Bartlomiej J. Kaluzny

Ultra high-speed swept source OCT imaging of the anterior segment of human eye at 200 kHz with adjustable imaging range

We present an application of in vivo anterior segment imaging of the human eye with an ultrahigh speed swept source OCT instrument. For this purpose, a dedicated OCT system was designed and constructed. This instrument enables axial zooming by automatic reconfiguration of spectral sweep range; an enhanced imaging range mode enables imaging of the entire anterior segment while a high axial resolution mode provides detailed morphological information of the chamber angle and the cornea. The speed of 200,000 lines/s enables high sampling density in three-dimensional imaging of the entire cornea in 250 ms promising future applications of OCT for optical corneal topography, pachymetry and elevation maps. The results of a preliminary quantitative corneal analysis based on OCT data free form motion artifacts are presented. Additionally, a volumetric and real time reconstruction of dynamic processes, like pupillary reaction to light stimulus or blink-induced contact lens movements are demonstrated.

Spectral optical coherence tomography: a novel technique for cornea imaging.

Purpose: Spectral optical coherence tomography (SOCT) is a new, noninvasive, noncontact, high-resolution technique that provides cross-sectional images of the objects that weakly absorb and scatter light. SOCT, because of very short acquisition time and high sensitivity, is capable of providing tomograms of substantially better quality than the conventional OCT. The aim of this paper is to show the application of the SOCT to cross-sectional imaging of the cornea and its pathologies. Methods: Eleven eyes with different corneal pathologies were examined with a slit lamp and the use of a prototype SOCT instrument constructed in the Institute of Physics, Nicolaus Copernicus University, Toruń, Poland. Results: Our SOCT system provides high-resolution (4 μm axial, 10 μm transversal) tomograms composed of 3000-5000 A-scans with an acquisition time of 120-200 ms. The quality of the images is adequate for detailed cross-sectional evaluation of various corneal pathologies. Objective assessment of the localization, size, shape, and light-scattering properties of the changed tissue is possible. Corneal and epithelial thickness and the depth and width of lesions can be estimated. Conclusion: SOCT technique allows acquiring clinically valuable cross-sectional optical biopsy of the cornea and its pathologies.

New Directions in Ophthalmic Optical Coherence Tomography

ABSTRACT The rapid development of optical coherence tomography (OCT) and its ophthalmic applications has resulted in the emergence of new laboratory and commercial systems that vary in performance and functionality. The introduction of high-speed imaging capabilities has abrogated the primary limitation of early OCT technology by providing in vivo three-dimensional volumetric reconstructions of both anterior and posterior segments of the human eye within reasonable time constraints. Currently, high-speed swept source OCT technology has made it possible to achieve OCT acquisition speeds of several million A-scans/s. Another direction of OCT development includes the introduction of adaptive optics to imaging of the posterior segment of the eye that allows correction of the eyes static and dynamic aberrations, resulting in the achievement of volumetric cellular resolution retinal imaging. In this review, we introduce readers to various aspects of the development of OCT technology within the context of its ophthalmic applications. We point out directions for future development and indicate different perspectives on this dynamically expanding method. We give a few examples of how OCT has been used over the past few years and describe how high-speed OCT imaging may be used in the future in clinical practice.

Assessment of corneal dynamics with high-speed swept source Optical Coherence Tomography combined with an air puff system

We present a novel method and instrument for in vivo imaging and measurement of the human corneal dynamics during an air puff. The instrument is based on high-speed swept source optical coherence tomography (ssOCT) combined with a custom adapted air puff chamber from a non-contact tonometer, which uses an air stream to deform the cornea in a non-invasive manner. During the short period of time that the deformation takes place, the ssOCT acquires multiple A-scans in time (M-scan) at the center of the air puff, allowing observation of the dynamics of the anterior and posterior corneal surfaces as well as the anterior lens surface. The dynamics of the measurement are driven by the biomechanical properties of the human eye as well as its intraocular pressure. Thus, the analysis of the M-scan may provide useful information about the biomechanical behavior of the anterior segment during the applanation caused by the air puff. An initial set of controlled clinical experiments are shown to comprehend the performance of the instrument and its potential applicability to further understand the eye biomechanics and intraocular pressure measurements. Limitations and possibilities of the new apparatus are discussed.

