Crystalline Lens Transparency Research Articles

Double-step calculation of the intraocular lens power in lens opacities excluding the measurement of axial eye length by optical biometry. A clinical case

The main source of intraocular lens (IOL) power calculation errors in phacoemulsification (PE) is axial length (AL) measurement inaccuracy in cases if optical biometry cannot be used.bto describe an original double-step method of IOL power calculation in lens opacities which exclude AL measurement with optical biometry.Material and methods. Patient S. (male, 71) with a bilateral immature cataract underwent right eye phacoemulsification (PE) with no IOL implantation. After that, AL was measured in the aphakic state with transparent optical media and used in combination with preoperative anterior segment biometry data to calculate the IOL power. In the second stage, a selected lens with an extended focus range was implanted.Results. The patient was examined and discharged on the second day after surgery with visual acuity OD 0.3 sph +0.25 cyl -0.75 ax150 = 0.5 and signs of moderate postoperative keratopathy. After 2 weeks, uncorrected visual acuity was as high as 0.9 and could not be further corrected by spectacle lenses. The patient was admitted for surgical treatment of the left eye cataract and also operated in two stages. The AL measured by the optical method in the aphakic state, was 0.31 mm less than that measured before the operation. Six months after PE with IOL implantation, distance visual acuity in both eyes was 1.2, the patient could use binocular vision for reading and PC work with no difficulty.Conclusion. The double-step approach to IOL power calculation is justified in cases of strong decrease of crystalline lens transparency, especially in complicated cases, for example, in high myopia or “premium” lens implantation, in which patients are especially sensitive to correct target refraction, even though this approach requires a delayed IOL implantation, which should take place after a precise calculation of AL taken in the aphakic state.

Long-term changes in crystalline lens transparency after accelerated transepithelial corneal cross-linking in patients with keratoconus.

To investigate the long-term clinical outcomes and changes in crystalline lens transparency after accelerated (45 mW/cm2) transepithelial corneal cross-linking (ATE-CXL) using the Pentacam imaging system in patients with progressive keratoconus. The study prospectively included 44 keratoconus eyes of 40 patients (mean age: 24.39 ± 5.61 years) who underwent ATE-CXL. The examinations, including assessment of uncorrected distance visual acuity, corrected distance visual acuity, corneal topography, and corneal endothelial cell density count, were conducted preoperatively and 1 month, 3 months, 6 months, 1 year, and 5 years postoperatively. Measurement of crystalline lens density using Pentacam images was also performed pre- and postoperatively. All surgeries were uneventful with no postoperative complications. All keratometry values and corneal thickness remained stable during the 5-year follow-up period (all p > 0.05). There were no significant differences in corneal endothelial cell density count, visual acuity, and anterior average lens density in the 0.5-, 1.0-, and 1.5-mm depth zones during the 5-year follow-up period compared with the preoperative values (all p > 0.05). The results of this study suggest that ATE-CXL at 45 mW/cm2 is safe and effective for the treatment of progressive keratoconus in terms of both crystalline lens density and endothelial cell density.

Polygenetic-Risk Scores Related to Crystallin Metabolism Are Associated with Age-Related Cataract Formation and Interact with Hyperglycemia, Hypertension, Western-Style Diet, and Na Intake.

Age-related cataract (ARC) development is associated with loss of crystalline lens transparency related to interactions between genetic and environmental factors. We hypothesized that polygenetic risk scores (PRS) of the selected genetic variants among the ARC-related genes might reveal significant genetic impacts on ARC risk, and the PRS might have gene–gene and gene–lifestyle interactions. We examined the hypothesis in 1972 and 39,095 subjects aged ≥50 years with and without ARC, respectively, in a large-scale hospital-based cohort study conducted from 2004 to 2013. Single nucleotide polymorphisms (SNPs) of the genes related to ARC risk were identified, and polygenetic risk scores (PRS) were generated based on the results of a generalized multifactor dimensionality reduction analysis. Lifestyle interactions with PRS were evaluated. The PRS derived from the best model included the following six SNPs related to crystallin metabolism: ULK4_rs1417380362, CRYAB_rs2070894, ACCN1_rs55785344, SSTR2_rs879419608, PTN_rs322348, and ICA1_rs200053781. The risk of ARC in the high-PRS group was 2.47-fold higher than in the low-PRS group after adjusting for confounders. Age, blood pressure, and glycemia interacted with PRS to influence the risk of ARC: the incidence of ARC was much higher in the elderly (≥65 years) and individuals with hypertension or hyperglycemia. The impact of PRS on ARC risk was greatest in middle-aged individuals with hypertension or hyperglycemia. Na, coffee, and a Western-style diet intake also interacted with PRS to influence ARC risk. ARC risk was higher in the high-PRS group than in the low-PRS group, and high Na intake, Western-style diet, and low coffee intake elevated its risk. In conclusion, ARC risk had a positive association with PRS related to crystallin metabolism. The genetic impact was greatest among those with high Na intake or hypertension. These results can be applied to precision nutrition interventions to prevent ARC.

