Interventions for prevention of giant retinal tear in the fellow eye

Abstract

Background

A giant retinal tear is a full‐thickness retinal break that extends circumferentially around the retina for 90 degrees or more in the presence of a posteriorly detached vitreous. It causes significant visual morbidity from retinal detachment and proliferative vitreoretinopathy. The fellow eye of patients who have had a spontaneous giant retinal tear has an increased risk of developing a giant retinal tear, a retinal detachment or both. Interventions such as 360‐degree encircling scleral buckling, 360‐degree cryotherapy and 360‐degree laser photocoagulation have been advocated by some ophthalmologists as prophylaxis for the fellow eye against the development of a giant retinal tear and/or a retinal detachment, or to prevent its extension.

Objectives

To evaluate the effectiveness of prophylactic 360‐degree interventions in the fellow eye of patients with unilateral giant retinal tear to prevent the occurrence of a giant retinal tear, a retinal detachment or both.

Search methods

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 11), MEDLINE (January 1950 to December 2011), EMBASE (January 1980 to December 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to December 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled‐trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 6 December 2011. In addition, we searched the proceedings of the Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO) up to 2008 for information about other relevant studies.

Selection criteria

Prospective randomised controlled trials (RCTs) comparing one prophylactic treatment for fellow eyes of patients with giant retinal tear against observation (no treatment) or another form of prophylactic treatment. In the absence of RCTs, we planned to discuss case‐control studies that met the inclusion criteria but we would not conduct a meta‐analysis using these studies.

Data collection and analysis

We did not find any studies that met the inclusion criteria for the review and therefore no assessment of methodological quality or meta‐analysis could be performed.

Main results

No studies met the inclusion criteria for this review.

Authors' conclusions

No strong evidence in the literature was found to support or refute prophylactic 360‐degree treatments to prevent a giant retinal tear or a retinal detachment in the fellow eye of patients with unilateral giant retinal tears.

Plain language summary

Interventions for prevention of giant retinal tear in the fellow eye

A giant retinal tear is a full‐thickness retinal break that extends for 90 degrees or more around the circumference of the retina, in the presence of posterior vitreous detachment (when the vitreous comes away from the retina). Giant retinal tears cause visual loss as a result of the associated retinal detachment. They can be difficult to treat due to the large area of retinal involvement and the high risk of re‐detachment following vitreoretinal surgery, often related to the development of proliferative vitreoretinopathy (a scarring process that can happen on the inner or outer surface of the retina and in the vitreous cavity after retinal detachment). As the fellow eye has an increased risk of developing giant retinal tear and retinal detachment, prophylactic 360‐degree treatments with laser photocoagulation, cryotherapy or encircling scleral buckling have been proposed to reduce this risk. This review did not find any strong evidence in the form of prospective randomised controlled trials or case‐control studies to support or refute these prophylactic treatments.

Background

Description of the condition

A giant retinal tear (GRT) is a full‐thickness retinal break that extends circumferentially around the retina for three or more clock hours (90 degrees or more) in the presence of a posteriorly detached vitreous (Freeman 1978; Glasspool 1973; Kanski 1975; Schepens 1962; Scott 1975). It is an uncommon retinal condition with a guarded prognosis, as it can cause significant visual morbidity from retinal detachment. Recurrent retinal detachment, predominantly due to proliferative vitreoretinopathy (PVR), occurs in up to 49% of GRT cases (Ghosh 2004; Kertes 1997; Malbran 1990; Rofail 2005; Scott 2002). Proliferative vitreoretinopathy is a scarring process that can occur on the inner or outer retinal surface and in the vitreous cavity following retinal detachment, which may lead to surgical failure even following initial successful surgical repair. The high incidence of PVR from GRT (up to 78%) may be due to several factors, including the release of a high number of retinal pigment epithelial cells from the subretinal space into the vitreous cavity as a result of the large area of exposed retinal pigment epithelium, and the increased cytokine production by these cells and by blood‐borne cells from any concurrent clinical or sub‐clinical associated vitreous haemorrhage (Duquesne 1996; Girard 1994; Kon 1999; Leaver 1981; Malbran 1990; Tseng 2004; Yeung 2008; Yoshino 1989). Surgical treatment of GRT can therefore be extremely challenging.

