Power Profiles and In Vitro Optical Quality of Scleral Contact Lenses: Effect of the Aperture and Power.

OBJECTIVE: To assess the power profile and in vitro optical quality of scleral contact lenses with different powers as a function of the optical aperture. METHODS: The mini and semiscleral contact lenses (Procornea) were measured for five powers per design. The NIMO TR-1504 (Lambda-X) was used to assess the power profile and Zernike coefficients of each contact lens. Ten measurements per lens were taken at 3- and 6-mm apertures. Furthermore, the optical quality of each lens was described in Zernike coefficients, modulation transfer function, and point spread function (PSF). A convolution of each lens PSF with an eye-chart image was also computed. RESULTS: The optical power fluctuated less than 0.5 diopters (D) along the optical zone of each lens. However, the optical power obtained for some lenses did not match with its corresponding nominal one, the maximum difference being 0.5 D. In optical quality, small differences were obtained among all lenses within the same design. Although significant differences were obtained among lenses (P<0.05), these showed small impact in the image quality of each convolution. CONCLUSIONS: Insignificant power fluctuations were obtained along the optical zone measured for each scleral lens. Additionally, the optical quality of both lenses has showed to be independent of the lens power within the same aperture.

Clinical evaluation of rigid gas permeable contact lenses and visual outcome after repaired corneal laceration.

OBJECTIVE: To evaluate the clinical value of rigid gas permeable contact lenses (RGPCLs) in patients with traumatic corneal scarring and address implications of primary corneal repair. METHODS: Eighteen subjects with a history of corneal laceration were fit with RGPCLs. Scar locations were divided into two zones; each patient was examined using Pentacam. Entering data included uncorrected visual acuity (UCVA), spectacle-corrected visual acuity (SVA), time between injury and RGPCL fitting, location and size of scar, and amount of corneal astigmatism. Follow-up data included RGPCL visual acuity (RGPCLVA), RGPCL-related complications, and dropout characteristics. Visual acuity values were converted to logMAR for analysis. RESULTS: No serious complications occurred. The average time between suture removal and RGPCL fitting was 5.7±5.5 months. Average corneal astigmatism was -3.44±2.09 diopters. One subject had developed corneal ectasia. RGPCLVA was more than 0.1 in three subjects: one experienced primary corneal repair complications, and two subjects (<10 years) developed amblyopia. In both zones, the difference in RGPCLVA outcome between zone I and zone II was not statistically significant (F=0.060, P=0.809). The difference between SVA in zones I and II was found to be statistically significant (F=6.131, P=0.026), as were the differences between SVA and RGPCLVA (F=8.598, P=0.010). The scar size had no significant influence on RGPCLVA, SVA, or UCVA. Four participants (22.2%) were successfully fit. Dropout characteristics included ocular discomfort, inconvenience, parental apprehension, and low motivation. CONCLUSIONS: Rigid gas permeable contact lens is an ideal method for evaluating visual potential in patients with traumatic corneal astigmatism. Pentacam examinations of those patients with poor RGPCLVA can help an ophthalmologist find and understand existing problems in suture techniques.

Effect of lens care systems on the clinical performance of a contact lens.

PURPOSE: To evaluate subjective responses, rates of solution-induced corneal staining (SICS), and corneal infiltrative events (CIEs) associated with a silicone hydrogel when worn under a daily disposable (DD) or daily wear (DW) modality. METHODS: Data were obtained from seven prospective clinical trials, involving 283 subjects wearing Senofilcon A contact lenses (Johnson and Johnson Vision Care, Jacksonville, FL). Four groups wore the contact lens on a DW basis using multipurpose solutions (DW-MPS, n = 160), two groups using hydrogen peroxide (DW-H2O2, n = 83), and one group as a DD (n = 40). Participants were followed for 3 months using the same protocol. Subjective ratings were compared between DD and DW groups using a linear mixed model. Rates of SICS and CIE were calculated as the percent frequency of first events within the 3-month study. Association of SICS and CIE with subjective responses was analyzed using a linear mixed model. RESULTS: End-of-day comfort and dryness ratings were significantly better for DD (8.5 ± 1.7 and 8.6 ± 1.7, respectively) compared with DW-H2O2 (7.7 ± 1.8, p = 0.01; 7.6 ± 1.9, p = 0.006, respectively) and DW-MPS (7.7 ± 1.7, p = 0.004; 7.6 ± 2.0, p = 0.003, respectively). Compared with DD, a higher incidence of CIE and SICS was found for DW-MPS (0.0 vs. 3.9%, p = 0.021; 0.9 vs. 8.6%, p = 0.002, respectively). Comfort at insertion and end of day and end-of-day dryness scores were significantly lower for participants who experienced SICS (8.2 ± 1.6, 7.0 ± 1.9, and 7.0 ± 2.2) than those who did not (8.8 ± 1.2, p = 0.004; 7.9 ± 1.7, p = 0.002; and 7.9 ± 1.8, p = 0.003, respectively). Comfort at insertion scores were significantly lower for participants who experienced CIEs than those who did not (8.2 ± 1.5 vs. 8.8 ± 1.4, p = 0.032). CONCLUSIONS: Senofilcon A clinical response is modulated by the lens care products. All lens care products tested reduced subjective responses relative to DD modality, whereas MPS increased the incidence of CIEs and SICS. Senofilcon A performs best when used on a DD basis.

