New Non-contact Tonometer HNT-1P Reliability: Comparing Intraocular Pressure, Central Corneal Thickness, and Corrected Intraocular Pressure

Purpose@#To assess the reliability of a new non-contact tonometer, HNT-1P, by comparing its intraocular pressure (IOP), central corneal thickness (CCT), and corrected IOP (cIOP) measurements with the IOP measured by Goldmann applanation tonometry (GAT), the CCT measured with ultrasound pachymetry (USP), and the cIOP derived from GAT IOP and USP CCT. @*Methods@#A total of 120 eyes of 65 healthy or glaucoma suspects were included in this study. The IOP was measured with the HNT-1P and GAT. The CCT was determined using the HNT-1P and USP. The IOP measured with GAT was corrected according to the CCT measured by USP. The correlations of the measurements obtained with the various instruments were evaluated using Pearson’s correlation coefficient, and the agreement was assessed using Bland-Altman plots. @*Results@#The average IOP measured with the HNT-1P and GAT was 14.8 ± 5.1 mmHg and 15.6 ± 5.2 mmHg, respectively, and the correlation coefficient between the two IOP measurements was 0.964 (p < 0.001). The mean CCT was 553.5 ± 27.4 μm using the HNT-1P and 550.6 ± 26.3 μm using USP, and the correlation coefficient between the two measurements was 0.913 (p < 0.001). The average cIOP was 14.6 ± 5.0 and 13.4 ± 6.5 mmHg according to the HNT-1P and GAT, respectively, and the correlation coefficient between the two corrected measurements was 0.956 (p < 0.001). Bland-Altman plots showed a high degree of agreement between the HNT-1P measurements and those of the other devices. @*Conclusions@#The new non-contact HNT-1P tonometer provided reliable IOP, CCT, and cIOP measurements when compared with GAT and USP. HNT-1P could therefore be used clinically for reliable and accurate measurements of the IOP, CCT, and cIOP.

Progressive Optic Disc Tilt in Young Myopic Glaucomatous Eyes

PURPOSE: To explore the progressive change and associated factors of optic disc tilt in young myopic glaucomatous eyes by analyzing long-term follow-up data.METHODS: Optic disc images were obtained from spectral-domain optical coherence tomography enhanced depth imaging from at least five different visits. At each visit, the disc tilt angle (DTA), defined as the angle between the Bruch's membrane opening plane and the optic canal plane, was estimated at the central frame that passes through the optic disc. Glaucoma progression was assessed on the basis of changes noted on serial optic disc and retinal nerve fiber layer photographs or changes in the visual field (VF). A linear mixed effect model was used to assess the influence of parameters (age, sex, baseline and follow-up intraocular pressure, retinal nerve fiber layer thickness, VF mean deviation, axial length, central corneal thickness), and presence of glaucomatous progression upon DTA change.RESULTS: A total of 26 eyes of 26 young myopic primary open-angle glaucoma patients (axial length >24.0 mm; mean age, 25.1 ± 4.0 years; mean follow-up, 3.3 ± 0.9 years) were included. DTA was 7.0 ± 3.4 degrees at baseline and 8.3 ± 3.8 degrees at last visit, which represents a significant difference (p < 0.001). Worse VF mean deviation (p < 0.001) and longer axial length (p = 0.006) were significantly associated with DTA increase.CONCLUSIONS: Young myopic glaucomatous eyes showed progressive optic disc tilting. Progressive optic disc tilting in young myopic glaucomatous eyes may be related to either continuous axial myopic shift or glaucomatous structural change.

