Contact Lens Research Articles

Patient evaluated economic impact of keratoconus in New Zealand

ABSTRACT Clinical relevance Few studies have investigated the economic burden of keratoconus to patients and society including a patient’s lifetime expenditure. Analysing disease cost is important in advocating funding and planning for appropriate management and treatment. Background Keratoconus can be an expensive disease, including costs associated with visual rehabilitation and surgery. This study aimed to assess direct and indirect expenditures incurred by keratoconus subjects, to estimate the lifetime per capita cost and the total costs of keratoconus per year in Auckland, New Zealand. Methods A cross-sectional study where participants with keratoconus were recruited from public and private clinics to complete an anonymous questionnaire. A keratoconus health expenditure questionnaire was used to assess direct and indirect expenditures for participants. Estimated lifetime per capita costs and total direct and indirect costs associated with keratoconus were calculated. Results Responses from 110 participants were recorded. Most participants (55.5%) were between the ages of 21 and 30, 59.1% were male, and Pacific People were over-represented (14.5%) compared to the national population. The prevalence of visual rehabilitation was low with 74.5% of participants never wearing contact lenses and 32.7% of subjects wearing spectacles purchased over 24 months prior. Few participants (26.5%) had subsidised care, including private health insurance with optical cover or the contact lens subsidy. Total direct and indirect costs are estimated to be NZD 30.9 million per year with an estimated lifetime per capita out-of-pocket cost of NZD 79,254. Conclusion Subjects with keratoconus experience significant direct and indirect costs with limited subsidisation from the government and private health insurance. The significant out-of-pocket costs required for managing keratoconus are likely a significant barrier to accessing appropriate visual rehabilitation in New Zealand.

Therapeutic Contact Lenses for Intraocular Drug Administration: Innovations and Applications in Treating Fungal Keratitis

This review examines the advancements in ocular medication administration, focusing on therapeutic contact lenses (TCLs) as a novel approach for treating fungal keratitis. Traditional eye Drops' bioavailability is poor due to various anatomical and physiological barriers, necessitating frequent administration and leading to poor patient compliance. TCLs offer a promising alternative, providing extended drug release, improved bioavailability, and enhanced patient comfort. This review explores different antifungal drugs, innovative methods for drug incorporation into TCLs, and their therapeutic efficacy. The potential of TCLs to revolutionize ocular drug delivery and improve treatment outcomes for fungal keratitis is discussed.

Advancements in Ocular Therapy: A Review of Emerging Drug Delivery Approaches and Pharmaceutical Technologies

Eye disorders affect a substantial portion of the global population, yet the availability of efficacious ophthalmic drug products remains limited. This can be partly ascribed to a number of factors: (1) inadequate understanding of physiological barriers, treatment strategies, drug and polymer properties, and delivery systems; (2) challenges in effectively delivering drugs to the anterior and posterior segments of the eye due to anatomical and physiological constraints; and (3) manufacturing and regulatory hurdles in ocular drug product development. The present review discusses innovative ocular delivery and treatments, encompassing implants, liposomes, nanoparticles, nanomicelles, microparticles, iontophoresis, in situ gels, contact lenses, microneedles, hydrogels, bispecific antibodies, and gene delivery strategies. Furthermore, this review also introduces advanced manufacturing technologies such as 3D printing and hot-melt extrusion (HME), aimed at improving bioavailability, reducing therapeutic dosages and side effects, facilitating the design of personalized ophthalmic dosage forms, as well as enhancing patient compliance. This comprehensive review lastly offers insights into digital healthcare, market trends, and industry and regulatory perspectives pertaining to ocular product development.

The relationship between contact lens ultraviolet light transmittance and myopia progression: a large-scale retrospective cohort study.

