Objective To evaluate changes in peripapillary and macular choroidal thickness and volume after the water-drinking test (WDT) using swept-source optical coherence tomography (SS-OCT). Design Prospective, cross-sectional observational study. Participants Fifty-six eyes of 28 healthy volunteers. Methods Participants underwent a 3-dimensional optic disc and macula scanning protocol with a prototype SS-OCT (Topcon Inc., Tokyo, Japan) at baseline and 15, 30, 45, and 120 minutes after the start of the WDT. The WDT consisted of drinking 1000mL of water within five minutes. Objective measurements of the choroid were obtained with automated segmentation of the choroidal boundaries. Main Outcome Measures Choroidal thickness and volume. Results Mean (standard deviation) age of participants was 35.6 ± 9.1 years. Intraocular pressure (IOP) increased from 14.9 ± 2.7 mmHg at baseline to a peak of 16.8 ± 3.0 mmHg at 15 minutes after the WDT (p<0.001). Mean baseline choroidal thickness and volume were 181.3 ± 50.8 μm and 6.19 ± 1.80 mm3 at the optic disc and 217.4 ± 43.6 μm and 7.83 ± 1.55 mm3 at the macula. Following the WDT, peripapillary and macular choroidal thickness increased by a maximum of 5.7% (P < 0.001) and 4.3% (P < 0.001) respectively. Choroidal volumes increased by 6.4% (P < 0.001) and 3.9% (P < 0.001), respectively. There was no association between change in IOP and peripapillary (P = 0.27) or macular (P = 0.09) choroidal thickness. Conclusions Using automated segmentation of SS-OCT measurements, significant increases in choroidal thickness and volume are observed after the WDT in healthy subjects.

Optical coherence tomography (OCT) is increasingly used to obtain objective measurements of the retinal nerve fiber layer (RNFL), optic nerve head, and macula for assessing glaucoma progression. Although OCT has been adopted widely in clinical practice, uncertainty remains concerning its optimal role. Questions include: What is the best structure to measure? What quantity of change is significant? Are structural changes relevant to the patient? How are longitudinal measurements affected by aging? How can changes resulting from aging be differentiated from true progression? How best should OCT be used alongside visual fields, and how often should OCT be performed? Recent studies have addressed some of these questions. Important developments include appreciation of the need to use a consistent point of reference for structural measurements, leading to the introduction of Bruch's membrane opening (BMO)-based measurements, including BMO-minimum rim width and BMO-minimum rim area. Commercially available OCT devices also permit analysis of macular changes over time, for example, changes in the ganglion cell and inner plexiform layers, the sites of the retinal ganglion cell bodies and dendrites, respectively. Several longitudinal studies have compared rates of change in RNFL and macular measurements, with some suggesting that the relative value of each parameter may differ at different stages of disease. In early disease, looking for change over time also may be useful for glaucoma diagnosis, with advantages over classifying eyes using cross-sectional normative databases. Optimal glaucoma management requires information from imaging and visual fields, and efforts have been made to combine information, reducing the noise inherent in both tests to benefit from their different performances according to the stage of disease. Combining information from different structural measurements may also be useful. There is now substantial evidence that progressive structural changes are of direct clinical relevance, with progressive changes on OCT often preceding functional loss and patients with faster change on OCT at increased risk of worsening visual losses. Identification of such patients offers the possibility of commencing or escalating treatment at an earlier stage. This review appraises recent developments in the use of OCT for assessing glaucoma progression.

Objective To determine whether focal abnormalities of the lamina cribrosa (LC) are present in glaucomatous eyes with localized retinal nerve fiber layer (RNFL) defects. Design Cross-sectional observational study. Participants 20 eyes of 14 subjects with localized RNFL defects detected by masked grading of stereophotographs and 40 eyes of 25 age-matched healthy subjects recruited from the Diagnostic Innovations in Glaucoma Study (DIGS) at the University of California, San Diego. Methods All eyes had stereoscopic optic disc photography and in vivo LC imaging using enhanced depth optical coherence tomography (EDI-OCT). Two masked graders identified focal LC defects defined by a standardized protocol using 48 radial scan EDI-OCT images. The Kappa coefficient was calculated as a measure of the reliability of interobserver agreement. Main Outcome Measures The number of focal LC defects and the relationship between the location of LC defects and the location of localized RNFL defects. Results 15 of 20 eyes with a localized RNFL defect (75%) had at least one LC defect compared to only 1 of 40 healthy eyes (3%). 13 eyes with localized RNFL defects had 1 LC defect, 1 eye had 2 LC defects and 1eye had 3 LC defects. The largest area LC defect was present in a radial line EDI-OCT scan corresponding to a localized RNFL defect in 13/15 (87%) of eyes. There was good agreement between graders as to whether an eye had a LC defect (Kappa=0.87, 95% CI 0.73–1.00, P<0.001) and the location of the largest defect (Kappa=0.72, 95% CI 0.44–1.00, P<0.001). Conclusions Focal defects of the lamina cribrosa were frequently visible in glaucomatous eyes with localized RNFL defects. Focal abnormalities of the LC may be associated with focal retinal nerve fiber damage.

