Rigid Gas Permeable Contact Research Articles

Multifocal Rigid Gas Permeable Contact Lenses with Multi-Tangential Positioning and Corrected Spherical Aberration for Myopia Control

Slowing the progression of myopia has become an extensive concern for parents of children with myopia. According to research findings in animals, eye growth is primarily influenced by the peripheral retina. Treatment options such as orthokeratology, daytime bifocal or multifocal soft contact lens usage are available because they can induce relative myopia in the periphery. In this work, a new multifocal rigid gas permeable (MFRGP) contact lens for myopia prevention and control in adolescents was designed specifically for preventing and controlling myopia in adolescents. This lens features a multi-tangent alignment curve, smaller spherical aberration, and transition defocus. FocalPoints and UPC 100 Vision were used for lens design and lathing, respectively. The lens structure and power profile were measured using IS830 and CONTEST 2, respectively. The elimination of lens aberrations was achieved through design optimization using ZEMAX with ray tracing. Lens fitting was evaluated using slit-lamp microscopy and corneal topography.

Referral Pattern and Comanagement of Patients With Keratoconus in West Africa: A Survey-Based Study of Optometrists in Ghana and Nigeria.

To investigate the referral and management patterns of patients with keratoconus among primary eye care practitioners in Ghana and Nigeria. A questionnaire adapted from previous studies was modified and created using Google Forms. The online survey was distributed to prospective participants using e-mails and other social media platforms. Data were analyzed using the Statistical Product and Service Solutions software (version 25.0; IBM Corp, Armonk, NY; Released 2017). One hundred and sixty-nine optometrists responded to the survey (61.54% from Nigeria and 38.46% from Ghana). Most (88.6%) practiced without corneal topographers. Most respondents (77.7%, n=136) reported not fitting rigid gas-permeable (RGP) contact lenses in a year and 68% were willing to refer for contact lens fitting to another practitioner. The major barriers to RGP fitting were lack of experience (44.4%, n=72), cost to practice (15.4%, n=25), and other reasons (12.4%), whereas 27.8% (n=45) preferred not to answer. Seventy-six percent of respondents (n=133) were willing to fit RGPs if the respondents received the training to do so. About half of the respondents (53.8%) reported progression of cornea signs as the reason for referral to an ophthalmologist. Half of the respondents (n=51.4%) did not have a cornea surgeon in the area the respondents practiced, and 76.3% reported not comanaging patients at all with ophthalmologists. This study highlights the current standard of care of patients with keratoconus in West Africa. The findings from this study suggest that clinical guidelines and further training of eye care practitioners in West Africa are needed to better manage patients with keratoconus.

Keratoconus.

Keratoconus is a progressive eye disorder primarily affecting individuals in adolescence and early adulthood. The ectatic changes in the cornea cause thinning and cone-like steepening leading to irregular astigmatism and reduced vision. Keratoconus is a complex disorder with a multifaceted aetiology and pathogenesis, including genetic, environmental, biomechanical and cellular factors. Environmental factors, such as eye rubbing, UV light exposure and contact lens wearing, are associated with disease progression. On the cellular level, a complex interplay of hormonal changes, alterations in enzymatic activity that modify extracellular membrane stiffness, and changes in biochemical and biomechanical signalling pathways disrupt collagen cross-linking within the stroma, contributing to structural integrity loss and distortion of normal corneal anatomy. Clinically, keratoconus is diagnosed through clinical examination and corneal imaging. Advanced imaging platforms have improved the detection of keratoconus, facilitating early diagnosis and monitoring of disease progression. Treatment strategies for keratoconus are tailored to disease severity and progression. In early stages, vision correction with glasses or soft contact lenses may suffice. As the condition advances, rigid gas-permeable contact lenses or scleral lenses are prescribed. Corneal cross-linking has emerged as a pivotal treatment aimed at halting the progression of corneal ectasia. In patients with keratoconus with scarring or contact lens intolerance, surgical interventions are performed.

Compliance with rigid gas-permeable contact lens use in children younger than 6 years in China: a 6-year retrospective study.

