Agreement in central corneal thickness measurement between Corvis ST and ocular response analyzer.

PURPOSE: To evaluate the agreement and interchangeability of noncontact devices of ocular response analyzer (ORA) and the Corvis ST in central corneal thickness measurement. METHODS: In this prospective comparative study, central corneal thickness (CCT) readings of 284 healthy, nonglaucoma subjects, without previous ocular surgery, were measured with ORA and Corvis ST. Only data from right eyes were analyzed. The mean values of CCT measurements by the ORA versus Corvis ST were compared with the paired sample t test. Bland-Altman plots and 95% limits of agreement (95% LOA) were used to assess the agreement between the measurements of the two devices. RESULTS: The mean (± standard deviation) age of the participants was 28.0 ± 4.9 years, and 36.6% were male. The mean CCT measurements were 555 ± 32 µm by the ORA and 536 ± 32 µm with the Corvis ST (P < 0.001). The Pearson correlation coefficient was 0.964 (P < 0.001). The 95% LOA between the ORA and the Corvis ST was 2.2 to 35.9 µm. CONCLUSIONS: The ORA measured the CCT up to 35.9 µm greater than Corvis ST. Therefore, the two devices may not be used interchangeably for measuring CCT.

Intraocular Pressure Before and After Corneal Refractive Surgery: A Prospective Comparison of Corvis ST and Ocular Response Analyzer.

PRECIS: The study showed that Corvis ST's bIOP and ORA's IOPcc do not agree well, before or after PRK, and may not be used interchangeably. bIOP remained unchanged after PRK. PURPOSE: To evaluate the agreement between the biomechanically-corrected intraocular pressure (bIOP) measured by the Corvis-ST and the cornea-compensated IOP (IOPcc) measured by the Ocular Response Analyzer (ORA) before and after photorefractive keratectomy (PRK). METHODS: In this prospective interventional study, a total of 53 patients (53 eyes) were included. Measurements were acquired using both the Corvis-ST and ORA devices before and 3 months post- PRK. The agreement between the two devices was evaluated using limits of agreement (LoA) and Bland-Altman plots. RESULTS: The participants had a mean age of 29.6±5.21 years (range: 21 to 40), with 41 (77.4%) of them being female. Following the surgery, the average change in IOP was 0.3±1.7 mmHg for bIOP and -1.6±4.0 mmHg for IOPcc. The corresponding 95% LoA were -3.5 to 4.2 mmHg and -9.5 to 6.3 mmHg, respectively. The 95% LoA between bIOP and IOPcc after PRK was -2.3 to 8.5 mmHg. Notably, the bIOP values were higher for IOPs <20 mmHg and lower for IOPs >20 mmHg compared to IOPcc. CONCLUSIONS: The findings indicate a weak agreement between the Corvis ST-bIOP and the ORA- IOPcc both before and after PRK. These devices may not be used interchangeably for IOP measurement. bIOP exhibited less variation compared to the IOPcc, suggesting that the bIOP is a superior option for IOP reading following PRK.

Agreement of ocular response analyzer cornea compensated IOP with corvis ST biomechanical IOP following Femtosecond Laser-assisted LASIK.

OBJECTIVES: To compare intraocular pressure (IOP) measurement by ORA-IOPcc and Corvis-bIOP after femtosecond laser-assisted LASIK (FS-LASIK). METHODS: In this prospective cohort study, 56 eyes from 56 consecutive patients scheduled for FS-LASIK were enrolled. All patients had IOP measurement with ORA and Corvis ST by two blinded independent expert examiners. IOP examinations were conducted between 8 and 11 A.M. Data were collected at baseline and 3 months after FS-LASIK. RESULTS: The mean age of the participants was 29.1 ± 6.3 years, and 42 (75%) were female. The average of central corneal thickness (CCT) decreased from 537 ± 23 µm at baseline to 458 ± 31 µm after FS-LASIK. The mean postoperative change of IOP was 0.0 ± 2.1 for bIOP and -2.5 ± 3.2 mmHg for IOPcc. The corresponding 95% limits of agreement (LoA) was -4.1 to 4.1 mmHg and -3.8 to 8.8 mmHg, respectively. Both methods showed no significant correlation between ∆IOP and ∆CCT. The 95% LoA between bIOP and IOPcc after FS-LASIK was -4.8 to 9.1 mmHg. CONCLUSIONS: Compared to the ORA-IOPcc, the Corvis-bIOP showed less variation after FS-LASIK and might be a more appropriate choice for measuring IOP in this condition. The agreement of bIOP vs. IOPcc after FS-LASIK is below the clinically acceptable level, and the two methods could not be regarded as interchangeable.

