Enhancing the approach to selecting eyewear (EASE): A multi-centre, practice-based study into the effect of applying contact lenses prior to spectacle dispensing

Purpose

To examine the impact of contact lens application in non-contact lens wearers prior to spectacle dispensing.

Methods

Ninety-one eligible subjects with no previous contact lens experience were randomly assigned into either a test group (52 subjects) or control group (39 subjects). The former group was offered contact lenses before spectacle dispensing. The latter group proceeded to spectacle dispensing in the normal way without being offered contact lenses. The response to the offer of contact lenses, fit success, the impact on the spectacle dispensing process and the longer term purchase of contact lenses were measured and compared for the test and control groups.

Results

Of the test group, 46 (88%) agreed to try contact lenses. All subjects were suitable for contact lenses after a slit lamp examination and lenses were successfully fitted to 45 of the 46 subjects (98%). The test group reported a superior subjective spectacle dispensing experience and spent £267 ± 143 (mean ± standard deviation) on their spectacle frames and lenses, 32% more than the control group (£202 ± 128). At 3 months post dispensing, 17 test patients (33% of original cohort) had purchased contact lenses compared with five control subjects (13%) (p = 0.001).

Conclusions

The opportunity to try contact lenses prior to spectacle dispensing was well received by subjects who generally reported a very positive experience. In particular, contact lenses assisted in seeing frame detail and suitability for wear. One third of subjects proceeded to purchase contact lenses. We recommend that practitioners consider offering contact lenses to all suitable patients who are proceeding to spectacle dispensing to optimise the dispensing process and to provide an opportunity to try contact lenses.     

Prevalence of contact lens related complications in a tertiary eye centre in India

Aim

To determine the prevalence of contact lens related complications in a tertiary eye care centre in India.

Methods

A retrospective review of the charts of 1255 patients who visited our contact lens clinic during 2001-2004 was conducted. The inclusion criteria included patients of at least 18 years of age, having refractive errors and keratoconus. Exclusion criteria included previous corneal surgeries and pediatric patients. 190 subjects with lens related complications were identified from among 923 patients who were using lenses.

Results

The prevalence of contact lens complications was 20.58%. Females with complications were more common (59.47%). The complications were more common in students. The most common complications were contact lens induced papillary conjunctivitis (CLPC) (6.39%), corneal vascularisation (4%), and superficial punctate keratitis (SPK) (3.5%). The total complications were less prevalent in patients wearing rigid gas permeable (RGP) lenses as compared to soft contact lenses. Infectious keratitis was noted in 8 eyes. Pseudomonas aeuroginosa was the most common organism isolated. The average daily wear with RGP lenses was 11.04 ± 3.7 h and 10.96 ± 3 h with soft contact lens. The highest number of complications was noted in 47.89% patients who were wearing lenses for excess of 11 h. The number of patients with complications arising due to sleeping with the lenses was 74 (38.95%).

Conclusion

Prevalence of contact lens complications was more in soft contact lens wearers compared to RGP wearers. CLPC was the most common complication followed by vascularisation and SPK.     

Predicted tear layer oxygen tensions under two designs of silicone hydrogel toric lenses

Introduction

The goal of this study was to apply a theoretical analysis of the relationship between contact lens oxygen transmissibility and tear layer oxygen tension to silicone hydrogel toric lenses and thereby model the success of such lenses in decreasing corneal hypoxia.

Method

Lens thickness was measured at different points along the vertical meridian of one prism-ballasted, one dynamic-stabilized silicone hydrogel toric lens design, and one control “traditional” hydrogel toric lens design. Using lens thickness measurements and the nominal oxygen permeability values of these three lens designs, the subsequent oxygen tension in the tear layer trapped between the contact lens and the anterior cornea (P2) were calculated for both open- and closed-eye conditions using a single corneal chamber model with a personal computer program.

