Face‐down positioning or posturing after vitrectomy for macula‐involving rhegmatogenous retinal detachments

Objectives

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

The primary objective of this review is to determine whether face‐down positioning reduces the risk of retinal displacement following pars plana vitrectomy (PPV) and gas tamponade for macula‐involving rhegmatogenous retinal detachment (RRD).

Background

Description of the condition

The term rhegmatogenous retinal detachment (RRD) refers to separation of the neurosensory retina from the retinal pigment epithelium caused by one or more full‐thickness retinal breaks (Sodhi 2008). Retinal breaks originate from vitreoretinal traction and allow fluid from the vitreous cavity to enter the subretinal space (Ghazi 2002). RRD is one of the most common ophthalmic surgical emergencies (Grey 1989), and usually requires surgical intervention. Worldwide, the reported annual incidence of RRD varies. It was reported to be 14 cases per 100,000 persons per year in Sweden (Algvere 1999); 12.05 cases per 100,000 persons per year in Scotland (Mitry 2010); and 7.98 cases per 100,000 persons per year in Beijing (Li 2003). RRD is more common in men than women (Limeira‐Soares 2007; Mitry 2010; Mowatt 2003), and has the highest incidence rate in people aged 60 to 70 years (Mitry 2010). Major predisposing factors for the development of an RRD include high myopia (Clayman 1981; Ninn‐Pedersen 1996), ocular trauma (Cox 1969; Nagpal 2004), cataract surgery (Lois 2003), ocular infections (Davis 1999; Doft 2000), and lattice degeneration (Ashrafzadeh 1973; Benson 1978). RRD is often preceded by symptoms of light flashes, floaters, or a progressive shadow over the field of vision (Gariano 2004). RRD is diagnosed based on dilated fundus examination. Late presentation in RRD may cause significant visual morbidity from macula involvement. Advanced age is associated with late presentation (Siddiqui 2010). Late presentation may also occur as a result of lack of awareness of the condition or its presenting symptoms (Goezinne 2009; Quintyn 2006). In the Scottish Retinal Detachment epidemiology study of 1202 RRD cases, the macula was affected in more than 50% of cases at presentation (Mitry 2011). Pars plana vitrectomy (PPV) with gas tamponade is a common procedure used to repair macula‐involving RRD with a high rate of anatomic retinal reattachment (Jackson 2014). A critical component of the surgical procedure is to identify all retinal breaks and treat them with either cryotherapy or laser therapy to create a thermal adhesion. The gas tamponade is used to approach the neurosensory retina to the retina pigment epithelium (RPE) and to reduce or eliminate the rate of fluid going through the open retinal break(s) until the adhesion around the break occurs, creating a permanent seal. Following surgery, most surgeons advise patients to maintain their heads in a particular head posture; this will depend on the characteristics of the retinal detachment, location of retinal breaks and, to a certain extent, surgeon's preference. Despite successful retinal reattachment, several studies have shown that 44% to 72% of eyes in patients with macula‐involving RRD had unintentional retinal displacement postoperatively (Brosh 2020; Casswell 2020; Lee 2013; Pandya 2012; Shiragami 2010; Shiragami 2015). It has been hypothesized that stretching of the retina from displacement of subretinal fluid induced by the buoyant force of a gas tamponade leads to retinal displacement (Figure 1) (Brosh 2020; Mason 2022). However, the mechanism for its occurrence remains to be fully elucidated. Retinal displacement can cause metamorphopsia (dell’Omo 2013; Pandya 2012; Shiragami 2015), and lower vision‐related quality of life (Lina 2016).

1.

Figure 1. Proposed mechanism of retinal displacement. Subretinal fluid (blue areas) typically remains at the macula in the immediate postoperative period following PPV and gas tamponade for a macula‐involving RRD. Retinal displacement may occur as a result of subretinal fluid flow under the retina induced by the buoyant force of the gas bubble and gravity in a direction related to postoperative head positioning, leading to stretching of the retina as demonstrated by the stretch of the retinal vessels.

