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Bulbar conjunctival staining in contact lens wearers and non lens wearers and its association with symptomatology
Contact Lens & Anterior Eye 28 (2005) 67–73 www.elsevier.com/locate/clae
Bulbar conjunctival staining in contact lens wearers and non lens wearers and its association with symptomatology Michel Guillon 1,*, Cecile Maissa 2 Optometric Technology Group, 42 Vauxhall Bridge Road, Pimlico, London SW 1V 2RX, UK
Abstract It has become increasingly apparent that bulbar conjunctival anomalies are associated with dry eye symptoms. Lissamine green (LG) and sodium fluorescein (FL) conjunctival staining were assessed in 102 soft contact lens wearers and 79 non contact lens wearers. Conjunctival staining was increased in symptomatic patients. Both LG and FL staining were discriminating factors for symptomatic non lens wearers (grade 1.5, p < 0.001). Only LG staining could discriminate symptomatic from asymptomatic lens wearers (grade 1.0, p = 0.007). This analysis confirms the involvement of the conjunctiva in dry eye symptomatology. While both stains are useful, LG shows greater specificity for symptomatic subjects, particularly in contact lens wearer. It is recommended that the examination of patients complaining of dry eyes, in particular contact lens wearing patients include as routine, the examination of the conjunctiva with lissamine green. # 2005 Published by Elsevier Ltd on behalf of British Contact Lens Association. Keywords: Lissamine green; Sodium fluorescein; Conjunctival staining; Soft contact lens; Symptoms
1. Introduction Between 20 and 30% of soft contact lens wearers suffer from symptoms of dryness during lens wear [1]. It is therefore not surprising that the primary reason for contact lens dropout is poor comfort. A survey of a US population in 1993 found that 72% of dropouts were due to poor comfort [2]. The precise mechanism of dryness in contact lens wear has been somewhat elusive. Many studies have investigated poor pre-lens tear film stability and numerous front surface deposits as causative factors for dryness in contact lens wear. One such study by Bruce et al. [3] suggested that there was no obvious relationship between these factors and symptoms in contact lens wearers. They put forward that the mechanism for dryness might be related to the bulbar conjunctiva rather than the anterior surface of the contact lens. This study investigates the proposition that ocular symptoms are associated with localised changes to the bulbar conjunctiva.
* Corresponding author. Tel.: +44 20 7932 9494; fax: +44 20 7976 5766. E-mail address: [email protected] (M. Guillon). 1 Ph.D. FCOptom FAAO CCTI. 2 Ph.D. AMIChemE Ingenieur ENSCP.
Recently, interest in conjunctival anomalies and their association with dry eye symptomatology has increased. Histo-pathological studies using impression cytology samples from the human conjunctiva have revealed reduced goblet cell density, squamous cell metaplasia, nuclear changes (chromatin condensation) and keratinisation in pathological dry eye [4]. Similar changes have been reported in contact lens wearers with the exception of keratinisation; these changes were apparent after just 1 week of contact lens wear [5]. Unlike corneal staining, conjunctival staining has not been extensively investigated. Sodium fluorescein (FL) is the most commonly used ophthalmic vital stain. Sodium fluorescein staining is present when epithelial cell-to-cell junctions are disrupted; it is also known to readily diffuse into the corneal stroma following compromisation of the epithelial barrier [6,7]. Sodium fluorescein is useful for examining damage to the corneal epithelium and therefore has numerous clinical applications for examining the cornea, including the assessment of ulcerative or traumatic lesions. Difficulties have been reported in visualising sodium fluorescein staining against the bright background luminance of the conjunctiva [8]. Rose bengal has been the main vital stain used to clinically evaluate the conjunctiva. The principal drawback
1367-0484/$ – see front matter # 2005 Published by Elsevier Ltd on behalf of British Contact Lens Association. doi:10.1016/j.clae.2005.02.002
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M. Guillon, C. Maissa / Contact Lens & Anterior Eye 28 (2005) 67–73
of rose bengal is the significant ocular discomfort associated with its instillation, which has limited its wide use in clinical practice [9,10]. Manning et al. [10] found that ocular irritation was less severe and of shorter duration with lissamine green (LG) than with rose bengal. They found that whilst dry eye patients experienced more severe irritation than normals, all participants preferred the lissamine green eye drop to rose bengal [10]. In vitro analysis has shown that lissamine green is intrinsically toxic to the ocular surface in a dose-dependent manner [7]. However, when exposure time was limited to 5 min more closely mimicking the situation in the human eye, where tears rapidly dilute the dye concentration, there was no toxic effect up to concentrations of 1% [7]; in the same study, 1% rose bengal produced significant toxicity [7]. The use of lissamine green to study the ocular surface was first suggested in 1973 [11], however, its use has been limited. A recent survey of US optometrists and ophthalmologists which sought first choice diagnostic tests for dry eye found that lissamine green staining was only used by 3% of clinicians [12]. However, lissamine green did feature amongst the four top preferred tests for 16% of clinicians. Unlike sodium fluorescein [13], lissamine green staining of the conjunctiva can be viewed in white light and without enhancing contrast filters. Many authors have suggested that lissamine green is a preferable alternative to rose bengal and that for all practical purposes they are the same tests [9,10,14,15]. However, systematic in vitro evaluation of these stains has shown that there are some substantial differences in their properties. Rose bengal stains exposed epithelial cells where the protective mucin layer of the tear film is absent, such as in mucin deficient dry eyes [4]. Therefore, rose bengal cannot differentiate between healthy and unhealthy cells. Chodosh et al. suggested that for this reason rose bengal is not by definition a vital stain [7]. Lissamine green, however, only stains damaged cells and is not blocked by mucin [7,16]. The clinical differences between lissamine green and rose bengal conjunctival staining in dry eye patients have been previously reported by Begley et al. who found that whilst the two stains affected similar locations, lissamine green staining covered larger areas [17]. A number of studies have reported on the value of lissamine green staining in assessing dry eye patients [4,9,14,18]. A large study of 100 dry eye patients and 100 controls found that severe lissamine green staining (Grade 3) only occurred in dry eye patients (87% versus 0%) [9]. Lissamine green staining was also present in sufferers of dry eye symptoms associated with poor air quality [19]. In that investigation, lissamine green conjunctival staining correlated with ocular irritation. Little is known about lissamine green staining in contact lens wearers. A study of 25 contact lens wearers whereby sodium fluorescein was used to evaluate the cornea and lissamine green to evaluate the conjunctiva found conjunctival lissamine green staining in 84% of subjects [17]. Sodium fluorescein corneal staining
was far less prominent only occurring in 40% of contact lens wearers. Evidence in the literature suggests that lissamine green can be used to detect conjunctiva changes induced by contact lens wear [17] and also those induced by dry eye amongst contact lens wearers [14], and non contact lens wearers [4,9,18]. The aim of this study was to assess the relative merit of sodium fluorescein and lissamine green stains to evaluate the conjunctiva in both contact lens wearers and non contact lens wearers. While some studies have suggested an association between conjunctival staining and dry eye symptoms in non contact lens wear [19], no study has been undertaken to evaluate the association of staining with symptoms in contact lens wearers.
