Sungsoon Hwang

Microvascular Compromise Develops Following Nerve Fiber Layer Damage in Normal-tension Glaucoma Without Choroidal Vasculature Involvement

Purpose: To investigate capillary densities in patients with unilateral normal-tension glaucoma (NTG) and normal controls using optical coherence tomography-angiography. Materials and Methods: We recruited 13 patients with unilateral NTG and 13 healthy controls. Optical coherence tomography-angiography was performed and pure peripapillary retinal capillary density was calculated after manually excluding large vessels and the optic disc. Paired comparison of capillary densities was performed among 3 categories of eye: NTG eye, fellow eye, and normal eye. Through vascular layer stratification we investigated differences in the retinal and choroidal circulation. Results: In total, 33 eyes of 11 unilateral NTG patients and 11 controls were analyzed. Capillary densities of NTG eyes were significantly lower than those of fellow eyes or control eyes (both P=0.013). No significant differences were found between fellow eyes and control eyes (P=0.328). Area of capillary compromise was identical to the area of retinal nerve fiber layer (RNFL) defect in all 11 eyes. In layer analysis, a decrease in capillary plexus was demonstrated only in the inner retina and no definite changes were found in the outer retina and choroid. Optic nerve head microvasculature did not show areas of capillary dropout. Conclusions: In patients with unilateral NTG, we could observe significant retinal capillary compromise in the area of RNFL defect. No changes were demonstrated in the choroid and optic disc area. We speculated on a possibility of secondary microvascular changes in the retina to nerve damage from the wedge-shaped but not geographic shaped capillary compromise corresponding to RNFL defect area. Further studies on the optic nerve head microvasculature and blood flow are warranted to assess their relationship to glaucoma pathogenesis.

A comparison of visual outcome and rotational stability of two types of toric implantable collamer lenses (TICL) : V4 versus V4c

Purpose To compare the efficacy and rotational stability after implantation of two types of toric implantable collamer lenses (Toric ICL™(TICL);V4 and V4c, STAAR Surgical Co.) Study design Retrospective case series. Methods This retrospective study evaluated total 48 eyes of 48 patients who underwent the implantation with V4 and V4c TICL with a central hole; A twenty-four eyes of 24 patients with V4 TICL and 24 eyes of 24 patients with V4c TICL with a central hole. Visual acuity, manifest refraction, and intraocular pressure were evaluated before and after surgery. Rotational stability (disparity between the intended axis and achieved axis) was assessed in both groups using digital anterior segment photographs, and vector analysis was also performed. Results Uncorrected visual acuity improved in both groups without significant difference (P = .111). There were no statistical differences between two groups in postoperative SE and cylindrical errors (P = .067 and .384, respectively). The mean value of rotation was 4.17±3.31° and 3.39±2.36° in the V4 and V4c TICL groups, respectively without significant difference (P = .364). Vector analysis of astigmatic correction showed no significant diffrence between two groups. Conclusion V4 and V4c TICL have similar efficacy with regard to visual acuity and refractive outcomes and rotational stability.

Heritability of the morphology of optic nerve head and surrounding structures: The Healthy Twin Study

Background Optic nerve head (ONH) and surrounding structures such as β-zone peripapillary atrophy (PPA) are important structures in glaucomatous pathogenesis. Thus, for understanding genetic components in glaucoma pathogenesis, it is necessary to evaluate the heritability of ONH and surrounding structures. The present study investigated the genetic influences on ONH and surrounding structures such as β-zone PPA and retinal vessels. Methods A total of 1,205 adult twins and their family members (362 monozygotic (MZ) twin subjects (181 pairs), 64 dizygotic (DZ) twin subjects (32 pairs), and 779 singletons from 261 families), were part of the Korean Healthy Twin Study. ONH parameters including the vertical cup-to-disc ratio, the presence, the area and the location of β-zone PPA and the angular location of retinal vein were measured. The genetic influences on the structures were evaluated using variance-component methods. Results The intraclass correlation coefficient (ICC) values of axial length were highest among the parameters. The ICCs of the area and location of PPA were similar to those of vertical cup-to-disc ratio. However, retinal vessel angular locations showed low ICC values even in MZ twins. After age and sex adjustment, for axial length, vertical cup-to-disc ratio, the presence, area and location of PPA, the estimated narrow-sense heritability was 0.85, 0.48, 0.76, 0.50 and 0.65 in the right eye and 0.84, 0.47, 0.72, 0.46 and 0.72 in the left eye, respectively. The estimated narrow-sense heritability of angular location of the superior and inferior vein was 0.17 and 0.12 in the right eye and 0.13 and 0.05 in the left eye, respectively. Conclusions ONH and surrounding structures such as vertical cup-to-disc ratio and the presence, the area and the location of β-zone PPA seemed to be determined by the substantial genetic influence, whereas the venous angular location did not.

