Al-Basar International Journal of Ophthalmology

: 2020  |  Volume : 7  |  Issue : 1  |  Page : 4--10

Tear film assessment in sudanese diabetic patients attending Jabir Abu Eliz Diabetic Center, Khartoum, Sudan

Saeeda Mohammed Osman, Mahgoub Saleem 
 Department of Ophthalmology, Faculty of Medicine, Al-Neelain University, Khartoum, Sudan

Correspondence Address:
Prof. Mahgoub Saleem
Department of Ophthalmology, Faculty of Medicine, Al-Neelain University, P.O. Box: 10139, Khartoum 11111


Background: Several local and systemic conditions predispose the eye to the development of dry eye disorders due to tear film dysfunction, which is presented in variable degrees of eye irritations and inflammation. Diabetes mellitus (DM) is among the most common risk factors of dry eye disease (DED). It is more common in older females than males. Tear film assessment can be tested with some simple tests such as Schirmer's test (ST), fluorescein strip (FS) (breakup time [BUT]) test, and lissamine green strip (LGS) test. Objective: The aim of this study is to assess the tear film dysfunction in diabetic patients with ST, FS papers, and LGS papers and compare their diagnostic values. Materials and Methods: In a cross-sectional hospital-based study, consecutive 126 diabetic patients were examined at Jabir Abu Eliz Diabetic Center in Khartoum for their tear film dysfunction. All selected patients had simultaneously undergone ST, FS (BUT) test, and LGS test in the same order and equal definite intervals in all patients over a 2-month period (September 1, 2013–November 1, 2013). Clinical and personal information was obtained by direct patients and chart review before complete ophthalmic examinations. Results: The mean age of the study group was 53 ± 12.1 years (30–78 years). Fifty-seven patients (45.2%) were female and 69 (54.8%) were male. In the age group, 11 (8.7%) patients were of type I DM, whereas 115 (91.3%) of type II DM. Forty-four (34.9%) patients had good DM control and 82 (65.1%) had poor DM control. The ST results of the current study demonstrated the presence of 142 patients (56.3%) in the “normal Schirmer's grade,” 49 patients (19.4%) in “mild-to-moderate Schirmer's grade,” and 61 patients (24.2%) in “severe Schirmer's grade.” In the BUT “FS” test, 165 patients (65.5%) gave normal results, whereas 87 patients (34.5%) showed severe tear dysfunction results, with a highly significant difference with P = 0.001. Whereas, in the LGS test, 201 patients (79.8%) were of “normal grade” results and 51 patients (20.2%) were “mild-to-moderate” grade. Conclusion: DED is an important feature of poorly controlled DM, which can be easily detected by performing a variety of simple quick tests such as the ST, fluorescein tear BUT test, and LGS test. There is notable variation among these three tears; therefore, a combination of any two tests is necessary. There is a strong correlation between qualities of the DM control, duration of DM, and severity of DED.

How to cite this article:
Osman SM, Saleem M. Tear film assessment in sudanese diabetic patients attending Jabir Abu Eliz Diabetic Center, Khartoum, Sudan.Albasar Int J Ophthalmol 2020;7:4-10

How to cite this URL:
Osman SM, Saleem M. Tear film assessment in sudanese diabetic patients attending Jabir Abu Eliz Diabetic Center, Khartoum, Sudan. Albasar Int J Ophthalmol [serial online] 2020 [cited 2023 Mar 31 ];7:4-10
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Dry eye disease (DED) is defined by the International Dry Eye WorkShop (2007) as a multifactorial disease of tears and ocular surface that may result in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface.[1] It is a common global clinical disorder which tends to affect up to 35% of normal adults among the general population.[2],[3] The prevalence of DED in community-based studies[4] was found to be lower than in hospital-based studies. The prevalence of DED in diabetics may exceed 50%.[5],[6],[7] Since diabetic patients, especially with poor metabolic control, were more likely to present with DED due to their decreased tear film stability,[8] dry eye tests should be added to the routine screening of diabetes. Females may report a high incidence of DED than males.[9] There is a progressive decline in tear production in older adults due to age-related changes in the lacrimal gland.[10],[11] Tear film assessment can be tested with some simple tests which can be done in the clinics, such as Schirmer's test (ST), fluorescein strip (FS) (breakup time ([BUT]) test, and lissamine green strip (LGS) test: (1) ST: Clinically, it is the most common with well-defined “Schirmer scores.” Schirmer I measures total tear secretion: basal and reflex. Schirmer II measures only the reflex and not the basal secretion.[12] The use of topical anesthetic with the test is very controversial.[13] (2) FS: It is also known as “tear film BUT test (BUT or TF-BUT)” performed using FSs under the cobalt blue filter on slit lamp, BUT; the test was considered to be “positive for dry eyes” if the BUT was <10 s.[14] (3) LGS: LGS is an “epithelial staining” dye like the Rose Bengal (RB) but causes no pain, discomfort, or corneal toxicity that is associated with RB. The LGSs were placed into the lower fornix to stain the cornea blue by causing blue corneal speckling (dot formation) under very low slit-lamp illumination with white light.[15],[16] LGS test recommended grades as normal, mild, moderate, and pathological[16] at minimum of 4 points to be adopted.[15],[17] LG dye is indirectly ascertaining the presence of reduced tear volume by the detection of damaged epithelial cells, as LG dye is taken up by the dead or dying cells of the corneal epithelium.[18] It is less sensitive and more transient, and very difficult to be appreciated on slit lamp,[19],[20] so advisable to be done in a combination of another test as FS.

