PPV with ILM peeling in post traumatic macular hole
Indications for consideration of the surgical management of macular holes are based on the presence of a full-thickness defect. Once this defect has developed, the potential for spontaneous resolution is low. Thus, surgical management is recommended with documentation of a stage 2 or higher, full-thickness macular hole. Stage 1 holes and lamellar holes are managed conservatively with observation at this time. See Controversies surrounding the surgical repair of macular holes.
Historically, therapy for macular holes has evolved from pharmacologic interventions, such as anxiolytics and vasodilators, to an assortment of surgical techniques, such as cerclage, scleral buckles, direct photocoagulation of the hole edges, and intraocular gas tamponade without the aid of vitrectomy. In 1982, Gonvers and Machemer were the first to recommend vitrectomy, intravitreal gas, and prone positioning for retinal detachments secondary to macular holes.
Kelly and Wendel reported that vision might be stabilized or even improved if it were possible to surgically relieve tangential traction on the macula, reduce the cystic changes, and reattach the cuff of detached retina surrounding the macular hole. They proposed that by performing this surgery, they could flatten the retina and possibly reduce the adjacent cystic retinal changes and neurosensory macular detachment.
In 1991, Kelly and Wendel demonstrated that vitrectomy, removal of cortical vitreous and epiretinal membranes, and strict face-down gas tamponade could successfully treat full-thickness macular holes. The overall results of their initial report were a 58% anatomic success rate and visual improvement of 2 or more lines in 42% of eyes. A succeeding report showed a 73% anatomic success rate and 55% of patients improving 2 or more lines of visual acuity. Present anatomic success rates range from 82-100% depending on the series.
A prospective, randomized, and controlled series by the Vitrectomy for Treatment of Macular Hole Study Group for stage 2, 3, and 4 holes showed that vision was improved in surgically treated eyes compared with observed eyes. However, more frequent adverse effects were observed in the surgically treated eyes compared to the control eyes, with the most common adverse effects being macular retinal pigment epithelium changes and cataractogenesis.
Some aspects of the surgery may vary, but the basic technique is the same. The anterior and middle vitreous is removed via a standard 3-port pars plana vitrectomy. Patients with macular hole frequently undergo vitrectomy using smaller gauge vitrectomy systems (ie, 25 gauge, 23 gauge). Associated instruments have been developed for these smaller gauge, transconjunctival vitrectomy systems.
The critical step appears to be the removal of the perimacular traction. Factors contributing to this traction, such as the posterior hyaloid, the ILM, and coexisting epimacular membranes, need to be addressed. The traction exerted by the posterior hyaloid on the macula should be relieved by either removing just the perimacular vitreous or combining it with the induction of a complete posterior vitreous detachment. Various surgical techniques have been described to accomplish this task, including the use of a soft-tipped silicon cannula or the vitrectomy cutter with the cutter disengaged. A “fish-strike sign” or bending of the silicon cannula has been described as a sign that the posterior hyaloid has been engaged. Then, it may be released from the underlying retina and removed with the vitrectomy cutter.
The removal of ILM is considered to be a contributing factor in the success of macular hole surgeries. ILM peeling may be accomplished via a “rhexis” not unlike that of a capsulorrhexis in lens surgeries. Very fine forceps may be used to peel the ILM from the underlying retina. Care should be taken not to include the deeper layers in the forceps’ grasp, which may further damage the surrounding retinal tissues. Currently, many surgeons use indocyanine green dye to stain the ILM making it easier to visualize and manipulate.
Epiretinal membranes, if present, also should be removed. Techniques in completing this procedure vary from surgeon to surgeon.
After careful indirect ophthalmoscopic examination of the peripheral retina for tears, a total air-fluid exchange is performed to desiccate the vitreous cavity. A nonexpansile concentration of a long-acting gas is exchanged for air. Studies have shown that a longer period of internal tamponade equated to a higher success rate.
Sterile air and varying concentrations of either perfluoropropane or sulfur hexafluoride have been used based on surgeon preference for internal tamponade. The primary difference achieved using different gases is the duration of the gas bubble and, consequently, the amount of internal tamponade achieved within the first several days after surgery. Silicone oil has also been used as an internal tamponade for patients with difficulty positioning or altitude restrictions. However, the use of silicone oil necessitates a second subsequent surgery to remove the oil. Furthermore, the visual results are not comparable to the use of gas tamponade, possibly as a result of silicone oil toxicity at the level of the photoreceptors and RPE.
