Many advances in vitreoretinal surgical instrumentation have been made in the past several decades. Small-gauge vitreoretinal surgery with 23-gauge (G) and 25-G instruments has now largely replaced traditional 20-G vitrectomy. Oshima et al1 first reported the feasibility, efficiency, and safety of 27-G vitrectomy in a series of 31 patients, and since then, 27-G platforms have become widely available to allow the smallest-gauged techniques of modern vitreoretinal surgery.
Twenty-seven-gauge vitrectomy has several potential advantages, including the greater ability to create self-sealing sclerotomies, the reduction of postoperative inflammation and hypotony, the decrease in vitreous traction during the cutting and aspiration of vitreous, and more precise manipulation of tissues in smaller dissection planes.2–5
Smaller gauges allow for greater ability to maneuver instruments into tight spaces, which is ideal in cases such as posterior tractional detachments, and for a reduced sclerotomy size, which likely allows for better patient comfort and less need for suturing. However, there are potential challenges with 27-G surgery, such as instrument flexibility, slower fluidics, and a smaller selection of instrumentation. These factors may have limited the previous use of 27-G instruments in pediatric vitreoretinal surgeries, which tend to be more complex and high-risk in nature. Therefore, there are currently limited data regarding 27-G vitrectomy in children.
In this study, we examined 27-G vitrectomy in a series of pediatric cases to evaluate the safety, efficacy, and functional outcome of 27-G vitrectomy systems in children.
Methods
This study was a multicenter, retrospective, interventional case series of pediatric patients (aged 17 or younger) who underwent 27-G vitrectomy for a variety of diagnoses. All patients were identified via billing codes and surgical logs during the 3-year period between February 1, 2014 and August 1, 2017. Institutional review board approval was obtained from each participating center. This research adhered to the tenets of the Declaration of Helsinki and was conducted in accordance with the Health Insurance Portability and Accountability Act.
Any pediatric patient who underwent 27-G vitrectomy was eligible to be included in the study, even if the gauge had to be converted to a larger gauge intraoperatively. Surgeons used the Enhancing Visual Acuity (DORC, Zuidland, Netherlands) or the Constellation Vitrectomy System (Alcon, Geneva, Switzerland). All vitrectomies were through the pars plana/plicata. There was no follow-up requirement to be included in the study, because most of the variables were intraoperative metrics. Follow-up of at least 1 month, however, was required to be included in the visual acuity (VA) outcome measures. Data collection included age, gender, operative eye, preoperative VA, ocular and surgical history, indication for vitreoretinal surgery, intraocular pressure, surgical details, operative time, intraoperative and postoperative complications, and anatomic and VA outcomes. Hypotony was defined as an intraocular pressure of 5 mmHg or less at any postoperative visit. Operative reports were reviewed, and the following additional data were noted: number of trocar/cannulas used and sclerotomies sutured.
Visual acuity was measured with preferential looking test, Lea symbols, HOTV, or Snellen testing. Snellen and decimal VAs were converted to logarithm of the minimum angle of resolution units for statistical analyses. Paired variables were analyzed using the Wilcoxon signed-rank test. Statistical tests were two-tailed and significance was defined as P < 0.05. Stata version 9.0 (StataCorp, LP, College Station, TX) was used for statistical analyses.
Results
Fifty-six eyes of 47 patients were included in the study. Mean age at the time of vitrectomy was 5.7 ± 5.22 years (range 0–17.9 years). There were 20 female patients (43%). Surgical indications included retinopathy of prematurity (n = 12), vitreous hemorrhage (n = 8), traumatic macular hole (n = 7), ectopia lentis (n = 6), aphakia with intraocular lens placement (n = 3), persistent fetal vasculature (n = 3), posterior capsular opacity (n = 3), cataract (n = 3), epiretinal membrane (n = 3), abusive head trauma (n = 2), and congenital X-linked retinoschisis (n = 2) (Table 1). All ectopia lentis and cataract cases and one case of persistent fetal vasculature required lensectomy. There was one case each for rhegmatogenous retinal detachment, endophthalmitis, Terson's syndrome, and congenital glaucoma (vitrectomy for glaucoma tube placement).
