Diabetic macular edema is the leading cause of visual loss in patients with diabetic re­tino­pathy [1]. The most common therapeutic approach to treatment of the patients with an existing diabetic macular edema is laser pho­tocoagulation. Regarding the functional results, grid pattern laser photocoagulation in patients with diffuse macular edema showed limited efficacy in many staqes.The release of tractional forces is supposed to be the leading mechanism for the decrease of macular edema. Several authors reported on the resolution of diabetic macular edema after surgical removal of the posterior hyaloids [2–4].

Some authors [5–7] found that in many cases separation of the adhesions between the posterior hyaloid and the retina may lead to complications during the surgery (iatrogenic tears, bleeding). To avoid intrasurgical compli­ca­tions we performed a non-comparative pro­spective study in 30 eyes with chronic diabetic macular edema, with usage of perfluorooctane liquid for delamination of the adhesions between the membrane and the retina.

Materials and Methods

The consecutive interventional case series included 30 patients with diabetic chronic ma­cular edema, who underwent pars plana vitrec­tomy with removal of posterior hyaloid mem­brane. The preoperative information collected included age, sex, surgical eye, preoperative diagnosis, best corrected visual acuity, and lens status.16 female, 14 male with a mean age of 59 ((2) years were included. The mean duration of macular edema was 6 months. 23 (76,7%) patients suffered from diabetes type 2 , only 7 (23,3%) patients from diabetes type 1. 27 (90%) patients had a history of systemic hypertension. 19 (63,3%) patients had under­gone grid pattern laser photocoagulation before. 30 eyes (100%) were phakic. Fluorescein angiography was performed in 12 patients before surgery and 11 patients after surgery (Topcon TRC-50IX).

Optical coherence tomography (Zeiss STRATUS OCT) was done before and after surgery (in 3 months) for visualization of the vitreoretinal interface and identification of the eyes with diffuse macular edema that should benefit from surgery. Fundoscopic examination and the assessment of best-corrected visual acuity (BCVA) were performed pre- and post­ope­ra­tively. The mean duration of follow-up was 3 months.

Surgical Technique

After standard three-port pars plana vitrec­tomy (Storz Premier) and separation of posterior hyaloid face from the underlying retina intra­na­sa­ly to the optic disk (Fig. 1) delimination was carried out using infusion of perfluo­rooctane (Dk-line Perfluorodekalin, Bausch & Lomb) liquid between tough posterior hyaloid and un­der­lying retina using 20 gauge cannula attached to a syringe (Fig.2).

After that we performed removal of the separated posterior hyaloid and fibrovascular tissue from the underlying perfluorooctane bubble using vitrector. All the surgeries were done by one surgeon.

Case Reports

Case 1

The patient was a 59-year-old man, who was diagnosed with diabetic non-proliferative retinopathy, chronic macular edema with traction in the right eye. Pars plana vitrectomy with removal of the posterior hyaloid membrane with perfluorooctane usage was performed. No complications during the surgery were registered. Preoperative BCVA was 0,08. Preoperative macular thickness was 591(28 mkm. (Fig.3). After 6 months BCVA was 0,2 and macular thickness – 130(43 mkm. (Fig. 4).

Case 2

The patient was a 63-year-old woman who was diagnosed with diabetic non-proliferative retinopathy, chronic macular edema with traction, cataract 2 in the left eye. Lensvitrec­tomy with removal of the posterior hyaloid membrane with perfluorooctane usage, p/c IOL implantation was performed. No complications were registered during the surgery. Preoperative BCVA was 0,09 . Preoperative macular thickness was 695(0 mkm. (Fig. 5). After 5 months, BCVA was 0,3 and macular thickness –174(80 mkm. (Fig. 6).

Results and their discussion

The surgical procedure was successful in all eyes. OCT examination revealed decreased retinal thickening in 24 eyes (80%). In 9 eyes macular edema resolved completely. Only in 4 eyes (13,3%) macular edema was unchanged postoperatively. The mean BCVA improved from 0,09 ((0,008) to 0,2 ((0,002). Posto­pera­tive BCVA was significantly better than preoperative BCVA. 15 eyes (50%) gained at least two lines of visual acuity, and 4 eyes (13,3%) gained 4 lines or more. 2 eyes (6,7%) lost 1 line. 8 eyes (26,7%) had unchanged BCVA. Complications during surgery were: bleeding in 1 eye (3,3%), no iatrogenic tears and retinal detachments. Postoperative complications were noted in 7 eyes, which were managed conservatively. Transient ocular hypertension occured in 4 eyes (13,3%), preretinal blood in 3 eyes (10%).

We report our results after vitrectomy and removal of the posterior hyaloids in 30 eyes impaired by chronic diabetic macular edema within prospective study. Dissection of fibro­vas­cular proliferation and complete separation of non-vascularised postbasal vitreous cortex reduces postoperative rebleeding and recurrence of retinal detachment in proliferative diabetic retinopathy. The use of perfluorocarbon liquids in posterior segment surgery previously has been reported to be valuable for dissection of preretinal or epiretinal membranes [8,9]. The reported results are various. Perfluorocarbon liquid is colourless and odourless, has a high density and low viscosity. The intraoperative use of perfluorocarbon liquid in vitreoretinal surgery was introduced in 1987 by Chang for the treat­ment of giant retinal tears, retinal detachments with proliferative vitreoretinopathy (PVR), and traumatic retinal detachments [10].

In our study 22 eyes were with proliferative retinopathy, 8 eyes with non-proliferative retinopathy, 12 eyes with cataract 1, 8 eyes with cataract 2, and 2 eyes with cataract 3. 2 eyes have undergone lensvitrectomy with IOL implantation. We com­pa­red our data with results of the retrospective study Epiretinal membrane removal in diabetic eyes: comparison of viscodissection with conventional methods of membrane peeling [7]. In that study eighty nine eyes underwent standard three port pars plana vitrectomy, and membrane segmentation and delamination was carried out using traditional pick and scissors dissection with manually activated instruments.

Final best corrected visual acuity improved three or more Snellen lines in 28 eyes (48%), remained unchanged in 20 eyes (34.5%), and worsened in 10 eyes (17.5%), in comparison with our results 15 eyes (50%) gained at least two lines of visual acuity, while 4 eyes (13,3%) gained 4 lines or more. 2 eyes (6,7%) lost 1 line. 8 eyes (26,7%) had unchanged BCVA. Compli­ca­tions during the operation (iatrogenic retinal breaks) occurred in 10 eyes (11%) in the non-viscodissection group and in our results - bleeding in 1 eye (3,3%) , no iatrogenic retinal breaks.

Conclusion

Pars plana vitrectomy with removing post­e­ri­or hyaloid membrane reduced macular edema in most cases. Usage of perfluorooctane liquid for removal of tough posterior hyaloids allow to avoid intrasurgical complications.

References

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