Double peak axial length measurement signal in cataract patients with epiretinal membrane.

PURPOSE: To evaluate the accuracy of axial length (AL) measurement for intraocular lens (IOL) calculation in patients with cataract and epiretinal membrane (ERM). METHODS: This prospective, cross-sectional study was performed in cataract patients with ERM. All subjects were sent for standard optical biometry, prepared for cataract surgery. Signals of AL measurement were detected as double peaks and recorded as AL1 (first peak), and AL2 (second peak). The IOL power was calculated from AL1 and AL2, and reported as IOL1 and IOL2. The IOL2 was chosen for cataract surgery in all cases. Postoperative predictive errors were compared between IOL1 and IOL2. RESULTS: Thirty-seven eyes from 37 patients were included. Mean AL1 was significantly shorter than AL2 (23.13 ± 1.28 vs. 23.60 ± 1.34 mm, p < 0.001), resulting in higher power of IOL1 than IOL2 (mean difference was 1.53 ± 0.96 diopters, p < 0.001). At 3-months post-operation, twenty-nine eyes (78.4%) (95% CI 62.8%-88.6%) showed refractive error within ± 0.5 diopter and all eyes were within ± 1.0 diopter. Postoperative predictive errors including mean arithmetic error (ME) and mean absolute error (MAE) of IOL2 were significantly lower than those of IOL1 (ME: IOL1 vs. IOL2, -0.94 ± 0.91 vs. 0.08 ± 0.51; MAE: 0.97 ± 0.88 vs. 0.39 ± 0.33 diopter, all p < 0.001). CONCLUSIONS: AL measurement in ERM can be detected as a double peak signal during biometric measurement. The IOL power calculated from the first and second peak signals is significantly different. However, the IOL power derived from the second peak signal provides better refractive outcomes. The results suggest that the second peak signal represents an accurate AL measurement.

A 5-year retrospective record review of hospital-based low-vision rehabilitation in Thailand.

PURPOSE: To investigate the quality-of-life-related goals of low-vision patients, the causes of visual impairment, and the low-vision rehabilitation services at a Thai national tertiary referral center. SUBJECTS AND METHODS: A review was conducted on the medical records of patients attending the Low Vision Rehabilitation Clinic, Siriraj Hospital, Bangkok, Thailand, between 2012 and 2016. RESULTS: A total of 992 patient records were included, comprising of 760 adults (aged over 15 years) and 232 children (aged ≤15), with a mean age of 52.2 and 5.4 years, respectively. The retina was the most common anatomic site of visual impairment. Among the adults, the most common ocular condition was retinitis pigmentosa (28.3%), followed by age-related macular degeneration (10.3%), glaucoma (10.0%), and diabetic retinopathy (9.6%). As for the children, the most common ocular conditions were cortical visual impairment (17.7%), optic nerve hypoplasia (13.4%), and retinopathy of prematurity (9.5%). More patients had low vision (a visual acuity of <6/18-3/60) than blindness (a visual acuity below 3/60). The most commonly stated goals among the adults were reading, writing, and performing near tasks (34.7%), and independent mobility (21.3%), whereas for children, the most frequently indicated goal was visual and developmental stimulation (38.4%). The services most often provided for the adults were the prescribing of visual aid devices (51.8%) and orientation and mobility training (40.7%), while the children most often received visual and developmental stimulation provided by a multidisciplinary team (33.8%). The Thai Government's Universal Health Care Coverage scheme was the most commonly used medical insurance. CONCLUSION: Data from this study can be used to improve low-vision patient care and rehabilitation services, and as input to the further development of national health care policies for low-vision patients.

Clinical comparison of a new swept-source optical coherence tomography-based optical biometer and a time-domain optical coherence tomography-based optical biometer.

PURPOSE: To evaluate the repeatability and reproducibility of a newer swept-source optical biometer and to compare it with a standard partial coherence interferometry (PCI) biometer. SETTING: Siriraj Hospital, Mahidol University, Bangkok, Thailand. DESIGN: Prospective comparative study. METHODS: One hundred eyes from 100 cataract patients were enrolled in this study. Each patient was measured with 2 optical biometers, a newer swept-source optical biometer (IOLMaster 700) and a standard partial coherence interferometry biometer (IOLMaster 500) by 2 independent operators. The keratometry, axial length (AL), anterior chamber depth, white-to-white corneal diameter, and intraocular lens (IOL) power, calculated by the SRK/T and the Haigis formulas for each device, were recorded. Intraoperator repeatability and interoperator reproducibility of both devices were analyzed using intraclass correlation coefficients (ICCs). Agreement of ocular biometry and IOL power between the 2 devices was evaluated using the Bland-Altman method. RESULTS: The repeatability and reproducibility of the swept-source and standard biometers were high for all ocular biometry parameters (ICC, 0.93-1.00). The agreement between the 2 biometers was also high (ICC, 0.92-1.00). The IOL powers obtained from both devices were not distinct. Because of the density of the cataracts, the AL in 5 eyes could be measured only by the swept-source biometer. CONCLUSIONS: Repeatability and reproducibility of a swept-source optical biometer was excellent and agreement with a standard biometer was very high. Better lens penetration ability and AL measurements were obtained with the swept-source biometer than with the standard biometer. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

A comparative study of visual evoked potentials in optic neuritis and optic neuritis with multiple sclerosis.

OBJECTIVE: To compare the visual evoked potentials (VEP) in patients with acute optic neuritis, recurrent optic neuritis, and optic neuritis with multiple sclerosis. MATERIAL AND METHOD: The authors retrospectively reviewed VEP latency records of the patients with optic neuritis in Siriraj Hospital from 1995 to 2005 and divided them into three groups, acute optic neuritis, recurrent optic neuritis, and optic neuritis with multiple sclerosis (ON/MS). The patients with non-recordable VEP in the analysis were excluded. Comparison of the mean latency of the VEP in affected eyes among the three groups was statistically analyzed by a nonparametric independent sample test. RESULTS: Twenty-two patients with acute optic neuritis, 8 patients with recurrent optic neuritis, and 22 patients with ON/MS participated in this study. The mean age among the three groups was not statistically significant. The median value of the latency of flash VEP (fVEP) and pattern reversal VEP (PRVEP) in the acute optic neuritis group was shorter than that of the recurrent optic neuritis group, and statistically significant (fVEP p = 0.012; PRVEP, p = 0.004). The median value of the latency of PRVEP in the acute optic neuritis group was shorter than that of the ON/MS group, and statistically significant (PRVEP p = 0.002). The median value of the latency of both fVEP and PRVEP in the recurrent optic neuritis group and ON/MS group were delayed with no statistical significance (fVEP p = 0.458; PRVEP, p = 0.403). CONCLUSION: The VEP can be used to demonstrate the demyelinating mechanism of optic neuritis and optic neuritis with multiple sclerosis, but cannot determine the susceptibility of the patients with acute ON to become MS. The significantly delayed latency of VEP in recurrent optic neuritis is possibly caused by severe damage of the optic nerve conduction from recurrent attacks.