Measurement of Precorneal Tear Film Using Scheimpflug Camera and Relationship with Parameters for Dry Eye

PURPOSE: To compare the anterior segment parameters including precorneal tear film thickness (PTFT) using Pentacam(R) (Oculus, Wetzlar, Germany) between normal control and dry eye groups and to examine the relationships between the PTFT and other parameters for dry eye. METHODS: The present study included 23 normal controls (31 eyes) and 25 patients with dry eyes (31 eyes). We compared measurements including PTFT, corneal thickness and astigmatism using Pentacam(R) and analyzed the correlations among the PTFT and fluorescein tear break-up time (FBUT), Schirmer I test (without anesthesia), and ocular surface disease index (OSDI). RESULTS: The mean PTFT in dry eyes (21.1 +/- 2.0 microm) was significantly thinner than in normal eyes (37.6 +/- 2.0 microm; p < 0.01). In the dry eye group, the corneal thickness was thicker than in the normal eye group but there were no clinically significant differences. The dry eye group experienced more frequent and severe corneal astigmatism compared with the normal group. OSDI scores showed a weak negative correlation with objective clinical measures of dry eye (FBUT, Schirmer I test) but was not statistically significant. However, OSDI was statistically significantly negatively correlated with PTFT (r = -0.46, p < 0.01). The PTFT showed a weak positive correlation with FBUT and Schirmer I test without statistical significance. CONCLUSIONS: The mean PTFT using Pentacam(R) in the dry eye group was thinner than in the normal group. Additionally, the PTFT was correlated with subjective symptoms. Therefore, the PTFT measurement using Pentacam(R) could be considered a useful method for diagnosis and treatment of dry eye.

Relationship between Dry Eye Parameters and Anterior Corneal Higher-Order Aberrations Measured by Two Different Instruments

PURPOSE: To compare the corneal first surface higher-order aberrations (HOAs) of normal subjects and patients with dry eye using KR-1W(R) (Topcon Corp., Tokyo, Japan) and Pentacam(R) HR (Oculus Inc., Dutenhofen, Germany). We analyzed the relationship between the aberrations and the diagnostic parameters of dry eye. METHODS: We evaluated anterior corneal HOAs in 71 normal eyes and 71 dry eyes using KR-1W(R) and Pentacam(R). Dry eye patients were examined for fluorescein staining, tear break-up time (TBUT), and Schirmer I test. Ocular Surface Disease Index (OSDI) was used for assessment of subjective symptoms in dry eye patients. RESULTS: HOAs measured by both instruments were greater in the dry eye group than in the control group, although HOAs using KR-1W(R) only achieved statistical significance. The anterior corneal HOAs measured by the 2 instruments were significantly correlated with superficial punctate keratitis. Moreover, TBUT and the Shirmer I test negatively correlated, and OSDI positively correlated, with anterior corneal HOAs. CONCLUSIONS: The HOAs in patients with dry eye were significantly different from controls and tended to increase with disease severity. KR-1W(R) might be more useful than Pentacam(R) to detect tear film instabilities.

Comparison of Central Corneal Thickness and Anterior Chamber Depth Measured Using Three Different Devices

PURPOSE: To compare measurements of central corneal thickness (CCT) and anterior chamber depth (ACD) obtained using Galilei(TM), Pentacam(R) (Oculus, Wetzlar, Germany) and Lenstar(R) (Haag-Streit, Koeniz, Switzerland) and analyze the measurement agreements. METHODS: CCT and ACD were measured using Galilei(TM), Pentacam(R) and Lenstar(R) in 47 eyes of 25 healthy subjects. The measurements were compared among the 3 devices. RESULTS: The average CCT measurements using Galilei(TM), Pentacam(R) and Lenstar(R) were 552.6 +/- 29.41 microm, 543.9 +/- 30.50 microm and 537.5 +/- 30.26 microm, respectively. The measurements significantly correlated with each other (r > 0.9, p 0.9, p < 0.001), but were statistically significantly different (p = 0.034). The CCT 95% limits of agreement (LoA) between Galilei(TM) and Pentacam(R), Pentacam(R) and Lenstar(R) and Lenstar(R) and Galilei(TM) were 31.95 microm, 44.76 microm and 46.57 microm, respectively and 95% ACD LoA were 0.46 mm, 0.32 mm and 0.28 mm, respectively. CONCLUSIONS: CCT and ACD measured using the 3 devices were highly correlated with each other but the measurements were statistically different. Therefore, the measurements were not interchangeable and these differences should be considered in clinical use.

