The study was a retrospective, interventional case series of consecutive patients diagnosed with vitreomacular traction syndrome at the vitreoretinal service clinic of the Yonsei University Eye, and Ear, Nose, and Throat Hospital, Seoul, Korea. Six eyes of six patients were included. All six patients underwent a complete ophthalmic examination, including dilated fundus examination using an indirect ophthalmoscope and 90+ diopter noncontact lens slit lamp biomicroscopy. In addition to routine ophthalmic examination, OCT retinal mapping using third generation OCT (OCT3; instrument manufactured by Stratus Zeiss Humphrey, San Leandro, CA) was performed preoperatively on all patients, as previously described.17 The diagnosis of vitreomacular traction syndrome was made when apparent traction from the vitreous causing increased thickness of the macula was observed. Internal fixation was used and the scanning and video images were displayed simultaneously to verify fixation. Six consecutive radial scans 30 degrees apart were obtained with a 6-mm length, centering on the patient's fixation point. The mean central macular thickness was calculated using the Early Treatment for Diabetic Retinopathy Study (ETDRS) central 1mm zone area of the macula. With the six radially scanned images, three-dimensional configuration of vitreomacular adhesion was analogized and the farthest point of the detached posterior hyaloid membrane from the retinal surface was located. After the location of the posterior hyaloid opening site, pars plana vitrectomy was performed on all six patients.

Pars plana vitrectomy using 25-G Transconjunctival Sutureless Vitrectomy (TSV) system was performed. After the core vitrectomy, access to the subhyaloid space was made by creating an opening with a 25-G needle at the previously located site based on the OCT retinal mapping. The posterior hyaloid membrane was then peeled off with a micropick in a circular fashion around the fovea.

In patient 4, the located site was in the superotemporal area at the meridian of a 60 degree plane. Since the total scan length was 6 mm, the site might be between 2.5 and 3.0 mm apart from the foveal center. During the operation, we drew two imaginary circles, each the size of the optic nerve head (~1.5 mm in diameter), along the 60-degree plane and made an opening through the posterior hyaloid membrane within the second circle.The opening site was assumed to be about 2.5 mm away from the foveal center and corresponded to the preoperatively located site based on the OCT retinal mapping (Fig. 1). Then, the tractional posterior hyaloid membrane was peeled off as previously described (Fig. 2). The same surgical method was applied to all other patients.

Best corrected visual acuity and central macular thickness by OCT were measured before the operation and 3 months afterwards.

Statistical analyses utilized SPSS®12.0.1 (SPSS Inc., Chicago, IL) for Windows. Wilcoxon signed-rank tests were run to compare differences between follow-up and baseline data. The level of statistical significance was set at P<0.05.

The baseline characteristics are listed in Table 1. All six patients had symptoms of reduced visual acuity and four of them had metamorphopsia. One eye was pseudophakic at symptom onset but did not have a temporal relationship with cataract surgery, which suggested possible postoperative complications were causing the macular changes.

Based on the classification by McDonald and associates5, three of the patients were classified as the classic type, characterized by midperipheral posterior vitreous detachment with persistent attachment to the macula and optic disc. The other three eyes were variable types with one or more quadrants attached to the vitreous, in addition to vitreomacular traction. Three of them had cystoid macular changes, presumed to be due to tractional etiology, and all of the eyes revealed tractional macular detachment.

Pars plana vitrectomy with TSV 25-G system was performed on all six patients. Posterior hyaloid membrane attached to the posterior retina was released by previously described method. No intraoperative complications were observed.

Best corrected visual acuity significantlyimproved from 0.4 to 0.75 with mean increase by 3.5 lines on a Snellen chart (Wilcoxon signed-rank test, P=0.027). The mean preoperative foveal thickness was 406 µm and significantly decreased to 241 µm 3 months after the operation (P=0.027). The foveal pit was restored in five patients and one patient had a remaining diffuse thickening of the macula, although the foveal thickness was significantly decreased. No patients had any signs of persistent vitreomacular traction or postoperative complications during thefollow-up period.

Pars plana vitrectomy to release the tractional posterior hyaloid membrane has been the mainstay of the treatment for the vitreomacular traction syndrome.7-13 Several previous studies regarding the disorder reported excellent visual improvement after the operation.7-13

After the advent of OCT as an important diagnostic tool for the vitreomacular traction syndrome, a more precise understanding of the vitreoretinal attachment's configuration has become possible with additional images obtained by performing six consecutive radial scans 30 degrees apart with a 6 mm length centering on the patient's fixation point.14-19 In the current study, we used OCT retinal mapping to analogize the three-dimensional architecture of the vitreomacular adhesion and to select a safe access point into the subhyaloid space. With the OCT retinal mapping tomograms, making an access into the subhyaloid space could be conducted more safely and effectively at the site where the posterior vitreous detachment was farthest from the retinal surface. This technique is even more useful in variable types of the disorder with absence of vitreous separation in the midperiphery and localized perifoveal hyaloid detachment, which is shallow and invisible. All of these factors could make access to the subhyaloid space a technically challenging procedure using a conventional technique. After making an opening to the subhyaloid space, we peeled off the posterior hyaloid membrane by circumscribing it around the fovea through the opening site. By circumscribing the posterior hyaloid membrane, the traction on the macula during the procedure could be minimized. Regarding the surgical outcomes of the variant types, Yamada and associates20 previously reported that patients with V-shaped incomplete posterior vitreous detachment (classic type) responded more favorably after the operation than those with partial posterior vitreous detachment temporal to the fovea but attached nasally and developed into cystoid macular edema (variant type), which could lead to a macular hole or macular atrophy. However, Johnson21 reported excellent outcomes in variant vitreomacular traction syndrome by using the surgical technique of making an opening in the perifoveal hyaloid membrane and circumscribing the vitreous around the fovea to avoid traumatic separation. In the current study, we observed significant functional and anatomical improvement of vitreomacular traction syndrome regardless of disorder type. The visual outcomes were even better in variable types, with a postoperative visual acuity of 0.8 or better in all three patients.

In conclusion, OCT retinal mapping program is a valuable diagnostic tool in determining the configuration of the vitreomacular adhesion and planning the surgical approach during procedures for vitreomacular traction syndrome.