Clinical evaluation of different types of contact lenses in keratoconus management

Visual rehabilitation using rigid gas permeable contact lenses after femtosecond laser-assisted minimally invasive lamellar keratoplasty in patients with keratoconus

This study aims to observe the clinical efficacy and safety of rigid gas permeable corneal contact lenses (RGP-CLs) wearing after femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) in progressive and advanced keratoconus eyes. Twenty-five patients (27 eyes) fitted with RGP-CLs after FL-MILK were enrolled, and 22 grading-matched keratoconus patients (23 eyes) as a control group. Corneal morphological data, diopter, best corrected vision, corneal endothelium, non-invasive tear film rupture time (NIBUT), corneal perception and comfort questionnaire were analysed before and after wearing RGP-CLs. In the FL-MILK group, the flat K, steep K and Kmax of the corneal anterior surface were decreased by 3.05D, 3.48D and 7.17D respectively after surgery (P = 0.011, 0.004 and 0.007). The central corneal thickness increased by 175.29 μm (P < 0.001). The basic curve of RGP-CLs after surgery was about 0.23 mm flatter than that before surgery (P = 0.013). There was no statistical difference in the best corrected vision and the comfort of wearing RGP-CLs before and after FL-MILK (P = 0.923, 0.391). Compared with the control group, there was no significant difference in vision improvement by RGP-CLs (P = 0.669). During the follow-up, the comfort of wearing RGP-CLs in the two groups was good, and no obvious adverse events were observed. This study showed MILK significantly increases corneal thickness and flattens corneal curvature, achieving good RGP-CLs corrected vision.

Binocular vision parameters and visual performance in bilateral keratoconus corrected with spectacles versus rigid gas-permeable contact lenses

PURPOSE

To analyze binocular vision of individuals aged 18 to 35 years diagnosed with keratoconus, utilizing spectacles and rigid gas-permeable (RGP) contact lenses. Research was led by the Universidad Autónoma de Aguascalientes, México and Fundación Universitaria del Área Andina Pereira, Colombia.

METHODS

A single center, prospective non-randomized, comparative, interventional, open-label study, in which the differences in binocular vision performance with both spectacles and RGP contact lenses was carried out from December 2018 to December 2019. Sampling was performed according to consecutive cases with keratoconus that met the inclusion criteria until the proposed sample size was reached.

RESULTS

Rigid gas-permeable (RGP) contact lenses notably enhanced distance and near visual acuity in keratoconus patients compared to spectacles. Visual alignment analysis shows exophoria at both distances and is slightly higher with RGP contact lenses. The difference was statistically significant (p<0.05), with 82.5 % presenting compensated phoria with spectacles and pnly 42.50% with RGP contact lenses. Stereoscopic vision improved while wearing RGP contact lenses (42.59 %), although accommodation and accommodative flexibility remained within normal ranges.

CONCLUSIONS

Patients with keratoconus fitted with RGP contact lenses have improved binocular vision skills such as visual acuity, stereopsis, and accommodative flexibility. However, even when the vergence and motor system is decompensated with respect to normal ranges, the range between break and recovery points for both fusional reserves and the near point of convergence (NPC) improves with the use of RGP contact lenses, giving indications of an adaptive condition of the motor system from the medium to the long term.

Less Complex Contact Lens Required for a Patient With Keratoconus After Topography-Guided Photorefractive Keratectomy

ABSTRACT

In this report, we discuss contact lens (CL) fitting in a patient with a history of keratoconus (KC), before and after undergoing topography-guided photorefractive keratectomy (TG PRK). Before TG PRK, the patient failed multiple CL modalities and reported difficulty with his habitual CLs and inadequate spectacle-corrected visual acuity to perform his activities of daily living. In this case, a collaborative, comprehensive approach to visual management in a patient with KC was used, and after TG PRK was performed to improve his corneal contour and symmetry, our patient was fit with a standard soft CL and additionally had improved spectacle-corrected visual acuity.

