This PDF file contains the front matter associated with SPIE Proceedings Volume 8930, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

We characterize the relaxation rates of deformations created by focused air puffs with the use of phasestabilized swept source optical coherence elastography (PhS-SSOCE) in tissue-mimicking gelatin phantoms of various concentrations and mouse corneas of different ages in vivo. The results indicate that gelatin of varying concentrations and corneas from different aged mice have different relaxation rates. In addition, the results show that phantoms with higher concentration gelatin and corneas of older mice have higher relaxation rates, which can be attributed to stiffer material. Because this method is non-contact, noninvasive, and utilizes a minimal force which induces a deformation on the scale of μm, this method can be used to study the biomechanical properties of sensitive tissues, such as the cornea.

Animal models of human diseases play an important role in studying and advancing our understanding of these conditions, allowing molecular level studies of pathogenesis as well as testing of new therapies. Recently several non-invasive imaging modalities including Fundus Camera, Scanning Laser Ophthalmoscopy (SLO) and Optical Coherence Tomography (OCT) have been successfully applied to monitor changes in the retinas of the living animals in experiments in which a single animal is followed over a portion of its lifespan. Here we evaluate the capabilities and limitations of these three imaging modalities for visualization of specific structures in the mouse eye. Example images acquired from different types of mice are presented. Future directions of development for these instruments and potential advantages of multi-modal imaging systems are discussed as well.

Pixel clustering algorithm tailored to multi-contrast Jones matrix based optical coherence tomography (MC-JMT) is demonstrated. This algorithm clusters multiple pixels of MC-JMT in a five-dimensional (5-D) feature space which comprises dimensions of lateral space, axial space, logarithmic scattering OCT intensity, squared power of Doppler shift and degree of polarization uniformity. This 5-D clustering provides clusters of pixels, so called as superpixels. The superpixels are utilized as local regions for pixels averaging. The averaging decreases the noise in the measurement as preserving structural details of the sample. A simple decision-tree algorithm is applied to classified superpixels into some tissue types. This classification process successfully segments tissues of a human posterior eye.

Corneal refractive surgery aims to reduce or eliminate refractive errors of the eye by changing the refractive power of the cornea. For the last 20 years controlled excimer laser ablation of corneal tissue, either directly from the corneal stromal surface or from the corneal interior after creation of a superficial corneal flap has become widely used to correct myopia, hyperopia, and astigmatism. Recently, an intrastromal refractive procedure whereby a tissue lenticule is cut free in the corneal stroma by a femtosecond laser and removed through a small peripheral incision has been introduced. This procedure avoids creation of a corneal flap and the potential associated risks while avoiding the slow visual recovery of surface ablation procedures. Precise intrastromal femtosecond laser cutting of the fine lenticule requires very controlled laser energy delivery in order to avoid lenticule irregularities, which would compromise the refractive result and visual acuity. This newly introduced all-femtosecond based flap-free intracorneal refractive procedure has been documented to be a predictable, efficient, and safe procedure for correction of myopia and astigmatism. Technological developments related to further improved cutting quality, hyperopic and individualized treatments are desirable.

Proposed is a novel eye vision system that combines the use of advanced micro-optic and microelectronic technologies that includes programmable micro-optic devices, pico-projectors, Radio Frequency (RF) and optical wireless communication and control links, energy harvesting and storage devices and remote wireless energy transfer capabilities. This portable light weight system can measure eye refractive powers, optimize light conditions for the eye under test, conduct color-blindness tests, and implement eye strain relief and eye muscle exercises via time sequenced imaging. Described is the basic design of the proposed system and its first stage system experimental results for vision spherical lens refractive error correction.

More cost effective and robust designs of ocular adaptive optics systems could probably be derived from a thorough knowledge of ocular time-varying aberrations. This would in particular benefit to therapeutic systems where the problem of robustness is critical. Unfortunately, high frequency temporal statistical behavior of ocular aberrations remains poorly characterized. We set up an original high resolution custom-built Shack-Hartmann aberrometer running at a frequency of 236Hz additionally featuring pupil tracking and performedmeasurements on a 50-eye population. First analyses are carried out over 20 eyes. Qualitative correlation between dynamic aberrations and saccadic pupil movements is highlighted.