To explore the abandonment rate and factors influencing the use of rigid gas-permeable contact lenses (RGPCL) among children aged < 6 years. This retrospective case series study included 70 children aged < 6 years who were fitted with RGPCL for visual rehabilitation between January 2016 and December 2021. We collected data on indications, discontinuation rates, and reasons for discontinuation from medical records and via telephone calls and investigated the factors influencing contact lens abandonment. The median age of the 70 participants was 5.0 (interquartile range: 4.0-5.9) years. Further, 36 (51.4%) children stopped wearing contact lenses; among them, 17 (47.2%) stopped within 3 months, and the median duration of lens wearing was 4.0 (interquartile range: 1.0-11.5) months. Additionally, there was a correlation between the duration of lens wearing and lens abandonment (r = -0.698, P < 0.001). A high parental education level (hazard ratio [HR] = 0.425; 95% confidence interval [CI] 0.198, 0.913; P = 0.028) was a protective factor against lens abandonment, while parental assessment indicating harder than expected practicality (HR = 4.062; 95% CI 1.204, 13.707; P = 0.024) was a risk factor for abandonment. Children aged < 6 years are susceptible to early discontinuation of RGPCL use. Since parents perform daily lens manipulation, they are crucial to the continuity of lens use in these children. To improve RGPCL use continuity, communication and supervision should be strengthened before and after RGPCL fittings.

Kontaktlinsenversorgung bei ausgeprägter Sicca bei vermuteter Alakrimie bei einem sechsjährigen Kind

Purpose. The aim of this case report is to describe a case of suspected alacrimia in a six-year-old child that resulted in irregular astigmatism with risk of amblyopia. A specialty contact lens fitting for visual rehabilitation was performed. Material and Methods. Different wearing modes (extended wear and daily wear) as well as contact lens types (soft silicone hydrogel contact lenses of different wearing rhythms, as well as rigid gas permeable (RGP) contact lenses were fitted. Results. In this case, different contact lens types (soft and rigid contact lenses) could not achieve a satisfactory treatment result. However, a piggyback contact lens system with daily wear was a good treatment solution. Conclusion. Irregular astigmatism in children is always a high risk of amblyopia. For this reason, timely optical treatment for visual rehabilitation is a high priority. Sometimes it is necessary to combine different contact lenses and wearing modalities to achieve the best solution for a complex treatment situation. Keywords: ALACRIMIA, HYPOLACRIMIA, SICCA, IRREGULAR ASTIGMATISM, VISUAL REHABILITATION, AMBLYOPIA RISK

Longitudinal assessment of the progression of severe keratoconus based on corneal topography

We aimed to assess long-term disease progression in patients with severe keratoconus (KC). Clinical records of 125 patients (201 eyes) with severe KC followed-up for > 12 months were retrospectively analyzed. From these, 28 patients (31 eyes) were included. Corneal topography parameters evaluated included thinnest corneal thickness (TCT), maximum keratometry (Kmax), anterior and posterior mean corneal radii of 3 mm (aKM, pKM), steep keratometry, and KC screening indices. All patients wore rigid gas permeable contact lenses (RGPCLs) for an extended period. The median patient age and follow-up period were 20 (interquartile range [IQR] 17–22) years and 25 (15–38) months, respectively. Compared to baseline, the aKM, Kmax, and KC screening indices on the anterior corneal surface were reduced at the final follow-up (P < 0.05). No changes were observed in RGP-corrected visual acuity, TCT, pKM, or KC screening indices on the posterior corneal surface. The higher the baseline value, the greater the reduction in aKM and Kmax. Five patients (16%) experienced disease progression during follow-up. Patients with severe KC showed reduced anterior corneal surface curvature and no change in corneal thickness during an average follow-up period of 2–3 years while wearing RGPCLs.

