A two-stage technique for intraoperative fluid-gas exchange following pars plana vitrectomy

Measurement of the volume of the vitrectomized space during vitrectomy in myopic patients with retinal detachment

PURPOSE

We present a novel technique for measuring volume of space replaced by air during fluid-air exchange in vitrectomy (vitrectomized space) for intravitreal gas injection. To confirm the feasibility of this technique, we assessed postoperative intraocular pressure (IOP) and the duration of injected gas. Using this technique, we found remarkable differences in volume between high myopic eyes with retinal detachment caused by peripheral break (PB-RD group) and those with macular hole retinal detachment (MH-RD group). We studied the relationships between the volume and biometric values, axial length (AL) and corneal curvature radius (CCR) in both PB-RD and MH-RD group.

STUDY DESIGN

Retrospective study.

METHODS

During fluid-air exchange, the aspirated fluid accumulates in the measuring cup between the infusion needle and vitrectomy instrument. Vitrectomized space volume is obtained by subtracting the volume of the tube between the infusion needle and the 3-way stopcock from the aspirated fluid volume. We performed phaco-vitrectomies by measuring the vitrectomized space volume and then injected pure SF6 at 15% of the volume into the vitreous cavity in 156 myopic eyes (AL > 26 mm) with RD consisting of 144 eyes in PB-RD group and 12 in MH-group.

RESULTS

The IOP (mean ± SD) was 13.5 ± 3.4 mmHg preoperatively, 23.4 ± 10.4 mmHg on day 1, 18.2 ± 7.4 mmHg on day 2, and 16.1 ± 4.5 on day 7. The gas disappeared in 16.1 ± 1.9 days. Axial length was longer in the MH-RD group but the volume of vitrectomized space was larger in the PB-RD group. AL and volume were significantly correlated in both groups (P < 0.01), but the fitting lines differed. The CCR and volume significantly correlated in the PB-RD group (P < 0.01) but not in the MH-RD group.

CONCLUSION

Our novel technique for measuring the volume of vitrectomized space can achieve target gas concentration in the vitreous cavity. The difference in the shape of eyeballs may explain discrepancies in relationship between volume and the biometric factors.

An Office-Based Fluid to Fluid Exchange Technique for the Treatment of Postvitrectomy Vitreous Cavity Hemorrhage and Secondary Glaucoma

A case of postvitrectomy hemorrhage with secondary glaucoma successfully treated with an office-based fluid to fluid exchange is described. A 25 Ga trocar was placed 3 mm from the sclerocorneal limbus at the 2 o'clock position and connected to a 250 cc elevated bottle of balanced salt solution (BSS) through an intravenous (IV) line and an infusion cannula. Afterward, a 25 Ga needle was inserted 3 mm from the limbus at the 5 o'clock position approximately. The BSS fluid entered the eye through the 25 Ga trocar lavaging the vitreous cavity and the anterior chamber. About 4 to 6 cc of hemorrhagic fluid egressed the eye through the 25 Ga needle.

Intravitreal Fluorinated Gas Preference and Occurrence of Rare Ischemic Postoperative Complications after Pars Plana Vitrectomy: A Survey of the American Society of Retina Specialists

Objective. To perform a survey of the American Society of Retina Specialists (ASRS) regarding the use of vitreous cavity fluorinated gas as an adjunct to pars plana vitrectomy for retinal detachment or macular hole repair. Methods. A multiple-choice online questionnaire was administered to members of ASRS. Physician experience, gas preference for vitrectomy, and categorical estimate of observation of blinding postoperative ischemic events were recorded. Results. 282 questionnaires were completed. Mean years in vitreoretinal practice were 15 ± 10. A decrease in yearly vitrectomy volume was associated with increased number of years in practice (P = 0.011). Greater than 95% of respondents preferred fluorinated gas to air alone for both retinal detachment and macular hole repair. 38% of respondents reported at least one observation of a blinding ischemic postoperative event. Overall estimated incidence of blinding postoperative ischemic event was 0.06 events/year in practice. Conclusions. Currently, C3F8 and SF6 are the postoperative gas preference for ASRS respondents, in contrast to previous North American surveys. The occurrence of blinding ischemic events appears unrelated to number of years in practice, was reported by less than half of those surveyed, and has occurred at an infrequent rate of approximately once for every ten years of practice for those observing the phenomena.