Description of the intervention

PPV, identification and treatment of the retinal break(s), and injection of gas are performed to repair macula‐involving RRDs. In some cases, removal of either the natural crystalline lens or an artificial lens may be performed, as required. After completion of the surgery, face‐down positioning for a variable period, as much as 10 days, has been advocated to reduce the risk of retinal displacement (Casswell 2020; dell’Omo 2013; Schawkat 2019; Shiragami 2015).

How the intervention might work

Face‐down positioning after PPV and gas tamponade for a macula‐involving RRD is believed to reduce the risk of any residual subretinal fluid that remains at the end of surgery from displacing the retina inferiorly under the influence of gravity (Figure 2) (Brosh 2020; Codenotti 2013; Mason 2022; Pandya 2012; Shiragami 2015).

2.

Figure 2. Proposed mechanism of face‐down positioning for preventing retinal displacement. By positioning face‐down after PPV and gas tamponade without an intervening elevated head position, any subretinal fluid that remains at the macula in the immediate postoperative period will be encouraged to flow in all directions rather than just inferior, leading to lower rates of inferior retinal displacement.

Why it is important to do this review

Several studies have been conducted to assess the role of face‐down positioning following PPV and gas tamponade on retinal displacement for macula‐involving RRD (Casswell 2020; dell’Omo 2013; Schawkat 2019; Shiragami 2015). However, there is no consensus as to whether face‐down positioning following PPV and gas tamponade is sufficiently effective at reducing retinal displacement in order to improve the care and outcomes of people with macula‐involving RRDs.

Although no guidelines exist concerning the duration of face‐down positioning, vitreoretinal surgeons (VR) typically advocate strict face‐down positioning for a minimum of 50 minutes of every hour and throughout the night for one to two weeks after PPV and gas tamponade (Casswell 2020; Seno 2015; Shiragami 2015). Face‐down positioning is a challenge for many patients. Elderly people and those with cervical spondylosis, obesity, or coronary heart disease have serious difficulties adhering to the face‐down position (Chen 2015). Face‐down positioning may cause people to complain of musculoskeletal pains; and they may suffer mental stress, anxiety, and a sense of psychological isolation (Harker 1996). Face‐down positioning after PPV and gas tamponade also bears the risk of pressure sores (Treister 1996), and ulnar nerve palsies (Brouzas 2011; Ciulla 1996).

In order to evaluate the beneficial and adverse effects of face‐down positioning on retinal displacement after PPV and gas tamponade for macula‐involving RRDs, we will seek to undertake a Cochrane Review. Findings of our review will be important to inform vitreoretinal surgeons and patients of the potential benefits of face‐down positioning following PPV and gas tamponade for the repair of macula‐involving RRDs.

Objectives

The primary objective of this review is to determine whether face‐down positioning reduces the risk of retinal displacement following pars plana vitrectomy (PPV) and gas tamponade for macula‐involving rhegmatogenous retinal detachment (RRD).

Methods

Criteria for considering studies for this review

Types of studies

We will include randomized controlled trials (RCTs) that have investigated the effect of face‐down positioning on retinal displacement following PPV and gas tamponade for the repair of macula‐involving RRDs. RCTs will be eligible for inclusion in the review irrespective of the extent of retinal detachment, location of retinal breaks, or type of gas tamponade used.

Types of participants

We will include adult participants with macula‐involving RRDs undergoing primary PPV and gas tamponade. We will employ no restrictions with respect to extent of RD, location of retinal breaks, or type of gas tamponade used.

Types of interventions

The intervention under investigation is face‐down positioning after PPV and gas tamponade for macula‐involving RRDs. In this review, we will include studies comparing face‐down positioning against no positioning or against another form of positioning.

Types of outcome measures

We plan to assess the following outcome measures.

Primary outcomes

Critical outcome

1. Proportion of eyes with retinal displacement at six months or later following primary PPV and gas tamponade for a macula‐involving RRD. For studies that reported outcomes at multiple eligible time points, we will collect outcome data reported at the longest follow‐up period (for all outcomes).

Secondary outcomes

Important outcomes

1. Proportion of eyes with retinal displacement within three months following primary PPV and gas tamponade for a macula‐involving RRD.

