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Outcomes of small-gauge vitreoretinal surgery without scleral-depressed shaving of the vitreous base in the era of wide-angle viewing systems
  1. Homayoun Tabandeh1,
  2. Nikolas J S London2,
  3. David S Boyer3,
  4. Harry W Flynn Jr4
  1. 1 Retina-Vitreous Associates Medical Group, Los Angeles, California, USA
  2. 2 Retina Consultants San Diego, Poway, California, USA
  3. 3 Retina-Vitreous Associates Medical Group, Los Angeles, California, USA
  4. 4 Ophthalmology, Bascom Palmer Eye Institute, Miami, Florida, USA
  1. Correspondence to Dr Homayoun Tabandeh, Retina-Vitreous Associates Medical Group, Los Angeles, CA 90211, USA; tabandeh100{at}gmail.com

Abstract

Purpose To evaluate outcomes of small-gauge pars plana vitrectomy (PPV) for the treatment of rhegmatogenous retinal detachment (RD) without scleral-depressed shaving of the vitreous base.

Methods Retrospective, consecutive case series. Surgical technique included small-gauge PPV (25G, 23G, 25G+ or 27G) and wide-angle vitrectomy viewing system in all cases. No cases were excluded based on the level of complexity of RD. Outcome measures were retinal reattachment rates and Snellen visual acuity (best-corrected visual activity [BCVA]).

Results 312 eyes of 301 patients, mean age 60.8 years, and mean follow-up 23.1 months. Baseline characteristics included macula-off RD in 207 (66%) eyes, psudophakia in 124 (40%) eyes, high myopia in 74 (24%) eyes and giant retinal tear in 14 (5%) eyes. The retina was reattached with one procedure in 296 (95%) eyes. Final retinal reattachment was achieved in 310 (99%) eyes. The BCVA at baseline was >20/40 in 76 (24%) eyes, 20/50–20/100 in 48 (15%) eyes, 20/200–20/400 in 46 (15%) eyes and <20/400 in 142 (46%) eyes. At the last follow-up, the BCVA was >20/40 in 168 (54%) eyes, 20/50–20/100 in 60 (19%) eyes, 20/200–20/400 in 49 (16%) eyes and <20/400 in 35 (11%) eyes. The mean change in logMAR equivalent was −0.12 for the macula-on group and −1.13 for the macula-off group (p<0.0001).

Conclusion Small-gauge PPV without scleral-depressed vitreous base shaving can be associated with good anatomical and visual outcomes. Case selection based on the complexity of RD may not be required when considering small-gauge PPV.

  • retinal detachment
  • microincision small gauge pars plana vitrectomy
  • 23 25 and 27 gauge vitrectomy
  • scleral depression
  • vitreous shave

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Introduction

Since the introduction of small-gauge pars plana vitrectomy (PPV), there have been significant improvements in instrumentations.1 Initially, small-gauge PPV was reserved for selected ‘simple’ cases such as epiretinal membrane and macular hole surgery that did not require extensive instrumentation or peripheral retinal manipulation. Flexibility of the 25G instruments made peripheral retinal work challenging. Development of 23G and 25G+ platforms minimised the surgical difficulties associated with instrument flexibility.2 There has been an expansion of the use of small-gauge PPV to include retinal detachment (RD). Many studies reporting on the use of small-gauge PPV for the management of retinal detachment excluded complex cases such as severe proliferative vitreoretinopathy (PVR), high myopia and trauma.3–9 The current study evaluated the anatomical and visual outcomes of small-gauge PPV for consecutive cases of RD without case selection based on complexity.

Scleral-depressed shaving of the vitreous base has been advocated as part of PPV for the management of primary rhegmatogenous RD (RRD).5 6 10 11 It has been postulated that the vitreous base may form a scaffold for the development of future anterior PVR, and that vitreous base contraction may cause new retinal tears and subsequent RD. The general impression has been that the outcomes are superior when scleral-depressed shaving of vitreous base is performed. However, there is little in the literature supporting this clinical impression. The perceived improved outcomes may be more a function of visualisation of the retina periphery than the actual shaving of the vitreous base. In the current series, peripheral vitreous was removed to the vicinity of the vitreous base under direct visualisation with wide-angle viewing system and no attempt was made at scleral-depressed shaving of the vitreous base.