Management of postvitrectomy diabetic vitreous hemorrhage with volume homeostatic fluid-fluid exchanger

BACKGROUND

To evaluate the clinical outcome of patients with postvitrectomy diabetic vitreous hemorrhage (PDVH) who underwent vitreous cavity lavage (VL) by volume homeostatic fluid-fluid exchange.

METHODS

We performed a retrospective chart review for 88 eyes of 80 consecutive patients who underwent VL for PDVH. Final best-corrected visual acuity after VL was compared to those before VL. Anatomic outcome, including rate of fundus clear-up, recurrent vitreous hemorrhage, increased intraocular pressure, iris neovacularization and anterior hyaloid fibrovascular proliferation were considered.

RESULTS

Between July 1999 and January 2006, 88 eyes of 80 patients underwent this procedure. Significant visual improvement was observed after VL (2.86 +/- 0.40 logMAR at baseline vs 1.71 +/- 0.97 logMAR at last visit, p < 0.0001). The fundus clear-up rate after VL was achieved in 84 out of 109 times (77.1%). Recurrent vitreous hemorrhage was found in 17 of 88 eyes (19.3%) with the mean interval of 92.6 +/- 126.7 days after VL.

CONCLUSIONS

For patients suffering from postvitrectomy diabetic vitreous hemorrhage, volume homeostatic vitreous cavity lavage can be an alternative method for removing the bloody content in the vitreous cavity efficiently and permitting rapid visual recovery.

Primary pars plana vitrectomy versus scleral buckle surgery for the treatment of pseudophakic retinal detachment: a randomized clinical trial

OBJECTIVE

To compare the anatomical and functional outcome of scleral buckle (SB) surgery with that of pars plana vitrectomy (PPV) alone in the treatment of primary rhegmatogenous pseudophakic retinal detachment (RD).

METHODS

In this prospective, randomized clinical trial, 150 eyes of 150 patients with pseudophakic RD and proliferative vitreoretinopathy (PVR) stage B or less were randomized to SB surgery (75 eyes) or primary PPV (75 eyes). SB surgery involved break localization, cryotherapy, placement of a circumferential 240 style 2.5-mm solid silicone band, combined with a local buckle when indicated, and transscleral drainage of subretinal fluid. PPV included extensive vitreous removal, perfluoro-n-octane injection or endodrainage of subretinal fluid to flatten the retina, cryopexy treatment of breaks, and fluid/air exchange with injection of 20% SF6. Postoperative follow-up was 1 year. Break diagnosis, operating time, intraoperative and postoperative complications, retinal reattachment rate for single as well as multiple surgeries, axial length changes, and best-corrected visual acuity at 1 year after surgery were the main outcome measures.

RESULTS

The number of eyes that were diagnosed with additional breaks inter-operatively was higher in the PPV group (P=0.004, chi test). Mean operating time was significantly less (P=0.0001, t-test) in the PPV group. With a single surgery, the retina was reattached in 62 eyes (83%) in the SB surgery group and in 71 eyes (94%) in the PPV group (P=0.037, Fisher exact test). With subsequent surgeries, final anatomical reattachment was achieved in 71 cases in the SB surgery group and in 74 cases in the PPV group (P=0.37, Fisher exact test). Mean axial length change at 1 year was 0.95 mm in the SB surgery group and 0.1 mm in the PPV group (P=0.0001, t-test). Mean final best-corrected visual acuity (logMAR) was 0.40 in the SB surgery group and 0.33 in the PPV group (P=0.26, t-test).

CONCLUSIONS

Primary PPV offers potential advantages over SB surgery in the treatment of pseudophakic RD, including less operating time, accurate diagnosis of breaks, higher reattachment rate with a single surgery, and no postoperative axial length changes. Retinal reattachment rate with multiple surgeries and final visual acuity at 1 year were similar for SB surgery and PPV.

