5.6 Ultrasound

Fig. 5.8 A subretinal haemorrhage from a Valsalva manoeuvre

5.6Ultrasound

All vitreoretinal clinics should have ultrasonography available. If the surgeon learns this skill, he or she will be able to make rapid assessment and diagnosis of the eye by interpreting information on the dynamics of the vitreous and the retina. In vitreous haemorrhage, first determine whether the retina is flat by taking cross sections of the whole eye. A sinuous continuous high echo which starts at the ora serrata and ends around the optic nerve head is typical of detached retina. In contrast, a posterior vitreous detachment will move with a more rapid and flimsy action. If the vitreous is detached, watch out for the flap of a retinal tear attached to the peripheral vitreous; a sensitivity of 56 % has been estimated for detecting retinal tears on ultrasound in eyes with vitreous haemorrhage (Tan et al. 2010). There may be an attachment of the vitreous to the disc if disc new vessels are present in diabetes or with BRVO, but most often there is no

attachment at the disc. Diffuse increased echo behind the gel indicates retrohyaloid blood. If this is seen behind a high echo membrane, which may appear like retina, it helps identify the membrane as thickened posterior cortical vitreous gel. In comparison, retinal detachments have clear fluid on ultrasound behind their echogenic signal, that is, SRF in the subretinal space. If the vitreous is still attached, this may aid in diagnosis suggesting diabetic retinopathy or an unusual cause such as Terson’s syndrome (Chap. 16). The focal attachments of an otherwise detached vitreous can be helpful, for example, the vitreous attached to new vessels at the disc or elsewhere, tractional retinal detachments or incarceration sites in trauma or needlestick injury.

Other conditions will provide clues of their own. Choroidal neovascular membranes that bleed tend to produce severe subretinal haemorrhage which can be seen as a dense immobile craggy mass at the posterior pole. The patient will usually have signs of high-risk age-related macular degeneration in the other eye, for example, soft drusen or disciform scar.

Tumours have their own characteristic shapes, for example, collar stud melanoma. Colour Doppler imaging helps by demonstrating a tumour circulation in elevated, for example, metastases and malignant melanomas. Vasoproliferative tumours are flatter and more difficult to detect with Doppler.

Retinoschisis provides a thin dome-shaped peripheral elevation. X-linked retinoschisis is particularly associated with vitreous haemorrhage in the young.

Ultrasound features:

•Vitreous detached or not

–If attached not a retinal tear!

•Evidence of neovascularisation

–BVO or CRVO.

–But beware the posterior retinal break which can be attached to the gel and look like posterior neovascularisation.

•Subretinal haemorrhage

–Large craggy mass under the retina.

–CNV can be posterior or peripheral.

Mass / new vessels

Tear / RDD /

nil

5.8Surgery

Mild vitreous haemorrhage may clear spontaneously. Depending upon the aetiology, recurrences can occur. Monitoring is required to detect retinal detachment or erythroclastic glaucoma. If the

surgeon determines that there is a risk of retinal detachment, early vitrectomy is advisable to allow inspection of the retina and treatment of any breaks. It is advisable to have a low threshold for performing PPV when the diagnosis is uncertain because of the significant risk of retinal detachment.

Fig. 5.12 When removing very dense blood during PPV, create a small peripheral hole in the posterior vitreous and flush out the retrohyaloid blood to clear the view and to identify the retina, before removing the rest of the gel

Fig. 5.13 This macroaneurysm has bled into the vitreous cavity

Table 5.1 Difficulty rating of PPV for vitreous haemorrhage

5.9Vitrectomy

Additional surgical steps:

•Remove the core vitreous, and make a perforation in the posterior hyaloid.

•Remove any retrohyaloid haemorrhage through the perforation.

•Remove the remaining vitreous.

•Find the cause of the haemorrhage and treat appropriately. Checking if the infusion has penetrated can be difficult

because of overlying blood. Make sure that you can see the infusion by removing haemorrhagic vitreous around the cannula before switching on the infusion (see clearing the infusion Chap. 2). Start by removing the core vitreous to clear a view. If the eye has PVD, make a hole in the posterior hyaloid membrane (PHM) and drain out any subhyaloid haemorrhage.

•This allows visualisation of the retina to check that it is attached and not at risk of damage whilst you remove further vitreous.

•Failure to remove the subhyaloid haemorrhage allows the haemorrhage to mix with the infusion fluid, causing repeated loss of the view during the remaining vitrectomy. Once the vitreous has been removed, trim the vitreous

base to leave as little haemorrhage in the eye as possible. There is usually a clear layer of vitreous in the denser cortical gel next to the retina which gives you a clue when to stop removing gel before hitting the retina. Residual haemorrhage leaks out postoperatively and can cause erythroclastic glau-

Fig. 5.14 This patient presented from the intensive care unit with suspected bilateral endogenous endophthalmitis, with absent anterior chambers with white infiltration. It was diagnosed later that the patient had probably suffered severe intraocular haemorrhaging from severely reduced platelets, presumably causing choroidal haemorrhage (with anterior chamber shallowing), followed by vitreous and then anterior chamber haemorrhage (white old blood clot). The patient regained 20/20 vision over the course of a year after anterior segment reconstruction, vitrectomy and later penetrating keratoplasty. Images show the right eye preoperatively and postoperatively (anterior segment and fundus) and the untreated left eye (see Figs. 5.15–5.17)

coma. In addition, good clearance of the vitreous base allows full inspection of the retina. The cause of the haemorrhage should be determined and treated such as retinopexy and gas for retinal tear or detachment, or laser therapy for vein occlusion.

Fig. 5.15 See previous figure

Fig. 5.16 See Fig. 5.14