The annual incidence of GRT has not been clearly established in the literature. It has been estimated to be 0.05 per 100,000 of the general population per year, or 0.5% of all cases of retinal detachments resulting from retinal breaks (Freeman 1978). Predisposing factors for the development of a GRT include trauma, complicated and uncomplicated intraocular procedures, refractive surgery, acute retinal necrosis, high myopia and hereditary vitreoretinopathies such as Stickler syndrome (Aaberg 1997; Abu el‐Asrar 1997; Aylward 1993; Batman 1998; Clarkson 1984; Duguid 2000; Freeman 1978; Freeman 1979; Hernaez‐Ortega 2004; Kanski 1975; Lash 2004; Moore 2003; Navarro 2005; Ozdamar 1998; Rizzo 2003; Schepens 1962; Schipper 2000; Scott 1975; Topilow 1982; Vilaplana 1999; Yam 2008). Other more rare conditions that have been associated with GRT include aniridia, lens coloboma, microspherophakia, retinitis pigmentosa, endogenous endophthalmitis and Jarisch‐Herxheimer reaction in ocular syphilis (Cahill 1998; Dowler 1995; Hovland 1968; Jain 2002; Johnston 1985; Kim 1996; Pal 2005; Pournaras 2006). Patients usually present with acute, painless loss of vision in the affected eye. There may be preceding symptoms of flashing lights, floaters and/or a shadow over the field of vision. Dilated fundoscopy will confirm the diagnosis of GRT and the likely associated retinal detachment. Ultrasonography typically shows discontinuity of the high reflective linear retinal echo extending for more than three clock hours (Jalkh 1983). In addition, there is posterior vitreous detachment and, commonly, a central vitreous cavity due to vitreous syneresis and liquefaction (Genovesi‐Ebert 1998). Ultrasound is particularly useful in the event where no clear fundal view is achieved. It is also helpful to differentiate a GRT from a giant retinal dialysis, in which no posterior vitreous detachment would be observed.

The fellow eye of patients with a GRT, especially in spontaneous non‐traumatic cases, has an increased risk for developing GRT and retinal detachment. The development of bilateral GRT has been found to occur in 12.8% (average interval 3.5 years and maximum interval six years); this has been reported to be as high as 74% within five years for GRT occurring at the equator (Freeman 1978; Freeman 1979; Scott 1976). In Freeman's natural history series of 124 untreated fellow eyes, GRT occurred in 14 (11.3%) over a mean follow up of 3.7 years (Freeman 1978; Freeman 1979). Furthermore, retinal detachments of any aetiology may occur in up to 36% of fellow eyes (Freeman 1978; Freeman 1979; Glasspool 1973). Therefore, prophylactic treatments that may prevent the occurrence of GRT and retinal detachment or limit their extension would be extremely helpful to preserve vision in these patients.

Description of the intervention

Various prophylactic 360‐degree interventions have been advocated to reduce the risk of GRT and retinal detachment in the fellow eye, including circumferential encircling scleral buckling, cryotherapy and laser photocoagulation (Freeman 1978; Freeman 1979; Ghosh 2004; Glasspool 1973; Govan 1981; Wolfensberger 2003). For encircling scleral buckles, a 360‐degree silicone band is placed around the globe behind the insertion of the four rectus muscles and sutured to the sclera. The position of the encirclement varies in the literature: at the equator, or over areas of identified retinal pathology (Glasspool 1973; Hudson 1973). This is a surgical procedure that requires general anaesthesia or local anaesthesia via the retrobulbar, peribulbar or sub‐tenon routes with the subsequent risks and cost implications.

Cryotherapy is a technique that utilises intense cold from rapidly expanding very cold gases (usually nitrous oxide) to destroy choroidal and retinal tissue in order to form a chorioretinal scar. The cryotherapy is applied transsclerally or transconjunctivally, usually in one contiguous row, via a freezing probe at the peripheral retina throughout 360 degrees. The resultant 360‐degree chorioretinal scar increases the adhesion between the neurosensory retina and the retinal pigment epithelium. Different areas for cryotherapy have been advocated, with treatment at the post‐oral retina, at the posterior border of the vitreous base as determined by areas of “white‐with‐pressure”, and at the equator all having been described (Ang 2008; Govan 1981; Hudson 1977; Robertson 1979; Wolfensberger 2003). Like scleral buckling, cryotherapy requires general anaesthesia or local anaesthesia via the retrobulbar, peribulbar or sub‐tenon routes and is not often performed as an outpatient procedure.

In laser photocoagulation, the light energy from the laser is converted to thermal energy by the pigment contained in the retinal pigment epithelium. This thermal energy subsequently destroys the retinal pigment epithelium and leads to the formation of a chorioretinal scar, with a resultant increased adhesion between the neurosensory retina and retinal pigment epithelium. It involves applying multiple, small‐sized (up to 500 microns), high‐intensity laser burns to the peripheral retina over three to six rows throughout 360 degrees via direct or indirect viewing systems. Most published series in which this prophylactic method was used describe the application of laser to the equatorial retina; in some the laser was extended to the ora serrata with four anterior radial rows, while in others laser treatment was applied circumferentially posterior to the areas of vitreoretinal degeneration (Brasseur 1985; Haut 1987; Haut 1991; Madelain 1990; Meyer‐Schwickerath 1967; Pollack 1994). Unlike scleral buckling and cryotherapy, it is possible to perform laser as an outpatient procedure and without the need for general or even local anaesthesia, with the subsequent reduced risk and cost of the intervention.

How the intervention might work

It is believed that GRT would occur in areas of abnormal vitreoretinal adhesion and traction, often at the vitreous base, especially when there are already pre‐existing vitreoretinal degenerations that could predispose to the development of retinal breaks (Freeman 1978; Schepens 1962; Scott 1976). A 360‐degree encircling buckle would reduce the internal circumference of the eye at the site it is placed, thus reducing the amount of peripheral vitreoretinal traction. Cryotherapy and laser photocoagulation would result in an increased neurosensory retina‐retinal pigment epithelium adhesion (scar) over 360 degrees and would likely reduce the risk of neurosensory retinal detachment from the retinal pigment epithelium and/or limit its extension if it were to occur.