A portable pupillometer has been developed which is capable of performing accurate measurements of the pupil diameter during chromatic flicker stimulations. The handheld measuring system records the near-infrared image of the pupil at the rate of 25 fps and simultaneously stimulates the eye using a diffused flicker light generated by light emitting diodes (LEDs). Intensity, frequency and chromatic coordinates of the stimulus can be easily adjusted using a user-friendly graphical interface. Thanks to a chromatic monitoring of the stimulus close to the plane of the eye, photopically matched conditions can be easily achieved. The pupil diameter/area can be measured during flickering stimuli that are generated with frequency in a range of 0.1-20 Hz. The electronic unit, properly connected to the personal computer through a USB port, drives the optical unit, which can be easily held in a hand. The software interface controlling the system was developed in LabVIEW. This paper describes the instrument optical setup, front-end electronics and data processing. Moreover preliminary results obtained on a voluntary are reported.

We report pupillometry results corresponding to three studies. A first study aims at measuring 2D pupil geometry with high precision (below 2 microns) at high frequency (more than 450Hz). The two other studies aim at measuring 3D pupil movements, with and without a chin rest. Results of measurements over 42 subjects are presented.

Evaluation of visual field (VF) is important for clinical diagnosis and patient monitoring. The current VF methods are subjective and require patient cooperation. Here we developed a novel objective perimetry technique based on the pupil response (PR) to multifocal chromatic stimuli in normal subjects and in patients with glaucoma and retinitis pigmentosa (RP). A computerized infrared video pupillometer was used to record PR to short- and long-wavelength stimuli (peak 485 nm and 620 nm, respectively) at light intensities of 15-100 cd-s/m2 at thirteen different points of the VF. The RP study included 30 eyes of 16 patients and 20 eyes of 12 healthy participants. The glaucoma study included 22 eyes of 11 patients and 38 eyes of 19 healthy participants. Significantly reduced PR was observed in RP patients in response to short-wavelength stimuli at 40 cd-s/m² in nearly all perimetric locations (P <0.05). By contrast, RP patients demonstrated nearly normal PR to long-wavelength in majority of perimetric locations. The glaucoma group showed significantly reduced PR to long- and short-wavelength stimuli at high intensity in all perimetric locations (P <0.05). The PR of glaucoma patients was significantly lower than normal in response to short-wavelength stimuli at low intensity mostly in central and 20° locations (p<0.05). This study demonstrates the feasibility of using pupillometer-based chromatic perimetry for objectively assessing VF defects and retinal function and optic nerve damage in patients with retinal dystrophies and glaucoma. Furthermore, this method may be used to distinguish between the damaged cells underlying the VF defect.

Routine clinical measurement of spectral contrast sensitivity is hampered by the time consumption of current methods. We are developing a system that allows instantaneous measurement of spectral contrast sensitivity. The UCST system consists of custom software running on an iPad connected to a calibrated TFT-monitor. Twenty healthy subjects were consecutively randomized to have their spectral contrast sensitivity measured with the UCST strategy or with a Vistech VCTS 6500 chart. The examination time and the spectral contrast sensitivity, respectively, were recorded for each eye in each subject. The Vistech strategy resulted in a more extended mean examination time (CI-Vistech:± (0.95) = 87 ±27 s, d.f. = 9) than the UCST strategy (CI-UCST:μ (0.95) = 13 ±4 s, d.f. = 9), and the estimated mean difference between the two strategies indicated a difference in examination time (CI-difference:μ (0.95) = [47;106] s, d.f. = 18). The overall contrast sensitivity for each group was estimated as the contrast sensitivities for the spatial frequencies sampled, integrated over the spatial frequency band sampled. The Vistech strategy resulted in a higher estimated mean overall contrast sensitivity (CI-Vistech:μ (0.95) = 116±24 log rel.·log [c.·deg^-1], d.f. = 9) than the UCST strategy (CIUCST: μ (0.95) = 74±14 log rel.·log [c.·deg^-1], d.f. = 9), and the estimated mean difference between the two strategies indicated a difference in overall contrast sensitivity (CI-difference:μ (0.95) = [15;68] log rel.·log [c.·deg^-1]), d.f. = 18). It is concluded that the UCST strategy measures spectral contrast sensitivity on the order of 7 times faster than the Vistech strategy. The slightly lower overall contrast sensitivity recorded for the UCST strategy appeared to be due to a limitation in dynamic range that can be overcome with improved design.