Comparison of Corneal Higher-Order Aberrations Measured with Two Instruments Using Scheimpflug Camera System

PURPOSE: To compare the corneal higher-order aberrations (HOAs) of normal young subjects using Galilei(TM) G4 (Zeimer, Port, Switzerland) and Pentacam(R) (Oculus Inc., Wetzlar, Germany). METHODS: Corneal HOAs were measured using Galilei(TM) G4 and Pentacam(R) in 41 healthy individuals (41 eyes). Intraclass correlation coefficients (ICCs) were obtained to evaluate the repeatability of the 2 devices. Differences in HOAs between the 2 instruments were analyzed with a paired t-test and correlations evaluated. RESULTS: All ICCs measured using Galilei(TM) G4 and Pentacam(R) showed more than moderate repeatability (>0.81) except trefoil, tetrafoil, 4th and 5th HOAs. When comparing the measurements obtained with Galilei(TM) G4 and Pentacam(R), total HOAs, spherical aberration (SA), secondary astigmatism and 5th total HOAs were statistically significantly different between the 2 device (all p < or = 0.001). In addition, Galilei(TM) G4 and Pentacam(R) showed discrepancy among all corneal HOAs items. Although the total corneal HOAs and the SA were significantly correlated, other HOA measurements generally exhibited a low correlation. CONCLUSIONS: Corneal HOAs obtained by the 2 instruments cannot be used interchangeably due to their differences and discrepancy although corneal HOAs measured using Galilei(TM) G4 and Pentacam(R) showed relatively high repeatability.

The Relationship between the Nuclear Density Using Scheimpflug Imaging with Phacoemulsification Parameters

PURPOSE: To evaluate the correlation between nuclear density measured using the Pentacam(R) (Oculus Optikgerate GmbH, Wetzlar, Germany) Scheimpflug imaging system and phacoemulsification parameters. METHODS: The nuclear density was measured using maximal nuclear density with ImageJ, Pentacam(R) nucleus staging (PNS), average value and maximal value in lens densitometry. Intraoperatively, effective phaco time (EPT) and balanced salt solution (BSS) used were noted and compared with the nuclear density calculation methods. As an index of corneal endothelial cells, the changes in cell density (CD) were compared with the nuclear density. RESULTS: Regarding EPT, maximal nuclear density with ImageJ (r = 0.379, p < 0.01) and PNS (r = 0.367, p < 0.01) were correlated positively, but the other methods were not correlated. Concerning BSS used, maximal nuclear density with ImageJ (r = 0.279, p = 0.03) and PNS (r = 0.286, p = 0.04) were positively correlated, but the other methods were not correlated. The specular microscopy showed that as the nuclear density increased, the postoperative CD tended to decrease, but without statistical significance. CONCLUSIONS: Preoperative nuclear density measurements using maximal nuclear density with ImageJ or PNS were correlated with phacoemulsification parameters.

Effects of Topical Tranilast on Corneal Haze with the Pentacam(R) after Photorefractive Keratectomy

PURPOSE: To evaluate the inhibitory effect of tranilast on formation of corneal haze using the Pentacam(R) after photorefractive keratectomy (PRK). METHODS: A prospective, randomized, paired eye study was performed. A total of 60 eyes from 30 patients were enrolled in the present study. Eyes were categorized as myopic eyes or =-5 D. Patients undergoing PRK were randomized to receive tranilast in one eye and no medication in the contralateral eye. Three months postoperatively, corneal haze was measured with the Pentacam(R) and compared between the 2 groups. RESULTS: Statistical differences were not found in preoperative data in the tranilast or control groups (all P > 0.05). There was a strong decreasing density trend from the apex to the 3 mm radius in both groups (P 0.05). CONCLUSIONS: The use of tranilast after PRK did not inhibit corneal opacity. Additionally, Pentacam(R) can provide a useful objective measure of corneal haze.

