Corneal Lens Research Articles

Syndrome D’aniridie Associé À La Dermatite Atopique: À Propos D’un Cas

Aniridia syndrome is a genetic anomaly affecting all ocular structures; it is transmitted by an autosomal dominant mode. In its isolated form aniridia is characterized by a hypoplasia of the iris frequently associated with other ocular anomalies. It the syndromic form it is associated to other systemic abnormalities. Authors are here reporting a case of aniridia associating: a corneal pannus, total aniridia, lens ectopia, and cataract found in a 14 years old girl. She also presented an atopic background with a positive family history of atopia. She is issued from a first degree consanguineous marriage. The management was multidisciplinary. In ophthalmology she underwent an intra-capsular extraction of the lens in both eyes with no intra-ocular lens implantation. Dermatological management was treatment of cuteanous lesions with emollients, corticoids and antihistamines drugs and ointments.

In-vitro method for determining corneal tissue friction and damage due to contact lens sliding

It is postulated that frictional energy due to contact lens rubbing against corneal tissue correlates positively with cell damage; where the damage is due to a fatigue mechanism (repeated stressing). Efforts were made to develop a relatively rapid in-vitro method capable of exploring this postulate. Measurements of the dynamic coefficient of friction (DCoF) between corneal epithelium and contact lenses, associated frictional forces, frictional energy, and corresponding cell damage were made using SkinEthic (Lyon, France) human corneal epithelial (HCE) constructs and commercially available contact lenses. Five silicone hydrogels (SiHs) and two polyhydroxyethlymethacrylate (p-HEMA) lens types were employed. Frictional forces were measured while the lens was rubbed against a construct that was moistened using a tear-like fluid. The exposed constructs were stained, imaged, and processed using a custom Matlab code. The range of DCoF values observed here extended from about 0.04 to 0.07. The frictional energy varied from about 0.03mJ to 0.08mJ. The results indicated a moderate correlation (Pearson's R=0.79, P=3.4%) between the frictional energy and cell damage. The authors believe that these results support the notion that cell damage can be caused by fatigue. Future efforts should explore how cell damage relates to a potentially more relevant metric, power density.

Repeatability and agreement in optical biometry of a new swept-source optical coherence tomography–based biometer versus partial coherence interferometry and optical low-coherence reflectometry

To estimate the repeatability of biometric parameters obtained with a new swept-source biometer and to compare the agreement with that of partial coherence interferometry (PCI) and optical low-coherence reflectometry (OLCR). Department of Ophthalmology, Helios Hospital Erfurt, Erfurt, Julius-Maximilians University, Würzburg, and Philipps University, Marburg, Germany. Prospective comparative multicenter clinical study. Biometry was taken with the use of 3 different biometers: the IOLMaster 700 swept-source biometer, the PCI-based IOLMaster 500, and the OCLR-based Lenstar LS 900. Axial length (AL), anterior chamber depth (ACD), and spherical equivalent (SE) were compared between swept-source and PCI biometry and central corneal thickness (CCT) and lens thickness (LT) between swept-source and OLCR biometry. The repeatability of swept-source biometry was evaluated on the basis of 3 measurements captured for each patient. One hundred twenty cataract eyes were included in the study. The mean difference between swept-source and PCI biometry for AL, ACD, and SE measurements was 4 μm ± 25 (SD), 17 ± 122 μm, and -0.001 ± 0.19 diopter (D), respectively. The mean difference between swept-source and OLCR biometry for LT and CCT measurements was 21 ± 122 μm and 0.15 ± 4.51 μm, respectively. Differences between swept-source biometry and the other devices distributed around zero without statistical significance. The standard deviation of repeatability for AL, ACD, LT, CCT, and SE was 8.8 μm, 9.8 μm, 2.3 μm, 19.5 μm, and 0.1 D, respectively. Swept-source biometry showed high repeatability performance for all biometric parameters. The agreement of AL, ACD, and SE between swept-source and PCI biometry as well as that of LT and CCT between swept-source and OLCR biometry was excellent. It remains to be validated whether high repeatability shown by swept-source biometry will result in better postoperative refractive outcomes. Drs. Blum and Sekundo are members of the Scientific Advisory Board of Carl Zeiss Meditec AG. Drs. Peter and Bühren are employees of Carl Zeiss Meditec AG.

