Introduction

Transconjunctival sutureless vitrectomy (TSV) techniques are reported to offer considerable potential benefits when compared with conventional pars plana vitrectomy. TSV was first described by Chen,1 the 25-gauge system by Fujii et al2 and Eckardt3 produced the 23-gauge system. These techniques have been widely adopted by the vitreoretinal community, however, as with any new technique, new surgical challenges have been encountered and a new profile of complications described. The purpose of this study was to compare the incidence and distribution of iatrogenic retinal tears in conventional sutured 20-gauge surgery with that of sutureless 23-gauge vitrectomy.

Patients and methods

One hundred consecutive patients in whom elective vitrectomy surgery was indicated for the management of epiretinal membrane (ERM), vitreomacular traction (VMT) or macular hole were included in the study. Fifty consecutive cases underwent 20-gauge vitrectomy, followed by 50 consecutive 23-gauge cases. Patients with a history of previous vitreoretinal surgery to the same eye were excluded. Data were collected by retrospective case note review.

Each patient underwent standard 3-port pars plana vitrectomy. All surgery was performed by two surgeons (JL and RN) in one center using the Alcon Accurus and Alcon 20- and 23-gauge systems (Alcon Laboratories Ltd, Hemel Hempstead, UK). All other surgical parameters were the same for both groups, including the cut rate that was controlled by the surgeon between 1500–2500 cuts/min. Where indicated clinically, combined phacovitrectomy was performed. Conventional suturing of the ports was carried out for all patients in the 20-gauge group. The 23-gauge surgery was sutureless unless an obvious leak was present at the end of the surgery. Fluid air exchange was carried out at the end of all 23-gauge procedures.

Entry-site breaks (ESB) were defined as any new vitreoretinal abnormality occurring within 1 clock hour of an entry site for which treatment with cryotherapy was deemed necessary. Other breaks not associated with an entry site were recorded; all breaks were treated with cryotherapy.

Statistical analysis was carried out using Fisher's exact test and χ2-test.

Results

Fifty consecutive 23-gauge cases and 50 consecutive 20-gauge cases were included in the study. Age distribution at the time of surgery was 57–85 years (mean 73±8.9) in the 23-gauge group, and 48–88 years (mean 70±7.2) in the 20-gauge group. There were 21 male eyes and 29 female eyes in the 23-gauge group, and 16 male and 44 female eyes in the 20-gauge group.

Twenty-six patients were pseudophakic before surgery (14/50 (28%) in the 23-gauge group, 12/50 (24%) in the 20-gauge group). Thirty-three cases were combined procedures with phacoemulsification with IOL (18/50 (36%) in the 23-gauge group, 15/50 (30%) in the 20-gauge group). A peel was performed in 86 cases (43/50 in the 23-gauge group, 43/50 in the 20-gauge group). Those not peeled were predominantly cases of VMT in addition to five cases of stage two macular hole (Table 1).

Table 1 Patient demographic data for the 20- and 23-gauge groups
Full size table

Fifty-five cases underwent macular hole repair (24/50 in the 23-gauge group, 31/50 in the 20-gauge group; P=0.85). Thirty-six cases underwent surgery for ERM (21/50 in the 23-gauge group, 15/50 in the 20-gauge group). Nine patients were specifically identified as having purely VMT pre-operatively (5/50 in the 23-gauge group, 4/50 in the 20-gauge group; Table 1).

Ten cases (4/50 in the 23-gauge group, 6/50 in the 20-gauge group) required further retinal procedures. The macular hole closure rates (with one procedure) were 96% (23/24) in the 23-gauge group, and 90% (28/31) in the 20-gauge group. This difference was not statistically significant (P=0.62). All those who failed to close were classified as stage 4 pre-operatively.

The mean gain in visual acuity for eyes was 0.23 LogMAR units in the 23-gauge group and 0.22 LogMAR units in the 20-gauge group.

ESB occurred in 8% (4/50) of the 23-gauge group as opposed to 24% (12/50) of cases in the 20-gauge group. This difference was statistically significant (P=0.029). The majority (75%) of these occurred in macular hole repairs (12/16) as opposed to ERM peels (3/16; P=0.012). In the macular hole group, 10/12 ESB were in 20-gauge cases and 2/12 were in 23-gauge cases (P=0.003). All patients undergoing macular hole repair with recorded ESB underwent an ILM peel. A single case occurred in a patient with VMT (Table 2).

Table 2 Number of entry-site breaks in the 20- and 23-gauge groups according to indication for surgery
Full size table

Eighty-eight percent of ESB (14/16) occurred superiorly on the same side as the surgeon's dominant ‘peeling’ hand.

Iatrogenic breaks recorded elsewhere occurred in 10% (5/50) of cases in the 23-gauge group as opposed to 20% (10/50) of cases in the 20-gauge group. This difference was not statistically significant (P=0.26). Four cases had more than 1 (2) breaks noted. In total 19 breaks were treated, 53% (10/19) of which were located inferiorly. The remainder were distributed temporally (4/19), superiorly (3/19), and nasally (1/19). The location of one break was unspecified. There was no significant difference in the distribution or rate of non-ESB between the 23-gauge and 20-gauge groups.