Results

We found that cylindrical powers, regardless of lens materials, did not have a statistically significant effect on lens thickness (F = 0.30, p = 0.5834) to the limitation of our measurements, while contact lens type, spherical power, location on lens, and axis of cylindrical power were all found to do so. When multi-factor ANOVA was applied to the lens thickness and P2 data, contact lens location had a statistically significant effect on P2 values for both prism-ballasted (F = 640.16, p < 0.0001) and dynamic-stabilized toric lenses (F = 352.85, p < 0.0001). When the same statistical methodology was used to compare the relative performance of all three lenses on P2 during daily wear, the average P2 values for the three different lens brands were all statistically significantly different, while under closed-eye conditions the average P2 values for both silicone hydrogel toric lenses were no longer statistically significantly different (F = 1.00, p = 0.3178).

Conclusion

Assuming that the critical P2 was 100 mmHg, we predicted that silicone hydrogel toric soft lenses would provide reasonable anterior corneal oxygenation, certainly much enhanced over the environment predicted under traditional hydrogel designs, especially during daily (e.g. open eye) wear. Substantial corneal hypoxia continued to be predicted during extended wear of all lenses, but especially so with the use of traditional hydrogels.     

Rigid gas permeable contact lenses: Out in the cold

Introduction

Rigid gas permeable (RGP) contact lens wearers may experience episodes of lens fracture during handling. In this paper, we report the case of a keratoconic contact lens wearer whose lens fractured whilst being handled at sub-zero temperatures. Subsequent studies illustrate how PMMA and RGP contact lenses behave when exposed to sub-zero temperatures.

Methods

Using a previously validated custom-built strain gauge we have measured the force required to invert RGP contact lenses (Fluroperm, DK30-DK151, PMMA and Aquasil; dioptric power −2.00DS) under different temperature conditions.

Results

It was found that RGP lenses, frozen to −7 °C, required on average 15% less force to cause inversion than when stored at room temperature, regardless of material. It was also found that without due care, lenses of all materials fractured more easily after having been frozen, than lenses kept at room temperature. Fracture rates rose from 8% to 83% if lenses were stored wet (at −7 °C) as opposed to dry.

Conclusion

The authors conclude that practitioners should consider inappropriate contact lens storage and handling as a possible reason for otherwise unexplained acute RGP contact lens fracture.     

Struggle with hydrogel CL wear increases with age in young adults

Purpose

To report the symptoms and experiences associated with habitual hydrogel (Hyd) and silicone hydrogel (SiHy) contact lenses (CLs) among young adults and measure their association with age.

Methods

Questionnaire responses from 699 Hyd and 183 SiHy wearers were analyzed to test the association of age with features indicating struggle with CL wear. Prevalence by age was compared between groups with Pearson's chi-square and within groups with Spearman's correlation coefficient.

Results

Hyd and SiHy groups were similar for sex and age distribution. Diagnosis of dry eye increased with age in the Hyd wearers from 10.6% to 21.1% (18-24 vs. 30-35 years), but was approximately 19% in the SiHy wearers across age. Adverse environments caused more discomfort with Hyd than SiHy lenses and Hyd wearers’ discomfort increased with age (smoky (p = 0.0001), dry air environments (p = 0.002), after napping or sleeping (p = 0.004). More Hyd wearers considered discontinuation of CL wear with age, from 4.6% to 14.2% (18-24 vs. 30-35 years, p < 0.04), but the proportion remained steady at 9% across age for SiHy wearers (p = 0.46).

Conclusions

From 18 to 35 years, hydrogel CL wearers reported increasing struggle with CL wear and more negative ratings compared to SiHy wearers. Older hydrogel CL wearers were also more likely to consider discontinuing CL wear compared with younger hydrogel or silicone hydrogel CL wearers in general. Young adult CL wearers should be routinely queried directly about specific aspects of CL wear in order to determine whether different lens types should be prescribed to avoid abandonment of CL wear.     

The therapeutic and optical application of a rigid gas permeable semi-limbal diameter contact lens

Purpose

To evaluate the therapeutic and optical application of a semi-limbal diameter (S-LIM) rigid gas permeable (RGP) contact lens.

Method

A retrospective non-comparative case series of 14 consecutive patients (22 eyes) who were referred to one senior optometrist for the fitting of S-LIM contact lenses at Moorfields Eye Hospital. The cases comprised of 11 patients (17 eyes) with keratoconus, 1 patient (2 eyes) post-surgical ectasia from previous LASIK, 1 (1 eye) post-graft patient, and 1 patient (2 eyes) who required corneal protection secondary to lagophthalmos. These patients had failed previously with other lens designs because of lens intolerance, unstable vision, chronic 3 and 9 o’clock corneal staining, and inadequate corneal protection for the patient with lagophthalmos. A conventional method of using diagnostic lenses with fluorescein assessment was adopted in fitting the S-LIM lenses.