The prevalence of myopia is increasing dramatically around the world, and many studies have suggested the possibility that ultraviolet (UV) light is effective to prevent the onset and progression of myopia. However, UV is a risk factor for diseases that cause refractive errors such as cataract and pterygium. In this study, we evaluated the relationship between UV exposure and myopia progression. The dataset consisted of a total of 337 396 eyes of patients in the 12-to-29-year age range, who were prescribed soft contact lenses (SCL) for refractive error at Okada Eye Clinic in Japan between 2002 and 2011. They were tracked over a five-year period and did not change the type of SCL. In this retrospective cohort study based on medical records, we divided patients into two groups, one prescribed SCL with UV protection (UV-SCL), and another prescribed SCL without UV protection (UV+SCL). Change in refractive power over five years was measured and results compared. It was -0.413 diopter (D) in the UV-SCL group and -0.462 D in the UV+SCL group. Thus, the progression of myopia was slower in the UV-SCL group. The results were also analyzed separately by gender and degree of myopia at the time of initial prescription, which all showed significant differences (P<0.001). Results suggest that UV exposure may advance myopia. Further research is needed to investigate the underlying mechanisms that could explain this.

KeraRing Implantation with Femtosecond Laser in Keratoconus Treatment at Different Stages

Objective: To investigate the reliability and effectiveness of femtosecond laser-assisted KeraRing (Mediphacos, Belo Horizonte, Brazil) implantation in treating keratoconus. Methods: Intrastromal corneal ring segments (KeraRing, Mediphacos, Brazil) were implanted in 15 eyes of 14 patients unable to tolerate contact lenses. Femtosecond laser (Intralase, 60 Hz) was used for corneal tunnel creation. Based on the distribution of ectatic area on the cornea, dual segments were implanted in 9 eyes, while single segments were implanted in 6 eyes. Preoperative and postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), objective and subjective refraction, and topographic corneal curvature (K) values of the cases were compared using the Wilcoxon test. Results: The mean age of patients was 25±7.46 (range: 15-39) years, with a mean postoperative follow-up period of 10.8±7.37 (range: 1-24 months). BCVA improved in all eyes during the follow-up period, increasing from a mean of 0.12±0.1 to 0.38±0.24 (p

Cessation of contact lenses prior to corneal tomography for keratoconus monitoring: results from a clinician survey.

Cessation of contact lenses prior to corneal tomography for keratoconus monitoring: results from a clinician survey.

A Red Alert for Eye Conjunctivitis in Pakistan: A Call for Action and Awareness

For the recent upsurge in the cases of conjunctivitis particularly in Punjab, Pakistan has reached an alarming level. Till September 2023, almost 395,929 cases have been reported only in Punjab because of such an endemic condition schools have been temporarily closed. About 17000 cases were reported alone in Bahawalpur nearly doubling the figures from the previous month but currently, the epicenter of the break is Lahore as the recent outbreaks have also been seen worldwide like Malaysia, Taiwan, Japan, Brazil, and India. The primary cause of the epidemic is coxsackievirusA24 confirmed through genomic analysis. Coxsackievirus A24 is a non-enveloped, positive-stranded RNA virus which produces a polyprotein that forms a structural and non-structural component. This is responsible for acute hemorrhage conjunctivitis which is a viral disease and can spread rapidly as the virus belongs to a highly contagious genotype 4. Its symptoms are redness, pain, irritation discharge from the eye, and light sensitivity with an incubation period of 24 to 48 hours. Transmission can occur through hand-to-eye and eye-to-hand contact of the infected person as well as through contaminated surfaces. As the virus has the belated to evolved rapidly preventive measures are a necessity which include prevention from touching the eyes, practicing regular hand washing, cleaning contact lenses frequently, avoiding the sharing of personal items and using protective eyewear.

