A Database Study of Vitreomacular Traction

Timothy L Jackson PhD, FRCOphth1, Paul HJ Donachie MSc2, and Robert L Johnston FRCOphth2 for the Vitreomacular Traction Study Group*

King’s College London1 and Gloucestershire Hospitals NHS Foundation Trust,

Cheltenham2, United Kingdom.

*Collaborators (Vitreomacular Traction Study Group): Fiona Bishop, Ted Burton, Ahmed El-

Amir, Paul H.J. Donachie, Alan Fitt, Steven Harsum, Richard Haynes, Julian Hickman-Casey,

Timothy L. Jackson (Chair), Robert L. Johnston, Dominic McHugh, Richard Newsom, Rubina

Rahman, Martin Snead, Steve Winder, Yit Fung Yang, Rahila Zakir, and Hadi Zambarakji.

Word count: 3673.

Proprietary Interest and Funding: T. Jackson and P. Donachie’s employer received

unrestricted funding from Alcon-ThromboGenics to analyse these data. Alcon-

ThromboGenics had no data access, nor any input in the study design, data analysis,

or manuscript preparation, with no opportunity to review the manuscript prior to

first submission.

Correspondence and requests for reprints

Timothy L JacksonKing’s College LondonDepartment of OphthalmologyKing’s College HospitalLondon SE5 9RSEmail: t.jackson1@nhs.netTel: +44 20 3299 3385Fax: + 44 20 3299 3738.

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KEY WORDS

Database study; vitreomacular traction; vitreomacular adhesion; natural history;

pars plana vitrectomy; complications; cataract; United Kingdom; surgery; audit.

SUMMARY STATEMENT

A database study of 1,399 eyes with vitreomacular traction found that vitrectomy

was associated with intraoperative complications in 11.5% of cases and retinal

detachment in 2.7%. Only 36% gained two Snellen lines or more.

ABSTRACT

Purpose: To audit the natural history of vitreomacular traction (VMT), and the risks

and benefits of surgery.

Methods: Database study of 1,254 patients (1,399 eyes) with VMT from 16 United

Kingdom vitreoretinal units.

Results: The median age was 75 years, with 36.2% of patients diagnosed as diabetic.

In 986 (70.5%) eyes managed conservatively, the median presenting visual acuity

(VA) of 10/20 was unchanged over 10.8 months. Of 413 eyes (29.5%) that required

pars plana vitrectomy, the median preoperative logarithm of the minimum angle of

resolution VA improved from 0.60 to 0.50 (5/20 to 6/20), with 36% gaining at least

0.3 units (approximately 2 Snellen lines). Vitrectomy was combined with internal

limiting membrane peel in 43.8%, epiretinal membrane peel in 42.4%, gas/air

tamponade in 46.2%, and cataract surgery in 27.9%. One or more intraoperative

complication occurred in 11.5%; most commonly retinal breaks (8.0%), retinal

trauma (1.9%), and retinal hemorrhage (1.0%). Postoperative retinal detachment

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occurred in 2.7% and macular hole in 2.2%. The 1, 2 and 3 year rates of post-

vitrectomy cataract surgery were 28.2%, 38.2% and 42.7% respectively.

Conclusion: Many eyes with VMT have stable VA. Those progressing to vitrectomy

have relatively modest VA gains, and complications are not infrequent.

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INTRODUCTION

Vitreomacular traction (VMT) syndrome occurs in the context of an incomplete

posterior vitreous detachment (PVD), where persisting macular adhesion leads to

distortion of the macular anatomy. It can be associated with variable loss of visual

function manifest as distortion, metamorphopsia, and reduced visual acuity (VA).