Measurement Comparison of Anterior Segment Parameters between AL-Scan(R) and Pentacam(R)

PURPOSE: To investigate the clinical availability of AL-Scan(R) (Nidek, GAMAGORI, Japan) by comparing anterior segment parameters measured with AL-Scan(R) and Pentacam(R) (Oculus, Wetzlar, Germany). METHODS: Seventy-three patients (117 eyes) who received refractive surgery at our hospital were tested with AL-Scan(R) and Pentacam(R). We compared measurements including anterior chamber depth, central corneal thickness, white-to-white, and corneal curvature. RESULTS: When comparing measurements obtained with AL-Scan(R) and Pentacam(R), the anterior chamber depth (p < 0.001), central corneal thickness (p < 0.001) and 2.4 mm zone K value (p = 0.038) showed significant differences; the white-to-white (p = 0.348) and 3.3 mm zone K value (p = 0.429) showed no significant differences. All AL-Scan(R) and Pentacam(R) parameters had a strong positive linear correlation (p < 0.001). The Bland-Altman plots showed a high degree of agreement between AL-Scan(R) and Pentacam(R) in all parameters except for anterior chamber depth. CONCLUSIONS: AL-Scan(R) is convenient to use clinically because simultaneous measurements of ocular biometry including axial length, intraocular lens power, and topography are possible. However, because differences in some anterior segment parameters exist when compared with Pentacam(R), measurements with AL-Scan(R) may require comparisons with other instruments.

Comparative Analysis of Corneal Refractive Power Measured with AL-Scan(R), Autokeratometer, and Pentacam(R)

PURPOSE: To investigate clinical availability of AL-Scan(TM) (Nidek, Gamagori, Japan) by comparing corneal refractive power with AL-Scan(TM), Autokeratometer(TM) (Topcon KR-1, Tokyo, Japan) and Pentacam(TM) (Oculus, Wetzlar, Germany) devices. METHODS: Seventy-one patients (142 eyes) who visited our hospital for refractive surgery were tested using AL-Scan(R), Autokeratometer and Pentacam(R) and corneal refractive power was compared among devices. RESULTS: When comparing measurements with AL-Scan(R), Autokeratometer and Pentacam(R), the mean corneal refractive power was 43.37 +/- 1.32 D (2.4 mm zone), 43.35 +/- 1.32 D (3.3 mm zone), 43.36 +/- 1.35 D, and 43.35 +/- 1.36 D respectively and showed no significant differences. Corneal refractive power had strongly positive linear correlation (p < 0.001) and Bland-Altman plots showed high degree of agreement among AL-Scan(R), Autokeratometer and Pentacam(R) devices. CONCLUSIONS: Because measuring ocular biometry with AL-Scan(R) including axial length, intraocular lens power calculation and topography simultaneously is possible, clinical use is convenient. Corneal refractive power was not different when compared with autokeratometer and Pentacam(R) devices, thus, AL-Scan(R) can be used in the clinical environment.

Comparison of Anterior Chamber Depth Obtained from Applanation and Optical Principle Devices

PURPOSE: To assess the reproducibility and reliability of applanation A-scan ultrasonography (Pacscan 300A, Sonomed Inc., Chicago, IL, USA) and optical measurements with IOL Master(R) (Carl Zeiss Meditec, Germany), Pentacam(R) (Oculus, Wetzlar, Germany), and Orbscan II(R) (Orbtek Inc., Laredo, TX, USA) when measuring anterior chamber depth (ACD). METHODS: In this study of 188 eyes of 94 patients, ACD estimation prior to cataract surgery was preformed by the applanation A-scan method and IOL Master(R), Pentacam(R), and Orbscan II(R) optical methods. Repeatability from each device was evaluated by coefficient of variation, standard deviation, and intraclass correlation coefficient. RM-ANOVA on Ranks was used to compare the differences in ACD among the devices. The Bland-Altman plot was performed to assess agreement in measurements between the devices. RESULTS: The mean ACD according to the applanation A-scan method and IOL Master(R), Pentacam(R), and Orbscan II(R) optical methods were 2.89 +/- 0.49 mm, 3.25 +/- 0.45 mm, 3.21 +/- 0.46 mm, and 3.19 +/- 0.47 mm, respectively, and the differences were statistically significant (p < 0.01). The coefficient of variation for the 4 methods was 2.50% in the A-scan, 0.87% in the IOL Master(R), 1.25% in the Pentacam(R), and 1.04% with Orbscan II(R), and reproducibility was higher with the optical principle devices. The correlation coefficient between A-scan and IOL Master(R) was 0.65, between IOL Master(R) and Pentacam(R) 0.91, between IOL Master(R) and Orbscan II(R) 0.90, between A-scan and Pentacam(R) 0.69, between A-scan and Orbscan II(R) 0.71, and between Pentacam(R) and Orbscan II(R) 0.93. CONCLUSIONS: Applanation A-scan provided lower measurements for ACD compared with IOL Master(R), Pentacam(R) and Orbscan II(R). There was good agreement between results obtained with the latter 3 methods, and reproducibility was high with optical measurements. The coefficient of variation was low for IOL Master(R).

