María B. Coco-Martín

Precision of higher-order aberration measurements with a new Placido-disk topographer and Hartmann-Shack wavefront sensor

Purpose To assess the intrasession and intersession precision of ocular, corneal, and internal higher‐order aberrations (HOAs) measured using an integrated topographer and Hartmann‐Shack wavefront sensor (Topcon KR‐1W) in refractive surgery candidates. Setting IOBA‐Eye Institute, Valladolid, Spain. Design Evaluation of diagnostic technology. Methods To analyze intrasession repeatability, 1 experienced examiner measured eyes 9 times successively. To study intersession reproducibility, the same clinician obtained measurements from another set of eyes in 2 consecutive sessions 1 week apart. Ocular, corneal, and internal HOAs were obtained. Coma and spherical aberrations, 3rd‐ and 4th‐order aberrations, and total HOAs were calculated for a 6.0 mm pupil diameter. Results For intrasession repeatability (75 eyes), excellent intraclass correlation coefficients (ICCs) were obtained (ICC >0.87), except for internal primary coma (ICC = 0.75) and 3rd‐order (ICC = 0.72) HOAs. Repeatability precision (1.96 × Sw) values ranged from 0.03 μm (corneal primary spherical) to 0.08 μm (ocular primary coma). For intersession reproducibility (50 eyes), ICCs were good (>0.8) for ocular primary spherical, 3rd‐order, and total higher‐order aberrations; reproducibility precision values ranged from 0.06 μm (corneal primary spherical) to 0.21 μm (internal 3rd order), with internal HOAs having the lowest precision (≥0.12 μm). No systematic bias was found between examinations on different days. Conclusions The intrasession repeatability was high; therefore, the devices ability to measure HOAs in a reliable way was excellent. Under intersession reproducibility conditions, dependable corneal primary spherical aberrations were provided. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Design and Evaluation of a Customized Reading Rehabilitation Program for Patients with Age-related Macular Degeneration

PURPOSE To evaluate the efficacy of a reading rehabilitation program (RRP) specifically designed for patients with impaired central vision from age-related macular degeneration (AMD) and the impact of the program on the quality of life (QoL) and to determine any predictable reading performance improvements between visits. DESIGN Prospective case series. PARTICIPANTS Forty-one patients with AMD who attended to the Institute of Applied Ophthalmobiology Eye Institute. METHODS An ad hoc-created RRP comprising 4 customized in-office training and in-home training visits over 6 weeks was undertaken by AMD patients. The RRP was based on the principle of stepwise progressive goal achievement: the difficulty of training tasks increased depending on the success obtained when performing previous easier ones. Reading performance was evaluated during each in-office training visit, and the individuals perception of his or her QoL was assessed before and after the RRP. Reading performance parameters were assessed to evaluate RRP effectiveness. MAIN OUTCOME MEASURES Best-corrected visual acuity (BCVA), reading speed, reading duration, near visual acuity (VA), font size, and the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire scores. The effect sizes (mean differences and standard deviations) also were calculated. RESULTS The mean distance BCVA was 0.81±0.29 logarithm of the minimum angle of resolution units. The mean near VA with the appropriate low-vision aid was 0.91±0.18 (M notation) at baseline. The mean near magnification was 4.32±1.15 at the last in-office visit. The mean reading speed, reading duration, and font size improvement after the reading rehabilitation program were 48.31±22.06 words per minute (P<0.001), 35.46±15.68 minutes (P<0.001), and -4.08±2.19 font points (P<0.001), respectively. The effect sizes of reading speed, reading duration, and font size after the last visit were 2.19, 2.26, and -1.86, respectively. The final score of each WHOQOL-BREF domain improved significantly (P≤0.004) after the RRP. The increased ability to read a smaller font size was correlated with improvement in the physical health domain score of the WHOQOL-BREF (r=0.35; P=0.04). CONCLUSIONS This customized RRP significantly enhanced reading performance and perceived QoL in patients with AMD. The improvement between visits seemed to be consistent. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Precision of a Commercial Hartmann-Shack Aberrometer: Limits of Total Wavefront Laser Vision Correction