2. Methods The subjects were recruited at random from patients presenting to the research clinic at Optometric Technology Group (London, UK). A total of 181 subjects were enrolled into the study comprising 79 non contact lens wearers and 102 daily soft contact lens wearers. Subject demographics are summarised in Table 1. The majority of contact lens wearers were female (65%) which is typical of contact lens wearing populations in the general community. In the non contact lens wearing population, there were slightly more males (58%) than females, and the average age was slightly older for the non contact lens wearing group (mean: 37 years versus 34 years). Subjects were excluded if there was evidence of significant ocular pathology or anomalies. Contact lens type was limited to daily wear soft contact lenses, rigid gas permeable or hard contact lens wearers were excluded. All the evaluations were conducted at one visit and ocular symptoms were quantified by McMonnies questionnaires [20,21]. Both non contact lens wearers and soft contact lens wearers attended with their own spectacle correction; soft contact lens wearers had not worn their contact lenses prior to being examined on the day of the visit. Lissamine green (Lissamine Green Ophthalmic strips, Rose Stone Enterprises) was instilled first with a sterile strip hydrated with non preserved buffered aerosol saline. Lissamine green staining was observed with the slit lamp biomicroscope using white light and graded separately for Table 1 Study population demographics (n = 181)
Mean age (years) Sex (males:females)
Non contact lens wearers (n = 79)
Contact lens wearers (n = 102)
37 15
34 10
46:33
36:66
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Fig. 1. Examples of conjunctival staining with sodium fluorescein viewed with cobalt blue filtered light, enhanced by Wratten #12 yellow filter (A) (Grade 2 = mild) and conjunctival staining with lissamine green in white light (B) (Grade 4 = severe).
each quadrant (nasal, temporal, inferior, superior). The same procedure was repeated with sodium fluorescein strips (Fluorets, Chauvin Pharmaceuticals) using both a cobalt blue filter and Kodak Wratten #12 yellow enhancement filter [13]. The staining observed was graded in each quadrant on a 5 point scale with 0.5 increments [22] as most commonly used in the contact lens or ophthalmic dry eye industry (0, no staining; 1, slight staining; 2, mild staining; 3, moderate staining; 4, severe staining). The staining rated was that corresponding to the exposed conjunctiva outside of the limbal area normally covered by the contact lens edge and potentially associated with mechanical staining. The maximum and median values of the grading obtained for the four quadrants were calculated for each eye. The fact that lissamine green staining was tested first should not have significantly impacted the sodium fluorescein staining result. It is known that lissamine green does not reach toxic levels within the residence times and concentrations achieved with topical application [7]. Clinical photographs of examples of conjunctival staining with the two stains are shown in Fig. 1A and B. Comparative statistics between symptomatic and asymptomatic subjects for both the non contact lens wearing and the contact lens wearing groups were carried out using a Mann–Whitney test. The Mann–Whitney test was also used to establish differences between contact lens wearers and non contact lens wearers. Chi square automated interaction
detector (CHAID) analysis [23,24] was used to identify discriminant factors and associated cut-off values for dryness symptomatology amongst the clinical findings.