Visual outcome in Keratoconus with spherical rigid gas permeable contact lens

Introduction: Keratoconus is a bileteral asymetric progressive ecteria of cornea commonly associated with vernal keratoconjunctivitis and Atopic dermatitis. Rigid gas permeable (RGP) contact lens is the first choice for refractive correction in keratoconic eyes. The visual outcome in Keratoconus with spherical RGP contact lens along with the mean age of presentation, gender predominance, ethnicity, associated conditions, refractive error and corneal astigmatism was evaluated. Methods: The records of the Keratoconus patients attending cornea and contact lens clinic for last 6 years were reviewed and analyzed using SPSS-14 software. Data on laterality, race, age, gender, refractive error, visual acuity (VA), associated conditions and contact lens parameters were obtained. A total of 22 patients with 38 keratoconic eyes were included in the study. Results: The mean age of Keratoconus presentation was 18.11 ± 4.45 years. Sixteen cases (72.73 %) were bilateral; 6 (27.27 %) were unilateral. Mean uncorrected visual acuity (UCVA) was 0.86 ± 0.40 Log MAR. Mean spectacle visual acuity was 0.54 ± 0.38 Log MAR. Mean visual acuity with spherical RGP contact lenses was 0.08 ± 0.14 Log MAR. The difference between mean spectacle visual acuity and mean VA with spherical RGP contact lens was statistically significant (p &lt; 0.001). Conclusion: In all stages of Keratoconus, improvement in visual acuity with spherical RGP contact lens was highly significant.

Correction of Internal Astigmatism Using Toric Scleral Contact Lens after Implantable Collamer Lens Surgery

Purpose: We present a case of internal astigmatism correction using a toric scleral contact lens in a patient with high myopia after implantable collamer lens (ICL) surgery.Case summary: A 45-year-old man presented with a significant decrease in visual acuity despite previous ICL surgery. Initial attempts to fit a corneal rigid gas permeable contact lens to the left eye were unsuccessful due to fitting challenges. Subsequently, the use of a spherical scleral contact lens effectively corrected corneal astigmatism but failed to address internal astigmatism, thereby limiting improvement in visual acuity. Postoperative corneal ectasia and ICL rotation were suspected to be the underlying causes of this astigmatism. The introduction of a front toric scleral lens resulted in a significant improvement in visual acuity and sustained comfort throughout the 3-month follow-up period.Conclusions: The use of toric scleral lenses can significantly improve visual acuity and provide exceptional comfort in cases where corneal morphology and lens position change after ICL surgery. This modality presents a promising alternative for future consideration.

Biomechanical evaluation of different plunger size and plunger position on removing soft contact lenses and rigid gas permeable contact lenses.

To avoid risks of mucosal infection from contact lenses removal, a contact lens plunger is often used. Given various types of contact lens plungers available on the market, no study has yet been done on mechanical effects of the contact lens plunger on contact lens removal. Here, this study used finite element analysis to investigate the effects of plunger size and plunger position on the removal of soft and rigid gas permeable (RGP) contact lenses. First, we established finite element analysis models for the plunger, contact lens, cornea, and aqueous humor. The plunger is made of mostly silicone rubber, and the contact lenses are mainly made of soft and hard material. The part of the plunger used for removal was located either at the central or the edged position, with pulling 1 mm distance. The main parameters observation indicators of in this study were the reaction force at the fixed end of the cornea, aqueous humor, the von Mises stress of the plunger, the contact lenses, and the cornea. Results of this study showed that when a plunger of a larger diameter was used, the reaction force of the plunger was also larger, especially when applied to RGP lenses, which required a slightly larger force (∼0.27 N). Also, when removing a RGP lens from the edge, there was a greater stress at the edge of the contact lens (2.5799 MPa), and this caused a higher stress on both the cornea (0.0165 MPa) and the aqueous humor (0.00114 MPa). When using a plunger with a larger diameter to remove a RGP lens, although a larger force required, the relatively larger contact area likely reduced the stress on the cornea and aqueous humor, thereby reducing the risk of eye injury. In addition, when removing a RGP lens, the results of this study recommended it to be removed from the plunger edge, as that facilitated the removal of contact lens.

Corneal Transplantation in a Patient With Nonperforating Ocular Contusion Caused by a High-Pressure Washer: A Case Report