Traditionally there are two main management options, pars plana vitrectomy (PPV)

or observation, the latter in the expectation that some eyes will resolve

spontaneously.1-9 A recent meta-analysis of PPV for VMT revealed that only one third

of eyes gained two or more Snellen lines.10 Equally, observation may have

disadvantages, with a natural history study reporting that only 11% of eyes showed

spontaneous resolution over a mean follow up of 5 years, whereas 64% of eyes lost

at least two Snellen lines over this timeframe.11 Spontaneous resolution may be

more frequent in eyes without coexisting epiretinal membranes and with small areas

of adhesion, but conversely VMT can progress to macular hole.12, 13

More recently, ocriplasmin has been licensed for the treatment of symptomatic

vitreomacular adhesion. Ocriplasmin is given as an intravitreal injection, and is

designed to dissolve the vitreous and loosen its adhesion to the internal limiting

membrane (ILM).14-17 A recent, large, double-masked, randomized controlled trial

reported that vitreomacular adhesion was fully resolved in 26.5% of cases following

a single intravitreal injection of 125 µg of ocriplasmin.16 Other authors have reported

pilot data using an intravitreal gas injection to mechanically release VMT, with 6 of

15 cases (40%) responding.18

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A systematic review identified several important gaps in the literature on VMT.10 In

particular, few peer reviewed reports detailed the natural history of VMT, making it

hard for clinicians and patients to determine the risks and benefits of the treatment

options. Also, there are no large randomised controlled trials of PPV for VMT, and

most of the literature arises from uncontrolled, single centre studies.

This database study aimed to provide further insight into the routine management

and clinical course of VMT syndrome, and the risks and benefits of surgery.

MATERIALS and METHODS

Data extraction

Data were extracted on eyes diagnosed with VMT between June 2006 and December

2012 from 16 participating vitreoretinal units. All data were captured using one

electronic medical record (EMR) system (Medisoft Ophthalmology, Medisoft Limited,

Leeds, UK), and then pooled for analysis. The lead clinician and Caldicott Guardian

(who oversees data protection) at each hospital gave written approval for the data

extraction. Anonymized database analyses of this type do not require ethical

permission as they are viewed as audit or service evaluation.19 This study was

conducted in accordance with the declaration of Helsinki, and the UK’s Data

Protection Act. It was routine practice at all sites for nurses to record a pre-operative

assessment on the EMR, during which a standardised set of questions were asked in

relation to systemic comorbidities and the use of topical and systemic medications.

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Surgical complications

The EMR required surgeons to record whether or not there were any surgical

complications, before they could save the operation note. If the surgeon indicated

that a complication occurred, then he or she had to select from a pre-populated list

of well-recognised complications specific to that operation, or select ‘other’ and

record the complication using free text.

All hospitals using the EMR for vitreoretinal procedures also recorded cataract

surgery using the same system. It was therefore possible to estimate the incidence

of post-vitrectomy cataract surgery (PVCS).

Eligibility and Statistical Analysis

All eyes with a diagnosis of primary VMT were eligible. Eyes were excluded if they

had undergone PPV prior to VMT diagnosis, or if they had non-VMT eye surgery after

diagnosis and no record of VMT treatment.

The time to PVCS was modelled using the Kaplan-Meier method,20 with PVCS

modelled as failure. Eyes were censored at the last date on which follow up data of

any type was recorded on the EMR, if they had not had cataract surgery.

Visual acuity data were expressed as the logarithm of the minimum angle of

resolution (LogMAR), where the baseline measurements were taken at diagnosis for

the non-surgical eyes and day of surgery for the surgical eyes. We chose to primarily

report the median VA as the most appropriate VA outcome, but to allow comparison

with similar studies21-23 we also reported the mean VA by substituting CF, HM and PL

with 2.1, 2.4 and 2.7 respectively, where each step represents a doubling of the

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visual angle.24 For each substitution we provided the number of cases with CF, HM

and PL, so that other researchers could calculate mean VA using different values.

Visual success was defined as eyes improving by ≥0.30 LogMAR units (approximately

2 Snellen lines) from baseline and is reported at the last recorded VA measurement

(final review). All VA values less than 6 weeks after diagnosis or primary VMT surgery

(for the non-surgical and surgical groups respectively) were excluded and VA was

categorised as ≤0.30, >0.30 - 0.60, >0.60 - 0.90, >0.90 - 1.20, >1.20 at the time of

surgery and the last VA record. All analysis was conducted using STATA version 11

(StataCorp, College Station, TX) except for the confidence interval (CI) which were

calculate using Confidence Interval Analysis version 2.1.2.25

RESULTS

Patient demographics

Vitreomacular traction syndrome was diagnosed in 1,451 eyes from 1,301 patients

over the study period. Of these, 52 eyes from 47 patients were excluded from all

analyses: 17 as they had previously undergone PPV surgery at a median of 5 months

prior to VMT diagnosis, and 35 as they had non-VMT surgery after diagnosis and no

record of VMT treatment. Therefore 1,399 eyes (741 left eyes and 658 right eyes)

from 1,254 patients were eligible for analysis, of which 145 patients had bilateral

VMT.