Acquired Ankyloblepharon Correction Using Ocular Surface and Tarsal Mucous Membrane Grafting in Cicatrizing Ocular Surface Diseases

Purpose: To report the long-term surgical outcomes of acquired ankyloblepharon correction using mucous membrane graft. Methods: Five eyes of 4 patients (median age, 19 years) with acquired ankyloblepharon were managed using eyelid splitting and mucous membrane graft anchored to the recti muscles on the bulbar surface in the respective quadrant and onto the bare tarsal surface. Outcome measures include a change in the palpebral fissure width, ability to fit scleral contact lenses, visual acuity, and cosmesis. Results: The underlying etiologies of ankyloblepharon were chronic Stevens-Johnson syndrome (n = 3), and chemical injury (n = 2). All 5 eyes had conjunctival shortening, and 3 had severe dry eyes (median Schirmer 4.5 mm). Four eyes had limbal stem cell deficiency. The median horizontal palpebral fissure width improved to 22 mm from 8 mm. This single-staged surgical technique allowed for fornix formation and prosthetic replacement of the ocular surface ecosystem lens fitting in all 5 eyes. Median logMAR visual acuity improved from 2.1 to 0.7 following ankyloblepharon release, prosthetic replacement of the ocular surface ecosystem lens fitting in 4 eyes, and keratoprosthesis in 1 eye. Repeat mucous membrane graft for recurrent symblepharon in 1 quadrant was required in 2 eyes where complete 360 degrees bulbar and tarsal conjunctiva loss were present preoperatively. At the median follow-up period of 27 months, all patients reported better cosmesis and had no symblepharon recurrence following repeat surgery in 2 eyes and single surgery in 3 eyes. The donor site healed well without any complications. No mitomycin C or symblepharon ring was used. Conclusion: Ocular surface and adnexal reconstruction using bulbar and tarsal mucous membrane grafts help visually rehabilitate patients with acquired ankyloblepharon secondary to cicatrizing ocular surface disorders.

Vat photopolymerization of multifunctional fresnel lenses for ocular management.

In this study, multifunctional Fresnel lenses were explored as a potential solution for correcting vision in patients with color vision deficiency (CVD) and high myopia. Current studies have primarily focused on color vision correction through the 3D printing of glasses and contact lenses. However, the potential of 3D-printed multifunctional devices, such as Fresnel lenses, goes beyond addressing a single vision correction issue. For this study, computer-aided design (CAD) model of Fresnel lens with high diopter based on constant height configuration was developed. The CAD model was successfully fabricated using vat photopolymerization 3D printer, employing laboratory-prepared transparent HEMA resin. The resin was modified with two Atto dyes (565nm and 488nm), known for their ability to filter out problematic wavelengths (400-500nm and 540-580nm) to address color vision deficiency. The printed lenses were characterized by their chemical, physical, and optical properties using various characterization techniques. The focusing performance was evaluated using focal length measurements, and the results obtained were less than 2mm deviation from the design value, having the potential to assist in higher myopic vision correction. The resulting optical spectra were compared with commercial glasses, revealing close agreement for CVD correction. These results expand the potential applications of multifunctional Fresnel lenses in ophthalmology, demonstrating their effectiveness as vision-correcting lenses and imaging systems.

Efficacy in myopia control-The impact of rebound.

When myopia control treatment is discontinued, progression will increase, but does it revert to expected values based on the age and race of the child or does it accelerate further? The latter scenario is considered a rebound. A PubMed search was conducted with the words 'rebound' and 'myopia control', identifying further papers from reviews. Inclusion was limited to prospective studies with ≥6 months of treatment, ≥3 months of data following cessation and with axial length data, which allowed calculation of rebound. Nineteen studies were identified, comprising 24 treatment groups. In 10 studies, untreated control children were followed both throughout the treatment and cessation periods, allowing for a concurrent comparison group. In three studies, a control group was followed for 1 or 2 years and thereafter received the treatment under evaluation. Later, treatment ceased in the originally treated children. Finally, six studies were cross-over designs. For these latter two study designs, initial axial elongation and myopia progression in the control group were extrapolated to the cessation period, accounting for annual slowing. Values from durations of <1 year were annualised. The mean annualised rebound was +0.05 ± 0.10 mm and -0.09 ± 0.24 D for axial length and myopia progression, respectively, and these were correlated (r2 = 0.59, p < 0.001). Rebound was associated with 1-year treatment efficacy (r2 = 0.43, p < 0.001). The mean annualised rebound with optical corrections was -0.01 ± 0.03 mm. Five of the six highest rebound values (≥0.14 mm) were from red light therapy and atropine studies. Rebound ranged from +0.03 to +0.14 mm for overnight orthokeratology. Consistent with previous statements, no evidence for rebound was found for myopia control spectacles and soft contact lenses. Future research should explore the influence of age and magnitude of treatment efficacy on rebound.