Relationship between Progressive Changes in Lamina Cribrosa Depth and Deterioration of Visual Field Loss in Glaucomatous Eyes

PURPOSE: To investigate the relationship between the progression of visual field (VF) loss and changes in lamina cribrosa depth (LCD) as determined by spectral-domain optical coherence tomography (SD-OCT) enhanced depth imaging in patients with primary open angle glaucoma (POAG). METHODS: Data from 60 POAG patients (mean follow-up, 3.5 ± 0.7 years) were included in this retrospective study. The LCD was measured in the optic disc image using SD-OCT enhanced depth imaging scanning at each visit. Change in the LCD was considered to either ‘increase’ or ‘decrease’ when the differences between baseline and the latest two consecutive follow-up visits were greater than the corresponding reproducibility coefficient value (23.08 µm, as determined in a preliminary reproducibility study). All participants were divided into three groups: increased LCD (ILCD), decreased LCD (DLCD), and no LCD change (NLCD). The Early Manifest Glaucoma Trial criteria were used to define VF deterioration. Kaplan-Meier survival analysis and Cox's proportional hazard models were performed to explore the relationship between VF progression and LCD change. RESULTS: Of the 60 eyes examined, 35.0% (21 eyes), 28.3% (17 eyes), and 36.7% (22 eyes) were classified as the ILCD, DLCD, and NLCD groups, respectively. Kaplan-Meier survival analysis showed a greater cumulative probability of VF progression in the ILCD group than in the NLCD (p < 0.001) or DLCD groups (p = 0.018). Increased LCD was identified as the only risk factor for VF progression in the Cox proportional hazard models (hazard ratio, 1.008; 95% confidence interval, 1.000 to 1.015; p = 0.047). CONCLUSIONS: Increased LCD was associated with a greater possibility of VF progression. The quantitative measurement of LCD changes, determined by SD-OCT, is a potential biomarker for the prediction of VF deterioration in patients with POAG.

Effects of Choroidal Thickness on Refractive Outcome Following Cataract Surgery in Primary Angle Closure

PURPOSE: To identify the preoperative biometric factors, including subfoveal choroidal thickness (CT), associated with refractive outcome after cataract surgery in eyes with primary angle closure (PAC). METHODS: This study included 50 eyes of 50 PAC patients who underwent uneventful cataract surgery. Preoperatively, anterior segment parameters including anterior chamber depth (ACD) and lens vault were determined by anterior segment optical coherence tomography. Subfoveal CT was measured by spectral domain optical coherence tomography enhanced depth imaging before and at one month after surgery. Mean refractive error (MRE) was calculated as the difference in spherical equivalent between actual postoperative refraction determined one month postoperatively and that predicted using each of three IOL calculation formulas (SRK/II, SRK/T, and Haigis). Regression analyses were performed to investigate potential associations between MRE and putative factors. RESULTS: Mean ACD was 1.9 ± 0.4 mm, and preoperative subfoveal CT was 250.8 ± 56.9 µm. The SRK/T (MRE, 0.199 ± 0.567 diopters [D]) and Haigis (MRE, 0.190 ± 0.727 D) formulas showed slight hyperopic shift, while the SRK/II formula demonstrated a myopic shift (MRE, −0.077 ± 0.623 D) compared with that expected after cataract surgery. Mean absolute refractive error was not significantly different between formulas. Higher preoperative lens vault and shallower ACD were associated with a hyperopic shift in all formulas, but not in a statistically significant manner. Thicker preoperative subfoveal choroid was associated with a myopic shift after cataract surgery in all formulas (SRK/II: β = −0.511, p < 0.001; SRK/T: β = −0.652, p < 0.001; Haigis: β = −0.671, p < 0.001). Greater postoperative reduction of subfoveal CT was associated with a myopic shift after cataract surgery in all formulas (SRK/II: β = −0.511, p < 0.001; SRK/T: β = −0.652, p < 0.001; Haigis: β = −0.671, p < 0.001). CONCLUSIONS: Our results indicate that preoperative subfoveal CT and the difference between pre- and postoperative subfoveal CT are significant factors for predicting refractive error after cataract surgery in PAC patients. These findings should be considered when performing cataract surgery to optimize visual outcomes.

