Hyung Bin Lim

Changes in corneal endothelial cell density and the cumulative risk of corneal decompensation after Ahmed glaucoma valve implantation

Aims To evaluate changes in the corneal endothelial cell density (ECD) and corneal decompensation following Ahmed glaucoma valve (AGV) implantation. Methods This study was retrospective and observational case series. Patients with refractory glaucoma who underwent AGV implantation and were followed >5 years were consecutively enrolled. We reviewed the medical records, including the results of central corneal specular microscopy. Of the 127 enrolled patients, the annual change in ECD (%) was determined using linear regression for 72 eyes evaluated at least four times using serial specular microscopic examination and compared with 31 control eyes (fellow glaucomatous eyes under medical treatment). The main outcome measures were cumulative risk of corneal decompensation and differences in the ECD loss rates between subjects and controls. Results The mean follow-up after AGV implantation was 43.1 months. There were no cases of postoperative tube–corneal touch. The cumulative risk of corneal decompensation was 3.3%, 5 years after AGV implantation. There was a more rapid loss of ECD in the 72 subject eyes compared with the 31 controls (−7.0% and −0.1%/year, respectively; p<0.001). However, the rate of loss decreased over time and statistical significance compared with control eyes disappeared after 2 years postoperatively: −10.7% from baseline to 1 year (p<0.01), −7.0% from 1 year to 2 years (p=0.037), −4.2% from 2 years to 3 years (p=0.230) and −2.7% from 3 years to the final follow-up (p=0.111). Conclusions In case of uncomplicated AGV implantation, the cumulative risk of corneal decompensation was 3.3%, 5 years after the operation. The ECD loss was statistically greater in eyes with AGV than in control eyes without AGV, but the difference was significant only up to 2 years post surgery.

Influence of Biometric Variables on Refractive Outcomes after Cataract Surgery in Angle-closure Glaucoma Patients

Purpose To evaluate the influence of biometric variables on refractive outcomes after cataract surgery in angle-closure glaucoma (ACG) patients. Methods In this case-control study, 42 ACG patients, 40 open-angle glaucoma (OAG) patients, and 35 controls without glaucoma who had undergone conventional cataract surgery were enrolled consecutively. Electronic medical records, including preoperative biometric variables (keratometric diopter, axial length, anterior chamber depth, and lens thickness), the refractive change (RC), and the absolute value of refractive change (ARC) were reviewed. Results In the control and OAG patients, the anterior chamber depth was negatively correlated with the ARC (r = -0.344, p = 0.043 and r = -0.431, p = 0.006, respectively), whereas there was no correlation in the ACG patients. Lens thickness was positively correlated with the RC, but not with the ARC, in the control and OAG groups (r = 0.391, p = 0.020 and r = 0.501, p = 0.001, respectively). In contrast, lens thickness in the ACG group was not correlated with the RC but was positively correlated with the ARC (r = 0.331, p = 0.032). Conclusions In contrast with the anterior chamber depth, preoperatively measured lens thickness may be a useful predictor of the direction of the RC after cataract surgery in control and OAG patients. However, in ACG patients, a thicker lens was correlated with a larger RC, regardless of the direction of the shift (hyperopic or myopic).

The Importance of Signal Strength in Quantitative Assessment of Retinal Vessel Density Using Optical Coherence Tomography Angiography

The quality of the scan image is important in microvascular circulation analysis using optical coherence tomography (OCTA). We aimed to investigate the effect of signal strength (SS) on OCTA metrics and minimum SS level that could be considered optimal. Macular 6 × 6 mm angiography images were acquired, and all subjects were divided into four groups according to the SS (SS 7, SS 8, SS 9, and SS 10) of the OCTA image. Vessel density (VD), perfusion density (PD), and foveal avascular zone (FAZ) metrics of the superficial capillary plexus were compared. In total, 446 eyes from young healthy subjects were included. As the SS increased from 7 to 10, the VD and PD of the total area, and the FAZ area increased significantly (all, p < 0.001), but there were no significant difference between SS 9 and SS 10 in all metrics. Correlation analysis between the SS and each parameter showed a high correlation coefficient (VD, r = 0.668; PD, r = 0.671; FAZ area, r = 0.570; all, p < 0.001). The measurements of VD, PD, and FAZ using OCTA varied significantly with the SS, and at least 9 of SS is recommended. The physician should be careful in the analyses of OCTA measurements showing different values of the SS.

Learning Curve for Endoscopic Endonasal Dacryocystorhinostomy

Purpose To elucidate the learning curve for endoscopic endonasal dacryocystorhinostomy (EE-DCR) based on the results of EE-DCR performed by three surgeons at three different tertiary hospitals. Methods A retrospective review of the medical records of 386 eyes of 337 patients who had undergone EE-DCR by three surgeons at three tertiary hospitals and who were available for a >6-month postoperative observation period was conducted. The success of a given surgery was determined based on the results of a test performed during the patients last outpatient visit to the hospital. The learning curve was identified by dividing the patients into four groups (20, 30, 40, and 50 eyes in each respective group) and comparing their success rates. Results The overall success rate of the entire study population was 86.3%. The success rates for each of three surgeons was 83.3%, 85.6%, and 88.1%, respectively. After dividing the patients into groups of 30 eyes each, all three surgeons showed a significant increase in surgery success rates after their first group of 30 eyes (p < 0.05). The overall success rate excluding the first 30 eyes was 92.9%, and all three surgeons exhibited a significantly improved success rate of >90% (A, 94.4%; B, 90.8%; C, 95.4%). Conclusions A surgeon should be required to perform at least 30 EE-DCR procedures to obtain stable surgical skill for this procedure.