A clinical and optical evaluation of a modified lens for irregular corneae

Use of new-generation hybrid contact lenses for managing challenging corneas

INTRODUCTION

To evaluate the safety and efficacy of new-generation hybrid contact lenses (HCL) among patients with irregular astigmatism.

METHODS

Medical records of 25 patients fit with new-generation HCL (Eyebrid^® and AirFlex^®) were retrospectively reviewed. The data collected included etiology of irregular astigmatism, uncorrected visual acuity, manifest refraction, spectacle-corrected visual acuity (S-CDVA), steep / flat keratometric values, corneal astigmatism, records of rigid / soft CL fitted before HCL, all parameters of the trial lenses, and the final prescribed HCL parameters and HCL-CDVA.

RESULTS

The study included 34 eyes from 25 patients (nine females and 16 males) with an average age of 29 ± 13 (ranging from 8-56) years. In total, 25 eyes with keratoconus, four with post - keratoplasty astigmatism, three with irregular astigmatism due to corneal trauma and two with residual astigmatism after radial keratotomy were fit with HCL. The mean S-CDVA (logMAR) improved significantly from 0.76 ± 0.41 to 0.14 ± 0.15 with HCL (p < 0.01). The most common indication for HCL was inability to fit with rigid gas permeable (RGP) lenses (22 eyes). The average number of lenses to successful fit was 1.4 (mode, 1; median, 1) and ideal fit was achieved with the first trial lens in 25 eyes (73%). Seven patients (nine eyes, 36%) discontinued lens use within the first 6 months because of discomfort (six eyes, 24%), ocular allergy (two eyes, 8%) and tearing of contact lens (one eye, 4%).

DISCUSSION

New-generation HCL may be a suitable option for fitting challenging corneas with irregular astigmatism that cannot be rehabilitated efficiently with rigid lenses.

Nonsurgical Procedures for Keratoconus Management

Objectives

To describe the past 20 years' correction modalities for keratoconus and their visual outcomes and possible complications.

Methods

A review of the published literature related to the visual outcomes and possible complications in the context of keratoconus management using nonsurgical procedures for the last 20 years (glasses and contact lenses) was performed. Original articles that reported the outcome of any correction modalities of keratoconus management were reviewed.

Results

The most nonsurgical procedure used on keratoconus management is the contact lens fitting. Soft contact lenses and soft toric contact lenses, rigid gas-permeable contact lenses, piggyback contact lens system, hybrid contact lenses, and scleral and corneoscleral contact lenses form the contemporary range of available lens types for keratoconus management with contact lenses. All of them try to restore the vision, improve the quality of life, and delay surgical procedures in patients with this disease. Complications are derived from the intolerance of using contact lens, and the use of each depends on keratoconus severity.

Conclusions

In the context of nonsurgical procedures, the use of contact lenses for the management of keratoconic patients represents a good alternative to restore vision and improve the quality of live in this population.

Improved Vision and Contact Lens Wear Time With Piggy-Back Contact Lens Systems in Children After Penetrating Corneal Trauma

OBJECTIVE

Consecutive case series of children treated successfully with "piggy-back" (PB) contact lens systems after corneal trauma.

METHODS

We reviewed the medical record of all children ages 4 to 14 years treated at the Emory Eye Center between January 11, 2003 and January 11, 2013 with PB contact lens systems.

RESULTS

Four children with a history of corneal penetrating trauma were treated with a PB lens system, with a mean age of 7±0.08 (range: 6-8) years. Best-corrected spectacle vision was count fingers in two children and logMAR +0.70 (Snellen equivalent 20/100) and logMAR +0.6 (Snellen equivalent 20/80) in the remaining two. The PB lens system was introduced with a mean of 15.7±6.5 (range: 9-22) months after the injury. All patients were initially fitted with gas-permeable (GP) lenses. Each child achieved 11 or more hours of daily contact lens wear time in PB systems. The mean best-corrected logMAR visual acuity using the PB system was 0.26±0.21 (Snellen equivalent 20/36). The mean improvement in best-corrected logMAR between GP and PB lens systems was +0.21±0.11, which corresponds to an improvement of greater than two lines on the Snellen chart.

CONCLUSION

Piggy-back contact lens systems can be helpful to improve vision and contact lens wearing time in children with irregular astigmatism after corneal trauma, who are intolerant of GP contact lenses.

Clinical evaluation of rigid gas permeable contact lenses and visual outcome after repaired corneal laceration

OBJECTIVE

To evaluate the clinical value of rigid gas permeable contact lenses (RGPCLs) in patients with traumatic corneal scarring and address implications of primary corneal repair.

