25-gauge vitrectomy with gas tamponade for rhegmatogenous retinal detachment: experienced vs. inexperienced surgeons

Background: To compare the results and complication rates of a 25-gauge pars plana vitrectomy (25 g PPV) with gas tamponade for rhegmatogenous retinal detachment (RRD) between experienced and inexperienced surgeons. Methods: This is a retrospective comparative consecutive case series study of patients with uncomplicated RRD treated with 25 g PPV with gas tamponade. Patients were divided into 2 groups: In Group 1 (ESG) the procedure was performed by an experienced vitreoretinal surgeon and in Group 2 (ISG) the procedure was performed by 2 inexperienced surgeons. Anatomical and functional results and complication rates were compared between the two groups. Results: 216 eyes were included in the study. In the ESG (106 eyes), the single operation success rate was 94.3%, and the nal success rate was 100%. The mean best-corrected visual acuity (BCVA) improved from 0.38 decimal to 0.73 decimal. In the ISG (110 eyes), the single operation success rate was 93.6%, and the nal success rate was 100.0%. The mean BCVA improved from 0.33 decimal to 0.74 decimal. The differences between groups were not statistically signicant. There was no difference in complication rates between groups. Conclusions: A 25 g PPV with gas tamponade for uncomplicated RRD renders excellent functional and anatomical results even when performed by an inexperienced surgeon. The complication rate was comparable between experienced and inexperienced surgeons. (25 g) PPV with gas tamponade without scleral buckling, between an experienced surgeon and two inexperienced surgeons. postoperative change in BCVA (in decimal) and complication rates. All postoperative endpoints were assessed on the last day of follow-up

94.3%, and the nal success rate was 100%. The mean best-corrected visual acuity (BCVA) improved from 0.38 decimal to 0.73 decimal. In the ISG (110 eyes), the single operation success rate was 93.6%, and the nal success rate was 100.0%. The mean BCVA improved from 0.33 decimal to 0.74 decimal. The differences between groups were not statistically signi cant. There was no difference in complication rates between groups.
Conclusions: A 25 g PPV with gas tamponade for uncomplicated RRD renders excellent functional and anatomical results even when performed by an inexperienced surgeon. The complication rate was comparable between experienced and inexperienced surgeons.

Background
Rhegmatogenous retinal detachment (RRD) is a vision-threatening condition that requires prompt surgical intervention. Several surgical techniques for the treatment of RRD have been developed with scleral buckling, pneumatic retinopexy, and pars plana vitrectomy (PPV) being currently used [1][2][3][4][5][6]. Development of sutureless, small gauge vitrectomy as well as advancements in surgical techniques and equipment have made PPV increasingly popular, among surgeons, for the management of RRD [7,8]. In our study, we compared the anatomical success rate, change in visual acuity, and complication rates in patients with RRD, performed using a 25-gauge (25 g) PPV with gas tamponade without scleral buckling, between an experienced surgeon and two inexperienced surgeons.

Patient selection
Ours was a single-center retrospective comparative consecutive case series study. Patients with RRD treated with 25 g PPV with gas tamponade without scleral buckling between October 2015 and June 2018 in the Department of Ophthalmology of the University Hospital Kralovske Vinohrady, Prague, were included in the study. Both pseudophakic and phakic patients were included. We excluded patients with proliferative vitreoretinopathy (PVR) grade C and higher, patients with a previous perforating eye injury and patients with follow-up periods shorter than 3 months. Patients were then divided into two groups. In the rst group (the experienced surgeon group [ESG]) include patients treated by an experienced surgeon (MV, 1909 PPV at the beginning and 2438 PPV at the end of the inclusion period). In the second group (the inexperienced surgeon group [ISG]) included patients treated by two inexperienced surgeons (MP and ZS, 28 and 22 PPV, respectively, at the beginning and 172 and 161 PPV, respectively, at the end of the inclusion period). Both inexperienced surgeons were trained by the same surgeon (MV) and assisted in PPV operations for 2 years prior to their rst solo vitrectomy. Both had no previous experience with intraocular surgery. We compared the anatomical success rate, change in visual acuity, and complication rate between groups. All patients signed an informed consent before the surgery. The study protocol adhered to the tenets of the Declaration of Helsinki Principles.

Pre-and postoperative assessment
In all patients, the pre-and postoperative best-corrected visual acuity (BCVA) was assessed using ETDRS charts, results of which were then converted to decimal values for statistical analysis. BCVA of counting ngers, hand motion, or light perception were converted do decimal values using the chart published by Holladay [9]. dye was used and ERM and internal limiting membrane (ILM) peeling was performed. Per uorodecalin was used in patients with a detached macula when membrane peeling was indicated. Fluid-air exchange with subretinal uid (SRF) drainage through a peripheral RB was performed using a Charles Flute Cannula (Alcon, Fort Worth, TX, USA) or a vitrectomy probe. Per uorodecalin was used or posterior retinotomies were performed to achieve complete SRF drainage in patients where the surgeon was concerned about the risk of a retinal fold forming in the macula. Posterior retinotomies were also performed in patients where pre-existing RB were not identi ed during vitrectomy. Per uorodecalin was used and retinotomies were performed at the discretion of the surgeon. Complete SRF drainage was not required. Retinopexy of the margins of RB, lattice degenerations and other suspicious peripheral lesions were performed under air using an endolaser or cryotherapy probe. In some patients, retinopexy to the extent of the detached retina or a 360° retinopexy was performed. The extent of retinopexy depended on the number and location of RB and the lattice degenerations and was also at the discretion of the