 Materials and Methods

In a hospital-based cross-sectional descriptive study, consecutive 126 patients (252 eyes) referred to the Department of Ophthalmology at Jabir Abu Eliz Diabetic Center (JDC), with a diagnosis of type I or type II diabetes mellitus (DM), were included in this study. Tear film assessment was tested with ST, FS (BUT) test, and LGS test. All selected patients had simultaneously undergone the three tests: ST, FS (BUT) test, and LGS test in the same order and equal definite intervals in all patients. The study was done over 2-month period (September 1, 2013–November 1, 2013). Clinical and personal information was obtained by direct patients and chart review before complete ophthalmic examinations. Exclusion criteria were determined by the presence of ocular or systemic pathologies that are lead to dry eye syndrome (DES) including idiopathic, contact lenses, trauma, eye surgeries, collagen vascular diseases, and drugs.

The same identical structured methods of the following three tests (ST, FS (BUT) test, and LGS test) were done for each eye and each participant in the whole study group, as “one eye at a time.”

The Schirmer's test (ST) was done with 'TearFlo' Schirmer paper strips (manufactured by: HUB Pharmaceuticals, LLC (USA). 100); 6617 N Scottsdale Road, Suite 204, Scottsdale, AZ 85250 [email protected]); the test was done “one eye at a time” without topical anesthesia, after reassuring the patients. The eyes were gently dried of excess tears from the inferior fornix with filter or tissue papers. Then, the folded end was inserted at the junction of the middle and outer thirds of the lower lid taking care not to touch the cornea or lashes, and the patient was asked to keep the eyes gently closed. After 5 min, the filter paper was to be removed and the amount of wetting was measured from the folded region. The reading of “less than 10 mm” of the wetting portion after 5 min without anesthesia was to be considered as “a positive ST.” We adopted the grading of Kanski and Bowling,[21] in which the ST was distributed in three grades: normal for more than 10 mm, mild to moderate between 6 and 10 mm, and severe for <5 mm (positive ST for dry eye wetting of the paper after 5 min.

Fluorescein strips (breakup time)

TF-BUT test (BUT) measurement was performed using FSs by (Fluorets®, Chauvin Pharmaceuticals Ltd., Surrey, UK). The FS was introduced gently in the lower fornix, in the lower conjunctival sac, “one eye at a time.” Then, the patient was asked to blink several times and then to keep the eyes open. Corneas were examined under cobalt blue filter on slit lamp (Haag-Streit Diagnostics-Slit Lamp BQ 900/870 18./2014 – 11; Haag-Streit AG Gartenstadtstrasse 10 3098 Koeniz, Switzerland,, whereas the dry areas were indicated by the presence of a black spot. The time between the last blink and the appearance of a random dry spot was recorded in seconds by stopwatch as BUT. There are scaling grades in the BUT. A positive test for dry eyes was taken when BUT was <10 s, as the normal time for tear film breakup is 15–20 sA.

Lissamine green strips

Tear production was measured by LGS dye-impregnated paper strips (Green Glo™ lissamine green [LG] in 10 sterile strip packs). The LGSs were wetted with drops of sterile saline and then placed into the lower fornix, in the conjunctival sac with minimal stimulation of the eye, “one eye at a time and for 1 min.” Patients were asked to blink gently to allow adequate corneal and conjunctival staining. Blue corneal speckling (dot formation) to detect dry patches as well as any muco-deficient or damaged cells was detected under very low illumination with white light of the slit lamp. In the LGS test, we adopted the recommended LG grades: normal for Grade 0–1 and mild to moderate for Grades 2–6, which was to be read on the cornea and palpebral conjunctiva (nasal and temporal palpebral conjunctiva): 1 point for few spots, 2 points for several separate spots, and 3 points for conflurative spots. A maximum of 9 points can be reached. The test is pathological at minimum 4 points.