The ocular iridocorneal angle is generally an optically inaccessible area when viewed directly through the cornea due to the high angle of incidence required and the large index of refraction difference between air and cornea (n_air = 1.000 and n_cornea = 1.376) resulting in total internal reflection. Gonioscopy allows for viewing of the angle by removing the aircornea interface through the use of a special contact lens on the eye. Gonioscopy is used clinically to visualize the angle directly but only en face. Optical coherence tomography (OCT) has been used to image the angle and deeper structures via an external approach. Typically, this imaging technique is performed by utilizing a conventional anterior segment OCT scanning system. However, instead of imaging the apex of the cornea, either the scanner or the subject is tilted such that the corneoscleral limbus is orthogonal to the optical axis of the scanner requiring multiple volumes to obtain complete circumferential coverage of the ocular angle. We developed a novel gonioscopic OCT (GOCT) system that images the entire ocular angle within a single volume via an “internal” approach through the use of a custom radially symmetric gonioscopic contact lens. We present, to our knowledge, the first complete 360° circumferential volumes of the iridocorneal angle from a direct, internal approach.

The objective of this project was to develop and demonstrate a portable, low-priced, easy to use non-mydriatic retinal camera for eye disease screening in underserved urban and rural locations. Existing portable retinal imagers do not meet the requirements of a low-cost camera with sufficient technical capabilities (field of view, image quality, portability, battery power, and ease-of-use) to be distributed widely to low volume clinics, such as the offices of single primary care physicians serving rural communities or other economically stressed healthcare facilities. Our approach for Smart i-Rx is based primarily on a significant departure from current generations of desktop and hand-held commercial retinal cameras as well as those under development. Our techniques include: 1) Exclusive use of off-the-shelf components; 2) Integration of retinal imaging device into low-cost, high utility camera mount and chin rest; 3) Unique optical and illumination designed for small form factor; and 4) Exploitation of autofocus technology built into present digital SLR recreational cameras; and 5) Integration of a polarization technique to avoid the corneal reflex. In a prospective study, 41 out of 44 diabetics were imaged successfully. No imaging was attempted on three of the subjects due to noticeably small pupils (less than 2mm). The images were of sufficient quality to detect abnormalities related to diabetic retinopathy, such as microaneurysms and exudates. These images were compared with ones taken non-mydriatically with a Canon CR-1 Mark II camera. No cases identified as having DR by expert retinal graders were missed in the Smart i-Rx images.

We describe a method we call "stripe field imaging" that is capable of capturing wide field color fundus videos and images of the human eye at pupil sizes of 2mm. This means that it can be used with a non-dilated pupil even with bright ambient light. We realized a mobile demonstrator to prove the method and we could acquire color fundus videos of subjects successfully. We designed the demonstrator as a low-cost device consisting of mass market components to show that there is no major additional technical outlay to realize the improvements we propose. The technical core idea of our method is breaking the rotational symmetry in the optical design that is given in many conventional fundus cameras. By this measure we could extend the possible field of view (FOV) at a pupil size of 2mm from a circular field with 20° in diameter to a square field with 68° by 18° in size. We acquired a fundus video while the subject was slightly touching and releasing the lid. The resulting video showed changes at vessels in the region of the papilla and a change of the paleness of the papilla.