Purpose: This report details a rare case of a high-pressure washer injury that caused ocular contusion, vitreous hemorrhage, and irreversible corneal edema without perforation necessitating corneal transplantation. Methods: The medical chart of a patient with a high-pressure washer injury at Miyata Eye Hospital (Miyazaki, Japan) was retrospectively reviewed. Results: A 57-year-old man presented to our hospital with a contusion in the left eye caused by a high-pressure washer 1 day prior to the visit. The visual acuity in the left eye was hand motion. Slit-lamp examination of the left eye revealed the presence of corneal epithelial defects, conjunctival lacerations, hyphema, and lacerated iris. Mild clouding of the lens was observed in the anterior chambers, suggestive of cataract. Anterior segment optical coherence tomography revealed the presence of blood in the anterior chamber and a thickened and edematous cornea. Ultrasound examination revealed the presence of vitreous hemorrhage. Therefore, vitreous surgery and traumatic cataract removal were performed under general anesthesia. Postoperatively, the corneal edema and marked opacity persisted, accompanied by glaucoma, and the visual acuity was measured at 0.01. Penetrating keratoplasty was performed 1 year and 2 months after the injury, and scleral fixation of the intraocular lens was performed under local anesthesia 2 years after the injury. The final visual acuity was 0.1 under rigid gas-permeable contact lens usage 3.5 years after sustaining the injury, and the patient required anti-glaucoma drugs. Conclusions: Our patient presented with ocular trauma caused by a high-pressure washer. Corneal transplantation was required although no ocular lacerations were detected. Sufficient instructions must be provided on the usage of heavy machinery to develop a safe working environment.

What Happens 20 to 30 years After Radial Keratotomy? Case Series.

Radial keratotomy (RK) was commonly performed in the 1980s and 1990s. We aimed to clarify the current status of post-RK refractive correction and treatment. We retrospectively reviewed the charts of 70 patients with a history of RK. Of the 70 patients, 44 were identified for clinical outcomes. Refractive or therapeutic intervention (rigid gas-permeable contact lens fit, spectacle prescription, corneal surgery, and use of pilocarpine hydrochloride for photophobia) was possible in 59% of patients with postoperative visual deterioration after RK; in the remaining 41%, therapeutic intervention was not possible. Rigid gas-permeable contact lens fit for corneal irregular astigmatism was the most common refractive intervention and was effective in 36% of cases in the university hospital.

Slowing myopia progression in children

Background: A large proportion of individuals develop myopia, which is recognized as a global health concern and is predicted to increase in prevalence. Long-term eye problems are associated with myopia, particularly in young individuals. Retinal detachment and choroidal degeneration are among the causes of visual impairments associated with myopia. In this narrative review, we summarized the current measures for slowing myopia progression in children, including their safety profiles and potential drawbacks. Methods: We conducted an English literature search for articles published between January 1, 2000, and October 31, 2023, using various combinations of keywords related to myopia, myopia progression, childhood myopia, myopia control, atropine, orthokeratology, and contact lenses. We included original or review articles pertaining to lifestyle changes and pharmacological, optical, or laser interventions for managing myopia progression in children. Our search was conducted using PubMed/MEDLINE, Google Scholar, and the Wiley Online Library. We reviewed the full text of included articles and qualitatively summarized the results of relevant studies using a narrative synthesis approach. Results: Multiple meta-analyses indicated that increased outdoor time is associated with a lower myopia prevalence, with each extra hour spent outside each week reducing the risk of myopia by 2%. Candidate drugs, such as atropine, pirenzepine, and 7-methylxanthine, and certain intraocular pressure-lowering medications, such as timolol, have been studied in human trials for their ability to manage myopia. The nonselective antimuscarinic drug atropine, followed by the M1-selective antimuscarinic drug pirenzepine, displayed positive results in slowing myopia. Oral 7-methylxanthine, a nonselective adenosine receptor antagonist, reduces axial myopia caused by hyperopic defocus in a primate model. Low-intensity laser therapy using low doses of red and near-infrared light, visual biofeedback training, bifocal or multifocal spectacles, orthokeratology using a rigid gas-permeable contact lens, combined orthokeratology and atropine, soft contact lenses with a central distance zone and higher positive power in the periphery, and peripheral defocus contact lenses are among the interventional therapies with promising results in managing myopia progression in children. Conclusions: The current literature supports the efficacy of increased outdoor time, administration of pharmacological agents, and special contact lenses as treatment modalities for slowing myopia progression in children. The effectiveness of orthokeratology alone and in combination with topical atropine therapy has also been assessed. Further research is needed to pinpoint the precise mechanisms of action of these therapies and to determine the best course of treatment. The increasing global prevalence of childhood myopia necessitates robust interventional studies into slowing myopia progression and preventing high myopia and related sight-threatening conditions in adulthood.

