Highlights
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The conventional approach is to adapt new contact lens wearers by ‘building-up’ wearing time.
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There is no underpinning scientific evidence for the need for this approach with modern soft contact lenses.
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Fast versus gradual adaptation in new daily disposable hydrogel & silicon-hydrogel contact lens wearers were investigated.
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No statistically or clinically significant differences were demonstrated between the adaptation schedules or lens materials.
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The study demonstrated there is no need to recommend an adaptation schedule with modern daily disposable contact lenses.
Abstract
Purpose
Despite the widespread practice of gradually adapting all new soft contact lens wearers (neophytes), there is little evidence-based research underpinning such practice. This work determined if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone-hydrogel daily disposable contact lenses.
Method
At four sites, neophytes (19–32 years) were randomly assigned to an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear-time by 2 h on each subsequent day until they had reached 10 h) with hydrogel (n = 24 fast; n = 21 gradual) or silicone-hydrogel (n = 10 fast; n = 10 gradual) contact lenses. Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT). A range of subjective scores (using 0–100 visual analogue scales) were recorded at the initial visit and after 10 h of lens wear, 4–6 days and 12–14 days after initial fitting. Subjective scores were also repeated after 7 days.
Results
There was no difference (p > 0.05) in ocular surface physiology between the fast and gradual adaptation groups at any time point in either lens type. NIBUT was similar at all time points for both adaptation groups in both lens types with the exception that the gradual adaptation silicone-hydrogel wearers had a slightly longer NIBUT (p = 0.007) than the fast adaptation group at 12-14 days. Subjective scores were also similar across the visits and lens types with the exception of ‘lens awareness’ and ‘ease of lens removal’ which were better (p < 0.05) in the fast compared with the gradual adaptation hydrogel lens group at day 7. Additionally, ‘end-of-day discomfort’ was better (p = 0.02) in the fast compared with the gradual adaptation hydrogel lens group at 12–14 days.
Conclusion
There appears to be no benefit in daily disposable soft contact lens adaptation for neophytes with modern contact lens materials.
1
Introduction
Currently, most eye care practitioners (ECPs) commonly recommend that all new contact lens wearers (neophytes) should be ‘eased’ into lens wear in an attempt to maximise the clinical performance of their lenses over the first few days of wear [ ]. The practice of constraining these initial wear times has been advocated by various authors in many of the key texts still used to train new ECPs ( Table 1 ) [ ]. Typical proposed wear schedules vary from 2 to 4 hours on the first day followed by incremental increases of 1–2 hours daily until a maximum recommended wear time is achieved. A recent web-based survey of 186 ECPs from 26 countries gathered data on how silicone-hydrogel (daily disposable and re-useable) lenses were prescribed over the first week of wear [ ] and found that there was no significant difference in how these two modalities were managed and that the majority of respondents advised wearing the lenses for 2–4 hours on the first day and gradually building-up to ‘as long as comfortable’ by the end of the first week.
| Book | Recommendations on initial adaptation |
|---|---|
| Contact Lens Practice Fetcher, Lupelli and Rossi (1994) [ ] |
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| Manual of Contact Lens Prescribing and Fitting Hom and Bruce (1997) [ ] |
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| Fitting Guide For Rigid And Soft Contact Lenses Stein et al (2002) [ ] |
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| Clinical Contact Lens Practice Bennett and Weissman (2005) [ ] |
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| The Contact Lens Manual Gasson and Morris (2010) [ ] |
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| Contact Lens Practice Efron (2018) [ ] |
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| Contact Lenses Phillips and Speedwell (2019) [ ] |
|
Despite the widespread use and clinical acceptance of gradually adapting new lens wearers, there is remarkably little evidence-based research underpinning such practice, which instead seems to be based on clinical intuition. The underlying rationale appears to be based upon conventional wisdom, that a gradual increase in wear time allows the patient a period of acclimatisation with respect to comfort, vision and ocular physiology [ ]. These first few days are crucial to the long-term success of a new wearer and there is no doubt that they must be carefully managed in order to avoid drop-out,[12.13] the most common reasons for which are discomfort, visual and handling problems [ ].
