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Long-term visual acuity and the duration of macular detachment: findings from a prospective population-based study
  1. Danny Mitry1,2,
  2. Muhammad Amer Awan3,
  3. Shyamanga Borooah1,
  4. Andreas Syrogiannis4,
  5. Charles Lim-Fat5,
  6. Harry Campbell2,
  7. Alan F Wright1,
  8. Brian W Fleck1,2,
  9. David G Charteris6,
  10. David Yorston3,
  11. Jaswinder Singh1
  1. 1Department of Ophthalmology, Princess Alexandra Eye Pavilion, Edinburgh, UK
  2. 2Department of Public Health Sciences, University of Edinburgh, Teviot Place, UK
  3. 3Department of Vitreoretinal surgery, Gartnavel General Hospital, Glasgow, UK
  4. 4Department of Ophthalmology, Ninewells Hospital, Dundee, UK
  5. 5Department of Ophthalmology, Raigmore General Hospital, Inverness, UK
  6. 6Department of Vitreoretinal surgery, Moorfields Eye Hospital, London, UK
  1. Correspondence to Dr Danny Mitry, Department of Ophthalmology and Public Health Sciences, University of Edinburgh, Teviot Place, Edinburgh EH3 9HA, UK.; mitryd{at}gmail.com

Abstract

Aim To report the long-term visual outcome of a multicentre prospectively recruited cohort of macula-off rhegmatogenous retinal detachments (RRD)

Methods The Scottish retinal detachment study was a prospectively recruited study that recruited all incident cases of primary RRD in Scotland over a 2-year period (2007–2009). All patients with a macula-off RRD from four participating sites were invited for clinical examination at 6 weeks, 3 months, 6 months and 1 year after the initial surgery. Using a joinpoint model we estimated the effect of duration of macular detachment on final visual outcome.

Results In total, there were 291 patients with macula-off RRD without pre-existing retinal disease who had successful repair after one operation. 65.9% achieved a final visual acuity (VA) of 0.48 logMAR(6/18). Our model identified two time points (day 8 (95% CI 3 to 15 days) and (day 21 (95% CI 6 to 26 days)) after which there was a statistically significant worsening in final VA.

Conclusions Our study suggests that the majority of patients with macula-off RRD successfully repaired with one operation will achieve a VA of 6/18 or better at final follow-up. After 8 days of macular detachment, the final visual outcome may be adversely affected and, thus, operative repair within this period is desirable. Duration of macular detachment of ≤8 days demonstrated a continuing improvement in VA for up to 1 year, a finding which was not found in macula detachments of longer duration.

  • Retina
  • Epidemiology
  • Vision
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Introduction

In the UK, the annual incidence of rhegmatogenous retinal detachment (RRD) is approximately 12 per 100 000 population, with nearly 60% of individuals presenting after the macula is affected.1 ,2 After macular detachment, improvement of central vision remains compromised with a large variation in visual outcome reported.3 In addition, the time of optimal surgical intervention remains inconclusive with some reports suggesting a delay worsens the visual outcome,4 ,5 others suggesting that after 1 week of the macula being detached, further delay should not be expected to have a significant effect on final visual outcome.6

There are very few studies in the UK that have reported long-term visual outcomes from a well characterised cohort of primary RRD. Based on the Scottish retinal detachment study, we present 1 year follow-up data for recruited individuals with a macula-off RRD, highlighting the influence of the duration of macular detachment on the final visual outcome.

Methods

The Scottish retinal detachment study was a 2 year prospectively recruited population-based study that successfully developed a comprehensive demographic and clinical database of incident cases of primary RRD over a 2 year period from the six vitreoretinal treatment sites in Scotland. The methodology and inclusion criteria have been described in detail previously.7 In this follow-up study, individuals diagnosed with a macula-off RRD at presentation from four surgical sites (Edinburgh, Glasgow, Dundee and Inverness) were examined at four time intervals after surgical repair. (6 weeks, 3 months, 6 months and 1 year) Data was collected on the duration of detachment, best corrected visual acuity (VA), and the presence of visually significant cataract. VA measurements were recorded using Snellen notation and were converted to −logMAR for statistical analysis.8

Incomplete data was defined as individuals who had less than two follow-up observations. Duration of macular detachment was defined as the time between onset of symptoms of macular detachment (sudden significant visual loss) and surgery. The type of detachment was classified as bullous, or shallow, by the operating consultant surgeon. Individuals with incomplete data were excluded, as were individuals with vitreous haemorrhage causing reduced vision, previous retinal or macular pathology, those with multiple RRD operations, those with silicone oil in situ and those with visually significant cataract. Using a joinpoint regression analysis (http://surveillance.cancer.gov/joinpoint/) we modelled the cumulative mean VA for each postoperative visit as a function of days of macular detachment to identify temporal periods statistically associated with an adverse visual outcome. We stratified our data according to the results of the model estimate, and performed an analysis of variance with the Tukey correction for multiple comparison to maintain an overall type I error rate of 0.05.

