The effect of various factors on variability of retinal nerve fiber layer thickness measurements using optical coherence tomography.

PURPOSE: To evaluate the effects of various factors on the variability of retinal nerve fiber layer (RNFL) thickness measurements using the Stratus optical coherence tomography (OCT) in normal and glaucomatous eyes. METHODS: Four hundred seventy-four subjects (103 normal eyes and 371 glaucomatous eyes) were scanned to determine the RNFL thickness measurements using the Stratus OCT. Measurements were obtained twice during the same day. The standard deviation (SD) was used to compare the variability in RNFL thickness measurements of the normal subjects to that of the glaucomatous patients. Multivariate regression analysis was used to evaluate which covariates were independent predictors of SD in overall mean RNFL thickness. RESULTS: The mean SD of all RNFL thickness measurements was larger in the glaucoma group except in one sector. In the multivariate regression analysis, the average signal strength (SS) and the relative SS change (difference in SS between initial and repeat scans, divided by initial SS) were independent predictors of the SD in the RNFL thickness measurements (partial R(2) = 0.018, 0.013; p = 0.016, 0.040, respectively). CONCLUSIONS: Glaucomatous eyes tend to be more variable than normal eyes in RNFL thickness measurement using the Straus OCT. The average SS and the relative SS changes appear to correlate with the variability in RNFL thickness measurement. Therefore, the results of the RNFL analysis should not be interpreted independently of these factors.

Retinal vessel caliber and risk factors for branch retinal vein occlusion.

PURPOSE: To describe the association between retinal vessel caliber and risk factors for branch retinal vein occlusion (BRVO). MATERIALS AND METHODS: We included 10,890 participants who underwent a health checkup at Kangbuk Samsung Hospital between January 2006 and December 2006. BRVO was diagnosed from retinal photographs taken for both eyes. Retinal vascular caliber measurements were performed using a computer-assisted program. Risk factors were assessed based on a patient-answered questionnaire and laboratory investigations. Logistic regression analyses were performed to identify potential risk factors for BRVO. RESULTS: The overall prevalence of BRVO was 0.8%. Among all BRVO patients, the mean central retinal artery equivalent (CRAE) was 142.59 µm (±14.63 µm), and the mean central retinal vein equivalent (CRVE) was 203.46 µm (±18.84 µm). The mean CRAE and CRVE of the control eyes were 148.15 µm (± 15.89 µm) and 211.12 µm (±18.54 µm), respectively. There were significant differences in mean CRAE and CRVE between the control group and the BRVO group (P < 0.05). Arterial hypertension was an important risk factor for BRVO (OR: 1.02 (1.01-1.03). CONCLUSIONS: Eyes with BRVO had narrow CRAE and CRVE when compared with age- and gender-matched normal eyes. Generalized attenuation of retinal vessel caliber may be characteristic of eyes with BRVO. Emphasis on blood pressure control is needed for the prevention of BRVO.

Conventional Epi-LASIK and lamellar epithelial debridement in myopic patients with dermatologic keloids.

We report the outcome of conventional epipolis laser in situ keratomileusis (Epi-LASIK, flap-on) and lamellar epithelial debridement (LED; Epi-LASIK, flap-off) in myopic patients with dermatologic keloids. Three patients, who were all noted to be susceptible to keloid scarring, received conventional Epi-LASIK in their right eyes and LED in their left eyes. The patients were followed-up for 6 to 21 months after their surgeries, and the outcomes were then evaluated. In case 1, the preoperative spherical equivalent (SE) was -6.5 diopters (D) in the right eye (OD) and -6.25 D in the left eye (OS). At 21 months postoperatively, the uncorrected visual acuity (UCVA) was 20 / 12.5 in both eyes. In case 2, the preoperative SE was -5.25 (OD) / -6.00 (OS). After six months, the postoperative UCVA was 20 / 12.5 in both eyes. In case 3, the preoperative SE was -4.5 (OD) / -2.0 (OS). The UCVA at the six-month follow-up was 20 / 12.5 in both eyes. No adverse events, including corneal haze, occurred in any of the patients. All three of our patients reported excellent visual outcomes following both conventional Epi-LASIK and LED, despite their histories of keloid formation. The present cases suggest that both Epi-LASIK and LED may be safe and effective techniques for myopic patients with dermatologic keloids.