Physiological Changes in the Cornea When Wearing Rigid Gas Permeable Contact Lenses

Rigid gas permeable (RGP) contact lenses are made of materials with excellent oxygen permeability and wettability, so they not only improve oxygen permeability compared to existing lenses, but also provide correction of refractive errors and improved vision in irregular corneas such as keratoconus. However, the hard material of the lens along with hypoxia and hypercapnia of the cornea caused by wearing RGP contact lenses cause various physiological changes in the cornea. Physiological changes in the cornea that may occur when wearing RGP contact lenses include mucin balls, decreased corneal epithelial thickness and increased size, decreased epithelial barrier function, corneal erosion and staining, decreased keratocyte density, decreased corneal sensitivity, and stromal opacities, contact lens‐induced peripheral ulcers, endothelial blebs, increased endothelial polymegethism, and changes in corneal shape. It is necessary to know the performance of the RGP contact lenses being prescribed, be aware of the physiological changes in the cornea caused by wearing RGP contact lenses, and provide the correct lens prescription along with appropriate education to the patient.

Rigid Gas Permeable (RGP) as Keratoconus Management After Corneal Collagen Cross-Linking (CXL) Procedure: a Case Report

Introduction : Rigid Gas Permeable (RGP) contact lenses are the mainstay for keratoconus patients and widely used. This case report presents RGP as a management for keratoconus after Corneal Collagen Cross- Linking (CXL) procedure.&#x0D; Case Illustration : A 22-year-old woman diagnosed with keratoconus since eight months ago, came for vision correction. She had CXL performed on both eyes. Ophthalmologic examination revealed uncorrected visual acuity of 0.63 in the right eye (RE) and 0.08 in the left eye (LE). Her best-corrected visual acuity (BCVA) was 1.0 in the RE with -0.75 D and 0.125 in the LE with -2.00 D. Anterior segment examination of the RE was unremarkable, but the LE has Vogt’s striae and Munson's sign (Figure 1). Corneal topography for the LE showed K1 64.7D/5.2 mm, K2 68.7D/4.9 mm, and Kmean 66.7D/5.1 mm. She was fitted with trial lens of BC 5.40 and the fit was loose. She then fitted with a BC of 5.50 mm showed a good fit result. RGP contact lenses were prescribed with S -8.50, BC 5.50, and 8.6 mm diameter for her LE and combined with spectacle for her RE. Her over-refraction BCVA of the LE was 0.9.&#x0D; Discussion : The management goals are to improve the patient’s visual acuity and to decrease the progression. The visual acuity of this patient improved after RGP fitting.&#x0D; Conclusion : The combination of CXL procedure and the use of RGP effective to increase visual acuity, regularity of corneal surface, and patient satisfaction. Keratoconus should be monitored regularly to avoid possible progressivity.

CAN RIGID GAS PERMEABLE (RGP) CONTACT LENS BE THE BEST OPTION FOR A KERATOCONUS PATIENT?

Introduction : Keratoconus is a condition of cone-shaped cornea caused by stromal thinning. This disorder leads to visual disturbance due to irregular astigmatism, myopia, and corneal protrusion. A severe irregular astigmatism must be corrected by rigid gas permeable (RGP) contact lenses.&#x0D; Case Illustration : A 29 y.o female visited Ophthalmologist Clinic Subdivision of Refraction, Contact Lens, and Low Vision in RSKMM Provinsi Sumsel, complaining of discomfort while using her current glasses. Anamnesis, physical examination, and ophthalmologic examination were carried out. The patient then was maximally corrected of her refractive status, followed by contact lenses fitting and post- fitting evaluation.&#x0D; Discussion : Early ophthalmologic examination showed visual acuity of 6/60 ph 6/9 on both eyes. Corneal topography evaluation confirmed pattern of bilateral keratoconus, each 78% on right eye and 87% of left eye. Best-corrected visual acuity was 6/6 using S-3.50 C-7.00 180? (right eye) and S-4.00 C-6.00 170? (left eye). RGP fitting test was carried with trial lenses of S-4.00 D for both eyes with both base curve of 7.2 mm and diameter of 9.2 mm. Over-refraction showed result of S-3.50 D (right eye) and S-3.75 D (left eye) for both eyes to reach visual acuity of 6/6 and for patient to feel comfortable.&#x0D; Conclusion : While some period of adaptation was needed, severe keratoconus should be treated using RGP contact lenses to achieve a better prognosis. Accurate fitting test of RGP resulting in comfortable and satisfied outcome of patient.