Table 1. -
Indications and Surgical Times
| Diagnosis |
No. of Eyes (%) |
Mean Surgical Time (SD, Minutes) |
| Overall |
56 (100) |
53.0 (±29.9) |
| ROP |
12 (21.4) |
63.8 |
| Stages 3 |
3 (5.4) |
45 |
| Stage 4A |
5 (8.9) |
43.6 |
| Stage 4B |
3 (5.4) |
98.7 |
| Stage 5 |
1 (1.8) |
117 |
| Vitreous hemorrhage |
8 (14.2) |
57.5 |
| Traumatic macular hole |
7 (12.5) |
40 |
| Ectopia lentis |
6 (10.7) |
43.3 |
| Aphakia with intraocular lens placement |
3 (5.4) |
107.5 |
| Persistent fetal vasculature |
3 (5.4) |
31.3 |
| Posterior capsular opacity |
3 (5.4) |
30 |
| Epiretinal membrane |
3 (5.4) |
36.7 |
| Cataract |
3 (5.4) |
20 |
| Abusive head trauma causing vitreous hemorrhage |
2 (3.6) |
86.5 |
| Congenital X-linked retinoschisis with bullous schisis cavity overlying macula |
2 (3.6) |
50 |
| Rhegmatogenous retinal detachment |
1 (1.8) |
119 |
| Endophthalmitis |
1 (1.8) |
40 |
| Terson's syndrome |
1 (1.8) |
35 |
| Congenital glaucoma |
1 (1.8) |
20 |
ROP, retinopathy of prematurity
The instruments used were the 27-G infusion, 27-G vitreous cutter, 27-G light pipe, and 27-G internal limiting membrane forceps. The mean surgical time was 53.0 minutes with SD of 29.9 minutes (Table 1). Postoperative anatomic goals were achieved in 96.4%. Mean follow-up was 125 days (range 1–703). Mean VA improved from logarithm of the minimum angle of resolution 1.32 (20/420) to 0.72 (20/105), after a mean follow-up of 125.1 days (P = 0.01).
There were 67/145 sclerotomies (46.2%) that were sutured, of which 51/67 (76.1%) were sutured out of precaution and 16/67 (23.9%) were sutured for wound leakage and silicone oil tamponade. Instrument bending occurred in one case (1.8%). Postoperative hypotony was observed on postoperative day 1 for three cases (5.3%), but not at subsequent visits. Ten eyes required gas tamponade and six eyes required silicone oil tamponade. Surgeons elected to change one cannula into 23 G for four eyes requiring silicone oil tamponade. Two retinal detachment cases required intraoperative conversion to 23-G vitrectomy given their complexity. One was a self-inflicted trauma eye with severe tractional retinal detachment, and the other was a total retinal detachment with peripheral retinal avascularity and proliferative vitreoretinopathy. Both cases had redetached at last follow-up visit. Intraoperative complications were not observed in any of the cases. There were no cases of postoperative endophthalmitis (Table 2).
Table 2. -
Operative Profile
|
No. of Eyes (% of Cases) |
| Intraoperative |
|
| Instrument bending |
1 (1.8) |
| Infusion issues |
0 |
| Total sclerotomies made |
145 |
| Sclerotomies sutured |
67 (46.2) |
| a. Sclerotomies sutured out of precaution |
51 (35.2) |
| b. Sclerotomies sutured for leakage and silicone oil tamponade |
16 (11.0) |
| Conversion to larger gauge |
4 (7.1) |
| Postoperative |
|
| Hypotony |
3 (5.3) |
| Endophthalmitis |
0 |
Discussion
Vitrectomy is challenging in pediatric patients because of the formed vitreous without posterior vitreous detachment in most cases, complex pathologies, significantly smaller anatomic proportions of the eye and lens, and the adverse prognostic impact of iatrogenic retinal breaks. Results of 27-G vitrectomy have been reported mainly in adult eyes. To the best of our knowledge, this is the first study of this size, examining the efficacy of 27-G vitrectomy in a pediatric population. The results of this study showed that 27-G vitrectomy was safe and feasible in select pediatric vitreoretinopathies.
Only one study to date has examined 27-G vitrectomy in pediatric patients.6 This retrospective case series involved five infants with active stage 4 retinopathy of prematurity.6 All eyes achieved anatomic success. All cases were performed entirely sutureless and none had hypotony in the postoperative period compared with 5% in our study and others.7 However, the sample size was small and the ocular pathology was limited to a single indication. All of our stage 4 retinopathy of prematurity cases also achieved 100% anatomic success with 15/21 sclerotomies that were sutured and two cases that had postoperative hypotony. The most common reason for suturing of sclerotomies was surgeon preference for prophylactic suturing to minimize the risk of postoperative hypotony and vitreous hemorrhage.
