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Editor,—A symptomatic retinal tear with vitreous traction is an indication for vitreoretinal surgery. In patients with opaque ocular media—that is, cataract or vitreous haemorrhage, it is almost impossible to observe these retinal abnormalities. Preoperative standardised echography helps to locate and assess the retinal tear and to evaluate the surrounding retina. In the presence of opaque ocular media and echographic evidence of retinal tear with a flat retina, there are three possible treatments: (1) when the ocular media is clear enough, laser photocoagulation may be performed around the hole; (2) with prolonged vitreous haemorrhage, pars plana vitrectomy can be performed with endolaser; and (3) with advanced cataract, cataract extraction can be performed with laser. A new treatment approach has been suggested by DiBernardo et al 1 and later by Kelly et al. 2 Kelly and associates described 11 patients with dense vitreous haemorrhage which obscured the retinal tear from direct visualisation; ultrasound guided cryotherapy was performed.
A 56 year old man was examined in our outpatient clinic because of an acute decrease in visual acuity to hand movement in his left eye. In the past, the patient had undergone several laser photocoagulation treatments for retinal tears in both eyes. Slit lamp examination revealed a dense vitreous haemorrhage obscuring the retina. Intraocular pressure was in the normal range. A-scan at tissue sensitivity (Fig 1A) and B-scan ultrasound demonstrated a flat retina with a flap retinal tear located anterior to the equator at 6 o’clock (Fig 1B). The vitreous was adherent to the anterior margin of the tear and freely moved with eye movements. Right eye visual acuity was 6/6, with no ocular abnormalities. The patient was observed over 10 days and no ocular echographic changes were detected. At this stage, we performed ultrasound guided cryotherapy to the retinal tear. Under topical anaesthesia, the retinal break was detected by B-scan ultrasound and a cryoprobe was positioned on the scleral surface at the site of the retinal break. The cryoprobe indentation, closure of the tear, and ice ball formation could be demonstrated in real time on the display screen under full control of the surgeon (Fig 2). A few applications were performed directly on the retinal tear and to the adjacent retina under B-scan ultrasound visualisation of ice ball formation at the treated site. Four weeks later, the vitreous was clear, the retina was flat and the tear was surrounded by scar.
Ultrasound guided cryotherapy is an effective treatment for single flap retinal breaks in the presence of vitreous haemorrhage or advanced cataract obscuring direct view of the retina. Some of the patients may need laser photocoagulation after partial clearing of the vitreous haemorrhage in addition to the first treatment. Cryotherapy is inappropriate for eyes with round atrophic holes that could be missed by ultrasound. We are currently comparing the ophthalmoscopic appearance of an ice ball formation with that on echography to control the cryoapplication duration, and the amount and extent of retina treated.
This is a low cost, ambulatory procedure which is painless and relatively non-invasive compared with other methods. Further study with ultrasound guided cryotherapy is needed in cases of retinal breaks obscured by opaque ocular media.
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