Comparison of astigmatism prediction error taken with the Pentacam measurements, Baylor nomogram, and Barrett formula for toric intraocular lens implantation

BackgroundTo evaluate and compare the astigmatism prediction errors taken with the Pentacam measurements, Baylor nomogram, and Barrett formula for toric intraocular lens (IOL) implantation.MethodsPhacoemulsification with toric Precizon IOL implantation was performed in 41 eyes with corneal astigmatism (range, 1 to 5 diopters (D)) determined by IOLMaster and SimK on Pentacam. Preoperative corneal astigmatism measurements were obtained from IOLMaster readings (IOLMaster, Baylor-IOLMaster, and Barrett-IOLMaster) and Pentacam readings (SimK, Baylor-SimK, Barrett-SimK, wavefront, true net power, total corneal refractive power, and vector derived by manual vector summation using corneal front and back astigmatism). Prediction error and intraclass correlation coefficient (ICC) between the measured (or calculated) astigmatism by IOLMaster and Pentacam and the estimated corneal astigmatism estimated by IOL toricity power and residual astigmatism were determined.ResultsThe centroid errors in prediction error with IOLMaster, SimK, Baylor-IOLMaster, Baylor-SimK, Barrett-IOLMaster, Barrett-SimK, wavefront, true net power, total corneal refractive power, and vector were 0.59@103, 0.61 @103, 0.37@161, 0.41@162, 0.24@171, 0.36@162, 0.42@106, 0.04@8, 0.07@82, and 0.03@82, respectively, in with-the-rule (WTR) astigmatism eyes at postoperative 3-month. They were 0.22@87, 0.20@74, 0.16@21, 0.54@10, 0.43@3, 0.33@19, 0.51@25, 0.31@58, 0.29@50, and 0.14@50 in against-the-rule (ATR) astigmatism eyes. Of the ten modalities, vector showed the lowest WTR astigmatism prediction error and the highest ICC between the predicted and the estimated corneal astigmatism for both WTR and ATR eyes.ConclusionVector summation using anterior and posterior corneal surface power taken with the Pentacam yields the least astigmatism prediction error and is a promising tool for determining toric IOL cylinder power.

Measurable Range of Subfoveal Choroidal Thickness With Conventional Spectral Domain Optical Coherence Tomography

Purpose We investigate the measurable range of subfoveal choroidal thickness (SFCT) with conventional spectral domain optical coherence tomography (SD-OCT) in normal healthy eyes. Methods All subjects underwent an SD-OCT horizontal line scan centered at the fovea with standard and enhanced depth imaging (EDI) techniques. Two independent observers manually measured SFCT on standard and EDI-OCT images, if two choroidal borders were identified. The rate of successful measurement with standard OCT was evaluated. Inter- and intraclass correlation coefficients and Bland-Altman plots were used for analysis. Results OCT images of 724 normal healthy eyes from 374 subjects were evaluated. Although the inner choroidal border was identified on all OCT images, the outer choroidal border was identified on 378 of 724 (52.2%) conventional OCT images. Mean SFCT of all study eyes measured by EDI-OCT images was 292.6 ± 94.0. The number of successful measurements with conventional OCT was 100%, 87.5%, 48.1%, 33.0%, and 0%, in the SFCT ranges of <241, 241–280, 281–320, 321–360, and >360 μm, respectively. The accumulated rate of successful measurement with conventional OCT was 100%, 96.4%, and 82.2% in the SFCT ranges of ≤240, ≤280, and ≤320 μm, respectively. Two protocols showed good inter-correlation of SFCT, when SFCT were measurable in both scans. Conclusions SFCT can be measured by conventional OCT in eyes with thin choroid, and the measured value shows high agreement with those measured by EDI-OCT. In such eyes, conventional OCT can be used potentially to evaluate the retina and choroid. Translational Relevance In eyes with a thin choroid, conventional OCT can be used potentially to evaluate the retina and choroid with high agreement with EDI-OCT.