Statistical analysis was performed using Minitab v16 and R V.2.10.1. The study adhered to the tenets of the Declaration of Helsinki, and was approved by the multicentre research and ethics committee Scotland (MREC-06/MRE00/19).

Results

In total, 586 individuals with macula-off RRD were recruited across the four study sites as part of the Scottish retinal detachment study. After exclusion of participants with incomplete data (n=196) and those with previous retinal or macular pathology (n=57), multiple RRD repair (n=16), those with long-term silicone oil in situ (n=5), those with vitreous haemorrhage (n=10) and those with visually significant cataract (n=11), there remained 291 patients with primary macula-off RRD with no pre-existing retinal disease that had successful repair after one operation. Table 1 illustrates the similarities and differences in baseline characteristics between included and excluded participants. The groups were similar, with the exception of a higher proportion of vitrectomy as primary repair in the included participants (∼10%).

Table 1

Baseline demographics and clinical characteristics between included and excluded participants

The type of primary repair was: scleral buckle only in 19.2% (56/291), pars plana vitrectomy (PPV) only in 76.6% (223/291) and both scleral buckle and PPV in 4.1% (12/291). Approximately 74% (n=215) were phakic at the time of repair, and 23% (n=66) were pseudophakic. One year after PPV, approximately 14% (n=33) of phakic individuals also had cataract surgery. There was no significant difference in final VA at 1 year between this group (mean(SD) logMAR: 0.72 (0.5)) and the group that did not have cataract surgery in the first year after PPV (mean (SD) logMAR: 0.62 (0.58); p=0.13) suggesting that postoperative development of cataract was an insignificant confounder in the reported results.

Overall, 53.6% (n=156) had an improvement of at least 0.1 logMAR units between the first and final follow-up, with 65.9% (n=192) achieving a final VA of 0.48 logMAR (6/18). The overall mean (sd) preoperative VA was 1.71 (1.72). For phakic RRD it was 1.74 (1.02), and for pseudophakic RRD it was 1.61 (1.05). The overall mean VA increased from 0.87 logMAR at 6 weeks to 0.57 logMAR at 1 year (n=190), with a significant temporal trend (p<0.001) (figure 1). Approximately 10% (n=30) of individuals had a worse final VA. The principal attributed reason for a worse final VA in these cases comprised macular retinal folds (n=2), macular hole (n=6) and epiretinal membrane (n=22).

Figure 1

The mean and 95% CI of the logMAR visual acuity at the four follow-up time intervals. Pairwise comparison demonstrated a statistically significant improvement up to month 3.

The median number of days over which the macula was detached were 5 (IQR 2–14). Figure 2 illustrates the cumulative mean VA for each postoperative visit as a function of the days of macular detachment using a joinpoint regression estimate. Overall, the data demonstrated an almost linear trend relationship between final cumulative mean VA and days of macular detachment (χ2=5.69, p=0.016). The joinpoint model defined two time points (day 8 (95% CI 3 to 15 days) and (day 21 (95% CI 6 to 26 days)), after which there was a statistically significant worsening in final VA. Overall, 64% (n=186) of individuals had a macula-off RRD for less than or equal to 8 days, and only 38 individuals had a macula-off RRD of >21 days. A significantly greater proportion of individuals with a macular detachment of ≤8 days were phakic compared with those of >8 days duration, while macular detachments of >8 days were more commonly shallow macular detachments. (see table 2)

Table 2

Baseline comparison of demographic and clinical features in macula-affected RRD of different duration

Figure 2

Cumulative mean of the best-corrected postoperative visual acuity for each postoperative visit (6 weeks, 3 months, 6 months and 1 year) as a function of duration of macular detachment in days for all patients.

Figure 3 illustrates the mean VA at each visit stratified by duration of macular detachment. Macula-affected RRD of ≤8 days demonstrated a significant continuing improvement in VA for each pairwise postoperative visit up to month 3, with an overall significant trend towards continuing visual gain up to 1 year. Individuals with the macula detached for over 8 days demonstrated a significant improvement in VA at the first postoperative visit (6 weeks) with no significant improvement thereafter.

Figure 3

Analysis of variance with correction for multiple testing (α=0.05) demonstrated a significant improvement in mean visual acuity at 6 weeks and 3 months in the ≤8 days detached group with an overall trend towards visual gain up to 12 months. (p<0.001) The >8 days detached group did not demonstrate a significant visual improvement after 6 weeks.