Results

The median duration of problems encountered with previous lenses was 4 years (range 0.5-10 years). The median visual acuity with the S-LIM lens was 6/9 (range 6/5-6/24). A median of 1 diagnostic lens (range 1-3 lenses) was required to achieve a satisfactory fit. At the last recorded follow-up, 10 patients (14 eyes) had no clinically observable problem and were wearing their lenses with a median wearing time of 8 h per day (range 1-18 h). The median duration of follow up was 6 months (range 2-18 months). One patient (1 eye) abandoned lens wear because of satisfactory unaided vision.

Conclusion

The use of a semi-limbal diameter lens can be an effective modality in patients with intolerance to other lens designs. However, lens modification from the standard design and the use of ocula lubricants are often required to optimise lens fit and to enhance tolerance.     

A comparison of regimen methods for the removal and inactivation of bacteria, fungi and Acanthamoeba from two types of silicone hydrogel lenses

Purpose

To compare the antimicrobial efficacy of commercial contact lens solutions when used according to the manufacturers’ recommended regimens with two types of silicone hydrogel lenses.

Methods

Four multipurpose contact lens care solutions were examined, representing manufacturer recommended regimens of “rub & rinse”, “no rub, rinse” or “no rub, no rinse”. Test organisms were Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Fusarium solani, Candida albicans and Acanthamoeba castellanii (trophozoites and cysts). Organisms, in the presence of organic soil, were inoculated on to Acuvue Oasys or Air Optix lenses and subjected to the solution manufacturer's recommended regimen. The number of surviving organisms on the lenses and in the soak solution was enumerated in accordance with ISO 14729.

Results

ISO 14729 dictates that for a given organism the combined average number of surviving microbes from the lenses and disinfectant soaking solution must be ≤10 colony forming units (cfu)/ml. By this criterion, only Complete Easy Rub (“rub & rinse” regimen) gave satisfactory results for all bacteria, fungi and Acanthamoeba with both lens types. Solutions employing “no rub, rinse” were less satisfactory but significantly better than “no rub, no rinse”. Significant differences were found in organism survival on the lenses with greater numbers remaining on the Air Optix compared to Oasys (p < 0.01-0.0001).

Conclusion

The findings of this study demonstrate that the use of a manual rubbing step is more effective than rinsing or soaking alone in removing pathogenic microbes from silicone hydrogel lenses. Accordingly, it would seem prudent to recommend that contact lens care systems include a rub step as part of the hygiene regimen.     

Knowledge,usage and barriers associated with contact lens wear in Ghana

Background

Despite findings that contact lens wear for vision correction provides better quality of life than spectacles, contact lens use in developing countries is low. This study evaluated knowledge, usage and barriers associated with contact lens wear among spectacle wearers in Cape Coast, Ghana.

Corneal shape changes induced by first and second generation silicone hydrogel contact lenses in daily wear

Purpose

To compare the corneal topographical changes induced by two first and second generation silicone-hydrogel (SiH) contact lenses after 3 months of daily wear (DW).

Methods

Prospective, consecutive case-series in which patients wore one of 3 different contact lenses (either the first generation SiH Focus Night & Day, the second generation SiH Acuvue Oasys or the monthly disposable Soflens 38 hydrogel lens as control group) on a DW basis for 3 months. Over-refraction, visual acuity, mean keratometry, corneal astigmatism, corneal eccentricity, superficial regularity and superficial asymmetry indices were monitored over the 3-month period.

Results

Nineteen eyes of 10 patients completed the study. Seven Focus Night & Day, 7 Acuvue Oasys and 5 Soflens 38 contact lenses were fitted. There were no significant changes between any of the parameters measured at the 3-month visit in any of the SiH groups (non-parametric Wilcoxon test, p > 0.05). However, the control group (Soflens 38) showed statistically significant changes regarding mean keratometry, corneal astigmatism and corneal eccentricity (p < 0.05). Three patients wearing the first generation SiH showed adverse events of different degree related to their high modulus of elasticity.