Tafoya et al showed, at 1 year, a final postoperative visual acuity difference of 20/96 (LogMAR 0.208) for silicone oil eyes versus 20/44 (LogMAR 0.453) for gas treated eyes. Lai et al also showed the visual acuity advantage of gas tamponade with a smaller difference (20/70 vs 20/50). However, Lai et al also showed the rate of single operation closure being only 65% for silicone oil and 91% for gas tamponade.Thus, unless limited by patient circumstances, gas tamponade for macular hole repair is preferable to silicone oil tamponade.
Controversies surrounding the surgical repair of macular holes
20-gauge versus 23-gauge versus 25-gauge vitrectomy systems
While no one system poses a significant long-term advantage, smaller gauge vitrectomy systems, with frequently self-sealing wounds, avoid induced astigmatism from suturing sclerotomies, resulting in a more rapid recovery of vision.
An initial increase in endophthalmitis appears to have been addressed by changing the means of wound construction but may still be considered a disadvantage to small gauge vitrectomy systems.
Smaller gauge vitrectomy systems, especially 25-gauge systems, lack shaft stiffness because of the smaller barrel and also complicate the actual vitrectomy surgery for surgeons trained using 20-gauge systems.
Internal limiting membrane (ILM) peeling
ILM peeling increases the rate of hole closure 93-100%.
The rate of visual recovery was postulated to be slowed by ILM peeling, but no recent literature supports this assertion (see next bullet point).
Spiteri-Cornish et al compared peeling with not peeling ILM in a meta-analysis of 4 randomized controlled trials. The results demonstrated an effect favoring ILM peeling for macular hole closure and final visual acuity. The analysis did not identify any difference in the rate of recovery. The benefit of ILM peeling became evident even by 3 months postoperatively.
Use of vital dyes
Indocyanine green (ICG) dye was the first vital dye used for macular surgery. There is considerable literature questioning the toxicity of ICG dye to the retina and retinal pigment epithelium (RPE). Despite the laboratory science and literature cautioning the use of ICG dye, an equal amount of literature documented good surgical and visual results. ICG dye is still used by surgeons with care taken to limit the exposure of the retina and, potentially more importantly, the RPE to the dye.
Trypan blue has also been used to stain the ILM without the literature suggesting toxicity. On the other hand, trypan blue does not appear to stain the ILM as effectively as ICG dye.
Triamcinolone acetonide has also been used to facilitate peeling of the ILM. As of 2008, it is the only surgical adjunct to peeling of the ILM that is FDA approved for use in the eyes.
Management of lamellar holes
Lamellar holes cause symptoms but minimal loss of central visual acuity. Management has historically been conservative.
Surgical intervention has been undertaken with vision loss or patient symptomology with the recent advances in small gauge vitrectomy and further experience with ILM peeling.
Historically, strict face-down positioning had been recommended for patients for up to 4 weeks, with consequent difficulties of compliance and patient quality of life during that period.
More evaluation placed into shorter periods of face-down positioning, though, traditionally, it has been believed that the shorter the period of face-down positioning, the lower the rate of successful hole closure. In 1997, Tournambe et al described a pilot study of patients without face-down positioning. They reported a success rate with one surgery of 79% and suggested that pseudophakia was necessary for consideration of liberalization of positioning requirements.
The advent of ILM peeling has encouraged a second look at minimal to no face-down positioning. Rubinstein et al described a case series of 24 eyes of patients who underwent ILM peeling and then did not position postoperatively. In this case series, 22 eyes were successfully closed and had visual improvement with both eyes that failed being stage 4 large holes.
Others have reported comparable, if not better, results in patients with only 1 day of positioning. Dhawahir-Scala et al suggests that a critical factor is the size of the gas bubble on postoperative day 1 being greater than 70%. Tranos et al showed, however, that there may be more rapid progression of cataract formation with less face-down positioning.Tranos et al were among several authors who recommended combined phacovitrectomy for phakic patients to allow less stringent positioning requirements. Iezzi and Kapoor reported a series of 68 eyes that underwent macular hole repair with broad ILM peeling and SF6 tamponade without any face-down positioning. They reported a 100% rate of closure with a single procedure.
The use of pharmacologic adjuncts, such as a transforming growth factor-beta (TGF-beta) and autologous serum, to facilitate hole closure has not been proven to have any added benefit as compared to controls such that their use has not gained much popularity.