Corneal topography with high-speed swept source OCT in clinical examination

We present the applicability of high-speed swept source (SS) optical coherence tomography (OCT) for quantitative evaluation of the corneal topography. A high-speed OCT device of 108,000 lines/s permits dense 3D imaging of the anterior segment within a time period of less than one fourth of second, minimizing the influence of motion artifacts on final images and topographic analysis. The swept laser performance was specially adapted to meet imaging depth requirements. For the first time to our knowledge the results of a quantitative corneal analysis based on SS OCT for clinical pathologies such as keratoconus, a cornea with superficial postinfectious scar, and a cornea 5 months after penetrating keratoplasty are presented. Additionally, a comparison with widely used commercial systems, a Placido-based topographer and a Scheimpflug imaging-based topographer, is demonstrated.

Spectral optical coherence tomography: a new imaging technique in contact lens practice

Purpose:  Spectral optical coherence tomography (SOCT) is a new non‐invasive, non‐contact, high‐resolution technique, which provides cross‐sectional images of objects that weakly absorb and scatter light. The aim of this article is to demonstrate the application of SOCT to imaging of eyes fitted with contact lenses.

Spectral optical coherence tomography in video-rate and 3D imaging of contact lens wear.

Purpose. To present the applicability of spectral optical coherence tomography (SOCT) for video-rate and three-dimensional imaging of a contact lens on the eye surface. Methods. The SOCT prototype instrument constructed at Nicolaus Copernicus University (Torun, Poland) is based on Fourier domain detection, which enables high sensitivity (96 dB) and increases the speed of imaging 60 times compared with conventional optical coherence tomography techniques. Consequently, video-rate imaging and three-dimensional reconstructions can be achieved, preserving the high quality of the image. The instrument operates under clinical conditions in the Ophthalmology Department (Collegium Medicum Nicolaus Copernicus University, Bydgoszcz, Poland). A total of three eyes fitted with different contact lenses were examined with the aid of the instrument. Before SOCT measurements, slit lamp examinations were performed. Results. Data, which are representative for each imaging mode, are presented. The instrument provided high-resolution (4 &mgr;m axial × 10 &mgr;m transverse) tomograms with an acquisition time of 40 &mgr;s per A-scan. Video-rate imaging allowed the simultaneous quantitative evaluation of the movement of the contact lens and assessment of the fitting relationship between the lens and the ocular surface. Three-dimensional scanning protocols further improved lens visualization and fit evaluation. Conclusions. SOCT allows video-rate and three-dimensional cross-sectional imaging of the eye fitted with a contact lens. The analysis of both imaging modes suggests the future applicability of this technology to the contact lens field.

Tear meniscus measurement by spectral optical coherence tomography.

Purpose. To evaluate the use of lower tear meniscus measurements obtained with anterior segment Spectral Optical Coherence Tomography (OCT) in quantitative tear evaluation and diagnosis of dry eye syndrome. To verify sensitivity and specificity of different tear meniscus parameters in diagnosis of dry eye syndrome. Methods. A total of 111 eyes in consecutive patients, mean age 34.35 years (SD, 11.17), were enrolled. Each patient completed a standard Ocular Surface Disease Index questionnaire and general ophthalmic examination. Lower tear meniscus was evaluated using Spectral OCT (RTVue, Optovue) with cornea-anterior segment lens short. Three parameters were measured: tear meniscus cross-section area (TMA, mm2), tear meniscus height (TMH, mm), and tear meniscus depth (TMD, mm). Break-up time and Schirmer tests after instillation of topical anesthetic drops were also evaluated. Results. The highest correlation with Schirmer test results was found with TMA, followed by TMH and TMD. Respective Spearman correlation coefficient values were 0.54, 0.52, and 0.3, respectively. TMA, TMH, and TMD measurements were significantly lower in dry eyes than in controls. Sensitivity and specificity for dry eye diagnosis were 80.56% and 89.33% for TMH, 86.11% and 85.33% for TMA, and 77.78% and 52.7% for TMD, respectively. There was a significant negative correlation between both TMA and TMH and Ocular Surface Disease Index questionnaire scores. Conclusions. Lower tear meniscus parameters measured with Spectral OCT correlate well with the Schirmer test, break-up time, and subjective symptoms. TMA and TMH measurements have high sensitivity and specificity for the diagnosis of dry eye syndrome.