We demonstrate segmentation of human MGs based on several image processing technic. 3D volumetric data of upper eyelid was acquired from real-time FD-OCT, and its acini area of MGs was segmented. Three dimensional volume informations of meibomian glands should be helpful to diagnose meibomian gland related disease. In order to reveal boundary between tarsal plate and acini, each B-scan images were obtained before averaged three times. Imaging area was 10x10mm and 700x1000x500 voxels. The acquisition time was 60ms for B-scan and 30sec for C-scan. The 3D data was flattened to remove curvature and axial vibration, and resized to reduce computational costs, and filtered to minimize speckles, and segmented. Marker based watershed transform was employed to segment each acini area of meibomian gland.

The gradient refractive-index (GRIN) inside the crystalline lens has been described using a number of functions. One of the most widely used functions for this purpose is the polynomial. Changing the order of the GRIN polynomials alters the relative refractive index profile across (radially) and along (axially) the lens. In this paper, numerical methods are used to investigate the effects of varying GRIN polynomial order on the accommodative response of the lens; in particular, accommodative amplitude. Our results suggest that the GRIN order does not have a significant influence on the accommodation amplitude.

Alterations to the corneal cell metabolism or to the structural organization of collagen fibrils occur in several corneal and systemic pathologies. In this work we resort to multiphoton microscopy corneal imaging to achieve a characterization of the corneal state. Using fluorescence lifetime imaging microscopy (FLIM) the assessment of the metabolic state of corneal cells is possible, whereas second harmonic generation (SHG) imaging can be used to assess corneal structural alterations. A sub-15 fs near-infrared laser source with a broad excitation spectrum was used for SHG imaging and FLIM. The broad spectrum allows simultaneous excitation of both metabolic co-factors. The signals were collected by a photomultiplier tubes (PMT) detector with 16 simultaneous recording channels, which allowed the separation of fluorophores autofluorescence based on their emission wavelengths. We were able to successfully image ex-vivo human and porcine cornea at multiple depths. Simultaneous NADH and flavin autofluorescence, SHG of collagen fibrils, and stroma autofluorescence imaging was performed which may in future allow an improved characterization of the metabolic and structural alterations of the corneal tissue due to pathophysiological conditions. This would be an important step towards a better understanding of corneal dystrophies and systemic metabolic disorders.

Little is known about the structural changes of the ciliary muscle with age and how it may contribute to presbyopia. Optical coherence tomography (OCT) has been used to perform ciliary muscle biometry at different age and accommodative states with low resolution and speed. Dynamic imaging and accurate biometry of the ciliary muscle requires high-speed, high-resolution and correction of the OCT image distortions. We integrate an existing custom-made Spectral Domain OCT (SD-OCT) platform working at 840nm for biometry of the human eye with a SD-OCT system working at 1325nm that enables high-speed and high-resolution transscleral imaging of the ciliary muscle dynamically during accommodation and we developed an algorithm to provide corrected thickness measurements of the ciliary muscle.

We demonstrate the feasibility of our newly developed phase stabilized high-speed (100 kHz A-scans/s) 1 μm sweptsource optical coherence tomography (SSOCT) system with the phase-variance based motion contrast method for visualization of human chorioretinal complex microcirculation. Compared to our previously reported spectral domain (spectrometer based) phase-variance (pv)-SDOCT system it has advantages of higher sensitivity, reduced fringe washout for high blood flow speeds and deeper penetration in choroid. High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. This process does not require additional calibration hardware and complex numerical procedures. Our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. Examples of vasculature in the chorioretinal complex imaged by pv-SSOCT is presented and compared to retinal images of the same volunteers acquired with fluorescein angiography (FA) and indocyanine green angiography (ICGA).