Cataract prevalence, etiology, and systemic association in children attending EI walidain Charity Eye Hospital from April to July 2015

Background: Childhood cataracts are responsible for 5%–20% of blindness in children worldwide and for an even higher percentage of childhood visual impairment in developing countries. This study is an attempt to evaluate the prevalence, etiology, and systemic association of cataract in Sudanese children attending El walidain Charity Eye Hospital. Materials and Methods: this is a cross-sectional, observational prospective study in the period between April and July 2015. Out of 783 children were enrolled in this study, 52 children aged ≤18 years presented with cataract to El walidain Charity Eye Hospital in Khartoum state in the period between April and July 2015. Diagnosis of cataract was made based on history and clinical examination using ophthalmoscope and slit lamp. Results: Prevalence was 6.6%. Nearly 63% of the patients were male, mostly were male, usually idiopathic and juvenile in nature, corneal opacity and photophobia in addition to lens opacity manifested were the usual presentation. Trauma, steroid therapy, congenital, Down syndrome, and other systemic diseases found to be a risk factor. Conclusion: The prevalence of cataract in children in El walidain Charity Eye Hospital was more than that of a hospital-based study done in Tanzania. The mean age of patients was 6.1 years. Corneal opacity and lens opacity were the most common symptoms and signs, respectively. Idiopathic cataract was the most common type and decreased vision was the most common complication.

Coloured cornea replacements with anti-infective properties: expanding the safe use of silver nanoparticles in regenerative medicine.

Despite the broad anti-microbial and anti-inflammatory properties of silver nanoparticles (AgNPs), their use in bioengineered corneal replacements or bandage contact lenses has been hindered due to their intense yellow coloration. In this communication, we report the development of a new strategy to pre-stabilize and incorporate AgNPs with different colours into collagen matrices for fabrication of corneal implants and lenses, and assessed their in vitro and in vivo activity.

Riboflavin for corneal cross-linking.

Corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A (UVA) radiation is the first therapeutic modality that appears to arrest the progression of keratoconus and other corneal ectasias. Riboflavin is central to the process, acting as a photosensitizer for the production of oxygen singlets and riboflavin triplets. These free radicals drive the CXL process within the proteins of the corneal stroma, altering its biomechanical properties. Riboflavin also absorbs the majority of the UVA radiation, which is potentially cytotoxic and mutagenic, within the anterior stroma, preventing damage to internal ocular structures, such as the corneal endothelium, lens and retina. Clinical studies report cessation of ectatic progression in over 90% of cases and the majority document significant improvements in visual, keratometric and topographic parameters. Clinical follow-up is limited to 5-10 years, but suggests sustained stability and enhancement in corneal shape. Sight-threatening complications are rare. The optimal stromal riboflavin dosage for CXL is as yet undetermined.

OCT-based crystalline lens topography in accommodating eyes.

Custom Spectral Domain Optical Coherence Tomography (SD-OCT) provided with automatic quantification and distortion correction algorithms was used to measure anterior and posterior crystalline lens surface elevation in accommodating eyes and to evaluate relationships between anterior segment surfaces. Nine young eyes were measured at different accommodative demands. Anterior and posterior lens radii of curvature decreased at a rate of 0.78 ± 0.18 and 0.13 ± 0.07 mm/D, anterior chamber depth decreased at 0.04 ± 0.01 mm/D and lens thickness increased at 0.04 ± 0.01 mm/D with accommodation. Three-dimensional surface elevations were estimated by subtracting best fitting spheres. In the relaxed state, the spherical term accounted for most of the surface irregularity in the anterior lens (47%) and astigmatism (70%) in the posterior lens. However, in accommodated lenses astigmatism was the predominant surface irregularity (90%) in the anterior lens. The RMS of high-order irregularities of the posterior lens surface was statistically significantly higher than that of the anterior lens surface (x2.02, p<0.0001). There was significant negative correlation in vertical coma (Z3 (-1)) and oblique trefoil (Z3 (-3)) between lens surfaces. The astigmatic angle showed high degree of alignment between corneal surfaces, moderate between corneal and anterior lens surface (~27 deg), but differed by ~80 deg between the anterior and posterior lens surfaces (including relative anterior/posterior lens astigmatic angle shifts (10-20 deg).