Long-term assessment of crystalline lens transparency in eyes implanted with a central-hole phakic collamer lens developing low postoperative vault.

To assess long-term crystalline lens transparency in eyes implanted with phakic collamer intraocular lens (pIOL) with a central port and low postoperative vault for correction of myopia. Clinica Baviera, Madrid, Spain. Retrospective cross-sectional single-center study. Using a noninvasive Fourier-domain swept-source anterior segment optical coherence tomography system, shifts in myopic and astigmatic myopic eyes implanted with a pIOL with vaulting lower than 100 μm in miosis and more than 4 years of follow-up were dynamically evaluated. Main outcome measures were pIOL dynamic vault (vault interval and vault range [VR]), crystalline lens density, and anterior subcapsular lens opacities. Crystalline lenses were examined under slitlamp microscopy, and lens density was evaluated using quantitative Scheimpflug images. Scheimpflug images were compared with those of a control group comprising eyes that were candidates for pIOL implantation. The study population comprised 24 eyes from 16 patients previously implanted with a pIOL (5.82 ± 0.9 years) with central vault lower than 100 μm under photopically induced miosis. The mean vault value was 52 ± 19 µm under photopic light conditions and 113 ± 37 µm under scotopic conditions. The mean VR was 58 ± 24 μm. Anterior subcapsular lens opacities were found in only 1 eye (4.17%). The mean lens density was 7.94 ± 0.43, and no statistically significant differences were observed compared with the control group. Long-term low vaulting in eyes implanted with a pIOL with a central port for correction of myopia was associated with a low risk for developing anterior crystalline lens opacities.

A-scan ultrasonic system for real time automatic cataract detection

Cataract is an ocular condition associated to the loss of the normal crystalline lens transparency, and its progression can result in a total loss of vision. The gold standard diagnostic method consists on qualitative observation through a slit lamp. This method has two limitations: incipient cataract may not be detected and the cataract hardness is subjectively evaluated. It may delay the diagnosis, or result on phacoemulsification surgeries complications when cataract hardness is not correctly estimated. On this study we present a new prototype for objective cataract detection and characterization, based on ultrasounds. The Eye Scan Ultrasonic System (ESUS) acquires A-scan signals at a nominal frequency of 20 MHz. The lens interfaces can be automatically detected in real time, based on the analysis of signal energy levels. The detection and characterization of cataract type and severity is done by an automatic classification algorithm based on features extracted in time and frequency domain. The system performance has been tested on preclinical data, and the beginning of clinical studies is expected shortly.

Blue Light Hazard: are exposure limit values protective enough for newborn infants?

Blue Light Hazard is an emerging concern for health of population. Nevertheless, acute exposure to blue rays from artificial light is well taken into account by normative requirements applicable to lamps engineering and risk for general population is low. There is also no evidence for a chronic effect of artificial lighting on retina for general population at radiance below exposure limit values. That said, children in the very first years of life constitute a specific population to consider. On one side, eye anatomy of very young infants is different from elder young people or adults. On the other side, infants can be in close contact with some luminous toys or night lights. This paper presents a first approach for taking into account the specific anatomy of newborn infants’ eyes in blue light hazard evaluation. Results show that differences of crystalline lens transparency, focal length and pupil diameter could induce a significantly higher retinal exposure than for adult.

