Seven rings of trauma
Seven rings of trauma are circumferentially oriented ocular tissues which are classically disrupted following a closed globe injury.
- Sphincter pupillae - The sphincter pupillae is the involuntary muscle responsible for pupillary constriction mediated by parasympathetic nervous system. This muscle encircles the pupillary margin of the iris and is 0.75mm wide. Sphincter tear is seen as distuption of pupillary margin in slit lamp biomicroscopy and may be associated with traumatic mydriasis.
- The iris base - iridodialysis. Iridodialysis is clinically seen as dehiscence of iris from the sclera and a D shaped pupil.
- Anterior ciliary body trauma is characterized by angle recession (longitudinal tear of ciliary body face splitting circular fibres from longitudinal fibres of ciliary body). There is marked posterior displacement of the iris & wide ciliary body band posterior to the scleral spur on gonioscopy. Glaucoma is not due to recession per se but due to collateral damage to trabecular meshwork.
- Seperation of ciliary body attachment to scleral spur - cyclodialysis.
- Trabecular meshwork - trabecular meshwork tear.
- Zonules - zonular dialysis resulting in subluxation of the crystalline lens.
- Retinal attachment at ora serrata - Retinal dialysis is defined by disinsertion of the retina at the ora serrata. After trauma, most commonly the inferotemporal quadrant is involved but superonasal dialysis is pathognomonic of trauma. This is due to the fact that bilateral inferotemporal dialysis of young is a known entity which is non-traumatic.
Closed globe injury. Four phases of deformation of globe following ocular trauma by a projectile has been described. The phases are compression, decompression, overshoot and oscillation. Due to decrease in anterior posterior diameter of the globe and increase in the equatorial diamter the circumferential tissues of eye which are arranged like rings are stretched and damaged by oular trauma
- Kaushik S, Sukhija J, Pandav SS, Gupta A. Blunt ocular trauma in one eye: a photo documentation. Ann Ophthalmol (Skokie). 2006 Fall;38(3):249-52.
- Delori F, Pomerantzeff O, Cox MS. Deformation of the globe under high-speed impact: it relation to contusion injuries.Invest Ophthalmol. 1969 Jun;8(3):290-301.
- Shingleton BJ, ed. Eye Trauma. St. Louis: Mosby Year Book; 1991.