Angle κ and its effect on the corneal elevation maps in refractive surgery candidates.

PURPOSE: To assess the associations of angle κ and Pentacam decentration indices with elevation maps in normal refractive surgery candidates. SETTING: Salouti Cornea Research Center, Salouti Eye Clinic, Shiraz, Iran. DESIGN: Retrospective observational study. METHODS: In this research, the right eyes of 173 refractive surgery candidates were assessed. Data of front and back corneal elevation maps, keratometric data, decentration indices, and corneal astigmatism obtained by Pentacam HR system and angle κ obtained by Orbscan IIz were extracted. Maximum elevation (or depression) for each of the 4 quadrants was recorded. Correlations of elevation values with angle κ, Pentacam decentration indices, keratometry, and astigmatism were examined by Pearson correlation coefficient. 148 age- and sex-matched cases with keratoconus grade 1 were selected as a positive control group, and Pentacam variables were compared between the groups. RESULTS: Overall, data from 173 eyes of 173 normal refractive surgery candidates and 148 eyes of 148 patients with keratoconus were recorded and analyzed. In normal refractive surgery candidates, the mean of angle κ was 5.32 ± 1.36 (SD) degrees. Angle κ had a positive correlation with front and back temporal elevations based on a best-fit sphere (BFS) ( r = 0.339, P = .001; r = 0.300, P < .001, respectively). Front and back keratometric astigmatisms were positively correlated with front and back nasal and temporal elevations ( r ≥ 0.543, P < .001) and negatively correlated with superior and inferior elevations ( r ≤ -0.547, P < .001). These associations no longer existed when using best-fit toric ellipse (BFTE) for calculating elevation data. The thinnest point to vertex decentration was significantly associated with the back temporal elevation (based on the BFTE) in both normal ( r = 0.311, P < .001) and keratoconus ( r = 0.190, P = .021) eyes. CONCLUSIONS: This study showed that elevation maps obtained by the Pentacam system using BFS might be affected by both the large angle κ and corneal astigmatism, confounding the preoperative assessment of refractive surgery candidates. Using BFTE as a reference for calculating elevation data should eliminate most diagnostic issues and thus is encouraged in this context.

Inferior Spear-like Lens Opacity as a Sign of Keratoconus.

PURPOSE: To report 21 cases of typical inferior feather-shape lens opacity associated with keratoconus. METHODS: In this cross-sectional study, we evaluated the association of keratoconus with inferior feather-shape lens opacity in refractive surgery candidates. Visual acuity, demographic, refractive, and topographic characteristics of 26 eyes of 21 patients with inferior feather-shape lens opacity were evaluated in detail. Pedigree analysis was also performed to assess possible inheritance. RESULTS: Overall, 2122 out of 33,368 cases (6.4%) without lens opacity had keratoconus, while 20 out of 21 patients (95.2%) with peculiar lens opacity had definite keratoconus (P < 0.001). Lens opacity was bilateral in 5 cases (24%), and keratoconus was bilateral in all 20 patients with lens opacity. Nine eyes out of thirty-six with a complete data record (25%) had a severe keratoconus and underwent deep lamellar keratoplasty, while 11 (31%) had forme fruste keratoconus. Pedigrees were drawn for eight patients, most families of whom suggested an X-linked recessive inheritance. CONCLUSION: The present study was the first to investigate patients with a peculiar inferior feather-shape lens opacity accompanied by bilateral keratoconus, which was observed in 95% of the patients. This finding should raise awareness as to the possibility of diagnosing keratoconus in the eyes of the patients with these characteristics.

Effect of photorefractive keratectomy on agreement of anterior segment variables obtained by a swept-source biometer vs a Scheimpflug-based tomographer.

