Scleral contact lenses for visual rehabilitation in keratoconus and irregular astigmatism after refractive surgery

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.

Miniscleral Contact Lens in Pediatric Age Group: Indications, Safety, and Efficacy

OBJECTIVE

To report indications, fitting feasibility, and safety of miniscleral design (MSD) lenses in children.

METHODS

Medical records of patients aged <18 years at the time of referral to Contact Lens Clinic of Farabi Eye Hospital, because of inadequate spectacle-corrected visual acuity, rigid gas-permeable or soft contact lens intolerance, and ocular surface disease were reviewed. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), best-corrected vision with the lens (CCVA), lens parameters, and comfortable daily wearing time (CDWT) were documented.

RESULTS

Seventy-two eyes of 52 pediatric patients were fitted with MSD lens over a 9-year period. The indications for MSD lens fitting were keratoconus (29 eyes), corneal scarring from ocular trauma (16 eyes), ocular surface diseases (25 eyes), and postkeratitis corneal scar (2 eyes). The average UCVA and the mean difference between CCVA and BSCVA were 1.20 and 0.55 logarithm of the minimal angle of resolution, respectively, which shows statistically significant improvement. This significant increase in vision was even seen in those who were referred for the management of ocular surface diseases. The mean CDWT for most patients was 10 hr/day.

CONCLUSION

Miniscleral design lens can be used as a safe and helpful modality to provide good vision and comfort in children experiencing ectatic disorders, traumatic corneal scars, and ocular surface diseases.

Comparison of Wavefront-guided and Best Conventional Scleral Lenses after Habituation in Eyes with Corneal Ectasia

SIGNIFICANCE

Visual performance with wavefront-guided (WFG) contact lenses has only been reported immediately after manufacture without time for habituation, and comparison has only been made with clinically unrefined predicate conventional lenses. We present comparisons of habitual corrections, best conventional scleral lenses, and WFG scleral lenses after habituation to all corrections.

PURPOSE

The purpose of this study was to compare, in a crossover design, optical and visual performance of eyes with corneal ectasias wearing dispensed best conventional scleral lens corrections and dispensed individualized WFG scleral lens corrections.

METHODS

Ten subjects (20 eyes) participated in a randomized crossover study where best conventional scleral lenses and WFG scleral lenses (customized through the fifth radial order) were worn for 8 weeks each. These corrections, as well as each subject's habitual correction and normative data for normal eyes, were compared using (1) residual higher-order aberrations (HORMS), (2) visual acuity (VA), (3) letter contrast sensitivity (CS), and (4) visual image quality (logarithm of the visual Strehl ratio, or logVSX). Correlations were performed between Pentacam biometric measures and gains provided by WFG lenses.

RESULTS

Mean HORMS was reduced by 48% from habitual to conventional and 43% from conventional to WFG. Mean logMAR VA improved from habitual (+0.12) to conventional (-0.03) and further with WFG (-0.09); six eyes gained greater than one line with WFG over conventional. Area under the CS curve improved by 26% from habitual to conventional and 14% from conventional to WFG. The percentage of the eyes achieving normal levels were as follows: HORMS, 40% for conventional and 85% for WFG; VA, 50% for conventional and 85% for WFG; and CS, 60% for conventional and 90% for WFG. logVSX improved by 16% from habitual to conventional and 25% further with WFG. Reduction in aberrations with WFG lenses best correlated with posterior cornea radius of curvature.

CONCLUSIONS

Visual performance was superior to that reported with nonhabituated WFG lens wear. With WFG lenses, HORMS and logVSX significantly improved, allowing more eyes to reach normal levels of optical and visual performance compared with conventional lenses.

Automatic Identification and Representation of the Cornea-Contact Lens Relationship Using AS-OCT Images

The clinical study of the cornea-contact lens relationship is widely used in the process of adaptation of the scleral contact lens (SCL) to the ocular morphology of patients. In that sense, the measurement of the adjustment between the SCL and the cornea can be used to study the comfort or potential damage that the lens may produce in the eye. The current analysis procedure implies the manual inspection of optical coherence tomography of the anterior segment images (AS-OCT) by the clinical experts. This process presents several limitations such as the inability to obtain complex metrics, the inaccuracies of the manual measurements or the requirement of a time-consuming process by the expert in a tedious process, among others. This work proposes a fully-automatic methodology for the extraction of the areas of interest in the study of the cornea-contact lens relationship and the measurement of representative metrics that allow the clinicians to measure quantitatively the adjustment between the lens and the eye. In particular, three distance metrics are herein proposed: Vertical, normal to the tangent of the region of interest and by the nearest point. Moreover, the images are classified to characterize the analysis as belonging to the central cornea, peripheral cornea, limbus or sclera (regions where the inner layer of the lens has already joined the cornea). Finally, the methodology graphically presents the results of the identified segmentations using an intuitive visualization that facilitates the analysis and diagnosis of the patients by the clinical experts.