3. Results The incidence of clinically significant conjunctival staining (Grade 2 or higher) was low, in both non contact lens wearers and soft contact lens wearers. However, soft contact lens wearers exhibited more sodium fluorescein (FL) staining than non contact lens wearers ( p = 0.019). Clinically significant conjunctival staining (mild or worse) was observed with sodium fluorescein amongst 16% of soft contact lens wearers compared to just 9% of non contact lens wearers (Table 2). There was no difference in lissamine green (LG) staining between contact lens wearers and non lens wearers ( p = 0.097). Clinically significant LG staining (mild or worse) occurred in 11% of non contact lens wearers and 14% of soft contact lens wearers (Table 2). Subjects were classified as either symptomatic or asymptomatic based on their responses to the McMonnies dry eye questionnaires. Symptomatic subjects were those who had a McMonnies score greater or equal to 40 [20]. Of the total population, 31% were classified as symptomatic. A much larger proportion was classified as symptomatic in the soft contact lens wearing group (43%) than in the non
Table 2 Distribution of maximum conjunctival sodium fluorescein (FL) and lissamine green (LG) staining comparing non contact lens wearers (n = 79) and soft contact lens wearers (n = 102) None (0)
Slight (0.5 and 1.0)
Mild (1.5–2.5)
Moderate (3.0)
Severe (4.0)
FL ( p = 0.019) Non contact lens wearers Contact lens wearers
46 38
44 47
9 15
0 1
0 0
LG ( p = 0.097) Non contact lens wearers Contact lens wearers
60 51
29 35
10 11
1 3
0 0
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Table 3 Distribution of maximum sodium fluorescein (FL) and lissamine green (LG) conjunctival staining grade for symptomatic (n = 12) and asymptomatic non contact lens wearers (n = 67) None (0)
Slight (0.5 and 1.0)
Mild (1.5–2.5)
Moderate (3.0)
Severe (4.0)
FL ( p < 0.001) Asymptomatic Symptomatic
52 17
43 50
5 33
0 0
0 0
LG ( p = 0.001) Asymptomatic Symptomatic
64 38
29 25
7 29
0 8
0 0
Table 4 Distribution of maximum sodium fluorescein (FL) and lissamine green (LG) conjunctival staining grade for symptomatic (n = 44) and asymptomatic soft contact lens wearers (n = 58) None (0)
Slight (0.5 and 1.0)
Mild (1.5–2.5)
Moderate (3.0)
Severe (4.0)
FL ( p = 0.018) Asymptomatic Symptomatic
40 34
50 42
10 22
0 2
0 0
LG ( p = 0.003) Asymptomatic Symptomatic
57 42
34 35
5 19
3 3
0 0
contact lens wearing group (15%). Both FL and LG stainings were found to be statistically significantly greater for the symptomatic subjects for both the non contact lens wearers (FL: p < 0.001; LG: p = 0.001) and the soft contact lens wearers (FL: p = 0.018; LG: p = 0.003) (Tables 3 and 4). Moreover, the incidence of mild or higher staining was greater for the symptomatic than for the asymptomatic groups with both vital stains (non contact lens wearers: FL, 33% versus 5% and LG, 29% versus 7%; Soft contact lens wearers: FL, 22% versus 8% and LG, 19% versus 5%). The differences observed between the symptomatic and asymptomatic groups were more pronounced with LG than with FL. When an individual exhibited LG staining, they frequently had FL staining also. The correlation between FL
and LG stainings were examined by regression analysis (Fig. 2A and B). A slightly more predictive relationship between LG and FL stainings was detected for soft contact lens wearers than for the non contact lens wearers. However, the correlations were moderate at best (non contact lens wearers r2 = 0.48; soft contact lens wearers r2 = 0.57). CHAID analysis identified the factors (discriminants) that best predict the characteristics of a population (response). In the current evaluation, symptomatology was the response and the maximum stainings observed with LG or FL in the worst quadrant were the discriminants. Higher levels of both LG and FL stainings were associated with greater symptomatology. In the non contact lens wearing group, the discriminant value for symptomatology
Fig. 2. Correlation between sodium fluorescein staining and lissamine green staining for non lens wearers (A) and soft contact lens wearers (B).
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Fig. 3. CHAID analysis of symptomatology in non contact lens wearers with conjunctival sodium fluorescein staining (maximum) as discriminant.
63.9% of subjects with LG staining Grade 0.0–0.5 were asymptomatic, whereas 65.3% of subjects with LG staining Grade 1.0 or greater were symptomatic.
4. Discussion
Fig. 4. CHAID analysis of symptomatology in non contact lens wearers with conjunctival lissamine green staining (maximum) as discriminant.
was Grade 1.5 maximum staining for both FL (Fig. 3, CHAID, p < 0.001) and LG (Fig. 4, CHAID, p < 0.001) vital stains. With sodium fluorescein, nearly all subjects below Grade 1.5 were asymptomatic (incidence of asymptomatic subjects: Grade 0 = 94.5%, Grade 0.5– 1.0 = 82.5%); in contrast less than half (46.7%) of subjects with Grade 1.5 or greater were asymptomatic. With lissamine green, the same level of discrimination was achieved: 89.1% of the subjects with Grade 0.0–1.0 were asymptomatic; in contrast 50.0% of the subjects with Grade 1.5 or greater were symptomatic. For the soft contact lens wearing group, only LG staining was a discriminating factor for symptomatic subjects and the discriminant value was Grade 1.0 maximum staining (Fig. 5, CHAID, p = 0.007):
Fig. 5. CHAID analysis of symptomatology in soft contact lens wearers with conjunctival lissamine green staining (maximum) as discriminant.
