Diabetes and Macular Degeneration are more treatable than ever.
By SUMIT RANDHIR SINGH, MD • JAY CHHABLANI, MD
March 1, 201751
Macular hole (MH) is defined as a full-thickness defect in the neurosensory retina at the fovea. The annual incidence is estimated to be 8.7 eyes per 100,000 population with a female preponderance as high as 3.3:1. The incidence has also been found to increase as patients age.1,2
The 3-port pars plana vitrectomy with internal limiting membrane (ILM) peeling with gas tamponade, described by Kelly and Wendel with modification by Eckardt et al, has been the standard of care for the past 2 decades. The success rate remains very high, exceeding 90%.3,4 However, in cases with larger-diameter macular holes, anatomical closure rate decreases dramatically. Using electron microspcopy, Schumann et al showed fibrocellular proliferations as a consequence of ILM remnants and residues of vitreous cortex collagen in all failed eyes after the first surgery.5 Ip et al reported a closure rate of 56% for MH of size ≥400 µm with poor visual outcome.6 Similarly, chronic, relapsed macular holes or holes associated with trauma are also found to have a poor closure rate with the conventional technique described above.7-9
Various innovative techniques have been described to achieve a good closure rate in these refractory cases, including the inverted ILM flap technique, the ILM free-flap technique, autologous lens capsular flap, autologous neurosensory retinal flap, arcuate retinotomy, and perifoveal radial incisions. Herein, we describe the various newer techniques, including the surgical challenges and outcomes.
Sumit Randhir Singh, MD, and Jay Chhablani, MD, practice at the L.V. Prasad Eye Institute in Hyderabad, India. Drs. Singh and Chhablani report no financial interests in products mentioned in this article. Dr. Chhablani can be reached via e-mail at firstname.lastname@example.org.
The inverted ILM flap technique was initially described by Michalewska et al.10 It involves placing small remnants of peeled ILM that are left attached to the hole margins on the macular hole upside down. Michalewska et al reported anatomical closure in 100% of cases with macular hole size ≥400 µm (excluding 7 cases of spontaneously detached ILM flap during trimming or fluid air exchange).10 Similarly, Khodani et al, in their study involving holes larger than 1,000 µm, reported type 1 closure in 4 out of 5 cases with the inverted ILM flap technique.11
Chakrabarti et al studied 26 eyes using an inverted ILM flap with the use of macular plug (autologous gluconated blood clumps) and achieved 100% hole closure with visual acuity improvement from 1 logMAR unit to 0.5 logMAR units. The excellent results were shown without any use of fluid air exchange, gas tamponade, or postoperative positioning.12
One recent modification to the inverted ILM flap technique is the use of an ILM hinge as described by Andrew et al.13Here, a small pedunculated flap is left attached to the margin of the hole and then flipped backward toward the base of the hole (Figure 1).13
The explained mechanism for closure is that Muller cell fragments in the remnants of ILM may induce gliosis and also promote tissue proliferation by acting as a scaffold that can reposition the photoreceptors in the vicinity of the fovea. Disinsertion of the flap from the hole margin or complete removal of the flap while trimming the flap with cutter are few of the known complications. Gentle manipulation of the flap and turning the infusion port off during flap inversion reduces fluid currents and maintains the flap in place. Trimming of the flap can also be done using scissors.
This technique has been described for cases in which ILM peeling has failed to achieve the desired anatomic outcome. However, this can be performed in primary ILM peeling surgeries as well. A free flap with a dimension similar to, or slightly larger than, the macular hole is recovered from the margin of previously peeled ILM. This is followed by placement of a low-molecular-weight viscoelastic over the flap and then fluid air exchange, thus protecting against any displacement of the flap.
Morizane et al reported hole closure in 90% (9 out of 10 eyes), with 80% of patients gaining visual acuity by 0.2 logMAR.14 The authors studied patients with idiopathic macular hole ≥400 µm in size with failed primary vitrectomy and secondary macular holes subsequent to failed vitrectomy with ILM removal for foveoschisis.
Displacement of the free flap can occur during fluid air exchange, and the flap can get displaced while floating in the viscoelastic. Slightly larger grafts, if used, can be easily tucked in the macular hole edges to prevent displacement. A representative case is shown in Figure 2.