Visual performance of two simultaneous vision multifocal contact lenses.

PURPOSE: To evaluate and compare the visual performance of two simultaneous vision multifocal contact lenses (CLs). METHODS: In this cross-over study design 20 presbyopic subjects were fitted with two different simultaneous vision multifocal CLs (the PureVision Multifocal Low Add and Acuvue Oasys for Presbyopia) in random order. After 1 month, binocular distance visual acuity (BDVA) under photopic (85 cd/m(2)) and mesopic (3 cd/m(2)) conditions, binocular near visual acuity (BNVA), binocular distance contrast sensitivity function (CSF) under photopic and mesopic conditions, binocular near CSF and defocus curve were measured. Subjects were then refitted with the alternative correction and the procedure was repeated. RESULTS: Mean BDVA under photopic conditions was similar for the Acuvue Oasys for Presbyopia and PureVision Multifocal Low Add: 0.01 ± 0.08 and 0.00 ± 0.08 logMAR, respectively (P = 0.45). Under mesopic conditions the values of BDVA were 0.20 ± 0.58 and 0.11 ± 0.09 logMAR, respectively (P = 0.005). Mean BNVA was 0.20 ± 0.05 and 0.15 ± 0.08 logMAR for the Acuvue Oasys and PureVision Low Add, respectively (P = 0.06). Binocular distance CSF testing revealed no statistically significant differences between lenses under photopic, mesopic or near conditions. Both lenses provided a comparable intermediate visual acuity. CONCLUSIONS: Both simultaneous vision multifocal CLs provided adequate distance visual quality under photopic and mesopic conditions, and better visual acuity was provided under mesopic conditions for the Purevision lens. Both lenses provided adequate visual performance at intermediate distance, but the near visual acuity appears to be insufficient for early presbyopes who require a moderately demanding near visual quality.

Wearing time as a measure of success of scleral lenses for patients with irregular astigmatism.

OBJECTIVES: To evaluate the visual correction and clinical performance with scleral contact lenses (CL) for the visual rehabilitation of irregular astigmatism and to report the effect of brief wearing breaks on the wearing time and success rate. METHODS: A retrospective review was performed on consecutive patients who were fitted with scleral CL because of irregular astigmatism following failure of other optical corrections. Visual acuity (VA) and wearing times were abstracted. RESULTS: The 97 consecutive identified patients (155 eyes) were divided according to the diagnosis: (1) keratoconus (105 eyes; 67.7%), (2) postpenetrating keratoplasty (PK) (28 eyes; 18.1%); (3) multiple diagnoses (22 eyes; 14.2%)-postradial keratotomy, keratoglobus, pellucid marginal degeneration, PK with aphakia, and iatrogenic ectasia. The mean follow-up was 34.9 ± 18.5 months (range, 2-71 months). There was a significant increase in best VA-scleral when compared with the previous best VA-prescleral (P<0.001). The best VA-scleral was similar in the 3 groups (P>0.5). Patients who took brief breaks every 4 to 5 continuous wearing hours had a significantly higher success rate (P<0.001) among all diagnosis groups. The success rate in wearing time in the keratoconus group was significantly higher than in the PK group (P<0.001). Twenty-six patients (27%) discontinued to wear scleral lenses. CONCLUSION: Scleral lenses can be used successfully for visual rehabilitation and management of irregular astigmatism from various causative factors. The daily wearing time was significantly improved by taking brief breaks for replenishing the CL.