2. Mean change in logarithm of the Minimum Angle of Resolution (logMAR) or Snellen visual acuity from baseline to three months or later following primary PPV and gas tamponade.

3. Mean objective distortion score (e.g. D chart test score, McGowan 2016) at three months or later following primary PPV and gas tamponade.

4. Quality of life assessments (e.g. the National Eye Institute Visual Function Questionnaire (NEI VFQ, Potic 2021)) at three months or later following primary PPV and gas tamponade.

5. Frequency of intervention‐related ocular adverse events, recorded following the Complications of Retinal Detachment Surgery (CORDS) Classification (Xu 2021), including:

   1. outer retinal folds;

   2. binocular diplopia;

   3. elevated intraocular pressure.

6. Frequency of intervention‐related non‐ocular adverse events, if provided in published RCTs, including:

   1. pressure sores;

   2. ulnar nerve palsies;

   3. anxiety disorder.

We will report each ocular and non‐ocular adverse event as the proportion of participants who experienced the specific adverse event, and grade it.

Search methods for identification of studies

Electronic searches

The Cochrane Eyes and Vision Information Specialist will search the following electronic databases for randomized controlled trials and controlled clinical trials. There will be no restrictions to language or date of publication.

• Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) in the Cochrane Library (latest issue) (Appendix 1).

• MEDLINE Ovid (1946 to present) (Appendix 2).

• Embase.com (1947 to present) (Appendix 3).

• PubMed (1948 to present) (Appendix 4).

• LILACS (Latin American and Caribbean Health Science Information database (1982 to present) (Appendix 5).

• US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.ClinicalTrials.gov) (Appendix 6).

• World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp) (Appendix 7).

Searching other resources

We will search the reference lists of the studies included in the review for other potential inclusions. We will not search conference proceedings for the purpose of this review. We will seek to obtain information about ongoing studies by contacting the relevant trial investigators.

Data collection and analysis

Selection of studies

After the information specialist performs the database searches, two authors will independently assess the titles and abstracts of all records identified and imported into the web‐based citation management software Covidence. We will label each citation as 'No (not relevant)', 'Maybe (relevant)' or 'Yes (relevant)'. We will retrieve full‐text reports for records labeled as 'Yes' or 'Maybe'. Two review authors will independently review the full‐text manuscripts according to the eligibility criteria for this review and classify them as 'exclude' or 'include'. We will resolve any discrepancies between the two authors with regard to the above classification by discussion or in consultation with a third review author.

Data extraction and management

Two authors will extract data independently using a data extraction form developed by Cochrane Eye and Vision US Project in Covidence. For each included RCT we will extract the following information, if provided by the RCT.

• Study methods (single center or multicenter, method of allocation, masking (blinding), exclusions after randomization, losses to follow‐up and compliance)

• Study participants (country(ies) where participants were enrolled, number randomized, age, gender, ethnicity, inclusion and exclusion criteria).

• Surgeon details (number of surgeons, grade of surgeons).

• Surgical details (preoperative visual acuity, eye laterality, lens status, location and quadrants of retina detached, number and location of retinal breaks, presence or absence of proliferative vitreoretinopathy, performance of 360 degree laser barrier, use of intraoperative surgical adjuncts such as perfluorocarbon liquid, complete or partial fluid‐gas exchange, type of gas tamponade used (air, SF₆, C₂F₆, C₃F₈))

• Study interventions (test and comparison (control) intervention, duration of intervention, timing of intervention).

• Outcomes following surgery (presence or absence of retinal displacement, quantification of retinal displacement, visual acuity, distortion score, quality of life score, adverse events following the intervention), and how they were measured.

• Source(s) of funding and potential conflicts of interest.

• Details and contact information of the corresponding author.

We will contact trial investigators where appropriate to clarify any information. Review authors will resolve any discrepancies in extracted data by discussion. One review author will enter data into RevMan Web 2022, and a second author will verify data entries.