Why it is important to do this review

There is a strong argument in favour of using 360‐degree prophylaxis in fellow eyes of patients that have had a GRT, particularly in spontaneous non‐traumatic cases and those associated with inherited vitreoretinal disorders, such as Stickler syndrome. However, prophylactic interventions are not without possible adverse effects, such as uveitis, cystoid macular oedema, epiretinal membrane formation and iatrogenic retinal breaks, among others (Bonnet 1987; Govan 1981; Haut 1987; Hudson 1977; Madelain 1990; Pollack 1994; Robertson 1979). Although uncommon, they may result in reduction in vision. To the patient, prophylactic treatments may represent a hassle and a cause of discomfort. Furthermore, it is not certain whether or not these prophylactic measures would reduce the risk of GRT, retinal detachment and/or visual loss. Retinal detachment may still ensue if subsequent retinal breaks develop posterior to the treated areas. Even if these prophylactic treatments were to be helpful, there is no clear knowledge on which of them is most effective. It is therefore important to review the current evidence in favour of or against prophylaxis in fellow eyes of patients with unilateral GRT.

Objectives

The primary objective of this review is to determine whether or not prophylactic 360‐degree treatment against GRT is effective in reducing the risk of GRT, retinal detachment and subsequent visual loss in the fellow eye of patients with a unilateral GRT.

Methods

Criteria for considering studies for this review

Types of studies

We planned to include randomised controlled trials (RCTs) but if none met our inclusion criteria, we would discuss case‐control studies.

Types of participants

Any participant with a unilateral GRT, independent of their age, gender or ethnicity and independently of the aetiology of the GRT, was eligible for inclusion in this review.

Types of interventions

The prophylactic interventions were 360‐degree encircling scleral buckling, 360‐degree transscleral cryotherapy and 360‐degree laser photocoagulation. Studies comparing one of these prophylactic treatments against no treatment (control) or against another form of prophylactic treatment were included in this review.

Types of outcome measures

Primary outcomes

1. Relative risk of patients with unilateral GRT developing a GRT in the fellow eye within three years following prophylactic treatment compared to those that did not receive prophylactic treatment.

Secondary outcomes

1. Relative risk of patients with unilateral GRT developing a retinal detachment in the fellow eye within three years following prophylactic treatment compared to those that did not receive prophylactic treatment.

2. Relative risk of patients with unilateral GRT developing a fovea‐off retinal detachment in the fellow eye within three years following prophylactic treatment compared to those that did not receive prophylactic treatment.

3. Difference in the mean extension of GRT circumferentially (in clock hours) in the fellow eye within three years in those receiving prophylactic treatment compared to those that did not receive prophylactic treatment, and its standard error.

4. Difference in the mean extension of retinal detachment (in quadrants) in the fellow eye within three years in those receiving prophylactic treatment compared to those that did not receive prophylactic treatment, and its standard error.

5. Relative risk in patients with unilateral GRT of a decrease in Snellen visual acuity of two lines or more from baseline in the fellow eye within three years following prophylactic treatment compared to those that did not receive prophylactic treatment.

6. Relative risk of patients with unilateral GRT developing complications in the fellow eye from the prophylactic treatments within three years, compared to those that did not receive prophylactic treatment.

Adverse outcomes

The main adverse outcomes of prophylactic treatments will be classified into two categories:

1. Adverse outcomes with the potential to affect vision: these include refractive errors, raised intraocular pressure, anterior segment ischaemia, cataract, anterior and/or posterior uveitis, cystoid macular oedema, epiretinal membrane, retinal breaks and diplopia. Although some of these are likely to be the result of the prophylactic interventions (refractive errors, anterior segment ischaemia, uveitis, cystoid macular oedema, epiretinal membrane and diplopia), others may be coincidental (cataract) or related to the underlying disorder (retinal breaks). We also summarised any other adverse effects reported in the included studies with the potential to affect vision.

2. Adverse outcomes causing other symptoms but not affecting vision: these included discomfort, dryness and exposure of the encirclement elements, among others.

Economic data

Economic data were not available.

Quality of life data

Quality of life data were not available.

Search methods for identification of studies

Electronic searches

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2011, Issue 11, part of The Cochrane Library. www.thecochranelibrary.com (accessed 6 December 2011), MEDLINE (January 1950 to December 2011), EMBASE (January 1980 to December 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to December 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled‐trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no language or date restrictions in the search for trials. The electronic databases were last searched on 6 December 2011.

See: Appendices for details of search strategies for CENTRAL (Appendix 1), MEDLINE (Appendix 2), EMBASE (Appendix 3), LILACS (Appendix 4), mRCT (Appendix 5), ClinicalTrials.gov (Appendix 6) and the ICTRP (Appendix 7).

