Congenital optic nerve head pits affect fewer than one person in a population of 10,0001 and are found to be bilateral in 10% to 15% of cases, whereas 25% to 75% of cases with optic disc pit develop serous macular detachment2–3 and retinoschisis within the second to fourth decades of life. There is no consensus regarding the indications for surgical intervention or the methods and techniques of surgery. Multiple surgical techniques have been described for persisting optic disc pit maculopathy (ODPM),4–7 but not one of the techniques has been proven to be better than the others. Moreover, surgical dilemma increases many-fold in the case of an unusual presentation. We report our experience with one such case of ODPM who presented with rapid progressive loss of vision and a large outer retinal defect at the macula, wherein autologous internal limiting membrane (ILM) “chunk” transplantation was additionally performed along with vitrectomy and ILM peeling. To the best of our knowledge, this is the first reported instance of ILM “chunk” transplantation and subsequent microstructural outer retinal regeneration analysis using adaptive optics technology in an unusual presentation of optic disc pit associated maculopathy.
A 38-year-old male patient presented to us with rapidly progressive diminution of vision in the right eye for 3 months. On examination, his best-corrected visual acuity (BCVA) was noted as counting fingers at 2 meters, N36, as compared to 6/9, N6, 3 months previously.
Informed consent was obtained. Dilated fundus examination of the right eye confirmed the presence of optic disc pit and associated maculopathy. On spectral-domain optical coherence tomography (SD-OCT) (Spectralis HRA-2; Heidelberg Engineering, Heidelberg, Germany), macular schisis was noted with an exceptionally large outer macular defect along with a thin tissue of inner layer bridging the defect (Figure 1A). In view of this rare presentation, we decided to perform an additional step of ILM “chunk” transplantation along with 25-gauge vitrectomy, ILM peeling, and gas endotamponade. ILM peeling was performed under perfluorocarbon liquid (PFCL) cover so that the peeled ILM formed a solid condensed “chunk” rather than a free-floating flap. It was followed by a nick in the inner retinal layer cap at the retinal defect edge with the help of “pic” forceps with subsequent transfer of ILM “chunk” into the subfoveal retinal defect with the help of soft silicone tip (Figures 2A–2D).
Spectral-domain optical coherence tomography of the right eye demonstrating (A) macular schisis and a large subfoveal outer retinal defect (base and minimum diameter of the outer retinal defect were 1,020 μm and 680 μm, respectively) with a thin inner layer cap. Subsequent autologous internal limiting membrane “chunk” transplantation resulted in (B) regeneration of the external limiting membrane and ellipsoid and interdigitation zones, along with bridging of the outer retinal layer deficiency.
Intraoperative fundus photographs demonstrating different steps of the surgery. (A) Triamcinolone-assisted posterior vitreous detachment induction is being performed. Optic disc pit (red arrow) and a large subfoveal outer retinal defect (green arrow) are clearly visible. (B) Brilliant blue-assisted internal limiting membrane (ILM) peeling (see red arrow) is being performed under perfluorocarbon liquid cover. Peeled ILM is in a single piece. (C) Condensed single-piece ILM “chunk” (red arrow) can be appreciated, which is (D) placed over the foveal defect (red arrow) and subsequently translocated beneath the inner retinal cap with the help of soft silicon tip.
Visual acuity subsequently improved to 6/18, N8, 3 months postoperatively. There was significant macular functional correction with reliable fixation stability (P1 and P2 being 61% and 90%, respectively, on 4–2 strategy) as measured on microperimetry (Maia; CenterVue, Fremont, CA) (Figure 3A). Outer retinal layer imaging on SD-OCT demonstrated regeneration of the external limiting membrane, as well as the ellipsoid and interdigitation zones in the subfoveal region with bridging of outer retinal layer defect (Figure 1B). No change in retinal pigment epithelial band architecture was observed which was found to be intact before and after surgery till the last follow up. Furthermore, adaptive optics imaging (RTX1; Imagine Eyes, Orsay, France) was performed in an area of 2 degrees × 2 degrees around the fovea (Figure 3). Significant active cone regeneration was detected at multiple sites (Figure 3, yellow arrows) with active cone concentration at points 1, 2, 3, 4, 5, 6, and 7 being 13,756/mm2, 14,672/mm2, 12,121/mm2, 13,245/mm2, 12,567/mm2, 13,572/mm2, and 14,232/mm2, respectively. Anatomical and functional improvement was sustained with further improvement in BCVA to 6/12, N8, at the last follow-up at 6 months postoperatively.
