Contact lens associated keratopathy

A case of bilateral subepithelial corneal deposits is reported in a 29-year-old disposable contact lens wearer. The deposits disappeared within 13 months of changing the disinfection system. A drug-related mechanism is possible. (Clin Exp Optom 1993; 76: 5: 172–173)     

Impact of contact lens material and design on the ocular surface

Background

To evaluate the impact on the ocular surface of a daily disposable hydrogel contact lens with high water content compared with two silicone hydrogel daily disposable lenses of lower water content.

Methods

The hydrogel lens assessed was made from nesofilcon A and the silicone hydrogel lenses were made of delefilcon A and stenfilcon A. Contact lens thickness was measured to assess material stability during daily wear, and ocular surface parameters such as tear film osmolarity, tear meniscus area and central corneal thickness were also assessed. Optical quality was analysed for all cases by means of wavefront aberrometry.

Results

The nesofilcon A was shown to be the thinnest lens (p < 0.001), while no differences in lens thickness were found between the two silicone hydrogel lenses (p = 0.495). No significant differences were found in tear film osmolarity, tear meniscus area, central corneal thickness or corneal aberrations, either as a function of the lens measured or time of use (p > 0.05).

Conclusion

In spite of having the thinnest lens and the highest water content, the hydrogel does not significantly impact on tear film and corneal swelling after one day of use in first‐time wearers.

     

The influence of lens conditioning on signs and symptoms with new hydrogel contact lenses

Background: Daily disposable contact lenses are considered to be the pinnacle of safe contact lens wear, yet it has been suggested that it takes some period of wear for the lens surface to reach optimal compatibility with the ocular surface. This study assesses the influence of brief treatment with a conditioning drop on the ocular response to new contact lenses over a single day of wear. Methods: The study was a single‐masked, paired (contralateral) comparison of the signs and symptoms with wear of new Acuvue 2 contact lenses pretreated with a conditioning agent containing carboxymethylcellulose (carmellose, CMC) against new lenses inserted directly from the blister pack. Sixty‐one subjects participated in the study, of whom 59 were considered eligible for data analysis. Subjects were also divided into symptomatic and asymptomatic lens wearers based on their overall comfort level in lens wear. Symptoms and signs were recorded at lens delivery and following eight hours of wear. Results: A set of slitlamp signs, comprising corneal staining (p < 0.05), limbal redness (p < 0.05), bulbar conjunctival hyperaemia (p < 0.05), bulbar conjunctival staining (p < 0.01) and palpebral conjunctival redness (p < 0.05) showed small but statistically significant (p < 0.05) end‐ofday mean values in favour of the lens that was conditioned with the rewetting agent. These data were supported by the proportion of subjects showing lower gradings with conditioned lenses versus unconditioned lenses, as follows: corneal staining (35 per cent versus 12 per cent, p <0.05), limbal redness (43 per cent versus 22 per cent, p < 0.05), bulbar conjunctival hyperaemia (50 per cent versus 15 per cent, p < 0.05), bulbar conjunctival staining (46 per cent versus 30 per cent, p < 0.1) and palpebral conjunctival hyperaemia (28 per cent versus 17 per cent, NS). For those subjects reporting symptoms with lens wear (n = 12), there was a statistically significant (p < 0.05) preference in terms of comfort as a result of preconditioning. Conclusions: The results of the investigation suggest that use of a conditioning agent can provide a more physiologically suitable environment for a new lens, thereby reducing the clinical signs associated with lens discomfort. The protocol used here, which is based on a statistical paradigm using standard pictorial grading scales, allows high sensitivity in detecting small changes in ocular parameters.     

