Removal of the vitreous cells and debris in the vitreous gel may restore vision in patients with uveitis of the posterior segment (Eckardt and Bacskulin 1992; Mieler and Aaberg 1992; Heimann et al. 1992; Kaplan 1992; Diamond and Kaplan 1979). Intermediate uveitis may be complicated by vitreous haemorrhage that can be treated successfully by ­vitrectomy (Potter et al. 2001). Many of these patients are young and have attached PHM, which will require removal, but the PHM may be difficult to detach because of vitreoretinal adhesions. Postoperatively the eye may produce inflammation requiring systemic immunosuppressive cover over the peroperative period. Visual recovery is often limited because of the presence of optic atrophy or retinal damage particularly from CMO (Verbraeken 1996; Waters et al. 2000). Some surgeons claim that removal of the gel reduces the ability of the eye to hold inflammatory mediators and thereby reduces recurrence of inflammation in the long term. Evidence for this remains uncertain (Bovey and Herbort 2000). Others argue that improvement following surgery is a result of the removal of vitreous opacity rather than any influence on the inflammatory process (Mieler et al. 1988). Also reduction in medical treatment after surgery has been blamed for a rebound of inflammation 3–6 months later. Therefore, PPV is not recommended routinely in these patients but is reserved for the treatment of the vitreoretinal complications.

Retinal vasculitis can produce ischaemia and a neovascular response associated with vitreous haemorrhage. PPV can be used to relieve traction to prevent recurrent haemorrhage and clear the visual axis. Unlike diabetic retinopathy, panretinal photocoagulation is not universally required.

When TRD is associated with neovascularisation or fibrosis, delamination and dissection of the membranes are required. A vitreoschisis, as seen in diabetic retinopathy (Chap. 9), may be present and must be recognised to allow appropriate dissection under the plane of the PHM to aid delamination. Unfortunately TRDs are often associated with severe subretinal exudation in uveitic eyes, and visual recovery is often poor.

Rarely patients present with TRD without neovascularisation or preretinal fibrosis; a smooth elevation of the retina is seen. PPV and peeling of the PHM will suffice, allowing the retina to settle without need to drain SRF.

RRD may occur from PVD formation and can be dealt with by routine means (see Chap. 6) whilst being aware of the possibility of exacerbation of the uveitis.

Exudative RD may be encountered and diagnosed by shifting fluid and the absence of retinal tears, traction and epiretinal fibrosis (despite a long-standing duration of retinal detachment) (Gaun et al. 2002). Beware that the patient does not have uveal effusion syndrome. If immunosuppressive therapy does not reattach the retina, PPV a retinotomy to drain the SRF or an external drainage may help. During the surgery, the exudative nature of the retinal detachment can be confirmed by inserting heavy liquids onto the posterior retina. This will displace SRF anteriorly where it is trapped (because there is no retinal hole to allow drainage) and forms a tight ring bulla which overhangs the heavy liquid. Removal of the heavy liquid reveals a return of the retinal detachment to its previous configuration, confirming no loss of SRF. Perform a small and peripheral retinotomy to drain SRF and laser the retinotomy. Alternatively bend a needle as for an external drain (see DACE procedure, Chap. 6) whilst viewing the retina internally via PPV and indent the sclera gently with the ‘heel’ of the bend in the needle to locate its position. Locate the needle into an area of high SRF (fill the posterior pole with heavy liquid to create a ring bulla), then rotate the needle to insert the point through the scleral and choroid to commence drainage. With small-gauge surgery, the needle can be inserted through the conjunctiva. Fill with long-acting gas or silicone oil. If the uveitis is then controlled, return of the retinal detachment is unlikely.

Steroid injections into the vitreous cavity can reverse CMO in uveitis. However, the chronic nature of these conditions causes a return of the CMO after the steroid has been cleared from the eye (Antcliffe et al. 2001). Slow-release steroid implants or injections may overcome this difficulty and are now available. For example, slow-release dexamethasone pellets can be injected as an outpatient procedure; they have an effect for 3–6 months similar to intravitreal triamcinolone but appear to have less chance of an IOP rise (Haller et al. 2010a, b). PPV has been performed to try to relieve traction on the macula to resolve cystoid macular oedema (Dugel et al. 1992; Verbraeken 1996; Aylward 1999) because the vitreous is more often attached than not in patients with CMO (Davis et al. 1992). Others have examined the severity of cystoid macular oedema and found both improvement (Heiligenhaus et al. 1994; Tranos et al. 2006) and persistence of the complication following vitrectomy (Diamond and Kaplan 1978; Priem et al. 1993). Separating the response to vitrectomy from the natural history of the condition and from the effects of concomitant therapies is difficult because randomised studies have not been done.

Hypotony occurs in these eyes because the ciliary body becomes involved in the uveitic process.

Causes of ciliary body failure:

Vitrectomy has been used to try and relieve traction on the ciliary body in hypotony (Kaplan 1992). Inspection of the ciliary body with dissection of any tractional membranes has been performed only in a few patients and is as yet of ­uncertain worth especially as often the ciliary processes are atrophic and may be non-functional. Insertion of hyaluronic to provide a temporary IOP rise has been employed. Silicone oil can be used for a more prolonged effect and to prevent severe shrinkage of the size of the eye if hypotony persists (Morse and McCuen 1991). Long-term results of these ­interventions are unknown.