Gradual adaptation is thought to be particularly important in high modulus rigid lens wear [ ], in order to allow a patient to become accustomed to the physical presence of the lens on-eye. However, soft lenses are significantly more comfortable than their rigid counterparts, which is thought to be due to the reduced interaction with the upper eyelid and a lower modulus [ ]. In the past, soft lenses were manufactured from materials with low oxygen permeability, such as polyhydroxyethyl methacrylate [ ], which often resulted in hypoxia-related complications such as limbal hyperaemia, corneal epithelial microcysts and corneal stromal oedema. Longer-term effects such as thinning of the corneal epithelium, corneal endothelial polymegethism and stromal thinning have also been well documented [ , ]. It remains unclear, however, whether a gradual adaptation in the first weeks of wear with these lenses had any significant impact on the ocular physiology response.
Contemporary soft contact lenses have seen significant improvements compared to their predecessors in areas such as material biocompatibility (e.g. improved oxygen performance with silicone-hydrogel lenses), manufacturing quality and lens design, yet the practice of prescribing a gradual initial adaptation period persists. These lenses are associated with a lower incidence of adverse physiological reactions such as limbal and conjunctival redness [ , ], and corneal swelling [ ], when compared to traditional hydrogels. With more and more lens wearers opting for the convenience of daily disposable lenses and many only wishing to wear them on an occasional basis, the notion of a gradual adaptation period may seem antiquated and conservative to many practitioners. Nevertheless, the increased risk of infiltrates in silicone-hydrogel daily wear remains a significant drawback [ , ], being twice as common as with hydrogel materials [ ]. It is unknown if the clinical requirements for any adaptation period differ with material type.
If the lack of a gradual adaptation phase was shown to be safe by any reasonable definition of the term and to have no effect on ocular comfort, it would hold several advantages over a more gradual approach, such as: better patient compliance due to increased simplicity; less impact on the personal/work commitments of the wearer as a result of not needing to remove lenses part-way through the day; and to allow wearers who wish to wear their lenses infrequently to do so for a full day from the start. Therefore, this work set out to investigate if there were differences in ocular surface physiology and subjective performance in contemporary daily disposable lens wearers subjected to a fast, versus a gradual, adaptation approach in the first few days of lens wear. The work also investigated if there were differences between these approaches for silicone-hydrogel and hydrogel contact lens wearers.
2
Methods
2.1
Study lenses
The two daily disposable lens types investigated in this work were the 1-DAY ACUVUE® MOIST and the ACUVUE® OASYS 1-DAY with HydraLuxe™ (Johnson & Johnson Vision) and are outlined in Table 2 . The lenses were chosen as representative examples of contemporary, commonly prescribed hydrogel and silicone-hydrogel lenses. Both had a similar design (i.e. edge shape and overall thickness profile) and the daily disposable modality was chosen, as it is the predominant modality consumer choice as well as mitigating any interactions from accompanying lens care solutions systems.
| Lens Name | 1-DAY ACUVUE® MOIST | ACUVUE® OASYS 1-DAY with HydraLuxe™ |
|---|---|---|
| Manufacturer | Johnson & Johnson Vision | Johnson & Johnson Vision |
| Material | Etafilcon A | Senofilcon A |
| Oxygen permeability (ISO units) | 21 | 77 |
| Back optic zone radius (BOZR) (mm) | 8.5, 9.0 | 8.5, 9.0 |
| Total diameter (mm) | 14.2 | 14.3 |
| Equilibrium water content (%) | 58 | 38 |
| Back vertex power (BVP) (D) | +6.00 to -12.00 | +8.00 to -12.00 |
Subjects were fitted with one of the two lens types for a period of 12–14 days.