Aims To evaluate the technique of eye drop instillation in patients with glaucoma and assess factors associated with a good technique. Methods A cross-sectional observational study of 85 participants using selfadministered topical medication for glaucoma or ocular hypertension. Patients were asked to demonstrate how they normally instil eye drops using a 5-ml bottle of sterile artificial tear solution. The procedure was recorded and assessed by two masked graders. Whether the patient had been previously shown how to instil drops, the number of eye medications used, and self-perceived difficulty of using drops were also recorded. Conclusions Education relating to eye drop instillation technique is significantly associated with a patient's ability to instil drops correctly. The assessment of a patient's ability to instil eye drops correctly should be a routine part of the glaucoma examination.

PURPOSE To determine the repeatability of automated retinal and choroidal thickness measurements with swept-source optical coherence tomography (SS OCT) and the frequency and type of scan artifacts. DESIGN Prospective evaluation of new diagnostic technology. METHODS Thirty healthy subjects were recruited prospectively and underwent imaging with a prototype SS OCT instrument. Undilated scans of 54 eyes of 27 subjects (mean age, 35.1 ± 9.3 years) were obtained. Each subject had 4 SS OCT protocols repeated 3 times: 3-dimensional (3D) 6 × 6-mm raster scan of the optic disc and macula, radial, and line scan. Automated measurements were obtained through segmentation software. Interscan repeatability was assessed by intraclass correlation coefficients (ICCs). RESULTS ICCs for choroidal measurements were 0.92, 0.98, 0.80, and 0.91, respectively, for 3D macula, 3D optic disc, radial, and line scans. ICCs for retinal measurements were 0.39, 0.49, 0.71, and 0.69, respectively. Artifacts were present in up to 9% scans. Signal loss because of blinking was the most common artifact on 3D scans (optic disc scan, 7%; macula scan, 9%), whereas segmentation failure occurred in 4% of radial and 3% of line scans. When scans with image artifacts were excluded, ICCs for choroidal thickness increased to 0.95, 0.99, 0.87, and 0.93 for 3D macula, 3D optic disc, radial, and line scans, respectively. ICCs for retinal thickness increased to 0.88, 0.83, 0.89, and 0.76, respectively. CONCLUSIONS Improved repeatability of automated choroidal and retinal thickness measurements was found with the SS OCT after correction of scan artifacts. Recognition of scan artifacts is important for correct interpretation of SS OCT measurements.

PurposeTo evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements.MethodsThe study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes.ResultsMean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements.ConclusionAssessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection.

Purpose To investigate the relationship between macular ganglion cell and inner plexiform layer (mGCIPL) thickness and estimated macular retinal ganglion cell (RGC) counts in glaucoma. Design Observational cohort study. Participants A cross-sectional study of 77 healthy, 154 suspect and 159 glaucomatous eyes from the Diagnostic Innovations in Glaucoma Study (DIGS). Methods All eyes had 24-2 Standard Automated Perimetry (SAP) and optic nerve and macular imaging using high definition optical coherence tomography (HDOCT). The total number of RGCs was estimated using a previously described model that utilizes SAP and OCT circumpapillary retinal nerve fiber layer (cpRNFL) measurements. The number of macular RGCs was estimated from the temporal cpRNFL and SAP test points within the central 10 degrees. Main Outcome Measures The correlation between mGCIPL thickness and estimates of macular RGC counts. Results The average estimated macular RGC count in glaucomatous eyes was 306,010 ± 109,449 cells, which was significantly lower than the estimate of 520,678 ± 106,843 cells in healthy eyes (P < 0.001). Glaucomatous eyes had 41% fewer estimated macular RGCs than healthy eyes and suspects 21% fewer. There was strong correlation between estimated macular RGC counts and mGCIPL thickness (R2 = 0.67; P < 0.001). Macular RGC counts performed better than average mGCIPL thickness in discriminating healthy and glaucomatous eyes with receiver operating characteristic (ROC) curve areas of 0.873 and 0.775, respectively (P = 0.015). Conclusions The strong association between estimated macular RGC counts and mGCIPL thickness and the better diagnostic performance of the macular RGC counts compared to mGCIPL thickness provides further evidence that estimates of RGC number from cpRNFL thickness and SAP sensitivity can be used to assess neural losses in glaucoma.

PurposeTo evaluate choroidal thickness (CT) in healthy and glaucomatous eyes using Swept Source Optical Coherence Tomography (SS-OCT).MethodsA cross-sectional observational study of 216 eyes of 140 subjects with glaucoma and 106 eyes of 67 healthy subjects enrolled in the Diagnostic Innovations in Glaucoma Study. CT was assessed from wide-field (12×9 mm) SS-OCT scans. The association between CT and potential confounding variables including age, gender, axial length, intraocular pressure, central corneal thickness and ocular perfusion pressure was examined using univariable and multivariable regression analyses.ResultsOverall CT was thinner in glaucomatous eyes with a mean (± standard deviation) of 157.7±48.5 µm in glaucoma compared to 179.9±36.1 µm in healthy eyes (P<0.001). The choroid was thinner in both the peripapillary and macular regions in glaucoma compared to controls. Mean peripapillary CT was 154.1±44.1 µm and 134.0±56.9 µm (P<0.001) and macular CT 199.3±46.1 µm and 176.2±57.5 µm (P<0.001) for healthy and glaucomatous eyes respectively. However, older age (P<0.001) and longer axial length (P<0.001) were also associated with thinner choroid and when differences in age and axial length between glaucomatous and healthy subjects were accounted for, glaucoma was not significantly associated with CT. There was also no association between glaucoma severity and CT.ConclusionsGlaucoma was not associated with CT measured using SS-OCT; however, older age and longer axial length were associated with thinner choroid so should be considered when interpreting CT measurements.