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.

Efficacy of subtenon 20-mg triamcinolone injection versus 0.1% dexamethasone eye drops for controlling inflammation after phacoemulsification: a randomized controlled trial.

A prospective randomized control trial of 140 eyes from 140 patients, who underwent phacoemulsification, was conducted to compare the efficacy of subtenon corticosteroids injection with corticosteroids eye drops for controlling postoperative intraocular inflammation. Seventy patients received subtenon 20-mg triamcinolone injection (TA group), whereas the other 70 patients received 0.1% dexamethasone eye drops (Dexa group) after the uneventful surgeries. We examined and measured anterior chamber inflammation (ACI) score, laser flare-cell metering, conjunctival redness, pain, discomfort, visual acuity, intraocular pressure, and central foveal thickness on 1, 7, 14, 28 and 90 days postoperatively. At one month after the surgery, full recovery (zero ACI score) was found in 43 patients (63.20%) in the Dexa group versus 47 patients (68.10%) in the TA group (p = 0.55). There were no statistically significant differences in aqueous cells (p = 0.37) and flare (p = 0.86) between the two groups at one month. All participants experienced no serious adverse events. In conclusion, we found no statistically significant difference between subtenon 20-mg triamcinolone injection and 0.1% dexamethasone eye drop to control inflammation postoperatively. A single subtenon 20-mg triamcinolone injection could be an alternative anti-inflammatory treatment for an uneventful phacoemulsification.

Characteristics of Corneal Subbasal Nerves in Different Age Groups: An in vivo Confocal Microscopic Analysis.

PURPOSE: To determine the normative characteristics of corneal subbasal nerves in different age groups using laser scanning in vivo confocal microscopy (IVCM). PATIENTS AND METHODS: This descriptive observational study recruited healthy subjects (aged 20-60 years) from Siriraj Health-Screening Center. Excluded were individuals who had abnormal ocular symptoms, previous ocular surgery, a history of any diseases related to systemic and/or corneal neuropathy, or abnormal corneal sensitivity. Corneal IVCM (HRT3/Rostock Corneal Module) was performed at the central cornea to analyze the subbasal nerve plexus. The corneal nerve characteristics, comprising the number and density of nerves (main nerve trunks, branches, and total nerves) were analyzed using the NeuronJ program, and the corneal nerve tortuosity was graded. The correlations between the subbasal nerve density, tortuosity and age were then analyzed. RESULTS: Eighty subjects were enrolled, with twenty in each of four age groups (20-30, >30-40, >40-50, and >50-60 years). Overall, the mean number and density of main nerve trunks were 27.93±0.81/mm2 and 11.22±0.30 mm/mm2, respectively. As of the nerve branches, the average number and density were 103.56±2.37/mm2 and 9.15±0.30 mm/mm2, respectively. The total nerve density was 20.37±0.39 mm/mm2. There were no significant differences between subbasal nerve parameters of the four age groups. It is noteworthy that 65% of the subjects aged over 40 years revealed high-grade nerve tortuosity. CONCLUSION: The corneal subbasal nerve numbers and densities were not significantly different among a healthy population aged 20-60 years. However, there was a trend towards high tortuosity of the corneal nerve in people aged over 40 years.

Efficacy of Swept-source Optical Coherence Tomography in Axial Length Measurement for Advanced Cataract Patients.

SIGNIFICANCE: A major limitation of standard time-domain optical coherence tomography-based biometers (TD-OCT) is an inability to measure the axial length (AL) in advanced cataract. A new device that uses swept-source optical coherence tomography (SS-OCT) allows better light penetration. Hence, a considerable number of cataract patients who failed AL measurement by TD-OCT can be recovered by SS-OCT. PURPOSE: The purposes of this study were to evaluate the efficacy of an SS-OCT for AL measurement in advanced cataract patients and to identify characteristics of lens opacity that impede the AL measurement. METHODS: Advanced cataract patients who were unable to obtain AL measurement using a standard TD-OCT-based optical biometer (IOLMaster500; Carl Zeiss Meditec, Jena, Germany) were recruited in this study. The AL was remeasured using SS-OCT (IOLMaster700), followed by measurement with immersion ultrasonography (IU). The percentage of patients who achieved AL measurement by SS-OCT was recorded. The AL obtained from SS-OCT was then verified by comparing with the AL derived from IU. The cataract type of each patient was classified according to standard Lens Opacity Classification III score. The association between characteristics of cataract and successful AL measurement by SS-OCT was analyzed. RESULTS: Sixty-four eyes that failed AL measurement from TD-OCT were included. Fifty-six eyes (87.5%) were able to be measured by SS-OCT (95% confidence interval, 77.23 to 93.53%). The AL obtained by SS-OCT showed very high agreement with those derived from IU (intraclass correlation coefficient, 0.99). There was no statistically significant correlation between characteristics of lens opacity and the capability of SS-OCT for AL measurement (P > .05). However, there was a trend toward an inability to measure the AL in cataracts with a high grade of lens opacity. CONCLUSIONS: The efficacy of SS-OCT-based optical biometer was excellent. Of the patients with advanced cataract who failed the AL measurement by TD-OCT, 87.5% could be recovered by SS-OCT. However, there was no specific type of lens opacity associated with a failure of AL measurement using SS-OCT.