PURPOSE: To evaluate agreement of anterior segment variables between Pentacam-AXL and IOLMaster 700 before vs after photorefractive keratectomy (PRK). SETTING: Salouti Eye Clinic, Shiraz, Iran. DESIGN: Prospective cohort with interdevice agreement analysis. METHODS: This study included healthy PRK candidates who were assessed with both devices preoperatively and 6 months after PRK. Only data from the right eye of each patient was analyzed. Pentacam-AXL average keratometry (AvgK) and zonal keratometry in the central 2.5 mm zone (zonal-K2.5) were each compared with mean keratometry (Km) from the IOLMaster 700. Other main outcome measures included vector analysis of corneal astigmatism (J0 and J45), central corneal thickness (CCT), anterior chamber depth (ACD), and white-to-white (WTW) distance. Axial length (AL) measurements by the same devices on a new cohort of 40 patients who had undergone PRK were also assessed. A paired t test was used to assess the interdevice measurement differences, and Bland-Altman analysis was used to calculate the 95% limits of agreement (LoA). RESULTS: This study included 97 patients. Preoperative vs post-PRK 95% LoAs between Pentacam-AXL and IOLMaster 700 were as follows: AvgK/Km (-0.42, 0.08 diopter [D]) vs (-0.49, 0.18 D); zonal-K2.5/Km (-0.40, 0.32 D) vs (-0.57, 0.74 D); J0 (-0.33, 0.18 D) vs (-0.28, 0.35 D); J45 (-0.28, 0.23 D) vs (-0.24, 0.27 D); pupil pachymetry/CCT (-18, 12 µm) vs (-2.6, 19.6 µm); apical pachymetry/CCT (-17.4, 12.8 µm) vs (-1.7, 20.9 µm); ACD (-0.03, 0.13 mm) vs (-0.03, 0.13 mm); WTW (-0.68, 0.23 mm) vs (-0.63, 0.14 mm); and AL (-0.07, 0.01 mm) vs (-0.07, 0.03 mm), respectively. CONCLUSIONS: PRK showed a negative impact on interdevice agreement for CCT and corneal power measurements, whereas it did not have a significant effect on the agreement of devices for ACD, WTW, AL, and the J45 astigmatism vectoral component. For IOL power measurement in post-PRK eyes, the 2 devices could be regarded as interchangeable for measuring AL and ACD but not for keratometry readings.

Assessment of the changes in corneal biomechanical properties after collagen cross-linking in patients with keratoconus.

PURPOSE: To assess the changes in biomechanical properties of the cornea after treatment of keratoconus patients with UV-A/riboflavin corneal collagen cross-linking (CXL) using Corvis ST (Oculus, Wetzlar, Germany) and Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Inc., Buffalo, NY, USA) devices. METHODS: In this prospective, observational case series, 48 eyes from 48 consecutive patients with progressive keratoconus were enrolled. Patients with history or signs of ocular disorders other than keratoconus, previous eye surgery, systemic diseases, or inability to cooperate with any measurement device were excluded. Corvis ST and ORA images were obtained at baseline and 4 months after CXL. The primary outcome measures comprised Corvis ST corneal biomechanical factors [time of highest concavity (T), time of applanation 1 (T1), time of applanation 2 (T2), length of applanation 1 (L1), length of applanation 2 (L2), velocity of applanation 1 (V1), velocity of applanation 2 (V2), deformation amplitude (DA), peak distance (PD), and radius (R)] and the ORA parameters [corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-related IOP (IOPg), cornea-compensated IOP (IOPcc), and waveform score (WS)]. RESULTS: The mean [± standard deviation (SD)] age of patients was 20 ± 5 years, and 27 (56%) were male. At baseline, the averages of the refraction, mean keratometry, and keratometric astigmatism were -3.0 ± 1.8 diopter (D), 47.0 ± 1.8 D, and 3.5 ± 1.5 D, respectively. According to Corvis ST, L2 increased from 0.83 ± 0.25 mm at baseline to 1.15 ± 0.57 mm after CXL; and V2 decreased from -0.81 ± 0.08 to -0.94 ± 0.26 m/s (P = 0.001 and P = 0.032, respectively). ORA parameters showed significant decrease in the CRF (from 7.82 ± 1.72 to 7.21 ± 1.05 mmHg; P = 0.036) and increase in the WS (from 4.58 ± 2.55 to 6.12 ± 1.92; P = 0.002). CONCLUSIONS: According to in vivo observation with Corvis ST and ORA, CXL induces significant changes in corneal biomechanical properties in cases with keratoconus. The parameters with significant changes (L2 and V2) may reflect increased stiffness of the treated cornea. The importance of such observations should be elucidated in future studies.