Use transconjunctival 23 or 25 gauge if possible inserted at 4 mm from the corneal scleral limbus; if not available, create the usual 20-gauge sclerotomy opening inferotemporally (see Chap. 2).

A table of immunosuppressive agents that can be used in the treatment of uveitis.

Insert the cutter and visualise in the eye.

Maintain the IOP with a squint hook providing scleral indentation whilst employing the cutter to extract the vitreous to beyond the three-way tap (inserted on the first junction of the aspiration tubing), providing approximately 0.5 ml of vitreous.

Remove the cutter and reinflate the eye with any intravitreal drug administration, for example, antibiotics, whilst relieving the pressure on the squint hook.

Sew up the sclerotomy and conjunctiva if 20 gauge.

Remove the sample from the tubing to send to the laboratory. Take an anterior chamber sample via a paracentesis as required.

If a small sample is required at the beginning of a PPV, the sample needs to be ‘dry’, that is, not diluted with the infusion fluid; therefore,

At the end of the PPV after closing one sclerotomy and with the infusion switched off, insert any intravitreal ­injections, close the other sclerotomy and then remove the infusion cannula.

Viral infections of the retina cause a mixed arteritic and infiltrative retinitis. The causative viruses are commonly of the herpes simplex family (Akpek et al. 1999a).

Herpes simplex 1 is commoner in the young age group (Rahhal et al. 1996; Lewis et al. 1989).

These patients may have a history of cold sores.

Herpes zoster is commoner in the elderly (Freeman et al. 1986; Bali et al. 2003; Zambarakji et al. 2002) and can be associated with herpes zoster ophthalmicus (Nakanishi et al. 2000) and chicken pox (Culbertson et al. 1991).

Herpes simplex 2 infections can also occur especially in children (Rahhal et al. 1996; Markomichelakis et al. 2001; Rappaport and Tang 2000).

Epstein–Barr virus can rarely be detected but is often considered to be a coincidental finding (Hershberger et al. 2003).

Patients are generally not immunocompromised, but herpes zoster is implicated in both ARN (Hershberger et al. 2003; Weinberg and Lyon 1997) and progressive outer retinal necrosis in AIDS patients (Purdy et al. 2003; Austin 2000; Moorthy et al. 1997; Perez-Blazquez et al. 1997; Pavesio et al. 1995; Margolis et al. 1991) and the immunocompromised.

There is a significant risk of bilateral disease (Ezra et al. 1995; Martinez et al. 1992) with fellow eye involvement even years later (Matsuo et al. 1987) and a long-term risk of encephalitis (Ahmadieh et al. 1991; Bloom et al. 1977).

The retina has the appearance of peripheral haemorrhage and infiltration, which spread posteriorly to involve the macula, but the presentation has variable severity (Bloom et al. 1977). The retina may become moth eaten, and retinal detachment is common up to 50 % (Carney et al. 1986). In severe presentations, exudative retinal detachment can occur (Duker et al. 1990). Patients have been described with giant retinal tears (Topilow et al. 1982), retinal neovascularisation (Wang et al. 1983) and peripheral retinal pigment epithelial tears (Fox and Blumenkranz 1993). Proliferative vitreoretinopathy is common.

The prognosis for vision is poor in the affected eye; therefore, systemic therapy is essential to prevent involvement of the other eye.

Cytomegalovirus (CMV) infects the retina in immunocompromised patients. Overwhelmingly these patients suffer from AIDS. Prior to highly active antiretroviral therapy (HAART) (Jabs 1995), 40 % of AIDS patients developed CMV retinitis. Others requiring systemic immunosuppression such as Wegener’s granulomatosis or rheumatoid arthritis are occasionally present (Akpek et al. 1999a; Fraenkel et al. 1995). Classically in AIDS, the patient has a severe reduction in CD4 white blood cells to less than 50 cells/μl. With the introduction of HAART, control of viral load is much improved, and consequently CD4 counts are more often preserved. This has led to a massive reduction in the numbers of new cases of retinitis which may only occur when there is failure of or resistance to HAART (Uphold et al. 1998; Mitchell et al. 1999; Mocroft et al. 2000; Jalali et al. 2000). Retinal detachment was a common complication of the retinitis before HAART (50 % at 1 year after development of retinitis (Jabs 1995; Jabs et al. 1991)), usually slow in onset because of the presence of a formed and attached vitreous gel in these young patients, and bilateral in 70 % (Sidikaro et al. 1991). Prior to HAART, this was linked to early mortality at approximately 6 months (Dugel et al. 1991; Irvine et al. 1997). Since HAART, patients with CMV retinitis have shown 81 % reduction in mortality (Kempen et al. 2003) and 60 % reduction in retinal detachment (Kempen et al. 2001), but most with CMV retinitis will develop a condition called immune recovery uveitis which can reduce vision (Holbrook et al. 2003; Arevalo et al. 2003; Song et al. 2003). This is characterised by posterior segment inflammation which causes secondary complications such as cystoid macular oedema (Irvine et al. 1997), vitreomacular traction (Canzano et al. 1998), vitreous haemorrhage from retinal neovascularisation (Wright et al. 2003), and even activation of previously quiescent infections of the retina such as mycobacteria (Zamir et al. 2002).

Note: Immune recovery uveitis is usually self-limiting causing only mild visual loss.

Increasingly, the control of the viral load is most important to the control of the retinitis by allowing cessation of anti-CMV therapy as the CD4 count recovers (Wright et al. 2003).