Normative Pentacam anterior and posterior corneal elevation measurements: effects of age, sex, axial length and white-to-white.

PURPOSE: To provide normal corneal elevation data for a large Caucasian population and to determine the impacts on these data of age, sex, axial length (AXL) and horizontal white-to-white (WW). SETTING: Centro Internacional de Oftalmología Avanzada, Madrid, Spain. DESIGN: Retrospective, cross-sectional, observational. METHODS: In this retrospective, cross-sectional, observational study, anterior and posterior corneal elevations were measured in 789 right eyes of subjects with no ocular disease at the thinnest corneal location in relation to a fixed 8-mm best-fit sphere using the Pentacam, and AXL and WW were measured with the IOLMaster. A multiple linear regression model was used to assess the effects of age, sex, AXL and WW on the elevation data. RESULTS: Mean subject age was 50.5 ± 15 years (range 17-93 years); 64% were women. Mean anterior and posterior corneal elevations were 1.99 ± 1.75 µm (- 7 to 10 µm) and 7.70 ± 5.7 µm (- 6 to 28 µm). Anterior corneal elevations were higher by 0.165 µm and 0.033 µm for every mm reduction in AXL and every year reduction in age, respectively. Sex and WW were not significant predictors of anterior elevations (R2 = 7.7%). Posterior corneal elevation increased by 0.186 µm/year of age, 0.707 µm/mm reduction in WW and 0.819 µm/mm reduction in AXL. This variable was also 0.866 µm greater in men (R2 = 34.4%). CONCLUSION: Anterior corneal elevations decrease with age and are higher for shorter AXL but are not influenced by sex or WW. Posterior corneal elevations increase with age, decreasing AXL, decreasing WW and are higher in men.

Schlemm's canal measured by optical coherence tomography and correlation study in a healthy Caucasian child population.

PURPOSE: To measure the Schlemm's canal (SC) in vivo by Fourier-domain optical coherence tomography (FD-OCT) in a Caucasian paediatric population. METHODS: Participants of this cross-sectional study were 290 healthy children. In the right eye of each child, SC cross-sectional diameter and area measurements were made with the FD-OCT instrument RTVue® (Optovue Inc, Fremont, CA, USA) in the nasal and temporal quadrants. These SC variables were then assessed for correlation with the factors age, gender, refractive error, anterior chamber angle and trabecular meshwork (TM) metrics. Finally, the reproducibility of the SC measurements was assessed in 30 of the participants. RESULTS: Mean participant age was 10.7 ± 3.4 years (range 3-18). SC diameters could be measured in both quadrants in 70.6% and 70.4% of subjects, respectively. Mean SC diameters were similar (p = 0.125) for the temporal and nasal quadrants: 266.7 ± 84.1 µm (range 131-509) and 273.2 ± 77.3 µm (range 124-486), respectively. Mean SC areas were also similar (p = 0.167) for the two quadrants: 9975 ± 3514 µm2 (range 4000-23 000) versus 9688 ± 3297 µm2 (range 3000-24 000). No differences were detected in SC measurements according to gender, refractive error or angle and TM measurements (R ≤ 0.116; p ≥ 0.125). The exception was age which was directly correlated with SC size (p ≤ 0.041). The reproducibility of the SC measurements was excellent (intraclass correlation coefficients ≥0.936). CONCLUSION: FD-OCT allows the identification of the SC in children. Our data indicate an increase in SC size produced with age.

Anterior Chamber Angle Tissue as an Incidental Optical Coherence Tomography Finding in a Large Healthy Caucasian Child Population.