A Population-Based Study on the Prevalence and Risk Factors of Chronic Kidney Disease in the Adult Population of Shiraz, Southern Iran.

BACKGROUND: Currently, we are facing a significant increase in the new cases of the end-stage renal disease in developing countries. Hence, it seems vital to work on strategies aimed at reducing its development and progression. Determining the related risk factors can provide an insight into achieving these policymaking goals. Therefore, this study was conducted to identify risk factors associated with chronic kidney disease (CKD) in the Iranian adult population. MATERIALS AND METHODS: This cross-sectional study was performed in Shiraz, Southern Iran, through a cluster random sampling technique that involved 819 subjects, including 340 male and 479 female adult participants. Factors such as the body mass index, waist circumference, blood pressure, and biochemical profile were determined. We evaluated the prevalence of CKD according to the glomerular filtration rate (GFR), as well as possible risk factors associated with it. GFR was calculated on the basis of the "Chronic Kidney Disease Epidemiology Collaboration" creatinine equation. RESULTS: The cluster comprised 58.5% females and 41.5% males. The mean age of our participants was 43.0 ± 14.0 years. Our results showed that 16.6% of adult urban inhabitants in Iran had CKD (stages 3 to 5, eGFR ≤60), that is, GFR less than 60 mL/min/1.73 m2. The proportion of participants having hypertension, obesity, high waist circumference, diabetes mellitus, and history of cardiovascular disease was 17.3%, 19.3%, 35%, 9.4%, and 5.3%, respectively. Multiple regression analysis indicated an independent correlation between age, sex, dyslipidemia, and hypertension with CKD. CONCLUSION: This study indicates that CKD is a substantial health burden in Iranian adult population. Additionally, the results of this study addressed the importance of integrated strategies that aimed to identify, prevent, and treat noncommunicable diseases fueling the development of CKD.

Comparison between manual trephination versus femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus.

BACKGROUND/AIMS: To compare the outcomes of femtosecond laser-assisted deep anterior lamellar keratoplasty (F-DALK) versus manual trephination DALK (M-DALK) in patients with keratoconus. METHODS: In this retrospective, comparative, clinical study, medical charts of 860 patients with keratoconus who underwent F-DALK (n=391) or M-DALK (n=469) with the Melles's technique, and had at least a 12-month follow-up record were reviewed. The main outcome measures comprised best spectacle-corrected visual acuity (BSCVA), manifest refraction and keratometric indices. The postsurgical measurements were recorded for all patients at 12 months (suture-in condition), and a subset of patients with complete data at 24 months (suture-out condition; 111 F-DALK and 282 M-DALK cases). RESULTS: Both procedures had comparable mean (±SD) logMAR BSCVA at 12 months (0.18±0.12 for M-DALK and 0.17±0.12 for F-DALK; p=0.224) and 24 months (0.11±0.10 vs 0.09±0.09, respectively; p=0.166) examinations. M-DALK was associated with a significant more residual myopia at 12 months (-3.85±3.27 vs -1.94±2.86 D; p<0.001), and a milder similar trend at 24 months follow-up (-2.94±2.72 vs -2.38±2.65 D, p=0.064). The mean keratometry (12 months: 46.15±1.88 vs 44.39±1.72, p<0.001; 24 months: 45.33±2.37 vs 44.14±1.68, p<0.001) and apical keratometry values (12 months: 50.92±5.00 vs 47.13±2.38, p<0.001; 24 months: 50.29±4.25 vs 48.12±3.81) were significantly greater for M-DALK than F-DALK, while the keratometric astigmatism was similar (12 months: 2.62±1.58 vs 2.53±1.33, p=0.364; 24 months: 3.21±1.83 vs 3.34±1.88, p=0.529). CONCLUSIONS: F-DALK for advanced keratoconus performs as well as M-DALK in terms of BSCVA and keratometric astigmatism in both suture-in (12 months) and suture-out (24 months) conditions. It might have advantages over M-DALK for residual myopia and restoring corneal anatomy.