Characterization of infectious bacterial keratitis in Östergötland County, Sweden: a 10-year retrospective study.

The aim of this study was to characterize bacterial species, aetiology and antibiotic susceptibility connected to bacterial keratitis infections in Östergötland, Sweden. Retrospective cross-sectional study based on electronic health records for the period 2010-2019. Records of patients diagnosed with infectious keratitis were screened for microbiology confirmed infectious bacterial keratitis. Bacterial species and their susceptibility to antibiotics were determined from microbiology test results. One-hundred and ninety patients with lab culture-confirmed infectious bacterial keratitis were included in the analysis. The most frequently found bacterial species were coagulase-negative staphylococci (39%), Staphylococcus aureus (17%) and Cutibacterium acnes (10%). Pseudomonas spp. was the most frequently found Gram-negative bacterial species (7%). Contact lens wear and severely ill/blind eye were the top two aetiologies associated with bacterial keratitis, 22% of the patients with bacterial keratitis were also diagnosed with glaucoma. Most isolates, 157 out of 173, were susceptible to fluoroquinolones, and 145 out of 155 isolates were susceptible to chloramphenicol. Our results revealed a positive rate of bacterial keratitis of 59% for the samples sent to the laboratory. There was a high susceptibility of the bacterial species to the recommended antibiotics. Our results indicate that it is likely that patients are receiving the correct treatment. Future studies are necessary to monitor changes in antibiotic susceptibility.

Innovations in Silicone Hydrogels: Achieving High Oxygen Permeability with Maintained Equilibrium Water Content

Silicone hydrogels are pivotal materials used in contact lenses, biomedicine, and electronic devices, where oxygen permeability and equilibrium water content (EWC) are essential attributes. Generally, an increase in silicone content boosts oxygen permeability but diminishes EWC, presenting a notable trade‐off challenge. In this study, a solvent incorporation method that significantly elevates oxygen permeability without markedly affecting EWC is introduced. Among various solvents, isopropanol incorporation notably enhances oxygen permeability (101 barrer) while maintaining an EWC of 56.0%. This improvement is attributed to enhanced connectivity within the silicone network. Additionally, it is discovered that incorporating siloxane nanoparticles (SNPs) further increases the connectivity of the silicone network, offering a more pronounced improvement in oxygen permeability than solvent alone. However, excessive SNP addition can lead to large phase separation, resulting in decreased transmittance, lower EWC, and increased mechanical strength. Optimizing a transmittance of over 99%, SNP addition achieves a silicone hydrogel with an oxygen permeability of 125 barrer and an EWC of 49.5%, surpassing many advancements reported in the literature.

Ocular Drug Delivery Routes: Diseases Overview and Advanced Administration Methods

The eye is anatomically divided into two: the anterior segment and the posterior segment. The anterior segment comprises structures located at the front of the eye, including the cornea, iris, ciliary body, pupil, aqueous humor, and lens. In contrast, the posterior segment encompasses structures located at the back of the eye, such as the vitreous, retina, choroid, macula, and optic nerves. Numerous diseases arise due to anomalies occurring within these ocular tissues. When formulating drugs for ocular conditions, it is crucial to consider the specific segment of the eye affected by the disease. Various routes of drug administration and dosage forms are available for delivering medications to the eye. These include topical forms such as solutions, emulsions, suspensions, ointments, and gels. Additionally, drugs can be administered through routes such as intravitreal, suprachoroidal, intracorneal, or subconjunctival. Furthermore, novel methods of drug delivery to the eye have emerged, including inserts, films, contact lenses, and microneedles. The aim of this review is to discuss innovative drug delivery systems and explain in detail the different routes of drug administration to the eye with examples from the current literature.