Anterior chamber and refractive parameters in diabetic patients according to metabolic status

PurposeDiabetes Mellitus is associated with changes in refractive parameters. Some aspects already studied were the corneal biomechanics and lens thickness. Although, the discussion about anterior chamber angle and depth is still open.The author objective was to analyze and correlate the anterior chamber depth, lens vault and lens thickness with disease duration and metabolic status.MethodsProspective case‐control study. The anterior chamber and refractive parameters were studied using the Visante OCT and the differences between diabetic patients with metabolic control and disease stability were determined (group 1), without (group 2) and group‐control (3). The metabolic control is based on HbA1c levels. The cut‐off considered was 7%.ResultsA total of 64 patients were evaluated (group 1 – n = 21; group 2 – n = 20; group 3 – n = 23). The mean age was 64.32 ± 7.55 years and approximately 5 years of disease duration. In both groups of diabetic patients we found thicker lens, narrow anterior chamber and higher lens vault compared to control group. There was a difference between diabetic groups exists, but it was not statistically significant.ConclusionsThe anterior chamber angle and lens vault are influenced by the serum glucose levels. Further studies will be necessary to clarify the physiopathology mechanism responsible for the anterior segment modifications.

Anterior chamber and refractive parameters in diabetic patients according to metabolic status

PurposeDiabetes Mellitus is associated with changes in refractive parameters. Some aspects already studied were the corneal biomechanics and lens thickness. Although, the discussion about anterior chamber angle and depth is still open.The author objective was to analyze and correlate the anterior chamber depth, lens vault and lens thickness with disease duration and metabolic status.MethodsProspective case–control study. The anterior chamber and refractive parameters were studied using the Visante OCT and the differences between diabetic patients with metabolic control and disease stability were determined (group 1), without (group 2) and group‐control (3). The metabolic control is based on HbA1c levels. The cut‐off considered was 7%.ResultsA total of 64 patients were evaluated (group 1 – n = 21; group 2 – n = 20; group 3 – n = 23). The mean age was 64.32 ± 7.55 years and approximately 5 years of disease duration. In both groups of diabetic patients we found thicker lens, narrow anterior chamber and higher lens vault compared to control group. There was a difference between diabetic groups exists, but it was not statistically significant.ConclusionsThe anterior chamber angle and lens vault are influenced by the serum glucose levels. Further studies will be necessary to clarify the physiopathology mechanism responsible for the anterior segment modifications.

Improving vision and comfort of patients with corneal deformations with implementation of ultraHealth and ultraHealth FC S‐H Hybrid Lenses

SummaryIn spite of the quadrant specific lens designs, fitting GP lenses to protruded corneas is a greater fitting compromise compared with fitting regular shaped corneas with GP corneal lenses. Also as GP corneal lenses have direct mechanical impact on unhealthy, more vulnerable KC epithelium, they are more likely to induce erosions, abrasions and other mechanical changes. Additionally, due to lack of centration evoked by misalignment of the tip of the cone and optical axis of the cornea, the visual outcome of GP corneal lens wear in patients with corneal irregularity in comparison to GP wear in regular shape corneas patients is usually worse. Synergeyes UltraHealth and UltraHealth Flat Curve hybrid lenses are designed to reduce or eliminate interaction between the part of the cornea within the area of the protrusion, and the back surface of the lens. In addition, size of Synergeyes hybrid lenses is 14.5 mm what usually results in better centration over the visual axis which leads to a reduction of HOA; thus they give a better visual quality outcome. Hypoxia, one of major drawbacks of former hybrid lenses, is greatly alleviated with the new materials that are available. Therefore, currently it is possible to diminish or in some cases entirely exclude complications enhancing the visual outcome at the same time.