Searching other resources

We searched the reference lists of the retrieved articles and the proceedings of the Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO) for information about other relevant studies on prophylaxis of GRT in the fellow eye of patients with unilateral GRT. We searched the ARVO meeting abstracts from 1962 to 2008.

Data collection and analysis

Selection of studies

Two authors independently assessed the titles and abstracts of all reports identified by the electronic and manual searches. Each report was labelled 'definitely exclude', 'unsure' or 'definitely include'. We excluded studies labelled as 'definitely exclude' from the review. We reassessed studies labelled as 'unsure' according to the inclusion criteria for this review. We assessed studies labelled as 'definitely include' for methodological quality. We resolved any differences between the two authors with regards to the above classification by discussion. We found all studies to be classified as 'definitely exclude' and, thus, identified no studies that met the inclusion criteria.

In future updates of this review, if we find RCTs that meet our inclusion criteria, we will follow the methodological process identified below.

Data extraction and management

Two authors will extract data independently using a paper form developed by the Cochrane Eyes and Vision Group. Two authors will check the data independently before it is entered in to RevMan (Review Manager 2011).

Assessment of risk of bias in included studies

We will assess the risk of bias of any included studies according to the guidelines in Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will consider the following criteria:

• Random sequence generation: we will describe the method used to generate the allocation sequence in detail.

• Allocation concealment: we will describe the method used to conceal the allocation sequence.

• Masking (blinding) of participants and outcome assessors will be noted.

• Incomplete outcome data: we will describe exclusions, rates of follow up, reason for loss to follow up and intention‐to‐treat analysis.

• Selective outcome reporting will be evaluated.

• Other potential sources of bias will be discussed.

We will grade each of the above domains graded as:

• high risk of bias: when plausible bias seriously weakens the study results;

• low risk of bias: when plausible bias is unlikely to alter the study results; or

• unclear risk of bias: when plausible bias raises some doubt about the study results.

If any of the above domains is graded as 'unclear risk of bias', we will contact the investigators of the published eligible RCTs in order to obtain additional information. In the event of failure to communicate with the study investigators or failure to respond within a reasonable time period, we will assess the methodological quality of that trial based on the available information. We will resolve any disagreements on the above assessments between the authors through discussion until a consensus is reached.

Measures of treatment effect

We will summarise dichotomous outcomes as relative risk ratios, which will include:

1. relative risk of developing GRT in the fellow eye;

2. relative risk of developing a retinal detachment in the fellow eye;

3. relative risk of developing a fovea‐off retinal detachment in the fellow eye;

4. relative risk of a decrease in Snellen visual acuity of two lines or more from baseline in the fellow eye; and

5. relative risk of developing complications from the prophylactic treatments in the fellow eye.

We will summarise continuous outcomes as difference in means and its standard error, which will include:

1. difference in mean extent of GRT circumferentially (in clock hours) in the fellow eye, and its standard error; and

2. difference in mean extent of retinal detachment (in quadrants) in the fellow eye, and its standard error.

Unit of analysis issues

In the analysis, we will compare treated fellow eyes with non‐treated fellow eyes in patients with unilateral GRT.

Dealing with missing data

We expect studies to be analyzed on an intention‐to‐treat basis. If there is no information about the characteristics of any missing data, this will raise concerns regarding whether the missing data may introduce any bias or not. Where data are missing or unclear, we will contact the authors for clarification and further information.

Assessment of heterogeneity

We will test for heterogeneity by looking at the overlap in confidence intervals of the forest plot, and using the Chi² test and the I² statistic as defined in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011). We will use the I² statistic to assess the proportion of total variability explained by heterogeneity between studies.

Assessment of reporting biases

We will assess sequence generation, allocation concealment, masking of participants and outcome assessors, incomplete outcome data, selective outcome reporting and other potential sources of bias as above. We will use funnel plots to assess publication bias in reported studies.

Data synthesis

We will perform data analysis according to the guidelines set out in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011). We will use a random‐effects model. If there is no statistical or clinical heterogeneity, or if the number of trials is fewer than three, we will use a fixed‐effect model to avoid reporting potential poor effect estimates due to random‐effects models in situations with very few trials.

We will perform a meta‐analysis for the following outcomes: relative risk of developing a GRT in the fellow eye within three years (primary outcome), relative risk of developing a retinal detachment in the fellow eye within three years (secondary outcome), and relative risk of a decrease in Snellen visual acuity of two lines or more from baseline in the fellow eye within three years (secondary outcome).

Sensitivity analysis

We will examine the impact of excluding studies with lower methodological quality, unpublished data and industry funded data in sensitivity analyses.

Results

Description of studies

The electronic searches found 162 titles and abstracts. The Trials Search Co‐ordinator scanned the search results and removed 144 references which were not relevant to the scope of the review. We scanned the remaining 18 references but none met the inclusion criteria. We then searched the reference lists of the retrieved articles to identify additional studies and found 54 citations. Of these, we excluded 43 references: 22 evaluated prophylactic treatment of predisposing vitreoretinal lesions while 21 assessed prophylactic treatment of fellow eyes of retinal detachments; these were not specifically investigating fellow eyes of GRT. Only 12 articles were pertinent to the review, but none were RCTs or case‐control studies. There were only five publications describing 360‐degree prophylaxis in GRT fellow eyes that had a sample size of three or more.

