Value of preoperative phakic intraocular lens simulation using optical coherence tomography

PURPOSE: To compare the position of the iris-fixated phakic intraocular lens (pIOL) in preoperative simulation and after implantation using anterior segment optical coherence tomography (AS-OCT). SETTING: Department of Ophthalmology, Academic Hospital Maastricht, Maastricht, The Netherlands. METHODS: In this prospective study, the morphometrics of the anterior chamber were analyzed using preoperative pIOL simulation and postoperative images assessed with AS-OCT. Patients' eyes were examined before and 6 months after pIOL implantation. The measured distances were from the center of the pIOL to the endothelium, from the edge of the pIOL to the endothelium (nasal and temporal side), and from the back of the pIOL to the crystalline lens. RESULTS: Thirty-four eyes (18 patients) were examined. All morphometric parameters showed highly significant correlations and small mean differences between preoperative and postoperative measurements. However, the distance from the nasal edge of the pIOL to the endothelium and the distance from the pIOL to the crystalline lens showed a statistically significant difference between the preoperative simulation and the actual postoperative measurements (P = .045 and P = .001, respectively). The ranges of agreement between all preoperative simulations and postoperative measurements ranged between 0.24 mm and 0.29 mm. CONCLUSIONS: Preoperative simulation was a useful additional tool in the selection of patients considering pIOL implantation and in ensuring the long-term safety of pIOLs. However, clinicians should be aware of the range between the preoperative simulation and the postoperative measurements

Use of Anterior Segment Optical Coherence Tomography to Study Corneal Changes after Collagen Cross-linking

PURPOSE: To investigate the stromal demarcation line after corneal cross-linking using anterior segment optical coherence tomography (AS-OCT) and its influence on the short-term results of cross-linking in patients with progressive keratoconus. DESIGN: Prospective, nonrandomized study. METHODS: Twenty-nine eyes of 29 patients with progressive keratoconus (n = 28) or after laser in situ keratomileusis ectasia (n = 1) were included and treated with corneal cross-linking at our institution. Measurements at 1, 3, 6, and 12 months after corneal cross-linking were: refraction, best-corrected visual acuity (BCVA), tonometry, corneal topography, AS-OCT, specular microscopy, and aberrometry. Demarcation line depth was measured centrally, 2 mm temporally, and 2 mm nasally by two independent observers using AS-OCT and was correlated with clinical parameters. RESULTS: The stromal demarcation line was visible with AS-OCT at 1 month after surgery in 28 of 29 eyes. Pairwise comparisons between the two observers of the AS-OCT measurements did not show a statistically significant difference. After an initial steepening of maximal keratometry values and a decrease in BCVA at 1 month after surgery (both with P < .012), no significant changes were found at 3, 6, and 12 months after surgery compared with before surgery. Refractive cylinder, topographic astigmatism, aberration values, endothelial cell density, and intraocular pressure remained stable during all postoperative visits. A deeper demarcation line depth was associated with a larger decrease in corneal thickness (r = -0.506; P = .012). CONCLUSIONS: AS-OCT is a useful device to detect the stromal demarcation line after corneal cross-linking. At 3 to 12 months follow-up, all clinical parameters remained stable, indicating stabilization of the keratoconic disease

Reproducibility of anterior chamber angle analyses with the swept-source optical coherence tomography in young, healthy Caucasians

PURPOSE: To assess the reproducibility of iridocorneal angle (ICA) analysis in young, healthy Caucasian subjects using swept-source optical coherence tomography (SS-OCT) by determining variability and interobserver agreement between expert and nonexpert observers. METHODS: Thirty-one healthy volunteers (nonexperts) acquired three consecutive SS-OCT images of the right eyes of their peer nonexperts. Images were analyzed by 31 nonexperts and additionally by three experts, whereby the angle opening distance (AOD) and the trabecular iris space area (TISA) at 500 and 750 mum were calculated. A random intercept model was used to determine the amount of variation between observers. In addition, the intra-observer variability between nonexperts and experts was calculated by determining the coefficient of variation (CV). RESULTS: A significant difference was found in the expert analysis for the nasal and temporal angle in the AOD500 (P = 0.002), AOD750 (P < 0.01), and TISA750 (P < 0.01), and the values AOD500 (P = 0.025), AOD750 (P = 0.012), and TISA500 (P = 0.010) were significantly larger if nonexperts analyzed SS-OCT images. The CV was only significant larger for nonexperts for AOD500 (11.1% vs. 8.7%, P < 0.01). CONCLUSIONS: This study demonstrated high reproducibility of angle analysis in young, healthy Caucasian subjects using SS-OCT. Nevertheless, nonexperts obtained significant larger values compared with experts, implying that training is a necessary requirement before analyzing SS-OCT images in ophthalmic practice

