Iridodonesis

Specialty: Ophthalmology.

• tremor of the iris
• tremulous iris
• iris instability

Why it occurs

• Aphakia (biological absence of the lens, usually secondary to cataract surgery or previous expulsive trauma)
• Subluxation or complete dislocation of the lens towards the vitreous cavity or anterior chamber (associated with Marfan syndrome, homocystinuria or previous severe ocular trauma)
• Capsular pseudoexfoliation syndrome with spontaneous extreme zonular laxity
• Pathological myopia with thinning and zonular-scleral degeneration
• Previous undiagnosed direct blunt ocular trauma with silent tear of Zinn's zonule

Initial workup

Slit lamp biomicroscopy asking the patient to make rapid saccadic movements (the oscillation or tremor of the iridian stroma will be observed due to lack of posterior support of the lens); Indirect ophthalmoscopy under mydriasis to locate the exact position of the dislocated lens; Measurement of intraocular pressure using Goldmann tonometry; High-resolution ocular ultrasound or Ultrasonic Biomicroscopy (UBM) of the anterior segment to directly analyze zonular integrity.

Standard management

• There is no pharmacological treatment available to correct physical tremor of the iris. Therapeutic management is aimed at preventing or treating complications. Pilocarpine — 1% eye drops, 1 drop every 12 hours under close supervision to maintain miosis and prevent passage of a subluxated lens into the anterior chamber if the angle is open
• Dorzolamide (2% eye drops, 1 drop every 12 hours to reduce intraocular pressure if associated with traumatic ocular hypertension). The treatment of choice consists of surgical extraction of the dislocated lens (lensectomy with anterior vitrectomy) and placement of a scleral-supported or angular-supported intraocular lens.