Of the 1,254 patients, 507 (40.4%) were male, 746 (59.5%) were female and the

gender was not specified for 1 patient. The patient’s ethnicity was recorded for 919

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(73.3%) patients, where 830 were Caucasian, 52 Asian, 28 black, 6 mixed race and 3

other races. At the time of primary VMT diagnosis the median age was 75 years

(range; 11 – 98 years) and 624 (49.8%) patients were recorded as taking prescribed

medications; 134 eye drops only, 274 systemic medications only, and 216 both eye

drops and systemic medication.

Previous diseases and systemic comorbidities

Prior to primary VMT diagnosis 78 (6.2%) patients had experienced a myocardial

infarction, 64 (5.1%) a cerebrovascular accident and 59 (4.7%) a transient ischemic

attack. At the time of primary VMT diagnosis 611 (48.7%) patients were recorded as

having no systemic comorbidities, 350 (27.9%) one comorbidity, 155 (12.4%) two, 90

(7.2%) three, 37 (3.0%) four and 11 (0.9%) five comorbidities.

At the time of primary diagnosis 454 (36.2%) patients were record as having diabetes

mellitus, 296 (23.6%) hypertension, 66 (5.3%) angina, 58 (4.6%) suffering from

anxiety, panic attacks or claustrophobia, 51 (4.1%) hyperlipidemia, 46 (3.7%) asthma,

27 (2.2%) bronchitis, 27 (2.2%) hypercholesterolemia, 20 (1.6%) bleeding diathesis,

14 (1.1%) anemia, 7 (0.6%) cancer, 4 (0.3%) tuberculosis and 63 (5.0%) other non-

specified conditions.

Non-surgery eyes

Of the 1,399 eyes diagnosed with VMT, 986 (70.5%) eyes did not undergo surgery to

treat the disease (512 left eyes and 474 right eyes). The 986 non-surgical eyes were

from 862 patients (median age 75 years; range 30 – 96 years), 137 of whom had

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bilateral VMT. Data were recorded after diagnosis for 587 (59.5%) of the non-surgical

eyes for a median follow up time of 10.0 months (range: 1 day – 6.0 years). Of these,

54 had no VA measurement at the time of diagnosis, 20 had no VA measurements

recorded after diagnosis and 36 had less than 6 weeks follow up data recorded,

leaving 477 non-surgical eyes eligible for VA analysis. For these eyes the median VA

at diagnosis was 0.30 LogMAR units (Snellen 20/40) (mean 0.44; range: -0.20 – NPL)

including 10 eyes with CF, 3 with HM, 1 with PL and 1 with NPL. At the time of final

review after a median follow up of 10.8 months (range: 22 days – 5.4 years) the

median VA remained 0.30 LogMAR units (mean 0.47; range: -0.20 – HM) including 15

eyes with CF and 6 eyes with HM; 29 eyes (6.1%; 95% CI: 4.3% TO 8.6%) achieved

visual success (a gain of ≥0.30 LogMAR units, ≈2 Snellen lines).

There were no differences observed between patients progressing to surgery or not

for either gender or the age at diagnosis, but there were differences observed for

diabetic status and ethnicity, where a lower proportion of patients with diabetes had

surgery than did not (28.6% vs. 41.1%) and a lower proportion of patients from

ethnic minorities had surgery than did not (4.7% vs 8.3%). Both the diabetic status

and ethnicity were ‘not specified’ for many patients, although the observed

differences hold when these estimates are restricted to singleton eye patients with

the respective data.