Myopic Shift after Implantation of a Novel Diffractive Trifocal Intraocular Lens in Korean Eyes

Purpose To evaluate the clinical outcomes of cataract surgery using novel diffractive trifocal intraocular lenses (IOLs) in Koreans. Methods This was a retrospective, consecutive, interventional study of cataract surgery using POD FineVision IOL implantation. Complete ophthalmologic examinations were performed preoperatively and postoperatively. Defocus curves were assessed over a range of +1.5 to −4.0 diopters in 0.5-diopter steps at one month postoperatively. Uncorrected distant visual acuity, uncorrected intermediate visual acuity, uncorrected near visual acuity, corrected distant visual acuity, distant-corrected intermediate visual acuity, and distant-corrected near visual acuity were assessed one month postoperatively, and manifest refraction was performed during every visit. Results The study analyzed 31 eyes in 20 patients. There were statistically significant improvements in uncorrected distance visual acuity, uncorrected intermediate visual acuity, uncorrected near visual acuity, corrected distance visual acuity, distance-corrected intermediate visual acuity, and distance-corrected near visual acuity (p < 0.001). The final postoperative refractive outcomes showed statistically significant myopic shifts compared to the target refraction based on SRK/T, SRK-II, Haigis, and Hoffer Q formulas (p < 0.001). Conclusions POD FineVision IOLs provide stable visual restoration with improvements of near and intermediate vision in presbyopic eyes. POD FineVision IOLs show myopic shift in a Korean population; therefore, surgeons should be cautious when selecting IOL power in such patients.

Temporary Piggyback Intraocular Lens Implantation Versus Single Intraocular Lens Implantation in Congenital Cataracts: Long-Term Clinical Outcomes

Purpose To report the long-term results of temporary piggyback IOL implantation in congenital cataract and to compare the clinical outcomes of temporary piggyback IOL with those of single IOL implantation. Methods This is a retrospective, comparative, interventional study. The medical records of all consecutive patients who underwent cataract extraction and single or temporary piggyback IOL implantation within the first 3 years of life from 1999 to 2013 at Samsung Medical Center were reviewed. Twenty-eight eyes from 18 patients underwent single IOL implantation (monopseudophakia group), and 32 eyes of 20 patients underwent temporary piggyback IOL implantation in congenital cataract surgery (polypseudophakia group). Results The mean age at initial cataract surgery was 15.8 months in the monopseudophakia group and 11.1 months in the polypseudophakia group (P = 0.144). The average follow-up duration was 133 months in the monopseudophakia group and 120 months in the polypseudophakia group (P = 0.391). The best-corrected visual acuity at the last visit was 0.36 logMAR in the monopseudophakia group and 0.55 logMAR in the polypseudophakia group (P = 0.044). Four (14%) and 14 (44%) reoperations for complications within the anterior segment were performed in the monopseudophakia group and polypseudophakia group, respectively (P = 0.042). Four cases (14.3%) in the monopseudophakia group and 13 cases (40.6%) in the polypseudophakia group had a glaucoma-related adverse event (P = 0.086). Conclusions Compared with primary single IOL implantation in congenital cataract, temporary piggyback IOL implantation produced worse visual acuity, higher reoperation rate, and higher risk of secondary glaucoma. Temporary piggyback IOL implantation does not have benefit in congenital cataract.