Contact lens practice in Hong Kong in the new millennium

Purpose: We evaluated the contact lens services provided by practitioners in Hong Kong, the fitting habits of the contact lens practitioners and their attitudes regarding the use of orthokeratology (ortho‐k) and silicone hydrogel (SH) lenses for overnight wear. Methods: Questionnaires were sent to all Hong Kong optometrists licensed to prescribe contact lenses. Results: Two hundred and seventy‐five questionnaires (21 per cent) were returned. Most of die respondents (96 per cent) were employed in optical shops and worked in practices that provided contact lens services. The number of new/refit cases per practice per month was about 55, with die percentages of new and refit cases being 48 per cent and 52 per cent respectively. Eighty‐eight per cent of the patients were fitted widi soft lenses and 10 per cent were fitted widi rigid gas permeable (RGP) lenses. Fifty‐nine per cent of soft lens patients were fitted widi planned replacement (frequent replacement and disposable) soft lenses. Fifty per cent of soft lenses were low water content lenses and 85 per cent of RGP lenses were in low DK (≤ 40) material. Multipurpose solutions and soaking solutions with separate cleaner were die most commonly prescribed care regimens for soft and rigid lenses, respectively. Thirteen per cent of die practitioners provided ordio‐k services and die mean number of ortho‐k cases per mondi per ortho‐k practitioner was six, die majority of patients being children. DreimLens was die lens design most commonly used and Boston XO die most used material. However, 96 per cent of die responding practitioners had reservations about die practice of ortho‐k and die use of SH lenses for overnight wear. Conclusions: The contact lens market in HK is still dominated by soft lenses, particularly planned replacement lenses, whereas die percentage of RGP fits has changed little in the past decade. Few respondents used overnight ortho‐k and SH lenses in view of concerns about their efficacy and long‐term safety.     

Contact lens practice in Hong Kong

This survey represents an initial examination of contact lens practice in Hong Kong. It is based on a questionnaire survey of a group of contact lens practitioners in Hong Kong. The results bear out anecdotal observations such as the prevalence of soft lens fitting (spherical, daily wear soft lenses comprising 78 per cent of all contact lenses fitted) and the prominence of optical shops in the supply of contact lenses (69.7 per cent of the responding practices were of the ‘optical shop’ type premises). There was limited usage only of contact lenses for high astigmatism, aphakia or presbyopia. This low usage of speciality lenses may reflect the relative immaturity of the optometric profession in Hong Kong. One of the striking characteristics of Hong Kong is the rapidity of economic and social change. This is especially so in optometry now. In 1990-91 the Hong Kong Polytechnic has initiated a degree course in optometry and this coincides with the anticipated introduction of legislation to regulate the profession. It is intended that this survey should be a starting point for regular, comprehensive overviews of contact lens practice in Hong Kong.     

Mechanisms of dryness in soft lens wear— role of BUT and deposits

Background: The symptom of dryness in hydrogel lens wear is common but its origins remain poorly understood. To assess the theory that anterior lens surface interactions are responsible for the sensation of dryness during lens wear, 50 contact lens wearers were evaluated. Method: The Efron comfort scale was used to divide the group into subjects with comfortable lenses (26 control subjects) and those who were symptomatic (24 study subjects). The two groups were matched for gender, age, lens age, lens water content, lens wear experience and wearing environment. The only difference between the groups was that the non-symptomatic wearers had a greater wearing time (ANOVA, p = 0.005). Lens deposits and pre-lens tear thinning time (PLTTT) were assessed for each group. Results: The median PLTTT for the control group was three seconds (25th percentile, two seconds; 75th percentile five seconds); the study group had a median PLTTT of 3.5 seconds (25th percentile, 1.5 seconds; 75th percentile, four seconds). There was no significant difference in lens deposits and PLTTT between the comfortable and uncomfortable lens wearing groups, in particular, subjects with a short PLTTT (for example, less than four seconds) could still be comfortable. However, there was a significant inverse correlation between the grade of lens deposits and PLTTT (Spearman rank correlation, p = 0.01); a positive correlation between the grade of lens deposits and lens age (Spearman rank correlation, p = 0.001). Conclusions: The findings suggest that pre-lens tear stability is not necessarily an influence on comfort. It may be that the source of soft lens discomfort arises more from the exposed bulbar conjunctiva than the interaction between anterior lens surface and the tarsal conjunctiva. (Clin Exp Optom 1995; 78: 5: 168–175)     

Case report: Contact lens correction of keratoconus for contact sports

A previously undocumented technique was used to allow a keratoconic patient to play rugby. A combination of rigid gas permeable and soft bandage lenses was used.     

Contact lens in keratoconus

Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL.     