Overview of contact lens postmarket surveillance in the United States: system and recent study results.

This is an overview of the US contact lens (CL) postmarket surveillance systems and surveillance study results that include silicone hydrogel CLs. As 30-night continuous wear silicone hydrogel and rigid gas-permeable (RGP) CLs were approved for use in the United States in 2001, the Food and Drug Administration (FDA) mandated large postmarket surveillance studies to assess the risk of microbial keratitis with those products when worn with the 30-night wearing schedule. Since the time of the approvals, RGP 30-night wear has been used sparingly and a shift from 30-night wear has occurred for silicone hydrogel lenses. Several silicone hydrogel lenses have been approved and most of these lenses are being prescribed for daily or flexible wear and not for 30-night wear. With daily wear and less overnight use, silicone hydrogel lenses are regularly exposed to lens care products, lens cases, and improper handling, all of which may introduce sources of microbial contamination that could trigger lens-related complications. This summary of CL postmarket surveillance system and methods gives results of FDA-mandated surveillance and of recent US studies that observed "real-world" populations for safety results outside the bounds of highly controlled prospective clinical trials.

Randomised controlled study comparing comfort-related outcomes between two rigid gas permeable (RGP) lenses with different sessile drop contact angles.

PURPOSE: To compare comfort-related outcomes when wearing rigid gas permeable (RGP) contact lenses made of two different materials and using two cleaning regimes. METHODS: In a double-masked lens material cross-over study, subjects (n = 28 who completed the study) were refitted with new lenses made from (A) Boston XO material in one eye and made from (B) ONSI-56 material in the other eye. The lenses made from materials A and B were worn on the right eye and the left eye following the pattern AB-BA-AB (or vice versa) during the first, second, and third 5 week trial periods respectively. Miraflow cleaner (1st and 2nd period) was replaced by Boston Advance cleaner in the 3rd period. Comfort-related outcomes were assessed by a numerical rating scale (NRS) after each period. Subjects rated six comfort-related factors: satisfaction, sharpness of vision, end of day comfort, maximum comfortable wearing time, maximum wearing time and foreign body feeling. Additionally we obtained subjects' preferences for type of lens and lens cleaner during an exit interview. The sessile drop method was used to measure static contact angles. RESULTS: The mean of the contact angle measured for the Boston XO material was 93.3° and for the ONSI-56 material was 75.8 °. Mean 'end of the day comfort', 'satisfaction' and 'lens feeling' scores reached statistical significance (anova periods 1, 2 and 3, p's: 0.005, 0.028, 0.046, n = 23) with marginal differences in favour of those eyes that had worn lenses made of the ONSI-56 material (differences in mean scores on a 1-10 NRS never exceeded 0.7, 0.5 and 0.2 points in periods 1, 2, 3 respectively). At the exit interview 60% of the subjects (n = 17) were not able to express a preference for wearing either of the lenses, while 29% reported some preference for lenses made of the ONSI-56 material (n = 8) and 11% for wearing lenses made of the Boston XO material (n = 3) within one or more periods. CONCLUSIONS: The differences in comfort-related outcomes between contact lenses made from two different materials, with sessile contact angles that differed by 17.5°, were small. Although some observed comfort differences reached statistical significance, none of these differences were sufficiently large to support a clinically significant difference in comfort between the two materials. We recommend that both the sessile drop and the captive bubble contact angles, measured according to current standards, are made available to practitioners.

[Functional results of contact lens correction and penetrating keratoplasty in keratoconus. Report 1. Analysis of resolution ability of the eye].

Comparative analysis of functional results of contact lens correction and penetrating keratoplasty (PKP) in keratoconus are presented. To assess resolution ability we considered visual acuity and contrast sensitivity. 117 patients (219 eyes) with stage I-IV keratoconus, wearing rigid gas-permeable contact lenses (RPCL), and 60 patients (64 eyes) after PKP were examined. In 69% patients after PKP non-corrected visual acuity (NCVA) was 0.1 or more and mean best corrected visual acuity (BCVA) was 0.63, that is similar to efficacy of contact lens correction in stage III-IV keratoconus. In 31% patients NCVA after PKP was less than 0.1 due to significant refractive arrow, visual rehabilitation of these patients required use of RPCL or refractive surgery. Contrast sensitivity in medium frequencies after PKP was almost similar to that of contact lens correction in stage III keratoconus, and in high frequencies it was close to that of stage IV.