Vision incapacitation and blindness associated with retinal dystrophies affect millions of people worldwide. Retinal degeneration is characterized by photoreceptor cell death and concomitant remodeling of remaining retinal cells. Repetitive Magnetic Stimulation (RMS) is a non-invasive technique that creates alternating magnetic fields by brief electric currents transmitted through an insulated coil. These magnetic field generate action potentials in neurons, and modulate the expression of neurotransmitter receptors, growth factors and transcription factors which mediate plasticity. This technology has been proven effective and safe in various psychiatric disorders. Here we determined the effect of RMS on retinal function in Royal College of Surgeons (RCS) rats, a model for retinal dystrophy. Four week-old RCS and control Spargue Dawley (SD) rats received sham or RMS treatment over the right eye (12 sessions on 4 weeks). RMS treatment at intensity of at 40% of the maximal output of a Rapid2 stimulator significantly increased the electroretinogram (ERG) b-wave responses by up to 6- or 10-fold in the left and right eye respectively, 3-5 weeks following end of treatment. RMS treatment at intensity of 25% of the maximal output did not significant effect b-wave responses following end of treatment with no adverse effect on ERG response or retinal structure of SD rats. Our findings suggest that RMS treatment induces delayed improvement of retinal functions and may induce plasticity in the retinal tissue. Furthermore, this non-invasive treatment may possibly be used in the future as a primary or adjuvant treatment for retinal dystrophy.

Retinal photocoagulation typically results in permanent scarring and scotomata, which limit its applicability to the macula, preclude treatments in the fovea, and restrict the retreatments. Non-damaging approaches to laser therapy have been tested in the past, but the lack of reliable titration and slow treatment paradigms limited their clinical use. We developed and tested a titration algorithm for sub-visible and non-damaging treatments of the retina with pulses sufficiently short to be used with pattern laser scanning. The algorithm based on Arrhenius model of tissue damage optimizes the power and duration for every energy level, relative to the threshold of lesion visibility established during titration (and defined as 100%). Experiments with pigmented rabbits established that lesions in the 50-75% energy range were invisible ophthalmoscopically, but detectable with Fluorescein Angiography and OCT, while at 30% energy there was only very minor damage to the RPE, which recovered within a few days. Patients with Diabetic Macular Edema (DME) and Central Serous Retinopathy (CSR) have been treated over the edematous areas at 30% energy, using 200μm spots with 0.25 diameter spacing. No signs of laser damage have been detected with any imaging modality. In CSR patients, subretinal fluid resolved within 45 days. In DME patients the edema decreased by approximately 150μm over 60 days. After 3-4 months some patients presented with recurrence of edema, and they responded well to retreatment with the same parameters, without any clinically visible damage. This pilot data indicates a possibility of effective and repeatable macular laser therapy below the tissue damage threshold.

The performance of clinical confocal SLO and OCT imagers is limited by ocular aberrations. Adaptive optics (AO) addresses this problem, but most research systems are large, complex, and less well suited to the clinical environment. PSI's recently developed compact retinal imager is designed for rapid, automated generation of cone photoreceptor density maps. The device has a compact foot-print suitable for clinical deployment. The system previously presented at Photonics West and ARVO 2013 has been upgraded to include numerous new features that support clinical research applications. These upgrades significantly enhance the capabilities of the imager, providing the clinician with simultaneously-acquired (registered) en face photoreceptor images and AO-OCT retinal cross-sections.

One of the main problems with glaucoma throughout the world is that there are typically no symptoms in the early stages. Many people who have the disease do not know they have it and by the time one finds out, the disease is usually in an advanced stage. Most retinal cameras available in the market today use sophisticated optics and have several other features/capabilities (wide-angle optics, red-free and angiography filters, etc) that make them expensive for the general practice or for screening purposes. Therefore, it is important to develop instrumentation that is fast, effective and economic, in order to reach the mass public in the general eye-care centers. In this work, we have constructed the hardware and software of a cost-effective and non-mydriatic prototype device that allows fast capturing and plotting of high-resolution quantitative 3D images and videos of the optical disc head and neighboring region (30° of field of view). The main application of this device is for glaucoma screening, although it may also be useful for the diagnosis of other pathologies related to the optic nerve.