Of the 12 articles mentioned above, two were referring to local treatment of predisposing vitreoretinal lesions and nine to circumferential treatment over 360 degrees for fellow eyes of patients with unilateral GRT.

Local prophylactic treatments were evaluated in two case series; one investigated the role of local treatments to predisposing lesions or high‐risk areas in 11 GRT fellow eyes (Kreissig 1983). The other evaluated local treatments for 150 retinal detachment fellow eyes considered at “high risk”; these included five GRT fellow eyes (Mastropasqua 1999).

The ten publications describing 360‐degree treatments consisted of two case reports and eight retrospective case series. The two case reports comprised three fellow eyes of patients with GRT, and described prophylaxis with 360‐degree laser photocoagulation (Brasseur 1985; Meyer‐Schwickerath 1967).

Of the eight retrospective case series, one assessed prophylactic 360‐degree cryotherapy in 48 fellow eyes of spontaneous GRT (Wolfensberger 2003). The second case series described 55 eyes that had prophylactic treatment with either 360‐degree encircling scleral buckle at the equator for “higher risk” eyes or local cryotherapy to “lower risk” eyes with predisposing vitreoretinal lesions (Freeman 1978; Freeman 1979). The third series predominantly focused on the prognostic factors of GRT outcomes following vitrectomy in 117 eyes, but included 21 fellow eyes of spontaneous GRT treated with either 360‐degree cryotherapy or laser photocoagulation (Al‐Khairi 2008). The fourth study evaluated 360‐degree cryotherapy in fellow eyes of GRT, aphakic retinal detachment and high myopia, and included 18 GRT fellow eyes (Govan 1981). The fifth case series primarily investigated the surgical treatment and outcome of GRT in 29 eyes, but also described the outcomes of prophylactic 360‐degree laser photocoagulation or cryotherapy in 18 fellow eyes (Ghosh 2004). The sixth assessed 360‐degree encircling scleral buckle in conjunction with local cryotherapy for the fellow eye of three patients (Glasspool 1973). Details on these six case series are provided in Table 1 and will be discussed below.

1. Summary of case series assessing prophylactic 360‐degree interventions of fellow eyes of patients with spontaneous unilateral giant retinal tear.

Study name	Methods	Participants	Intervention	Follow up	Outcomes
Al‐Khairi 2008	Retrospective	21 fellow eyes of 21 patients with spontaneous GRT	360‐degree laser or cryotherapy	Mean 30 months	No case of GRT 1 case of RD (no data on time lag) No data on complications
Freeman 1978; Freeman 1979	Retrospective	55 fellow eyes of 55 patients with non‐traumatic GRT	360‐degree encircling scleral buckle or local cryotherapy	Mean 44 months	1 case of GRT at 36 months 1 case of RD at 5 months 1 transient vitreous haemorrhage
Ghosh 2004	Retrospective	18 fellow eyes of 18 patients with spontaneous GRT	360‐degree laser or cryotherapy	Mean 28 months	No case of GRT No data on RD No data on complications
Glasspool 1973	Retrospective	3 fellow eyes of 3 patients with spontaneous GRT	360‐degree encircling scleral buckling combined with local cryotherapy	Mean 18 months	No case of GRT No case of RD No data on complications
Govan 1981	Retrospective	106 eyes at 'high risk' of retinal detachment; includes 18 fellow eyes of 18 patients with GRT	360‐degree cryotherapy	Mean 29 months	No case of GRT 3 cases of RD at 28, 36 and 54 months respectively Complications in 14 (13.2%): 3 anterior uveitis, 3 cystoid macular oedema after cataract surgery, 2 transient loss of accommodation, 1 fixed dilated pupil, 2 cataract, 1 vitreous haemorrhage, 1 epiretinal membrane, 1 retinal haemorrhage, 1 choroidal haemorrhage
Wolfensberger 2003	Retrospective	48 fellow eyes of 48 patients with spontaneous GRT	360‐degree cryotherapy	Mean 84 months	1 case of GRT at 6 months 2 cases of RD at 6 and 11 months respectively No complications

GRT: giant retinal tear 
 RD: retinal detachment not due to giant retinal tear

The seventh case series evaluated 360‐degree encircling buckle for fellow eyes of retinal detachment, and included two GRT fellow eyes (Hudson 1973). The final series reported 360‐degree cryotherapy for patients with Type 1 Stickler syndrome, which is the commonest inherited cause of GRT (Ang 2008). This series included 31 eyes of 31 patients with this disease who have had a retinal detachment in the first eye; however, data on the number of first eyes with GRT in the first eye were unavailable.

An update search was done in October 2009. After deduplication the search identified a total of 14 references. Two authors independently reviewed the references but did not find any relevant reports of trials.

A further update search was done in December 2011. After deduplication the search identified a total of 25 references. The Trials Search Co‐ordinator scanned the search results and removed 24 references which were not relevant to the scope of the review. We reviewed the remaining reference but it did not meet the inclusion criteria for the review.

