Keratoconus in patients wearing rigid contact lenses. Part II: Adverse contact lens effects on the cornea

1991 ◽  
Vol 18 (1-2) ◽  
pp. 37-38 ◽  
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Rigid Contact

scholarly journals Preliminary Clinical Exploration of Scleral Lens Performance on Normal Eyes

2018 ◽  
Vol 2 (2) ◽  
pp. e14-e21
Author(s):  
Melissa Barnett ◽  
Jonathon Ross ◽  
Blythe Durbin-Johnson
Keyword(s):  
Visual Acuity ◽  
Contact Lens ◽  
Healthy Subjects ◽  
Contact Lenses ◽  
Front Surface ◽  
Contact Lens Wear ◽  
Factors Associated ◽  
Rigid Contact ◽  
Lens Wear ◽  
Spectacle Correction

Abstract Objectives: The purpose of this study was to evaluate the performance (i.e. vision, comfort and fit) of spherical and front-surface toric scleral lenses in subjects with regular, healthy corneas. Methods: Scleral lenses were fitin the eyes (n = 16) of healthy subjects (n = 9) with regular corneas, absent of pathology, and studied using an observational, multi-visit design. Lens fit was objectively evaluatedby an experienced practitioner.Following 1 month of successful lens wear, participants completedsubjective satisfaction surveys regarding the scleral lens wearing experience. Results:  According to participant surveys, scleral lenses were subjectively preferred over soft toric or gas permeable contact lenses in 88% of eyes, including in all eyes fit with a front-surface toric scleral lens (n = 3). Seventy-five percent (75%) of eyes achieved visual acuity of 0.1 logMAR or better, while all eyes with prior spectacle wear achieved visual acuity with a scleral lens within 1 Snellen line of spectacle correction. Seventy-five percent (75%) of eyes achieved good subjective comfort with a scleral lens. No participants reported poor subjective vision and/or comfort. Conclusions:  Our findings suggest that subjects preferred the performance of a scleral lens (spherical or front-surface toric) compared to a soft toric or gas permeable contact lens. Moreover, scleral lenses may provide a viable, alternative contact lens modality option for patients considering discontinuation of traditional soft toric and/or rigid contact lens wear; so long as the factors associated with hypoxia remain minimized. Key Words:  scleral lens; scleral contact lens; front-surface toric scleral lens; lens performance; normal eyes; healthy eyes

Nanophotonic Rigid Contact Lenses: Engineering and Characterization

2013 ◽  
Vol 633 ◽  
pp. 239-252
Author(s):  
Đuro Koruga ◽  
Dragomir Stamenković ◽  
Ivan Djuricic ◽  
Ivana Mileusnic ◽  
Jovana Šakota ◽  
...  
Keyword(s):  
Contact Lens ◽  
Materials Science ◽  
Contact Lenses ◽  
Base Material ◽  
Material Structure ◽  
Exclusion Zone ◽  
Characterization Methods ◽  
Rigid Contact ◽  
Complex Engineering

Contact lenses are a common optical aid to provide help with refractive anomalies of the human eye. Construction of contact lenses is a complex engineering task as it requires knowledge of optics, materials science, production and characterization methods for product quality. Besides correcting refractive anomalies, by using contact lenses it is possible to change the characteristics of light through the manipulation of material structure properties. Nanomaterials, such as fullerene C60, are candidates for the medium that interacts with light, thus changing its properties. During material syntheses for contact lenses, fullerenes are added to the base material and optical characteristics of the new nanophotonic material are compared with the base material. The engineering, manufacture and characterization of both a commercial and a new nanophotonic contact lens is presented in this paper. The interaction of water with both base and nanophotonic contact lens materials is described. Using experimental techniques, the phenomena of an exclusion zone (EZ) is also identified.

scholarly journals Anterior Eye Profilometry-guided Scleral Contact Lens Fitting in Keratoconus

2017 ◽  
Vol 6 (2) ◽  
pp. 97-100
Author(s):  
Roberto Soto-Negro
Keyword(s):  
Contact Lens ◽  
Potential Benefit ◽  
Contact Lenses ◽  
Spherical Model ◽  
Future Studies ◽  
Rigid Contact ◽  
The Stability ◽  
Fitting In ◽  
Contact Lens Fitting