Quantitative characterization of adhesion and stiffness of corneal lens of Drosophila melanogaster using atomic force microscopy

Atomic force Microscopy (AFM) has become a versatile tool in biology due to its advantage of high-resolution imaging of biological samples close to their native condition. Apart from imaging, AFM can also measure the local mechanical properties of the surfaces. In this study, we explore the possibility of using AFM to quantify the rough eye phenotype of Drosophila melanogaster through mechanical properties. We have measured adhesion force, stiffness and elastic modulus of the corneal lens using AFM. Various parameters affecting these measurements like cantilever stiffness and tip geometry are systematically studied and the measurement procedures are standardized. Results show that the mean adhesion force of the ommatidial surface varies from 36nN to 16nN based on the location. The mean stiffness is 483±5N/m, and the elastic modulus is 3.4±0.05GPa (95% confidence level) at the center of ommatidia. These properties are found to be different in corneal lens of eye expressing human mutant tau gene (mutant). The adhesion force, stiffness and elastic modulus are decreased in the mutant. We conclude that the measurement of surface and mechanical properties of D. melanogaster using AFM can be used for quantitative evaluation of ‘rough eye’ surface.

Hydrogel Ring for Topical Drug Delivery to the Ocular Posterior Segment

Purpose: To investigate the efficacy of a topical hydrogel ring for drug delivery to the posterior segment of the rabbit eye.Materials and methods: Novel hydrogel corneal lenses (CL), scleral/corneal lenses (S/CL), and rings were prepared using poly(hydroxyethyl methacrylate). The devices were immersed in 0.3% ofloxacin ophthalmic solution (OOS) to homogeneously distribute the drug throughout the hydrogel. The medicated CL, S/CL, Ring 1 (standard ring), or Ring 2 (shape-optimized ring) was applied to the surface of the cornea, cornea/bulbar conjunctiva, or bulbar conjunctiva of albino rabbits, respectively. Medicated rings did not touch the corneal surface. In another group, one OOS drop was administered to the eye. After 0.25–8 hours, the hydrogel devices were removed and ocular tissues were harvested. High-performance liquid chromatography (HPLC) was used to measure the ofloxacin concentration in the devices and tissues. The drug concentrations in the posterior segment tissues were compared among ofloxacin delivery methods.Results: One hour after placement, eyes treated with Ring 1 or S/CL had markedly higher ofloxacin levels in the posterior segment tissues (conjunctiva, sclera, and retina/choroid) than eyes treated with topical OOS or a CL. Lower levels of ofloxacin were found in anterior segment tissues (cornea and aqueous humor) in eyes treated with Ring 1 compared to those treated with S/CL. Ring 2 most effectively delivered ofloxacin to the retina/choroid. The tissue ofloxacin concentration in the fellow eye was markedly lower than the eye treated with Ring 2.Conclusions: Our results suggest that hydrogel rings are effective in delivering topical ophthalmic drugs to the posterior segment. The drugs are most likely delivered via the transconjunctival/scleral route by lateral diffusion across the bulbar conjunctiva and through the sclera. Systemic drug delivery to the posterior segment is minimal.

Correlation of Serial Scleral and Corneal Pneumatonometry

To evaluate the usefulness of scleral pneumatonometry as an alternative for corneal measurements of intraocular pressure (IOP) over a broad range of IOPs. Prospective, observational cohort study. The study was conducted in the University of California, San Francisco, Retina Clinic between August and November 2013 in 33 adult patients (age range, 34-94 years; mean ± standard deviation, 74.1±13.4 years) receiving anti-vascular endothelial growth factor intravitreal injections, which transiently increase IOP. Corneal pachymetry and serial corneal and temporal scleral pneumatonometry (baseline, immediately after, and 10, 20, and 30 minutes after injection) were collected. One-time baseline corneal and scleral pneumatonometry readings were obtained in the noninjected eye. Correlation analysis and a Bland-Altman plot were used to evaluate reliability and agreement between scleral and corneal measurements of IOP. A linear mixed model was used to determine the relationship between measurements and to perform covariate analyses. Scleral and corneal pneumatonometry showed nearly 1:1 linear correlation, although scleral pneumatonometry was biased toward higher values (r= 0.94; P < 0.001). Scleral pneumatonometry averaged 9.0 mmHg higher than corneal pneumatonometry (95% limits of agreement,-1.5 to 19.5 mmHg). A linear mixed model resulted in the following equation: corneal IOP= 1.04× scleral IOP- 10.37. Age, central corneal thickness, laterality, and glaucoma and lens status did not impact this relationship. The difference between corneal and scleral pneumotonometry was correlated between the two eyes of individual patients (r= 0.75; P < 0.001). Differences between serial scleral measurements reflect differences between serial corneal measurements. Scleral pneumatonometry should be considered as an alternative to corneal pneumatonometry for following patients in whom corneal measurements are unreliable or unobtainable.