Management of postvitrectomy diabetic vitreous hemorrhage with tissue plasminogen activator (t-PA) and volume homeostatic fluid-fluid exchanger

The incidence of recurrent vitreous hemorrhage of proliferative diabetic retinopathy following posterior vitrectomy ranges from 29% to 75% in reported series. Fluid-gas exchange and vitreous cavity lavage are the popular methods of treating this kind of recurrent hemorrhage. The fluid-gas exchange cannot offer clear vision immediately after the procedure. To improve the function of the classic vitreous cavity lavage, we designed a volume homeostatic fluid-fluid exchanger - Chen's I/A device. Tissue plasminogen activator (t-PA) is a protease that preferentially converts fibrin-bound plasminogen to the active proteolytic enzyme, plasmin. It has been clinically and experimentally proven effective in lysis of postvitrectomy blood clot and fibrin formation. When the blood clot is formed in the vitreous cavity, intravitreal injection of t-PA can convert plasminogen to plasmin and remove the clot. From July 1999 to January 2000, ten eyes of postvitrectomy diabetic vitreous hemorrhage (PDVH) were collected. In each case, 4 days after intravitreal injection (IVI) of t-PA (30 microg), vitreous cavity lavage was performed with Chen's I/A device. Of these cases, 8 eyes (80%) experienced an immediate clearing of the vitreous cavity. Early complications included anterior hyaloid fibrovascular proliferation (2 eyes) and postoperative intraocular pressure elevation (3 eyes). On the basis of the results of this study, our conclusion is that volume homeostatic vitreous cavity lavage, combined with intravitreal injection of t-PA, is an excellent method for treatment of postvitrectomy diabetic vitreous hemorrhage but, in cases of PDVH with iris rubeosis, the advantage of this procedure is uncertain.

The expanding role of primary pars plana vitrectomy in the treatment of rhegmatogenous noncomplicated retinal detachment

The surgical management of rhegmatogenous retinal detachment has evolved dramatically during the past 2 decades. Investigators have introduced and refined alternative techniques to scleral buckling surgery including pneumatic retinopexy and primary pars plana vitrectomy (PPV). Rapid parallel developments in instrumentation, including wide-angle viewing systems, perfluorocarbon liquids, novel vitrectomy machines, intraocular tamponades, and endolaser photocoagulators have led to increasing sophistication in primary PPV surgical techniques for the treatment of rhegmatogenous uncomplicated retinal detachment. However, the precise role of primary PPV in new uncomplicated retinal detachment remains debatable owing to the lack of controlled randomized trials. This article examines primary vitrectomy treatment for rhegmatogenous uncomplicated retinal detachment and presents the specific types of retinal detachments for which primary PPV may be optimal, according to personal and reported results, the surgical instrumentation and technique, as well as the complications and limitations of this surgical method.

Sulfur hexafluoride and perfluoropropane do not escape from a plastic syringe closed with a stopcock

PURPOSE

To evaluate during various intervals of time the escape of long-acting gases contained in a plastic syringe closed with a stopcock or a plastic cap.

METHODS

A 60-ml plastic syringe was filled or partially filled with a long-acting gas, either sulfur hexafluoride or perfluoropropane. The tip of the syringe was closed with either a stopcock or the syringe's plastic cap. After various intervals of time, the concentration of the long-acting gas in the syringe was measured by gas chromatography.

RESULTS

The concentration of both long-acting gases was higher than 98% at 24 hours after filling when the syringe was closed with a stopcock; however, it was less than 41% when the syringe was filled and capped tightly with its plastic cap.

CONCLUSION

The proportion of long-acting gases escaping in 24 hours from a filled syringe capped with a stopcock is clinically insignificant.

Management of complex retinal detachment with combined relaxing retinotomy and intravitreal perfluoro-n-octane injection

We evaluated intravitreal perfluoro-n-octane injection for the positioning of large retinal flaps after relaxing retinotomies. Nineteen eyes underwent vitrectomy for advanced retinal detachments from proliferative vitreoretinopathy (11 eyes), trauma (five eyes), and proliferative diabetic retinopathy (three eyes). After retinotomy and complete relief of traction, injection of perfluoro-n-octane to a level anterior to the retinotomy edge was used to remove subretinal fluid thoroughly from beneath the retinal flap. All irrigation fluid anterior to the perfluoro-n-octane meniscus was aspirated before perfluoro-n-octane removal. Final tamponade was obtained with gas (four eyes) or silicone oil (15 eyes). After six to 17 eyes) or silicone oil (15 eyes). After six to 17 months of follow-up, the retinas were attached in 13 eyes (68%), and visual acuity of 5/200 or better was obtained in eight eyes (42%). Subretinal migration of perfluoro-n-octane and posterior slippage of the retinal flap occurred during perfluoro-n-octane/silicone oil exchange in one eye. No other complications were detected. Perfluoro-n-octane injection is an effective technique for positioning large retinal flaps after relaxing retinotomy.