ABSTRACT We report the case of a 35-year-old woman diagnosed with keratoconus since she was 18 years old and wearer of corneal rigid contact lenses (CLs). We refitted the case with the fully scleral CL ICD16.5 (Paragon Vision Sciences) for obtaining not only a successful visual restoration, but also a comfortable wear. We initiated the fitting with the spherical model of the CL, but it failed due to instability of the lens. We confirmed the presence of a clear asymmetry in the anterior scleral geometry in both eyes by using the profilometer eye surface profiler (ESP, Eaglet Eye), with a difference between nasal and temporal sagittal heights of 470 and 170 μm in right and left eyes respectively. Although this profile suggested the need for the fitting of a CL with significant peripheral toricity, we followed the manufacturer's guidelines and performed a trial with a CL of moderate peripheral toricity (125 μm of difference between steep and flat meridian). The stability of the CL failed again and finally a CL with a peripheral toricity close to that measured with the profilometer was fitted. With this lens, good visual performance, lens stability, and comfort was obtained and maintained during a 1-year follow-up. This case suggests that fully scleral CLs fitting might be optimized with the use of corneo-scleral profilometers, minimizing potentially the number of trials. This potential benefit should be investigated further in future studies. How to cite this article Piñero DP, Soto-Negro R. Anterior Eye Profilometry-guided Scleral Contact Lens Fitting in Keratoconus. Int J Kerat Ect Cor Dis 2017;6(2):97-100.

scholarly journals Clinical characteristics of keratoconus patients at the University of KwaZulu-Natal eye clinic

2020 ◽  
Vol 79 (1) ◽  
Author(s):  
Shishka Rupnarain ◽  
Nomvelo Madlala ◽  
Ntokozo Memela ◽  
Simpiwe Ngcobo ◽  
Nonkazimulo Shabalala ◽  
...  
Keyword(s):  
Contact Lens ◽  
Clinical Characteristics ◽  
Contact Lenses ◽  
Corneal Ectasia ◽  
Kwazulu Natal ◽  
Rigid Contact ◽  
The Mean ◽  
The University ◽  
Severe Grade ◽  
Eye Clinic

Background: Patients with keratoconus, which is a common corneal ectasia, often present to specialised clinics for management. Understanding the clinical characteristics of keratoconus patients can help improve knowledge of the presentation and management of this corneal ectasia and predict the needs of the clinic providing care for affected individuals.Aim: To describe the clinical characteristics of keratoconus patients attending the University of KwaZulu-Natal (UKZN) eye clinic.Setting: University of KwaZulu-Natal eye clinic.Methods: The study used a retrospective research design by reviewing the clinical record cards of patients attending the UKZN contact lens eye clinic over a 4-year period (January 2014 to December 2017). Data related to age, clinical characteristics and method of management of the keratoconus patients were extracted and analysed using descriptive statistics.Results: Just less than one-quarter of all patients (n = 1210) attending the UKZN contact lens eye clinic had keratoconus that was most often bilateral. The mean age at presentation was 25.2 ± 9.6 years with 74% of the sample being younger than 30 years. More than 90% (n = 419) of the sample reported refractive reasons as the primary reason for presenting to the clinic. The majority of the sample had severe keratoconus (n = 257) and rigid contact lenses were most commonly used for management of keratoconus patients.Conclusion: Keratoconus presents at an early age with a more severe grade and it is most commonly managed using rigid contact lenses. These findings should be considered for keratoconus screening, diagnosis and treatment programmes in KwaZulu-Natal.

scholarly journals The sag: A forgotten parameter in need of resurrection?

2016 ◽  
Vol 75 (1) ◽  
Author(s):  
Wayne D.H. Gillan
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Empirical Studies ◽  
Large Diameter ◽  
Rigid Contact

The advent of large-diameter rigid contact lenses (semi-scleral lenses) has necessitated renewed understanding of the concept of ‘the sag’ of a contact lens and/or cornea. This article reviews the concept of ‘the sag’ and how to calculate the sag for spherical and aspherical surfaces. Reviews of empirical studies investigating the sag of the eye are presented. Data for normal and keratoconic corneas for sags as measured with an Oculus Keratograph are also included. How to include empirical measurements obtained in practice, in the determination of a first-trial semi-scleral lens, is suggested.

scholarly journals The short-term effects of PMMA contact lens wear on keratometric behaviour: results for a single keratoconic cornea*