Iris-fixated anterior chamber phakic intraocular lens for myopia moves posteriorly with mydriasis.

Item does not contain fulltextPURPOSE: To elucidate the physiological characteristics of eyes implanted with iris-fixated anterior chamber phakic intraocular lenses (pIOLs), which are increasingly being used for the correction of higher myopic and hyperopic refractive errors. METHODS: In a case series of 20 patients (39 eyes), the position of the pIOL to the natural lens and the cornea was evaluated under photopic (135 lux) and low mesopic (< 1 lux) circumstances with anterior segment optical coherence tomography. RESULTS: The distance between the pIOL and the natural lens decreased, and congruently, the distance from the pIOL to the corneal endothelium increased under low mesopic circumstances. CONCLUSIONS: The distance between the pIOL and the corneal endothelium increases when the pupil dilates under dark circumstances, contributing to the already excellent safety data available on pIOL implantation

Case of late-onset corneal decompensation after iris-fixated phakic intraocular lens implantation.

Item does not contain fulltextA 48-year-old myopic patient with bilateral anterior chamber depth of 3.1 mm and endothelial cell density (ECD) of 2525 cells/mm(2) and 2638 cells/mm(2) preoperatively had bilateral implantation of an Artisan iris-fixated phakic intraocular lens (pIOL). Five years postoperatively, unilateral corneal stromal edema was seen in a circumscribed area overlying the temporal ridge of the pIOL in the right eye; the ECD was 1631 cells/mm(2) and the pachymetry, 586 microm. Explantation of the pIOL was refused by the patient. Seven years postoperatively, the ECD was 413 cells/mm(2) in the right eye and corneal decompensation occurred. The progressive unilateral endothelial loss was explained by excessive rubbing of the eyes because of chronic itching and an anterior shift of the pIOL over the 7 years as demonstrated by anterior optical coherence tomography

Influence of anterior chamber morphometrics on endothelial cell changes after phakic intraocular lens implantation

PURPOSE: To analyze the position of iris-fixated phakic intraocular lenses (pIOLs) using anterior segment optical coherence tomography (AS-OCT) and evaluate the effect of anterior chamber morphometrics on endothelial cell changes. SETTING: Department of Ophthalmology, Academic Hospital Maastricht, The Netherlands. METHODS: In this cross-sectional study, AS-OCT was used to measure the distances from the center and the edges of the pIOL to the corneal endothelium in 242 eyes with various models of myopic pIOLs. Endothelial cell measurements were performed preoperatively and at each follow-up examination. RESULTS: The mean follow-up was 34.1 months+/-24.7 (SD) (range 3 months to 7 years). The mean distance between the edge of the pIOL and the endothelium was 1.37+/-0.22 mm. Although this distance was smaller than the safety value of 1.50 mm in 68.6% of the eyes, no eye developed corneal decompensation. There was a significant endothelial cell density (ECD) loss of 1.28%+/-8.46%, 3.25%+/-8.24%, and 5.02%+/-10.40% at 2 years, 5 years, and 7 years, respectively. Linear mixed-model analysis predicted a yearly ECD loss of 0.98% for a mean edge distance of 1.37 mm, 0.15% for an edge distance of 1.59 mm (mean plus 1 SD), and 1.80% for an edge distance of 1.15 mm (mean minus 1 SD). CONCLUSIONS: A shorter distance between the edge of the pIOL and the endothelium was significantly associated with higher ECD loss. For safety reasons, the postoperative examination should include long-term evaluation of the anterior chamber morphometrics in addition to ECD counts