We report on the outcomes of small-gauge PPV for RRD without case selection based on complexity and without scleral-depressed shaving of the vitreous base.

Materials and methods

Patients who underwent PPV for the management of RRD between January 2007 and September 2016 were identified by the search of the operating room records and diagnostic database. The cases included PPV surgeries performed for RRD by a single surgeon (HT) at a single surgery centre (Good Samaritan Hospital, Los Angeles, California, USA) where small-gauge PPV was available throughout the study period. There was no case selection for small-gauge PPV; all cases underwent small-gauge PPV and were included in the study. The cases included RD associated with high myopia, giant retinal tear (GRT) and failed previous RD surgeries. Preoperatively, PVR ranged from none to closed-funnel RD. Patients younger than 18 years, eyes with proliferative diabetic retinopathy, RD associated with open globe injury and cases with follow-up period less than 3 months were excluded from the study.

During the study period, the surgical technique included small-gauge PPV (25G, 23G, 25G+ and 27G) in all cases. The Advanced Visual Instruments (AVI) wide-angle viewing system (Advanced Visual Instruments, New York, New York, USA) was used for intraoperative visualisation. Scleral-depressed shaving of the vitreous base was not performed. Scleral buckle (SB) was performed at the discretion of the surgeon and was generally reserved for cases with advanced-grade PVR, persistent retinal contraction, extensive inferior pathology within a detached area and inability to comply with postoperative positioning in patients with significant inferior retinal pathology. Circumferential endolaser photocoagulation was applied routinely. In cases with advanced PVR (grade D), a surgical technique using membrane scrapers and intraocular forceps was used.12 Anterior PVR was managed using a number of surgical techniques including scleral-depressed assisted membrane removal, relaxing retinectomy and SB.

Patients’ medical records were reviewed and data were collected on demographic characteristics, ocular history, best-corrected Snellen visual acuity (BCVA), type of retina break, status of the macula, presence of PVR, type of tamponade and type of scleral buckle. Outcome measures included retinal reattachment status and BCVA.

All data were collected and entered onto a computerised database (Microsoft Excel, Microsoft Corporation, Redmond, Washington, USA). Statistical analysis was performed using SAS software V.9.4 (SAS Institute, Cary, North Carolina, USA). Descriptive statistics were first calculated to describe the characteristics of study population and summary of outcome variables. The Kruskal-Wallis test was used to compare differences in continuous variables, such as visual acuity, among subgroups. Fisher’s exact test was used to compare differences in proportions of categorical variables among subgroups, and Cochran-Armitage trend test was used to examine the trend for proportions of binary variables across ordinal categories. A p value less than 0.05 was considered as statistically significant. For the purpose of analysis, BCVA were transformed into equivalent logarithm of the minimum angle of resolution (logMAR) values.

Results

The current study included 312 eyes of 301 patients, 98 women and 203 men, with a mean age of 60.8 years (range, 19–91 years). The mean follow-up period was 23.1 months (range, 3–88 months). The BCVA at the baseline was >20/40 in 76 (24%) eyes, 20/50–20/100 in 48 (15%) eyes, 20/200–20/400 in 46 (15%) eyes and <20/400 in 142 (46%) eyes. The mean logMAR equivalent was 1.40. The retina detachment spared the macula (macula-on) in 105 (34%) eyes, and it involved the macula (macula-off) in 207 (66%) eyes. The baseline mean logMAR equivalent was 0.37 for the macula-on group and 1.93 for the macula-off group (p<0.0001). Ocular features included phakia in 184 (59%) eyes, pseudophakia in 124 (40%) eyes, aphakia in 4 (1%) eyes, high myopia (myopia greater than 6.0 dioptres) in 74 (24%) eyes and GRT in 14 (5%) eyes. PVR ranged from none to closed-funnel total RD. The baseline characteristics of the subjects are summarised in table 1.