Both the anterior and posterior lens capsule have been transplanted into the macular hole with good anatomical and functional results (0.2 logMAR improvement in 14 out of 20 eyes).15 The anterior capsule can be retrieved during combined procedures of phacoemulsification with vitrectomy and preserved in a balanced salt solution after staining with 0.125% ICG. It has greater specific gravity compared to the ILM flap, so after settling at the base of the hole, it is expected to have a lower dislocation rate. Similarly, posterior lens capsule can be harvested in pseudophakic eyes. The best closure rate was achieved with anterior lens capsule (100% in 10 eyes). However, the functional gain was not significantly different between the two groups.15 Advantages of this technique include lower dislocation rates and utility in cases with failed ILM peeling surgery where only minimal ILM is available as a graft.
A new technique described by Grewal and Mahmoud refractory myopic macular hole involves an endolaser applied to the area marked for graft harvesting, followed by diathermy to the blood vessels at the edge.16 A free retinal flap that is 0.5 disc diameter larger than the macular hole size is lifted and placed over the hole. This is followed by perfluoro-n-octane heavy liquid and then silicone oil exchange. The authors reported that the best corrected visual acuity improved from 20/200 preoperatively to 20/80 at 3 months along with improvement in mean retinal sensitivity in microperimetry. The mechanisms postulated leading to closure are the graft acting as a barrier for the vitreous thereby forming a macular plug and also acting as scaffold for proliferation of glial tissue.16
Separation of the retinal graft can be facilitated with a soft-tip cannula. Graft transportation to the macular hole can be eased by transportation under the heavy liquid. Displacement during fluid air exchange can be prevented by complete extrusion of fluid around the heavy liquid bubble and then bringing the heavy liquid bubble over the disc for removal. A representative case is shown in Figure 3.
Using a novel arcuate retinotomy technique, Charles et al evaluated 6 patients with failed primary macular hole surgeries.17 Five patients had anatomical closure (83%) and 3 patients had gain of visual acuity. The technique (Figure 4) uses 25-gauge curved scissors and incorporates a full-thickness temporal incision, thereby splitting the nerve fiber layer instead of cutting it. The retinal bridge is then displaced nasally using a soft-tip cannula to decrease the horizontal diameter of hole, changing it to a vertically oval shape.17
In one of the techniques described by Reis et al in patients with failed ILM peeling surgery, 5 perifoveal radial incisions are made using barbed MVR blade or a 25-gauge needle (Figure 5). The incisions are made full thickness, starting 1 hole diameter away from the hole margin and terminating at the margin of the hole. The nasally located papillomacular bundle is spared. The authors reported hole closure in all 7 patients with a gain in vision (mean lines score gain of 5.6).18In another modification by Shah et al in complex pediatric traumatic retinal holes, 2 full thickness radial retinal incisions are made nasally and temporally.19 The authors achieved anatomic success in both patients.
Various adjuncts have been used to facilitate hole closure, protect bare retinal pigment epithelium, and prevent subretinal migration of dye. Injection of autologous heparinized whole blood as a very thin film on the surface of the hole followed by injection of brilliant blue G dye (BBG) protects the retinal pigment epithelium and also has been thought to act as a biological glue. This was shown by Ghosh et al in a prospective study of 60 patients where these patients had inner segment/outer segment junction continuity in more eyes (P=.03) and better BCVA at 6 months (P=.04) compared to the group with standard BBG staining.20
Similarly, Watchlin et al have advocated injection of a single drop of autologous platelet concentrate (4 x 109thrombocytes/mL) into the hole after ILM peeling in pediatric patients with traumatic macular hole. In their study, all 4 patients achieved anatomic success and visual gain of 3 lines to 7 lines.21
The above-described techniques prove useful, especially for large and refractory macular holes, which in the past had poor surgical outcomes. These novel techniques reveal advancement in surgical techniques with better anatomic outcomes. However, the long-term functional outcomes are yet to be analyzed. RP
Retinal Physician, Volume: 14, Issue: March 2017, page(s): 44-46, 48
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