Structural and Functional Properties, Chaperone Activity and Posttranslational Modifications of Alpha-Crystallin and its Related Subunits in the Crystalline Lens: N-acetylcarnosine, Carnosine and Carcinine act as Alpha- Crystallin/Small Heat Shock Protein Enhancers in Prevention and Dissolution of Cataract in Ocular Drug Delivery Formulations of Novel Therapeutic Agents

Cataract is a leading cause of blindness worldwide and is responsible for ∼40-80% of the estimated 45 million cases of blindness that occur across the globe. In addition to providing refractive properties to the lens for focusing the image, it is believed that the molecular chaperone function of α-crystallin is essential in preventing the light scattering due to aggregation of other proteins and thus in the maintenance of lens transparency and thereby prevention of cataract. By now, it is fairly acknowledged that chaperoning ability of α-crystallin is instrumental in the maintenance of crystalline lens transparency, and decreased chaperone-like activity of α-crystallin is associated with various types and stages of cataract. A better pharmacological targeting of safeguarding the α-crystallin chaperone activity may aid the development of therapeutic strategies that could evade the need for cataract surgery and revive lens transparency of the cataractous lenses. This article originally summarizes the significance of modulation and enhancing of α-crystallin chaperone activity with imidazole-containing dipeptides N-acetylcarnosine, carnosine and carcinine in consequence to prevent, delay or dissolve the human cataract. A growing evidence and discussion of recent patents are presented in this study that demonstrate the ability of N-acetylcarnosine (lubricant eye drops) or carcinine (lubricant eye drops) (universal antioxidant and deglycation agent) resistant to enzymatic hydrolysis with carnosinase to act as pharmacological chaperones, to decrease oxidative stress and ameliorate oxidative and excessive glycation stress-related eye disease phenotypes, suggesting that the field of chaperone therapy might hold novel treatments for age-related cataracts, age-related macular degeneration (AMD) and ocular complications of diabetes (OCD). The therapeutic strategies are highlighted in the study for identifying potential chaperone compounds and for experimentally demonstrating chaperone activity in in vitro and in vivo models of human age-related eye disease, such as cataracts and advanced glycation tissue proteins - engineered systems.

Collagen Cross-Linking With Riboflavin in a Femtosecond Laser–Created Pocket in Rabbit Corneas: 6-Month Results

To evaluate the initial changes of normal rabbit corneas after collagen cross-linking (CXL) with a femtosecond laser. Experimental study in animal eyes. The right eyes of 10 male New Zealand white rabbits were treated with CXL with a femtosecond laser. A femtosecond laser was used to create an intrastromal pocket with 80-μm depth and 7-mm diameter. Intrastromal administration of 0.1% riboflavin solution was made into the femtosecond laser-created pocket and the cornea was irradiated with 3 mW/cm(2) ultraviolet A (UVA) light of mean 370 nm wavelength for 10 minutes. The corneal topography and pachymetry were evaluated by the Pentacam. All observations were performed preoperatively and at postoperative day 1, week 1, week 2, and months 1, 3, and 6. Light microscopy was applied to observe changes in the cornea at postoperative month 6. Cornea healing postoperatively was uneventful in all cases. The central corneal thickness (CCT) in the treated rabbit cornea reached the peak value at postoperative day 1, which descended gradually to the minimum at month 1 and returned to a high level at postoperative months 3 and 6. The CCT data postoperatively was significantly thicker than that preoperatively, except at postoperative month 1 (P > .05). Steepening of the operative area was found at the corneal front at postoperative day 1, which recovered dramatically after only 1 week. Then the treated area gradually flattened over the course of follow-up. In 8 of 10 rabbits, a demarcation line-like change in the stroma was visible in the Scheimpflug image at slightly increased contrast as early as 1 month after CXL treatment. The micromorphologic examination also confirmed the existence of the demarcation line. Crystalline lens transparency remained unchanged all the time. CXL with a femtosecond laser appears to be safe. The cornea can realize a faster, uneventful recovery. The stromal demarcation line may be a direct clinical sign to detect an effective corneal cross-linking during the early phase postoperatively.