Simple surgical approach with high-frequency radio-wave electrosurgery for conjunctivochalasis.

OBJECTIVE: To introduce a new simple surgical approach with high-frequency radio-wave electrosurgery to reduce conjunctivochalasis (CCh). DESIGN: Prospective, noncomparative, interventional case series analysis. PARTICIPANTS: Twelve patients (20 eyes) with CCh were recruited from the outpatient service of the Department of Ophthalmology, Kangbuk Samsung Hospital, Seoul, Korea. METHODS: On the inferior bulbar conjunctiva, subconjunctival coagulation was performed with a fine-needle electrode using a high-frequency radio-wave electrosurgical unit (Ellman Surgitron; Ellman International, Inc., Hewlett, NY) in coagulation mode. MAIN OUTCOME MEASURES: Conjunctivochalasis grade; epiphora and dry eye symptoms (the Ocular Surface Disease Index [OSDI]; Allergan Inc., Irvine, CA, holds the copyright); and intraoperative and postoperative complications. RESULTS: Eighteen eyes (90%) recovered a smooth, wet, and noninflamed conjunctival surface within 1 month and remained stable for a follow-up period of 3 months. At 3 months postoperatively, 18 eyes (90%) had grade 0 CCh. There was a statistically significant decrease of the OSDI score at 3 months postoperatively (P < 0.001). CONCLUSIONS: A surgical approach with high-frequency radio-wave electrosurgery produced a significant reduction in CCh and an improvement in symptoms. Radio-wave surgical techniques represent a favorable alternative to surgical treatment of CCh. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Age-related macular degeneration in a screened South Korean population: prevalence, risk factors, and subtypes.

PURPOSE: To identify the prevalence, risk factors, and subtypes of age-related macular degeneration (AMD) in a screened South Korean population. METHODS: A total of 10,890 participants (aged 50-92) who underwent a health check-up at Kangbuk Samsung Hospital from January to December 2006 were included. Fundus photographs and systemic risk factors were assessed. Subtype frequencies of neovascular AMD were recorded according to angiograms. AMD was defined in accord with the international classification and grading system. Logistic regression analyses were performed to identify risk factors for AMD. RESULTS: The mean age of the 10,890 participants was 57.2 +/- 6.3 years (50-92 years), and 56.2% were men. The age-gender-adjusted prevalence of early AMD was 5.07%. Multiple logistic regression analysis showed that age (OR per 10-year increment, 2.22) and high blood pressure (adjusted OR: 1.35) were independent risk factors for early AMD. The age-gender-adjusted prevalence of late AMD was 0.34%. Only age was significantly associated with late AMD. Of 9 exudative AMD patients who received fluorescein angiography or indocyanine green angiography, 6 eyes (66.7%) showed choroidal neovascularization, 2 eyes (22.2%) had polypoidal choroidal vasculopathy (PCV), and 1 eye (11.1%) had retinal angiomatous proliferation. CONCLUSION: In this study, the prevalence of early AMD was similar to other studies though the prevalence of late AMD was low. High blood pressure as well as age was a risk factor of early AMD. South Koreans may have a higher prevalence of PCV than white populations. These findings provide preliminary information for further investigation of AMD in South Koreans.

Changes in central corneal thickness of preserved corneas over time measured using anterior segment optical coherence tomography.

