Cataract formation is a common sequel toblunt trauma.Also associated with Subluxation ,dislocationIt is the most common cause of Unilateralcataract in young individuals.
1 Penetrating trauma2 Blunt trauma may cause a characteristic flower-shapedopacity3 Electric shock and lightning strike are very rare causesthat may result in anterior and posterior iridescentopacities that have a stellate pattern4 Infrared radiation, if intense as in glassblowers, mayrarely cause true exfoliation of the anterior lens capsule5 Ionizing radiation for ocular tumours may causeposterior subcapsular opacities that may develop monthsor years later.
Postulated mechanismsTraumatic damage to the lens fibresRuptures in the lens capsuleinflux of aqueous humourHydration of lens fibresOPACIFICATION
A ring-shaped anterior subcapsular opacity may underlie a Vossiusring [. Imprinting of iris pigment on anterior lens capsule] Commonly opacification occurs in the posterior subcapsularcortex along the posterior sutures, resulting in flower -shaped opacity[rossette] which may subsequently disappear, remain stationary orprogress to maturity. Cataract surgery may be necessary for visually significant opacity. Lens protein leak can lead to secondary Glaucoma,uveitis.
Subluxation of the lens may occur, secondary to tearing of the suspensory ligament. A subluxated lens tends to deviate towards the meridian of intactzonule the anterior chamber may deepen over the area of zonulardehiscence, if the lens rotates posteriorly. The edge of a subluxated lens may be visible under mydriasis Trembling of the iris (iridodonesis) or lens (phakodonesis)on ocular movement.Subluxation to render the pupil partly aphakic may result inUniocular diplopia ; lenticular astigmatism due to tilting mayoccur.
Dislocation due to 360° rupture of thezonular fibres is rare and may be into thevitreous, or less commonly, into the anteriorchamber an underlying predisposingcondition should be suspected.
A slowly progressive or stationary cataractespecially dense cataracts with a history ofocular trauma should be removed if only visuallysignificant for the patient. Gross visual field defects,Afferent pupillarydefect, Sphincter tears,iridodialysis,elevated orabnormal low IOP,angle anomalies ,ultrasoundevidence of posterior segment pathology shouldbe looked for by the surgeon.
Visualization:In case of corneal laceration /edema whichimpairs ability to remove lens material –Open –sky approach .In case of Haemorrhage interfering with view– OVDs /air is helpful
Inflammation:In case of synechiae,pupil seclusion,distorsion- Gentle sweeping to dilate, pupilloplasty,Peripheral iridectomy – to prevent pupillaryblock.- Cycloplegics , topical & oral steroid therapy.
Primary IOL insertion when intraocularinflammation and haemorrhage are minimaland view of anterior segment structures isgood.
Retained foreign matter:Indirect ophthalmoscopy if view is clear.Ct scan/Ultrasound if inadequate viewMRI if not metallic body.Pars plana /anterior approach along with lensimplantation then PPV.Irrigating solutions to dislodge foreign bodyintracamerally.
Damage to other ocular tissues:In sphincter rupture ,distortion andiridodialysis – Repair by suturing iris root toscleral spur.
Zonular dehiscence and dislocation:- OVD tamponade of vitreous , Capsulartension ring in capsular bag , removal ofcataract through Pars plana- ACIOL .Transcleral fixated PCIOL
A secondary (complicated) cataract develops as a result of someother primary ocular disease. Chronic anterior uveitis- It is the most common cause.- Related to the duration and activity of intraocularinflammation that results in prolonged breakdown of theblood–aqueous and/or blood–vitreous barrier.The use of steroids, topically and systemically, is important.The earliest finding is a polychromatic lustre at the posterior poleof the lens which may not progress if the uveitis is arrested. If theinflammation persists, posterior and anterior opacities developthat may progress to maturity.The opacities appear to progressmore rapidly in the presence of posterior synechiae.
Acute congestive angle-closure may cause small, grey-white,anterior, subcapsular or capsular opacities within the pupillary area(glaukomflecken )– focal infarcts of the lens epitheliumpathognomonic of past acute angle-closure glaucoma. High (pathological) myopia is associated with posteriorsubcapsular lens opacities and early-onset nuclear sclerosis, whichmay ironically increase the myopic refractive error. Simplemyopia, however, is not associated with such cataract formation. Hereditary fundus dystrophies, such as retinitis pigmentosa, Lebercongenital amaurosis, gyrate atrophy and Stickler syndrome, maybe associated with posterior subcapsular lens opacities Cataractsurgery may occasionally improve visual acuity even in thepresence of severe retinal changes.