European Journal of Cardiovascular Medicine

Diabetes is a chronic metabolic condition marked by elevated blood glucose levels due to either insufficient insulin production or resistance to insulin, leading to widespread damage to various organs over time^1-3. Type 2 diabetes, the most prevalent form, typically affects adults and involves either insulin resistance or inadequate insulin production, while type 1 diabetes results from a near-total lack of insulin. Diabetes is a multi-organ disease that significantly impacts the eyes, kidneys, heart, blood vessels, and nerves.⁴ Globally, its prevalence has doubled since 1990, with many patients, particularly in low- and middle-income countries, not receiving proper treatment.⁵ In 2021 alone, diabetes directly caused 1.6 million deaths, with nearly half of these occurring in individuals under the age of 70. It is also a major contributor to kidney disease and cardiovascular deaths. Ocular complications are common in diabetic patients, with the disease thickening the retinal vascular basement membrane, leading to pericyte loss and abnormal new blood vessel formation, which can eventually cause blindness.^6,7 Because of this, eye examinations, particularly fundus evaluations, are essential to monitor both ocular and renal health. Beyond diabetic retinopathy and cataracts, dry eye disease (DED), or keratoconjunctivitis sicca, is another prevalent ocular issue among diabetics, affecting over half of diabetic patients. Dry eye disease is characterized by a loss of tear film stability, persistent inflammation, and neurosensory abnormalities, often presenting as burning, itching, redness, photophobia, and foreign body sensation.⁷ The condition is especially common in the elderly and women, making routine screening vital for early diagnosis and intervention. Dry eye is generally categorized into two types: aqueous-deficient and evaporative, although mixed types also exist. Aqueous-deficient dry eye often results from systemic conditions or lacrimal gland dysfunction, while evaporative dry eye is frequently due to lipid layer insufficiency. Diabetes exacerbates dry eye disease through damage to the lacrimal functional unit, Meibomian and goblet cell loss, corneal nerve fiber abnormalities, and reduced blink rates, all contributing to tear film instability and increased evaporation.⁸ Diagnostic tools such as the Ocular Surface Disease Index (OSDI), Tear Film Breakup Time (TBUT), and Schirmer’s test help assess the severity of dry eye. OSDI is a questionnaire evaluating symptom frequency over two to four weeks, categorizing dry eye severity from normal to severe. TBUT measures the interval between a blink and the appearance of dry spots on the cornea, with times under 10 seconds indicating abnormality. Schirmer’s test evaluates tear production by measuring strip wetting after five minutes⁹, with less than 10 mm indicating deficiency. Multiple studies confirm a strong association between type 2 diabetes and higher prevalence of dry eye disease, with severity linked to older age and longer duration of diabetes. Diabetic retinopathy is also correlated with more severe dry eye symptoms. These ocular complications significantly impair patients’ quality of life, affecting physical comfort, social interactions, psychological well-being, and workplace productivity, highlighting the need for regular eye screening in diabetic care.

AIM

To compare the proportion of dry eye disease in diabetics and non-diabetics.

This observational study was conducted over a period of 18 months in the outpatient departments of Ophthalmology and Medicine at Mahatma Gandhi Medical College and Hospital, Sitapura, Jaipur. The study population comprised patients attending these outpatient departments, who were divided into two groups: Group 1 consisted of 102 known cases of diabetes mellitus (DM), and Group 2 included 102 control participants without diabetes. The sample size was determined based on a statistical formula comparing two independent proportions, taking into account an expected 17% difference in the prevalence of dry eye disease between diabetic and non-diabetic individuals. With a power of 80% and a 5% level of significance, the calculated sample size was 102 participants in each group. Inclusion criteria for both groups involved patients of either gender, aged between 18 and 60 years. For the case group, only known diabetics were included, while the control group included non-diabetics within the same age range. Exclusion criteria for both groups included patients with any other ocular surface disease that could cause dry eye (such as pterygium or contact lens use), individuals with systemic causes of dry eye unrelated to diabetes, those unwilling to give informed consent, patients with systemic conditions that prevented proper positioning at the slit lamp, those with a history of ocular surgery, and uncooperative participants.

Table:1 - Distribution of study subject according to Age (N=204)

In this study among the cases 4 (3.9%), 18 (17.6%), 38 (37.3%), 28 (27.5%) and 14 (13.7%) study subjects and among the controls (3.9%), 18 (17.6%), 38 (37.3%), 28 (27.5%) and 14 (13.7%) study subjects belonged to age group < 30, 31 - 40, 41 - 50, 51 - 60 and > 60 yrs. respectively. The mean age of the study subject was 48.04+10.33 yrs. So most of the study subject belonged to age group 41- 50 yrs.

Table: 2- Distribution of study subject according to Co-morbidity (N=204)

Among cases 17 (16.7%) study subject had no co- morbidity except diabetes but 77 (75.5%) and 8 (7.8%) study subjects had hypertension and other co-morbidity respectively. Among controls 52 (51.0%) study subjects had no co-morbidity and rest 45 (44.1%) and 5 (4.9%) study subjects had had hypertension and other co-morbidity respectively.

Table 3: Distribution of study subject according to Symptoms (N=204)

As shown in the table 73(71.6%), 69 (67.6%), 42 (41.2%), 30(29.4%), 61(59.8%) and 29 (28.4%) cases and 41(40.2%), 31(30.4%), 41(40.2%), 28(27.5%), 36(35.3%), 18(17.6%) controls were suffering from redness, burning sensation, stinging sensation, foreign body sensation, pruritus and photophobia in eye respectively.