[Possible complications of orthokeratology in myopia correction].

Clinical cases representing complications (refractive, infectious and trophic) of orthokeratologic lenses (OKL) use are described. These clinical cases show that complications of OKL use can be both similar to those of routine contact correction and caused by features of mechanism of corneal refraction change as a result of OKL wear. In our opinion efficacy and safety of this option is directly depends on the correct lens fitting, patient's compliance and regular monitoring of corneal changes.

[Functional results of contact lens correction and penetrating keratoplasty in keratoconus. Report 2. Wavefront analysis].

Comparative analysis of optic aberrations in contact lens correction and after penetrating keratoplasty (PKP) in keratoconus are presented. 117 patients (219 eyes) with stage I-IV keratoconus, wearing rigid gas-permeable contact lenses (RPCL), and 60 patients (64 eyes) after PKP were examined using OPD Scan (NIDEK, Japan) to assess aberration characteristics. Total optic aberrations and higher-order aberrations of ocular and corneal wavefront were significantly increased after PKP compared to those in patients with I-III stage keratoconus wearing RGCL. Astigmatic aberrations after surgery are increased compared to that in patients wearing RGCL regardless of keratoconus stage. Generally, according to objective aberrometry efficacy of PKP is similar to that of contact lens correction in IV stage keratoconus.

[Discussions on the supervision for the post -market contact lenses according to the principles of risk management].

The paper analyses the present situation and problems of the post -market situation of contact lenses in China. According to the principles of risk management, suggestions for improving the supervision of circulation and consumption of contact lenses were given.

Posterior corneal curvature change and recovery after 6 months of overnight orthokeratology treatment.

PURPOSE: To investigate the changes in, and recovery of, posterior corneal curvature after 6 months of overnight orthokeratology (ortho-k). METHODS: Twenty-eight healthy young adults were recruited for a 6-month period of ortho-k treatment and data from their right eyes were analyzed. The mean +/- standard deviation spherical equivalent refraction (SER) at baseline was -2.95 +/- 0.88 D. Posterior simulated keratometry (Sim K) readings were measured with a corneal topographer based on rotating Scheimpflug imaging. The three phases in the study were the 6-month treatment period (Phase I); diurnal changes over a period of 8 h immediately after lens removal at the completion of the treatment period (Phase II); and a 2-month recovery period after cessation of treatment (Phase III). Measurements were taken after lens wear overnight, and after 1 week, and 1, 2, 3 and 6 months of lens wear in Phase I. In Phase II, measurements were taken immediately, and then 2, 4 and 8 h after lens removal. In Phase III, corneal parameters were monitored 1 week, 2 weeks, 1 month and 2 months after cessation of ortho-k treatment. RESULTS: In Phase I, the posterior Sim K readings were significantly steepened after the first overnight lens wear. These significant changes were not found at other visits. In Phase II, the posterior Sim K readings were the steepest immediately after lens removal and significantly flattened 2 h after lens removal. In Phase III, all the posterior Sim K readings were similar to the baseline results. CONCLUSIONS: Steepening of the posterior cornea was only observed immediately after lens removal. It returns to its original shape within 2 h after cessation of lens wear. These changes appear to be in line with recent reports of the diurnal variation in the posterior corneal shape in non-contact lens wearers. The reduction in myopia from ortho-k treatment is therefore mainly due to a flattening of the anterior cornea.

Continuous intraocular pressure monitoring in patients with obstructive sleep apnea syndrome using a contact lens sensor.