PURPOSE: The aim of this study was to describe the presence of anterior chamber angle (ACA) tissue as an incidental optical coherence tomography (OCT) finding in healthy children. METHODS: For this cross-sectional study, we reviewed Fourier-domain OCT images obtained in 422 children, who were chosen as candidates for inclusion in a prior study, and who visited our clinic for a routine vision test. The presence of angle tissue was assessed in the nasal and temporal quadrants. On tomographies showing angle tissue, several measurements were made, including ACA width and trabecular meshwork length and size. RESULTS: Hyperreflective tissue was observed in the ACA recess in 14 eyes of 13 children subjected to OCT (3.3%). This tissue was only present in 1 quadrant. The mean age of the affected children was 10.1±2.5 years (range, 7 to 14); 69% were female patients. Spherical refractive error was -0.5 to +1.75 D. ACA width was 45.9±9.1 (24.8 to 57.9) in the nasal quadrant and 44.3±10.1 (23.9 to 60.1) in the temporal quadrant. Trabecular meshwork length and size were 494±94 µm (322 to 732) and 0.064±0.018 mm (0.03 to 0.11), respectively. In all 13 children, intraocular pressure was ≤18 mm Hg, the appearance of the optic nerve head was normal, and none had a family history of glaucoma. CONCLUSIONS: We, here, report the incidental observation of angle tissue in a small percentage of healthy Caucasian children. The follow-up of these children in future work could clarify the possible clinical implications of this observation.

Impacts of Implantable Collamer Lens V4c Placement on Angle Measurements Made by Optical Coherence Tomography: Two-Year Follow-up.

PURPOSE: To determine iridocorneal angle changes produced after 2 years of implantable collamer lens (ICL) V4c (STAAR Surgical AG, Nidau, Switzerland) placement by Fourier-domain optical coherence tomography (FD-OCT). DESIGN: Prospective interventional case series. METHODS: In 54 eyes of 27 myopic subjects FD-OCT iridocorneal angle measurements were made before and 1 month, 3 months, 1 year, and 2 years after ICL implant. Trabecular-iris angle (TIA), angle opening distance 500 µm from the scleral spur (AOD500), and iridotrabecular contact length (TICL) were compared among these time points and the nasal, temporal, and inferior quadrants. RESULTS: Preoperative TIAs were 49.5 ± 8.7, 48.3 ± 9.6, and 49.1 ±8.6 degrees for the nasal, temporal and inferior quadrants (P < .001). Corresponding values were 29.9 ± 10.4, 28.4 ± 10.8, and 28.8 ± 9.7 degrees at 1 month and 27.3 ± 8.8, 26.8 ± 8.1, and 28.9 ± 7 degrees at 2 years of follow-up, indicating angle narrowing of 39%-45% and no further narrowing beyond 1 month in the nasal (P = .133), temporal (P = .376), and inferior (P = 1.000) quadrants. Trabecular-iris contact (TIC) was observed in 8 eyes of 8 subjects, mostly only in the temporal quadrant. Mean TICL failed to vary during follow-up (307 ± 288 µm at 3 months and 225 ± 142 µm at 2 years, P = .159). CONCLUSIONS: In response to ICL V4c implant, considerable angle narrowing was detected at 1 month but this narrowing remained stable at 2 years. In the 8 cases of TIC, no progression of contact was observed beyond 3 months postimplant.

Anterior Chamber Angle and Trabecular Meshwork Measurements Made by Fourier-domain Optical Coherence Tomography in Healthy White Children.

PURPOSE: To obtain anterior chamber angle and trabecular meshwork (TM) measurements by Fourier-domain optical coherence tomography (FD-OCT) in a population of healthy white children. MATERIALS AND METHODS: This was a cross-sectional study examining 409 right eyes of 409 children. Trabecular-iris angle (TIA) and TM length and area were measured by FD-OCT (RTVue 100) in the nasal and temporal quadrants to analyze correlations between angle or TM measurements and age, sex, and refractive error. RESULTS: Mean participant age was 10.5±3.4 years (range, 3 to 18 y); 51% were boys. Mean spherical error was 0.56±2.4 D (range, -9 to +7.5 D). TIA could be measured in 99%, whereas TM measurements could only be made in 83%. Mean TIA was 43.1±10.0 degrees (range, 16 to 76 degrees). No differences were observed in angle width according to sex (P=0.299; t test). TIA was correlated with age (R=0.204; P<0.001) and with spherical error (R=-0.457; P<0.001). Mean TM length was 530±106 µm (range, 299 to 891 µm) and mean TM area was 0.065±0.021 mm (range, 0.030 to 0.180 mm). No correlation was observed between TM metrics and age, sex or refractive error (R<0.08; P≥0.172). CONCLUSIONS: FD-OCT proved useful for the noninvasive measurement of TIA and TM metrics in children. Spherical error was the main determinant of TIA.