Surgical technique, anaesthesia and setting

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Surgery was conducted on 413 of 1,399 (29.5%) eyes, of which 381 (92.2%) were

undertaken as day cases and 32 (7.8%) as inpatients. The 413 primary VMT

operations were performed on 229 left eyes and 184 right eyes from 405 patients

(median age 75 years; range 11 – 98 years) by 72 surgeons. Consultant surgeons

performed 272 (65.9%) of the operations, independent non-consultant surgeons,

including Fellows, 131 (31.7%) operations, and more junior trainee surgeons 10

(2.4%) operations.

All operations included PPV, which was combined with an ILM peel in 181 (43.8%),

epiretinal membrane (ERM) peel in 175 (42.4%), retinopexy in 98 (23.7%) and

cataract surgery in 115 (27.9%) operations. A tamponade was used in 194 (47.0%)

operations: 3 (0.7%) used silicone oil; 64 (15.5%) used sulfahexafluoride (SF6); 30

(7.3%) used hexafluoroethane (C2F6); 14 (3.4%) used perfluoropropane (C3F8); and 83

(20.1%) used air. For 78 (18.9%) operations the type of anaesthesia used was not

recorded on the EMR. For the remaining 335 operations general anaesthesia was

used for 43 operations (12.8%) and local anesthesia for 292 (87.2%), 7 with sedation.

Intraoperative complications

Of 413 operations, 361 (87.4%) were recorded as having no intraoperative

complication. Of the 52 (12.6%; 95% CI: 9.7% to 16.1%) eyes recorded as having a

complication, the most common was an iatrogenic tear, which occurred in 33

operations (Table 1). Two intraoperative complications occurred in 4 eyes. If the

complications associated with cataract surgery were excluded, then the complication

rate attributable to VMT surgery alone was 11.5% (47/408; 95% CI: 8.8% to 15.0%).

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Further surgery

Of the 413 eyes undergoing primary VMT surgery, 235 were excluded from the PVCS

analysis: 45 because they were known to have had previous cataract surgery; 115 as

they had combined VMT and cataract surgery; and 75 as they had less than 3 weeks

follow up. Of the remaining 178 eyes eligible for analysis, the median follow up was

8.2 months (range 22 days – 6.3 years), and 39 (21.9%) were subsequently recorded

as having cataract surgery. The 1, 2 and 3 year PVCS rates were 28.2%, 38.2% and

42.7% respectively (Figure 1).

Other subsequent operations, not related to cataract, occurred in 35 eyes, 8 of

which had more than 1 further surgery. A repeat VMT operation was performed in 7

(1.7%) eyes at a median of 3 months (range 0.6 - 7.4 months) after primary VMT

surgery; 11 (2.7%) eyes had retinal detachment surgery at a median of 1.9 months

(range 1 day - 12.6 months); 9 (2.2%) had macular hole surgery at a median of 5.9

months (range 2.2 - 10.0 months); and 11 (2.7%) had other types of vitreoretinal

surgery at a median of 2.8 months (range 11 days – 15.7 months).

Visual acuity change following surgery

Of the 413 eyes undergoing VMT surgery, 182 were excluded from the VA analysis as

they had no VA measurement at the time of surgery, 52 as they had no further VA

measurement and 19 as there was less than 6 weeks follow up VA data. From the

160 surgical eyes eligible for VA analysis the median preoperative LogMAR VA was

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0.60 (Snellen 20/80) (mean 0.69; range -0.10 – HM) which included 3 eyes with CF

and 1 with HM.

The last recorded VA measurement ranged from 6 weeks to 6.3 years (median 10.2

months) after primary VMT surgery. At this time the median VA was 0.50 (Snellen

20/63), the mean VA was 0.62 (Snellen 20/83), 58 eyes (36.3%; 95% CI: 29.2% to

43.9%) had achieved visual success, and the worst visual outcomes were CF in 5 eyes

and HMs in 2. Twenty-two eyes (13.8%) lost >0.30 LogMAR units at final review. Of

these, 7 had repeat surgery within this timeframe (1 for VMT, 1 for macular hole and

5 for retinal detachment) at a median of 2.0 months (range 0.6 – 12.6 months). The

worst visual outcomes were CF in 5 and HMs in 2 eyes. The general trend for

greatest VA improvement was for the eyes with preoperative VA in the middle of the

LogMAR scale (Figure 2).