PURPOSE: To measure central corneal thickness (CCT) and investigate serial changes in CCT, using anterior segment optical coherence tomography (AS-OCT) on corneas in storage medium. METHODS: Between July and August 2006, 10 human corneoscleral discs from 5 donors between 19 and 57 years of age were obtained. Corneoscleral rims were excised and were transferred to Optisol-GS (Bausch & Lomb, Irvine, CA). After preservation, AS-OCT (Visante OCT; Carl Zeiss Meditec) was performed on all corneoscleral discs to detect serial changes in CCT. The corneas were measured with AS-OCT at 0.5, 1, 2, 3, 4, 6, and 12 hours and then at 1, 2, 3, and 4 days after preservation. RESULTS: The mean of the baseline CCT measurements obtained with the ultrasound pachymeter was 632.7 microm. The average CCT on AS-OCT decreased to 534 microm in the first day of preservation. As time proceeded, the CCT of each cornea generally decreased. CCT decreased significantly between 30 minutes and 1 hour after preservation (P = 0.004). Also, CCT changes in the interval from preservation to 30 minutes showed a greater decline than during other intervals. Therefore, the most significant change in CCT occurred in the first hour after preservation. CONCLUSION: AS-OCT offers a fast easy method for evaluating human donor corneas for corneal thickness and structural changes without the risk of bacterial contamination or mechanical damage.

Comparison of early postoperative clinical outcomes of photorefractive keratectomy and lamellar epithelial debridement.

PURPOSE: To compare early postoperative clinical outcomes of photorefractive keratectomy (PRK) and lamellar epithelial debridement (LED). SETTING: Department of Ophthalmology, Kangbuk Samsung Hospital, Seoul, Korea. METHODS: This prospective study was of patients randomly assigned to have PRK or LED. In the LED group, an epithelial flap was created using an Amadeus II epikeratome. Postoperative follow-up was at 1, 3, and 7 days and 1, 3, and 6 months. The outcome parameters were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), higher-order aberrations (HOAs), epithelial healing time, and corneal haze. RESULTS: The study comprised 39 patients (76 eyes). The mean preoperative spherical equivalent (SE) was -3.96 diopters (D) +/- 1.24 (SD) in the PRK group and -4.06 +/- 1.39 D in the LED group. Postoperative UCVA was significantly better in the LED group 1 day postoperatively. The UCVA was 20/20 or better in 14.6% in the PRK group and 42.9% in the LED group (P = .006); 20/25 or better in 41.5% and 82.9%, respectively (P = .000); and 20/40 or better in 80.5% and 100%, respectively (P = .006). On subsequent follow-up visits, the UCVA was comparable between groups. No eye lost lines of BCVA at 3 months. There was no difference between groups in postoperative SE refraction, HOAs, or corneal haze. CONCLUSIONS: Lamellar epithelial debridement and PRK had comparable safety and efficacy in the surgical correction of low to moderate myopia. The UCVA was significantly better after LED than after PRK 1 day postoperatively and equivalent thereafter.

The effect of soft contact lenses during the measurement of retinal nerve fiber layer thickness using optical coherence tomography.

PURPOSE: To investigate if the measurement of retinal nerve fiber layer (RNFL) thickness using optical coherence tomography (OCT) is affected by soft contact lens wear. METHODS: This prospective, observational, cross-sectional clinical study looked at 66 eyes in 66 patients who usually wear soft contact lenses everyday and 36 eyes in 36 patients who did not wear contact lenses during the 6 months prior to the study. No patients had pre-existing retinal or optic nerve pathology or other media opacities that might influence the RNFL thickness. All eyes were scanned using the fast RNFL program of the Stratus OCT with and without soft contact lenses on. RESULTS: The mean RNFL thickness in eyes with and without soft contact lenses was 99.4 +/- 9.7 (SD) microm and 100.8 +/- 10.3 micro m, respectively, in contact lens wearers. The mean RNFL thickness in eyes with and without soft contact lenses was 102.8 +/- 10.8 microm and 105.3 +/- 9.9 microm, respectively, in non-contact lens wearers. The mean RNFL thickness in eyes with and without soft contact lenses was significantly different in both groups of patients (p = 0.006, p = 0.001, respectively). The average RNFL thickness without soft contact lenses was statistically significantly increased in non-contact wearers compared with soft contact lens wearers (p = 0.035). CONCLUSIONS: Soft contact lenses may affect the measurement of RNFL thickness using OCT. It is recommended that clinicians be careful in measuring RNFL thickness using OCT with myopic patients using soft contact lenses.