(A) Microperimetry chart (4–2 protocol) of the right eye with 0% fixation loss, reduced but reliable fixation stability (P1 and P2 being 61% and 90%, respectively), and preferred retinal locus' average threshold of 26 dB. (B) Adaptive optics image of the fovea (2° × 2°) demonstrating active cone regeneration at multiple sites (yellow arrows) with a black patch (red arrow), which corresponded to the internal limiting membrane “chunk” visible on spectral-domain optical coherence tomography (SD-OCT) in the subfoveal space (Figure 1B). Surrounding cloudy artifact (green arrow) corresponds to the persistent cystic spaces on the SD-OCT image in Figure 1B.
Multiple interventions have been proposed for the treatment of ODPM, but none has been established as the treatment of choice.
Laser photocoagulation at the temporal disc margin has been proposed,2 but the time for improvement is variable and often long.3 Pneumatic displacement has been proposed to cause reattachment of the macula,4 whereas Lie et al.5 proposed that combination of intravitreal gas injection and laser photocoagulation can result in complete resolution of intraretinal and subretinal fluid. Another proposed approach is macular-buckling surgery. Theodossiadis6 demonstrated complete resolution of fluid in about 85% of cases with significant improvement in visual acuity and visual fields in his case series post macular buckling. However, it should be noted that the surgical technique is cumbersome and has not gained popularity for the same reason. In the current scenario, the most popular approach for the treatment of ODPM is pars plana vitrectomy (PPV). It has been proposed that induction of complete posterior vitreous detachment (PVD) is essential to relieve traction required to achieve macular reattachment.7 García-Arumí et al.8 and Hirakata et al.9 reported good anatomical outcomes with the technique. Shukla et al.,10 on the other hand, advocated ILM peeling along with PPV and PVD induction in cases with ODPM and achieved complete resolution in six of their seven patients, with five achieving final visual acuity of 20/30 or better.
The current case was treated with peripapillary laser and intravitreal gas injection elsewhere with subsequent reported drop in vision. Serial OCT scans taken elsewhere demonstrated continuous increase in horizontal dehiscence of outer retinal layers at the macula during the 2-month period so much so that the base and minimum diameter of the outer retinal defect were 1,020 μm and 680 μm, respectively, at presentation (Figure 1A). This large disruption in outer retinal layers at the fovea was ascertained to be the most probable cause of severe and rapid visual loss in the right eye. Complete loss of external limiting membrane, as well as the ellipsoid and interdigitation zones, was noted along with progressive increase in dimension of schitic cavities. Traditionally, authors manage these cases with vitrectomy including triamcinolone-assisted PVD induction, ILM peeling, and gas endotamponade. But owing to the presence of a large outer retinal layer defect and lack of enough bridging tissue to plug the gap, authors contemplated to perform additional autologous ILM “chunk” transplantation to provide a scaffold for the retinal tissue to grow over. Since this is a different approach that was adopted by us in view of an aggressive presentation, detailed gross and microstructural outcome analysis was performed, which confirmed satisfactory positive outcome of the surgery, the most important of which was continuous active cone regeneration, which was demonstrated using adaptive optics technology. It primarily employs a deformable mirror which alters its shape corresponding to the wavefront of light reflected from the patient's eye. This improves the resolution of image (2 μm) captured by the instrument equipped with adaptive optics technology. Cone regeneration correlated perfectly with improved fixation stability on microperimetry.
To conclude, autologous ILM “chunk” transplantation adds a new dimension to the already existing techniques, especially in a challenging case of ODPM with large subfoveal outer retinal layer defect and gross functional loss.
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