Prevalence and clinical profile of keratoconus in patients presenting at a provincial hospital in KwaZulu, Natal, South Africa: A case study

Keratoconus (KC) is a progressive, asymmetrical corneal disease, characterized by stromal thinning that leads to distortion, causing vision loss. The visual loss is secondary to corneal scarring, irregular astigmatism, and myopia. The prevalence of KC has been reported to differ in different parts of the world. The study aimed to determine the prevalence and profile of patients with KC presenting to a provincial hospital in KwaZulu-Natal, South Africa. A retrospective study design was used to review 412 clinical records of patients attending the McCord Provincial Eye Hospital (MPEH) during a five-year period (2016-2020). Data on age, race, refraction, clinical profile, treatment plan, and diagnosis were ascertained. The prevalence of KC in MPEH was found to be 13.7% with a mean age of 24.7±7.94 years. Black African and females had a higher frequency of KC compared to males and other ethnic groups. Most of the patients presented with a severe stage of KC and referral was the most common management. Central corneal thinning and Munson's sign were the most prevalent clinical signs. There was no statistically significant difference between the worse and better eye when comparing the clinical signs. The prevalence and clinical profile of patients with KC in this study was similar to that reported by previous studies and more in Blacks and females. Population based epidemiological studies are needed to determine the prevalence of KC in South Africa to enable early clinical interventions.

Evidence of Contact Lenses for Vision Rehabilitation in Corneal Diseases: A Review

OBJECTIVES

To evaluate the efficacy and safety of contact lenses (CL) as a therapeutic option for patients affected by a corneal disease and to determinate which is the best lens modality for each disease.

METHODS

A literature review using PubMed was performed. All relevant articles published during the last 15 years have been included.

RESULTS

Various studies point to CL as the best therapeutic option for some corneal diseases and even as an alternative to surgery in some cases. After fitting, patients show an improvement in their functional vision and quality of life, in some cases being able to drive or work again.

CONCLUSIONS

There is a lack of scientific evidence to determine which lens modality is suitable for each corneal pathology. Currently, according to this review, the reason for choosing between the different options depends on the severity of symptoms, and it is worth mentioning that scleral lenses seem to be the best option in advanced stages of disease. However, the expertise of professionals is also an important factor at the time of choosing a particular CL modality. Standardized criteria are still necessary for correct selection of lens modality for a correct management of the disease.

Management of keratoconus: an updated review

Keratoconus is the most common corneal ectatic disorder. It is characterized by progressive corneal thinning with resultant irregular astigmatism and myopia. Its prevalence has been estimated at 1:375 to 1:2,000 people globally, with a considerably higher rate in the younger populations. Over the past two decades, there was a paradigm shift in the management of keratoconus. The treatment has expanded significantly from conservative management (e.g., spectacles and contact lenses wear) and penetrating keratoplasty to many other therapeutic and refractive modalities, including corneal cross-linking (with various protocols/techniques), combined CXL-keratorefractive surgeries, intracorneal ring segments, anterior lamellar keratoplasty, and more recently, Bowman's layer transplantation, stromal keratophakia, and stromal regeneration. Several recent large genome-wide association studies (GWAS) have identified important genetic mutations relevant to keratoconus, facilitating the development of potential gene therapy targeting keratoconus and halting the disease progression. In addition, attempts have been made to leverage the power of artificial intelligence-assisted algorithms in enabling earlier detection and progression prediction in keratoconus. In this review, we provide a comprehensive overview of the current and emerging treatment of keratoconus and propose a treatment algorithm for systematically guiding the management of this common clinical entity.