Previous studies have found that conjunctival staining was observed more often in dry eye patients than in normals [9]. This study confirmed that the bulbar conjunctiva is involved in the pathogenesis of dry eye symptoms. Prior to this study, a relationship between dry eye symptoms and conjunctival staining had only been established in a normal non contact lens wearing population [19]. The current study, which examined two representative populations of a general eye care practice, free of significant ocular pathology found increased conjunctival staining in symptomatic subjects in both non contact lens wearers and soft contact lens wearers. The findings show that the evaluation of the conjunctiva is highly relevant to ocular symptomatology and supports the recommendation to include conjunctival analysis in any work up of ocular surface disease sufferers, marginal dry eye patients or symptomatic contact lens wearers. Clinical diagnosis for dry eye is often based on a series of tests rather than just one test. In one study of dry eye, criteria for diagnosis required positive results for two out of three of the following tests: tear volume (Schirmer), tear film stability (TBUT) and vital stain (rose bengal staining) [9]. A recent publication investigating the validity of the ocular surface disease index used a similar battery of tests, but used the same stains as in this study for the clinical diagnosis [25]. Schirmer test and TBUT were both included, but the vital stains were sodium fluorescein and lissamine green. Use of rose bengal has been criticised due to the irritation it causes [9,10] and the fact that it is not specific to damaged cells [7]. Alternate stains, such as lissamine green, have been found to be well tolerated and to provide useful clinical information as shown in the present study. The current results advocate the use of this alternate stain for conjunctival surface assessment. The pattern of staining observed confirmed existing reports that contact lens wear causes changes to the
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conjunctiva not confined to the area corresponding to the lens edge [4]. Moreover, in this study, the evaluation was conducted prior to contact lens wear on the day of the visit; and therefore represents more than just transient compression of the mucin layer by the lens edge. Histological studies have shown that specimens taken from the conjunctiva by impression cytology exhibit more pronounced changes in areas that the contact lens would cover, particularly at 6 and 12 o’clock, than further away in the conjunctiva [5]. The hypothesis put forward for the staining observed outside of the conjunctival area covered by the contact lens is an evaporative aetiology. The presence of a contact lens modifies the corneal component of the sensory mechanism involved in blinking. When a blink takes place, the pre contact lens tear film is no longer continuous leading to highly increased friction. The contact lens destabilises the tear film; a recent study has shown that the mean tear film break up time decreases from 14.5 s prior to contact lens wear to 7.0 s during contact lens wear [26]. The destabilisation of the pre lens tear film propagates to the bulbar conjunctiva, so that during the blink, the lubrication of the conjunctiva is incomplete and the increased friction produces both tissue damage depicted with the vital stains and symptoms reported by the wearer in the standardised questionnaire. Sodium fluorescein and lissamine green conjunctival stainings were both increased in symptomatic compared to asymptomatic contact lens wearers. The association between the two stains was, however, tenuous; this weak association may be explained by the different modes of action of the two stains. In vitro analysis of sodium fluorescein has shown it to label gaps in cell–cell junctions. Lissamine green also stains gaps in cell–cell junctions, but in addition stains dead or degenerated cells [7]. Lissamine green conjunctival staining was generally more prominent than sodium fluorescein conjunctival staining in symptomatic subjects. In fact, only clinically significant lissamine green staining was found as a discriminating factor for symptomatic contact lens wearers. While sodium fluorescein staining was increased in symptomatic contact lens wearers, staining was not found to be statistically discriminating for symptomatic contact lens wearers. Sodium fluorescein staining increases generally with contact lens wear, so it is possible that this may mask any increase in sodium fluorescein conjunctival staining particularly for symptomatic contact lens wearers. These observations suggest greater sensitivity for lissamine green as well as more relevance to symptomatology, than sodium fluorescein in soft contact lens wearers. A discriminating level of Grade 1 (slight) or more is suggested. Franck [27] has suggested as diagnostic criteria for the clinical evaluation of dry eye in non contact lens wearers combining TBUT and lissamine green conjunctival staining. These suggestions are in general agreement with the findings in the current study of the relevance of mild conjunctival staining to dry eye symptoms.
If conjunctival staining is evaluated upon contact lens removal, the staining to judge is the exposure staining found outside of the limbal part covered by the contact lens edge. The mechanical staining associated to the contact lens edge is not relevant to the current discrimination. Mild to moderate conjunctival staining was also associated with dry eye symptoms in non contact lens wearers. The level of conjunctival staining was discriminating with both sodium fluorescein and lissamine green.
5. Conclusions The uses of both sodium fluorescein and lissamine green staining outside of the limbal zone normally covered by the contact lens have been shown to be viable means to evaluate the bulbar conjunctiva and to be highly relevant to the investigation of dry eye symptomatic patients. Lissamine green conjunctival staining was of particular use for soft contact lens wearers where symptoms of dryness, which were a prominent complaint, were associated with elevated staining. Conjunctival staining was shown to be more frequent with contact lens wearers than non contact lens wearers and within each group for symptomatic than asymptomatic subjects.
References [1] Robboy M, Orsborn G. The responses of marginal dry eye lens wearers to a dry eye survey. Contact lens J 1989;17:8–9. [2] Schlanger JL, Schwartz CA, Leser E. Happy patients: connecting comfort and compliance. Spectrum 1993;8:45–7. [3] Bruce AS, Golding TR, Au SWM, Rowhani H. Mechanisms of dryness in soft lens wear—role of BUT and deposits. Clin Exp Optom 1995;78:168–75. [4] Bron AJ. Non-Sjo¨ gren dry eye: pathogenesis diagnosis and animal models. In: Sullivan DA, editor. Lacrimal gland, tear film, and dry eye syndromes. New York: Plenum Press, 1994. p. 471–88. [5] Knop E, Brewitt H. Morphology of the conjunctival epithelium in spectacle and contact lens wearers—a light and electron microscopic study. Contactologia 1992;14:108–12. [6] Feenstra RPG, Tseng SCG. Comparison of fluorescein and rose Bengal staining. Ophthalmology 1992;99:605–17. [7] Chodosh J, Dix RD, Howell RC, Stroop WG, Tseng SCG. Staining characteristics and antiviral activity of sulforhodamine B and lissamine green B. Invest Ophthalmol Vis Sci 1994;35:1046–58. [8] Eliason JA, Maurice DM. Staining of the conjunctiva and conjunctival tear film. Br J Ophthalmol 1990;74:519–22. [9] Khurana AK, Chaudhary R, Ahluwalia BK, Gupta S. Tear film profile in dry eye. Acta Ophthalmol (Copenh) 1991;69:79–86. [10] Manning FJ, Wehrly SR, Foulks GN. Patient tolerance and ocular surface staining characteristics of lissamine green versus rose bengal. Ophthalmology 1995;102:1953–7. [11] Norn MS. Lissamine green. Vital staining of cornea and conjunctiva. Acta Ophthalmol (Copenh) 1973;51:483–91. [12] Korb D. Survey of preferred tests for diagnosis of tear film disorders and dry eye. Optom Vis Sci 1999;76(12s):227. [13] Song A, Schmidlap B, Bradley A, Begley CG. Filters for enhanced viewing of conjunctival staining with rose bengal, lissamine green and fluorescein. Optom Vis Sci 1999;76(12s):231.