Comparison of Intraocular Pressure Correction Programs in Pentacam after Corneal Refractive Surgery

PURPOSE: To evaluate the accuracy of Pentacam(R) built-in 5 intraocular pressure (IOP) correction programs used to measure the IOP of patients who received corneal refractive surgery. METHODS: IOP of 124 eyes from 62 patients who underwent epipolis laser in situ keratomileusis was measured with Goldmann applanation tonometry (GAT) at 6 months pre- and post-operatively. The collected data was input into Pentacam(R), calculated by 5 correction programs, Ehlers, Shah, Dresden, Orssengo / Pye, Kohlhaas, and compared. RESULTS: The GAT-based pre- and post-operative IOP was 15.75 +/- 2.24 mm Hg, and 10.72 +/- 2.31 mm Hg, respectively, revealing the post-operative IOP to be significantly lower than the pre-operative IOP (p < 0.001). Among the 5 correction programs within Pentacam(R), Ehlers program showed little difference between pre- and post-operative IOP values (p = 0.228) and the post-operative correction value showed no significant difference with the pre-operative GAT value (p = 0.413). CONCLUSIONS: The Ehlers program is the most accurate among the 5 Pentacam(R) correction programs evaluated in the present study, and can be a useful tool for correcting the true IOP of patients which tends to be higher after corneal refractive surgery.

The Change of Anterior Chamber Parameters with Pentacam(R) after Intravitreal Injection

PURPOSE: To evaluate the changes of anterior chamber parameters and intraocular pressure (IOP) with Pentacam(R) after intravitreal injection. METHODS: A total of 76 eyes of 76 patients received an intravitreal injection of either triamcinolone acetonide (TA) or bevacizumab. Twelve patients were treated with an intravitreal injection of TA 0.1 ml, 16 patients were treated with an intravitreal injection of TA 0.05 ml, while the remaining 48 patients received a bevacizumab 0.05 ml injection. All patients underwent anterior chamber depth, anterior chamber angle, and anterior chamber volume evaluation with Pentacam(R) before and 5 minutes after injection. Additionally, IOP measurements were taken 5 minutes before and 5 minutes, 30 minutes, 1 hour and 1 day after injection. RESULTS: Anterior chamber depth, anterior chamber angle, anterior chamber volume, and IOP changes in patients receiving TA 0.1 ml were 0.4 +/- 0.11 mm, 10.2 +/- 4.1degrees, 33.7 +/- 5.9 mm3 and 18.8 +/- 12.1 mm Hg, respectively. Anterior chamber depth, anterior chamber angle, anterior chamber volume, and IOP changes in patients receiving TA 0.05 ml were -0.01 +/- 0.05 mm, 2.4 +/- 3.2degrees, 5.8 +/- 9.5 mm3 and 4.8 +/- 7.4 mm Hg, respectively. Anterior chamber depth, anterior chamber angle, anterior chamber volume, and IOP changes in patients receiving bevacizumab were 0.28 +/- 0.99 mm, 0.8 +/- 4.0degrees, 7.1 +/- 9.6 mm3 and 5.4 +/- 6.3 mm Hg, respectively. There was a significant difference between TA 0.1 ml and 0.05 ml. However, there was no significant difference between TA 0.05 ml and bevacizumab 0.05 ml. CONCLUSIONS: Because of similar anterior chamber parameters changes after 0.05 ml intravitreal injection with TA or bevacizumab, early period IOP increases due to intravitreal volume expansion. Intravitreal 0.05 ml injections do not require any other procedures for controlling IOP 30 minutes after injection.