Multifunctional glycoprotein coatings improve the surface properties of highly oxygen permeable contact lenses

To achieve and maintain good operability of medical devices while reducing putative side effects for the patient, a promising strategy is to tailor the surface properties of such devices as they critically dictate the tissue compatibility and the biofouling behavior. Indeed, those properties can be strongly improved by generating mucin coatings on such medical devices. However, using coatings on optical systems, e.g., contact lenses, comes with various challenges: here, the geometrical and optical characteristics of the lens may not be compromised by either the coating process or the coating itself. In this study, we show how mucin macromolecules can be attached onto the surfaces of rigid, gas permeable contact lenses while maintaining all critical lens parameters. We demonstrate that the generated coatings improve the surface wettability (contact angles are reduced from 105° to 40° and liquid film break-up times are increased from <1 s to 31 s) and prevent tribological damage to corneal tissue. Additionally, such coatings are highly transparent (transmission values above 98 % compared to an uncoated sample are reached) and efficiently reduce lipid deposition to the lens surface by 90 % but fully maintain the geometrical and mechanical properties of the lenses. Thus, such mucin coatings could also be highly beneficial for other optical systems that are used in direct contact with tissues or body fluids.

Correction of moderate to high refractive astigmatism with extended range toric soft contact lenses in patients with different patterns of astigmatism

PURPOSE

This study aimed to evaluate the visual performance of extended range, toric soft contact lenses (TSCLs) in patients with keratoconus and moderate to high astigmatism with different astigmatic patterns.

METHODS

This was a retrospective, cross-sectional clinical study. Extended range TSCL users with astigmatism ≥3.0 D were included. Cases were categorised into three subgroups, namely regular, irregular (non-keratoconus) and keratoconic based on the topographic pattern of astigmatism. In addition, subjects were subdivided based on the degree of astigmatism.

RESULTS

Fifty five patients (82 eyes) were enrolled, of whom 28 (51%) were female. The mean age was 24.2 ± 7.5 (range: 8-41 years) years. Thirty-six eyes with regular astigmatism (43.9%), 34 eyes with irregular astigmatism (41.5%) and 12 eyes with keratoconus (14.6%) were included. The percentage improvement in visual acuity (VA) was significantly higher with contact lenses compared with spectacles in all groups (p < 0.001), with the highest improvement in subjects with keratoconus (p = 0.03). Twenty six (31.7%), 30 (36.6%) and 26 eyes (31.7%) had moderate (-3.0 to -4.24 D), moderate/high (-4.25 to -5.99 D) and high (≤-6.0 D) astigmatism, respectively. The percentage improvement in VA with contact lenses was statistically significantly higher than for spectacle wear in all groups (p < 0.001).

CONCLUSIONS

This study demonstrated that satisfactory visual outcomes can be obtained with extended range TSCLs in patients having moderate to high astigmatism with different astigmatic patterns.

Keratoconus: An updated review

Keratoconus is a bilateral and asymmetric disease which results in progressive thinning and steeping of the cornea leading to irregular astigmatism and decreased visual acuity. Traditionally, the condition has been described as a noninflammatory disease; however, more recently it has been associated with ocular inflammation. Keratoconus normally develops in the second and third decades of life and progresses until the fourth decade. The condition affects all ethnicities and both sexes. The prevalence and incidence rates of keratoconus have been estimated to be between 0.2 and 4,790 per 100,000 persons and 1.5 and 25 cases per 100,000 persons/year, respectively, with highest rates typically occurring in 20- to 30-year-olds and Middle Eastern and Asian ethnicities. Progressive stromal thinning, rupture of the anterior limiting membrane, and subsequent ectasia of the central/paracentral cornea are the most commonly observed histopathological findings. A family history of keratoconus, eye rubbing, eczema, asthma, and allergy are risk factors for developing keratoconus. Detecting keratoconus in its earliest stages remains a challenge. Corneal topography is the primary diagnostic tool for keratoconus detection. In incipient cases, however, the use of a single parameter to diagnose keratoconus is insufficient, and in addition to corneal topography, corneal pachymetry and higher order aberration data are now commonly used. Keratoconus severity and progression may be classified based on morphological features and disease evolution, ocular signs, and index-based systems. Keratoconus treatment varies depending on disease severity and progression. Mild cases are typically treated with spectacles, moderate cases with contact lenses, while severe cases that cannot be managed with scleral contact lenses may require corneal surgery. Mild to moderate cases of progressive keratoconus may also be treated surgically, most commonly with corneal cross-linking. This article provides an updated review on the definition, epidemiology, histopathology, aetiology and pathogenesis, clinical features, detection, classification, and management and treatment strategies for keratoconus.

