Pars Plana Vitrectomy: Comparison of Three Techniques for the Treatment of Diabetic Vitreous Hemorrhage

Analgesic and Sedative Effects of Dezocine and Midazolam During Vitrectomy

PURPOSE

To evaluate the analgesic and sedative effectiveness of dezocine and midazolam in vitrectomy.

METHODS

One hundred and sixty patients undergoing vitrectomy were randomized into four groups. The control group was given local anesthetic in retrobulbar nerve block only, while the other three groups received a single dose of 0.1 mg/kg dezocine or/and 0.05 mg/kg midazolam (groups D, M, DM), respectively, at 10 min before retrobulbar block. Mean arterial pressure (MAP), heart rate (HR), and oxygen saturation (SpO₂) were recorded prior to local anesthesia (Tp), at the start of surgery (T0), 5, 15, 30 min during (T1-T3), and at the end of surgery (T4). Pain at T2 and T4 was assessed by Numeric Rating Scale (NRS). Level of sedation at T2 was assessed using the Ramsay scale. Postoperative nausea and vomiting (PONV) events were recorded for 24 h.

RESULTS

Group DM showed a decrease in HR during T0-T4 compared to Tp (p < 0.001). The MAP of all groups decreased significantly at T0 compared to Tp (p < 0.05), but remained unchanged at T1-T4. At T2, all groups have lower pain level than control (p < 0.001), while group DM showed the lowest pain level. At T4, groups D and DM showed a lower pain level than control (p < 0.01). Groups M and DM showed a higher Ramsay score than group C (p < 0.01). Compared with control, group D had a higher PONV rate (p < 0.1). Groups M and DM showed a lower PONV rate than group D (p < 0.0001), and group M had a lower PONV rate than group C (p < 0.01).

CONCLUSION

Combinatory use of dezocine and midazolam in addition to local anesthetic in retrobulbar nerve block can help relief pain and anxiety during vitrectomy and reduce PONV.

Cataract formation following vitreoretinal procedures

Purpose

To evaluate the incidence and prevalence of cataract formation, progression, and extraction in patients that underwent vitreoretinal procedures and to evaluate factors that can potentially predispose patients to postoperative cataracts.

Materials and methods

The medical records of consecutive patients who underwent vitreoretinal surgery at the Yale Eye Center with at least 6 months of follow-up and no prior intraocular surgery were obtained. Preoperative, intraoperative, and postoperative data were recorded and analyzed in this retrospective observational study. The main outcome measures were defined as cataract extraction, formation, and progression after vitreoretinal procedures. The lens status of the surgical eye was recorded preoperatively and at 1 month, 3 months, 6 months, 12 months, 24 months, and 36 months postoperatively.

Results

A total of 193 eyes of 180 patients fulfilled the inclusion criteria. The percentages of eyes with mild lens change were 96% after 20-gauge pars plana vitrectomy (PPV), 72% after small gauge (23- and 25-gauge) PPV, 38% after scleral buckle (SB), 38% after pneumatic retinopexy (PR), and 91% after PPV plus SB (PPV+SB). Posterior subcapsular and nuclear sclerotic cataracts were the most common with almost all developing within 24 months. There was no statistically significant difference (P=1.00) between the rate of cataract extraction after 20-gauge (41%) and small gauge PPV (42%), but there was a statistically significant difference between PPV and non-PPV (SB, 6%; PR, 7%; P<0.001) and PPV and PPV+SB groups (69%; P=0.0063).

Conclusion

Cataracts were common following PPV regardless of the gauge. SB and PR led to the lowest while PPV+SB led to the highest risk of postoperative cataracts.

Surface modification of vitreoretinal surgical instruments with layer-by-layer films

Commercially available vitreoretinal surgical forceps were modified with layer-by-layer (LbL) films designed to render them the ability to specifically adhere human the inner limiting membrane. Surgical forceps with two different geometries were etched, polished, and silanized before deposition of the films composed of poly (allylamine hydrochloride), poly (styrene sulfonate), and cationic gold nanoparticles. Stability and integrity of the LbL films was scrutinized by exposing the modified forceps to commercial disinfectant Cidex-OPA and then placing the instruments in a physiological-like HEPES buffer (pH 7.4, 5 mM, 154 mM NaCl). Surface topography analysis with scanning electron microscopy revealed that the geometry of the surgical instrument may affect the integrity of the film. Analysis of the HEPES buffer with inductively coupled plasma mass spectrometry demonstrated that gold nanoparticles did not leach from the LbL film after 60 min.