Retinal Nerve Fiber Layer Volume Measurements in Normal Children Using Spectral Domain Optical Coherence Tomography

PURPOSE: To measure retinal nerve fiber layer (RNFL) volume in normal children using spectral domain optical coherence tomography (SD-OCT). METHODS: This study included 79 eyes of 54 normal children between 4 and 15 years of age evaluated from February 2012 to November 2012. All participants underwent ocular examination and 3D-disc scanning using SD-OCT. RNFL volume was calculated between 2.5 and 5 mm diameter circles using the length, width, and height of each pixel derived from the RNFL thickness map with Matlab software. The relationship between RNFL volume and thickness was analyzed. RESULTS: The RNFL volumes of the mean total, superior, nasal, inferior, and temporal areas were 1.48 ± 0.09 mm3, 0.45 ± 0.04 mm3, 0.29 ± 0.04 mm3, 0.46 ± 0.03 mm3, and 0.29 ± 0.04 mm3, respectively. Comparing RNFL volume and conventional circumpapillary RNFL thickness measured using built-in software, a strong correlation between mean total, superior, and inferior areas (R = 0.980, 0.953 and 0.932, respectively) and a moderate correlation between the nasal and temporal areas were observed (R = 0.545 and 0.514, respectively). The negative correlations between RNFL thickness and RNFL volumes of the mean total, superior, nasal, inferior, and temporal areas and age were not significant (p > 0.05). CONCLUSIONS: This study reports RNFL volume measured from RNFL thickness map analysis in normal children. These data regarding RNFL volume of normal children may provide useful information for diagnosis and monitoring of pediatric glaucoma.

Usefulness of Automated Measurements of Localized Retinal Nerve Fiber Layer Defects Area Using Significance Map

PURPOSE: To evaluate the usefulness of automated measurements of the localized retinal nerve fiber layer (RNFL) defects area in patients with glaucoma. METHODS: Fifty one patients with localized RNFL defects in RNFL red-free photographs and 53 healthy subjects were included. All participants were imaged with 3D spectral-domain optical coherence tomography (OCT). The area of defects was measured with the RNFL significance map (red = p < 1% and yellow = p < 5%) using Image J manually and Matlab software automatically. The area under the receiver operating characteristic curve (AUC) was calculated for the RNFL defect area of the RNFL photograph and RNFL maps, circumpapillary RNFL thickness, optic disc parameter, and macular inner retina thickness. RESULTS: High correlation was observed between manually and automatically measured defect areas in the significance map (red area r = 0.904, red and yellow area r = 0.890). The AUC for manually and automatically measured defects area (0.987, 0.966; p < 5%, p = 0.31, respectively) in the significance map was comparable. The latter demonstrated slightly higher but insignificant difference in AUC for inferior quadrant circumpapillary RNFL thickness (0.936; p = 0.22) and was significantly higher than the inferior ganglion cell layer plus inner plexiform layer thickness (0.894) and vertical cup to disc ratio (0.869) (p = 0.018, p = 0.008, respectively). CONCLUSIONS: The automated measurements of the RNFL defect area in the significance map performed adequately in detecting localized RNFL defects and had a better performance than macular inner retina and optic nerve parameters.

Comparison of Diagnostic Ability of 3D and Stratus Optical Coherence Tomography in Early Glaucoma

PURPOSE: To compare the ability of three dimensional spectral-domain optical coherence tomography (3D OCT) and Stratus OCT to detect early glaucoma. METHODS: The optic disc topographic and retinal nerve fiber layer (RNFL) thickness parameters were measured by 3D OCT and Stratus OCT in 69 normal eyes and 48 early glaucoma eyes. The discriminating abilities of the two techniques for detection of glaucoma were compared by the area under the receiver operating characteristic curves (AUC). RESULTS: The best Stratus OCT parameters and criterion that differentiated normal from early glaucoma based on AUC were horizontal integrated rim width (0.85) for optic nerve head parameters, inferior quadrant (0.88) for RNFL parameters, and > or =1 clock-hour abnormal at the 5% level (0.81) based on the normative database for criteria. The best 3D OCT parameters and criterion that differentiated normal from early glaucoma were vertical cup-to-disc ratio (0.85), 11 o'clock RNFL thickness (0.86), and > or =1 clock-hour abnormal at the 1% level (0.78), respectively. When all corresponding the best parameters and criterion were compared, there were no significant differences between the AUCs for Stratus OCT and 3D OCT (p = 0.95, p = 0.73, p = 0.45, respectively). CONCLUSIONS: Stratus OCT and 3D OCT had similar diagnostic ability for detection of early glaucoma.