Table 1

Baseline characteristics

The surgical technique included 27G PPV (10), 25G PPV (103) and 23G PPV (199). Adjunct scleral buckle procedure was performed in 106 (34%) eyes. Tamponading agents included sulfur hexafluoride (SF6) gas in 16 (5%) eyes, perfluoropropane (C3F8) gas in 206 (66%) eyes, silicone oil (SO) in 89 (29%) eyes and air in one eye.

The retina was reattached with one procedure in 296 (95%) eyes. Single surgery reattachment rate was 95.2% for the eyes with SB and 94.7% for the eyes without SB (p=1.0). Final retinal reattachment was achieved in 310 (99%) eyes. There was no statistically significant difference in single surgery reattachment rate between phakic (93.5%) and pseudophakic (96.8%) groups (p=0.29) or between highly myopic eyes (95.9%) and non-highly myopic eyes (94.5%) (p=0.77). The single surgery reattachment rate was 92.8% for the eyes with GRT and 94.9% for eyes without a GRT (p=0.53).

At the last follow-up, the BCVA was >20/40 in 168 (54%) eyes, 20/50–20/100 in 60 (19%) eyes, 20/200–20/400 in 49 (16%) eyes and <20/400 in 35 (11%) eyes. Two eyes had no light perception. The mean logMAR equivalent was 0.61 for the entire group.

For the 105 eyes with macula-on retinal detachment, 85 (81%) eyes had a BCVA of >20/40 at the last follow-up visit, while 2 (2%) eyes had BCVA of <20/400. At the last follow-up, the mean logMAR equivalent was 0.25, and the mean change in logMAR equivalent was −0.12 (p<0.0001).

For the 207 eyes with macula-off RD, 84 (41%) eyes achieved a BCVA of >20/40 while 34 (16%) eyes had BCVA of <20/400. At the last follow-up, the mean logMAR equivalent was 0.79, and the mean change in logMAR equivalent was −1.13 (p<0.0001). The eyes with macula-off RD had significantly more visual improvement compared with eyes with macula-on RD (mean change in logMAR equivalent −1.13 vs −0.12; p<0.0001). The anatomical and visual outcomes are summarised in table 2.

Table 2

Anatomical and visual outcomes

At the time of the last follow-up evaluation, SO was present in 13 (15%) of the 89 eyes that underwent SO tamponade at the time of their first surgery. Three eyes with failed initial surgery that subsequently underwent surgery with SO tamponade had oil present at the last follow-up visit. The reasons for not removing the SO included persistent RD in two eyes. In four eyes, the intraocular pressure was below 10 mm Hg at the last visit and SO removal was deferred in view of the risk of ocular hypotony following removal of SO. In 10 eyes, removal of SO was planned but was not performed due to a variety of reasons including deferral by the patient, relocation, change of insurance and death.

Discussion

Three-port PPV has established a major role in treatment of RRD. Recent studies have reported single surgery success rates of 74% to 98%.4–9 13–19

Introduction of 25G and 23G high-speed vitreous cutters and intraocular instruments initiated the era of small-gauge PPV.1 Advantages of small-gauge PPV include improved patient comfort, decreased conjunctival scarring, reduced postoperative inflammation, faster visual recovery and lower incidence of iatrogenic retinal breaks.20 21

Surgical indications most conducive to small-gauge PPV were initially limited to cases that did not require extensive peripheral vitrectomy or membrane dissection such as epiretinal membrane, macular hole, vitreomacular traction and vitreous opacities. Many surgeons reserved small-gauge PPV for the repair of primary non-complex RRDs, excluding cases such as those associated with proliferative vitreoretinopathy, GRT or trauma. This is reflected in the literature; most series reporting outcomes of RD repair using small-gauge PPV exclude complex cases.3–9 There are few reports on the use of small-gauge PPV for the treatment of complex RDs.22–24 In the current study, there was no case selection for small-gauge PPV and complex RDs were included. The retina was reattached with one surgery in 95% of the cases and final reattachment rate was 99%. The results are comparable with those reported for small-gauge PPV with case selection and also with those reported using 20G vitrectomy systems.4–9 13–19 25–27 Circumferential endolaser photocoagulation may be a contributing factor to the relatively high primary success rate and absence of late retinal redetachment.

