Contact lens complications among wearers in Ghana

PurposeContact lens (CL) practice is relatively new in Ghana; a country where the geographical location (warm climate) lends itself to harsh environmental conditions (high humidity) known to influence CL wear. Recent studies suggest an increase in CL wear (corrective and cosmetic), yet, there are no studies about CL-related complications. This study sought to determine the complications associated with CL wear in Ghana.MethodsThis was a retrospective cohort study. The medical records of contact lens wearers from five CL clinics in the two largest metropolises in Ghana, Accra and Kumasi, were reviewed. Included in the study were records of individuals who visited the clinics within the period of 2013–2016. Data on patients with contact lens-related complications were analyzed.ResultsThe prevalence of CL complications was 29.06 %. The mean ± SD age of patients with CL complications was 35 ± 15 years. Contact lens complications were more common in females (52.90 %). The majority of complications were in soft contact lens wearers (82.35 %). Refractive error correction was the most common indication for CL wear (61.76 %) among those with complications, followed by keratoconus (14.71 %), scarred blind eye (14.71 %), corneal ulcer (5.88 %) and anterior staphyloma (2.94 %). Contact lens complications reported were giant papillary conjunctivitis (41.18 %), corneal infiltrates (23.53 %), bacterial keratitis (14.71 %), corneal abrasion (11.76 %), dry eye (5.88 %) and corneal oedema (2.94 %). The causes of CL complication were inappropriate lens cleaning (29.41 %), poor hygiene (23.53 %), overnight contact lens wear (17.64 %), poor lens fit (14.71 %) and reaction to contact lens solution (14.71 %).ConclusionContact lens complications were more common in soft contact lens wearers in Ghana. Giant papillary conjunctivitis was the most common contact lens complication reported. Adherence to CL wear care regimen and good personal hygiene may prevent the majority of CL complications observed in Ghana.     

Non-invasive objective and contemporary methods for measuring ocular surface inflammation in soft contact lens wearers – A review

Contact lens wear is one of the primary risk factors for the development of ocular surface inflammatory events. The purpose of this review is to examine and summarize existing knowledge on the mechanisms of contact lens related ocular surface inflammation and the evidence for the effectiveness of current objective methods to measure ocular surface inflammation. Contact lens wear is postulated to trigger an inflammatory response on the ocular surface due to mechanical, chemical, hypoxic stress, or by the introduction of microbes and their toxins. Apart from the traditional signs of inflammation, such as swelling, oedema, redness and heat, on the ocular surface, other methods to measure ocular surface inflammation in sub-clinical levels include tear inflammatory mediator concentrations, conjunctival cell morphology, and corneal epithelial dendritic cell density and morphology. Tear inflammatory mediator concentrations are up- or down-regulated during contact lens wear, with or without the presence of associated inflammatory events. There is higher conjunctival cell metaplasia observed with contact lens wear, but changes in goblet cell density are inconclusive. Dendritic cell density is seen to increase soon after initiating soft contact lens wear. The long term effects of contact lens wear on dendritic cell migration in the cornea and conjunctiva, including the lid wiper area, require further investigation. Currently patient factors, such as age, smoking, systemic diseases and genetic profile are being studied. A better understanding of these mechanisms may facilitate the development of new management options and strategies to minimize ocular surface inflammation related to contact lens wear.     

