Causes and risk factors
Causes of subluxation of lens are – congenital ectopia lentis [congenital bilateral subluxation of lens]. Acquired causes include excessive stretching of zonules, degeneration of zonules, and tear of zonules due to trauma or penetrating injury, sports injury, severe blow to the eye or head injury, or accidents. It can occur as a result of major eye surgery.
Clinical presentation
Patient presents with symptoms such as mononuclear diplopia [double vision in one eye], dimness of vision, myopia [short sightedness]. Loss of accommodation is experienced. Signs like unequal depth of anterior chamber, vibration or tremulousness of iris on movement of the eye [iridodonesis] or lens [phacodonesis]. During ophthalmoscopic examination, the edge of lens is visible as dark crescentic line. Indirect ophthalmoscopy may show 2 images of disc due to phakic and aphakic zones in the pupil. Secondary glaucoma may be present in some cases. Photophobia, eye pain, or headache may be the accompanied symptoms.
Investigation
Medical history by the patient and clinical examination by the ophthalmologist helps in diagnosis. Routine ophthalmic examination is done. Visual field testing is recommended.
Treatment
If the lens remains clear and there is no irritative symptom, treatment involves use of glasses to correct the phakic part. Contact lenses to correct vision will also help in managing the condition. In presence of cataract or irritative symptoms, for small zonular tear, extracapsular cataract extraction [ECCE] with posterior chamber intraocular lens [PC IOL] is considered. A capsular tension ring is helpful in some cases. If the zonular tear is more, intracapsular cataract extraction is the treatment of choice followed by anterior vitrectomy. Sometimes scleral fixation posterior chamber -SC PC IOL may be considered.