M. Guillon, C. Maissa / Contact Lens & Anterior Eye 28 (2005) 67–73 [14] Kinney KA. Detecting dry eye in contact lens wearers contact lens spectrum 1998;5:21–8. [15] Creuzot-Garcher C. L’examen clinique du film lacrymal. J Fr Ophthalmol 1999;22:461–6. [16] Kim J, Foulks GN. Evaluation of the effect of lissamine green and rose bengal on human corneal epithelial cells. Cornea 1999;18:328–32. [17] Begley CG, Ashman MC, Wright AR, Malinovsky VE. Comparison of rose bengal and lissamine green conjunctival staining in dry eye patients. Optom Vis Sci 1998;75(12s):62. [18] Konkel CN, Pikal AJ, Begley CG, Caffery B. Rose bengal and lissamine green conjunctival staining in dry eye patients. Optom Vis Sci 1999;76(12s):229. [19] Franck C. Eye symptoms and signs in buildings with indoor climate problems (‘office eye syndrome’). Acta Ophthalmol (Copenh) 1986;64:306–11. [20] McMonnies CW, Ho A. Marginal dry eye diagnosis: history versus biomicroscopy. In: Holly FJ, editor. The pre-ocular tear film in health, disease and contact lens wear. Texas: Lubbock, Dry Eye Institute, 1986. p. 32–40.
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[21] Guillon M, Allary JC, Guillon JP, Orsborn G. Clinical management of regular replacement: Part 1. Selection of replacement frequency. ICLC 1992;19:104–20. [22] Guillon M, McGrogan L, Maissa C. Conventional and new corneal fluorescein staining grading scales—population characteristics. Optom Vis Sci 1997;74(12s):101. [23] Kass G. An exploratory technique for investigating for large quantities of categorical data. Appl Stat 1980;29:119–27. [24] Biggs D, DeVille B, Suen E. A method of choosing multiway partitions for classification and decision trees. J Appl Stat 1991;18:49–62. [25] Schiffman RM, Christianson MD, Jacobsen G, Hirsch JD, Reis BL. Reliability and validity of the ocular surface disease index. Arch Ophthalmol 2000;118:615–21. [26] Guillon M, Styles E, Guillon JP, Maissa C. Preocular tear film characteristics of non wearers and soft contact lens wearers. Optom Vis Sci 1997;74(5):273–9. [27] Franck C. Fatty layer of the precorneal film in the ‘office eye syndrome’. Acta Ophthalmol (Copenh) 1991;69:737–43.
Bulbar conjunctival staining in contact lens wearers and non lens wearers and its association with symptomatology Michel Guillon 1,*, Cecile Maissa 2 Optometric Technology Group, 42 Vauxhall Bridge Road, Pimlico, London SW 1V 2RX, UK
Abstract It has become increasingly apparent that bulbar conjunctival anomalies are associated with dry eye symptoms. Lissamine green (LG) and sodium fluorescein (FL) conjunctival staining were assessed in 102 soft contact lens wearers and 79 non contact lens wearers. Conjunctival staining was increased in symptomatic patients. Both LG and FL staining were discriminating factors for symptomatic non lens wearers (grade 1.5, p < 0.001). Only LG staining could discriminate symptomatic from asymptomatic lens wearers (grade 1.0, p = 0.007). This analysis confirms the involvement of the conjunctiva in dry eye symptomatology. While both stains are useful, LG shows greater specificity for symptomatic subjects, particularly in contact lens wearer. It is recommended that the examination of patients complaining of dry eyes, in particular contact lens wearing patients include as routine, the examination of the conjunctiva with lissamine green. # 2005 Published by Elsevier Ltd on behalf of British Contact Lens Association. Keywords: Lissamine green; Sodium fluorescein; Conjunctival staining; Soft contact lens; Symptoms
1. Introduction Between 20 and 30% of soft contact lens wearers suffer from symptoms of dryness during lens wear [1]. It is therefore not surprising that the primary reason for contact lens dropout is poor comfort. A survey of a US population in 1993 found that 72% of dropouts were due to poor comfort [2]. The precise mechanism of dryness in contact lens wear has been somewhat elusive. Many studies have investigated poor pre-lens tear film stability and numerous front surface deposits as causative factors for dryness in contact lens wear. One such study by Bruce et al. [3] suggested that there was no obvious relationship between these factors and symptoms in contact lens wearers. They put forward that the mechanism for dryness might be related to the bulbar conjunctiva rather than the anterior surface of the contact lens. This study investigates the proposition that ocular symptoms are associated with localised changes to the bulbar conjunctiva.
* Corresponding author. Tel.: +44 20 7932 9494; fax: +44 20 7976 5766. E-mail address: [email protected] (M. Guillon). 1 Ph.D. FCOptom FAAO CCTI. 2 Ph.D. AMIChemE Ingenieur ENSCP.