Improving ocular surface comfort in contact lens wearers

PurposeContact lens discomfort (CLD) is a major concern that can lead to the decreased or abandoned use of contact lenses. Contact lens users with dry eye disease are more likely to present with CLD. This study was conducted to evaluate the efficacy of a bioprotective preservative free, hypotonic, 0.15% hyaluronic acid (HA)-3% Trehalose artificial tear in managing dry eye symptoms in contact lens wearers.MethodsA prospective, single-arm, observational pilot study to evaluate the effectiveness of treatment with HA-Trehalose artificial tears in contact lens wearers (N = 33) aged 18–45 years with symptoms of ocular discomfort. Participants used a preservative-free, hypotonic HA-Trehalose artificial tear (1 drop/4 times per day) for 84 days. Participants were assessed using Visual Analogue Scale (VAS) for dry eye symptoms (pain, photophobia, dry eye sensation, blurry vision, foreign body sensation, itching, tingling/burning, and sticky eye feeling), Ocular Surface Disease Index (OSDI), Contact Lens Dry Eye questionnaire (CLDEQ-8), Berkley Dry Eye Flow-Chart (DEFC) on Day 0 and Day 84 and tear break-up time (TBUT), ocular surface staining with fluorescein and lissamine green, tear meniscus evaluation, and visual acuity on Day 0, 35, and 84.ResultsAll VAS symptoms (except tingling/burning and sticky eye feeling), OSDI, CLEDQ-8, and DEFC showed statistically significant (p < 0.05) improvement from baseline (Day 0) to Day 84. Similarly, corneal (fluorescein) and conjunctival (lissamine green) quality improved during the study (p < 0.05 at Day 84 versus baseline). Tear break-up time (TBUT), conjunctival (lissamine green) staining, and tear meniscus decreased but the changes were not statistically significant. Visual acuity did not change during the study. There were no ocular or systemic adverse events.ConclusionsThis study showed that the instillation of a preservative-free, hypotonic, HA-Trehalose artificial tear in contact lenses wearers with dry eye syndrome significantly improved symptoms and reduced associated signs such as corneal and conjunctival staining.     

BCLA CLEAR - Effect of contact lens materials and designs on the anatomy and physiology of the eye

This paper outlines changes to the ocular surface caused by contact lenses and their degree of clinical significance. Substantial research and development to improve oxygen permeability of rigid and soft contact lenses has meant that in many countries the issues caused by hypoxia to the ocular surface have largely been negated. The ability of contact lenses to change the axial growth characteristics of the globe is being utilised to help reduce the myopia pandemic and several studies and meta-analyses have shown that wearing orthokeratology lenses or soft multifocal contact lenses can reduce axial length growth (and hence myopia).However, effects on blinking, ptosis, the function of Meibomian glands, fluorescein and lissamine green staining of the conjunctiva and cornea, production of lid-parallel conjunctival folds and lid wiper epitheliopathy have received less research attention. Contact lens wear produces a subclinical inflammatory response manifested by increases in the number of dendritiform cells in the conjunctiva, cornea and limbus. Papillary conjunctivitis is also a complication of all types of contact lenses. Changes to wear schedule (daily disposable from overnight wear) or lens materials (hydrogel from SiHy) can reduce papillary conjunctivitis, but the effect of such changes on dendritic cell migration needs further study. These changes may be associated with decreased comfort but confirmatory studies are needed. Contact lenses can affect the sensitivity of the ocular surface to mechanical stimulation, but whether these changes affect comfort requires further investigation.In conclusion, there have been changes to lens materials, design and wear schedules over the past 20+ years that have improved their safety and seen the development of lenses that can reduce the myopia development. However, several changes to the ocular surface still occur and warrant further research effort in order to optimise the lens wearing experience.     

Ocular complications of soft contact lens wearers in a tertiary eye care centre of Nepal

AimTo determine the prevalence and the major types of ocular complications related with soft contact lenses (CL) in a tertiary eye care centre of Nepal.MethodsMedical files of 4064 soft CL wearers who started wearing CL between January 2003 and December 2010 in BP Koirala Lions Centre for Ophthalmic Studies (BPKLCOS) Kathmandu, Nepal, were retrospectively reviewed. Records of patients who visited the hospital with complications were analyzed. Patients with ocular complications non-related with CL wear were excluded.ResultsComplications were found in 4.9% of the total soft CL wearers. Contact lens induced papillary conjunctivitis (CLPC) was the most common complication, comprising 36.9% of the total patients with complications. The other commonly found complications were superior punctuate keratitis (SPK) in 16.2%, conjunctivitis in 18.2%, meibomian gland dysfunction (MGD) in 8.6%, contact lens induced peripheral ulcer (CLPU) in 4%, corneal vascularization in 3.5% and microbial keratitis in 3%. The average time of first occurrence of complications after starting of contact lens wear was 14.3 ± 11.4 months.ConclusionCLPC, conjunctivitis and SPK were the most common types of soft CL related complications found in Nepal. Vision threatening complications like microbial keratitis was also found in some patients. Patient education in CL hygiene, after care schedule and frequent follow up examinations may help to minimize CL related complications.     

Efficacy of continuous wear PureVision contact lenses for therapeutic use.