Only 79 surgical eyes had VA data covering the period from diagnosis to surgery (the

others first appeared on the EMR at or near the time of surgery). These cases lost a

median of 0.04 logMAR units (mean 0.11, range -0.7 -to +0.3) over a median of 2.8

months prior to surgery (range 5 days – 2.5 years).

Of the 160 surgical eyes eligible for VA analysis 29 were known to be psuedophakic.

These eyes had a median VA at surgery of 0.60 LogMAR (Snellen 20/80), a mean VA

of 0.68 LogMAR (Snellen 20/96) and the range was 0.20 – CF which included 1 eye

with CF. At final review the median VA was 0.50 LogMAR (Snellen 20/63), the mean

VA was 0.65 LogMAR (Snellen 20/89) and the range was 0.00 – HM which included 2

eyes with HM. Visual success was achieved by 8 (27.6%) eyes and 3 (10.3%) eyes lost

>0.30 LogMAR units.

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Diabetic subgroup analysis

Because 36.2% of patients had diabetes we undertook a subgroup analysis of this

group. The 454 patients with diabetes contributed 500 eyes to the analysis, and of

these 115 eyes progressed to surgery and 385 did not.

Of 385 non-surgical eyes from 342 patients with diabetes (188 males, 156 females

and median age at diagnosis 73 years), 179 had VA measurements at diagnosis and

more than 6 weeks follow up. Of these the median VA at diagnosis was 0.40 LogMAR

(Snellen 8/20) (mean 0.56; range: -0.10 – NPL) including 8 eyes with CF, 2 with HM

and 1 with NPL. After a median follow up of 10.5 months (range: 6 weeks – 5.4 years)

the median VA was 0.46 LogMAR (Snellen 7/20) (mean 1.20) which included 8 eyes

with CF and 4 eyes with HM. Visual success was achieved by 11 eyes (6.2%; 95% CI:

3.5% to 10.7%).

Of 115 surgical eyes from 115 patients with diabetes (58 males, 57 females and

median age at diagnosis 73 years), a PPV was combined with ILM peel in 43 (37.4%),

epiretinal membrane peel in 45 (39.1%), retinopexy in 22 (19.1%), cataract surgery in

28 (24.4%) and a tamponading agent in 47 (40.9%) eyes.

Fourteen eyes experienced an intraoperative complication (10 iatrogenic tears and 4

iatrogenic retinal traumas’). Repeat VMT surgery was performed in 2 (1.7%) eyes, a

post VMT surgery macular hole operation was performed in 4 (3.5%), retinal

detachment in 1 (0.9%), other types of vitreoretinal surgery in 6 (5.2%) and cataract

surgery in 15 (13.0%) eyes.

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Fifty-five of the 155 surgical eyes from patients with diabetes had preoperative and

postoperative VA measurements as well as more than 6 weeks follow up. Of these

the median VA at surgery was 0.70 LogMAR (Snellen 4/20) (mean 0.76; range: 0.20 –

CF) including 2 eyes with CF. After a median follow up of 11.8 months (range: 6

weeks – 6.3 years) the median VA was 0.60 LogMAR (Snellen 5/20) (mean 0.70)

which included 1 eye with CF and 2 eyes with HM. Visual success was achieved by 16

eyes (29.1%; 95% CI: 18.8% to 42.1%).

DISCUSSION

This database study aimed to collect pragmatic clinical data on the management of

VMT. It found that many patients are managed conservatively, with relatively stable

VA over the short term. Those who undergo surgery obtain modest VA

improvements, with 12.6% having an intraoperative complication, most commonly

retinal breaks. The most frequent postoperative complications were cataract in

42.7% of eyes, retinal detachment in 2.7%, and macular hole in 2.2%.

