Corneal staining is a valuable clinical tool for assessing corneal epithelial integrity at the slit lamp. Recent reports of clinically significant corneal staining with silicone hydrogel lenses have highlighted the importance of understanding the interaction of lenses, lens care solutions and the corneal surface. Understanding these relationships and integrating the study findings into the current body of knowledge requires comparable data from multiple studies. This is difficult to achieve when investigators use different patient populations, different scales to generate staining scores and different benchmarks for staining intensity and clinical severity. Sliding Scales We have no universal standard for grading the extent or severity of corneal staining.
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Corneal staining is a valuable clinical tool for assessing corneal epithelial integrity at the slit lamp. Recent reports of clinically significant corneal staining with silicone hydrogel lenses have highlighted the importance of understanding the interaction of lenses, lens care solutions and the corneal surface.
Understanding these relationships and integrating the study findings into the current body of knowledge requires comparable data from multiple studies. This is difficult to achieve when investigators use different patient populations, different scales to generate staining scores and different benchmarks for staining intensity and clinical severity. Sliding Scales We have no universal standard for grading the extent or severity of corneal staining.
The major grading scales are not in congruence with one another. The scales currently employed are subject to differences in grading precision between different observers inter-reader reliability and between one test and another for the same observer intra-reader reliability.
In an interesting study that examined how investigators assess corneal staining, Begley et al reported that there was significant inter-reader variability in how the investigators within a multicenter study arrived at the final corneal staining score, even though all three sites were provided with the same guide for assessing corneal staining.
The authors demonstrated that, depending upon the process used, two investigators could report significantly different scores for the same level of corneal staining. In one study presented here, a multipurpose solution marketed under different names but used with the same silicone hydrogel lens and evaluated using the same scale, produced variations in staining results. Practitioners should pay careful attention to the grading scales, study designs, populations studied and the consistency of results from several studies before relying on the conclusions presented in any given report.
Traditional Corneal Staining Grading Scales Corneal staining grading scales were developed to help clinicians monitor changes of the cornea and choose a course of action. Clinicians observe the corneal surface under the slit lamp, compare it to written descriptions, photographic, artist-rendered or computer-generated images of different severities of corneal staining and assign a grade based on one or more elements of the staining and the number of zones of staining on the cornea.
The grading systems help clinicians assess which corneal staining patterns are within the range of normal and which are pathological and in need of therapeutic intervention. Each of the major grading systems employs a method of dividing the cornea into zones and for evaluating one or more staining variables in each zone.
In the five-zone model, Zone 1 is a circle in the center of the cornea and the four equal segments of the ring surrounding this central zone are Zones 2 through 5 superior, temporal, nasal and inferior zones. Type 0 means there is no staining. Type 1 is micropunctate; Type 2, macropunctate; Type 3, coalescent macropunctate staining; and Type 4 is a coalescent patch of 1mm or greater in size. Figure 1. Used with permission.
If there is no staining, the depth is graded as 0. Superficial epithelial involvement is Grade 1. The presence of a stromal glow within 30 seconds is Grade 2. An immediate localized stromal glow is Grade 3, and immediate diffuse stromal glow is Grade 4. If there is no staining, the extent is graded as 0. From 1 to 15 percent of surface involvement is Grade 1, 16 to 30 percent surface involvement is Grade 2, 31 to 45 percent surface involvement is Grade 3 and 46 percent or greater surface involvement is Grade 4.
Micropunctate staining is considered not clinically significant by the CCLRU unless it involves more than 15 percent of the corneal surface. Under this system, the type of staining in each zone is graded on a 0 none to total scale. The mean outcome measure, the Global Staining Score, is the product of the type of staining in each of five zones one central and four peripheral times the percentage area of the zone with the staining.
Under this system, the scale ranges from 0 none per zone to 50, total staining in all 5 zones. Recently, the scoring was modified slightly in an attempt to normalize the scores to represent a typical score for a given sector. The Global Staining Score is now divided by 5, for a maximum average sector staining score of 10, For example, one corneal sector with micropunctate staining score 25 over 10 percent of its surface would have a total score of 25 x If all five sectors had the same score, the total score would be 1, x 5 , but this would be normalized to An average sector score of less than about 1, or total Global Staining Score of 6, is considered clinically insignificant.
Figure 2 shows the representative staining score for each of the CCLR types of punctate fluorescein staining. Figure 2. Global staining scores are shown for each type of punctate fluorescein staining CCLR standards.
Differences among the leading grading systems appear in Table 1. Researchers used a modified CCLRU scale, the pairs of lenses and solutions have different numbers of subjects, and the same solution marketed under different brand names produced different staining scores. This is a double-masked, randomized, crossover study at a single site with a planned enrollment of patients in a series of one-week studies with different combinations of contact lenses and multipurpose solutions.
Researchers evaluated fluorescein staining as well as lens and solution comfort at baseline after 15 minutes of lens wear and at two and four hours of lens wear. The investigators use their own corneal staining scoring system that differs from the aforementioned quantitative scales and also is not comparable to the CCLRU qualitative scales.
The staining score is based on area of staining in each of the five corneal regions. The investigators assessed the percentage of each stained corneal region and averaged the percent area scores for the five regions to give a composite staining value. The average staining levels for the worse eye of each subject are reported. This is a measure of area stained, not a qualitative measure of type or depth of the staining. The researchers planned the pilot study for nine to 14 patients in a two-period crossover study and the other studies for 30 patients each, one a two-period and the other a five-period crossover study.