PURPOSE: To evaluate the Bausch and Lomb PureVision contact lens as continuous wear contact lens for therapeutic and medical indications in a prospective open-ended non-randomized trial. METHODS: Patients who required therapeutic contact lens wear for various indications such as pain relief, corneal protection, persistent epithelial defects, corneal perforation and chemical burns were fitted with PureVision continuous wear contact lenses (balafilcon A, 36% water content). Success or failure of specific treatment indication was assessed in each case with evaluation of ocular and lens related complications. RESULTS: 30 eyes of 28 patients were fitted with PureVision continuous wear contact lenses. A successful fit was seen in 27 of 30 eyes with therapeutic success in 26 of 30 eyes. However, all patients reported symptomatic relief. Duration of lens use ranged from 3 days to 3 months. Dry eye was the most frequent cause of contact lens associated therapeutic failure. Complications included lens loss (two eyes), tight lens (one eye) and infective keratitis (two eyes). CONCLUSIONS: PureVision contact lenses were found to be safe and efficacious for continuous wear therapeutic use to a maximum of 90 days. The contact lens was also easier to handle by virtue of its resilient nature. There were no significant corneal complications of hypoxia, i.e. corneal oedema. Lens losses and deposits were minimal. The lens performance and fitting characteristics compares favorably with previous therapeutic lenses used by the investigators. This new lens may be considered as a safe and effective alternative for use as bandage contact lens.     

Current concepts: contact lens related Pseudomonas keratitis.

Despite the development of silicone hydrogel lenses, Pseudomonas aeruginosa (PA) continues to be the leading cause of contact lens related microbial keratitis. Understanding the pathogenesis of PA-mediated corneal infection is critical to the development of new prevention and treatment strategies. Recently intracellular invasion of surface corneal epithelial cells by PA has been revisited as an important element in the infection process. This review identifies the mechanisms involved, and examines the roles of the lens, hypoxia alone, PA stain, cystic fibrosis transmembrane receptor protein (CFTR), and membrane lipid rafts in mediating intracellular invasion in both in vitro and in vivo conditions. Non-toxic blockade of raft formation in vitro or in vivo effectively abrogates PA internalization and may represent a unique, new strategy to prevent or ameliorate lens-related PA microbial keratitis.     

Corneal erosions in contact lens wear

Contact lens wear continues to be the highest single risk factor for microbial keratitis, particularly when worn in the extended wear modality. For microbial keratitis to occur, the presence of at least a bacterial load as well as a break in the corneal surface is required. One such break occurs in the case of a corneal erosion. These well-circumscribed areas of full thickness epithelial loss can occur both with and without contact lens wear, however the risk of infection is greater in the presence of a lens due to its capacity to provide a vector for the entry of bacterial pathogens. While erosions in non-contact lens wearers are thought to result from defective epithelial basement membrane anchoring, the underlying causes during contact lens wear are yet unknown. This article sets out to review corneal erosions associated with contact lens wear, their associated risk factors such as extended wear, the mechanisms that may be responsible for their formation and the factors that differentiate them from other contact lens related adverse events. Appropriate diagnosis and understanding of the relevant pathophysiology is important to the effective treatment and an understanding of the aetiological factors responsible for erosions is critical to the development of preventative strategies and effective clinical care.     

Presbyopia and the aging eye: Existing refractive approaches and their potential impact on dry eye signs and symptoms

Every part of the human body is subject to aging, including the eye. An increased prevalence of dry eye disease with age is widely acknowledged. Aging threatens ocular surface homeostasis, altering the normal functioning of the lacrimal functional unit and potentially leading to signs and symptoms of dry eye. Additional age-related processes take place within the crystalline lens, leading to presbyopia and cataractogenesis. Correction strategies for presbyopia and cataracts may directly or indirectly challenge the ocular surface. Contact lenses disturb the normal structure of the tear film and can interact negatively with the ocular surface, further deteriorating an already unbalanced tear film in presbyopes, however, newer contact lens designs can overcome some of these issues. Moreover, cataract and corneal refractive surgeries sever corneal nerves and disrupt the corneal epithelium and ocular surface, which can influence surgical outcomes and aggravate dryness symptoms in older age groups. This review summarises the current understanding of how the invasive nature of contact lens wear and cataract and refractive surgery influence signs and symptoms of ocular dryness in an aging population.     

Acanthamoeba keratitis associated with misuse of daily disposable contact lenses.