PURPOSE To assess the intrasession and intersession precision of higher-order aberrations (HOAs) measured using a commercial Hartmann-Shack wavefront sensor (Zywave; Bausch & Lomb) in refractive surgery candidates. DESIGN Prospective, experimental study of a device. METHODS To analyze intrasession repeatability, 1 experienced examiner measured 30 healthy eyes 5 times successively. To study intersession reproducibility, the same clinician obtained measurements from another 30 eyes in 2 consecutive sessions at the same time of day 1 week apart. RESULTS For intrasession repeatability, excellent intraclass correlation coefficients (ICCs) were obtained for total ocular aberrations, total HOAs, and second-order terms (ICC, > 0.94). The ICCs for third-order terms also were high (ICCs, > 0.87); however, fourth-order ICCs varied from 0.71 to 0.90 (Z(4)(0) = 0.90); and fifth-order ICCs were less than 0.85. For intersession reproducibility, only total ocular aberrations, total ocular HOAs, second-order terms, Z(4)(0), Z(3)(1), and Z(3-)(3) had ICCs of 0.90 or more. Bland-Altman analysis showed that the limits of agreement (were clinically too wide for most higher-order Zernike terms, especially for the third-order terms (> 0.21 μm). CONCLUSIONS Total ocular aberrations, total HOAs, and second-order terms can be measured reliably by Zywave aberrometry without anatomic recognition. Third-order terms and Z(4)(0) are repeatable, but not as reproducible between visits. Fourth-order terms, except for Z(4)(0), and fifth-order terms are not sufficiently reliable for clinical decision making or treatment. Because the variability of Zywave can be a major limitation of a truly successful wavefront-guided excimer laser procedure, surgeons should consider treating HOA magnitudes that are more than the intrasession repeatability values (2.77 × S(w)) as those presented in this study.

Comparison of central corneal thickness using optical low-coherence reflectometry and spectral-domain optical coherence tomography

PURPOSE: To assess intraobserver and interobserver reliability of central corneal thickness (CCT) measurements using optical low‐coherence reflectometry (OLCR) technology and its agreement with spectral‐domain optical coherence tomography (SD‐OCT). SETTING: Rio Hortega University Hospital, Valladolid, Spain. DESIGN: Evaluation of diagnostic technology. METHODS: To analyze OLCR intraobserver repeatability, 1 examiner obtained 4 successive measurements. To study interobserver reproducibility, a different examiner obtained another CCT measurement. To determine agreement with SD‐OCT, the first examiner also obtained CCTs. Intraobserver and interobserver within‐subject standard deviation (Sw), coefficient of variation (CVw), and limits of agreement (LoA) were obtained for OLCR reliability analysis; for study agreement, data were analyzed using the paired‐sample t test and the LoA were calculated. RESULTS: For OLCR intraobserver repeatability, the Sw and precision (1.96×Sw) were 2.33 and 4.56 μm, respectively. The intraobserver CVw was 0.42%. For interobserver reproducibility, the Sw and precision were 11.59 and 22.71 μm, respectively; the CVw was 2.10%. The mean difference between observers was −1.35 μm (95% confidence interval [CI], −3.97 to 1.26). The width of the LoA was 45.27 μm. The mean CCT difference between OLCR and SD‐OCT was 5.68±11.46 μm (95% CI, 8.29‐3.08 μm; P=.0001), and the width of the LoA was 44.93 μm. CONCLUSIONS: Optical low‐coherence reflectometry technology provided reliable intraobserver and interobserver CCT measurements. Although OLCR underestimated the pachymetry by less than 6 μm compared with SD‐OCT, its interchangeability fell within the range of interobserver reproducibility. Both noncontact pachymetry measurements seem to be clinically useful and may be used interchangeably with minimum calibration adjustment. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Early Changes in Corneal Epithelial Thickness after Cataract Surgery - Pilot Study

Abstract Purpose: To assess early variations in central and paracentral corneal epithelial and non-epithelial thicknesses after uneventful clear corneal incision phacoemulsification. Materials and Methods: Twenty patients with a senile cataract underwent coaxial phacoemulsification through a 2.75-mm-wide corneal incision created at 180° in a prospective cohort pilot study. Corneal sublayer thickness measurements were obtained with Fourier-domain optical coherence tomography (FD-OCT, Cirrus HD-OCT, Carl Zeiss Meditec, Inc., Dublin, CA) before and after 1 week and 1 month postoperatively. Central measurements were performed in the middle of the FD-OCT scan and in the 3-mm corneal diameter (paracentral 180° and 0° locations). Epithelial, non-epithelial and total corneal pachymetry were measured at the central and paracentral locations. Results: No significant changes in epithelial thickness were seen 1 week postoperatively. However, 1 month postoperatively, the central, 180°, and 0° paracentral epithelial thicknesses (52.7 ± 3.8, 53.1 ± 5.4, and 52.7 ± 5.3 µm, respectively) decreased significantly (p < 0.01) compared to preoperatively (57.2 ± 4.8, 58.0 ± 5.7, 56.6 ± 5.3 µm, respectively). The 1-week central, 180°, and 0° paracentral non-epithelial corneal thicknesses (515.5 ± 39.6, 534.3 ± 45.6, and 521.3 ± 36.9 µm) were significantly (p < 0.01) higher than preoperatively (486.2 ± 34.7, 498.2 ± 33.8, 497.5 ± 32.3 µm, respectively). The non-epithelial corneal thickness increase was significantly (p = 0.02) greater after 1 week in the central (29.3 ± 17.2 µm) and the 180° paracentral (36.1 ± 28.7 µm) locations than at the 0° paracentral location (23.8 ± 16.5 µm). Conclusions: Immediate postoperative corneal edema following phacoemulsification irregularly affects the cornea at the sublayer level. The initial central and paracentral non-epithelial thickening is compensated by subsequent central and paracentral epithelial thinning. These initial changes occurred more markedly closest to the main incision over the entrance pupil, which may have visual implications.

