Pars plana vitrectomy

In the 60s, Cibis [13,14] introduced silicone oil injection in non-vitrectomied eyes. Then, Haut combined silicone oil with pars plana vitrectomy [15]. The technique was later refined by Zivojnovic [16]. Silicone oil was then used as a means of permanent internal tamponade. It was only in 1983 that Gonvers used silicone oil as a means for temporary internal tamponade [17]. 

The first study involved the eyes of 11 rabbits and 5 minipigs. We compared ocular tolerance to RMN3 with that of vitrectomied eyes. Pars plana vitrectomy was performed and followed by fluorocarbon fluid injection so as to fill more than half the vitreous cavity. Nine rabbits eyes and three minipigs eyes were vitrectomied without RMN3 injection and served as controls. Clinical examination and fundus indirect ophthalmoscopy were performed weekly until the animals were sacrificed. Enucleation was performed after 7 days in 8 rabbits eyes and after... 

The second study explored the intraocular tolerance to the mixture of RMN3-silicone oil Oxane Hd (Fig. 4) in 27 albino rabbits [8]. Pars plana vitrectomy was performed in 22 eyes with mixture injection 5 eyes received only silicone oil 1300 cSt, and the 27 adelphic eyes were used as controls. Clinical examinations were performed on D7, D30, D60 and D190, when the animals were sacrificed and tissue specimens were taken from the lower part of the ocular globes. 

K. Heimann, B. Dalh, S. Dimopoulos, K.D. Lemmen, Pars plana vitrectomy and silicone oil injection in proliferative diabetic retinopathy, Graefes Arch. Clin. Exp. Ophthalmol. 227 (1989) 152-156. 

Acetazolamide has been given during surgery to prevent lOP elevations after pars plana vitrectomy with fluid-gas exchange. No protective effect was demonstrated on lOP 4 to 8 hours after surgery or on the first postoperative day. 

A prospective nonrandomized study that evaluated aqueous and vitreous voriconazole concentrations after oral administration in 14 patients scheduled for elective pars plana vitrectomy showed therapeutic MIC90 concentrations in the vitreous and aqueous against a wide range of organisms, including Aspergillus and Candida (Hariprasad et al.). 

Jonas et al. (45) found no significant effect of intravitreal triamcinolone on blood glucose in a series of diabetic patients treated with intravitreal triamcinolone after pars plana vitrectomy for proliferative diabetic retinopathy. 

The scleral plug is a device that is implanted through a sclerotomy at the pars plana it releases the drug intravitreally (Fig. 4). Its shape is similar to that of a metallic scleral plug, which is used temporarily during pars plana vitrectomy. Controlled release of doxorubicin hydrochloride [adriamycin (ADR)] (15,16), GCV (3,4,17,19,21), fluconazole (18), 5-fluorouracil (20), and tacrolimus (FK506) (22) have been reported. 

The implant, which consisted of a 5-mg drug core surrounded by ethylene vinyl acetate and polyvinyl alcohol, was inserted through the pars plana after pars plana vitrectomy and lensectomy. The device was well tolerated and the patient s eye remained quiet and did not require any supplemental local corticosteroids. The visual acuity remained at 20/400 in the left eye and the intraocular pressure remained normal. In contrast, the patient had two episodes of recurrent anterior segment inflammation in the right eye, despite intensive topical steroids. After 10 months, the intraocular inflammation recurred in the patient s left eye, presumably because the device and surrounding tissues had become depleted of dexamethasone. 

Weiss and Bynoe (49) developed the technique of treating CRVO with pars plana vitrectomy, cannulation of a branch retinal vein and injection of tPA toward the thrombus. In a prospective study without controls, 28 eyes with CRVO of average duration of 4.9 months were treated. Baseline visual acuity was 20/63. The procedure involves a pars plana vitrectomy, elevation of the posterior hyaloid if no prior posterior vitreous detachment is noted, lowering of the intraocular pressure for the canulation of the branch vein and injection of 0.6-7.5mL of tPA (200 pg/mL). 

Quiroz-Mercado et al. (76) have described the combination of pars plana vitrectomy with posterior hyaloid detachment and formation of a chorioretinal venous anastomosis with YAG laser. It was postulated that the addition of the vitrectomy may prevent formation of preretinal fibrosis as described in previous trials. Although the initial results indicated moderate benefit in two patients, this modality requires more study. In one case study described as having a pars plana vitrectomy followed by the use of an MVR blade to create an anastomosis for the treatment of ischemic CRVO, preretinal fibrosis still developed and visual acuity improvement was minimal. 

Pars Plana Vitrectomy for Macular Edema Secondary to Retinal Vein Occlusion... 

Saika et al. (79) reported on a group of 19 eyes that had pars plana vitrectomy, elevation of the posterior hyaloid, fluid gas exchange, and cataract extraction with intraocular lens implant. Ten of the 19 eyes had decreased in macular edema as identified on optical coherence tomography the mean thickness decreased from 383 to 208 pm. However, there was no statistically significant improvement in visual acuity. If only patients with more recent onset of branch retinal vein occlusion were included in the analysis, a visual improvement was noted. 

Ascaso FJ. Transient central retinal artery occlusion following peribulbar anesthesia for pars plana vitrectomy. J Clin Anesth 2010 22 577-8. 

Two patients who presented with acute bilateral endophthalmitis following intravitreal injection of bevacizumab proved positive to Staphylococcus epidermidis when vitreous cultures were examined. One patient showed a significant improvement after injection of infravitreal antibiotics but the other patient did not improve and bilateral pars plana vitrectomy was required [110 ]. In a second similar report, a 52-year-old man given intravitreal bevacizumab developed endophthalmitis caused by S. epidermidis. The patient was managed with intravitreal antibiotics followed by pars plana lensectomy, pars plana vitrectomy with intravitreal injection of antibiotics and dexamethasone [Ill ll. 

A 67-year-old man treated by pars plana vitrectomy 15 years earlier was given intravitreal ranibizxnnab for choroidal neovascularisation. One month later, macular hole retinal detachment reoccurred [190 ]. 

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