Recently, interest in conjunctival anomalies and their association with dry eye symptomatology has increased. Histo-pathological studies using impression cytology samples from the human conjunctiva have revealed reduced goblet cell density, squamous cell metaplasia, nuclear changes (chromatin condensation) and keratinisation in pathological dry eye [4]. Similar changes have been reported in contact lens wearers with the exception of keratinisation; these changes were apparent after just 1 week of contact lens wear [5]. Unlike corneal staining, conjunctival staining has not been extensively investigated. Sodium fluorescein (FL) is the most commonly used ophthalmic vital stain. Sodium fluorescein staining is present when epithelial cell-to-cell junctions are disrupted; it is also known to readily diffuse into the corneal stroma following compromisation of the epithelial barrier [6,7]. Sodium fluorescein is useful for examining damage to the corneal epithelium and therefore has numerous clinical applications for examining the cornea, including the assessment of ulcerative or traumatic lesions. Difficulties have been reported in visualising sodium fluorescein staining against the bright background luminance of the conjunctiva [8]. Rose bengal has been the main vital stain used to clinically evaluate the conjunctiva. The principal drawback
1367-0484/$ – see front matter # 2005 Published by Elsevier Ltd on behalf of British Contact Lens Association. doi:10.1016/j.clae.2005.02.002
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of rose bengal is the significant ocular discomfort associated with its instillation, which has limited its wide use in clinical practice [9,10]. Manning et al. [10] found that ocular irritation was less severe and of shorter duration with lissamine green (LG) than with rose bengal. They found that whilst dry eye patients experienced more severe irritation than normals, all participants preferred the lissamine green eye drop to rose bengal [10]. In vitro analysis has shown that lissamine green is intrinsically toxic to the ocular surface in a dose-dependent manner [7]. However, when exposure time was limited to 5 min more closely mimicking the situation in the human eye, where tears rapidly dilute the dye concentration, there was no toxic effect up to concentrations of 1% [7]; in the same study, 1% rose bengal produced significant toxicity [7]. The use of lissamine green to study the ocular surface was first suggested in 1973 [11], however, its use has been limited. A recent survey of US optometrists and ophthalmologists which sought first choice diagnostic tests for dry eye found that lissamine green staining was only used by 3% of clinicians [12]. However, lissamine green did feature amongst the four top preferred tests for 16% of clinicians. Unlike sodium fluorescein [13], lissamine green staining of the conjunctiva can be viewed in white light and without enhancing contrast filters. Many authors have suggested that lissamine green is a preferable alternative to rose bengal and that for all practical purposes they are the same tests [9,10,14,15]. However, systematic in vitro evaluation of these stains has shown that there are some substantial differences in their properties. Rose bengal stains exposed epithelial cells where the protective mucin layer of the tear film is absent, such as in mucin deficient dry eyes [4]. Therefore, rose bengal cannot differentiate between healthy and unhealthy cells. Chodosh et al. suggested that for this reason rose bengal is not by definition a vital stain [7]. Lissamine green, however, only stains damaged cells and is not blocked by mucin [7,16]. The clinical differences between lissamine green and rose bengal conjunctival staining in dry eye patients have been previously reported by Begley et al. who found that whilst the two stains affected similar locations, lissamine green staining covered larger areas [17]. A number of studies have reported on the value of lissamine green staining in assessing dry eye patients [4,9,14,18]. A large study of 100 dry eye patients and 100 controls found that severe lissamine green staining (Grade 3) only occurred in dry eye patients (87% versus 0%) [9]. Lissamine green staining was also present in sufferers of dry eye symptoms associated with poor air quality [19]. In that investigation, lissamine green conjunctival staining correlated with ocular irritation. Little is known about lissamine green staining in contact lens wearers. A study of 25 contact lens wearers whereby sodium fluorescein was used to evaluate the cornea and lissamine green to evaluate the conjunctiva found conjunctival lissamine green staining in 84% of subjects [17]. Sodium fluorescein corneal staining
was far less prominent only occurring in 40% of contact lens wearers. Evidence in the literature suggests that lissamine green can be used to detect conjunctiva changes induced by contact lens wear [17] and also those induced by dry eye amongst contact lens wearers [14], and non contact lens wearers [4,9,18]. The aim of this study was to assess the relative merit of sodium fluorescein and lissamine green stains to evaluate the conjunctiva in both contact lens wearers and non contact lens wearers. While some studies have suggested an association between conjunctival staining and dry eye symptoms in non contact lens wear [19], no study has been undertaken to evaluate the association of staining with symptoms in contact lens wearers.
2. Methods The subjects were recruited at random from patients presenting to the research clinic at Optometric Technology Group (London, UK). A total of 181 subjects were enrolled into the study comprising 79 non contact lens wearers and 102 daily soft contact lens wearers. Subject demographics are summarised in Table 1. The majority of contact lens wearers were female (65%) which is typical of contact lens wearing populations in the general community. In the non contact lens wearing population, there were slightly more males (58%) than females, and the average age was slightly older for the non contact lens wearing group (mean: 37 years versus 34 years). Subjects were excluded if there was evidence of significant ocular pathology or anomalies. Contact lens type was limited to daily wear soft contact lenses, rigid gas permeable or hard contact lens wearers were excluded. All the evaluations were conducted at one visit and ocular symptoms were quantified by McMonnies questionnaires [20,21]. Both non contact lens wearers and soft contact lens wearers attended with their own spectacle correction; soft contact lens wearers had not worn their contact lenses prior to being examined on the day of the visit. Lissamine green (Lissamine Green Ophthalmic strips, Rose Stone Enterprises) was instilled first with a sterile strip hydrated with non preserved buffered aerosol saline. Lissamine green staining was observed with the slit lamp biomicroscope using white light and graded separately for Table 1 Study population demographics (n = 181)
Mean age (years) Sex (males:females)
Non contact lens wearers (n = 79)
Contact lens wearers (n = 102)
37 15
34 10
46:33
36:66
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Fig. 1. Examples of conjunctival staining with sodium fluorescein viewed with cobalt blue filtered light, enhanced by Wratten #12 yellow filter (A) (Grade 2 = mild) and conjunctival staining with lissamine green in white light (B) (Grade 4 = severe).