Contact lens practice in Saudi Arabia: practice and practitioner profile

Background: This paper presents the findings of the first national survey of contact lens practice in the Kingdom of Saudi Arabia. The purpose of the survey was to collect data to document the demography and characteristics of contact lens practice at this early stage of practice in the Kingdom. Method: A questionnaire was sent to practitioners in each of the practices in the selected cities. Results: Data from questionnaires revealed that 97 per cent of the eye clinics engaged in contact lens practice. The government owned 8.5 per cent of the clinics; others were private establishments owned by businessmen (72.3 per cent), ophthalmologists (16 per cent) and optometrists (3.2 per cent). The majority (84.5 per cent) of the clinics have been established within the past 10 years. The practitioners were mainly optometrists (70.2 per cent), many of them (60.6 per cent) had the Doctor of Optometry (OD) degree and half (50 per cent) had trained in the Philippines. Almost all of the practitioners (95.7 per cent) were male. Most respondents (52 per cent) were between the ages of 31 and 40 years and 61.4 per cent had been in contact lens practice for more than five years. Conclusion: The data presented here shows that most of the practitioners are foreigners. This is expected to change significantly in the near future when local practitioners replace the foreigners.     

Contact lens practice in Australia 1988–1989

Contact lens practitioners completed an annual survey of their prescribing patterns, usage of care solutions and attitudes to extended wear (EW). The survey period was July 1 1988 to June 30 1989 and the results were compared to those of previous, similar surveys. Many results were close to those in previous surveys, including the average number of pairs of lenses prescribed (95 new, 30 replacement), the proportion of contact lens fittings which were refits (40 per cent), the percentage of lenses prescribed which were soft (83 per cent) and the proportions of toric (soft 23 per cent, hard five per cent) and tinted (soft 39 per cent, hard 71 per cent) lenses prescribed. Results which differed markedly from previous surveys included the number of pairs of replacement lenses sold and the percentage of contact lens patients who were presbyopic. More than 90 per cent of lenses prescribed for EW were soft, although approximately 20 per cent of practitioners indicated that they would prefer to fit rigid gas permeable materials for EW. EW lenses were worn only on a true EW basis in six per cent of cases.     

In vitro and in vivo effects of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A

Background

Acuvue Oasys silicone hydrogel contact lenses (Senofilcon A) are used as bandage lenses and often combined with ophthalmic solutions in the treatment of ocular diseases. Concerns have been raised regarding the compatibility and effect of eye‐drop solutions on the bandage lenses, which have led to frequent replacement of lenses causing clinical problems. Some patients experience pain or discomfort during treatments and the accumulation of drugs and preservatives in lenses has been suggested as a possible reason. The aim with this study was to investigate the effect of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A in vitro and in vivo.

Methods

The effect of three common ophthalmic solutions Isopto‐Maxidex, Timosan and Oftaquix on Acuvue Oasys (Senofilcon A) bandage lenses was evaluated. An in vitro model method was developed where drug and preservative uptake by Acuvue Oasys was monitored with ultraviolet–visible spectroscopy and laser desorption ionisation mass spectrometry. Surface morphology changes of the lenses were evaluated using scanning electron microscopy. The method was then implemented for the in vivo pilot study evaluating lenses worn by patients.

Results

In vitro model study monitoring the drug and preservatives uptake showed that the active ingredients from all the eye drops together with preservatives were taken up by the lenses in significant amounts. For the in vivo study no traces of active ingredients or preservatives could be found on the worn and treated lenses regardless of time being worn or dosage profiles. The surface morphology changes in the in vivo study were also minor in contrast to the changes observed in the in vitro scanning electron microscopy images.

Conclusion

The in vivo results demonstrate minor effects of the ophthalmic solutions on the worn lenses. These results do not support the building up of preservatives and drugs on the contact lenses as the cause of pain or discomfort experienced by some patients, which is encouraging for the use of bandage lenses in combination with ophthalmic solutions.

     

Tear film dynamics of a new soft contact lens

Purpose

To present the objective metrics from a study that evaluated the clinical performance of a senofilcon A contact lens, both with and without a new manufacturing technique.

Methods

This was a single-site, five-visit, controlled, randomised, subject-masked, 2 × 2 crossover study (May–August 2021) with a 2-week lens dispensing period (bilateral wear) and weekly follow-up visits. Healthy adult (18–39 years), habitual spherical silicone hydrogel contact lens wearers were included. The High-definition (HD) Analyzer™ was used to objectively measure the lens-on-eye optical system resulting from the study lenses at 1-week follow-up. Measurements assessed were vision break-up time (VBUT), modulation transfer function (MTF) cutoff, Strehl ratio (SR), potential visual acuity (PVA) for 100% contrast and objective scatter index (OSI).