Dependability of pachymetry measurements after myopic advanced surface ablation using scanning-slit topography and specular microscopy.

PURPOSE To assess the repeatability, intersession and interobserver reproducibility, and agreement of central corneal thickness (CCT) measurements obtained by scanning-slit topography (SST) and noncontact specular microscopy (NCSM) after advanced surface ablation (ASA). METHODS To analyze repeatability, one examiner measured 63 post-myopic ASA eyes five times successively using both techniques randomly. To calculate interobserver reproducibility a second examiner obtained another CCT measurement in a random fashion. To study intersession reproducibility, the first operator obtained CCT measurements from another 24 eyes during two sessions 1 week apart. RESULTS With regard to intrasession repeatability, SST and NCSM within-subject standard deviation (S(w)) and intraclass correlation coefficient (ICC) were 7.35 and 3.81 μm, and 0.97 and 0.99, respectively. For interobserver reproducibility, SST measurement variability showed correlation with CCT magnitude (r(s) = -0.38; P = 0.002), whereas NCSM did not. NCSM S(w) and ICC were 3.83 μm and 0.99, respectively. For intersession reproducibility, no difference in CCT measurements was found for any technique; S(w) and ICC estimates for SST and NCSM were 12.2 and 8.37 μm, and 0.94 and 0.95, respectively. We found a tendency for the difference (mean SST-NCSM = 13.39 μm) to increase in thicker corneas (r(s) = 0.45, P = 0.001). CONCLUSIONS Both noncontact pachymetry techniques provided highly repeatable and quite reproducible CCT measurements in post-ASA patients having no clinically significant corneal haze, except for SST interobserver reproducibility, which decreased in thinner corneas. However, the techniques were not interchangeable. The estimates provided should help clinicians differentiate real CCT change from noncontact pachymetry measurement variability after ASA.

Dependability of posterior-segment spectral domain optical coherence tomography for measuring central corneal thickness.

Purpose: The aim of this study was to assess the intersession and interobserver reliability of central corneal thickness (CCT) measurements using a posterior-segment spectral domain optical coherence tomography (SD-OCT). Methods: Sixty patients were examined with a posterior-segment SD-OCT system (Topcon 3D-OCT). To analyze intersession reproducibility, 1 examiner measured CCT in 60 eyes 2 times 1 week apart, and to study interobserver reproducibility, a second examiner obtained another measurement during the first session. Within-subject reproducibility, coefficient of reproducibility (CR), and intraclass correlation coefficients (ICC) were calculated. Agreement between Topcon 3D OCT and ultrasound pachymetry (USP) was also assessed. Results: Posterior-segment SD-OCT showed an intersession reproducibility of 12.7 &mgr;m (CR = 2.4%) and an excellent ICC (0.96). No systematic difference between sessions was found (average difference, 1.7 &mgr;m; P = 0.15). We found no significant bias between observers (mean difference, −1.5 &mgr;m; P = 0.29). The interobserver reproducibility was 16.4 &mgr;m (CR = 3.1%), and the ICC was 0.94. Topcon 3D OCT CCT values were lower than USP readings (mean difference, 7.6 ± 8.1 &mgr;m; 95% confidence interval, 9.9–5.3 &mgr;m; P < 0.001). Conclusions: With a commercially available retinal SD-OCT system, reliable intersession and interobserver CCT measurements can be feasibly obtained. The criteria for a significant change, which would be the one exceeding the reproducibility, indicate that intersession and interobserver variations in CCT of more than 13 and 16 &mgr;m, respectively, may reflect true corneal change with this particular device. These estimates should help investigators and clinicians differentiate actual CCT modification from measurement random error. The slight CCT underestimation with respect to USP is within the range of other OCT devices.

Clinical utility of combined Placido-scanning-slit midperipheral and thinnest point pachymetry after corneal ablation for myopia.