Agreement of Corneal Diameter Measurements Obtained by a Swept-source Biometer and a Scheimpflug-based Topographer.

PURPOSE: To assess the agreement between a swept-source optical biometry device (IOLMaster 700) and a Scheimpflug-based topography device (Pentacam HR) in measuring the corneal diameter. METHODS: A total of 100 eyes from 100 cataract surgery candidates were enrolled. The white-to-white (WTW) distance measurements provided by both devices were recorded and analyzed. A paired t test was performed to compare the mean values of the WTW distance between the IOLMaster 700 and Pentacam HR. The Bland-Altman analysis was used to evaluate the agreement between the measurements of both devices. RESULTS: Mean age (±SD) of the participants was 65.9 ± 3.3 years, and 58 (58%) were men. The mean WTW distances measured by the IOLMaster 700 and Pentacam HR were 11.72 ± 0.45 mm and 11.41 ± 0.42 mm, respectively (P < 0.001). The overall 95% limits of agreement were -0.17 and 0.78 mm. The 95% limits of agreement between the measurements of the 2 devices were -0.30 and 0.84 versus -0.07 and 0.72 for eyes with WTW distances of ≤11.50 mm versus >11.50 mm, respectively. CONCLUSIONS: According to the results of this study, the IOLMaster 700 may overestimate the WTW distance measurements by up to 0.78 mm compared with the Pentacam HR, so these 2 devices should not be used interchangeably for this purpose. The agreement is somehow weaker for eyes with WTW distances of 11.50 mm or less than those with WTW distances greater than 11.50 mm.

Deep anterior lamellar keratoplasty for keratectasia after laser in situ keratomileusis.

PURPOSE: To assess the efficacy of deep anterior lamellar keratoplasty (DALK) for treating post-LASIK keratectasia. SETTING: Poostchi Eye Research Center, Shiraz University of Medical Sciences, Shiraz, Iran. DESIGN: Retrospective interventional cases series. METHODS: The same surgeon performed all DALK procedures using the Melles manual technique. The preoperative and postoperative corrected distance visual acuity (CDVA), spherical equivalent (SE) refraction, keratometry (K) readings, and endothelial cell profiles were compared. RESULTS: The cohort comprised 20 eyes of 18 patients (72% women) with a mean age of 29 years ± 4 (SD). The mean follow-up was 31.8 ± 17.0 months (range 6 to 60 months). The mean Snellen CDVA improved significantly from 20/191 before DALK to 20/23 after DALK (P < .001). The mean of the modulus of SE refraction was 11.9 ± 6.6 diopters (D) and 11.4 ± 4.3 D, respectively (P = .446). The mean K value was 52.2 ± 7.0 D before DALK and 46.0 ± 1.9 D after DALK (P = .001); the mean apical K value, 59.5 ± 5.1 D and 49.9 ± 2.8 D, respectively (P < .001); and the mean keratometric astigmatism, 4.3 ± 2.4 D and 1.9 ± 1.2 D, respectively (P = .003). The endothelial cell profile did not change significantly, and no major complications related to DALK occurred. Twelve eyes had additional refractive procedures to correct residual ametropia. CONCLUSION: Deep anterior lamellar keratoplasty using the Melles manual technique was effective and safe in restoring CDVA in patients with post-LASIK keratectasia; however, high residual ametropia was a common finding.

Changes in corneal endothelial cell profile measurements after deep anterior lamellar keratoplasty for keratoconus.