Advantages and limitations of small gauge vitrectomy

Small gauge vitrectomy utilizing 23- and 25-gauge instrumentation has definite advantages, but also limitations, due to the physics of smaller instruments and sutureless surgery. Higher infusion and aspiration pressures are needed to remove the vitreous using 23- and 25-gauge probes. The advantages include decreased surgical times, less tissue manipulation, reduced inflammation and pain postoperatively with more rapid visual recovery. A disadvantage is greater instrument flexion than 20-gauge probes, making small gauge vitrectomy more appropriate for indications such as vitreous opacities, epiretinal membranes, macular holes, and simple retinal detachments. There are also some increased complications related to small gauge vitrectomy, including dislocation of cannulas intraoperatively, early postoperative hypotony, choroidal detachment, and possibly an increased risk of infectious endophthalmitis.

Differences between the combination of the 25-gauge vitrectomy with phacoemulsification versus 20-gauge vitrectomy and phacofragmentation

Introduction:

In the present study we determine the differences observed between 25-gauge-vitrectomy combined with phacoemulsification, and the 20-gauge-vitrectomy combined with pars plana phacofragmentation.

Methods:

A prospective study of a sample of 987 eyes of 661 patients randomly divided into two groups. 25-gauge-vitrectomy plus phacoemulsification included 486 eyes, and 20-gauge-vitrectomy plus phacofragmentation 501 eyes. We evaluated the differences at the time of the surgery, the intra-and postoperative complications, and the variations in intraocular pressure.

Results:

The final visual outcome was similar in both groups. The most important differences between groups were: surgical time was faster in group 1 than in group 2, (mean time: 35.16 ± 3.49, 44.74 ± 5.30 minutes). Intraoperative complications were more numerous in group 1. In group 1, postoperative low levels of intraocular pressure are present in all patients with 2.77% of patients with hypotension (<8 mmHg), and three choroidal effusion. In group 2, intraocular lens decentration and retinal detachment are more frequent (2.38% and 1.39%, respectively).

Conclusions:

In the present study, both techniques have a similar number of complications and have a similar postoperative outcome, and are valid for the management of the pathologies selected.

Wound leakage and hypotony after 25-gauge sutureless vitrectomy: factors affecting postoperative intraocular pressure

BACKGROUND AND OBJECTIVE

To investigate the factors related to postoperative hypotony after 25-gauge sutureless vitrectomy.

PATIENTS AND METHODS

Of 109 consecutive eyes undergoing sutureless vitrectomy, 95 fluid-filled eyes were randomly assigned to three groups according to the order of infusion cannula removal. In group 1 (30 eyes), the infusion was removed first. In group 2 (32 eyes), the infusion was removed after another cannula. In group 3 (33 eyes), the infusion was removed last. Intraocular pressure (IOP) was measured on preoperative day 1 and postoperative days 1, 7, and 30.

RESULTS

Mean age was 58.9 +/- 11.6 years (range: 18 to 80 years). Among each factor (including order of infusion removal, age, sex, axial length, preoperative IOP, previous vitrectomy, indications for vitrectomy and lens status), only age was significantly correlated with IOP on postoperative day 1 (P = .019). In 13 eyes in which hypotony persisted through postoperative day 2 (IOP < or = 5 mm Hg), the age of the patients was significantly younger than those who did not experience persisting hypotony (P = .006).

CONCLUSION

Younger patients were more likely to experience early postoperative hypotony.

25-Gauge transconjunctival sutureless vitrectomy

PURPOSE OF REVIEW

The history and development of 25-gauge transconjunctival sutureless vitrectomy are reviewed in this paper. The expanded spectrum of appropriate cases and recent innovations in vitrectomy surgery are discussed, as are longer-term outcomes and possible complications.

RECENT FINDINGS

25-Gauge pars plana vitrectomy has evolved significantly since its introduction in 2002, with newer instruments and novel techniques expanding the scope and improving outcomes in vitreoretinal surgery. Proper case selection is imperative, as the smaller scale of the instruments and decreased fluidics work most efficiently when extensive manipulation of intraocular tissue or significant membrane dissection is not required. Unique complications of 25-gauge surgery such as hypotony and a possible increased rate of endophthalmitis may be related to unsutured sclerotomies, and revisions in surgical approach may help to decrease these potentially devastating complications.

SUMMARY

Clinical experience over the last several years has proven that this sutureless system is both safe and efficacious. Decreased surgical times, reduced postoperative inflammation, and more rapid patient recovery have all contributed to an increased acceptance of 25-gauge vitrectomy by retinal physicians.