Results

Of the 50 enrolled participants, 47 (94.0%) were randomly assigned to one of the two possible lens wear sequences (test/control or control/test) and dispensed at least one study lens. The estimated odds ratio of VBUT > 10 s was 1.582 (95% confidence interval [CI]: 1.009 to 2.482) in test versus control lens. The least squares mean difference estimates of MTF cutoff, SR and PVA for 100% contrast between test versus control lens were 2.243 (95% CI: 0.012 to 4.475), 0.011 (95% CI: −0.002 to 0.023) and 0.073 (95% CI: −0.001 to 0.147), respectively. The estimated ratio of median OSI between test versus control lens was 0.887 (95% CI: 0.727 to 1.081). The test lens demonstrated superiority over the control lens with respect to VBUT and MTF cutoff. No serious adverse events were reported; eight adverse events (three ocular, five non-ocular) were indicated by six participants during the study.

Conclusion

The test lens demonstrated an increased probability of having a longer VBUT (>10 s). Future studies may be designed to assess the efficacy and long-term use of the test lens in a larger population.     

Wrinkled Edges on Soft Contact Lenses

ABSTRACT Wrinkling of the edges of some ultrathin soft contact lenses is reported, possibly as a result of partial dehydration in combination with heat disinfection and chemical preservatives. Wrinkling has been observed after a short period of wear, and generally does not cause any patient discomfort.     

Recovery of the water content of hydrogel contact lenses after use

The aim of the present study is to determine the amount and time of water-content recovery of ionic contact lenses (Surevue and Acuvue) and non-ionic contact lenses (Soflens 38, Soflens 66 and Optima 38) when submerged in maintenance solution for 9 h. Using a hand-held refractometer, we measured the water content of the lenses upon removal from the eye, and after 15, 30, 45 min, 1, 2 and 9 h in soaking solution. Both ionic lenses presented pre-wear water content of 58%, while two of the non-ionic ones (Soflens 38 and Optima 38) registered 38.6% and the third (Soflens 66) had 66%. We found a significant increase (p < 0.05) in water content after submersion in the Opti-Free solution for all the time periods studied and for all lenses. The water-content recovery was faster in the non-ionic lenses (Soflens 38, Soflens 66 and Optima 38) than in the ionic ones (Surevue and Acuvue), especially at 15 min. After 9 h in the soaking solution, the Surevue Acuvue, Soflens 38, Soflens 66 and Optima 38 lenses reached water-content recovery values of 99.7%, 99.6%, 99.8%, 99.8% and 99.6%, respectively, without significant differences (p > 0.05) between ionic and non-ionic lenses, although the non-ionic lenses reached slightly higher water-content values at all the times studied. These results indicate that when the refractometer technique is used to measure water content, the lens types used in this study regain their initial water-content values after 9 h in soaking solution. These data indicate the time needed for hydrogel contact lenses to reach their maximum water content after removal from the eye and submersion in maintenance solution. By ensuring maximum water content and minimum reduction of oxygen for the cornea, the specialist can help avoid clinical signs and symptoms related to low water content in the lenses.     

Effect of hydrogel lens wear on the major tear proteins during extended wear

Purpose: The purpose of the present study was to determine whether contact lens wear disturbed the levels of tear proteins and to further determine whether this was a transient or continuous disruption. Methods: Lactoferrin, lysozyme and albumin were quanti-tated from tears of neophyte patients and were compared with the levels of these proteins in contact lens wearers after one and six nights and 6 months of extended wear The quantitation of these tear proteins was performed by sandwich ELISA and turbidimetric assay. Results: Results showed that there were no statistically significant changes in the concentration of any of the proteins investigated. Conclusions: Extended wear of hydrogel lenses does not appear to alter the concentration of the major tear film proteins, indicating that the tear film is constantly replenished to maintain protein levels, which are depleted due to protein adsorption to the lens surface.     

