Sungmin Hyung

Effect of Excision of Avascular Bleb and Advancement of Adjacent Conjunctiva for Treatment of Hypotony

Purpose To evaluate the efficacy of excision of avascular bleb and advancement of adjacent conjunctiva (EBAC) for treatment of hypotony after trabeculectomy with mitomycin C (MMC). Methods Fifteen patients (17 eyes) who received EBAC for correction of hypotony between September 1996 and October 2008 were reviewed retrospectively. The main outcomes were intraocular pressure (IOP) and postoperative complications. Results Hypotony (IOP <6 mmHg) of eight eyes (47.1%, seven patients) was caused by bleb perforation. Of these, two eyes (two patients) had a history of trauma. Hypotony appeared at 33.9±30.8 months, and EBAC was performed at 48.2±35.3 months after trabeculectomy with MMC. The mean follow-up period was 38.3±29.8 months. The qualified success rate of EBAC was 100% at 51 months after EBAC, and the complete success rate of EBAC was 76.5% at six months and 70.6% at 51 months, as determined by Kaplan-Meier analysis. Post-EBAC complications included blepharoptosis in four eyes (23.5%) and bleb perforation in one (5.9%). The blepharoptosis resolved within one month after EBAC in two patients. However, in the other patients, mild blepharoptosis remained at 17 and 22 months postoperatively. Conclusions EBAC was found to be an effective method for treatment of hypotony after trabeculectomy with MMC, and postoperative blepharoptosis was a major complication.

Effect of Gravity Acceleration on Choroidal and Retinal Nerve Fiber Layer Thickness: A Swept-Source Optical Coherence Tomography Study

Purpose The purpose of this study was to evaluate the effect of gravity acceleration on choroidal and retinal nerve fiber layer (RNFL) thickness using swept-source optical coherence tomography (SS-OCT). Methods Thirteen healthy volunteers who planned to participate in human centrifuge training as part of the flight surgeon selection process enrolled this study. During centrifuge training, gravity was gradually increased up to six times that of sea level. All subjects underwent complete ophthalmologic examination and three-dimensional wide-scanning SS-OCT imaging (DRI OCT-1 Atlantis; Topcon, Tokyo, Japan). Imaging was performed before (baseline), immediately after, and 15, 30, and 60 minutes after centrifuge training. Changes in choroidal thickness, choroidal volume, retinal thickness, and RNFL thickness after centrifuge training were analyzed. Results Mean choroidal thickness significantly and transiently decreased immediately (258.19 ± 73.54 μm, P < 0.001), 15 minutes (258.54 ± 75.12 μm, P = 0.001), and 30 minutes (254.31 ± 66.92, P = 0.001) after human centrifuge training, relative to baseline (273.35 ± 80.80 μm). However, the decreased choroidal thickness returned to baseline levels 1 hour after centrifuge training (270.12 ± 71.69 μm, P = 0.437). Mean retinal thickness and RNFL thickness were not significantly affected by human centrifuge training. In participants who suffered from gravity-force induced loss of consciousness (G-LOC) during training, the amount of the choroidal thickness decrease was larger than in participants who did not experience G-LOC. However, because of the small sample size, the difference, although large, was not statistically significant. Conclusions Choroidal thickness and volume significantly and transiently decreased after human centrifuge training, which might reflect that choroidal perfusion was transiently decreased during human centrifuge training. Considering choroidal thickness decreased after human centrifuge training, long-term exposure to a high gravity environment may lead to ischemic injury to ocular structures.

Changes of Accommodative Power in Vitrectomized Eyes with Crystalline Lenses.

Purpose To evaluate changes of accommodative power in phakic eyes after uneventful pars plana vitrectomy (PPV) in patients aged younger than 45 years without presbyopia. Methods We investigated patients aged younger than 45 years who underwent PPV without crystalline lens extraction because of vitreoretinal disorders. Twelve weeks after vitrectomy, the near point of accommodation, high-frequency component of accommodative microfluctuation, axial length, and anterior chamber depth of vitrectomized and contralateral nonvitrectomized eyes were examined. Results Ten eyes of 10 patients were included. The average patient age was 39.8 (±4.3) years. None experienced cataract progression in the vitrectomized eye up to 12 weeks after surgery. Near point of accommodation was significantly lower in the vitrectomized eye than in the opposite eye at 12 weeks after vitrectomy (5.23 [±1.39] diopters vs. 5.91 [±1.83] diopters, p < 0.001). The high-frequency components in the vitrectomized eyes were significantly greater than those in the contralateral eyes (p = 0.01). However, anterior chamber depth and axial length were similar in value to the preoperative observations. Conclusions Uneventful PPV in relatively young patients without presbyopia reduced accommodative power during the early postoperative period with no cataract progression.