There is no general consensus on the adjunctive use of SB at the time of PPV. Some reports suggest increased success rate in patients who undergo adjunct SB, while other reports suggest no significant difference in the anatomical outcome.10 13 14 16 25 27–31 In clinical practice, the surgical technique is often individualised and the choice of technique depends on a variety of factors.32 33 In the current series, 34% of eyes had SB at the time of PPV. The single-surgery success rate was similar in eyes with and without SB (95.2% and 94.7%). Care needs to be taken in comparative interpretation of these findings as eyes with SB likely had more complex RDs. Placement of a scleral buckle may counterbalance vitreous base contraction and peripheral traction in complex cases.

Routine prophylactic, scleral-depressed shaving of the vitreous base has been advocated by many as part of PPV for primary RRD.5 6 10 11 It has been postulated that the vitreous base may form a scaffold for the development of future anterior PVR, and that vitreous base contraction may cause new retinal tears and subsequent RD. There is no evidence in the literature that shaving of the vitreous base prevents or reduces the incidence of PVR. It may be argued that the shaving of the vitreous base merely brings the potential scaffold for any future PVR closer to the retina and does not eliminate the potential for contraction. Improvements in surgical success rates have resulted in fewer reoperations for RD and PVR, adding to the argument against invasive prophylactic measures. Scleral-depressed shaving of vitreous base may be associated with iatrogenic retinal breaks, cataract formation, zonular dehiscence and increased risk of intraoperative choroidal haemorrhage.34 The general impression that scleral-depressed shaving of vitreous base is associated with superior outcomes may be more a function of visualisation of the retina periphery than the actual shaving of the vitreous base. This would be particularly relevant to the early days of vitrectomy surgery prior to the era of wide-angle intraoperative visualisation. However, this clinical impression has persisted into the current practice without supporting evidence. Introduction of wide-angle viewing systems has significantly improved visualisation of peripheral retina, enabling access to the areas of clinically significant pathology. The peripheral retina may be visualised to within 2 mm of the ora serrata in most cases.35 This allows visualisation to the vicinity of the vitreous base, where the majority of clinically significant pathology is located, and makes it possible to trim the vitreous up to the base.

In summary, the current study is a large consecutive case series of RRD undergoing small-gauge PPV without scleral-depressed vitreous base shaving. There was no case selection for small-gauge PPV and the series included RDs with a range of complexity with no exclusion. The findings indicate that small-gauge PPV without scleral-depressed shaving of the vitreous base may be associated with good visual and anatomical outcomes. Phakia, pseudophakia and high myopia did not appear to influence the anatomical success rate. The study also demonstrated significant visual improvement in eyes with macula-off RD, with 41% of cases achieving a BCVA of 20/40 or better. The limitations of the study include its retrospective nature. The strengths of the study include the large size, the single-surgeon nature of the study reducing surgeon variability and the absence of bias introduced by case selection based on the complexity of the RD.

References

Footnotes

  • Contributors Case recruitment: HT, NJSL. Study design: HT, NJSL, DSB, HWFJ. Data compilation: HT, NJSL. Data analysis: HT, NJSL, DSB, HWFJ. Writing the manuscript: HT, NJSL, DSB, HWFJ.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study protocol was reviewed by the regional IRB (Quorum Review IRB) who concluded that approval was not required for this study. The study was in accordance with the principles outlined in the Declaration of Helsinki.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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