In a continuing work of establishing safe limits for UV protection on sunglasses, we have estimated the incident UV radiation for the 280 nm – 400 nm range for 5500 locations in Brazil. Current literature establishes safe limits regarding ultraviolet radiation exposure in the spectral region 180nm–400nm for weighted and unweighted UV radiant exposure. British Standard BSEN1836(2005) and American Standard ANZI Z80.3(2009) require the UV protection in the spectral range 280nm–380nm, and The Brazilian Standard for sunglasses protection, NBR15111(20013), currently requires protection for the 280nm – 400nm range as established by literature. However, none of them take into account the total (unweighted) UVA radiant exposure.Calculations of these limits have been made for 5500 Brazilian locations which included the geographic position of the city; altitude, inclination angle of the Earth; typical atmospheric data (ozone column; water vapor and others) as well as scattering from concrete, grass, sand, water, etc.. Furthermore, regarding UV safety for the ocular media, the resistance to irradiance test required on this standard of irradiating the lenses for 25 continuous hours with a 450W sunlight simulator leads to a correspondence of 26 hours and 10 minutes of continuous exposure to the Sun. Moreover, since the sun irradiance in Brazil is quite large, integrations made for the 280-400 nm range shows an average of 45% of greater ultraviolet radiant exposure than for the 280-380 nm range. Suggestions on the parameters of these tests are made in order to establish safe limits according to the UV irradiance in Brazil.

The transmittance of UVA light through the in vitro human cornea over the thickness of 400um during the corneal collagen cross-linking procedure has been measured using an optical fiber (600 μm core diameter) fixed just before the cornea and attached to Spectrophotometer. The 10 corneas, (average of 6 days post-mortem) were washed with saline and cross-linked with the currently used protocol. To enhance absorption of UV radiation, Riboflavin solution (0.1% and 400 mOsm) was applied prior to and during exposure. The UVA beam - 365nm ± 5nm at 3mW/cm2 ± 0.003mW/cm² - was focused directly onto the corneal stroma. The measured average transmittance of the cornea without Riboflavin was 64.1%. Preceding the irradiation but after 6 applications of Riboflavin at 5min intervals (total of 30min) transmittance decreased to 21.1%. The 30min of irradiation were then accompanied by an additional 6 applications of Riboflavin at 5min intervals (for a total of treatment time of 1h), resulting in a further decrease in transmittance to 12.2%, which is in agreement with current literature. The average transmittance in terms of energy during the 30 minutes irradiation procedure fluctuated from 0.63 to 0.37 mW/cm². These results indicate different levels of UV transmittance during treatment, leading to consider a new personalized treatment with tunable UV power irradiation.

Recent investigations show the need for certificating sunglasses to ensure the safety and health to population. The Brazilian Standard ABNT NBR 15111 regulates features to sunglasses, however, there is not a sunglasses certification office in Brazil, therefore, our lab has been developing several equipment for sunglasses testing. This work refers to one of them: the flammability test system for sunglasses in compliance with the NBR 15111. The standard provides requirements for the flammability test procedure which requires that the equipment must operate at a temperature of 650 °C ± 20 °C; the end of a steel rod of 300 mm length and 6 mm diameter should be heated and pressed over the surface of the lenses for five seconds; the flammability is checked by visual inspection. The furnace is made of ceramic. We used a power electronic circuit to control the power in the furnace using ON/OFF mode and for measuring the temperature, we used a K-type thermocouple. A stepper motor with pulley lifts the steel rod. The system reaches the working temperature in 15 minutes for a step input of 61 V in open loop system. The electronics control are under development in order to shorten the time necessary to reach the working temperature and maintain the temperature variation in the furnace within the limits imposed by the standard as next steps.