Comparison of Ocular Biometry and Postoperative Refraction in Cataract Patients Between Lenstar(R) and IOL Master(R)

PURPOSE: To compare axial length, anterior chamber depth, and keratometric measurements of an optical low-coherence reflectometry device with those of other ocular biometry devices and evaluate the accuracy of predicting postoperative refraction. METHODS: A total of 32 eyes in 32 patients who received cataract surgery were included in the present study. The axial length, anterior chamber depth, and keratometry were measured by optical low-coherence reflectometry (Lenstar LS900(R)), partial coherence interferometry (IOL master(R)), and ultrasound. The SRK/T formula was used to calculate IOL power, and predictive error that subtracts predictive refraction from postoperative refraction was compared among ocular biometry devices. RESULTS: Axial length, anterior chamber depth, and keratometry had a strong correlation and demonstrated no statistically significant differences between Lenstar LS900(R) and other devices. The Bland-Altman plots showed a high degree of agreement between Lenstar LS900(R) and other devices. The mean absolute prediction errors in Lenstar LS900(R) and IOL master(R) were not significantly different. CONCLUSIONS: The ocular biometric measurements and prediction of postoperative refraction using Lenstar LS900(R) were as accurate as IOL master(R) and ultrasound.

Measurement of Choroidal Thickness in Normal Eyes Using 3D OCT-1000 Spectral Domain Optical Coherence Tomography

PURPOSE: To study choroidal thickness and its topographic profile in normal eyes using 3D OCT-1000 spectral domain optical coherence tomography and the correlation with age and refractive error. METHODS: Fifty-seven eyes (45 individuals) with no visual complaints or ocular disease underwent horizontal and vertical line scanning using 3D OCT-1000. The definition of choroidal thickness was the vertical distance between the posterior edge of the hyper-reflective retinal pigment epithelium and the choroid/sclera junction. Choroidal thickness was measured in the subfoveal area at 500 microm intervals from the fovea to 2,500 microm in the nasal, temporal, superior, and inferior regions. The spherical equivalent refractive error was measured by autorefractometry. Statistical analysis was used to confirm the correlations of choroidal thickness with age and refraction error. RESULTS: The mean age of the 45 participants (57 eyes) was 45.28 years. Detailed visualization of the choroid for measuring its thickness was possible in 63.3% of eyes. The mean subfoveal choroidal thickness was found to be 270.8 microm (standard deviation [SD], +/-51 microm), in horizontal scanning and 275.0 microm (SD, +/-49 microm) in vertical scanning. The temporal choroidal thickness was greater than any 500 microm interval in corresponding locations, and there was no significant difference between the superior and inferior choroid as far as 2,000 microm from the fovea. Age and refractive error were associated with subfoveal choroidal thickness in terms of regression (p < 0.05). CONCLUSIONS: Choroidal thickness in normal Korean eyes can be measured using 3D OCT-1000 with high resolution line scanning. The topographical profile of choroidal thickness varies depending on its location. Age and refractive error are essential factors for interpretation of choroidal thickness.

Optic Disc Pit with Peripapillary Retinoschisis Presenting as a Localized Retinal Nerve Fiber Layer Defect

A 59-year-old woman was referred to our clinic for a glaucoma evaluation. The visual acuity and intraocular pressure were normal in both eyes. However, red-free fundus photography in the left eye showed a superotemporal wedge-shaped retinal nerve fiber layer defect, and visual field testing showed a corresponding partial arcuate scotoma. In an optical coherence tomography examination, the macula was flat, but an arcuate-shaped peripapillary retinoschisis was found. Further, the retinoschisis seemed to be connected with a superotemporal optic pit shown in a disc photograph. After 3 months of a topical prostaglandin analogue medication, the intraocular pressure in the retinoschisis eye was lowered from 14 to 10 mmHg and the peripapillary retinoschisis was almost resolved. We report a rare case of an optic disc pit with peripapillary retinoschisis presenting as a localized retinal nerve fiber layer defect.