorial inheritance
three major loci (GLC3A, GLC3B, GLC3C) identified on chromosome 2, 1, 14 respectively
TERMINOLOGYRelating to age of onset:
1. Pediatric glaucoma: is a broad term referring to any form of glaucoma that may occur from birth to 18 years of age.
2. Congenital glaucoma: the glaucoma exists at birth and usually before birth..
3. Infantile glaucoma: occurs from birth until 3 years of life
4. Juvenile glaucoma: occurs after the age of 3 to teenage years
5. developmental glaucoma: if there is associated anomalies, either ocular or systemic
Relating to structural maldevelopment
1. Goniodysgenesis: maldevelopment of irido-corneal angle.
2. Trabeculodysgenesis: maldevelopment of trabecular meshwork.
3. Iridodysgenesis: maldevelopment of iris
4. Corneodysgenesis: maldevelopment of cornea
Figure1: The normal chamber angle: on the left is a histological cross-section; on the right is a drawing of the same
Figure 2: An underdeveloped chamber angle
PATHOGENESIS- Despite general agreement that abnormal development of the anterior chamber angle obstructs aqueous outflow (isolated trabeculodysgenesis), the exact nature of this abnormality has yet to be understood .
- Barkan initially postulated an impervious membrane over the trabecular meshwork k/as barkans membrane but it was disproved histopathologically.
Maumenee demonstrated developmental arrest of the iris and ciliary muscle(longitudinal and circular fibers) in the seventh month of gestation causes the insertion of the iris and ciliary body in an anterior location,over-lapping the trabecular meshwork.
Anderson provided histopathological support for the high insertion of the iris into TM
The trabecular meshwork has also been noted to have thickened trabecular beams and uveal cords,with narrowed trabecular spaces lead to impaired trabecular outflow.
Causes of visual loss- Corneal scarring / irregular astigmatism- Cataracts- Optic nerve damage- Anisometropic amblyopia - Strabismic amblyopia - Retinal pigmentary changes,detachment (possible complication after filtration ,seton,or cycloablative surgery)
A clinical triad of photophobia , epiphora , and blepharospasm is commonly associated with the presentation of primary congenital glaucoma
Others- cloudy cornea, enlarged cornea or eye, irritability, red eye, poor vison, pain.
-Tear in the descemets membrane (Habbs striae result from new basement membrane laid down by the endo. cells) ,which are single or multiple, oriented horizontally or concentric to the limbus associated with corneal edema in the early phases& have a significantly lower endothelial count. - In severe cases Acute hydrops may occur.
-Corneal enlargement is a very specific sign of PCG (Till 1st 3 yrs)
sclera also expands slowly(till ten yrs) under the influence of increased intraocular pressure and thinning brings about increased visibility of the underlying uveal tissue in neonates and causes the blue sclera
- In advanced cases ,the zonules may become stretched and rarely the lens may subluxate .
- Enlargement of the eye occurs under the influence of elevated intraocular pressure with major enlargement occurring at the corneo-scleral junction .
- As the axial length of the globe increases ,myopia and astigmatism occur.
- Cupping of the optic nerve proceeds more rapid and more likely to be reversible if IOP is normalized . The younger the child, the faster this reversibility
- symmetrical cupping has been attributed to stretching of the optic canal and backward bowing of lamina cribrosa .
- In eyes of young glaucoma patients there is often generalized enlargement of the optic cup with preservation of an intact neuroretinal rim.
- Hyphema,RD and Pthisis bulbi are often the final outcome of untreated or refractory glaucoma.
Management of Congenital Glaucoma
Office examination Following can be performed in children more than 5 year of age-Slit lamp examinationApplanation tonometeryGonioscopy Optic nerve evaluationRetinoscopyKinetic Goldman visual field testing(with the assistance of patient and encouraging perimeterist)
Examination under anaesthesiaGeneral anaesthesia is usually required for thorough examination of children under the age of 5 years.