Results
Study inclusion criteria were met by 216 eyes of 216 patients. Table 1 shows the baseline demographic and clinical characteristics of the participants. One patient in the ESG underwent unsuccessful pneumatic retinopexy with laser barrage around the RB prior to the PPV, one patient had undergone scleral buckling for retinal detachment 11 years prior to the PPV. In the ISG two patients underwent unsuccessful laser retinopexy around the RB prior to the PPV. A macular hole was present preoperatively in 2 patients in the ESG. ILM peeling was performed during PPV for retinal detachment in both patients, the macular hole closed in one of them. Table 2 shows the surgical techniques and gas tamponade used in both groups. Visual acuity improved from 0.38 decimal in the ESG and 0.33 decimal in the ISG to 0.73 decimal and 0.74 decimal, respectively. The difference was not statistically signi cant (P = 0.234).
The complication rate was similar between both groups. The most common complication was postoperative intraocular hypertension in 34 (32.1%) patients in the ESG and 38 (34.5%) patients in the ISG. Three patients in each group required temporary therapy with oral acetazolamide, and one patient in the ESG underwent laser iridotomy. All other cases were resolved with IOP-lowering topical medication. Intraocular hypotony occurred in one patient in each group and resolved without therapy. Two patients in the ESG and ve patients in the ISG underwent further PPV for ERM formation in the macula. A postoperative macular hole occurred in two patients in the ESG and one patient in the ISG. Other complications occurred once in other patients from both groups. These included an iatrogenic posterior lens capsule tear, postoperative intraocular hemorrhage, and subretinal per uorocarbon. Cataract surgery was needed during the follow-up period in 66.7% of phakic patients in the ESG and 80.0% of phakic patients in the ISG. This difference was not statistically signi cant (P = 0.07)

Discussion
In our study, inexperienced surgeons were able to match the success rate of an experienced surgeon in uncomplicated RRD from the very start, suggesting a short learning curve. Although there was a statistically signi cant age difference between the two study groups, we do not believe it in uenced the results since the anatomical and functional characteristics of retinal detachment were similar in both groups. Single operation success rates in both groups were comparable to previously published gures for 25 g PPV with gas tamponade [10][11][12][13]. We believe this is due to the simpli ed operation technique used in our clinic. We try to limit the use of surgical techniques that have not been shown to improve uncomplicated RRD surgery outcomes. These include the use of per uorodecalin [14,15], complete subretinal uid drainage [10,16,17], and 360° retinopexy [18]. Limiting the use of these techniques may also prevent certain postoperative complications [19][20][21][22].
Surgical techniques employed by the experienced and surgeons in our study were similar, exceptions being the selection of intraocular tamponade and frequency of sclerotomy suturing. The inexperienced surgeons used C3F8 gas more often, which is longer lasting and the more "secure" option. We believe this was due to inexperience a subsequent lack of self-con dence which led inexperienced surgeons to use C3F8 gas even in the cases where it might not have been necessary. In our opinion, the more frequent use of C3F8 in ISG was also the reason for higher cataract surgery rate after the PPV between the ESG and ISG, although the difference was not statistically signi cant. The higher rate of sclerotomy suturing could possibly be explained by the longer operating times in the ISG; however, we do not have data to support this claim as the duration of the operation was not recorded.
The complication rate was very similar in both study groups. There was a notable difference in cataract surgery rate after the PPV between the ESG and ISG, although the difference was not statistically signi cant The low postoperative intraocular hypotony rate can be explained by the oblique cannula insertion technique used by all surgeons [23,24] and the use of digital palpation to assess IOP after the removal of cannulas.
Other studies have shown comparable results in PPV for RRD between experienced and inexperienced surgeons [25][26][27][28][29][30]. Ehrlich et al. and Dugas et al. [25,26] compared the success rates of sutureless PPV for RRD between experienced and inexperienced surgeons and used similar exclusion and inclusion criteria as our study. In both these studies, the combined single operation success rate for both studies was 75% (80.9% and 75.4%, respectively, for experienced surgeons and 70.0% and 74.8%, respectively, for inexperienced surgeons), which was signi cantly lower than in our study. This can be explained by the improvements in surgical instruments and vitrectomy machines as well as in surgical techniques. For example, the high-speed vitrectomy has been shown to lower the number of iatrogenic retinal tears during PPV [31]. It should also be noted that in a study by Ehrlich et al., the less experienced vitrectomy surgeons were recruited from fellows who had extensive experience in other intraocular procedures whereas in our study, both inexperienced surgeons had no previous experience with intraocular surgery.

Conclusions
The 25 g PPV with gas tamponade for treatment of RRD yields excellent anatomical results and improvement in BCVA. The single operation success rate was high even when performed by inexperienced surgeons, suggesting a short learning curve. The complication rate was comparable between experienced and inexperienced surgeons.