Toric vs Aspherical Control Intraocular Lenses in Patients With Cataract and Corneal Astigmatism: A Randomized Clinical Trial

IMPORTANCE: Spectacle independence is becoming increasingly important in cataract surgery. Not correcting corneal astigmatism at the time of cataract surgery will fail to achieve spectacle independency in 20% to 30% of patients. OBJECTIVE: To compare bilateral aspherical toric with bilateral aspherical control intraocular lens (IOL) implantation in patients with cataract and corneal astigmatism. DESIGN, SETTING, AND PARTICIPANTS: A multicenter, hospital-based, randomized clinical trial was conducted. The participants included 86 individuals with bilateral cataract and bilateral corneal astigmatism of at least 1.25 diopters (D) who were randomized to receive either bilateral toric (n = 41) or bilateral control (n = 45) IOL implantation. INTERVENTIONS: Bilateral implantation of an aspherical toric IOL or an aspherical control IOL. MAIN OUTCOMES AND MEASURES: Spectacle independency for distance vision, uncorrected distance visual acuity, refractive astigmatism, contrast sensitivity, wavefront aberrations, and refractive error-related quality-of-life questionnaire. RESULTS: Preoperatively, mean (SD) corneal astigmatism was 2.02 (0.95) D and 2.00 (0.84) D in the toric and control groups, respectively. Four patients (5%) were lost to follow-up. At 6 months postoperatively, 26 (70%) of the patients in the toric group achieved an uncorrected distance visual acuity of 20/25 or better compared with 14 (31%) in the control group (P < .001; odds ratio, 5.23; 95% CI, 2.03-13.48). Spectacle independency for distance vision was achieved in 31 patients (84%) in the toric group compared with 14 patients (31%) in the control group (P < .001; odds ratio, 11.44; 95% CI, 3.89- 33.63). Mean refractive astigmatism was -0.77 (0.52) D and -1.89 D (1.00) D, respectively. Vector analysis of toric IOLs showed a mean magnitude of error of +0.38 D, indicative of overcorrection. No significant differences were found in contrast sensitivity, higher-order aberrations, or refractive error-related quality of life. CONCLUSIONS AND RELEVANCE: In patients with cataract and corneal astigmatism, bilateral toric IOL implantation results in a higher spectacle independency for distance vision compared with bilateral control IOL implantation. No significant differences were identified in contrast sensitivity, higher-order aberrations, or refractive error-related quality of life following both treatments. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01075542

Detection of Raman spectra in ocular drugs for potential in vivo application of Raman spectroscopy.

Abstract Purpose: Raman spectroscopy holds potential for the assessment of intraocular pharmacokinetics. Raman spectra of ocular drugs were acquired, to determine the drug-specific Raman signature. The ability of the Raman technique to quantify drug concentrations was also investigated. Methods: The experimental setup was based on a High Performance Raman Module 2500 Raman module, designed for 180 degrees "backscatter" signal detection in the wavenumber range of 400-1,800 cm(-1). Excitation source was a diode laser emitting a beam with a wavelength of 785 nm and a power of 10 mW. Laser light was focused in the sample with a long-working-distance microscope objective (25x/0.50). Samples were measured in quartz cuvettes in 10 sequential measurements, with exposure time 30 s. The total number of measured drugs was 49. To determine whether signal intensity and drug concentration correlate, 2 drugs were diluted in water and measured with 120 s exposure time at different concentrations. Results: An active ingredient-specific Raman signature was detected in 4 glaucoma drugs, 6 mydriatics, 5 antibiotics, 4 anesthetics, 3 anti-inflammatory drugs, 2 types of artificial tears, and 5 other drugs. In 20 drugs, no specific Raman signature was detected. Linear correlation of drug concentration with signal intensity was high (R(2)>/=0.94). Conclusions: Using low laser powers, Raman signatures for 29 commonly used ocular drugs were detected. Correlation of drug concentration with signal intensity is high, which is essential for monitoring drug concentration in ocular media. The presented results encourage the use of Raman spectroscopy to acquire detailed information on the pharmacokinetics of these ocular drugs