Antimicrobial and antifouling hyaluronic acid-cobalt nanogel coatings built sonochemically on contact lenses

The wearing of contact lenses (CLs) may cause bacterial infections, leading in turn to more serious complications and ultimately vision impairment. In this scenario, the first step is the adhesion of tear proteins, which provide anchoring points for bacterial colonization. A possible solution is the functionalization with an antimicrobial coating, though the latter may also lead to sight obstruction and user discomfort. In this study, adipic acid dihydrazide-modified hyaluronic acid-cobalt (II) (HA-ADH-Co) nanogels (NGs) were synthesized and deposited onto commercial CLs in a single-step sonochemical process. The coating hindered up to 60 % the protein adsorption and endowed the CLs with strong antibacterial activity against major ocular pathogens like Staphylococcus aureus and Pseudomonas aeruginosa, reducing their concentration by around 3 logs. Cytotoxicity assessment with human corneal cells demonstrated viabilities above 95 %. The nanocomposite coating did not affect the optical power and the light transmission of the CLs and provided enhanced wettability, important for the wearer comfort.

Fluid confinement within a branched polymer structure enhances tribological performance of a poly(2-methacryloyloxyethyl phosphorylcholine)-surface-modified contact lens.

The poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-modified, silicone hydrogel, contact lens (CL) material lehfilcon A has previously been demonstrated to have a lubricious, antifouling and ultra-soft surface. This study provides confirmatory identification of the outer polymer structures on this CL surface as branched PMPC structures. It further aims to understand their role in providing enhanced tribological performance via fluid confinement. A combination of scanning transmission electron microscopy and atomic force microscopy infrared spectroscopy has been used to achieve both morphological and chemical confirmation of branched PMPC structures resembling the polysaccharide species present on the surface of the cornea. Measurements of the fluid-confinement behaviour of this layer, by means of nanoindentation experiments, show it to resist squeeze-out of the interstitial fluid, thereby boosting lubrication by virtue of a fluid-load-support mechanism. Tribological testing of CLs showed this effective lubrication to be maintained after one month of daily wearing.

Assessing Prevalence and Severity of Dry Eye Disease Across Various Types of Allergic Conjunctivitis

Background: Allergic conjunctivitis (AC) is a prevalent ocular condition triggered by environmental allergens, causing significant discomfort and reduced quality of life. Dry Eye Disease (DED), marked by ocular discomfort and visual disturbances, frequently overlaps with AC symptoms. This study examines the prevalence of DED in AC patients and explores the relationship between different AC types and DED severity. Method: A cross-sectional, observational study was conducted from June to September 2023 in the Department of Ophthalmology at a tertiary center in North India. A total of 264 AC patients aged 18 years and older with itchy eyes were included. Patients with contact lens use, recent ocular surgery, trauma, corneal pathology, or certain systemic diseases were excluded. DED was assessed using the Ocular Surface Disease Index (OSDI), Schirmer’s test, and Tear Film Break-Up Time (TFBUT). Results: DED was found in 70% of AC patients, with 20% mild, 19% moderate, and 32% severe cases. Females were more affected (64%). VKC patients showed higher tear production and better TFBUT scores. PAC patients had the most severe DED. Conclusion: DED is common in AC patients, with PAC associated with more severe DED, while VKC shows milder symptoms. Tailored treatment approaches are needed for managing AC and DED.

