Background: The recent development of 20- and 19-gauge diameter endoscopes allows an excellent direct intravitreal visualization of intraocular morphology. A gradient index (GRIN) endoscope (Insight Instruments, Lake Mary, FL, USA), which combines a small diameter (0.89 mm, 20 gauge) and an exceptional optical resolution, can be used as a diagnostic tool for the assessment of the safety and vitreous interaction of sustained release intraocular devices which have been designed to deliver ganciclovir (Vitrasert) over a period of 8-12 months and were successively implanted in several eyes.
Patients and methods: 78 eyes of 49 patients received 100 ganciclovir implants between November 1995 and July 1998. In six patients who received additional implants, the GRIN endoscope was used as an optical control of wound healing processes and Vitrasert positioning after implantation of prior devices (two-point suturing technique).
Results: In all of these six eyes, a clinical stabilization of the cytomegalovirus retinitis was noted. Endoscopic observation of the scleral 5-mm incision revealed no gaps after two-point suturing of the device. Only one of six eyes showed significant vitreous tractions around the Vitrasert. However, the struts of all pellets were completely covered by a fibrous membrane. Occasional fibrous plaques were noted on the surface of devices which presumably had been damaged by surgical manipulations. In one case, the endoscopic examination disclosed the suprachoroidal implantation of a device. In this eye, no signs of retinal toxicity or recurrence of CMV retinitis were observed.
Conclusions: High resolution endoscopy of the vitreous cavity appears to be an effective method for the control of intraocular drug delivery devices. Basically, the repeated implantation of intraocular ganciclovir implants can be considered a safe method in the management of relapsing CMV retinitis. However, the endoscopic observation of fibrous membranes covering the struts suggest that the explanation of an intraocular device has the potential for various intraoperative complications (e.g. hemorrhages, traction, tears, retinal detachment). Therefore, we would recommend the additional implantation of further implants rather than a replacement.