2.2
Study design
This was a prospective, parallel group, randomised, investigator-masked, multi-site clinical investigation which was carried out at four academic institutions: Aston University (Birmingham, UK), Cardiff University (Cardiff, UK), Glasgow Caledonian University (Glasgow, UK) and the Technological University Dublin (Dublin, Ireland). All four institutions were given a favourable ethical opinion by their respective university research ethics committee. The study conformed to the tenets of the Declaration of Helsinki and all subjects provided written informed consent prior to enrolment. Inclusion criteria included being aged between 18 and 40 years, having astigmatism ≤0.75D, having healthy eyes and an ability to understand and full comply with the study procedures. Potential subjects were excluded if they were previous or current contact lens wearers, had previous eye surgery, had an ocular or systemic condition or were on medication that could contraindicate contact lens wear, they had known hypersensitivity to saline or fluorescein, or they were pregnant or breast-feeding.
In order to determine the overall sample size, power analysis was undertaken. A sample size of 8 subjects in each adaptation/lens material group would give 80% power to detect a difference of 0.5 or more in Efron grading units in hyperaemia, based on a standard deviation of 0.2 grading units [ ] and an alpha of 0.05 for a Mann-Whitney U test (G*Power). A sample size of 10 subjects in each adaptation / lens material group would have 80% power to detect a difference of at least 10 on a 100 point scale for subjective comfort scores using visual analogue scales, based on a standard deviation of 8–10 grading units [ , ] and an alpha of 0.05 for a Mann-Whitney U test (G*Power).
The 65 subjects attended three visits in total. At the initial visit, various clinical (baseline) investigations were performed. These included refraction, visual acuity and slit lamp biomicroscopy of the ocular surface; bulbar, limbal and palpebral conjunctival hyperaemia were graded to the nearest 0.1 unit using Efron 0–4 unit grading scales [ ] (white light and 16X magnification). Following application of sodium fluorescein (1.5 mg impregnated strips), corneal staining and palpebral redness and roughness were graded using the same grading scales. Non-invasive tear film breakup time (NIBUT) was assessed using the Tearscope Plus (Keeler, Windsor, UK) or keratometer mires (Bausch and Lomb, Rochester, NY, USA) prior to lid eversion and the average of three measurements were recorded for each eye.
Eligible subjects were assigned to one of the two lens types ( Table 2 ), based on site (each site only fitted one lens type) and lens fit was assessed according to the criteria of Boychev et al. [ ] After successful lens fitting, subjects were randomly assigned to one of the following two adaptation schedules: i) no build-up of wearing time (fast adaptation) where subjects wore lenses for 10 h from the first day or ii) a more gradual build-up (gradual adaptation) where subjects wore lenses for 4 h on the first day and increased their wear time by 2 h on each subsequent day until they had reached 10 h. The investigator was masked to the subject’s adaptation schedule. All subjects were carefully instructed on lens application and removal and given full information on how to care for their lenses as well as how to comply with their assigned wearing schedule.
Subjective scores were collected using visual analogue scales (0–100 where 0 indicated “very uncomfortable” and 100 “very comfortable”) for comfort before lens application, comfort after lens application and overall clarity of vision.
Subjects were asked to return, once the lenses had been in-situ for 10 h, for two further follow-up visits, one after 4–6 and the other 12–14 days from the initial visit. Similar slit lamp biomicroscopy and TBUT investigations were undertaken at all visits. The same subjective scores were collected as at the initial visit but additionally ‘lens awareness’ (anchored by “very aware of lenses” to “completely unaware of lenses”), ‘end-of-day comfort’, ‘ease of lens application’ (anchored by “very difficult to handle” to “very easy to handle”) and ‘ease of lens removal’ (anchored by “very difficult to remove” to “very easy to remove”) were recorded using 0–100 visual analogue scales. The subjective visual analogue scales were also repeated after 7 days of lens wear by paper form returned at the final visit.
2.3
Statistical analysis
Statistical analyses were performed using IBM SPSS Statistics (v23 IBM Corp. Chicago, Illinois, USA). The data were not found to be normally distributed (Kolmogorov-Smirnov Test p < 0.05) therefore Mann-Whitney U tests were used to investigate the differences between the gradual and fast adaptation groups at each visit. The statistical significance level was set at p < 0.05.
3
Results
The demographics of the study groups are shown in Table 3 . All recruited subjects completed the study and no adverse events occurred. The lenses adequately fitted all subjects.