Assessment of risk of bias in included studies

Two authors will independently judge the risk of bias in included studies, using the Risk of Bias 2 (RoB 2) tool outlined in Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2022). This tool incorporates assessment of bias arising from the randomization process (random sequence generation and allocation concealment), bias due to deviations from intended interventions (masking of participants and treatment providers), bias due to missing outcome data (incomplete outcome data), bias in measurement of the outcome (blinding of outcome assessment) and bias in selection of the reported result. We will apply the RoB2 tool to the critical outcome (proportion of eyes with retinal displacement) and two important outcomes (quality of life assessments and objective distortion scores).

We will contact trial investigators where appropriate for clarification of trial information or results. In the event of failure to communicate with the trial investigators or failure to obtain responses within a reasonable time‐period, we will assess the risk of bias based on the available information. We will resolve disagreements through discussion.

Measures of treatment effect

We will calculate the risk ratios (RR) with 95% confidence intervals (CI) for comparison of dichotomous outcomes, including proportion of eyes with retinal displacement; proportion of each specified ocular adverse event. We will calculate the mean differences (MDs) or standardized mean differences (SMDs) depending on the types of measurement scales used for comparison of continuous outcomes, such as visual acuity in logMAR or Snellen lines (or letters); distortion scores (Li 2022).

Unit of analysis issues

The unit of analysis for outcomes will be eyes of individuals. Whenever both eyes of all or some individuals were included in an RCT, we will include data from such a design only when the investigators appropriately considered intraperson correlation in the analyses.

Dealing with missing data

Lack of information about the characteristics of any data will raise concerns regarding whether the missing data may have introduced bias. Where statistical data are missing or unclear, we will contact the primary trial investigators for clarification and further information. If we receive no responses within two weeks, we will proceed with complete‐case analysis, assuming that data were missing‐at‐random (Bhaskaran 2014); we will evaluate the assumption by collecting data on the numbers of participants (or eyes) excluded or lost to follow‐up after randomization and the reasons, when available.

Assessment of heterogeneity

We will evaluate the overall characteristics of included studies, especially characteristics of study participants, types of interventions, and study design, to assess the extent of clinical and methodological heterogeneity before conducting meta‐analysis. We will assess statistical heterogeneity by inspecting the distribution of effect size estimates presented in the forest plots and using the I² statistic to assess the proportion of total variability explained by heterogeneity among studies. As suggested in Chapter 10 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2022), we will use the following thresholds for interpreting I² values:

• 0% to 40%: may not be important;

• 30% to 60%: may represent moderate heterogeneity;

• 50% to 90%: may represent substantial heterogeneity;

• 75% to 100%: considerable heterogeneity.

Assessment of reporting biases

We will assess selective result reporting of the selected review outcomes by the associated signaling questions of the RoB2 tool (Higgins 2022). When there are 10 or more eligible trials, we will use funnel plots to assess the presence of small‐study effects and explore potential reasons that may contribute to asymmetry of the funnel plots, such as publication bias, in reported studies as guided by Chapter 13 of the Cochrane Handbook for Systematic Reviews of Interventions (Page 2022).

Data synthesis

For all included trials we will provide qualitative synthesis for each review outcome specified. We will perform quantitative data synthesis according to the guidelines set out in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (McKenzie 2022a). We will use fixed‐effects models if there are two trials reporting on the same outcome and use random‐effects models if there are more than two trials providing data for a given outcome. When the direction of treatment effects is inconsistent across trials, or we note evidence of substantial or considerable statistical heterogeneity, we will not combine trial results in a meta‐analysis but present a narrative synthesis of results instead according to the guidance in Chapter 12 of the Cochrane Handbook (McKenzie 2022b).

Subgroup analysis and investigation of heterogeneity

We do not intend to perform subgroup analysis.

Sensitivity analysis

For analyses relevant to the critical outcome, we plan to conduct a sensitivity analysis to determine the impact of exclusion of studies at overall high risk of bias and industry‐funded studies, if sufficient data are available .

Summary of findings and assessment of the certainty of the evidence

We will prepare a summary of findings table for the following outcomes, which will include the assumed absolute risks based on the relative risks estimated across the included studies.

• Proportion of eyes with retinal displacement at six months or later following primary PPV and gas tamponade for a macula‐involving RRD.