Clinical comparison between brachytherapy of 0.5% loteprednol etabonate eye drops and long-term therapy of 0.1% fluorometholone eye drops after LASEK

Background Conventional corticosteroid therapy after laser epithelial keratomileusis (LASEK) is topical application of 0.1% fluorometholone eye drops for 4 months, but this therapy increases the ocular hypertension risk and leads to poor compliance in patients. It is necessary to explore a safe and effective brachytherapeutic drug. Objective This study was to compare the clinical outcomes between the brachytherapy of 0.5% loteprednol etabonate eye drops and the long-term therapy of 0.1% fluorometholone eye drops after LASEK. Methods Clinical data were retrospectively analyzed from 208 right eyes in 208 mild and moderate myopia patients who received LASEK at Peking University Third Hospital from 2009 to 2013. The eye drops of 0.5% loteprednol etabonate was used 6 times daily since operation day until postoperative day 5, and 4 times daily for a week, and then tapered for three consecutive weeks in 104 eyes of the loteprednol group after LASEK, and 0.1% fluorometholone eye drops was applied topically 4 times daily for initial one month and then tapered for three consecutive months in another 104 eyes in the fluorometholone group after LASEK. Corneal epithelial healing time was compared between the two groups by recording the wearing duration of corneal contact lens. Noncontact intraocular pressure (IOP) was detected and corrected 5 days, 2 weeks, 1 month and 3, 6 months after LASEK. Haze was scored based on the criteria of Cheng under the slit lamp microscope and apparently optometry was performed 1 month and 3, 6 months after LASEK. Results The number of eyes removed corneal contact lens in 5, 6 and 7 days after LASEK was not significantly different between the loteprednol group and the fluorometholone group (χ2=1.180, P=0.554). No considerable differences were seen in the eye numbers with the equivalent spherical lens (absolute value) ≤0.5 D in 1 month, 3 months and 6 months after LASEK (Z=-1.028, P=0.304; Z=-0.398, P=0.691; Z=-0.445, P=0.656). In the fifth days after surgery, the median corrected IOP was 13.52 mmHg and 13.12 mmHg in the loteprednol group and the fluorometholone group, respectively, showing a significant difference between them (Z=-1.985, P=0.047), but no significant differences were found in IOP in 2 weeks, 1 month and 3 months, 6 months after surgery between the two groups (all at P>0.05). IOP elevated (postoperative IOP-preoperative IOP≥5 mmHg) after LASEK in 5 eyes in the loteprednol group and 4 eyes in the fluorometholone group (χ2=0.116, P=0.733). In 1 month after surgery, the number of eyes in different grades of haze was significantly decreased in the loteprednol group compared with the fluorometholone group (χ2=13.506, P=0.009), however, there was no significant differences in haze grading in postoperative 3 months and 6 months between the two groups (χ2=2.199, P=0.699; χ2=1.154, P=0.562). Conclusions Brachytherapy of 0.5% loteprednol etabonate eye drops appears to have a similar effect in anti-inflammation and inhibition of haze to the long-term therapy of 0.1% fluorometholone eye drops after LASEK. Furthermore, topical application of 0.5% loteprednol etabonate eye drops dose not increase the risk of ocular hypertension. Key words: Adrenal cortex hormones/therapeutic use; Anti-inflammatory agents/therapeutic use; Keratomileusis, laser epithelial; Myopia/surgery; Postoperative complications/drug therapy; Loteprednol etabonate; Fluorometholone; Eye drops; Comparative study

Anterior ocular abnormalities of captive Asian elephants (Elephas maximus indicus) in Thailand.

