Deferral of surgery for epiretinal membranes: Is it safe? Results of a randomised controlled trial.

BACKGROUND/AIMS: To compare the visual outcome in early versus deferred surgery in patients with idiopathic epiretinal membrane (ERM) and good presenting visual acuity and mild symptoms. METHODS: This study is a randomised clinical trial. 53 eyes of 53 patients with symptomatic ERM and best-corrected visual acuity (BCVA) at presentation ≥65 early treatment diabetic retinopathy study (ETDRS) letters were randomised to immediate surgery (20 eyes) or to watchful waiting (33 eyes) for 1 year. Primary end-point was BCVA after 12 months. Secondary end-points were central macular thickness and the number of patients that crossed over from the watchful waiting arm to the surgery arm due to deteriorated symptoms. RESULTS: Mean BCVA after 12 months in the watchful waiting group (81 letters) were not significantly different from patients undergoing immediate surgery (82.5 letters, p=0.647). During 1 year of follow-up, eight patients in the watchful waiting group (24%) crossed over to surgery and these patients gained a mean of 3.1 letters (SEM 1.38). Patients randomised to immediate surgery gained approximately one line. Watchful waiting patients who remained without surgery were stable. The visual acuity gain after surgery is slow and gradual until 9 months postoperatively. There were no serious complications such as retinal detachment or infectious endophthalmitis. CONCLUSIONS: Vitrectomy for early symptomatic ERM is beneficial in preserving excellent vision. A watchful waiting approach with 1 year of follow-up is safe in the sense that this group does not lose five ETDRS letters in waiting. Deferral of surgery by regular monitoring of patients is a safe approach. TRIAL REGISTRATION NUMBERS: H-C-2008-026 and NCT00902629.

Do different spectral domain OCT hardwares measure the same? Comparison of retinal thickness using third-party software.

PURPOSE: Spectral-domain optical coherence tomographies (OCTs) from different companies do not give identical retinal thicknesses. The purpose of this study was to evaluate if differences in thickness when using a spectral domain Cirrus OCT or a Heidelberg Spectralis are due to hardware differences, or if they are caused by the segmentation algorithms. METHODS: Thirty-seven healthy eyes were examined within the same session with a Cirrus OCT and a Spectralis OCT, the latter using averaged B-scans. Scans from similar positions and passing the fovea were analyzed by custom-made software. Thickness was analyzed at the fovea, the central 1-mm line and the 6-mm line. RESULTS: When Cirrus and Spectralis scans were analyzed with the same software, the retinal thickness at the foveal center was 225.92 µm (SD 17.0) using the Cirrus and 228.70 µm (SD 18.4) using the Spectralis; the difference of 2.78 µm was not significant (p = 0.055). For the central 1 mm, the difference was 1.78 µm (p = 0.0414), and for all points out to 6 mm, the Spectralis retinal thickness was also significantly larger than the Cirrus thickness (p = 0.0052), though the mean difference was only 1.85 µm. Also for the RPE_OScomplex, Spectralis measured a greater thickness than did Cirrus, with a mean of 3.32 µm (p < 0.0001) for all points. CONCLUSION: The retinal thicknesses from the Cirrus and from the Spectralis differed by 14 µm with the standard software of the instruments, and by less than 3 µm when analyzed with the same custom-made software, indicating that the major differences between the two SD-OCT systems are due to differences in their built-in software algorithms.

Refractive change after vitrectomy for epiretinal membrane in pseudophakic eyes.

PURPOSE: To report the change in refraction in pseudophakic eyes following 23-gauge vitrectomy for epiretinal membrane (ERM), without use of silicone oil, intraocular gas or scleral buckling. METHODS: Retrospective review of the records of 28 pseudophakic eyes in 28 patients undergoing 23-gauge pars plana vitrectomy for ERM. All 28 eyes had a measured preoperative refraction in their records and were seen minimum 2 months after vitrectomy for measuring their refraction. Fellow eyes (28 eyes) were used as controls. RESULTS: The mean preoperative refraction was -0.15 ± 0.85 dioptre (D), and the mean postoperative refraction was -0.41 ± 0.93 D. Thus, a myopic shift was observed following vitrectomy with a mean change in refraction of -0.26 ± 0.60 D (range +0.75 to -2.13 D, p = 0.032). The postoperative change in refraction was within ±0.25, ±0.50 and ±1.00 D in 39%, 68% and 96% of the eyes, respectively. The mean absolute refractive error was 0.47 ± 0.44 D. The change in refraction in fellow eyes was +0.01 D (p = 0.82). CONCLUSION: The change in refraction following 23-gauge pars plana vitrectomy for ERM in pseudophakic eyes was -0.26 D.

Quantification of retinal tangential movement in epiretinal membranes.

OBJECTIVE: To describe a technique of quantifying retinal vessel movement in eyes with epiretinal membrane (ERM) and correlate the retinal vessel movement with changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), and patients' subjective reports about experienced symptoms (symptoms). DESIGN: Retrospective, observational, comparative case series. PARTICIPANTS: A total of 206 eyes of 113 patients: 142 eyes with ERM and 64 healthy fellow eyes. METHODS: All patients were examined as part of a screening protocol for a randomized clinical trial on ERM. Heidelberg Spectralis (Heidelberg Engineering Inc, Carlsbad, CA) optical coherence tomography (OCT) scanning had been performed twice or more in all patients. Eyes with ERM and healthy fellow eyes were examined. For each eye, the 2 fundus images were aligned using Heidelberg's AutoRescan feature. The macular area was divided into 9 subfields, and retinal vessel movements were calculated. For each eye, the total length of the 9 vectors was summed to describe the total retinal vessel movement (retinal tangential movement [RTM]). MAIN OUTCOME MEASURES: To quantify retinal vessel movements associated with ERM. The secondary outcome was to correlate measured retinal vessel movement with changes in BCVA, CMT, and patients' subjective symptoms. RESULTS: The study found significantly greater RTM in ERM eyes compared with healthy eyes (P<0.001). Among ERM eyes, the RTM was significantly greater in patients with worsening of symptoms compared with ERM eyes with unchanged assessment of symptoms. There were statistically significant correlations between increased RTM and reduction in BCVA (P = 0.024), increased CMT (P<0.001), and time between visits (P<0.001). CONCLUSIONS: This study showed that ERM is not a static retinal disease but a dynamic condition in which retinal vessel movement associated with ERM was measureable, even in patients who had stable BCVA and CMT. The retinal vessel movements correlated to worsening of BCVA and increased CMT, and were more pronounced in patients with worsening of symptoms.