PURPOSE: To analyse nocturnal intraocular pressure (IOP) fluctuations in patients with obstructive sleep apnea syndrome (OSAS) using a contact lens sensor (CLS) and to identify associations between the OSAS parameters determined by polysomnographic study (PSG) and IOP changes. METHOD: Prospective, observational study. Twenty participants suspected of having OSAS were recruited. During PSG study, IOP was monitored using a CLS placed in the eye of the patient. The patients were classified according to the apnea-hypopnea index (AHI) in two categories, severe (>30) or mild/moderate (<30) OSAS. We evaluated several parameters determined by the IOP curves, including nocturnal elevations (acrophase) and plateau times in acrophase (PTs) defined by mathematical and visual methods. RESULTS: The IOP curves exhibited a nocturnal acrophase followed by PTs of varying extents at which the IOP remained higher than daytime measurement with small variations. We found significant differences in the length of the PTs in patients with severe OSAS compared to those with mild/moderate disease (P = 0.032/P = 0.028). We found a positive correlation between PTs and OSAS severity measured by the total number of apneic events (r = 0.681/0.751 P = 0.004/0.001) and AHI (r = 0.674/0.710, P = 0.004/0.002). Respiratory-related arousal and oxygen saturation also were associated significantly with the IOP PT length. CONCLUSIONS: Periods of nocturnal IOP elevation lasted longer in severe OSAS patients than those with mild/moderate OSAS and correlate with the severity of the disease. The length of the nocturnal PT is also associated to respiratory parameters altered in patients with OSAS.

The COVID-19 pandemic: Important considerations for contact lens practitioners.

A novel coronavirus (CoV), the Severe Acute Respiratory Syndrome Coronavirus - 2 (SARS-CoV-2), results in the coronavirus disease 2019 (COVID-19). As information concerning the COVID-19 disease continues to evolve, patients look to their eye care practitioners for accurate eye health guidance. There is currently no evidence to suggest an increased risk of contracting COVID-19 through contact lens (CL) wear compared to spectacle lens wear and no scientific evidence that wearing standard prescription spectacles provides protection against COVID-19 or other viral transmissions. During the pandemic there will potentially be significant changes in access to local eyecare. Thus, it is imperative CL wearers are reminded of the steps they should follow to minimise their risk of complications, to reduce their need to leave isolation and seek care. Management of adverse events should be retained within optometric systems if possible, to minimise the impact on the wider healthcare service, which will be stretched. Optimal CL care behaviours should be the same as those under normal circumstances, which include appropriate hand washing (thoroughly with soap and water) and drying (with paper towels) before both CL application and removal. Daily CL cleaning and correct case care for reusable CL should be followed according to appropriate guidelines, and CL exposure to water must be avoided. Where the availability of local clinical care is restricted, practitioners could consider advising patients to reduce or eliminate sleeping in their CL (where patients have the appropriate knowledge about correct daily care and access to suitable lens-care products) or consider the option of moving patients to daily disposable lenses (where patients have appropriate lens supplies available). Patients should also avoid touching their face, including their eyes, nose and mouth, with unwashed hands and avoid CL wear altogether if unwell (particularly with any cold or flu-like symptoms).

The Need for Ocular Protection for Health Care Workers During SARS-CoV-2 Outbreak and a Hypothesis for a Potential Personal Protective Equipment.

SARS-CoV-2 is a coronavirus with high infectivity and has caused dramatic pressure on health systems all over the world. Appropriate personal protection for medical staffs is critical. For ocular protection, there is ongoing hot debate and concern for potential ocular transmission of SARS-CoV-2. Ocular manifestations and positive detection of viral RNA in ocular samples were only reported in very small number of patients infected with SARS-CoV-2. However, health care workers need to face patients more closely and have higher risk of aerosol contamination. Thus, appropriate ocular protection for medical workers is still recommended by organizations such as WHO and American Academy of Ophthalmology. Although eye goggles provide excellent protection and are mandatory for medical practitioners with high risk of exposure, they are not ideal for common clinical practice, because they can disturb vision due to extensive formation of water droplets and frequently cause moderate to severe discomfort after longtime wearing, which have been reported to interfere with working status. For the majority of medical workers who don't deal with high risk patients, they are not advised to wear goggles in daily practice. However, they also face the risk of infection due to the presence of asymptomatic carriers. Especially in situations with high risk of ocular exposure, such as close physical examination, eye surgery, dental clinics and surgery, ocular protection may be needed. Griffithsin has been shown to directly bind to spike proteins and has anti-viral activity against a broad spectrum of viruses, including coronavirus. Griffithsin is found to inhibit the entry of SARS-CoV at relatively low concentration and is stable and non-toxic. SARS-CoV-2 and SARS-CoV share the same entry receptors and their spike proteins are similar in conformation. We hypothesize that contact lenses containing nanoparticles loaded with griffithsin may provide sufficient ocular protection for medical staffs without high risk of exposure during the outbreak period of SARS-CoV-2. If proven effective, griffithsin-loaded contact lens can be considered as a supplementary ocular protective equipment for medical workers who can tolerate well. The daily disposable contact lens should be applied as needed and refrain from extended wearing in order to reduce potential side effects.

