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Sir,

The indications for removal of a scleral explant include extrusion, migration, infection, excessive height, pain, diplopia and visual disturbance. The frequency of explant removal in published series varies from 1.2 to 24.4%,1,2,3,4,5,6,7 and the retinal redetachment rate following this varies from 3.2 to 47%2,3,4,5,6,7,8,9 (follow-up ranging from 6 months to 4 years). Reopening of the original tear is the cause of retinal redetachment in most cases.

Following explant removal, it is rare for a new retinal tear to open, and when this happens, the break is usually close to the original break. We report a patient who developed a new retinal tear (and retinal detachment) 6 clock hours away from the original retinal tear.

Case report

A 48-year-old myopic patient (−5.75/−3.50×15 right and −3.75/−4.00×167 left) presented with an acutely symptomatic retinal detachment (RD) in his right eye. The retina was detached from 1 to 5 o'clockbecause a peripheral U-shaped tear at 1 o'clock. The macula was attached, and corrected visual acuity was 6/6 in the right eye and 6/5 in the left.

A diagnosis of pigment dispersion syndrome had been made 6 years ago, and at that time bilateral posterior vitreous detachments (PVD) were also noted.

The RD was repaired on the day of presentation under general anaesthetic. Subretinal fluid was drained, cryotherapy was applied, and 20% sulphur hexafluoride gas was injected. A ♯276 segmental circumferential silicone explant was then sutured to the sclera in the supero-nasal quadrant. Early postoperative progress was satisfactory, with a flat retina and high indent. However, 2 months following surgery he complained of foreign body sensation and irritation at the site of the explant, which was found to be extruding. After 1 month, the explant was removed under general anaesthetic.

At a routine clinic visit 6 weeks later, a new and peripheral RD was found infero-temporally in the right eye. A peripheral U-shaped tear was identified at the 7 o'clock position, 6 clock hours away from the sealed original tear.

A three-port pars plana vitrectomy was carried out, with internal drainage of subretinal fluid, 30% sulphur hexafluoride exchange, and indirect laser photocoagulation around the tear. The retina has since remained attached.

Comment

The rate of retinal redetachment following scleral explant removal in published series varies from 3.2 to 47% (follow-up ranging from 6 months to 4 years). Several of these are summarised in Table 1.

Table 1 Results of published series of retinal detachment following explant removal
Full size table

Lindsey et al8 reported recurrence of RD in 20 of 53 patients (47%), with a follow-up period of 4 years. Three of these cases had new tears, although their location is not mentioned. Deutsch et al7 reported 61 cases of explant removal, five of whom (8%) subsequently redetached. In two of these cases, the redetachment was a result of new inferior breaks. In the first case, the original surgery was performed for a localised upper-half RD with no identifiable break. After explant removal, the eye developed a new RD of the lower retina, with an apparently new U-shaped tear at the 6 o'clock retinal periphery. In the second case, the new break was inferior and 6 clock hours away from the original group of round breaks.

In contrast to the above reports, new retinal breaks are well described following pneumatic retinopexy.10,11 In the Poliner et al12 series of 13 cases of RD treated with pneumatic retinopexy, two cases had new retinal breaks adjacent to the original tears and two cases had new retinal breaks 5–6 clock hours away from the original tears. They postulated that the buoyant gas bubble created vitreous traction on the inferior retina in the meridian of the involved tears. Snead13 has suggested that a gas bubble expanding behind a detached posterior hyaloid membrane may be particularly likely to cause such breaks. In our patient, a new U-shaped tear 6 clock hours away from the original tear caused a second RD. This suggests that the original explant had been relieving trans-vitreous traction, and following explant removal the recurrence of this vitreous traction caused a new tear. It is tempting to speculate that the PVD 6 years previously was incomplete, accounting for both the delayed presentation of the original RD, and also the persistent vitreo-retinal traction leading to a new RD after explant removal.

New retinal detachment following scleral explant removal is rare, and is likely to be at the area of maximal vitreous traction either around the original hole or approximately 180° away from it.