PURPOSE: To report a case of Acanthamoeba keratitis that occurred in a daily disposable contact lens wearer. METHOD: Case report. RESULTS: A 70-year-old gentleman presented to eye casualty with a red left eye with reduced vision and corneal epithelial changes. Acanthamoeba keratitis was not suspected initially as he was a daily disposable contact lens wearer. This led to a delay of 17 days in initiating treatment. He responded well to topical polyhexamethylene biguanide and propamidine and made a full recovery. CONCLUSION: Acanthamoeba keratitis can occur in patients who reuse daily disposable contact lenses. A diagnosis of Acanthamoeba keratitis can be difficult to make and should be considered in all patients who wear contact lenses, including daily disposable lenses. All patients who wear daily disposable contact lenses should be reminded that the benefits of this modality of contact lens are only possible if the lenses are worn once and thrown away.     

Hypersensitivity responses and contact lens wear.

Hypersensitivity diseases that involve the eye are common reasons why patients present to eyecare practitioners. Common ocular hypersensitivity disorders include allergic conjunctivitis, giant or contact lens induced papillary conjunctivitis and atopic keratoconjunctivitis. The diagnosis and management of ocular hypersensitivity can present a challenge to eyecare practitioners and an understanding of the mechanisms that underlie the signs and symptoms of such conditions is necessary for their appropriate management. This article reviews the mechanisms by which the eye responds to antigenic challenges, the pathogenesis of ocular hypersensitivity responses, particularly in relation to contact lens wear, and illustrates possible management strategies.     

Exploring the links between contact lens comfort,osmolarity and lid wiper staining

Purpose

Contact lens discomfort remains poorly understood, not least due to lack of associations between clinical signs and symptoms. This study aimed to explore the relationships between osmolarity, comfort and lid wiper epitheliopathy in contact lens wear.

Randomized crossover trial of silicone hydrogel contact lenses

PurposeThe aim of the current study is to assess, using new technologies, the interaction of four monthly silicone hydrogel contact lenses on the ocular surface and the comfort over 15 days of use.MethodsProspective cross-over, randomized and double-masked study including four materials (lotrafilcon-B, samfilcon-A , comfilcon-A and filcom-V3). Clinical examination was performed in the following order: tear meniscus height, first break-up of the tear film, the average time of all tear film breakup incidents, bulbar redness, limbal redness (Keratograph 5M ,Oculus, Germany); central corneal thickness (Pentacam, Oculus, Germany), thermography values (FLIR A325; FLIR Systems Inc., USA), and slit-lamp evaluations, including ocular surface staining. Finally, subjective comfort was obtained from Contact Lens Dry Eye Questionnaire-8.ResultsThe impact of contact lens wear on the ocular surface didn’t show statistically significant changes over time except for corneal and conjunctival staining grades on day 15 compared to day 1 for the comfilcon A group (P = .003 and P = .01, respectively). Contact lens stability and impact on the ocular surface during contact lens wear didn’t show statistically significant changes over time except in the case of the comfilcon A material with respect to the irritation item (P = .01).ConclusionsThese results suggest that the impact of monthly silicone hydrogel contact lens materials on the ocular surface after and during contact lens wear, contact lens stability over time, and subjective comfort did not reveal any significant changes over 15 days of use for any of the materials.     

Ten years of disposable contact lenses - a review of benefits and risks

The performance and benefits as well as the risks and complications of disposable soft lenses (single use disposable or re-used 2-4 weeks) are reviewed in relation to corneal physiology. Modern designs and advanced technology have resulted in disposable lenses providing excellent visual performance. Fewer subjective symptoms (e.g. dryness and grittiness), slit-lamp findings (such as injection and tarsal abnormalities), and inflammatory responses (papillary conjunctivitis; contact lens-induced acute red eye) have been reported with disposable lenses than with conventional soft lenses. The risk of contact lens-induced keratitis (CLIK) has been reported to be higher for daily wear of disposable lenses than for other lens types by UK investigators. Other studies have shown the risk of CLIK with disposable lenses to be equal to that with conventional soft lenses, and in two extensive Swedish studies, the incidence of severe keratitis was found to be significantly lower for daily wear (DW) of disposable lenses than for DW of conventional soft and rigid gas permeable lenses. Both the total complication rate and the number of unscheduled visits are found to be significantly lower for disposable lenses than for conventional soft lenses in several studies. Comfort has been reported to be significantly better and overall satisfaction significantly greater with disposable lenses than with conventional soft lenses according to many studies. These may be important reasons why the success rate for disposable lens wear is reported to be fairly high, generally 70-90%. The importance of appropriate care for 're-usable disposable lenses' must be stressed. One day disposable lenses, if used as directed, will eliminate the risk factors of inadequate cleaning and disinfection as well as contaminated lens cases.     