A systematic review and meta-analysis of VMT surgery found that small, petechial,

self-resolving retinal hemorrhages were the most common intraoperative

complication (5.6% of eyes), followed by retinal breaks (1.6%).10 The present study

also found retinal breaks and retinal hemorrhage or trauma to be the most common

intraoperative complications, although the rates were higher and the order reversed

(8.0% and 2.9% respectively). The studies contributing to the systematic review may

be more subject to publication bias than our study, as surgeons may be reluctant to

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publish poor outcomes and journals may be more likely to publish novel

interventions that improve clinical outcomes.26 By contrast the present database

study selected routine cases pooled anonymously from a range of hospitals. In

addition, the EMR mandated data collection at the time of surgery, such that the

surgeon had to confirm whether or not a complication occurred. This, combined with

anonymised data collection, should encourage accurate reporting of surgical

complications and may explain the higher intraoperative complication rates in this

analysis, although it may not fully overcome an innate tendency to underreport

complications and the true complication rate could therefore be higher.

Whereas the surgical procedures and complication rates in this study are likely to be

reliable, the VA data were less complete and need to be interpreted with caution.

Nonetheless, the data suggest that VA was relatively stable in those patients

managed conservatively, at least over the median 10.8 months follow up period.

There are very few natural history studies, but Hikichi et al found that VA tended to

decline over the longer term, with almost two thirds of patients losing at least 2

Snellen lines over 5 years.11 It is possible our patients would show a similar decline if

follow up was longer. Also, patients whose VA did decline may have been more likely

to undergo surgery, and selectively exit our observation cohort. The limited VA data

support this assumption, as eyes that underwent surgery lost 0.04 logMAR units over

a median of 2.8 months prior to surgery, which extrapolates to a change from 20/54

to 20/80 in the year prior to surgery. Therefore, our non-surgical group may not fully

reflect the natural history of VMT.

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In those patients who did undergo surgery, median VA improved only modestly from

0.6 to 0.5 logMAR (20/80 to 20/63) over median follow up of 10.2 months, with only

36% gaining at least 0.3 LogMAR units (≈2 Snellen lines). This is similar to a value of

33% reported in a systematic review.10 Whilst VA is an accepted measure of visual

function, patients with VMT may benefit if surgery reduces their metamorphopsia,

and VA does not directly measure any such gain.

There was a greater than expected number of patients receiving intravitreal gas

injection. Gas may be selected for a variety of reasons including intraoperative

retinal breaks, pre-existing macular hole or concern that peeling of the ILM or ERM

might have caused a macular hole, to help seal sutureless sclerotomies, or perhaps

to help tamponade and flatten elevated macular tissue. It is likely that retinal breaks

were responsible for many cases as they were relatively common, whereas we

expect pre-existing macular holes to be a less frequent explanation, as these cases

are more likely to be coded as a macular hole than VMT, and air was the most

commonly used tamponade (air is seldom selected for the treatment of macular

holes).21

The rate of post-vitrectomy cataract surgery is less than might have been expected.

For example, a UK database study reported that 92% of phakic eyes required

cataract surgery within three years of vitrectomy undertaken for macular hole,21 with

an equivalent figure of 74% for RD.22 Whilst both macular hole and retinal

detachment require intravitreal tamponade, which is thought to increase lens

opacity,27 a database study of vitrectomy undertaken for a range of conditions also

reported a three year cataract surgery rate of 74%,23 suggesting that gas tamponade

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cannot fully explain the difference between the present analysis and others. Also,

many patients undergoing VMT surgery also received gas tamponade, albeit often

with short-acting gases. Although speculative, one explanation for the low cataract

rate in our study might be the relatively simple nature of VMT surgery. Another is

that those patients expected to require cataract surgery following vitrectomy, due to

preoperative subclinical lens opacity, were treated with combined phacovitrectomy,

which occurred in more than a quarter of eyes. In addition, our figures may include

some pseudophakic patients in the denominator, as pseudophakic patients who had

their cataract surgery recorded before the EMR was implemented may not have

been recognised as pseudophakic in the present analysis; hence the incidence of

cataract in phakic eyes may be somewhat higher than we report. We also had a

relatively high proportion of diabetic patients, and diabetes is known to reduce post-

vitrectomy cataract.28

Strengths of this study include pooled anonymized collection of pragmatic clinical

data from a range of hospitals, mandated intraoperative recording of complications,

and its large size relative to all prior publications on VMT. It is also the first database

study of VMT. Notwithstanding the advantages of randomised controlled trials for

testing new treatments, a database study may better reflect routine care, delivered

without the rigid eligibility criteria and mandated follow up of a clinical trial. As such

it may be more representative of usual care. The main weakness of this study relates

to incomplete data collection on VA change over time, and hence VA outcomes

should be considered exploratory. However, database studies seldom have full levels

of data completeness and their interpretation necessarily involves this consideration.