Contact lens practice in Australia 1987–1988

Contact lens practitioners were surveyed in September 1988 on their prescribing patterns, use of care solutions and attitudes to extended wear (EW). During the period July 1, 1987 to June 30, 1988, the responding practitioners prescribed an average of 95 new pairs of contact lenses and provided an average of 96 pairs of replacement lenses. Thirty-eight per cent of fittings were refits, 80 per cent of lenses prescribed were soft lenses, 25 per cent and 12 per cent of soft and hard lenses respectively were toric, and 39 per cent and 87 per cent of soft and hard lenses respectively were tinted. Hydrogen peroxide was the most popular method for disinfecting soft lenses. Over 85 per cent of the respondents were prepared to fit contact lenses for EW use under certain circumstances, but only 15 per cent of all lenses prescribed were for any type of EW. Over 90 per cent of lenses prescribed for EW were soft. The most commonly recommended frequency for regular EW lens replacement was six-monthly and the mean number of nights of overnight wear recommended by the practitioners was 4.5 nights per week.     

软性角膜接触镜相关性表层点状角膜上皮病变临床分析与防治探讨

目的：对于软性角膜接触镜相关性表层点卷入 角膜上皮病变（ＳＣＬＩ－Ｒ－ＳＰＫ）进行临床分析,探讨防治措施。方法：对于２０２８例ＳＣＬ配戴者的验配进行回顾性研究,对于１６８例ＳＣＬ－Ｒ－ＳＰＫ患者进行临床分析,探讨防治措施。结果：ＳＣＬ－Ｒ－ＳＰＫ发生率为８．２８％。位于睑裂部者占８０．９５％,发生率为６．７１％。弥漫型者占１５．４８％,发生率为１．２８％。４．１７％配适偏紧,但有５５．２０％未再复     

Solving soft contact lens problems

Soft contact lens wearers encounter a variety of problems affecting their vision and comfort. Six patients with soft lens-related problems are discussed, illustrating the various sources of problems and approaches to their solution.     

新型的持续配戴高DK值的角膜接触镜

目的：随着镜片材料和制作工艺的高速发展，更加安全地过夜配戴角膜接触镜已逐渐成为可能。方法：对近年来涉及持续配戴高DK值角膜接触镜的一些研究论文进行综述。结果：新型的高DK值的硅胶和硅氟化物水凝胶镜片与传统的HEMA镜片相比，氧传导性高出6倍，这种新材料的镜片能够从根本上避免任何与组织缺氧有关的并发症。另一个明显的差异在于：新一代的硅胶镜片有更高的系数。而且在生理反应、匹配以及易操作性方面，与传统的低DK值镜片也明显不同。另外，尽管与组织缺氧相关的并发症不再存在，但是由于镜片覆盖在角巩缘360度范围，所以潜在的炎症反应以及机械性的损伤仍然不可避免。因此，制造者对涉及角膜生理反应的评估和对配适关系重要性的理解是这些新镜片获得成功过夜配戴的关键。结论：作为眼保健的从业者，视光医师必须了解持续配戴镜片的新进展情况、新材料潜在的副反应和配适特性。     

White light interferometry to characterize the hydrogel contact lens surface

Purpose: The aim of this study was to characterize, qualitatively and quantitatively, the surface morphology of four unworn conventional hydrogel contact lenses (Omafilcon, Hioxifilcon‐based, Nefilcon A and Ocufilcon B) by White Light Optical Profiling (WLOP). WLOP is an ideal technique for sampling larger areas as well as for higher measurement speed compared with other topography techniques used in contact lens studies. Methods: Surface roughness was assessed by WLOP in the Vertical Scanning Mode, with a Wyko^® NT1100, which is a non‐contact optical profiling system that provides high vertical resolution. Representative roughness parameters, the Average Roughness (R_a), Root‐mean‐square Roughness (R_ms), and Maximum Roughness (R_max), for areas of 625, 2500, 10829 and 67 646 μm² were calculated. Results: Higher R_a, R_ms and R_max values were obtained for larger areas in all lenses. Daily disposable contact lenses (Nefilcon A and Ocufilcon B) presented the highest R_a, R_ms and R_max values, the larger changes in these parameters becoming apparent with the increase in the measured area. Differences between lenses were less obvious when data from 625 and 2500 μm² area were compared. Conclusions: Daily disposable contact lenses showed the highest roughness surface. Analyzing larger areas might be adequate to detect differences between lenses in terms of surface characteristics, which may not be so obvious if smaller areas are studied.