Conclusions

After 3 months of DW, wearers of first and second generation SiH lenses showed greater corneal stability than hydrogel monthly disposable contact lenses users regarding commonly used topographic corneal shape indices. However, complications related to the mechanical properties of first generation SiH were seen in three patients in the follow-up time.     

The significance of hand wash compliance on the transfer of dermal lipids in contact lens wear

Aim

The aim of this study was to assess the impact of hand washing regimes on lipid transference to contact lenses. The presence of lipids on contact lenses can affect visual acuity and enhance spoilation. Additionally, they may even mediate and foster microbial transfer and serve as a marker of potential dermal contamination.

Methods and materials

A social hand wash and the Royal College of Nursing (RCN) hand wash were investigated. A ‘no-wash regime’ was used as control. The transfer of lipids from the hand was assessed by Thin Layer Chromatography (TLC). Lipid transference to the contact lenses was studied through fluorescence spectroscopy (FS).

Results

Iodine staining, for presence of lipids, on TLC plates indicated the ‘no-wash regime’ score averaged at 3.4 ± 0.8, the social wash averaged at 2.2 ± 0.9 and the RCN averaged at 1.2 ± 0.3 on a scale of 1-4. The FS of lipids on contact lenses for ‘no washing’ presented an average of 28.47 ± 10.54 fluorescence units (FU), the social wash presented an average of 13.52 ± 11.12 FU and the RCN wash presented a much lower average 6.47 ± 4.26 FU.

Conclusions

This work demonstrates how the method used for washing the hands can affect the concentration of lipids, and the transfer of these lipids onto contact lenses. A regime of hand washing for contact lens users should be standardised to help reduce potentially transferable species present on the hands.     

Contact lens profile: A tale of two countries

Introduction

This study investigated the modality, type and duration of contact lens wear as well as compliance and hygiene related issues (hand and case hygiene, use of tap water, dozing and overnight wear) in the UK and Germany. Questionnaires were collected anonymously from 417 UK and 767 German patients attending optometric practices for contact lens appointments. It is the seventh of a series of contact lens wearer profiles conducted since 2000.

Results

The proportion of rigid gas permeable lenses worn was significantly higher at 55.4% in Germany, compared to 16.1% in the UK. Overall, a significantly larger proportion of German participants used tap water to rinse their lenses and cases (P < 0.001). Also, German respondents changed their lens cases less frequently (p < 0.001). Fewer UK than German respondents stated they washed their hands before lens insertion (p = 0.009), removal (p = 0.01), before eating (p < 0.001). German participants were less likely to wash their hands before preparing food (p = 0.042) and after using the toilet (p = 0.002). The two sample groups differed significantly regarding the care regimens they used for their CLs (p < 0.001).

Conclusion

The differences between Germany and the UK highlighted in this study were caused by differences in legal regulations, plumbing and practitioners’ guidance. Although many of the questions relating to hygiene differed statistically between the two participating sample groups, the absolute differences in figures were not considered to be large.     

Activity of a melimine derived peptide Mel4 against Stenotrophomonas,Delftia, Elizabethkingia,Burkholderia and biocompatibility as a contact lens coating

Purpose

To determine the antimicrobial activity of the melimine derived peptide Mel4 against Delftia, Stenotrophomonas, Elizabethkingia, Burkholderia and to investigate biocompatibility of Mel4 as an antimicrobial coating on contact lenses in animals and humans.

Contact lens induced papillary conjunctivitis with silicone hydrogel lenses

Purpose

To describe the refitting of a soft lens wearer into a silicone hydrogel lens due to neovascularization. This change, in turn, caused contact lens induced papillary conjunctivitis (CLPC) and a further refitting was necessary.

Methods

The patient was refit into a high Dk surface treated silicone hydrogel with a high modulus value. A second refitting was undertaken into a lower Dk silicone hydrogel contact lens with a lower modulus value which had no surface treatment but incorporated an internal wetting agent.

Results

A high Dk/t lens was used to resolve existing neovascularization and chronic hyperaemia. Subsequently, CLPC response occurred, possibly due to a combination of factors, resulting in irritation of the palpebral conjunctiva. This resulted in temporary lens discontinuation. A second silicone hydrogel lens was fit, along with the use of a non-preserved care system, which led to improvement and eventual resolution of the condition.