Minimally invasive surgery has recently been improved by the use of robot-assisted procedures in several medical fields. Among the ocular surgeries there are a few examples of sophisticated vitreoretinal procedures, while robotic-assisted surgery of the anterior eye segment is still under study. In this paper we propose a new approach to the robotic assisted ocular surgery: a CO2 laser system is equipped with a micromanipulator and scanner, and it is proposed to induce photothermal effects for the removal of neoformations. A sensorized tool is connected to the patient eye and to the robotic arm. This tool is equipped with force and position sensors: by the use of the spatial information from the robotic console and from the patient it is possible to control the position of the target itself and to block it in the correct position for performing surgery. The system is provided by a feedback alarm that remove the block of the patient head in any moment. The optimized robotic consolle can be used in performing scleral cuts and in the treatment of pterigium or neoformations.

Minimally invasive laser assisted surgery in ophthalmology is continuously developing in order to find new surgical approaches, preserve patient tissue and improve surgical results in terms of cut precision, restoration of visual acuity, and invasiveness. In order to achieve these goals, the current approach in corneal transplant is lamellar keratoplasty, where only the anterior or posterior part of the patient’s cornea is substituted depending on the lesion or pathology. In this work, we present a novel alternative approach: a case study of intrastromal sutureless transplant, where a portion of the anterior stroma of a donor cornea was inserted into the stroma of the recipient cornea, aiming to restore the correct thickness of the patient’s cornea. The patient cornea was paracentrally thin, as the result of a trophic ulcer due to ocular pemphigoid. A discoid corneal graft from the anterior stroma of a donor eye was prepared: a femtosecond laser cut with a trapezoidal profile (thickness was 300 μm, minor and major basis were 3.00 and 3.50 mm, respectively). In the recipient eye, an intrastromal cut was also performed with the femtosecond laser using a specifically designed mask; the cut position was 275 μm in depth. The graft was loaded into an injector and inserted as an intrastromal presbyopic implant. The postoperative analysis evidenced a clear and stable graft that selectively restored corneal thickness in the thinned area. Intrastromal corneal transplant surgery is a minimally invasive alternative to anterior or posterior lamellar keratoplasty in select cases. We believe that Sutureless Intrastromal Laser Keratoplasty (SILK) could open up new avenues in the field of corneal transplantation by fully utilizing the potential and precision of existing lasers.

The use of the Hartman-Shack sensor in ophthalmology allowed the identification of higher-order aberrations, which make possible the search for methods to correct them. Customized refractive surgery is one of the most successful methods, although there are patients which cannot be submitted to this surgery due to a variety of abnormal limiting factors such as cornea thickness and quantity of higher-order aberrations. Being this an irreversible process, the alternative is to develop a non-surgical method. This work proposes a method to obtain personalized contact lenses to correct high-order aberrations via the development of a customized ablation system using an excimer laser and a moving piezoelectric mirror. The process to produce such lenses consists of four steps. 1) The map of total aberrations of the patient’s eye is measured by using an aberrometer with a Hartman-Shack sensor. 2) The measured aberration map is used to determine the maps for correction and related distribution of laser pulses for the ablation process with the excimer laser. 3) The lens production is performed following the same principle as customized refractive surgery. 4) The quality control of the lens is evaluated by two tests. 4.1) The lens is measured by a non-commercial lensometer, which is assembled specially for this measurement, as the ones commercially available are not capable of measuring asymmetric and irregular surfaces. 4.2) The evaluation of the lens-eye system is made using the aberrometer of the first step in order to verify the residual aberrations. Here, the lenses are ablated with a customized refractive surgery system.

We present a method for calculating the ideal toric lens to implant in astigmatic patients following cataract surgery. We show that the online calculators provided by major toric IOL manufacturers are insufficient for both theoretical and practical reasons. We reveal important theoretical shortcomings in their approach, illustrated by a number of cases which demonstrate how the approach can lead to errors in lens selection. Our approach combines the spherical and cylindrical power calculations into one, and allows for lens data from any manufacturer to be used, eliminating the reliance on multiple programs.