17

Future database studies might consider requesting sites to provide mandated

outpatient VA data collection, but until that occurs this study may help clinicians to

benchmark their surgical complication rate, and help patients consider the risks and

benefits of surgery.

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ACKNOWLEDGEMENTS

Collaborators: Vitreomacular Traction Study Group: Fiona Bishop, Ted Burton,

Ahmed El-Amir, Paul H.J. Donachie, Alan Fitt, Steven Harsum, Richard Haynes, Julian

Hickman-Casey, Timothy L. Jackson (Chair), Robert L. Johnston, Dominic McHugh,

Richard Newsom, Rubina Rahman, Martin Snead, Steve Winder, Yit Fung Yang, Rahila

Zakir, and Hadi Zambarakji.

The authors thank the following sites for contributing clinical data: Leeds Teaching

Hospitals NHS Trust; Norfolk and Norwich University Hospitals NHS Foundation

Trust; Royal Berkshire NHS Foundation Trust; Peterborough and Stamford Hospitals

NHS Foundation Trust; Epsom and St Helier University Hospitals NHS Trust;

University Hospitals Bristol NHS Foundation Trust; East Sussex Hospitals NHS Trust;

King’s College Hospital NHS Foundation Trust; Gloucestershire Hospitals NHS

Foundation Trust; University Hospital Southampton NHS Foundation Trust;

Calderdale and Huddersfield NHS Foundation Trust; Cambridge University Hospitals

NHS Foundation Trust; Sheffield Teaching Hospitals NHS Foundation Trust;

Portsmouth Hospitals NHS Trust; Imperial College Healthcare NHS Trust; Whipps

Cross University Hospital NHS Trust.

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22. Jackson TL, Donachie PH, Sallam A, Johnston RL. United Kingdom national ophthalmology database study of vitreoretinal surgery: report 3, retinal detachment. Ophthalmology. epub ahead of print.23. Jackson TL, Donachie PH, Sparrow JM, Johnston RL. United Kingdom National Ophthalmology Database Study of Vitreoretinal Surgery: Report 1; Case mix, complications, and cataract. Eye (Lond) 2013.24. Sparrow JM, Taylor H, Qureshi K, et al. The Cataract National Dataset electronic multi-centre audit of 55,567 operations: risk indicators for monocular visual acuity outcomes. Eye (Lond) 2012;26:821-6.25. Bryant T. Computer software for calculating confidence intervals. In: Altman DG, Machin D, Bryant TN, Gardner MJ, eds. Statistics with confidence, 2 ed. London: BMJ Books, 2000.26. Newcombe RG. Towards a reduction in publication bias. Br Med J (Clin Res Ed) 1987;295(6599):656-9.27. Thompson JT. The role of patient age and intraocular gases in cataract progression following vitrectomy for macular holes and epiretinal membranes. Trans Am Ophthalmol Soc 2003;101:485-98.28. Smiddy WE, Feuer W. Incidence of cataract extraction after diabetic vitrectomy. Retina 2004;24:574-81.

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FIGURE LEGENDS

Figure 1: Figure shows a Kaplan-Meier curve of the rate of post-vitrectomy cataract

surgery (PVCS), over time.

Figure 2: Figure shows the change in logarithm of the minimum angle of resolution

(LogMAR) visual acuity from baseline to final follow up, for those eyes undergoing

vitrectomy for vitreomacular traction (VMT). The size of each circle is proportional to

the number of patients in that category, with those above the dashed line of identity

demonstrating an improvement by at least 0.3 LogMAR units (approximately 2

Snellen lines). Of 160 cases, 71 improved by ≥ 0.3 units, 58 remained in the same

category, and 31 deteriorated by ≥0.3 units.

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