Conclusion

High Dk silicone hydrogel lenses have shown excellent efficacy in resolving hypoxic complications such as neovascularization and hyperaemia. However, attention needs to be paid to their potential effect on the upper tarsal plate. More than one silicone hydrogel lens may be needed to help resolve these issues.     

Corneal conjunctivalization management with high Dk RGP contact lenses

Purpose

To describe the management of corneal conjunctivalization with a high Dk RGP contact lens (CL) fitting.

Methods

A high Dk RGP CL (Menicon Z-alpha Dk = 189, Japan) was fitted, after temporary suspension of CL wear (6 months and 3 weeks), in two patients (a 36-year-old female and a 38-year-old male) who had corneal conjunctivalization secondary to low Dk soft CL wear. Both patients had worn their soft CLs 12-14 h per day without symptoms for the previous 18-20 years.

Results

After 9-15 months of high Dk RGP wear, all signs of corneal conjunctivalization had disappeared (corneal vascularization, late fluorescein stain, etc.) and patients wore their RGP CL comfortably. Corneal conjunctivalization was resolved with non-invasive procedures (temporary discontinuation, preservative-free artificial tears and high Dk RGP CL fitting) and thus other treatments (topical or surgical treatments such as limbus transplantation, amniotic membrane transplant or others) were not necessary.

Conclusions

Short temporary suspension of CL wear (3 weeks), preservative-free artificial tears and refitting with high oxygen permeability RGP CL may be an alternative for the management of corneal conjunctivalization secondary to CL wear.     

Simplified recording of soft contact lens fit

Purpose

To determine the critical fitting characteristics of modern soft contact lens fits and from this to devise a simplified recording scheme.

Methods

Ten subjects (aged 28.1 ± 7.4 years) wore eight different modern soft contact lenses. Video was captured and analysed of blink (central and up-gaze), excursion lag (up, down, right and left gaze) and push-up movement, centration and coverage.

Results

Lens centration was on average close to the corneal centre. Movement on blink was significantly smaller in up-gaze than in primary-gaze (p < 0.001). Lag was greatest in down-gaze and least in up-gaze (p < 0.001). Push-up test recovery speed was 1.32 ± 0.73 mm/s. Overall lens movement was determined best by assessing horizontal lag, movement on blink in up-gaze and push-up recovery speed. Steeper lens base-curves did not have a significant effect on lens fit characteristics. Contact lens material did influence lens fit characteristics, particularly silicone-hydrogels which generally had lower centration and a faster push-up speed of recovery than HEMA lenses (p < 0.05).

Conclusion

Lag on vertical gaze, and movement on blink in primary gaze generally provide little extra information on overall lens movement compared to horizontal lag, movement on blink in up-gaze and push-up recovery speed. They can therefore be excluded from a simplified recording scheme. A simplified and comprehensive soft contact lens fit recording system could consist of a cross-hairs indicating the centre of the cornea; a circle to indicate the lens centration; a mark on the relevant position of the circle to indicate any limbal incursion; a grade (B) below for movement with blink in up-gaze, a grade (L) to the side for horizontal lag and a grade above (P) for the assessed push-up recovery speed.     

Performance evaluation of delefilcon a water gradient daily disposable contact lenses in first-time contact lens wearers

Purpose

To evaluate the tolerability of and subject and investigator satisfaction with delefilcon A (DAILIES TOTAL1^®) daily disposable contact lenses in first-time contact lens wearers.

Descemet's membrane detachment attributed to the mechanical forces of airbag deployment

Purpose

A patient who developed a Descemet's membrane detachment 3 weeks following airbag deployment is reported.

Case report

A hydrogel contact lens wearer (extended wear) presented to her primary eye care provider with a painful red eye that had been treated with pressure patching the previous day at a hospital emergency room. Examination revealed full thickness corneal edema localized in the temporal region of the left eye, a corneal infiltrate with an overlying epithelial defect, and an anterior chamber reaction with marked temporal injection. The patient was referred to a corneal specialist after the cornea failed to respond to anti-microbial treatment. Probing of the history revealed that the patient had recently sustained an automobile accident in which the front air bags had deployed. Confocal microscopy revealed that Descemet's membrane was detached, presumably secondary to the mechanical forces of airbag deployment. The patient recovered normal vision after 3 weeks of topical therapy and ultimately returned to successful contact lens wear.