Ethical considerations

Ethical approval was obtained from the Ministry of Health. Informed consent was obtained from each patient, and they were reassured that their data will be kept in confidentiality.


Tear film dysfunction was assessed in 126 diabetic patients (252 eyes) at JDC, Khartoum. The mean age of the study group was 53 ± 12.1 years (30–78 years). Sixty-nine patients (54.8%) were male and 57 (45.2%) were female [Figure 1] and [Table 1].{Figure 1}{Table 1}

In the distribution of patient's groups, there were 7 patients (5.6%) below 30 years of age (6 women [4.8%] and 1 man [0.8%]), there were 41 patients (32.5%) in the age group of 30–50 years (23 females [18.3%] and 18 males [14.3%]), and there were 78 patients (61.9%) in the >50 years' age group (28 females [22.2%] and 50 males [39.7%]) [Figure 2] and [Table 1].{Figure 2}

The majority of the study population were of DM II (115; 91.3%), whereas only 11 patients were of DM I (8.7%) [Figure 3]. Regarding the distribution of diabetes type according to age group, 7 (5.6%) patients in the age group below 30 years were of DM I and no DM II, whereas in the 30–50 years' age group, 4 patients (3.2%) of DM I and 37 patients (29.4%) of DM II. All the 78 (62%) patients in the age group >50 years were of DM II [Figure 4] and [Table 2].{Figure 3}{Figure 4}{Table 2}

In the current study, there was a correlation between qualities of the DM control and the duration of DM. Those with good control with their DM duration <5 years were 18 patients (14.3%), and 21 patients (16.7%) had poor DM control. Those with good control with their DM duration <5 years were 18 patients (14.3%), and 21 patients (16.7%) had poor DM control. While in those with their DM duration between 5-10; 8 (6.4%) of them had good DM control and 19 (15.1%) had poor DM control. On the other hand; patients who were more than 10 year's DM duration; 18 (14.3%) of them had good DM control and 42 (33.3%) had poor DM control. Therefore, in this study group, almost the number of patients with poor DM control (82, 65.1%) was double that of those with good control (44, 34.9%) [Table 3].{Table 3}

In the current study, the basal and reflex tear function measured by the ST revealed that 142 eyes of 71 patients scored normal tear production of 56.3% in the “normal Schirmer's grade.” The total “abnormal tear production” detected by the same ST scored 43.7% (19.1 as mild to moderate + 24.6% as severe), which means that there was a significant reduction in the basal and reflex tear secretion among the currently studied diabetics (43.7%) [Table 4]. This ST abnormal tear production score was lower than BUT scores and higher than LGSs [Figure 5] and [Figure 6].{Figure 5}{Figure 6}{Table 4}

The TF-BUT test (BUT) results in 164 eyes of 82 patients [Table 4] were very deferent from the other two tests, as the BUT normal tear production was 34.9%, being the lowest normal scores when compared by ST and LGS results [Figure 5] and [Figure 6]. In the meantime, the abnormal tear production of BUT (only as severe, no mild-to-moderate grade) scored almost double (65.1%) that of the normal tear production of the same “BUT” test, showing severe tear dysfunction result, with a highly significant difference with P = 0.001. Hence, BUT seems to detect DED better than the other two tests.

The LGS test (LGS) results in 200 eyes of 100 patients [Table 4] scored the highest normal tear production (79.4%) and the lowest abnormal (only as mild-to-moderate grade, no severe) tear production (20.6%) [Figure 5]. LGS seems to be the least in detecting DED as compared with ST and BUT [Figure 5] and [Figure 6].

The results of the three tear production tests show highly significant differences between them (P = 0.001). In general, the average reading of the normal tear production of the three tests was 56.9% and the average of the abnormal tear production of the three tests was 43.1% in a ratio of almost 3:2 [Figure 7].{Figure 7}


DED (DES) is a common disorder of tear film due to tear deficiency or excessive tear evaporation. This leads to the damage of the interpalpebral ocular surface, which causes distressing sore eyes symptoms.[22],[23] Early diagnosis and timely treatment are essential to avoid serious complications secondary to inevitable microbial corneal infection and ulceration.[24] Diabetic patients suffer tear dysfunction more than nondiabetics because of their variable degrees of peripheral corneal neuropathy.[25] This serious ocular surface disorder could be confirmed by performing a variety of simple quick tear film production tests, especially for diabetic patients.[26],[27] It is advisable in diabetics, even without subjective symptoms of dry eye to do multiple tear film tests, to assess the exact degree of the diabetic DES, as some tests have more diagnostic values in certain patients than others.[26] There is no one test that can assess the ocular tear film alone, as each test with others can give satisfactory results. Impression cytology can be the ideal method, but it is a long invasive process that required laboratory help.[28],[29]