Eight-six percent (43/50) of patients in both groups underwent a peel. In the 20-gauge group, of the seven patients that were not peeled, two developed a break. Neither of these was associated with an entry site. In the 23-gauge group, there were no breaks in the seven patients that weren't peeled. There was no significant difference in the risk of developing an iatrogenic break (entry site or non-entry site) between patients who had a peel or did not have a peel (P=0.33), but the number of patients not peeled was small in both groups.

There was no significant difference in the risk of developing an iatrogenic break (entry site or non-entry site) between patients who had a single or combined procedure (P=0.07). Patients who were phakic were more likely to develop a break than pseudophakic patients (P=0.05).

One patient in the 20-gauge group developed postoperative retinal detachment requiring further vitrectomy, cryotherapy, and gas tamponade. No patients who were treated for ESB developed a retinal detachment postoperatively.

Discussion

Retinal detachment following elective vitreoretinal surgery is an uncommon but serious complication. The introduction of TSV has offered the potential of considerable benefits to patients. Initial reports identified concerns regarding complications rates associated with early sutureless vitrectomy techniques. Current evidence suggests a comparable safety profile when compared with ‘gold standard’ 20-gauge surgery.4, 5 The purpose of this study was to compare the incidence and distribution of iatrogenic retinal tears in the 20- and 23-gauge systems in patients undergoing similar elective vitreoretinal procedures.

ESB were more common in the 20-gauge group compared with the 23-gauge group (24% compared with 8%; P=0.03). To our knowledge this is the first report in the literature of a statistically significant reduction in the rate of ESB breaks associated with a 23-gauge technique.

ESB were most likely to occur on the same side as the surgeon's dominant peeling hand. Macular hole surgery was associated with an increased risk of ESB compared with surgery for ERM or VMT. This observation has been reported elsewhere in the literature.6, 7 This may result from the induction of a posterior vitreous detachment (PVD), the nature of the vitreous, and any additional instrumentation required when performing an ILM peel. The majority of patients in both the groups underwent a peel. Although we found no statistically significant difference between the rate of iatrogenic breaks (entry site or non-entry site) between patients who did, or did not, have a peel, in the small number of patients who weren't peeled no ESB were observed.

We believe there is less traction on the vitreous base during instrumentation in 23-gauge vitrectomy. The trocars extend into the eye past the vitreous base enabling instruments to pass repeatedly into the eye without engaging vitreous gel leading to less traction and fewer ESB.

Iatrogenic breaks not associated with entry sites appeared to be more common in the 20-gauge group compared with the 23-gauge group, but this difference was not statistically significant. Over half of all such breaks were located inferiorly around the 6 o'clock position. Data regarding the distribution of iatrogenic breaks in the literature is variable with some authors either reporting that breaks are most commonly located inferiorly8 or superiorly,9 whereas others have found no significant predilection for a particular location.10

The incidence of breaks did not appear to be higher in patients undergoing combined phacovitrectomy compared with vitrectomy alone, a finding supported by similar studies in the literature.11, 12

Breaks were observed more commonly in phakic compared with pseudophakic patients. This has been shown to be a factor in other studies.8 It has been observed that new breaks are more common in patients requiring surgical induction of PVD than in those with pre-existing PVD.11 This could offer an explanation for the higher rate of breaks in phakic patients compared with pseudophakic patients who might be more likely to have already developed PVD following cataract surgery.13 Our study did not compare the incidence of PVD pre-operatively in both the groups. We are therefore unable to draw any further conclusions regarding this from our data.

The overall incidence of retinal breaks quoted in the literature varies between studies. Although our rates were higher than reported figures in some similar studies,14 they are comparable with outcomes described in the literature elsewhere.8, 14 Differences in these data are due to both diagnostic criteria and surgical technique. The rate of postoperative retinal detachment was low and compares favorably with some of the larger studies reported previously.15 It is possible that this may represent a higher intraoperative detection rate. Current evidence supports our observation that the development of postoperative retinal detachment is most commonly associated with pre-existing pathology or new breaks rather than ESB.7, 16 There was no evidence of increased risk of retinal detachment in the 23-gauge group.

Overall outcomes were similar for both the 23- and 20-gauge groups. There was no significant difference in the visual outcomes between the 23- and 20-gauge groups, and no significant difference in the number of patients requiring further vitreoretinal surgery.

Conclusions

23-Gauge vitrectomy is associated with significantly fewer ESB when compared with conventional 20-gauge vitrectomy. The incidence of other iatrogenic breaks occurring away from the entry sites did not appear to be significantly different between the two groups. Iatrogenic breaks occur more commonly during macular hole surgery than during surgery for ERM or VMT. ESB, when present, were most frequently located superiorly, on the same side as the surgeon's dominant peeling hand. The incidence of postoperative retinal detachment is low and does not appear to be correlated with ESB.