Ocular Drug Delivery Systems Using Contact Lenses.

The use of contact lenses as ocular drug delivery systems has been considered intuitive for decades. However, at this time, there are no approved products using such systems. In this article, we review the challenges with current therapies, pharmacokinetics, and pharmacodynamics of different drug classes and the patient population. In addition, we note the relative lack of clinical studies, and list potential products in active development at this time. In particular, we address the alignment of time course of the therapeutic need, the pharmacokinetics of the molecule, and the delivery characteristics of the systems (e.g., pulsatile vs. zero-order). We also discuss the needs of various populations including the elderly (who may have motor and cognitive issues as well as presbyopia) and the young. While a contact lens delivery system may also provide refractive correction, to date, most of the studies have used noncorrective (plano) lenses. We also considered nanotechnology-based carrier systems. We generalize the development of contact lens delivery systems to all ocular delivery systems in which there are relatively few product approvals and long development times.

Scleral contact lens thickness profiles: The relationship between average and centre lens thickness.

PURPOSE: To develop a methodology to reliably determine the thickness profile of scleral contact lenses and examine the relationship between the centre and average lens thickness for a range of lens designs and back vertex powers. METHODS: High-resolution images of 37 scleral trial lenses (Epicon LC, Rose K2 XL and ICD 16.5) were captured using an optical coherence tomographer, and their thickness profiles were generated after correcting for known measurement artefacts. Centre lens thickness values were compared with manual lens gauge measurements, and repeatability was assessed by comparing average thickness values derived from orthogonal meridians of each lens. RESULTS: The imaging technique displayed a high level of agreement with a manual lens gauge for centre thickness measurements; mean difference 5 ±â€¯9 µm (95% LoA -14 to +23 µm), and a very high level of repeatability; mean difference between orthogonal meridians 1 ±â€¯3 µm (95% LoA -6 to +8 µm). Lens thickness profiles varied between lens designs, with distance from the lens centre, and with back vertex power. Increasing back vertex powers resulted in a significant over or underestimation (up to 33% for high minus powers) of the average lens thickness based on the centre lens thickness. CONCLUSIONS: The thickness of scleral contact lenses varies with distance from the lens centre and the back vertex power. The average lens thickness value derived from the entire lens provides a more appropriate representation of the true lens thickness and should be used in the calculation of scleral lens oxygen transmissibility.

Imaging protein deposits on contact lens materials.

PURPOSE: The majority of studies investigating protein deposition on contact lens materials require that the deposit of interest be removed, potentially resulting in erroneous results if some proteins are not removed adequately. The purpose of this study was to investigate the use of in situ imaging methods to examine protein deposition on conventional poly(2-hydroxyethyl methacrylate) (polyHEMA)-based and silicone hydrogel contact lens materials. METHODS: Six silicone hydrogel and five polyHEMA-based hydrogel contact lens materials were examined by Atomic Force Microscopy (AFM) and/or Scanning Electron Microscopy (SEM) techniques, after being deposited with proteins in an in vitro model. AFM studies examined lenses deposited solely with lysozyme at approximate physiological concentrations and SEM studies were conducted on lenses exposed to a dilute mixture of lysozyme and albumin-conjugated gold spheres. RESULTS: AFM studies demonstrated that the lens materials had markedly differing surface topographies. SEM results showed that galyfilcon A and balafilcon A lenses deposited both lysozyme and albumin in relatively large aggregates, as compared with lotrafilcon A and B, in which the proteins were deposited in a more evenly spread, monolayer formation. Polymacon lenses deposited more protein than any of the silicone hydrogel materials and much of the protein was aggregated together. AFM data indicated that balafilcon A, lotrafilcon A and polymacon deposited lysozyme in a similar manner, with very little lysozyme being deposited in discrete areas. Galyfilcon A behaved very differently, with the lysozyme exhibiting both aggregates as well as string-like formations over the lens surface. CONCLUSIONS: Imaging techniques that allow proteins to be examined in situ show much promise for determining the extent and physical characterization of protein on contact lens materials. These techniques indicate that the pattern of deposition of proteins onto silicone hydrogel contact lens materials differs between materials, depending upon their bulk and surface composition.