The Comparison of Visual Acuity between Spectacles and Rigid Gas Permeable (RGP) Group in Myopia Patients

Introduction &amp; Objectives : The prevalence of myopia has approximately doubled in the past three decades, with rates of 70–87% among populations of school children and young adults in Asia. Approaches to treating myopia include spectacles and Rigid Gas Permeable (RGP) contact lenses. RGP has become a new "preference" because it is more comfortable and provides a more aesthetic look. This study aims to determine which method is better for correcting visual acuity in myopia patients.&#x0D; Methods : This cross-sectional study analyzed the outcomes and exposures measured at the same time. The sample included myopia patients (based on spherical equivalent) who underwent RGP contact lens fitting in the refraction outpatient clinic of M Djamil Hospital from January 2021 to December 2022. The samples were selected based on inclusion and exclusion criteria. The collected data included gender, age, and best-corrected visual acuity using spectacles and RGP.&#x0D; Results : Forty-three patients were eligible as the sample in this study. Most of the subjects were women (62.8%), and the mean age was 23.58 years old. The median LogMAR for the RGP group was lower than the spectacles group (0.00:0.10 on both eyes). Statistical analyses found a significant visual acuity improvement in the RGP group compared to the spectacles group in both the right and left eyes (p = 0.014 and p = 0.005, respectively (p &lt; 0.05)).&#x0D; Conclusion : The use of RGP provides significantly better visual acuity in correcting myopia than spectacles. Myopia is more frequently found in young women.

THE COMPARISON BEST CORRECTION VISUAL ACQUITY (BCVA) BETWEEN SPECTACLES AND SPHERICAL RIGID GAS PERMEABLE (RGP) IN HIGH ASTIGMATISM PATIENTS

Introduction &amp; Objective : Rigid Gas Permeable (RGP) toric contact lenses are generally considered in patients with high astigmatism, while spherical RGP contact lenses are present as an alternative option that can be used and still provide optimal results in patients with high astigmatism.&#x0D; Methods : A cross-sectional study was conducted at DR M Djamil Hospital Padang in January 2021 to December 2022 period. Inclusion criteria were patients who went to the eye clinic at DR M. Djamil Hospital in January 2021 to December 2022 period, patients with high astigmatism ? -2.00 D underwent correction vision with spectacles and RGP spherical contact lenses. Results best correction visual acquity (BCVA) compared between spectacles and spherical RGP contact lenses. Samples must meet the inclusion and exclusion criteria. Data is collected and analyzed using statistical applications.&#x0D; Results : 49 patients with high astigmatism corrected with spectacles and contact lenses showed data distribution was 15 men (30.6%) and 34 women (69.4%). Most age in the age group 20-29 years 24 people (49%). BCVA with spectacles obtained a median of 0.18 and an RGP of 0.00 based on LogMar. Mann whitney test showed significant difference between BCVA wearing glasses and RGP spherical contact lenses with a value of p = 0.006 right eye p = 0.009 left eye (p &lt;0.005)&#x0D; Conclusion : Spherical RGP contact lenses can still be used in patients with high astigmatism if we don’t have toric RGP trial. Spherical RGP contact lenses show better BCVA results than spectacles in high astigmatism patients.

Barriers to the Diagnosis and Management of Keratoconus Among Optometrists in Kenya.

Early diagnosis and management of keratoconus (KC) are important for limiting visual complications of the disease. This study aimed to explore the perspectives of optometrists on the barriers to effective diagnosis and management of KC in Kenya. An online questionnaire was distributed to optometrists in Kenya to collect data on barriers to the diagnosis and management of KC. The majority (60.9%) of optometrists were confident in retinoscopy and subjective refraction. Fewer were confident in the use of keratometers (46.4%) and corneal topographers (24.9%) and in the fitting of rigid gas permeable (RGP) contact lenses (25.0%). The most commonly reported barriers to improving their knowledge and skills were, limited continuous professional development opportunities (87.4%), high costs of conferences (86.1%) and the lack of diagnostic tools (79.5%). Impediments cited to diagnosing and managing KC effectively were a lack of national guidelines (64.9%), patient education material (71.5%), equipment (58.9%) and RGP supply (68.2%) and cost (67.5%). Most commonly reported barriers related to patients were compliance (91.4%), affordability (90.7%), RGP discomfort (89.4%), willingness to pay (88.1%) and the lack of patient education about KC (87.4%). This study showed that the lack of national guidelines, essential equipment and adequate practitioner knowledge and skills were barriers to KC diagnosis and management. Regulation of optometric education and clinical practice, development of national guidelines for diagnosis and management of KC, up-skilling of practitioners and cost-effective solutions for equipment procurement and maintenance may improve both access to, and quality of, care to patients with KC.

