Kang Yeun Pak

Perfluoro-n-octane Assisted Free Internal Limiting Membrane Flap Technique for Recurrent Macular Hole.

Perfluoro-n-octane Assisted Free Internal Limiting Membrane Flap Technique for Recurrent Macular Hole Vitrectomy combined with removal of the internal limiting membrane (ILM) and gas tamponade is considered a standard procedure for macular hole. Hole closure is not sufficient for the recovery of vision but is necessary to ensure good visual acuity and prevent further vision loss. It is challenging to achieve hole closure in cases of chronic large macular holes or in highly myopic eyes. Recently, various surgical techniques using the ILM have been introduced to improve the surgical outcomes in such cases. The inverted ILM flap technique, first described by Michalewska et al, has shown improved functional and anatomical outcomes. Our group has reported a similar technique, whereby the macular hole is covered with a singlelayered ILM flap using perfluoro-n-octane (PFO) to stabilize the flap during fluid–air exchange. However, these procedures are not feasible in cases where the ILM around the macular hole has already been removed, such as cases of recurrent macular hole or failed surgery. Herein, the authors describe a modified technique for covering a recurrent macular hole with a free flap of the ILM with the assistance of PFO.

TOPOGRAPHIC CHANGES OF THE MACULA AFTER CLOSURE OF IDIOPATHIC MACULAR HOLE.

Purpose: To investigate retinal displacement in the macula after surgical closure of idiopathic macular hole and to identify factors correlated with displacement. Methods: This retrospective multicenter study included 73 eyes of 73 patients having idiopathic macular hole. A custom program was developed to compare the position of the retinal vessels in the macula between preoperative and postoperative photographs. En face images of a 6 mm × 6 mm optical coherence tomography volume scans were registered to calculate the scale. A grid comprising 16 sectors in 2 rings (inner; 2–4 mm and outer; 4–6 mm) was superimposed. The displacement of the retinal vessels was measured as a vector value by comparing the location of the retinal vessels in each sector. The correlation between displacement and various clinical parameters was analyzed. Results: The average displacement was 57.2 &mgr;m at an angle of −3.3° (nasal and slightly inferior). Displacement was larger in the inner ring (79.2 &mgr;m) than in the outer ring (35.3 &mgr;m, P < 0.001), and larger in the temporal sectors than in the corresponding nasal sectors (P ⩽ 0.008). Inferior and superior displacement was noted in the superior and inferior sectors, respectively. Multiple regression analysis revealed that basal horizontal macular hole diameter and size of internal limiting membrane removal were independent factors of displacement. Conclusion: The macula was displaced centripetally, nasally, and slightly inferiorly after surgical closure of idiopathic macular hole. Hole closure, contraction of the nerve fiber layer, and gravity are the suggested mechanisms of macular displacement caused by internal limiting membrane peeling.

Intravitreal pharmacokinetics after posterior subtenon triamcinolone acetonide injection in vitrectomized rabbit eyes.

Purpose: To investigate the intraocular pharmacokinetics of triamcinolone acetonide (TA) injected into the posterior subtenon of vitrectomized rabbit eyes. Methods: Vitrectomy was performed on the right eyes of 35 rabbits. Triamcinolone acetonide (40 mg/mL) was injected into the posterior subtenon space of both eyes. Five rabbits each were killed at days 1, 3, 7, 14, 28, 56, and 84. Both eyes were enucleated. The vitreous was isolated, and TA concentration was measured. Results: In vitrectomized eyes, the intravitreal concentrations of TA were 1763, 822.9, 321.5, 113.3, 35.5, 14.4, and 6.7 ng/mL, respectively, at the time points indicated above; the concentrations in nonvitrectomized eyes were 397.8, 360.4, 154.4, 48.5, 30.7, 15.2, and 8.0 ng/mL, respectively. Triamcinolone acetonide concentrations were significantly higher in the vitrectomized eyes at days 1, 3, 7, and 14. The terminal half-life of intravitreal TA was 23.3 days in the vitrectomized eyes and 28.9 days in the nonvitrectomized eyes. Conclusion: Intravitreal absorption and excretion of TA in the posterior subtenon space are increased after vitrectomy. Although the terminal half-life of TA was shorter, higher early concentration and similar effective duration were achieved in the vitrectomized eyes.

