A 70-year-old man presented to ED for reduced vision in his right eye which was worse when lying supine. The man had sustained a head injury two days previously. His visual acuity was 6/18 in his right eye and 6/6 in his left eye. Intraocular pressure was normal.
A CT head non-contrast was performed given the nature of the patient's head injury. The CT scan demonstrated a right lens subluxation and a pseudophakic left eye. The right lens was subluxed posteriorly and superior - medially. No other acute intracranial pathology was identified. The slit-lamp examination, with the patient seated and vertical, demonstrated that the right lens had returned to the anatomical position, thus preserving vision. The patient's left eye had previously had a cataract removed and an intraocular lens inserted, explaining the pseudophakic appearance on CT.
Lens dislocations or subluxations are most commonly associated with traumatic injuries . They are, however, a rare complication of head injury . The term ectopia lentis is also used to describe the condition. Ectopia lentis includes any cause or association which leads to displacement or malposition of the crystalline lens . Atraumatic dislocations are seen in some congenital connective tissue diseases such as Marfan’s, homocystinuria, hyperlysinemia, sulfite oxidase deficiency, simple primary ectopia lentis, congenital aniridia syndrome and Ehlers-Danlos syndrome [1, 3]. Other ocular, atraumatic causes include staphylomas, ectasias, buphthalmoses, high myopia, hyper-mature cataract and syphilis . Dislocation or subluxation is also seen in zonular dehisence after cataract surgery . The lens can dislocate into both the anterior and posterior chambers . Posterior dislocations are more common. Lens dislocations or subluxations initially present with visual changes such as reduced visual acuity or diplopia . They can present with pain in acute angle glaucoma secondary to anterior dislocations. If left untreated, lens dislocations can lead to complete visual loss. Other complications include retinal detachment and cataract .
CT is an excellent diagnostic modality in lens dislocation with the lens being clearly visible . Ultrasonic biomicrosopy can be used to assess the degree of zonular compromise but should be avoided in cases of suspected globe rupture [2, 3].
Treatment is mostly surgical and prompt referral to an ophthalmology service is crucial . The lens can be replaced, explanted or re-positioned. There are multiple surgical options for managing subluxed or dislocated lens, and no consensus exists as to which is the superior approach or technique . Anterior lens dislocation is an ophthalmological emergency as it can interfere with the drainage of aqueous humour and cause obstruction and acute angle closure glaucoma .
In this case, given that the patient's vision was well preserved while standing and sitting and in his activities of daily living, surgical intervention was deferred. He was booked in for an elective right lensectomy and intraocular lens insertion, which can be expedited if his visual acuity deteriorates.
The case highlights the importance of appropriate and prompt imaging in case of suspected lens dislocations and subluxations. The CT scan provided the diagnosis, as the lens subluxation was only present with the patient lying supine, and it guided the management. Accurate clinical history and examination are of the utmost importance, especially in cases where incidental findings, such as a pseudophakic lens, exist.
Differential Diagnosis List
Traumatic right lens subluxation
Right lens dislocation
Atraumatic lens dislocation / subluxation
Traumatic right lens subluxation