2010 ◽  
Vol 69 (2) ◽  
Author(s):  
E. Chetty ◽  
W. D. H. Gillan
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Corneal Curvature ◽  
Short Term ◽  
Multivariate Statistical ◽  
Contact Lens Wear ◽  
Rigid Contact ◽  
Dioptric Power ◽  
Control Study ◽  
Lens Wear

Keratometric behaviour is a multifaceted issue that many researchers have investigated for years. Many internal and external influences can have an effect on the cornea’s keratometric behaviour. This investigation forms a small part of a larger study that aims at determining the effects that rigid contact lenses might have on keratometric behaviour. This pilot study examined the keratometric behaviour of a single, mildly keratoconic cornea that was fitted with a polymethyl methacrylate (PMMA) contact lens. Sixty successive auto-keratometric measurements were taken immediately before and immediately after three hours of contact lens wear. The data obtained was transformed to dioptric power matrices and were analysed using multivariate statistical methods. This study showed that, at least in one keratoconic cornea, there appeared to be a statistically significant change in corneal curvature under the influence of a PMMA contact lens. The contact lens had also appeared to decrease variation in corneal curvature. There was no control study done on this eye therefore the effects of diurnal variation, if any, could not be established. (S Afr Optom 2010 69(2) 69-76)

scholarly journals Patient comfort following thirty minutes of lens wear: piggy-back versus conventional rigid-lens wear

2014 ◽  
Vol 73 (1) ◽  
Author(s):  
W. D.H. Gillan
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Normal Subjects ◽  
Patient Comfort ◽  
Lens System ◽  
Common Complaint ◽  
Minute Period ◽  
Rigid Contact ◽  
Lens Wear

Discomfort when wearing contact lenses, especially rigid contact lenses, is a common complaint amongst neophyte as well as experienced contact lens wearers. Wearing a piggy-back system of contact lenses has been shown to improve comfort and wearing time, especially in keratoconic subjects. Twenty two normal subjects wore a rigid lens or a piggy-back system of lenses for thirty minutes and after a thirty minute break swopped the mode of lens wear and wore the second modality for a thirty minute period. This study suggests that a piggy-back lens system provides improved comfort compared to wearing a rigid lens on its own. The order of lens wear might, however, influence the perceived comfort.

scholarly journals The short-term effects of PMMA and RGP contact lens wear on keratometric behaviour: a pilot study*

2010 ◽  
Vol 69 (4) ◽  
Author(s):  
E. Chetty ◽  
W. D. H. Gillan
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Control Sample ◽  
Control Group ◽  
Diurnal Changes ◽  
Short Term ◽  
Contact Lens Wear ◽  
Rigid Contact ◽  
Lens Wear ◽  
Short Term Effects

This article represents the preliminary findings of a larger study that included 24 subjects that were equally divided into three groups, namely, the PMMA (polymethyl methacrylate) group, the RGP(rigid gas permeable) group and the control group. The aim of this study was to establish the short term effects (if any) of PMMA and RGP contact lens wear on keratometric behaviour. A controlsubject was also included in the study to establish a reference fornormal diurnal changes in keratometric behaviour. Fifty successive auto-keratometric measurements were taken before and immediately after three hours of rigid contact lens wear for the first subject in the PMMA group and the first subject in the RGP group (experimental samples). Fifty successive auto-keratometric measurements were also taken on the first subject of the control group before and immediately after three hours of no lens wear (control sample). Data collected were analysed using multivariate statistical methods that in the past have been used infrequently in this area of study. This investigation revealed that, at least in these two randomly selected subjects, rigid contact lens wear appears to  influence keratometric behaviour (PMMA contact lenses more so than RGP contact lenses). (S Afr Optom 2010 69(4) 173-181)

Optimum Infinite is a new era of oxygen permeability material for contact lenses

The Eye ◽  
2020 ◽  
Vol 22 (129) ◽  
pp. 44-46
Author(s):  
Mark Eddleston
Keyword(s):  
Contact Lens ◽  
Oxygen Permeability ◽  
Contact Lenses ◽  
New Era ◽  
Lens Material ◽  
Insight Into

Optimum Infinite is a new GP contact lens material, with an oxygen permeability of 180 barrer and was launched by Contamac at the GSLS 2019. This article provides an insight into the development and characteristics of this breakthrough material.

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