Sir,

The appropriate management of persistent shallow retinal detachment in individuals who have already undergone surgery presents a difficult challenge for vitreo-retinal surgeons with no evidence base to guide practice. Herein, we present an interventional case report with serial optical coherence tomography (OCT) imaging and discuss potential therapeutic options.

Case report

A 78-year-old phakic Caucasian male with no past ophthalmic or medical history was referred with a retinal detachment of 1 week duration. On examination, visual acuities were counting fingers right and 6/6 left. Anterior segments and intraocular pressures were normal. Mixed lenticular opacities were present with posterior vitreous detachments and a right moderately bullous but indentable, macula-off, rhegmatogenous retinal detachment supero-temporally with a single break at 11 o'clock.

An initial nondraining cryobuckle procedure conducted under general anaesthesia the following day failed and a three-port pars plana vitrectomy with internal drainage and C3F8 gas was performed 3 weeks after the onset of initial symptoms. At day 1 postoperatively, visual acuity was counting fingers and the retina was flat over the indent with minimal subretinal fluid. At 1-month, the patient reported blurred right vision and visual acuities were 6/12 corrected right and 6/5 left. The retina was clinically attached on binocular indirect ophthalmoscopy and the treated break appeared closed. However, subclinical persistent subretinal fluid with shallow detachment of the retina was identified (Figure 1) using the OCT 3 scanner (Zeiss Humphrey Instruments, USA). The patient was managed conservatively and at 18-month follow-up visual acuity was 6/12 right with ‘puddles’ of persistent but slowly absorbing posterior pole subretinal fluid on serial OCT in different planes (Figures 2a, b).

Figure 1
figure 1

OCT demonstrating submacular fluid not detectable clinically.

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Figure 2
figure 2

OCT in different planes 18 months later demonstrating persistent subretinal fluid.

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Comment

The advent of OCT has permitted detailed visualisation of retinal anatomy and the response to medical or surgical intervention. Postoperative OCT is a particularly helpful and novel adjunct in explaining incomplete visual acuity recovery after apparent successful buckling retinal reattachment surgery, where subfoveal fluid accumulation not visible clinically or on fluorescein angiography may be identified.1, 2

The phenomenon of delayed subretinal fluid absorption causing shallow detachment presents a difficult management issue to vitreoretinal surgeons. Desatnik et al3 report a 5-year retrospective series following pneumatic retinopexy with occurence in 4.3% of cases and time to complete absorption ranging from 10 to 26 months. Possible causes include choroidal vascular insufficiency, subretinal precipitates and elevated protein content or viscosity of subretinal fluid. Additionally, abnormal retinal pigment epithelium in myopic eyes may play a role although our patient was a mild hypermetrope (R +1.00/−0.75/90 and L +1.50/−1.00/80).

While persistent subretinal fluid has been seen following nondraining procedures (as discussed above), this appears to be the first report of the phenomenon after pars plana vitrectomy with internal drainage. That this is rare, or rarely demonstrated, is supported by Wolfensberger's very recent work where OCT confirmed a 100% foveal reattachment rate with no persisting subretinal fluid 1 month following successful pars plana vitrectomy for macula-off retinal detachment in a series of 24 patients.4 Our patient underwent two procedures to repair his retinal detachment; initially an external approach with buckling, which proved unsuccessful and then pars plana vitrectomy with internal drainage, cryotherapy, and gas. Despite these interventions, he continued to have bothersome symptoms of decreased visual acuity and metamorphopsia. Additional treatment options in such circumstances may include grid argon laser to extramacular fluid collections and further surgery such as gas tamponade. However, serial OCT in our patient demonstrated decreasing subretinal fluid and so a conservative approach was taken.

In conclusion, OCT represents a novel addition to the ophthalmologist's armamentarium and serial images are helpful in the initial characterisation of shallow retinal detachment and in monitoring subsequent anatomical reattachment and the presence of subretinal fluid after surgical intervention. Importantly, it offers a new means of explaining poor visual outcome in the context of a clinically attached retina following technically successfully retinal detachment repair.