Risk of bias in included studies

As no studies fulfilled the inclusion criteria for the review, risk of bias was not assessed.

Effects of interventions

As no studies fulfilled the inclusion criteria for the review, the effect of interventions could not be assessed.

Discussion

This review found no prospective RCTs or case‐control studies on prophylactic treatments for fellow eyes of patients with unilateral GRT. The literature on this topic is scarce.

In the largest case series (48 eyes) of prophylactic 360‐degree cryotherapy administered to fellow eyes of patients with spontaneous GRT, only one (2.1%) fellow eye developed GRT and two others (4.2%) developed a non‐GRT retinal detachment after a mean follow up of 84 months (Wolfensberger 2003). The fellow eye that developed GRT did so six months after prophylactic cryotherapy; the two non‐GRT retinal detachments occurred after 11 and 36 months respectively. No complications were described, but the possibility of the GRT and two retinal detachments occurring as a result of the 360‐degree cryotherapy could not be excluded.

Freeman's follow up of 226 non‐traumatic GRT fellow eyes included 55 eyes that had prophylactic treatment with either 360‐degree encircling scleral buckle for “higher risk” eyes or local cryotherapy to “lower risk” predisposing vitreoretinal lesions (Freeman 1978; Freeman 1979). “Higher risk” eyes included those with retinal tears, high myopia and increasing white‐with‐pressure. Over a mean follow‐up period of 44 months, one of the fellow eyes (treated with 360‐degree scleral buckling) developed GRT, in contrast to 11.3% (14 of 124) in the untreated eyes. One (treated with local cryotherapy) developed a non‐GRT retinal detachment, while this occurred in nine of the 124 (7.3%) untreated eyes. The only complication noted was transient vitreous haemorrhage in one eye that underwent 360‐degree encircling scleral buckle.

Of the 117 GRT eyes in Al‐Khairi's study, 21 were fellow eyes of spontaneous GRT that received either prophylactic 360‐degree laser photocoagulation or cryotherapy, whilst a further 42 fellow eyes did not. After a mean duration of 30 months, only one of the 21 (4.8%) treated eyes experienced a retinal detachment. In contrast, among the 42 untreated fellow eyes, GRT occurred in two (4.8%) and retinal detachment in a further three (7.1%) (Al‐Khairi 2008).

A separate study reported on 360‐degree cryotherapy (one row) to the equator in 106 eyes considered at ‘high risk’ of retinal detachment (18 GRT fellow eyes, 60 aphakic retinal detachment fellow eyes, 10 phakic retinal detachment fellow eyes, and 18 with high myopia) followed up over a mean of 29 months (Govan 1981). Of the 18 GRT fellow eyes, none developed GRT, however, three (16.7%) developed retinal detachment after 28, 36 and 54 months respectively. None were fovea‐off detachments, with two (11.2%) occurring anterior to the cryotherapy barrier and one (5.6%) at an area of non‐confluent scarring within the barrier. Complications were noted in 14 (13.2%) of the 106 treated eyes, but it was not stated if these occurred in the 18 treated GRT fellow eyes. The complications were acute anterior uveitis (three eyes), cystoid macular oedema following cataract surgery (three eyes), transient loss of accommodation (two eyes), fixed dilated pupil (one eye), cataract (one eye), vitreous haemorrhage (one eye), epiretinal membrane (one eye), retinal haemorrhage (one eye) and choroidal haemorrhage (one eye).

In a smaller case series of 29 patients with unilateral GRT, of which six were traumatic and 23 spontaneous, none of the 18 fellow eyes of spontaneous GRT treated prophylactically with 360‐degree laser photocoagulation or cryotherapy developed GRT after a mean follow up of 28 months (Ghosh 2004). Of the remaining five untreated fellow eyes of spontaneous GRT, three developed GRT within two to four weeks of the primary GRT surgery, before prophylactic treatment could be performed. The other two eyes were not prophylactically treated in accordance with the patients' requests; neither developed GRT or retinal detachment after a follow up of 36 months.

The final case series described local cryotherapy to all retinal breaks and degenerative areas with additional 360‐degree encircling scleral buckle so that the areas of retinal pathology would rest on the anterior slope of the indent. This was performed for three fellow eyes of patients with unilateral GRT; none developed a GRT or a retinal detachment after a mean follow up of 18 months (Glasspool 1973).

The results from the case series described above suggest that 360‐degree prophylactic treatment of the fellow eye may reduce the risk of GRT (11.3% to 74% untreated; up to 2.1% treated), and possibly of non‐GRT retinal detachment (7.3% to 36% untreated; up to 16.7% treated). Although no comparisons can be adequately established among these series, results do not indicate any significant advantage or disadvantage of one form of prophylaxis over the other. Any adverse effects from these interventions were mostly mild and self‐limiting, and did not lead to visual loss. The complication rates in these studies compare favourably with the incidence of complications as reported for these interventions in the literature. Depending on the study, these range from 0% to 23.1% for 360‐degree encircling scleral buckling, 0% to 13.2% for 360‐degree cryotherapy, and 0% to 3.8% for 360‐degree laser photocoagulation (Ang 2008; Govan 1981; Haut 1987; Haut 1991; Hudson 1973; Hudson 1977; Madelain 1990; Pollack 1994; Robertson 1979).