Among the advantages of small-gauge surgery is the ability to create consistently self-sealing sclerotomies and thereby see a lower likelihood of postoperative hypotony. The wound diameter of a 23-G sclerotomy is approximately 0.7 mm and that of a 25-G sclerotomy is 0.5 mm. Because 27-G incisions are 0.4 mm (20% smaller than 25-G incisions), one would anticipate that they would seal better with a lower predilection for wound leakage. In 27-G cohort studies in adults, rates of postoperative hypotony were reported between 3% and 9%.2,8–10 These rates were found to be lower compared with 23-G cases.11,12 In our study, 46% (67/145) of sclerotomies required sutures with 35.2% (51/145) of these sclerotomies sutured out of precaution. The hypotony rate was 5% (four cases) on postoperative day 1 and self-limited. Sclerotomies for three of these cases were sutured at the end of surgery. One case with hypotony was a complex trauma case with serous choroidal detachment. In addition, small-gauge surgery is ideal in pediatric cases because it allows for greater maneuverability in tight spaces.
Previous studies have examined surgical times between 27-G and 25-G cases in adults. One meta-analysis of 940 eyes showed the mean operation time was significantly longer by 3 minutes for 27-G compared with 25-G vitrectomy.13 As the instrument gauge decreases, more time may be needed for vitreous dissection.14 In our study, average surgical time for pediatric cases was 53 minutes with a range of 20 minutes for cataract surgeries to 119 minutes for retinal detachments. Larger studies would be needed to further evaluate surgical times between 25-G and 27-G in pediatric cases.
Variation in rates of postoperative hypotony may be because of differences in wound structure. Six cases in our study had straight incisions whereas the rest of the cases were beveled incisions. In a pilot study comparing angled versus straight entry of the trocar insertion, Khan et al15 found that eyes with straight incisions had lower intraocular pressure on postoperative day 1 suggestive of a transient postoperative wound leak in the very early postoperative period. In vitro studies with human cadaveric eyes have suggested that 23-G angled wounds, 27-G angled wounds, and 27-G straight wounds were less likely to allow bacteria to enter the eye compared with 23-G nonbeveled sclerotomies.16 This is particularly important because in most pediatric cases, trocar insertion is not beveled and trocar entry is straight. Significant manipulation of the sclerotomies because of the movement of instruments during vitrectomy is believed to change the wound architecture. Our retrospective study did not evaluate a standardized wound architecture and further investigation in a larger cohort study would be warranted to explore whether the angled insertion of the 27-G cannula can increase the self-sealing rates and reduce the hypotony-induced complications in pediatric cases.
One of the drawbacks of 27-G vitrectomy platforms is the flexibility of the instruments, which are more prone to bend during attempts to address anterior pathology. In the current series, instrument bending was documented in only one case of vitreous hemorrhage, although this did not affect the anatomic outcome. Instrument bending occurred with anterior maneuver to remove residual vitreous hemorrhage. The predilection of 27-G tools to instrument flex requires that surgeons are cognizant of the pressure and angle between the vitreous cutter and the cannula in the sclera. Newer generation 27-G vitreous cutters and light pipes have stiffening sleeves, and newer forceps are shorter to also increase stiffness and allow for application to a wider range of surgical indications. Similar to previous 27-G studies, our eyes achieved a high level of anatomic success after vitrectomy, in 96.4% of eyes after one surgery, and had a significant improvement in mean VA from logarithm of the minimum angle of resolution 1.32 (20/420) to 0.72 (20/105). This study has several limitations inherent in its retrospective nature including risks of bias and variable follow-up time. This was a multicenter study and the surgical techniques, specific surgical instruments used, wound construction, and choice of tamponade were not standardized because these variables were determined by each surgeon based on personal preference. Visual acuity assessment is highly variable in children, and was not standardized across centers from which patients were drawn in this series. The follow-up range was broad, although many of the datapoints were ultimately to assess intraoperative feasibility. Nevertheless, prospective studies with predetermined study variables and follow-up intervals would provide superior longer-term outcome data. The study was also limited by variability in sample sizes for each indication and surgical indication criteria, and personal preferences for wound closure with sutures. The use of 27-G vitrectomy has been reported for a variety of complex vitreoretinal surgical procedures. This retrospective, multicenter case series provides support for the feasibility of 27-G vitrectomy in the pediatric population across a range of indications. Twenty-seven-gauge vitrectomy may be a useful approach for select pediatric vitreoretinopathies. Further studies are required to assess for longer-term visual and anatomic outcomes.
References
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