Traumatic cataract and other adverse events with the implantable contact lens

To evaluate the surgical outcome and adverse events associated with implantation of the implantable contact lens (ICL) for the correction of high myopia or high hyperopia. Helsinki University Eye Hospital, Helsinki, Finland. In this nonrandomized prospective clinical trial, the ICL V4 was implanted in 26 eyes of 13 patients with normal enrollment criteria (younger than 45 years, a clinically clear crystalline lens) (Group 1) and the V2, V3, or V4 were implanted in 38 eyes of 22 patients with heterogeneous criteria (older than 45 years or opacities in the crystalline lens) (Group 2). The main outcome measures were lens opacity classification system (LOCS II) assessment and transparency analysis of the lens. In Group 1, microdensitometric assessment showed no decrease in crystalline lens transparency and no statistically significant increase in crystalline lens density at any follow-up examination (P>.05). The incidence of anterior subcapsular (AS) opacities was 7.7%, and no eye developed clinically significant cataract during the mean follow-up of 13.2 months +/- 12.3 (SD). No myopic eye lost a line of best corrected visual acuity (BCVA); 50.0% of hyperopic eyes lost 1 line of BCVA. Sixty-eight percent of myopic eyes and 75.0% of hyperopic eyes were within +/-1.0 diopter of the predicted refraction. In Group 2, the incidence of AS opacities was 47.4% and 10 eyes (26.3%) developed clinically significant cataract during the mean follow-up of 30.9 +/- 18.0 months. The visual and refractive results were similar to those in Group 1 at 1 month, but due to progressive AS opacities in the crystalline lens, 23.4% of eyes lost BCVA lines during the follow-up. Intraoperative complications were few and insignificant. Implantation of the ICL for correction of high myopia or high hyperopia appears to be a safe procedure with good visual and refractive results immediately. There was no decrease in the transparency or increase in the density of the crystalline lens with the latest generation of the ICL device in the normal group, indicating enhanced safety. Progressive lens opacification in the heterogeneous group shows there are risk factors for cataract formation; ie, type V3 ICL, preexisting lens opacities, and older patient age. Anterior subcapsular opacities are most likely the result of trauma.

Ocular refractive changes in patients receiving hyperbaric oxygen administered by oronasal mask or hood.

The aim of this study was to quantify ocular refractive changes after a standard hyperbaric oxygen (HBO) treatment protocol and to characterize the time period of recovery. Hyperbaric oxygen therapy was given for 90 min daily at a pressure of 240 kPa for 21 days. Oxygen was administered to 20 patients using an oronasal mask and to 12 patients using a hood. Follow-up examinations were carried out 2-4 days after treatment, and thereafter regularly for up to 10 weeks in both groups. Refraction was assessed automatically and by the monocular subjective refraction method. A subgroup of nine of the 20 patients to whom oxygen was administered by an oronasal mask underwent a separate eye examination, which included crystalline lens opacity measurements and LOCS III gradings. In the patients given oxygen by mask, there was a significant myopic shift in the mean spherical equivalent, which was largest 2-4 days after treatment. The shift was - 0.55 +/- 0.40 D in the right eye and - 0.53 +/- 0.42 D in the left eye. In the patients given oxygen by hood, the largest shift was observed after 12-16 days, and was - 1.06 +/- 0.52 D in the right eye and - 1.10 +/- 0.57 D in the left eye. The refractive changes returned to baseline 6 weeks and 10 weeks after HBO treatment, respectively. No significant changes in crystalline lens transparency were revealed. The myopic shift after HBO therapy recovers within 10 weeks and may be more pronounced when patients are given oxygen using a hood compared with using an oronasal mask.

Lente fácica de câmara posterior para correção da miopia

Objetivo: Avaliar a eficácia, previsibilidade e segurança do implante de lente intra-ocular de câmara posterior em pacientes com miopia moderada e elevada. Métodos: Analisamos os resultados das cirurgias realizadas em 93 olhos de 54 pacientes para implante de lente fácica de câmara posterior com a finalidade de corrigir miopia moderada e elevada. O objetivo da cirurgia era a emetropia. O acompanhamento médio foi de 9 meses, variando de 1 a 38 meses (desvio padrão 10,45). Resultados: O equivalente esférico médio pré-operatório era -13,56 D (variando de -5,75 a -20,38 D) e o equivalente esférico médio pós-operatório no último exame foi -0,92 D (variando de -3,88 a +1,00 D). No último exame, 39 olhos (41,9%) se encontravam entre ±0,50 D da emetropia, 64 olhos (68,8%) estavam entre ±1,00 D e 88 olhos (94,6%) estavam entre ±2,00 D da emetropia. Um ganho de duas ou mais linhas de visão foi observado em 45,17% (42 olhos). Em 15 olhos (16,1%) ocorreu algum tipo de complicação: em 2 olhos (2,2%) houve perda de células endoteliais, em 2 olhos (2,2%) ocorreu bloqueio pupilar e em 11 olhos (11,8%) houve alterações de transparência lenticular, assintomática em 5 olhos (5,4%) e sintomática em 6 olhos (6,5%). Conclusão: O implante de lente fácica de câmara posterior para correção de miopia moderada e alta é um método eficaz, previsível e seguro. O significativo ganho de linhas de visão é uma observação freqüente nesta técnica. Um acompanhamento pós-operatório mais prolongado em um maior número de pacientes é necessário para confirmar a estabilidade dos resultados a longo prazo.