As vitreous liquefaction and vitreous base contraction are important in GRT pathogenesis, 360‐degree encircling scleral buckling may help by reducing the traction exerted by the vitreous base on the peripheral retina. This prophylactic method, however, entails a surgical procedure and is associated with buckle‐related complications. Cryotherapy and laser photocoagulation would not reduce or prevent the occurrence of vitreous traction. Hence, retinal tears and subsequent retinal detachment could still occur and have been reported posterior to the cryotherapy and laser scars (Bonnet 1987). However, both increase the adhesion of the neurosensory retina to the retinal pigment epithelium, thus reducing the possibility of the development of retinal tears and limiting their extension and that of a subsequent retinal detachment.

Currently, there is no strong evidence in the form of a RCT or a case‐control study to support or refute the use of 360‐degree prophylactic treatments for fellow eyes of patients with unilateral GRT. Data from available case series, however, suggest a benefit of 360‐degree prophylactic treatments in reducing the incidence of GRT and retinal detachments in fellow eyes of patients with unilateral GRT. Considering the observed increased risk in fellow eyes of patients with idiopathic GRT and of those with inherited vitreoretinal diseases such as Stickler syndrome, and the reported low rate of complications, 360‐degree prophylactic treatments may be considered in these patients.

Authors' conclusions

Implications for practice.

There is currently no evidence in the form of prospective RCTs or case‐control studies to support or refute the use of prophylactic 360‐degree treatment of the fellow eye of patients with unilateral GRT. However, given the high incidence of GRT and retinal detachment reported in patients with idiopathic GRT and those associated with inherited vitreoretinal diseases such as Stickler syndrome, the observed reduced risk of GRT and retinal detachment following prophylaxis in published case series, and the relative low rate of complications of prophylactic treatments, prophylaxis of fellow eyes may be considered for these patients. Based on data from Freeman 1978; Freeman 1979 and Wolfensberger 2003, although they may not be directly comparable, it can be estimated that the number of patients needed to treat (NNT) to prevent a GRT is 10.9, whilst the NNT to prevent a retinal detachment (related to a GRT or any other type of tear) is 8.1. This further suggests that prophylactic treatment is a reasonable option for fellow eyes of patients with unilateral GRT.

Implications for research.

Randomised controlled trials evaluating the clinical and cost‐effectiveness of prophylaxis with 360‐degree encircling scleral buckling treatments, cryotherapy or laser photocoagulation of fellow eyes of patients with unilateral GRT would be ideal to provide the strong evidence required to guide clinicians on the use of these prophylactic treatments. Such trials should compare one form of prophylactic treatment against observation (no treatment) or another form of treatment, be appropriately powered (i.e. sufficient numbers of participants) and have a relatively long‐term follow up (over three years). However, undertaking such RCTs would be challenging. Considering the published incidence of GRT in fellow eyes (11.3% in untreated eyes (Freeman 1978) and 2.1% in treated eyes (95% confidence interval 0 to 6.1%; Wolfensberger 2003), a RCT with 655 patients per arm would be required to provide 90% power to detect a reduction in the incidence of GRT from 11.3% to 6.1% or less.

What's new

Date	Event	Description
12 December 2011	New search has been performed	Issue 2 2012: Electronic searches were updated but no new studies were identified for inclusion in this update.
12 December 2011	New citation required but conclusions have not changed	Issue 2 2012: Minor editing done to review text.

History

Protocol first published: Issue 1, 2008
 Review first published: Issue 2, 2009

Date	Event	Description
4 November 2009	New search has been performed	Issue 1, 2010: updated searches yielded no RCTs. One retrospective study Al‐Khairi 2008 (which was identified from the original search) has been added to the discussion section.
6 August 2008	Amended	Converted to new review format.

Appendices

Appendix 1. CENTRAL search strategy

#1 MeSH descriptor Retinal Perforations 
 #2 MeSH descriptor Retinal Detachment 
 #3 giant near retin* near tear* 
 #4 retin* near break* 
 #5 retin* near tear* 
 #6 retin* near detach* 
 #7 retin* near perforat* 
 #8 (#1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7) 
 #9 MeSH descriptor Scleral Buckling 
 #10 scleral near buckl* 
 #11 scleral near encircl* 
 #12 encircling band 
 #13 MeSH descriptor Cryotherapy 
 #14 cryotherap* 
 #15 MeSH descriptor Light Coagulation 
 #16 laser* near photocoagulat* 
 #17 (#9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15 OR #16) 
 #18 prophyla* 
 #19 prevent* 
 #20 ameliorate* 
 #21 (#18 OR #19 OR #20) 
 #22 (#8 AND #17) 
 #23 (#21 AND #22)