Quantification of trabecular-iris contact and its prevalence by optical coherence tomography in a healthy Caucasian population.

PURPOSE: To determine the prevalence of trabecular-iris contact (TIC) and quantify this contact in healthy Caucasian individuals using Fourier-domain optical coherence tomography (FD-OCT). METHODS: For this cross-sectional study, 2,012 eyes of 1,006 healthy subjects were recruited among individuals undergoing a routine ophthalmologic checkup. In each participant, age, sex, intraocular pressure, and spherical refractive error were first recorded along with anterior chamber depth and volume, central corneal thickness measured with the Pentacam, and axial length with the IOLMaster. Anterior chamber angle variables and the presence of TIC in the horizontal quadrants were determined by anterior segment FD-OCT (RTVue 100®). When TIC was observed, TIC length (TICL) and its percentage in relation to the length of the trabecular meshwork (TICL percentage) were also measured. RESULTS: Trabecular-iris contact in the horizontal quadrants was observed in 34 eyes of 25 patients, representing 1.6% of the total number of eyes examined. In this subgroup of individuals, mean age was 55.8 years, 84% were women, and spherical refractive error ranged from -0.25 to 8.25 D. Eyes with TIC showed an angle width of less than 23.2 degrees and axial length shorter than 23.7 mm. Mean TICL was 239 ± 79 µm (103-495 µm) and mean TICL percentage was 46.9% ± 13.9% (17.2%-76.3%). CONCLUSIONS: The prevalence of TIC was low in this population. Fourier-domain optical coherence tomography emerged as useful to assess its prevalence and quantify the extent of TIC.

Effects of Implantable Collamer Lens V4c Placement on Iridocorneal Angle Measurements by Fourier-Domain Optical Coherence Tomography.

PURPOSE: To assess by Fourier-domain optical coherence tomography (FDOCT) changes produced in iridocorneal angle measurements in patients undergoing Visian Implantable Collamer Lens (ICL) V4c (STAAR Surgical AG) placement. DESIGN: Prospective interventional case series. METHODS: In 50 eyes of 25 myopic subjects consecutively scheduled for ICL implant, FDOCT (RTVue; Optovue Inc) iridocorneal angle measurements were made before and 1 and 3 months after surgery. Trabecular-iris angle (TIA) and angle opening distance 500 µm anterior to the scleral spur (AOD500) were compared among the quadrants nasal, temporal, and inferior, and correlations with ocular variables including lens vault were examined. RESULTS: Preoperative TIA was 48.7 ± 8.7, 48.2 ± 8.7, and 48.7 ± 9.3 degrees for the nasal, temporal, and inferior quadrants, with no differences (P = 1.000). Following ICL implant, corresponding values fell to 31.2 ± 11.5, 30.0 ± 10.7, and 29.7 ± 8.1 degrees at 1 month postsurgery, indicating angle narrowing of 34%-42%, and to 30.6 ± 12.3, 30.1 ± 11.9, and 29.8 ± 12.3 degrees, respectively, at 3 months postsurgery. Angle measurements failed to vary between 1 month and 3 months postsurgery (P = .481). In 8 eyes, iridotrabecular contact attributable to surgery was observed. One month after surgery, vault measurements correlated with TIA (R = -.309; P = .048). Six variables were identified as predictors of TIA at 1 month postsurgery (R(2) = .907). CONCLUSIONS: Although considerable angle narrowing was detected 1 month after ICL V4c implant, this narrowing remained stable at 3 months postsurgery. Factors predictive of TIA could serve to identify suitable candidates for ICL placement.