Comparison of Keratoconus Cone Location of Different Topo/tomographical Parameters

Purpose: To compare the corneal cone location on different maps and instruments, and their agreements, with elevation maps.Methods: In 90 left eyes with bilateral keratoconus, the apex of cone location was determined based on the maximum simulated keratometry (Kmax) location on the anterior sagittal curvature map by Pentacam HR, the maximum curvature on the mean curvature map by ATLAS 9000, most elevated point of the island of positive elevation relative to the best fit sphere on the front and back corneal elevation maps by Pentacam HR, and thinnest point on the thickness map by Pentacam HR and Orbscan, and the thinnest points on pachymetry and epithelial thickness maps by RTVue OCT.Results: There was a significant difference among the location on different maps along the x- and y-axes (p < .001). The lowest agreement with the cone apex on both front and back elevation maps was for the anterior sagittal curvature map and the highest agreement for the Pentacam thickness map. The majority of keratoconus cone apexes were displaced in the inferotemporal direction on the different maps except for the epithelial thickness maps.Conclusions: Despite the variability between different devices and methods; the thickness map on the Pentacam HR showed the highest correlation with the front and back elevation maps, while the RTVue epithelial thickness map showed the poorest correlation. Based on this study, epithelial thickness maps and anterior curvature maps should be utilized with caution to determine the location of the cone.

Two-Year Follow-up of Intracorneal Ring Segments Implantation in Adolescent Patients With Keratoconus

PURPOSE

To evaluate the visual, refractive, topographic, and aberrometric outcomes after intracorneal ring segments (ICRS) implantation in adolescent patients with keratoconus.

METHODS

A retrospective longitudinal study was undertaken with a total of 61 eyes from 47 patients with keratoconus, aged between 13 and 18 years, implanted with a Ferrara-type ICRS. Topography (flattest keratometry, steepest keratometry, and asphericity), uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive error (sphere and cylinder), and aberrometric measurements (spherical aberration and vertical coma) were evaluated before surgery and at 1 month, 6 months, 1 year, and 2 years after surgery.

RESULTS

UDVA exhibited a statistically significant increase at all times from 1 month to 2 years postoperatively (P < .001), whereas CDVA showed a statistically significant improvement at 1 month, 6 months, and 2 years (P < .002), but dropped in significance at 1 year postoperatively (P = .097). The refractive error analysis showed no variation in statistical significance in the sphere (P = .712) after 2 years. The cylinder presented a statistically significant decrease in diopters at all times from preoperatively to 2 years postoperatively (P < .007). Steepest keratometry manifested a statistically significant decrease in steepness at all times after surgery (P < .001), whereas flattest keratometry lost significance at 1 year (P = .298) and 2 years (P = .053) postoperatively. There was no statistically significant change in the spherical aberration at any of the measured times. The vertical coma was only significantly different at 2 years postoperatively (P = .001).

CONCLUSIONS

ICRS implantation is a safe and effective treatment for improving visual and corneal morphological parameters as shown at 2 years of follow-up in adolescent patients with keratoconus. It is a good option to flatten and regularize the cornea and to temporarily improve the quality of life of young patients and delay the need for keratoplasty. [J Refract Surg. 2021;37(2):91-97.].

Safety and Efficacy of Corneal Minimized-Volume Ablation With Accelerated Cross-Linking in Improving Visual Function for Keratoconus

PURPOSE

To evaluate the safety and efficacy of corneal minimized-volume ablation with accelerated cross-linking in improving visual function in keratoconus eyes.