The staining score of 6 percent with 36 subjects was lowered to 4 percent with 30 subjects. Also in this study, the same care solution formulation marketed under three different brand names returned different outcomes. Different patient populations or, as other studies have noted, discrepancies in inter- and intra-reader repeatability, can produce different results.
We report six previously unpublished studies with Complete MoisturePlus solution and silicone hydrogel lenses Table 2. All were based on recognized staining scales. The researchers conducted slit lamp evaluations at two weeks, one month, two months and three months and at any unscheduled visit. Opti-Free Express solution had ReNu MultiPlus solution had Complete MoisturePlus had Mean corneal staining was 0. Corneal staining was clinically and statistically significantly higher with ReNu MultiPlus than with Focus Aqua at both the two week 1.
The disinfecting agent and preservative for both these solutions is polyhexamethyl biguanide PHMB. PHMB is present in similar amounts in the two solutions, suggesting that other constituents in the formulation play a role in the development of corneal staining. Etiologies of Corneal Staining Corneal staining is linked to many factors, not all of which are contact lens-related, and some of which may represent normal levels of staining in healthy eyes.
Schwallie et al identified corneal staining in healthy eyes of non-contact lens wearers as 0. Dundas et al studied subjects who were non-contact lens wearers or who had no recent contact lens wear. Half of the subjects showed staining in the inferior or superior zones and 5 percent had staining in the central zone. Corneal staining also occurs in successful hydrogel lens wearers and may result from issues other than the care system, including the experimental conditions of the study. Begley and colleagues in Columbus, Ohio conducted a multicenter study with 98 full-time contact lens wearers using different lens care systems and soft contact lenses.
Grading was on the 0 to 4 scale with half-step differences for each of five corneal zones. The average staining grade was 0. Nichols and colleagues examined full-time successful hydrogel contact lens wearers and found corneal staining in at least one eye in Eight percent had moderate to severe staining.
The authors concluded that moderate to severe staining was associated with noncompliance with the care systems, a conventional rather than a planned or disposable lens replacement schedule, and lenses with powers greater than Topically Applied Solutions Fluorescein appears to increase corneal permeability with repeated use, as does the topical anesthetic proparacaine hydrochloride.
Josephson and Caffery looked at five quadrants of the cornea for the presence or absence of corneal staining after sequential instillations of 9mg fluorescein and following administration of proparacaine hydrochloride 0. A single exposure to 9mg of fluorescein resulted in 26 eyes The anesthetic was instilled followed two minutes later by fluorescein.
Of the stained eyes, 10 Of the unstained eyes, 59 Corneal Disease Corneal staining may be a sign of corneal disease and can identify patients who are at risk of developing corneal infiltrates. Papas and colleagues at the Institute for Eye Research in Sydney, Australia, studied subjects over 16 clinical trials using various lens-solution combinations for up to three months.
One out of 10 subjects who had staining had an infiltrate, and subjects who had diffuse punctate staining in at least four of five areas of the cornea were three times more at risk of developing a corneal infiltrative event.
Hydrogen peroxide solutions had low toxic staining rates. Long-term Studies The studies listed above are all short-term. Few studies have looked beyond the first three months of wear to examine persistent staining.
Conclusions Differences in grading scales and study designs make it difficult to compare results across clinical studies. Investigators use different scales to generate corneal staining scores, and these scales are subject to differences in grading precision. A study comparing numerous contact lens and contact lens care solution combinations produced disparate corneal staining results for the same care solution marketed under three different names.
This disparity highlights the need in evaluating clinical study reports to pay attention to the grading systems used, the populations studied, and the consistency of results from several studies. He has over 30 years of ophthalmic industry experience, has given more than 50 professional presentations and published several papers related to contact lenses and refractive surgery.
He holds 14 US patents and has 13 patent applications pending. She graduated from UC Irvine with a degree in Chemistry in
CCLRU GRADING SCALE PDF
The primary reason cited for not using grading scales was a preference for recording clinical data using other means, such as sketches, photographs or written descriptions. Clcru and Efron pictorial, and CCLRU and Vistakon-Synoptik photographic grades of bulbar hyperaemia, palpebral hyperaemia roughness, and corneal staining were analysed. Variability of clinical researchers in contact lens research. Am J Ophthalmol ; Palpebral hyperaemia scale images were well described by colour extraction techniques. Colour extraction has face validity 28 and examines global relative colouration red for hyperaemia and green for staining. Southwest Independent Institutional Review Board, Computerised grading — note the slider at the bottom of the screen allowing easy adjustments of severity.
C42682: Clinical grading scales
In order to improve and standardise anterior eye evaluations between practitioners, subjective grading scales were first popularised back in the mids. Benefits of Grading Scales The benefits of clinical grading scales include accuracy and consistency in clinical record keeping leading to more meaningful communication of clinical cases to fellow health professionals. Clinical grading scales also offer practitioners the most effective way of monitoring the health of an eye wearing a contact lens. They allow for an accurate means of detecting change that can occur during lens use and provide the practitioner with the necessary information to intervene to minimise the risk of a chronic adverse reaction to the contact lens. Table 1 summarises the benefits. Ideally, prior to contact lens wear, the baseline data for a range of clinical variables should be collected and then be continually monitored throughout the course of the patients wearing experience.
Deciphering Corneal Staining Scales