Contact lens wear and diabetes mellitus.

An estimated 30,000 diabetic patients in the United Kingdom currently wear contact lenses. Anecdotal clinical experience indicates that such patients have an increased risk of developing potentially sight-threatening ocular complications such as ulcerative keratitis. The corneal complications associated with diabetes, for example structural changes in the epithelial and endothelial cells, have led to some controversy regarding the suitability of contact lenses for diabetic patients. There have been few published studies documenting the ocular response of the diabetic eye to current generation contact lens materials. The purpose of this paper is to review the anterior eye manifestations of diabetes and to discuss how such changes could influence contact lens wear.     

The time course and nature of corneal oedema during sealed miniscleral contact lens wear

PurposeTo examine the magnitude and time course of central epithelial, stromal and total corneal thickness changes during sealed miniscleral contact lens wear and the influence of initial central corneal clearance upon these thickness changes.MethodsHigh-resolution OCT images were captured over an 8 h period of miniscleral contact lens wear (using a rotationally symmetric 16.5 mm diameter lens) in 15 young, healthy participants with normal corneae. Corneal thickness data were derived from OCT images using semi-automated image processing techniques over the central 4 mm.ResultsChanges in stromal and total corneal thickness followed a similar pattern throughout lens wear with oedema first detected 15 min after lens insertion (0.47 ± 0.09% increase in stromal and total corneal thickness, both p < 0.01) which peaked after 90 min of lens wear (1.36 ± 0.24% increase in stromal and 1.18 ± 0.20% increase in total corneal thickness, both p < 0.01) and gradually decreased thereafter. Epithelial thickness increased slightly during the first 30 min of lens wear (0.56 ± 0.30% increase, p > 0.05), then rapidly decreased reaching a minimum thickness 480 min after lens insertion (2.38 ± 0.70% decrease, p < 0.05). The maximum total corneal oedema, maximum stromal oedema, and maximum epithelial thinning were not associated with the initial central corneal clearance or the extent of lens settling over the 8 h period (all p > 0.05). Greater initial central corneal clearance resulted in less oxygen concentration reaching the cornea (∼2% less) based on previously published data, which manifested as ∼0.5% more central corneal oedema.ConclusionsScleral lens induced corneal oedema is stromal in nature. On average, central stromal and total corneal thickness increased rapidly following lens insertion and peaked after 90 min, while central epithelial thickness gradually decreased throughout lens wear consistent with natural diurnal variation. A greater initial central corneal clearance resulted in reduced oxygen delivery to the cornea, which had minimal short-term impact upon healthy eyes, however, minimising central corneal clearance may be important in eyes with reduced endothelial cell function to minimise hypoxic stress.     

Fluid reservoir thickness and corneal oedema during closed eye scleral lens wear

PurposeTo examine the relationship between central post-lens fluid reservoir thickness and central corneal oedema during short-term closed eye scleral lens wear, and to compare these empirical oedema measurements with open eye lens wear data and current theoretical modelling for overnight scleral lens wear.MethodsTen participants (mean ± standard error 30 ± 1 years) with normal corneas wore scleral lenses (Dk 141 × 10⁻¹¹ cm³ O₂(cm)/[(sec.)(cm²)(mmHg)) under closed eye conditions on separate days with an initial central post-lens fluid reservoir thickness considered to be low (160 ± 7 μm), medium (494 ± 17 μm), or high (716 ± 16 μm). Epithelial, stromal, and total corneal oedema were measured using high-resolution optical coherence tomography immediately after lens application and following 90 min of wear, prior to lens removal. Data were compared to open eye scleral lens induced corneal oedema and a theoretical model of overnight closed eye scleral lens wear (Kim et al., 2018).ResultsCentral corneal oedema was primarily stromal in nature and increased with increasing fluid reservoir thickness; the mean total corneal oedema was 3.86 ± 0.50%, 4.71 ± 0.28% and 5.04 ± 0.42% for the low, medium, and high thickness conditions, respectively. A significant difference in stromal and total corneal oedema was observed between the low and high fluid reservoir thickness conditions only (both p ≤ 0.01). Theoretical modelling overestimated the magnitude of central corneal oedema and the influence of fluid reservoir thickness upon corneal oedema during closed eye conditions.ConclusionScleral lens induced central corneal oedema during closed eye lens wear increases with increasing fluid reservoir thickness, but at a decreased rate compared to theoretical modelling.     