In the current study, the ST results revealed that 43.7% of the current diabetic patients scored a significant “positive ST,” which indicates a significant reduction in basal and reflex tear secretion among these diabetics. In another way, 43.7% of these diabetics with “positive ST,” and they have an “abnormal tear production” or tear film dysfunction, so they are possible candidates for full-blown DED. The current study results were in alignment with the result obtained by Saito and colleagues (Korea; 2003) [30] who revealed that the basal and reflex tear secretion was significantly reduced. Also, Martin Geobbels in University Eye Hospital of Bonn, Germany (2000) [31] demonstrated that the majority of diabetics; specially insulin dependent, showed distinct signs of conjunctival surface disease due to reduced tear secretion.

In the present work, BUT was significantly reduced; 65.1% had “positive test” for tear dysfunction and only 34.9% had normal tear function (normal >10 min). This study was agreed with many other international studies in deferent places like West China Hospital study by Yu et al. in a multitest study, including BUT, ST, epithelial staining tests, and others[32] which concluded that tear film dysfunction was high in diabetic patients. Idu and Oghre from the University of Benin (2010) reported “abnormal tear production” detected by the ST and BUT tests, especially with poorly controlled type II diabetics (DM II); however, it was not statistically significant (P > 0.05).[33] Dogru et al. from Japan (2001) had the same impressions and results.[34] Ozemir et al. in Turkey (2003) attributed the ocular surface disorders and tear dysfunction in patients with type 2 diabetes to poor metabolic control and severity of proliferative diabetic retinopathy.[35]

Hence, the positive results of reduced tear film stability in the current study were supported by the above international similar studies. All of them reported positive results that indicate decreased tear production in diabetics, especially with long duration,[34] poor metabolic control, and severe microvascular complications (proliferative diabetic retinopathy).[35] Misra et al. in New Zealand National Eye Centre suggest that ocular surface abnormalities may occur in parallel with diabetic peripheral neuropathy as tear film stability was inversely associated with total body neuropathy score.[36]

LG vital stain (LG) test in the present study demonstrated a very unusual low “positive” results as compared with the ST and BUT tests; it was 4 times less (20.2%) than the result of normal tear's function (79.8%). As far as we searched the literature, no similar result was found. Even though, a lot of explanations may support this LG low positive results: Some researchers like Najafi et al. (Tehran, Iran, 2015) commented about the less accuracy of LG staining as compared with the other tear's function tests (ST and BUT).[37] Delaveris et al.[38] in Sydney, Australia, demonstrated significant differences in LG staining intensity from different companies; staining was significantly higher with some LG brands and lower in others that may underestimate the presence of DED. These variations may be one of the causes of this study “very unusual low positive results.”[38]

LG demonstrates conjunctival staining rather than corneal staining,[15] but the ocular surface staining is commonly employed as an outcome measurement of corneal and conjunctival staining, according to Oxford Scheme for grading ocular surface staining in dry eye conditions.[39] Therefore, the ocular surface area in LG staining will be less than the actual ocular surface area needed for final results. Ramsey suggested that, in an article published in April 2011 in the journal of “Review of Cornea and Contact lenses,” the use of these vital stains in practice should be in combination rather than alone, for example, LG + FS.[40] Bunya et al. (2012–2016)[41] developed semi-automated quantification of LG test of the bulbar conjunctiva from digital images but still not for a commercial use. This new technology may improve the quality of LG score for tear production assessment in the future.[41]


Tear film dysfunction and ]DED is an important feature of poorly controlled DM, which can be easily detected by performing a variety of simple quick tests such as the ST, fluorescein tear BUT test, and LGS test. BUT test demonstrated the highest sensitivity in detecting the tear dysfunction, whereas LGS test produces the lowest positive tear production and seems to be the least in detecting DED as compared with fluorescein test and BUT. There is notable variation among the three tear production diagnostic tests (ST, BUT test, and LGS test). Therefore, the best test is a combination of any two tests. There is a strong correlation between qualities of the DM control, duration of DM, and severity of tear film dysfunction.


A detailed ocular surface evaluation is recommended for all diabetic patients to detect early evidence of ocular surface disorders, DED, as prompt treatment prevents future vision-threatening complications. BUT test demonstrated a high sensitivity as compared to other tests, and it should be used as an initial screening tool in outpatient departments to detect early tear film instability in diabetics. The best test results can be obtained by combination at least two tests including BUT.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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