Purpose: The aim of this study was to assess the random error of the thinnest point and midperipheral pachymetry with a combined Placido–scanning-slit system (Orbscan II) in the intermediate-term follow-up of excimer laser keratorefractive surgery for treating myopia. Methods: Sixty-five patients who had undergone aspheric surface ablation for treating myopia with a minimum follow-up of 6 months, and showed no biomicroscopically detectable corneal haze, were subjected to 5 consecutive topographic examinations. All eyes underwent a complete ophthalmic examination before the surgery. The within-subject SD (Sw), repeatability (2.77 × Sw), coefficient of repeatability (2.77 × Sw/mean), and intraclass correlation coefficients of pachymetry at the thinnest point and in each 4 quadrants at a 6-mm diameter were calculated. Results: The patients had a mean age of 31.9 ± 6.2 years, and the average follow-up was for 7.5 ± 2.6 months. The mean ablation depth for myopia was 63.6 ± 23.6 &mgr;m. The average pachymetry for the thinnest point and midperipheral superior, inferior, nasal, and temporal locations was 456.9, 602.0, 595.5, 609.7, and 566.1 &mgr;m, respectively. The repeatability (and coefficient of repeatability) for the thinnest point and midperipheral superior, inferior, nasal, and temporal locations was 26.5 (5.8%), 37.9 (6.3%), 31.0 (5.2%), 30.5 (5.0%), and 35.4 &mgr;m (6.2%), respectively. The intraclass correlation coefficients were 0.96, 0.88, 0.89, 0.97, and 0.91 for each location, respectively. Conclusions: This study provides the repeatability of the thinnest and midperipheral pachymetry using the combined Placido–scanning-slit system in transparent corneas after laser keratorefractive surgery for treatment of myopia. The test–retest reliability provided here will help differentiate real corneal thickness change from measurement noise. For this, only pachymetric changes >6% are likely to be real and therefore useful when evaluating postoperative keratectasia suspects.

Patient-Reported Outcomes in Spanish Patients Diagnosed with Bilateral Age-Related Macular Degeneration

Purpose: To evaluate the patient-reported outcomes (PRO) in age-related macular degeneration (AMD) patients by using instruments for eliciting health status and vision specific issues. Methods: PRO were assessed using the 25-item National Eye Institute Visual Function Questionnaire (NEIVFQ-25) and the Short-Form General Health Survey (SF-12). Results: The mean age and corrected distance visual acuity (CDVA) in the better eye of the AMD patients were 82.53 ± 5.17 years and 0.82 ± 0.43 logMAR, respectively. The overall NEIVFQ-25 composite score was 57.89. SF-12 physical and mental component summary scores were 37.28 and 57.25, respectively. There were significant correlations (p ≤ 0.05) between CDVA and the following NEIVFQ-25 subscales: general (r = -0.73), near (r = -0.40) and distance vision (r = -0.60), role limitations (r = -0.40), social function (r = -0.48) and mental health (r = -0.38). Conclusions: Visual function is severely affected in AMD patients. It hampers their daily living without, however, deeply disturbing their social function. This may help them retain adequate mental health despite their poor physical status.

Reading Performance Improvements in Patients with Central Vision Loss without Age-Related Macular Degeneration after Undergoing Personalized Rehabilitation Training

ABSTRACT Purpose: To evaluate the efficacy of a reading rehabilitation program (RRP) in patients with central visual loss (CVL) and assess the impact of the RRP on the quality of life (QoL). Methods: The RRP included four in-office and 39 in-home training sessions over 6 weeks. Reading speed, duration, and font size were evaluated during each in-office session. The subjective perception of the QoL was assessed before and after the RRP using the short version of a questionnaire (World Health Organization Quality of Life). A control group who received advice about ocular conditions and low-vision aids also was included. Results: Seventeen patients with Stargardt’s disease (STGD), 11 with adult-onset foveomacular vitelliform dystrophy (AFVD), and eight with myopic macular degeneration (MMD) were included. The control group included five patients each with STGD, AFVD, and MMD. The respective mean corrected distance visual acuities (VAs) in patients with STGD, AFVD, MMD, and the control group were 0.57 ± 0.38, 0.51 ± 0.38, 0.49 ± 0.24, and 0.55 ± 0.25 logarithm of the minimum angle of resolution; the mean corrected near VAs were 0.89 ± 0.20, 1.08 ± 0.17, 0.99 ± 0.34, and 1.18 ± 0.37 (M notation) using low-vision aids. The reading speed, duration, and font size improved in all groups. The RRP groups obtained (p ≤ 0.01) greater improvements than the control group in each reading performance variable assessed. Patients with STGD obtained greater improvements in the subjective evaluation; the control group did not obtain noteworthy improvement in any domain. Conclusions: The RRP improved reading performance in patients with CVL and positively impacted the subjective perception of the QoL.