Tear film change and ocular symptoms after reading printed book and electronic book: a crossover study.

PURPOSE: To evaluate and compare tear film changes and ocular symptoms after reading an electronic book (e-book) and a printed book. STUDY DESIGN: Clinical and experimental. METHODS: Crossover study was conducted in 30 healthy volunteers, some of whom read an e-book and others a printed book for 20 minutes and then switched the following week. Tear meniscus height (TMH), non-invasive break-up time (NIBUT), fluorescein break up time (FBUT), corneal and conjunctival staining score, and questionnaires about seven ocular symptoms were evaluated before and after reading by both reading methods. RESULTS: After reading an e-book, FBUT and NIBUT were significantly decreased (p<0.001for both). Similar to printed book readers (p=0.006, p=0.04, respectively). TMH and corneal and conjunctival staining score showed no significant differences in either group. Comparing the two groups, the e-book group showed more decrease in TMH, FBUT, and NIBUT (p>0.05). Ocular symptoms were significantly increased in both groups. The e-book group showed more increase in all symptoms, but only tearing (p=0.03) and burning sensation (p=0.02) were significantly different. CONCLUSIONS: Reading an e-book affected tear film instability and significantly increased burning sensation and tearing to a larger extend than reading a printed book.

Comparison of central corneal thickness measurements in corneal edema using ultrasound pachymetry, Visante anterior-segment optical coherence tomography, Cirrus optical coherence tomography, and Pentacam Scheimpflug camera tomography.

PURPOSE: To compare the central corneal thickness (CCT) measurements in subjects with corneal edema using ultrasound pachymetry, Visante anterior-segment optical coherence tomography (OCT), Cirrus OCT, and Pentacam Scheimpflug camera tomography. METHODS: This prospective cross-sectional study included 46 eyes of 33 patients with corneal edema and a CCT exceeding 550 µm evaluated by ultrasound pachymetry, Visante OCT, Cirrus OCT, and Pentacam. Two observers measured each eye twice. Intraobserver and interobserver reproducibility were determined and agreement among the devices calculated. RESULTS: CCT was measured in 40 eyes of 29 patients. Regardless of the CCT, the measurements obtained using Visante OCT, Cirrus CCT, and ultrasound pachymetry were well correlated. Interobserver and intraobserver reproducibility were high among the three devices. Pentacam overestimated the results compared with the other devices, and ultrasound pachymetry was unmeasurable in six (13%) eyes with very thick and opaque corneas. In eyes with mild corneal edema (CCT 551-650 µm), measurements from the four devices were comparable. CONCLUSION: All devices reliably measured the CCT <650 µm. In eyes with edema exceeding 650 µm, CCT measurements from the Visante OCT, Cirrus OCT, and ultrasound pachymetry devices showed good reproducibility and were well correlated, while the Pentacam overestimated the values compared to the other devices. Pentacam and ultrasound pachymetry should not be used in eyes with extreme corneal edema and opacity.

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.

Comparison of corneal astigmatism measurements of 2 optical biometer models for toric intraocular lens selection.

PURPOSE: To compare corneal astigmatism measurements obtained using a new optical biometer (AL-Scan) and a standard biometer based on partial coherence interferometry (IOLMaster 500) for toric intraocular lens (IOL) selection. SETTING: Siriraj Hospital, Mahidol University, Bangkok, Thailand. DESIGN: Prospective comparative study. METHODS: Keratometry (K) readings were taken with the 2 biometers in eyes of cataract patients. The corneal astigmatism readings from the 2 devices were compared. The cylinder measurements were transformed into J0 and J45 vector components for analysis, and the devices' values were compared using the paired t test. Correlation coefficients were calculated. The Bland-Altman method was used to evaluate the agreement between the sets of measurements. RESULTS: One hundred thirty-seven eyes (81 patients) were enrolled. The magnitude of astigmatism between the new biometer 2.4 mm zone and the standard biometer was similar (P = .19). There was a statistically significant difference between values from the new biometer 3.3 mm zone and the standard biometer (P < .05). There was good correlation in the overall magnitude of astigmatism between devices. There was a trend of low correlation toward the flat cornea (K <43.0 diopters [D]), low corneal cylinder (<1.0 D), and with-the-rule astigmatism. The IOL toricity calculated from both devices was similar. CONCLUSIONS: Corneal astigmatism measurements with the 2 biometers were similar in magnitude, especially in 2.4 mm zone of the new biometer. There was no difference in the toric IOL selections between the devices. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Comparison of ocular biometry and intraocular lens power using a new biometer and a standard biometer.