METHODS

Through a pilot study, 25 eyes of 25 consecutive patients with keratoconus grade I-III were recruited that underwent corneal transepithelial photorefractive keratectomy with "minimized volume" ablation profile and accelerated corneal cross-linking in the same session. Corrected and uncorrected distance visual acuities, manifest refraction, corneal curvature and higher-order aberrations, endothelial cells, and the ocular modulation transfer function were assessed preoperatively and postoperatively, with a minimum follow-up of 6 months. A P value < 0.05 was the threshold of statistical significance.

RESULTS

At 8.2 ± 3.6 months postoperatively, the mean corrected and uncorrected distance visual acuities (LogMAR) were 0.07 ± 0.15 and 0.45 ± 0.39, significantly improving from the baseline of 0.24 ± 0.24 (P8m-before = 0.005) and 1.12 ± 0.33 (P8m-before < 0.001), respectively. Spherical equivalent was -2.80 ± 2.72 diopters (D), significantly decreasing from the baseline of -6.61 ± 3.06 D (P8m-before < 0.001), whereas the attempted corrected spherical equivalent was-2.30 ± 1.22 D. Meanwhile, a significant reduction was found in higher-order aberration, along with the postoperative improvement in ocular modulation transfer function. Corneal surface morphological parameters were found with significant decreases postoperatively (index of surface variance: P8m-before = 0.003; index of vertical asymmetry: P8m-before = 0.005; keratoconus index: P8m-before = 0.004; center keratoconus index: P8m-before = 0.003; and index of height decentration: P8m-before < 0.001). Nevertheless, no significant change was found in posterior corneal curvature or endothelial cell density between pre- and post-operative periods.

CONCLUSIONS

Corneal minimized-volume ablation with accelerated cross-linking was an effective and safe option for correction of mild refractive error, leading to significant improvement of visual function in patients with keratoconus.

Improved contact lens fitting after corneal cross-linking in eyes with progressive keratoconus

OBJECTIVES

The study aimed to assess the possible effects of corneal cross-linking (CXL) on contact lens (CL) fitting in patients with progressive keratoconus who initially had CL intolerance.

METHODS

A retrospective review was performed of the medical records of patients who had stopped CL wear due to discomfort prior to CXL and who were fitted with CLs after CXL. All eyes were evaluated pre- and 1, 6, 12, 24 months postoperatively. Data collected included pre- and post-CXL refraction, corneal topographic data, uncorrected visual acuity, and best-corrected visual acuity (BCVA). CL comfort was evaluatedusing theLikert scale post-CXL.

RESULTS

A total of 20 eyes from 14 patients were included in the study. Preoperative Kmax values significantly decreased by 2.8 D at 6 months and by 4.1 D at 12 months after CXL (p < 0.001 for both). CLs were prescribed on average 12 ± 2.5 months after CXL. The mean duration of successful CL wear was 10.4 ± 2.8 months during the follow-up period. Subjective CL comfort scores were satisfactory post-CXL.

CONCLUSION

CXL not only halts the progression of keratoconus but may also improve CL tolerance by providing a more regular shaped cornea in these patients. Ongoing corneal topographic changes in the late postoperative period after CXL may have a positive effect on CL fitting.

Clinical Outcome of Hybrid Contact Lenses in Keratoconus

OBJECTIVES

To report the clinical outcome of hybrid contact lens fitting in keratoconus.

METHODS

A retrospective chart review was performed of keratoconus patients who had been fitted with hybrid contact lenses in one or both eyes. Patients with a history of previous intraocular surgery (except for corneal crosslinking) and relevant concurrent ocular disease limiting visual outcome were excluded. The outcome data at 6-month follow-up included hybrid lens-corrected visual acuity, wearing time, and lens discontinuation.