• Mean change in logMAR or Snellen visual acuity from baseline to three months or later following primary PPV and gas tamponade.

• Mean objective distortion score at three months or later following primary PPV and gas tamponade.

• Quality of life assessments at three months or later following primary PPV and gas tamponade.

• Frequency of intervention‐related ocular adverse events, recorded following the Complications of Retinal Detachment Surgery (CORDS) Classification.

• Frequency of intervention‐related non‐ocular adverse events.

Two review authors will independently rate the certainty of the evidence for each outcome using the GRADE classification (Schünemann 2022) and judge the certainty of evidence as 'very low', 'low', 'moderate', or 'high'. We will resolve any disagreements by discussion or consultation with a third review author.

Appendices

Appendix 1. CENTRAL search strategy

#1 MeSH descriptor: [Retinal Detachment] explode all trees
#2 MeSH descriptor: [Retinal Perforations] explode all trees
#3 MeSH descriptor: [Vitreous Detachment] explode all trees
#4 rhegmatogenous OR RRD
#5 (retina*) NEAR/3 (break* OR tear* OR hole* OR detach* OR perforat*)
#6 (macula* NEXT/1 (off OR on OR involv*))
#7 {OR #1‐#6}
#8 MeSH descriptor: [Vitrectomy] explode all trees
#9 Vitrectom* OR PPV
#10 {OR #8‐#9}
#11 MeSH descriptor: [Postoperative Care] explode all trees
#12 MeSH descriptor: [Postoperative Period] explode all trees
#13 MeSH descriptor: [Postoperative Complications] explode all trees
#14 MeSH descriptor: [Patient Positioning] explode all trees
#15 MeSH descriptor: [Posture] explode all trees
#16 (postur* OR position* OR prone OR supine)
#17 "face down" OR "facing down" OR "faced down"
#18 postoperativ* OR "post operative" OR postsurgical* OR "post surgical" OR "post surgery"
#19 (retina* NEAR/3 displace*)
#20 shift* OR stretch* OR slippage* OR folds
#21 {OR #11‐#20}
#22 #7 AND #10 AND #21 in Trials

Appendix 2. MEDLINE (Ovid) search strategy

1. Randomized Controlled Trial.pt.
2. Controlled Clinical Trial.pt.
3. (randomized or randomised).ab,ti.
4. placebo.ab,ti.
5. drug therapy.fs.
6. randomly.ab,ti.
7. trial.ab,ti.
8. groups.ab,ti.
9. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8
10. exp animals/ not humans.sh.
11. 9 not 10
12. exp Retinal Detachment/
13. exp Retinal Perforations/
14. exp Vitreous Detachment/
15. (rhegmatogenous or RRD).tw.
16. (retina* adj3 (break* or tear* or hole* or detach* or perforat*)).tw.
17. (macula* adj1 (off OR on OR involv*)).tw.
18. or/12‐17
19. exp Vitrectomy/
20. (Vitrectom* or PPV).tw.
21. 19 or 20
22. exp Postoperative Care/
23. exp Postoperative Period/
24. exp Postoperative Complications/
25. exp Patient Positioning/
26. exp Posture/
27. (postoperative* or "post operative*" or postsurgical* or "post surgi*" or "post surger*").tw.
28. (postur* or position* or prone or supine).tw.
29. ("face down" or "facing down" or "faced down").tw.
30. (retina* adj3 displace*).tw.
31. (shift* or stretch* or slippage* or folds).tw.
32. or/22‐31
33. 18 and 21 and 32
34. 11 and 33

The search filter for trials at the beginning of the MEDLINE strategy is from the published paper by Glanville 2006.