Incomplete blinking: exposure keratopathy, lid wiper epitheliopathy, dry eye, refractive surgery, and dry contact lenses.

Exposure keratopathy, including that which occurs following laser assisted keratomileusis, appears to be associated with incomplete blinking. Incomplete blinking may contribute to the signs and symptoms of lid wiper epitheliopathy. In addition, precipitation of contact lens surface deposits and other contact lens surface drying phenomena, appear to be accelerated by incomplete blinking. For the inferior cornea or contact lens surface an incomplete blink approximately doubles the interblink interval and tear evaporation time, becoming even longer as blink rates reduce for computer and reading tasks. Inadequate aqueous, mucous and lipid distribution, as well as tear thinning over the exposed ocular or contact lens surface, may further increase the rate and significance of tear break-up and evaporation following an incomplete blink. Increased tear osmolarity that is associated with accelerated tear evaporation may also contribute to tissue changes and symptoms. Behaviour modification and habit reversal methods can be employed in the provision of blink efficiency exercises that are used to overcome incomplete blinking habits, with the potential to improve lipid, mucous and aqueous distribution so that exposure keratopathy, lid wiper epitheliopathy, and any associated symptoms are alleviated and/or prevented. Similarly, improved blink efficiency may help maintain lens surface condition and alleviate dryness symptoms for contact lens wearers. Lubricant drop instillation that is combined with blink efficiency exercises may increase the therapeutic benefit to corneal, conjunctival and lid wiper epithelium, as well as improving contact lens performance. Conditions of drop instillation, that reduce reflex blinking and tearing, may increase drop contact time and therapeutic benefit.     

The inside story: why contact lens cases become contaminated.

Contact lens case contamination has become an enigma, both because its role in the pathogenesis of lens-related keratitis has remained uncertain, and because current contact lens disinfection systems have been ineffective in eliminating it. This lecture reviews the evidence regarding the role of lens case contamination in the pathogenesis of keratitis and examines the reasons for the failure of disinfection systems to minimise lens case contamination.     

Masked comparison of two silicone hydrogel bandage contact lenses after photorefractive keratectomy

PurposeTo compare the efficiency and safety of two bandage contact lenses after photorefractive keratectomy (PRK).MethodsIn this double-blind study, 45 patients (90 eyes) received PRK in both eyes and wore bandage contact lenses (BCLs), PureVision (Bausch & Lomb, Rochester, NY, USA) in one eye and PureVision2 (Bausch & Lomb, Rochester, NY, USA) in the other eye, randomly assigned. The medication regimen after surgery was the same for both eyes. The epithelial defect's size, conjunctival hyperemia and lens centration were graded objectively using slit-lamp biomicroscopy on days 1, 3 and 5 after surgery. Also ocular symptoms of discomfort including tearing, photophobia, foreign body sensation and visual fluctuations were assessed subjectively at each visit.ResultsThe mean epithelial defect size on the first day after operation was similar in eyes fitted with PureVision (30.08 ± 5.30 mm²) and PureVision2 (30.25 ± 5.72 mm²) lenses. (p = 0.79) Contact lens deposits and bulbar hyperaemia on days 1 and 3 after PRK were similar between the two eyes, but were significantly greater on day 5 for PureVision2 lenses. (p = 0.02; p = 0.04 respectively) There was no difference in contact lens decentration, and discomfort symptoms including pain, tearing, foreign body sensation, photophobia and visual fluctuations between the eyes fitted with PureVision and PureVision2. (p > 0.05)ConclusionsPureVision and PureVision2 contact lenses are equivalent as bandage lenses in important aspects such as corneal re-epithelialization and subjective comfort., although PureVision2 led to a higher incidence of contact lens deposits and conjunctival hyperemia early post-PRK.