Appendix 2. MEDLINE search strategy

1. randomized controlled trial.pt. 
 2. (randomized or randomised).ab,ti. 
 3. placebo.ab,ti. 
 4. dt.fs. 
 5. randomly.ab,ti. 
 6. trial.ab,ti. 
 7. groups.ab,ti. 
 8. or/1‐7 
 9. exp animals/ 
 10. exp humans/ 
 11. 9 not (9 and 10) 
 12. 8 not 11 
 13. case‐control studies/ 
 14. (case adj2 control$).tw. 
 15. or/13‐14 
 16. 12 or 15 
 17. retinal perforations/ 
 18. retinal detachment/ 
 19. (giant adj2 retina$ adj2 tear$).tw. 
 20. (retina$ adj2 break$).tw. 
 21. (retina$ adj2 tear$).tw. 
 22. (retina$ adj2 detach$).tw. 
 23. (retina$ adj2 perforat$).tw. 
 24. or/17‐23 
 25. scleral buckling/ 
 26. (scleral adj2 buckl$).tw. 
 27. (scleral adj2 encircl$).tw. 
 28. encircling band.tw. 
 29. exp cryotherapy/ 
 30. cryotherap$.tw. 
 31. exp light coagulation/ 
 32. (laser adj2 photocoagulat$).tw. 
 33. or/25‐32 
 34. 24 and 33 
 35. prophyla$.tw. 
 36. prevent$.tw. 
 37. ameliorate$.tw. 
 38. or/35‐37 
 39. 34 and 38 
 40. 16 and 39

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

Appendix 3. EMBASE search strategy

1. exp randomized controlled trial/ 
 2. exp randomization/ 
 3. exp double blind procedure/ 
 4. exp single blind procedure/ 
 5. random$.tw. 
 6. or/1‐5 
 7. (animal or animal experiment).sh. 
 8. human.sh. 
 9. 7 and 8 
 10. 7 not 9 
 11. 6 not 10 
 12. exp clinical trial/ 
 13. (clin$ adj3 trial$).tw. 
 14. ((singl$ or doubl$ or trebl$ or tripl$) adj3 (blind$ or mask$)).tw. 
 15. exp placebo/ 
 16. placebo$.tw. 
 17. random$.tw. 
 18. exp experimental design/ 
 19. exp crossover procedure/ 
 20. exp control group/ 
 21. exp latin square design/ 
 22. or/12‐21 
 23. 22 not 10 
 24. 23 not 11 
 25. exp comparative study/ 
 26. exp evaluation/ 
 27. exp prospective study/ 
 28. (control$ or prospectiv$ or volunteer$).tw. 
 29. or/25‐28 
 30. 29 not 10 
 31. 30 not (11 or 23) 
 32. 11 or 24 or 31 
 33. case control study/ 
 34. (case$ adj2 control$).tw. 
 35. or/33‐34 
 36. 32 or 35 
 37. retina tear/ 
 38. exp retina detachment/ 
 39. (giant adj2 retina$ adj2 tear$).tw. 
 40. (retina$ adj2 break$).tw. 
 41. (retina$ adj2 tear$).tw. 
 42. (retina$ adj2 detach$).tw. 
 43. (retina$ adj2 perforat$).tw. 
 44. or/37‐43 
 45. sclera buckling procedure/ 
 46. (scleral adj2 buckl$).tw. 
 47. (scleral adj2 encircl$).tw. 
 48. encircling band.tw. 
 49. exp cryotherapy/ 
 50. cryotherap$.tw. 
 51. exp laser coagulation/ 
 52. (laser adj2 photocoagulat$).tw. 
 53. or/45‐52 
 54. prophyla$.tw. 
 55. prevent$.tw. 
 56. ameliorate$.tw. 
 57. or/54‐56 
 58. 44 and 53 and 57 
 59. 36 and 58

Appendix 4. LILACS search strategy

retina$ and break$ or tear$ or detach$ or perforat$ and proph$ or prevent$ or ameliorate$

Appendix 5. metaRegister of Controlled Trials search strategy

giant retinal tear

Appendix 6. ClinicalTrials.gov search strategy

(Prophylactic OR Prevent OR Ameliorate) AND (Giant Retinal Tear)

Appendix 7. ICTRP search strategy

Giant Retinal Tear

Contributions of authors

NL conceived the review question, provided a policy and consumer perspective, provided general advice and secured funding for the review. 
 GSA co‐ordinated the review, undertook manual searches, organised retrieval of full‐text copies. 
 NL and GSA screened the titles and abstracts of search results, screened retrieved papers against inclusion criteria, appraised quality of papers, wrote to authors of studies for additional information, provided additional data about papers, obtained and screened data for unpublished studies and provided a clinical perspective. 
 NL, GSA and JT extracted data from papers, entered data into RevMan, analyzed data, provided a methodological perspective and wrote the review.

Update of review Issue 2, 2011 
 GSA and Cochrane Eyes and Vision Group's (CEVG) Trials Search Co‐ordinator (TSC) screened search results. 
 CEVG's Managing Editor and TSC updated the review (minor edits).

Declarations of interest

None known.

New search for studies and content updated (no change to conclusions)