each quadrant (nasal, temporal, inferior, superior). The same procedure was repeated with sodium fluorescein strips (Fluorets, Chauvin Pharmaceuticals) using both a cobalt blue filter and Kodak Wratten #12 yellow enhancement filter [13]. The staining observed was graded in each quadrant on a 5 point scale with 0.5 increments [22] as most commonly used in the contact lens or ophthalmic dry eye industry (0, no staining; 1, slight staining; 2, mild staining; 3, moderate staining; 4, severe staining). The staining rated was that corresponding to the exposed conjunctiva outside of the limbal area normally covered by the contact lens edge and potentially associated with mechanical staining. The maximum and median values of the grading obtained for the four quadrants were calculated for each eye. The fact that lissamine green staining was tested first should not have significantly impacted the sodium fluorescein staining result. It is known that lissamine green does not reach toxic levels within the residence times and concentrations achieved with topical application [7]. Clinical photographs of examples of conjunctival staining with the two stains are shown in Fig. 1A and B. Comparative statistics between symptomatic and asymptomatic subjects for both the non contact lens wearing and the contact lens wearing groups were carried out using a Mann–Whitney test. The Mann–Whitney test was also used to establish differences between contact lens wearers and non contact lens wearers. Chi square automated interaction
detector (CHAID) analysis [23,24] was used to identify discriminant factors and associated cut-off values for dryness symptomatology amongst the clinical findings.
3. Results The incidence of clinically significant conjunctival staining (Grade 2 or higher) was low, in both non contact lens wearers and soft contact lens wearers. However, soft contact lens wearers exhibited more sodium fluorescein (FL) staining than non contact lens wearers ( p = 0.019). Clinically significant conjunctival staining (mild or worse) was observed with sodium fluorescein amongst 16% of soft contact lens wearers compared to just 9% of non contact lens wearers (Table 2). There was no difference in lissamine green (LG) staining between contact lens wearers and non lens wearers ( p = 0.097). Clinically significant LG staining (mild or worse) occurred in 11% of non contact lens wearers and 14% of soft contact lens wearers (Table 2). Subjects were classified as either symptomatic or asymptomatic based on their responses to the McMonnies dry eye questionnaires. Symptomatic subjects were those who had a McMonnies score greater or equal to 40 [20]. Of the total population, 31% were classified as symptomatic. A much larger proportion was classified as symptomatic in the soft contact lens wearing group (43%) than in the non
Table 2 Distribution of maximum conjunctival sodium fluorescein (FL) and lissamine green (LG) staining comparing non contact lens wearers (n = 79) and soft contact lens wearers (n = 102) None (0)
Slight (0.5 and 1.0)
Mild (1.5–2.5)
Moderate (3.0)
Severe (4.0)
FL ( p = 0.019) Non contact lens wearers Contact lens wearers
46 38
44 47
9 15
0 1
0 0
LG ( p = 0.097) Non contact lens wearers Contact lens wearers
60 51
29 35
10 11
1 3
0 0
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Table 3 Distribution of maximum sodium fluorescein (FL) and lissamine green (LG) conjunctival staining grade for symptomatic (n = 12) and asymptomatic non contact lens wearers (n = 67) None (0)
Slight (0.5 and 1.0)
Mild (1.5–2.5)
Moderate (3.0)
Severe (4.0)
FL ( p < 0.001) Asymptomatic Symptomatic
52 17
43 50
5 33
0 0
0 0
LG ( p = 0.001) Asymptomatic Symptomatic
64 38
29 25
7 29
0 8
0 0
Table 4 Distribution of maximum sodium fluorescein (FL) and lissamine green (LG) conjunctival staining grade for symptomatic (n = 44) and asymptomatic soft contact lens wearers (n = 58) None (0)
Slight (0.5 and 1.0)
Mild (1.5–2.5)
Moderate (3.0)
Severe (4.0)
FL ( p = 0.018) Asymptomatic Symptomatic
40 34
50 42
10 22
0 2
0 0
LG ( p = 0.003) Asymptomatic Symptomatic
57 42
34 35
5 19
3 3
0 0
contact lens wearing group (15%). Both FL and LG stainings were found to be statistically significantly greater for the symptomatic subjects for both the non contact lens wearers (FL: p < 0.001; LG: p = 0.001) and the soft contact lens wearers (FL: p = 0.018; LG: p = 0.003) (Tables 3 and 4). Moreover, the incidence of mild or higher staining was greater for the symptomatic than for the asymptomatic groups with both vital stains (non contact lens wearers: FL, 33% versus 5% and LG, 29% versus 7%; Soft contact lens wearers: FL, 22% versus 8% and LG, 19% versus 5%). The differences observed between the symptomatic and asymptomatic groups were more pronounced with LG than with FL. When an individual exhibited LG staining, they frequently had FL staining also. The correlation between FL
and LG stainings were examined by regression analysis (Fig. 2A and B). A slightly more predictive relationship between LG and FL stainings was detected for soft contact lens wearers than for the non contact lens wearers. However, the correlations were moderate at best (non contact lens wearers r2 = 0.48; soft contact lens wearers r2 = 0.57). CHAID analysis identified the factors (discriminants) that best predict the characteristics of a population (response). In the current evaluation, symptomatology was the response and the maximum stainings observed with LG or FL in the worst quadrant were the discriminants. Higher levels of both LG and FL stainings were associated with greater symptomatology. In the non contact lens wearing group, the discriminant value for symptomatology
Fig. 2. Correlation between sodium fluorescein staining and lissamine green staining for non lens wearers (A) and soft contact lens wearers (B).
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Fig. 3. CHAID analysis of symptomatology in non contact lens wearers with conjunctival sodium fluorescein staining (maximum) as discriminant.
63.9% of subjects with LG staining Grade 0.0–0.5 were asymptomatic, whereas 65.3% of subjects with LG staining Grade 1.0 or greater were symptomatic.
