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Editor,—Pneumatic retinopexy is a promising surgical alternative in selected cases of retinal detachment.
We report a rare complication, to our knowledge the first ever reported, of this procedure—namely, hypotonic maculopathy, caused by a wound dehiscence on a patient who had previously undergone a standard extracapsular extraction with posterior chamber implant. Ultrasound biomicroscopy (UBM) proved to be a valuable adjunct in both the diagnosis and management of this complicated case.
A 63 year old white man, complaining of a shadow in his right visual field, was referred to our department in April 1997 for further management. Ocular history was notable for bilateral extracapsular cataract extraction with posterior chamber lens implantation (PC/IOL); right eye in January 1997 and left eye in June 1996. Visual acuities were 20/25 in both eyes. IOPs were within normal limits. Anterior segment examination was unremarkable with well positioned IOLs. Fundal examination of his right eye revealed a superotemporal macula on rhegmatogenous retinal detachment, produced by a single horseshoe retinal break around 10 o’clock. After the risks and benefits of pneumatic retinopexy were explained to the patient he chose to have the procedure.
Cryopexy was applied to the tear and after an anterior chamber paracentesis was performed 0.7 ml of 100% SF6 gas was injected into the vitreous cavity 3.5 mm behind the limbus inferotemporally.
He tolerated the procedure well and made an excellent recovery with the retina totally attached. He maintained a 20/30 visual acuity right eye, IOP remained within normal limits until 3 months later. At that time an IOP of 6 mm Hg and a deterioration of visual acuity to 20/70 was noted. Initially this visual loss was attributed to a posterior capsule opacification and a YAG capsulotomy was performed. Between October 1997 and November 1997 he was presented to our unit on three occasions complaining of further deterioration of vision to 20/200, IOPs between 3–5 mm Hg, and a full blown hypotonous maculopathy. After 5 months of hypotony of “unknown origin”, a diagnosis was made by a glaucoma specialist using indentation gonioscopy revealing a dehiscence of the cataract wound. A preoperative UBM study confirmed the presence of an internal wound gap, behind the limbus, superotemporally, 3 mm in circumference. Ultrasonically the wound dehiscence was depicted as a narrow slit (Fig 1) with a flat inadvertent bleb above which was not apparent clinically. A surgical repair of the wound was decided upon. Intraoperatively no definite dehiscence could be clinically identified. Balanced salt solution through a 30 gauge needle was repeatedly injected under pressure to the anterior chamber but this failed to localise any suspicious area. At this point, based on the ultrasonic study, two 10-0 nylon interrupted sutures were placed through the sclera parallel to the limbus in the suspicious area. These bites were moderately deep in an attempt to engage the internal flap of the cataract wound.
Two weeks postoperatively, the pressure normalised (IOP 12 mm Hg), maculopathy was reversed, and visual acuity improved to 20/50.
Hypotonic maculopathy is an unusual and, to our knowledge, the first reported complication1 2 of this kind after pneumatic retinopexy. We hypothesise that the original cataract wound did not heal properly and the additional cryoprobe manipulation caused the wound to leak. The UBM study provided us with an interesting insight into how the scleral suture repair may have worked to correct the wound leak as shown in Figure 2. The fact that hypotony resolved after suturing the wound, indicated that the external part of the wound was secure (no slit is apparent) despite the fact that the internal part of the wound was gaping even more postoperatively. This finding implies, therefore, that only minimal overall alteration of the wound architecture postoperatively, sufficient to rectify the leak.
We believe that UBM is a valuable adjunct in the management of similar cases by clearly identifying both the presence and exact location of leak. Finally, pneumatic retinopexy should be performed with caution, especially in cases of previously operated eyes with large incision wounds.