Appendix 3. EMBASE.com search strategy

#1 'randomized controlled trial'/exp
#2 'randomization'/exp
#3 'double blind procedure'/exp
#4 'single blind procedure'/exp
#5 random*:ab,ti
#6 #1 OR #2 OR #3 OR #4 OR #5
#7 'animal'/exp OR 'animal experiment'/exp
#8 'human'/exp
#9 #7 AND #8
#10 #7 NOT #9
#11 #6 NOT #10
#12 'clinical trial'/exp
#13 (clin* NEAR/3 trial*):ab,ti
#14 ((singl* OR doubl* OR trebl* OR tripl*) NEAR/3 (blind* OR mask*)):ab,ti
#15 'placebo'/exp
#16 placebo*:ab,ti
#17 random*:ab,ti
#18 'experimental design'/exp
#19 'crossover procedure'/exp
#20 'control group'/exp
#21 'latin square design'/exp
#22 #12 OR #13 OR #14 OR #15 OR #16 OR #17 OR #18 OR #19 OR #20 OR #21
#23 #22 NOT #10
#24 #23 NOT #11
#25 'comparative study'/exp
#26 'evaluation'/exp
#27 'prospective study'/exp
#28 control*:ab,ti OR prospectiv*:ab,ti OR volunteer*:ab,ti
#29 #25 OR #26 OR #27 OR #28
#30 #29 NOT #10
#31 #30 NOT (#11 OR #23)
#32 #11 OR #24 OR #31
#33 'retina detachment'/exp
#34 'retina tear'/exp
#35 'vitreous body detachment'/exp
#36 'retinal detachment surgery'/exp
#37 'retinal detachment complications'/exp
#38 rhegmatogenous:ab,ti,kw OR RRD:ab,ti,kw
#39 (retina* NEAR/3 (break* OR tear* OR hole* OR detach* OR perforat*)):ab,ti,kw
#40 (macula* NEXT/1 (off OR on OR involv*)):ab,ti,kw
#41 #33 OR #34 OR #35 OR #36 OR #37 OR #38 OR #39 OR #40
#42 'vitrectomy'/exp
#43 vitrectom*:ab,ti,kw OR ppv:ab,ti,kw
#44 #42 OR #43
#45 'postoperative care'/exp
#46 'postoperative period'/exp
#47 'postoperative complication'/exp
#48 'patient positioning'/exp
#49 'body position'/exp
#50 'prone positioning'/exp
#51 'prone position'/exp
#52 'face down positioning'/exp
#53 postur*:ab,ti,kw OR position*:ab,ti,kw OR prone:ab,ti,kw OR supine:ti,ab,kw
#54 'face down':ab,ti,kw OR 'facing down':ab,ti,kw OR 'faced down':ab,ti,kw
#55 postoperative*:ab,ti,kw OR 'post operative*':ab,ti,kw OR postsurgical*:ab,ti,kw OR 'post surgi*':ab,ti,kw OR 'post surger*':ab,ti,kw
#56 (retina* NEAR/3 displace*):ab,ti,kw
#57 shift*:ab,ti,kw OR stretch*:ab,ti,kw OR slippage*:ab,ti,kw OR folds:ab,ti,kw
#58 #45 OR #46 OR #47 OR #48 OR #49 OR #50 OR #51 OR #52 OR #53 OR #54 OR #55 OR #56 OR #57
#59 #41 AND #44 AND #58
#60 #32 AND #59

The search filter for trials at the beginning of the Embase strategy is adapted from the published paper by Lefebvre 2008.

Appendix 4. PubMed search strategy

#1 ((randomized controlled trial[pt]) OR (controlled clinical trial[pt]) OR (randomised[tiab] OR randomized[tiab]) OR (placebo[tiab]) OR (drug therapy[sh]) OR (randomly[tiab]) OR (trial[tiab]) OR (groups[tiab])) NOT (animals[mh] NOT humans[mh])
#2 Rhegmatogenous[tw] OR RRD[tw]
#3 (retina*[tw] AND (break*[tw] OR tear*[tw] OR hole*[tw] OR detach*[tw] OR perforat*[tw]))
#4 ("macula off"[tw] OR "macular off"[tw] OR "macula on"[tw] OR "macular on"[tw] OR "macula involv*"[tw] OR "macular involv*"[tw])
#5 #2 OR #3 OR #4
#6 (Vitrectom*[tw] OR PPV[tw])
#7 (postoperative*[tw] OR "post operative*"[tw] OR postsurgical*[tw] OR "post surgi*"[tw] OR "post surger*"[tw])
#8 (postur*[tw] OR position*[tw] OR prone[tw] OR supine[tw])
#9 ("face down"[tw] OR "facing down"[tw] OR "faced down"[tw])
#10 (retina*[tw] AND displace*[tw])
#11 shift*[tw] OR stretch*[tw] OR slippage*[tw] OR folds[tw]
#12 #7 OR #8 OR #9 OR #10 OR #11
#13 #5 AND #6 AND #12
#14 #1 AND #13
#15 Medline[sb]
#16 #14 NOT #15