PURPOSE: The primary objective was to evaluate whether postoperative alterations in corneal shape (as reflected by keratometry values) affect endothelial cell profile measurements after deep anterior lamellar keratoplasty (DALK) in a group of patients with keratoconus. Secondary objective was to describe the pattern of changes in corneal endothelial cell profile measurements during the first 3 years after DALK. METHODS: In this prospective interventional case series, we enrolled patients who had significant keratoconus and were scheduled for DALK (Melles technique). Cases with concomitant intraocular surgeries, intra-/postoperative complications, and poor quality of images were excluded. RESULTS: Two hundred one eyes and 45 eyes (of the original 201) were enrolled for evaluating the primary and the secondary objectives, respectively. At 3 months post DALK, the mean endothelial cell density (ECD) had significantly increased and the mean cell area had decreased compared with preoperative measurements (2721 vs. 2823 cells/mm2, P = 0.015; and 378 vs. 362 µm2, P = 0.005, respectively). Regression analysis revealed a weak but significant nonlinear association between changes in mean keratometry and ECD changes at 3 months (R2 = 0.039, P = 0.02). Standard deviation of mean cell area had significantly decreased at 12 months after DALK compared with measurements taken at 3 months after surgery (P = 0.023) and remained stable thereafter. CONCLUSIONS: Apparent measurements of ECD may not show a decrease but instead even a slight increase in some cases after uncomplicated DALK (Melles technique) for keratoconus. This finding along with a later decrease in standard deviation of mean cell area suggests that notable postoperative changes in corneal biomechanical forces may affect endothelial cell profile measurements.

Comparison of Horizontal corneal diameter measurements using the Orbscan IIz and Pentacam HR systems.

PURPOSE: To compare 2 automated devices for measuring the horizontal corneal diameter [white-to-white (WTW) distance]. METHODS: In this prospective comparative case series, the WTW distance was measured by independent examiners using the Pentacam HR and the Orbscan IIz in 101 eyes of 101 healthy refractive surgery candidates. Statistical evaluation was performed using the paired t test, Pearson correlation, and the Bland-Altman method for comparison of measurement techniques. RESULTS: The mean WTW distance measurements were 11.76 ± 0.38 mm as obtained with the Pentacam HR and 11.66 ± 0.37 mm as obtained with the Orbscan IIz (P < 0.001). The measurements were highly correlated (Pearson correlation coefficient = 0.948; P < 0.001). The 95% limits of agreement for the Pentacam HR versus the Orbscan IIz were -0.14 to 0.33 mm. CONCLUSIONS: The observed differences in WTW distance readings between the Pentacam HR and the Orbscan IIz are not clinically relevant, and the 2 devices could be used interchangeably in clinical practice.

Comparison of the ultrasonographic method with 2 partial coherence interferometry methods for intraocular lens power calculation.

BACKGROUND: The accuracy of biometric measurements, particularly axial length, is critical for precise intraocular lens (IOL) power calculation and predictable refractive outcomes after cataract surgery. Partial coherence interferometry-based systems represent progress toward measurements that are more precise and reliable. The purpose of this study was to evaluate a new noncontact optical biometer (Lenstar; Haag-Streit AG, Koeniz, Switzerland) using optical low-coherence reflectometry and to compare the biometric measurements (including axial length, keratometry, anterior chamber depth, and IOL power) with those obtained from current clinical instrumentation. METHODS: Biometric measurements were obtained with Lenstar, IOL Master V.5 (Carl Zeiss Meditec AG, Jena, Germany), and A-scan applanation ultrasound scan combined with a Javal-type keratometer in 234 eyes of 234 subjects scheduled for cataract surgery. IOL power was calculated using Sanders, Retzlaff, Kraff II, Hoffer Q, and Holladay 1 formulas. RESULTS: The axial length readings were similar (P = 0.997). The anterior chamber depth measurements obtained by IOL Master were slightly smaller than those obtained with other devices (P = 0.092). The means of the average keratometry readings were 0.65 and 0.61 diopters lower when measured with Lenstar as compared with IOL Master and the Javal-type keratometer, respectively (P = 0.002). All of the measurements were tightly correlated (P < 0.001). For anterior chamber depth measurements, however, the correlation was slightly weaker. Using the above-mentioned formulas, the mean IOL power measurements were similar. These measurements were tightly correlated (P < 0.001). The level of agreement was acceptable and comparable between devices. CONCLUSIONS: The findings from this study show the validity and clinical utility of Lenstar compared with instrumentation currently used in clinical practice for assessing ocular biometry and IOL power calculation in cataractous eyes.