Corneal endothelial density and morphology in long-term soft contact lens users in Japan: a retrospective cross-sectional study of 17,732 eyes

Purpose There is a lack of long-term and large-scale studies on the adverse effects of soft contact lenses (SCLs) on the corneal endothelia of Asian populations. Here, we aimed to examine the effects of long-term SCL use on corneal endothelial density and morphology. Materials and Methods This retrospective study involved consecutive patients at the Miyata Eye Hospital (Miyazaki, Japan), who had used SCLs for more than 1 year. Patients with ophthalmological disorders without refractive errors were excluded. The period of SCL use, SCL type, corneal endothelial cell density (ECD), appearance rate of hexagonal cells (HEX), and coefficient of variation of cells (CV) were analyzed. Results In total, 17,732 eyes of 8866 patients were included in the analysis (age, 26.0 ± 8.8 years). The mean period of SCL use was 6.3 ± 5.4 years. Multivariate regression analysis revealed that ECD and HEX were significantly negatively correlated with the period of SCL use, age, and sex (p < 0.001 for all). The CV was significantly positively correlated with the period of use (p < 0.001), sex (p = 0.002), and age (p < 0.001). Conclusions Corneal ECD, HEX, and CV were significantly associated with the period of SCL use in long-term users. It is essential to regularly check the corneal endothelium in patients with a history of long-term SCL use.

4D-printed photochromic contact lenses for ultraviolet monitoring and protection

4D-printed photochromic contact lenses for ultraviolet monitoring and protection

Corneal Curvature Change After Strabismus Surgery: An Experience from a Single-academic Center

Objective: This study aimed to explore corneal curvature changes following strabismus surgery using a quadric surface fitting model to address ocular misalignment. Material and Methods: In this prospective cross-sectional study, 54 completed cases (84 eyes) of patients aged 6–60 years old (mean 10 years old) undergoing horizontal rectus muscle surgery were examined using placido-based keratometry with the Oculus Keratograph 5M system. Data on corneal curvature were collected one week pre-operation, and again one week, one month, and three months post-operation. Asphericity in the vertical meridian (Qy) and horizontal meridian (Qx), and surgical-induced astigmatism (SIA) were calculated. Results: The 84 eyes included were categorized into three groups: horizontal muscle surgeries, oblique muscle surgery, and combined horizontal and oblique muscle surgeries. Significant corneal prolation (steep central, flat peripheral) was revealed in the vertical meridian (Qy) at 3 months postoperatively for lateral rectus (LR) recession in the first group (p &lt; 0.001), and the mean SIA was 0.45 D (95% CI: 0.35–0.56 D). A similar effect was seen in the vertical meridian of the third group (p &lt; 0.01), with a mean SIA at 3 months of 0.27 D (95% CI: 0.23–0.32 D). Conclusion: Lateral rectus muscle recession induces corneal vertical prolation for up to 3 months post-operation. Surgeons are thus advised to re-evaluate refraction and defer contact lens refitting, refractive surgery, and intraocular lens calculations for at least 3 months after the procedure.

Change in Tear Layer Thickness under Scleral Contact Lenses in Keratoconus Patients and Normal Cornea Volunteers

Objective: To quantify rate of post-lens tear thickness change under scleral contact lenses in keratoconus patients and normal cornea volunteers. Materials and Methods: We conducted a prospective observational study where semi-scleral lenses were fitted to 20 eyes (5 subjects, 10 eyes in each group). After insertion, post-lens tear thickness was measured at 0, 30 minutes and every hour up to 6 hours using Anterior Segment OCT. To analyze post-lens tear thickness and its rate of change at each time point, both within and between groups, a linear mixed model was used. Results: The initial mean post-lens tear thickness (µm) was 742 ± 50 and 440 ± 50 in keratoconus and normal cornea group, respectively. The mean rate of change (µm/hr) was highest in the first 30 minutes in both groups (80.8 ± 8.7, 132.2 ± 8.8 in keratoconus and normal cornea group). Following the first four hours in keratoconus and the first hour in normal cornea group, the reduction rate in post-lens tear thickness exhibited no statistically significant difference from the rate of change observed during the 5-6 hour period. The mean percentage of total change over 6 hours after lens insertion was higher in normal cornea compared to keratoconus group (36.6% vs 22.5%). Conclusion: The reduction in post-lens tear thickness follows a nonlinear pattern. The mean rate of change was highest after insertion and remained stable after four hours in keratoconus and one hour in normal cornea group. The percent change over the 6-hour period was greater in normal cornea group.