To survey and classify anterior ocular abnormalities in 1478 captive Asian elephants (Elephas maximus indicus) in six regions of Thailand. Anterior ocular examination was performed in both eyes (n=2956) of 1478 elephants selected from the annual health check program involving 2958 animals within six regions of Thailand from January to November 2013. Lesions were described and compared between age and gender. A total of 17.83% (527/2956) of examined eyes from 24.97% (369/1478) of examined elephants had anterior ocular abnormalities. The most common lesions in these examined eyes were frothy ocular discharge (5.85%), corneal edema (5.31%), and conjunctivitis (5.18%). In addition, epiphora, phthisis bulbi, other corneal abnormalities, anterior uveitis, and lens abnormalities were noted. Almost all lesions increased in frequency with age (P<0.01). Regular ophthalmic examination in elephants should be included in their annual health check program. Early detection and treatment of any ocular abnormality may avoid the development of subsequent irreversible ocular pathology.

Intraocular lens power calculation following laser refractive surgery.

Refractive outcomes following cataract surgery in patients that have previously undergone laser refractive surgery have traditionally been underwhelming. This is related to several key issues including the preoperative assessment (keratometry) and intraocular lens power calculations. Peer-reviewed literature is overwhelmed by the influx of methodology to manipulate the corneal or intraocular lens (IOL) powers following refractive surgery. This would suggest that the optimal derivative formula has yet been introduced. This review discusses the problems facing surgeons approaching IOL calculations in these post-refractive laser patients, the existing formulae and programs to address these concerns. Prior published outcomes will be reviewed.

Fine Structure of the Compound Eyes of Callitettix versicolor (Insecta: Hemiptera)

ABSTRACT The external morphology and internal anatomy of the compound eyes of the adults of the rice spittlebug Callitettix versicolor (F., 1794) (Insecta: Hemiptera: Cercopidae) are described for the first time with light, scanning, and transmission electron microscopy observations. The eyes of C. versicolor are of the apposition type and each eye consists of ∼2,042 ommatidia. Each ommatidium is composed of a plano-convex corneal lens, a eucone-type crystalline cone, eight retinular cells, two primary pigment cells, and an undetermined number of secondary pigment cells (probably six). The rhabdomeres of the eight retinular cells form a centrally fused rhabdom surrounded by palisades. The distal end of the rhabdom is funnel shaped around the proximal region of the crystalline cone. The microvilli of the rhabdom are arranged in orthogonal directions suggesting polarization sensitivity. With a small F-number of 1.48 and a large interommatidial angle Δφ of 7.7°, the eye possesses high light sensitivity but l...

Corneal health and contact lens wear: Ion chromatography as an electrolyte probe

Purpose: Tear osmolarity and the concentrations of ocular electrolytes in the eye are known to influence corneal health. Similarly, corneal cells are known to be sensitive to changes in electrolyte balance. Ion transport through contact lenses can influence electrolyte equilibration between preand post-lens tear film. Until now no suitable technique has been identified to quantify these effects. This study utilised ion chromatography to examine multiple ion transport through lenses and the measurement of ex-vivo tear samples. Methods:AmodifiedDionex ion chromatographenabled simultaneous measurement of Na+/K+/Ca2+ and Mg2+ concentrations in both single (5 l) tear samples and lens/membrane permeation studies. In addition to commercial contact lenses, conventional HEMA membranes (40% water) and acrylamide-based corneal model hydrogel membranes (ca 90% water) were mounted in purpose-designed permeability cells and the transport of mixed electrolytes (e.g. 0.25M NaCl, KCl and CaCl2) measured. Results: In baseline studies, the relative ratio of the main tear cations measured in healthy tear film samples was found to be Na+:K+:Ca2+:Mg2+ =140:11:1.2:1. This accord with the observation that the range of K+ concentrations in tears (ca 15–30mM) is high and Ca2+ and Mg2+ concentrations (ca 0.4–0.8 and 0.5–1.1mM) is low, relative to serum. The relative permeability coefficients of lenses and membranes were consistent (i.e. NaCl <KCl » CaCl2) ranging between 141.2×10−7: 148.2×10−7: 98.2×10−7 cm2/s (±5% for 90% acrylamide based hydrogel) and 2.8×10−7:3.2×10−7:0.7×10−7 cm2/s (±5% for 40% HEMA hydrogel). Conclusions: Ion chromatography enables tear electrolytes to be accurately monitored in 5 l samples. This, coupled with tear envelope sampling, provides a means of correlating clinical signs and symptoms with post-lens electrolyte concentrations and the ion permeability coefficients of individual lenses. Anisa Mahomed completed an MEng in Chemical Engineering and then obtained her PhD from the Biomaterials Research Group at Aston University. Her thesis discussed the aspects of the fabrication of novel hydrogels for dermal and ocular applications. She is currently a postdoctoral researcher and her interests include investigating factors that affect the uptake, release and transport of various species from hydrogels and developing analytical techniques to enable the understanding of clinical adverse events related to the use multipurpose solutions.