ASSOCIATION BETWEEN TANGENTIAL CONTRACTION AND EARLY VISION LOSS IN IDIOPATHIC EPIRETINAL MEMBRANE.

Purpose: To investigate the clinical features associated with early visual loss in patients with idiopathic epiretinal membrane. Methods: Patients with idiopathic epiretinal membrane with visual acuity of ≥20/40, intact ellipsoid zone, and follow-up duration of at least 24 months were included in this retrospective age-matched control study. The disk–fovea–vascular (DFV) distance, central macular thickness, membrane configuration, and ellipsoid zone were assessed using fundus photography and spectral domain optical coherence tomography. Results: We analyzed the progression group (n = 15; vision loss ≥2 lines because of membrane progression) and the control group (n = 30; age matched). Compared with the controls, the mean DFV distance decreased (P < 0.001), central macular thickness increased (P = 0.017), and the ratio of the follow-up and baseline DFV distances (traction index of membrane) was significantly lower (P = 0.001) in the progression group. No differences were observed in the follow-up membrane configuration and ellipsoid zone. Factors associated with early vision loss were the DFV distance change (&rgr; = 0.657; P = 0.008) and traction index of membrane (&rgr; = −0.636; P = 0.011). Their area under receiver-operating characteristic curves were significant (DFV distant change: 0.915, traction index of membrane: 0.910, respectively; P < 0.001, both). Conclusion: Assessing the DFV distance is useful in quantifying the tangential contraction of macula and the prediction of vision loss in idiopathic epiretinal membrane.

Efficacy of the Perfluoro-N-Octane-Assisted Single-Layered Inverted Internal Limiting Membrane Flap Technique for Large Macular Holes

Purpose: The aim of this study was to evaluate the efficacy of the perfluoro-n-octane-assisted single-layered inverted internal limiting membrane (ILM) flap for large macular holes (MHs). Methods: We reviewed idiopathic MHs >400 μm. The patients were divided into ILM peeling (group P, 51 eyes) and ILM flap (group F, 41 eyes). Closure of MHs, best-corrected visual acuity (BCVA), and postoperative optical coherence tomography findings were analyzed. Results: MH closure was achieved in 88.2% in group P and in 100% in group F (p = 0.032). SF6 and air was used most frequently in groups P and F, respectively. Both had a significant improvement in BCVA, which was better in group F until 3 months, but not at 6 months. At 6 months, the ellipsoid zone and external limiting membrane were restored with no significant difference. Conclusion: The single-layered inverted ILM flap was better for the closure of large MHs than ILM peeling, without using long-acting gas that prevents early rehabilitation.

TREAT-AND-EXTEND REGIMEN USING RANIBIZUMAB FOR POLYPOIDAL CHOROIDAL VASCULOPATHY: One-Year Results.

Purpose: To investigate the efficacy of a treat-and-extend regimen (TER) using ranibizumab to treat polypoidal choroidal vasculopathy (PCV). Methods: We retrospectively reviewed the medical records of 29 patients with PCV, who had been treated with a TER for 1 year. The primary outcome was the proportion of eyes that did not lose ≥3 best-corrected visual acuity (BCVA) lines. The number of intravitreal injections and recurrences as well as the maximum treatment interval without recurrence were analyzed. Results: The mean BCVA improved from 0.64 ± 0.42 logMAR (median, 20/80) at baseline to 0.30 ± 0.31 logMAR (median, 20/30) at 12 months (P < 0.001). The mean central subfield macular thickness improved from 307.0 ± 70.2 &mgr;m to 237.5 ± 64.4 &mgr;m (P < 0.001). None of the subjects lost ≥3 lines, and 15 (51.7%) gained ≥3 lines. The mean number of injections was 7.0. The mean maximum treatment interval without recurrence was 10.0 weeks. After the loading phase, 12 eyes (41.4%) showed no recurrence. Seven eyes (24.1%) demonstrated disease activity at 12 months, and 4 (13.8%) of them were never dry during the entire 12-month follow-up duration. Conclusion: The TER effectively improved visual acuity in PCV while reducing the number of injections.