Using clinical optical coherence tomography to characterise contact lens edge shape and base curve radius

ABSTRACT Clinical relevance Clinical optical coherence tomography devices are widely used in optometry and ophthalmology and may be used to measure contact lens base curvature radius and visualise contact lens edge shape. Background Knowledge of contact lens geometry facilitates fitting, while optical coherence tomography provides a powerful means of measuring geometrical form. This study evaluates the performance of a clinical optical coherence tomography device (3D OCT-1000) in characterising contact lens edge shape and measuring the back optic zone radius of rigid gas-permeable contact lenses in vitro. Methods First, an opto-mechanical optical coherence tomography contact lens adaptor was designed and 3D-printed to facilitate a contact lens being imaged using a commercial optical coherence tomography device. Second, several image-processing algorithms and a simple calibration method were developed to measure the back optic zone radius in optical coherence tomography B-scans. Finally, based on the findings of two experiments, B-scan performance was evaluated in terms of 1) capacity to differentiate between contact lens edge geometries, and 2) capacity to obtain accurate and repeatable back optic zone radius measurements. Statistical and graphical analyses were performed to characterise reliability and reproducibility. Results The 3D OCT-1000 and adaptor combination was capable of acquiring images of sufficient quality to discriminate between soft and rigid contact lens edge geometries. Additionally, statistical analysis of the rigid contact lens measurements demonstrated satisfactory back optic zone radius measurement accuracy and reproducibility. Conclusion This study demonstrates that a 3D OCT-1000 fitted with an opto-mechanical adaptor combination can be used to assess contact lens edges in vitro and that this clinical optical coherence tomography device, combined with image processing and linear calibration of the B-scans, is capable of obtaining back optic zone radius measurements of rigid gas-permeable contact lenses that are close to the ISO 18,369-2:2018 manufacturing tolerance range (±0.05 mm).

Effect of sodium hyaluronate eye drop on tear film stability and tear secretion in patients with rigid gas permeable contact lens associated xerophthalmia

Purpose: To evaluate the impact of sodium hyaluronate eye drops on tear film stability and tear secretion in patients suffering from rigid gas-permeable contact lenses (RGPCL)-associated xerophthalmia.&#x0D; Methods: 88 patients treated at Shangrao Aier Eye Hospital, China with RGPCL-associated xerophthalmia were enrolled in this study from May 2021 to May 2022. They were randomly and equally divided into two groups: a study group (treated with sodium hyaluronate eye drops) and a control group (treated with meibomian gland massage). Tear secretion parameters (lacrimal river width, Schirmer I test (S1t), tear fluid lysozyme content), tear film stability indicators (tear film break-up time, tear film thickness, corneal fluorescein staining score), ocular surface disease index (OSDI), therapeutic effect and incidence of adverse reactions were compared between the two groups.&#x0D; Results: Following the treatment, study group exhibited significantly improved tear secretion compared to control group (p &lt; 0.05). Similarly, tear film stability indicators significantly improved in study group after treatment, accompanied by a reduction in corneal fluorescein staining score (p &lt; 0.05). Although both groups showed decreased OSDI scores after treatment, the reduction was more substantial in study group. Additionally, the therapeutic effect and incidence of adverse reactions were superior in study group compared to control group.&#x0D; Conclusion: The use of sodium hyaluronate eye drops in the treatment of patients with RGPCL-associated xerophthalmia enhances tear secretion, and improves tear film stability and therapeutic outcomes, leading to a reduction in ocular surface disease index and the incidence of adverse reactions. However, this treatment strategy warrants a large-scale clinical trial prior to application in clinical practice.