Granular corneal dystrophy in 830-nm spectral optical coherence tomography.

Purpose: Spectral optical coherence tomography (SOCT) is a new imaging technique that can provide high-resolution tomograms much faster and with higher sensitivity than conventional Time domain (TdOCT) systems. Its usefulness in producing cross-sectional imaging of different corneal pathologies in vivo has already been presented. The aim of this case report is to show 830-nm SOCT findings in granular corneal dystrophy. Methods: A 48-year-old woman with granular corneal dystrophy was examined with a slit-lamp, confocal microscope (Confoscan 4) and a prototype SOCT instrument constructed at the Institute of Physics, Nicolaus Copernicus University, Torun, Poland. A genetic examination showed a mutation of arginine 555-to-tryptophan (Arg555Trp) in the TGFBI gene that confirmed the clinical diagnosis. Results: SOCT tomograms showed multiple hyperreflective changes throughout the corneal stroma that corresponded to hyaline deposits. Precise and objective assessment of the localization, size, shape, and light scattering properties of the pathologic changes was possible. Three-dimensional rendering of the acquired data allowed a comprehensive evaluation of the deposits in the central cornea. Conclusions: SOCT (830 nm) provides clinically valuable 2- and 3-dimensional assessments of pathomorphologic changes in granular corneal dystrophy in vivo.

Oral acetaminophen (paracetamol) for additional analgesia in phacoemulsification cataract surgery performed using topical anesthesia Randomized double-masked placebo-controlled trial

PURPOSE: To evaluate the clinical analgesic efficacy of 1.0 g oral acetaminophen (paracetamol) given in addition to topical anesthesia before phacoemulsification cataract surgery. SETTING: Inpatient and outpatient ophthalmology clinics, Bydgoszcz, Poland. METHODS: Consecutive patients with age‐related cataract having phacoemulsification under topical anesthesia (tetracaine 0.5%) were enrolled in a prospective double‐blind randomized placebo‐controlled study. Patients were randomly assigned to preoperative oral administration of a placebo medication or to oral administration of 1.0 g acetaminophen. The main outcome measure was intensity of pain during and after surgery. Pain intensity was measured using a 10 cm baseline visual analog scale and a discrete 5‐category verbal rating scale. RESULTS: The study comprised 160 consecutive patients (80 in each group). Intraoperatively, the mean visual analog scale pain intensity score was 2.17 ± 1.81 in the placebo group and 1.45 ± 1.17 in the acetaminophen group and the mean verbal rating scale score, 1.11 ± 0.73 and 0.67 ± 0.66, respectively (P<.01). Postoperatively, the mean visual analog scale score for pain was 1.47 ± 1.39 in the placebo group and 0.56 ± 0.61 in the acetaminophen group and the mean verbal rating scale score, 0.94 ± 0.79 and 0.28 ± 0.41, respectively (P<.01). There was no significant difference in patient behavior during surgery and no significant adverse effects of acetaminophen use. CONCLUSION: Preoperative oral administration of acetaminophen 1.0 g was effective, convenient, safe, and cost effective in reducing intraoperative and postoperative pain in phacoemulsification performed using topical anesthesia. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.