Comparison of anterior chamber depth measurements using Galilei, HR Pentacam, and Orbscan II.

BACKGROUND: Anterior chamber depth measurement is used frequently in cataract and refractive surgery for advanced intraocular lens (IOL) power calculation formulas and implantation of phakic IOLs. In this article, we show agreement in anterior chamber depth measurements in normal eyes among 3 noncontact systems, namely Galilei, HR Pentacam, and Orbscan II. METHODS: The anterior chamber depth measurements were obtained with Galilei, HR Pentacam, and the Orbscan II in both eyes of 37 healthy subjects. Pearson's correlations were calculated, and mean anterior chamber depth measurements were compared. Bland-Altman plots were used to assess the difference between individual measurements for each patient. RESULTS: The mean anterior chamber depth readings (+/- standard error of means) with Galilei, Pentacam, and Orbscan were 3.22 +/- 0.05, 3.25 +/- 0.05, and 3.54 +/- 0.07, respectively. The difference between Galilei and Pentacam was not statistically significant (P = 0.013). However, Orbscan measurements were larger than those of either Galilei or Pentacam (P < 0.001). The differences between Orbscan and either Galilei or Pentacam were increased with greater anterior chamber depths. The 95% limits of agreement between Orbscan and Galilei, Orbscan and Pentacam, and Pentacam and Galilei in different ranges of chamber depth were ([ < 3 mm, -0.43 to +0.71 mm]; [3 to 3.5 mm, -0.23 to +0.83]; [ > 3.5 mm, +0.41 to +0.53]), ([ < 3 mm, -0.43 to +0.71 mm]; [3 to 3.5 mm, -0.26 to +0.80]; [ > 3.5 mm, +0.38 to +0.54]), and ([ < 3 mm, -0.05 to +0.06 mm]; [3 to 3.5 mm, -0.06 to +0.10]; [ > 3.5 mm, -0.11 to +0.12]), respectively. CONCLUSIONS: These data indicate that in the assessment of normal eyes, Orbscan gives consistently higher measurements for anterior chamber depth compared with Galilei and Pentacam. Because the differences between Orbscan and either Galilei or Pentacam were not within clinically acceptable levels, they are not interchangeable in every clinical situation. However, the differences among anterior chamber depth values measured with Galilei and Pentacam were within clinically acceptable levels. Thus, these 2 systems can be regarded as interchangeable.

Comparison of horizontal corneal diameter measurements using Galilei, EyeSys and Orbscan II systems.

BACKGROUND: White-to-white corneal measurement is used frequently in cataract and refractive surgery as well as in diagnosing various corneal diseases and monitoring congenital glaucoma. In this article, we determine agreement in horizontal corneal diameter measurements in normal eyes among the Galilei V4.01, the EyeSys and the Orbscan IIz. METHODS: In this prospective study, 37 consecutive volunteers were enrolled. All 74 eyes were measured with all three devices. Galilei, EyeSys and Orbscan II measurements were compared with one another. In addition, the data from the right and left eyes were compared for each device. RESULTS: The mean horizontal corneal diameter measurements with the Galilei, the EyeSys and the Orbscan II were 12.01 +/- 0.61 mm, 12.09 +/- 0.87 mm and 11.67 +/- 0.29 mm, respectively. The difference between the Galilei and EyeSys systems was not statistically significant (p = 0.76), however, the Orbscan II showed smaller measurements (p < 0.001). The best 95% limits of agreement between devices were for the Galilei and the Orbscan II (-0.72, 1.48; r = 0.4, p < 0.01). The best 95% limits of agreement between two eyes for each device were found with the Orbscan II (-0.15, 0.17; r = 0.996, p < 0.01). There was no correlation between measurements of right and left eyes for the Galilei or the EyeSys (r = 0.274, p = 0.176 and r = 0.31, p = 0.065, respectively). CONCLUSIONS: These results suggest that measurements made with the Orbscan II are smaller than those obtained with the EyeSys Corneal Analysis system and the Galilei. Among the three devices, the Galilei and the Orbscan II showed the best agreement, however, it is inadvisable to use the three devices interchangeably in every clinical situation.