Functional end-arterial circulation of the choroid assessed by using fat embolism and electric circuit simulation

The discrepancy in the choroidal circulation between anatomy and function has remained unsolved for several decades. Postmortem cast studies revealed extensive anastomotic channels, but angiographic studies indicated end-arterial circulation. We carried out experimental fat embolism in cats and electric circuit simulation. Perfusion defects were observed in two categories. In the scatter perfusion defects suggesting an embolism at the terminal arterioles, fluorescein dye filled the non-perfused lobule slowly from the adjacent perfused lobule. In the segmental perfusion defects suggesting occlusion of the posterior ciliary arteries, the hypofluorescent segment became perfused by spontaneous resolution of the embolism without subsequent smaller infarction. The angiographic findings could be simulated with an electric circuit. Although electric currents flowed to the disconnected lobule, the level was very low compared with that of the connected ones. The choroid appeared to be composed of multiple sectors with no anastomosis to other sectors, but to have its own anastomotic arterioles in each sector. Blood flows through the continuous choriocapillaris bed in an end-arterial nature functionally to follow a pressure gradient due to the drainage through the collector venule.

Exclusive Use of Air as Gas Tamponade in Rhegmatogenous Retinal Detachment

Purpose To investigate outcomes of vitrectomy for rhegmatogenous retinal detachment (RRD) using air exclusively as the gas tamponade. Methods This retrospective, interventional, consecutive case series involved reviewing medical records of patients that underwent vitrectomy and gas tamponade for RRD between January 2013 and December 2015. Patients whose eyes were treated exclusively with air tamponade since July 2014 were assigned to the air group, while those treated with heterogeneous gas agents before June 2014 were assigned to the control group. The primary outcome was the primary reattachment rate. Best-corrected visual acuity (BCVA) and duration to detect redetachments were assigned as the secondary outcomes. Results The air group and the control group included 71 and 72 eyes, respectively. The primary reattachment rate was 94.4% in the air group and there was no significant difference with 94.4% in the control group (p = 0.951). BCVA was significantly better in the air group at 1 month (p = 0.021) but not at 3 months postoperatively (p = 0.561). Redetachments were recognized earlier in the air group (9.3 ± 0.5 days) compared with those in the control group (21.3 ± 7.4 days) (p = 0.041). Conclusions In cases of simple RRD with sufficient removal of subretinal fluid, air could be considered for use as gas tamponade. This trial is registered with KCT0002358.

Comparison of vitrectomized with nonvitrectomized eyes after subtenon injection of triamcinolone acetonide to treat diabetic macular edema: Retrospective comparative Analysis of an interventional case series

Purpose: Triamcinolone acetonide (TA) is an alternative option for diabetic macular edema thanks to its cost-benefit ratio and unique delivery route. We performed this study to compare vitrectomized with nonvitrectomized eyes treated with subtenon TA injection for diabetic macular edema. Materials and Methods: We retrospectively reviewed the medical records of patients who had undergone subtenon TA injection for diabetic macular edema treatment. The patients were divided into two groups: Vitrectomized and nonvitrectomized. Visual acuity and central subfield macular thickness (CSMT) were analyzed before injection, at 1 and 3 months after injection. Results: Visual acuity in vitrectomized group improved significantly at 1 month (P = 0.002), but this improvement regressed after 3 months. In the nonvitrectomized group, visual acuity did not improve significantly after 1 month, but it did after 3 months (P = 0.019). The CSMT decreased significantly in both groups at 1 and 3 months (P < 0.001). There were no significant differences between the groups at either 1 or 3 months with regard to either visual improvement or change in CSMT. Conclusion: Subtenon TA injection could be an alternative treatment option for diabetic macular edema, both in vitrectomized and in nonvitrectomized eyes. TA seems to take effect earlier and decay faster in vitrectomized eyes.