Effect of Toric Orthokeratology Lenses on Patients with More Than 1.5 Diopter of Corneal Astigmatism

Results: After wearing lenses, UCVA (log MAR) was significantly improved from 0.93 ± 0.13 to 0.09 ± 0.07 (p < 0.001). Myopia changed from -4.53 ± 1.55 D to -0.67 ± 0.80 D (p < 0.001), refractive astigmatism from -1.48 ± 0.71 D to -0.99 ± 0.72 (p = 0.008) and spherical equivalent from -5.27 ± 1.56 D to -1.12 ± 0.92 D (p < 0.001). Simulated K (Sim K) tended to be more flat (p < 0.001) and the eccentricity was significantly decreased from 0.45 ± 0.08 to -0.69 ± 0.45 (p < 0.001), but corneal astigmatism was not sig- nificantly changed from 2.05 ± 0.41 D to 2.01 ± 0.98 D (p = 0.803). Correlation between corneal astigmatism and lens toricity was statistically significant (r = 0.526, p = 0.012) but not between refractive astigmatism and lens toricity (r = 0.218, p = 0.329). The amount of corneal astigmatism was not correlated with the improvement of uncorrected visual acuity after lens fitting (r = 0.1804, p = 0.399). Conclusions: Toric orthokeratology lenses might be an effective treatment in patients with corneal astigmatism who cannot be fit- ted with spherical orthokeratology lenses. Lens toricity was correlated with corneal astigmatism and the amount of corneal astig- matism did not affect the improvement of uncorrected visual acuity after lens fitting. J Korean Ophthalmol Soc 2015;56(6):830-834

Effect of Toric Orthokeratology Lenses in Patients with Limbus to Limbus Corneal Astigmatism

Purpose: To report the efficacy of toric orthokeratology lenses in patients with astigmatism within 1.5 D having difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. Methods: Twenty-three eyes of 16 patients with limbus-to-limbus corneal astigmatism who had been wearing toric orthokeratology lenses for more than 6 months were recruited. The uncorrected visual acuity (UCVA), refractive error, and keratometric changes including eccentricity before and after wearing lenses were compared, and the correlations between corneal astigmatism as well as refractive astigmatism and lens toricity were assessed. Results: After wearing the lens, UCVA (log MAR) significantly improved from 0.61 ± 0.22 to 0.05 ± 0.08 (p < 0.001). Myopia and spherical equivalent were also reduced significantly (p < 0.001 and p < 0.001, respectively). While Simulated K (Sim K) tended to be more flattened (p < 0.001) and the eccentricity showed significant decrease (p < 0.001), corneal and refractive astigmatism were not changed significantly (p = 0.330 and p = 0.124, respectively). Correlations between corneal and refractive astigmatism and lens toricity were not statistically significant (r = 0.244, p = 0.300; r = -0.051, p = 0.832). No patients showed lens decentration or visual discomfort. Conclusions: Corneal topography was essential in patients who had difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. Toric orthokeratology lenses may be an effective treatment option in patients with limbus-to-limbus corneal astigmatism. J Korean Ophthalmol Soc 2015;56(7):980-984