4. Discussion
Fig. 4. CHAID analysis of symptomatology in non contact lens wearers with conjunctival lissamine green staining (maximum) as discriminant.
was Grade 1.5 maximum staining for both FL (Fig. 3, CHAID, p < 0.001) and LG (Fig. 4, CHAID, p < 0.001) vital stains. With sodium fluorescein, nearly all subjects below Grade 1.5 were asymptomatic (incidence of asymptomatic subjects: Grade 0 = 94.5%, Grade 0.5– 1.0 = 82.5%); in contrast less than half (46.7%) of subjects with Grade 1.5 or greater were asymptomatic. With lissamine green, the same level of discrimination was achieved: 89.1% of the subjects with Grade 0.0–1.0 were asymptomatic; in contrast 50.0% of the subjects with Grade 1.5 or greater were symptomatic. For the soft contact lens wearing group, only LG staining was a discriminating factor for symptomatic subjects and the discriminant value was Grade 1.0 maximum staining (Fig. 5, CHAID, p = 0.007):
Fig. 5. CHAID analysis of symptomatology in soft contact lens wearers with conjunctival lissamine green staining (maximum) as discriminant.
Previous studies have found that conjunctival staining was observed more often in dry eye patients than in normals [9]. This study confirmed that the bulbar conjunctiva is involved in the pathogenesis of dry eye symptoms. Prior to this study, a relationship between dry eye symptoms and conjunctival staining had only been established in a normal non contact lens wearing population [19]. The current study, which examined two representative populations of a general eye care practice, free of significant ocular pathology found increased conjunctival staining in symptomatic subjects in both non contact lens wearers and soft contact lens wearers. The findings show that the evaluation of the conjunctiva is highly relevant to ocular symptomatology and supports the recommendation to include conjunctival analysis in any work up of ocular surface disease sufferers, marginal dry eye patients or symptomatic contact lens wearers. Clinical diagnosis for dry eye is often based on a series of tests rather than just one test. In one study of dry eye, criteria for diagnosis required positive results for two out of three of the following tests: tear volume (Schirmer), tear film stability (TBUT) and vital stain (rose bengal staining) [9]. A recent publication investigating the validity of the ocular surface disease index used a similar battery of tests, but used the same stains as in this study for the clinical diagnosis [25]. Schirmer test and TBUT were both included, but the vital stains were sodium fluorescein and lissamine green. Use of rose bengal has been criticised due to the irritation it causes [9,10] and the fact that it is not specific to damaged cells [7]. Alternate stains, such as lissamine green, have been found to be well tolerated and to provide useful clinical information as shown in the present study. The current results advocate the use of this alternate stain for conjunctival surface assessment. The pattern of staining observed confirmed existing reports that contact lens wear causes changes to the
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conjunctiva not confined to the area corresponding to the lens edge [4]. Moreover, in this study, the evaluation was conducted prior to contact lens wear on the day of the visit; and therefore represents more than just transient compression of the mucin layer by the lens edge. Histological studies have shown that specimens taken from the conjunctiva by impression cytology exhibit more pronounced changes in areas that the contact lens would cover, particularly at 6 and 12 o’clock, than further away in the conjunctiva [5]. The hypothesis put forward for the staining observed outside of the conjunctival area covered by the contact lens is an evaporative aetiology. The presence of a contact lens modifies the corneal component of the sensory mechanism involved in blinking. When a blink takes place, the pre contact lens tear film is no longer continuous leading to highly increased friction. The contact lens destabilises the tear film; a recent study has shown that the mean tear film break up time decreases from 14.5 s prior to contact lens wear to 7.0 s during contact lens wear [26]. The destabilisation of the pre lens tear film propagates to the bulbar conjunctiva, so that during the blink, the lubrication of the conjunctiva is incomplete and the increased friction produces both tissue damage depicted with the vital stains and symptoms reported by the wearer in the standardised questionnaire. Sodium fluorescein and lissamine green conjunctival stainings were both increased in symptomatic compared to asymptomatic contact lens wearers. The association between the two stains was, however, tenuous; this weak association may be explained by the different modes of action of the two stains. In vitro analysis of sodium fluorescein has shown it to label gaps in cell–cell junctions. Lissamine green also stains gaps in cell–cell junctions, but in addition stains dead or degenerated cells [7]. Lissamine green conjunctival staining was generally more prominent than sodium fluorescein conjunctival staining in symptomatic subjects. In fact, only clinically significant lissamine green staining was found as a discriminating factor for symptomatic contact lens wearers. While sodium fluorescein staining was increased in symptomatic contact lens wearers, staining was not found to be statistically discriminating for symptomatic contact lens wearers. Sodium fluorescein staining increases generally with contact lens wear, so it is possible that this may mask any increase in sodium fluorescein conjunctival staining particularly for symptomatic contact lens wearers. These observations suggest greater sensitivity for lissamine green as well as more relevance to symptomatology, than sodium fluorescein in soft contact lens wearers. A discriminating level of Grade 1 (slight) or more is suggested. Franck [27] has suggested as diagnostic criteria for the clinical evaluation of dry eye in non contact lens wearers combining TBUT and lissamine green conjunctival staining. These suggestions are in general agreement with the findings in the current study of the relevance of mild conjunctival staining to dry eye symptoms.
If conjunctival staining is evaluated upon contact lens removal, the staining to judge is the exposure staining found outside of the limbal part covered by the contact lens edge. The mechanical staining associated to the contact lens edge is not relevant to the current discrimination. Mild to moderate conjunctival staining was also associated with dry eye symptoms in non contact lens wearers. The level of conjunctival staining was discriminating with both sodium fluorescein and lissamine green.
5. Conclusions The uses of both sodium fluorescein and lissamine green staining outside of the limbal zone normally covered by the contact lens have been shown to be viable means to evaluate the bulbar conjunctiva and to be highly relevant to the investigation of dry eye symptomatic patients. Lissamine green conjunctival staining was of particular use for soft contact lens wearers where symptoms of dryness, which were a prominent complaint, were associated with elevated staining. Conjunctival staining was shown to be more frequent with contact lens wearers than non contact lens wearers and within each group for symptomatic than asymptomatic subjects.
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