METHODS

Eighteen subjects with a history of corneal laceration were fit with RGPCLs. Scar locations were divided into two zones; each patient was examined using Pentacam. Entering data included uncorrected visual acuity (UCVA), spectacle-corrected visual acuity (SVA), time between injury and RGPCL fitting, location and size of scar, and amount of corneal astigmatism. Follow-up data included RGPCL visual acuity (RGPCLVA), RGPCL-related complications, and dropout characteristics. Visual acuity values were converted to logMAR for analysis.

RESULTS

No serious complications occurred. The average time between suture removal and RGPCL fitting was 5.7±5.5 months. Average corneal astigmatism was -3.44±2.09 diopters. One subject had developed corneal ectasia. RGPCLVA was more than 0.1 in three subjects: one experienced primary corneal repair complications, and two subjects (<10 years) developed amblyopia. In both zones, the difference in RGPCLVA outcome between zone I and zone II was not statistically significant (F=0.060, P=0.809). The difference between SVA in zones I and II was found to be statistically significant (F=6.131, P=0.026), as were the differences between SVA and RGPCLVA (F=8.598, P=0.010). The scar size had no significant influence on RGPCLVA, SVA, or UCVA. Four participants (22.2%) were successfully fit. Dropout characteristics included ocular discomfort, inconvenience, parental apprehension, and low motivation.

CONCLUSIONS

Rigid gas permeable contact lens is an ideal method for evaluating visual potential in patients with traumatic corneal astigmatism. Pentacam examinations of those patients with poor RGPCLVA can help an ophthalmologist find and understand existing problems in suture techniques.

High Dk piggyback contact lens system for contact lens-intolerant keratoconus patients

BACKGROUND

The aim of the study was to examine the clinical success of high Dk (oxygen permeability) piggyback contact lens (PBCL) systems for the correction of contact lens intolerant keratoconus patients.

METHODS

Sixteen patients (29 eyes) who were not able to wear gas-permeable rigid lenses were included in this study. Hyper Dk silicone hydrogel (oxygen transmissibility or Dk/t = 150 units) and fluorosilicone methacrylate copolymer (Dk/t = 100 units) lenses were chosen as the PBCL systems. The clinical examinations included visual acuity and corneal observation by biomicroscopy, keratometer reading, and fluorescein staining before and after fitting the PBCL system.

RESULTS

INDICATIONS FOR USING PBCL SYSTEM WERE: lens stabilization and comfort, improving comfort, and adding protection to the cone. Visual acuities increased significantly in all of the patients compared with spectacles (P = 0). Improvement in visual acuity compared with rigid lenses alone was recorded in 89.7% of eyes and no alteration of the visual acuity was observed in 10.3% of the eyes. Wearing time of PBCL systems for most of the patients was limited time (mean 6 months, range 3-12 months); thereafter they tolerated rigid lenses alone except for 2 patients.

CONCLUSION

The PBCL system is a safe and effective method to provide centering and corneal protection against mechanical trauma by the rigid lenses for keratoconus patients and may increase contact lens tolerance.

Corneal Oxygen Uptake Associated With Piggyback Contact Lens Systems

PURPOSE

The purpose of this study was to determine the effects of static (without blinking) and dynamic (with blinking once every 5 seconds) wear of piggyback contact lens systems on corneal oxygen uptake.

METHODS

Corneal oxygen uptake rates were measured on the right eyes of 11 human subjects by using a polarographic electrode. Measurements were made for the normal open eye and after 5 minutes of wear of 4 rigid lens materials (Dk/t 0-82.5), 4 soft lens materials (Dk/t 13-122), and 16 combinations of rigid and soft lens materials. The piggyback systems were worn under both static and dynamic conditions. Repeated-measures analysis of variance was used to compare oxygen uptake rates associated with the wear of the rigid lens components, soft lens components, piggyback systems, and static versus dynamic wearing conditions. Spearman correlation coefficients and regression analyses were used to examine relationships between corneal oxygen uptake rates.

RESULTS

Measurable differences were found among oxygen uptake rates associated with the rigid lens components, soft lens components, and piggyback systems. Blinking resulted in no reduction in corneal oxygen uptake with the piggyback systems. Corneal oxygen uptake associated with the wear of the piggyback systems could not be predicted from those associated with the rigid and soft lens components of the systems.

CONCLUSIONS

Piggyback combinations of rigid and soft lens components with the highest transmissibilities resulted in the least increase in corneal oxygen uptake beyond that of the normal open eye.