Discussion

The Scottish Retinal Detachment Study was one of the largest prospectively recruited studies of primary RRD worldwide, providing an invaluable resource to study the natural history of RRD. In this study, we report the 1 year visual outcome of 291 individuals with macula-off RRD without previous macular or retinal pathology who had a successful retinal reattachment after one operation. Findings from this study highlight important features in relation to visual outcome of macula-off RRD that should be interpreted in light of several limitations. First, a significant proportion of individuals were excluded due to less than two follow-up visits, and data was collected in four of six potential recruitment sites. However, the recruitment sites each demonstrated a similar loss to follow-up rate, and these four sites accounted for 85% (1020/1202) of participants in the Scottish retinal detachment study. In addition, baseline demographics between included and excluded participants were very similar, thus we feel the data presented is an appropriately representative group.

The majority of cases of macula-off RRD presented in this study had a PPV as the mode of primary repair (76.6%). Overall, two-thirds of individuals with a macula-off RRD achieved a final VA of 6/18 or better at final follow-up. Previous long-term studies of macula-off RRD have primarily reported outcomes after scleral buckling, where a final outcome of 6/12 or better can be achieved in between 37% and 70%.3 ,4 ,9 Recent long-term outcome studies reporting PPV for macula-off RRD are limited, but have suggested a comparable visual outcome.10

In our study, the duration of macular detachment had a significant effect on final visual outcome. Specifically, our data demonstrates a strong linear relationship between final cumulative mean VA and days of macular detachment. Using a loglinear joinpoint regression estimate to model our data, we identified day 8 and day 21 after onset of macular detachment symptoms as important time periods, after which final visual outcome becomes adversely affected. We could not perform additional analysis of macula-off RRD of >21 days due to insufficient sample size in this group. Macula-off RRD of ≤8 days demonstrated a significant improvement in VA at each follow-up visit with a trend that continues for up to 1 year after postoperative repair suggesting that early surgical intervention may be beneficial for long-term visual outcome. For macula-off RRD of >8 days duration, the improvement in VA was no longer statistically significant after the first postoperative visit. Interestingly, macula-off RRD of >8 days were more likely to have had cataract surgery, and more often presented with a shallow macular detachment, features which are likely to influence the longer time to presentation in this group. Functional optical coherence tomography studies after RRD repair have demonstrated that disruption of the photoreceptor inner segment/outer segment (IS/OS) junction, a finding observed only in macula-off RRD correlates significantly with visual function up to 6 months postoperatively.11 ,12 Longstanding macula-off RRD may be more likely to demonstrate a persistent disruption of the IS/OS junction after surgical repair. Our findings suggest that the longer the macula is detached the worse the final visual outcome, but also that a longer duration of detachment reduces the potential for long-term visual gain. There is justification for operating on cases before the macula has been detached for 8 days to achieve optimal visual outcome. Previous studies have suggested for optimal outcome, and the macula-off duration should be no longer than 1 week prior to scleral buckle repair.6 ,13

Our study suggests that the majority of patients with macula-off RRD successfully repaired with one operation will achieve a VA of 6/18 or better at final follow-up. Data from this study suggests that after 8 days of macular detachment, the final visual outcome may be adversely affected, and thus, operative repair within this period is desirable. Duration of macular detachment of ≤8 days demonstrated a continuing improvement in VA for up to 1 year, a finding which was not evident in macula detachments of >8 days duration.

Acknowledgments

The authors acknowledge (a proportion of their) financial support from the Department of Health through the award made by the National Institute for Health Research to Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, for a Specialist Biomedical Research Centre for Ophthalmology. The views expressed in this publication are those of the authors and not necessarily those of the Department of Health.

References

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Footnotes

  • Meeting presentations British and Eire Association of Vitreoretinal Specialists, (BEAVRS), Kent, 2011 Association for Research and Vision in Ophthalmology (ARVO), Ft Lauderdale, 2012.

  • Contributors DM, wrote the manuscript and analysed the data. MAA, compiled the data and reviewed the manuscript. SB, AS and CL-F, organised, compiled and collected the data. AW and BWF, revised the manuscript and were involved in study design. DGC, DY and JS, provided senior supervision, reviewed the manuscript, provided statistical advice and were responsible for study design.

  • Competing interests None.

  • Financial disclosures This work was supported by a grant from the W.H. Ross Foundation for the Prevention of Blindness, The Royal College of Surgeons Edinburgh/Royal Blind Asylum/Scottish War Blinded and the Chief Scientist Office Scotland (CZB/4/705).

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

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