Discussion

Although Descemet's membrane detachment is an uncommon complication of airbag deployment, it is important to exclude this possibility because delayed diagnosis and treatment may compromise the corneal endothelium, predispose the cornea to chronic edema, and result in permanent vision loss. An awareness of the spectrum of injuries resulting from airbag deployment should facilitate early diagnosis and treatment, particularly in situations where the etiology of the presenting eye condition is not readily apparent.     

Fitting the post-keratoplasty cornea with hydrogel lenses

Purpose

We report two cases who have undergone penetrating keratoplasty (three eyes total), and who were fitted with hydrogel lenses.

Methods

In the first case, a 28-year-old male presented with an interest in contact lens fitting. He had undergone corneal transplantation in both eyes, about 5 years ago. After topographies and trial fitting were performed, it was decided to be fitted with reverse geometry hydrogel lenses, due to the globular geometry of the cornea, the resultant instability of RGPs, and personal preference. In the second case, a 26-year-old female who had also penetrating keratoplasty was fitted with a hydrogel toric lens of high cylinder in the right eye.

Results

The final hydrogel lenses for the first subject incorporated a custom tricurve design, in which the second curve was steeper than the base curve and the third curve flatter than the second but still steeper than the first. Visual acuity was 6/7.5 RE and a mediocre 6/15 LE (OU 6/7.5). The second subject achieved 6/4.5 acuity RE with the high cylinder hydrogel toric lens.

Conclusions

In corneas exhibiting extreme protrusion, such as keratoglobus and some cases after penetrating keratoplasty, curvatures are so extreme and the cornea so globular leading to specific fitting options: sclerals, small diameter RGPs and reverse geometry hydrogel lenses, in order to improve lens and optical stability. In selected cases such as the above, large diameter inverse geometry RGP may be fitted only if the eyelid shape and tension permits so. The first case demonstrates that the option of hydrogel lenses is viable when the patient has no interest in RGPs and in certain cases can improve vision to satisfactory levels. In other cases, graft toricity might be so high that the practitioner will need to employ hydrogel torics with large amounts of cylinder in order to correct vision. In such cases, the patient should be closely monitored in order to avoid complications from hypoxia.     

Mechanisms of superficial micropunctate corneal staining with sodium fluorescein: The contribution of pooling

Purpose

To establish if sodium fluorescein (SFL) dye accumulation within intercellular spaces on the ocular surface contributes to the appearance of superficial punctate corneal staining.

Methods

Thirteen subjects bilaterally wore PureVision™ lenses that had been pre-soaked in ReNu MultiPlus^® multipurpose solution. After 1 h of lens wear, corneal staining with SFL was assessed using a standard slit-lamp technique. Participants who presented with bilateral, corneal staining were selected for further evaluation. A randomly selected eye was rinsed with saline three times. Fellow eyes (control) received no rinsing. After each rinse, the appearance of SFL staining was recorded without any further instillation of the dye. To eliminate any confounding effects of staining due to residual fluorescein in the tear menisci, corneal staining was induced in freshly excised, isolated, rabbit eyes by topical administration of 0.001% PHMB and staining, rinsing and grading were performed as above.

Results

Nine out of 13 subjects presented with bilateral diffuse corneal staining (mean grade ± SD: 2.4 ± 0.7). The mean staining grades in test and control eyes respectively after each of the three rinses were (1) 2.41 ± 0.41, 2.25 ± 0.69 (p = 0.9); (2) 2.34 ± 0.79, 2.1 ± 0.83 (p = 0.8); and (3) 1.71 ± 0.65, 1.60 ± 0.79 (p = 0.6) there was no significant reduction in staining with rinsing (p > 0.05) and no difference was observed between test and control eyes at any sampling-point. Similar observations made in ex vivo rabbit eyes replicated these results.

Conclusions

Pooling or accumulation of SFL solution within intercellular spaces does not appear to contribute to the appearance of superficial micropunctate corneal staining.