RESULTS

Fifty-four keratoconus patients (102 eyes) were included. Mean visual acuity with habitual correction before hybrid lens fitting was 0.63±0.29 (decimal Snellen). Eyes were fitted with Eyebrid lenses (LCS Laboratories, Caen, France) and SynergEyes lenses (SynergEyes Inc., Carlsbad, CA). Refits were necessary in 13 eyes, because of poor fitting (76.9%) or suboptimal refraction (23.1%). Visual acuity had significantly improved with hybrid lenses (0.93±0.14; P<0.0001). In 37 eyes (37.8%), hybrid lens wear was discontinued within 6 months after lens fitting. Reported issues were discomfort in 27 eyes (73%), handling difficulties in 14 eyes (37.8%) and poor vision in 1 eye (2.7%). Success rate of lens fitting was significantly correlated to cone morphology (P=0.01).

CONCLUSIONS

New generation hybrid lenses are an appropriate, safe therapeutic option for keratoconus patients. Excellent visual outcomes are achieved in successful fittings, yet a dropout rate of 37.8%-mainly occurring in sagging, more peripheral, cones - still limit their clinical success.

CLEAR - Medical use of contact lenses

The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.

Lamellar Keratoplasty for Advanced Keratoconus

Ectatic corneal diseases are a group of disorders resulting in progressive corneal steepening and thinning. Keratoconus, keratoglobus, pellucid marginal degeneration, post-keratorefractive ectasia, and corneal graft ectasia are the types of corneal ectasia. Early diagnosis with appropriate diagnostic tools can help prevent progression, eliminating the need for corneal transplantation. Lamellar or full thickness corneal transplantation are the treatment options for advanced diseases. Although the visual outcomes of penetrating keratoplasty are comparable to anterior lamellar keratoplasty (ALK) especially in keratoconus, ALK is the preferred treatment of choice considering benefits including reduced graft rejection, less long-term complications, and better graft survival. This article reviews the various surgical techniques in ALK with its clinical outcomes in advanced keratoconus.

Evaluation of Visual Acuity Outcomes and Corneal Alterations of New Generation Hybrid Contact Lenses in Patients With Advanced Keratoconus

PURPOSE

To evaluate the visual and corneal outcomes of new generation hybrid contact lenses (HCL) in patients with advanced keratoconus.

METHODS

This was a retrospective study undertaken at a single academic center. The study cohort consisted of subjects with advanced keratoconus who had elected not to undergo keratoplasty and were fitted with HCLs. Patients were fitted either with EyeBrid (LCS, Cane, France) or Airflex (SwissLens, Prilly, Switzerland) HCLs. Primary outcome measures included contact lens (CL) drop-out rate, best corrected visual acuity, and corneal endothelial cell density (ECD) measurements at the end of a 6-month HCL wear. ECD was measured using in vivo confocal microscopy (ConfoScan4; Nidek, Tokyo, Japan). One eye per patient was included for statistical purposes. Paired t tests and Wilcoxon signed-rank tests were used for comparative analyses.

RESULTS

Thirty-two keratoconic eyes of 32 patients (14M/18F) with a mean age of 25.9 ± 11.5 years were included in the study. All patients were able to continue CL wear for a duration of 6 months. There was a significant improvement in the mean best corrected visual acuity from 0.5 ± 0.2 logarithm of minimal angle of resolution to 0.1 ± 0.1 logarithm of minimal angle of resolution after daily CL wear with HCL at the 6-month follow-up visit (P < 0.001). No vision-threatening CL-related corneal adverse effects were observed. There was no significant reduction in the ECD noted at the 6-month visit [2625.8 ± 300.3 cells/mm (baseline) vs. 2566.4 ± 309.8 cells/mm (6-month); P = 0.623].

CONCLUSIONS

Hybrid contact lenses can provide improved visual function without inducing any short-term clinical or microscopic adverse effects on corneal endothelial cells in patients with advanced keratoconus.