PURPOSE: To compare the repeatability and reproducibility of ocular biometry and intraocular lens (IOL) power obtained with a new optical biometer (AL-Scan) and a standard optical biometer (IOLMaster 500). SETTING: Siriraj Hospital, Mahidol University, Bangkok, Thailand. DESIGN: Prospective comparative study. METHODS: Two independent operators measured eyes with cataract using both biometers. The keratometry values, axial length, anterior chamber depth, white-to-white (WTW) corneal diameter, and IOL power calculated using the Holladay 1 formula obtained with each device were recorded. Intraoperator repeatability and interoperator reproducibility of both devices were analyzed using the intraclass correlation coefficient (ICC). The agreement in ocular biometry and IOL power between the 2 devices was evaluated by the Bland-Altman method. RESULTS: The study recruited 137 eyes of 81 patients. The repeatability and reproducibility of both devices were high for all ocular biometry measurements (ICC, 0.87-1.00). Except for the WTW corneal diameter (ICC, 0.44), the agreement between the biometers was also high (ICC, 0.98-0.99). The IOL powers calculated by the Holladay 1 formula were similar between the 2 biometers. CONCLUSION: The new optical biometer provided excellent repeatability and reproducibility for all ocular biometry. Agreement with the standard optical biometer was good except for the WTW corneal diameter.

Agreement of IOL power and axial length obtained by IOLMaster 500 vs IOLMaster 500 with Sonolink connection.

BACKGROUND: The accurrate and expedient ocular biometry is essential for modern cataract surgery. IOLMaster 500, one of the most popular partial coherence interferometry (PCI) device, has been widely used. However, with the PCI device, it is difficult to obtain the axial length through densely opaque media. With the current version of IOLMaster 500, a unique feature is added to link with the Synergy immersion A-scan ultrasound (sonolink connection). In case of failure to measure axial length by IOLMaster 500, the axial length can be obtained by ultrasound, and then transferred to IOLMaster 500 for the IOL power calculation. This study aims to compare the results and evaluate the agreement between IOL power and axial length obtained by IOLMaster 500 and IOLMaster 500 with sonolink connection. METHODS: A prospective study of 60 eyes in 60 mild-to-moderate cataract patients was conducted under Institutional Ethics Committee approval. Keratometry (K) and axial length (AL) of all eyes were measured using IOLMaster 500 (Carl Zeiss, Germany), then IOL power was generated using Holladay 1 formula (group 1). After 5 min, the K measurements were repeated with IOLMaster 500 and the AL were measured again using the Synergy A-scan ultrasound (Accutome, USA). Then, the AL data were transferred to IOLMaster 500 via the sonolink connection to generate the IOL power using the same setting (group 2). The IOL power and AL were compared between the two groups, and the agreement was evaluated using intraclass correlation coefficient (ICC) and the Bland-Altman method. RESULTS: The mean IOL power in group 1 was 21.04 + 2.36 D and group 2 was 21.03 + 2.36 D. The mean AL in group 1 was 23.35 + 0.86 mm and in group 2 was 23.36 + 0.86 mm. There was no statistically significant difference in IOL power and AL between the two groups. The agreements in IOL power and AL between both groups were high (ICCs = 0.997 for IOL power and 0.993 for AL) CONCLUSIONS: The IOL power and AL derived from both groups were similar. The agreements between them were high.

Comparison of corneal astigmatism and axis location in cataract patients measured by total corneal power, automated keratometry, and simulated keratometry.

PURPOSE: To compare the corneal astigmatism (magnitude and axis location) derived by total corneal power (TCP), automated keratometry, and simulated keratometry. SETTING: Siriraj Hospital, Mahidol University, Bangkok, Thailand. DESIGN: Prospective comparative study. METHODS: Eyes with previous ocular surgery or abnormalities were excluded. All patients were examined with the ARK 730A autokeratometer and the Galilei analyzer. The steepest and flattest corneal power along with the steepest axis of the TCP, automated keratometry, and simulated keratometry were recorded. Vector analysis (J0 and J45) was calculated. Analysis of variance with Bonferroni correction was performed for multiple comparisons. Outcome measures were the magnitude and axis location of astigmatism. RESULTS: One hundred eyes of 100 cataract patients were randomly selected. There was no statistically significant difference in the mean steepest axis between TCP (93.31 ± 68.75 [SD]), automated keratometry (94.24 ± 64.78), and simulated keratometry (92.42 ± 64.30). However, the mean magnitude of astigmatism measured by TCP (1.23 ± 0.75) was significantly higher than that measured by automated keratometry (0.93 ± 0.68) (P=.01) but not than that measured by simulated keratometry (1.08 ± 0.68) (P=.43); there was no statistically significant difference in J0 or J45. Twenty two (40%) of 54 eyes with more than 1.00 diopter of TCP astigmatism had more than 10 degrees of axis difference from automated keratometry. CONCLUSIONS: The magnitude of TCP astigmatism was higher than that of automated keratometry. The axis location was similar. However, there was more than 10 degrees of axis difference between automated keratometry and TCP in patients with high astigmatism. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.