Appendix 5. LILACS search strategy

(MH:C11.768.648$ OR MH:C11.768.740$ OR MH:C11.980$ OR Rhegmatogenous OR (retina$ AND (break$ OR tear$ OR hole$ OR detach$ OR perforat$)) OR "macula off" OR "macular off" OR "macula on" OR "macular on" OR "macula involving" OR "macular involving") AND (MH:E04.540.960$ OR Vitrectom$ OR PPV) AND (MH:E02.760.731.700$ OR MH:E04.604.500$ OR MH:N02.421.585.722.700$ OR MH:E04.614.750$ OR MH:N02.421.585.753.750$ OR MH:C23.550.767 OR MH:E02.760.670$ OR MH:N02.421.585.700$ OR MH:G11.427.695$ OR postoperative$ OR "post operative" OR postsurgical$ OR "post surgical" OR "post surgery" OR postur$ OR position$ OR prone OR supine OR "face down" OR "facing down" OR "faced down" OR (retina$ AND displace$) OR shift$ OR stretch$ OR slippage$ OR folds)

Appendix 6. ClinicalTrials.gov search strategy

(rhegmatogenous OR retinal break OR retinal tear OR retinal hole OR retinal detachment OR retinal perforation OR "macula off" OR "macular off" OR "macula on" OR "macular on" OR "macular involving") AND (Vitrectomy OR PPV) AND (posture OR position OR positioning OR prone OR supine OR "face down" OR "facing down" OR "faced down" OR postoperative OR "post operative" OR postsurgical OR "post surgical" OR "post surgery" OR displace OR displacement OR shift OR shifting OR stretch OR slippage OR folds)

Appendix 7. ICTRP search strategy

rhegmatogenous AND vitrectomy OR rhegmatogenous AND PPV OR retinal detachment AND vitrectomy OR retinal detachment AND PPV OR retinal break AND vitrectomy OR retinal break AND PPV OR retinal tear AND vitrectomy OR retinal tear AND PPV OR retinal hole AND vitrectomy OR retinal hole AND PPV OR retinal perforation AND vitrectomy OR retinal perforation AND PPV OR macula off AND vitrectomy OR macula off AND PPV OR macular off AND vitrectomy OR macular off AND PPV OR macula on AND vitrectomy OR macula on AND PPV OR macular on AND vitrectomy OR macular on AND PPV OR macula involving AND vitrectomy OR macula involving AND PPV OR macular involving AND vitrectomy OR macular involving AND PPV

Contributions of authors

All authors contributed clinical expertise and advice to formulating the review question, study selection, data extraction and assessment, risk of bias assessment, conception and writing of the protocol.

Sources of support

Internal sources

• None, Other

  No internal source of support

External sources

• National Eye Institute, National Institutes of Health, USA

  Cochrane Eyes and Vision US Project, supported by grant UG1EY020522 (PI: Tianjing Li, MD, MHS, PhD)

• Public Health Agency, UK

  The HSC Research and Development (R&D) Division of the Public Health Agency funds the Cochrane Eyes and Vision editorial base at Queen's University Belfast.

• Queen’s University Belfast, UK

  The work of Gianni Virgili, Co‐ordinating Editor for Cochrane Eyes and Vision, is funded by the Centre for Public Health, Queen’s University of Belfast, Northern Ireland.

Declarations of interest

TF: no relevant interests.
NL: no relevant interests.
DW: no relevant interests.
SL: reports a grant UG1 EY020522 from the National Eye Institute, National Institutes of Health, USA; payment to institution.
TW: no relevant interests

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