Its sequential components consist of : -IOP measurement -Cornea assessment -Gonioscopy -Ophthalmoscopy -Additionally axial length measurement, UBM or cycloplegic Retinoscopy
IOP and tonometeryMost reliable IOP are obtained under intramuscular ketamine.
Perkins tonometer and Tonopen are reliably used to measure IOP in children
Infant and young children appear to have IOP lower than those expected in adults
Mean IOP of 9.59 mm of Hg is found in the newborn which rises to 13.95 by 7 or 8 year of age
Infant with primary congenital glaucoma may present with IOP exceeding 30 40 mm of Hg if unanesthetised, but may be much lower under the influence of inhalational anesthesia
Corneal diameter measurementAn effective measurement of the corneal diameter can be obtained using calipers to measure the horizontal diameter from the first appearance of the white scleral fiber at the limbus on one side to the same point on the other side, from the 9 oclock to 3 oclock position
Measuring the horizontal corneal diameter is a fundamental part of childhood glaucoma assessment
A horizontal corneal diameter of 12 mm in the first year of life associated with corneal oedema is pathognomic of glaucoma
GonioscopyIdeally a smooth domed Koeppe 14-16 mm lens with a Barkan light and hand- held binocular microscope is utilized for the purpose
A Goldmann goniolens is also used for viewing the angle through the operating microscope
If marked corneal clouding exists the view may be improved by using topical anhydrous glycerin or70% alcohol or 10% cocaine on a cotton tipped applicator
If necessary, edematous epithelium may also be removed using a surgical blade
Gonioscopic anatomy of normal infant eye- Iris inserts posterior to the scleral spur
- Flat iris insertion due to poor development of the angle recess till 6 to 12 months
- Ciliary body band is distinct in most cases
- TM appears thicker and more translucent than in adults
Gonioscopy of the eyes in infant with primary congenital glaucoma reveals
- Anterior insertion of the iris directly into the trabecular meshwork
- Stippled trabecular meshwork surface
- trabecular meshwork appear thicker than normal
- Peripheral iris shows thinning of the anterior stroma
- Angle is usually devoid of vessels although root of vessels from the major arterial circle is seen above the iris surface and has been referred to as Loch Ness Monster phenomenon
- The peripheral iris inserting into the trabecular meshwork may appear translucent and is referred to as the Listers morning mist
OphthalmoscopyOptic nerve cupping occurs rapidly in infant with elevated intraocular pressure and unlike in adult eyes, is also rapidly reversible with normalization of intraocular pressure
Persistent IOP elevation, however, causes glaucomatous optic atrophy due to loss of ganglion cells
C/D ratio greater than 0.3 are rare in healthy infant and should cause suspicion of glaucoma
Structural defect Isolated trabeculodysgenesis are highly responsive to both goniotomy and trabeculotomy ab externo
In iridotrabeculodysgenesis success rate for goniotomy and trabeculotomy decreases, multiple surgeries needed. Trabeculotomy is initial better procedure of choice
In iridocorneotrabeculodysgenesis prognosis for surgical treatment is poor. Ab externo combined trabeculotomy and trabeculectomy may be useful as initial procedure
Medical therapyB - blockerTimolol : is the most widely used beta blocker in children
It has been reported that plasma timolol level; after treatment with 0.25%timolol in children far exceeds adult plasma level, treated with 0.5%timolol
Reduction in heart rate, exacerbation of asthma and apnea has been reported in 4-13%of children treated
Avoided in neonates and the premature due to risk of sleep apnea
When indicated, timolol gel forming solution preferred due to lesser systemic absorption
Carbonic anhydrase inhibitors
- Temporary measure to reduce IOP and corneal edema prior to surgery- Doses 5-10 mg/kg/day in divided dose- Serious side effects include growth suppression, metabolic acidosis, drug idiosyncrasy, bone marrow suppression. Thus prolonged therapy is avoided- Currently topical dorzolamide is preferred and administered 2-3 times daily- Combination therapy of timolol and dorzolamide may be used in