Table 4: Distribution of study subject according to OSDI Categorization (N=204)

As per OSDI score categorization was done.  Among the cases 18 (17.6%) were not having any dry eye and 22 (21.6%), 46 (45.1%) and 16 (15.7%) were having mild dry, moderate dry eye and severe dry eye respectively. Similarly, among controls 63 (61.8%) were not suffering from dry eye and rest 29 (28.4%), 9 (8.8%) and 1 (0.9%) were having mild dry, moderate dry eye and severe dry eye respectively. So among the diabetic cases number of study subjects with moderate and severe dry eye are more and this difference is statistically significant.(P<0.001)

Table 5: Distribution of Cases and Controls with Dry Eye (Schirmer Test) (n=204)

Among the cases 16 (15.7%) were not suffering from dry eye and 86 (84.3%) were suffering from dry eye. Similarly, among controls 67 (65.7%) were not having dry eye and 35 (34.3%) were having dry eye. So dry was more associated with cases or diabetic patients compared to controls and this difference was statistically significant. (p<0.001)

Table 6: Distribution of study subject according to TBUT (n=204)

As shown in the table on doing TBUT test it was found that among the cases 19 (18.6%) were not suffering from dry eye disease and 68 (66.7%) were suffering from mild to moderate and 15 (14.7%) were suffering from severe dry eye disease. Among controls 63(61.8%) were not suffering from any dry eye disease and 35(34.3%) were suffering from mild to moderate dry eye disease and 4(3.9%) were suffering from severe dry eye disease. So among diabetics mild to moderate and severe dry eye was more prevalent and this difference was statistically significant. (p<0.001)

Dry eye disease is a complex ocular surface disorder in which there are symptoms of sensation of a foreign body, burning, stinging, redness, itching, and photophobia and may be due to hemostasis disturbance of the tear film, persistent inflammation, hyperosmolarity etc.¹ .   Hyperglycemia in diabetes may affect the lacrimal functional unit, Meibomian gland epithelial cells and goblet cells, corneal nerve fibers etc. leading to irregular blinking, deficient tear film, autonomic neuropathy etc.^10,11

In this study the prevalence of dry eye was compared among 102 diabetic cases and 102 non diabetic controls using Ocular surface disease index (OSDI) questionnaire followed by Tear film breakup time test (TBUT) and Schirmer test. 8

 The mean age of the study subject was 48.04+10.33 yrs.  In this study among the cases 4 (3.9%), 18 (17.6%), 38 (37.3%), 28 (27.5%) and 14 (13.7%) study subjects and among

the controls (3.9%), 18 (17.6%), 38 (37.3%), 28 (27.5%) and 14 (13.7%) study subjects belonged to age group < 30, 31 - 40, 41 - 50, 51 - 60 and > 60 yrs. respectively. Most of the study subject belonged to age group 41- 50 yrs. followed by 51 to 60 yrs. Mangoli et all¹²(2023) in a cross-sectional study done in southern India found that  out of total 200 subjects  (100 diabetic and 100 non diabetic ) the mean age was  55.02 ± 12.21 years which is quite similar to our study (48.04+10.33 yrs.) . The higher mean age could be explained due to fact higher number of type 2 diabetes in all these studies

In this study 114 (55.9%) study subjects were suffering from redness, 100 (49.0%) from burning sensation, 83 (40.7%) from stinging sensation, 58(28.4%) from foreign body sensation, 97 (47.5%) from pruritus and 47 23.0%) study subjects were suffering from photophobia in eye respectively. Raman et all¹³  (2021) in their similar study reported that among the study subject itching and grittiness were the most common symptoms and amongst diabetics, grittiness was  the predominant symptom being seen in 58.3% patients. Itching (62.5%) and foreign body sensation (54.2%) were the most common symptoms in patients with no history of diabetes.

In our study the dry eye was detected among study subjects using OSDI score and TBUT test and study subjects were labelled as having dry eye by doing Schirmer Test. The mean OSDI score of the study subject was 15.11205. As per OSDI score 81(39.7%) 51 (25%) 55 (26.9%) and 17 (8.3%) were categorized as having no dry eye, mild dry eye, moderate dry eye and severe dry eye respectively. So a total of 123 (60.3%) were suffering from dry eye as per OSDI score. Now we categorized the cases and control according to OSDI category and found that among the cases 63 (61.8%) were not having any dry eye and were having mild dry, moderate dry eye and severe dry eye respectively. Similarly, among controls 29 (28.4%) were not suffering from dry eye and rest 29 (28.4%), 9 (8.8%) and 1 (0.9%) were having mild dry, moderate dry eye and severe dry eye respectively. So among the controls the number of study subjects with moderate and severe dry eye are more and this difference was statistically significant. (P<0.001) Bashorun et all¹⁴ (2024) studied 100 type 2 diabetes  cases and 99 non diabetic controls and applied SPEED questionnaire which showed that out of 197 participants, 172 (87.31%) reported one or more symptoms of DED while OSDI questionnaire found Dry eye in 157 (76.96) in our study which showed nearly same prevalence . But the study found that the proportion of severe DED symptoms were significantly higher in the nondiabetic group (30.61%) compared to the diabetic group (14.14%) with a proportion difference of 16.47% and a P value of 0.006. In contrast, in our study we found that as per OSDI score moderate (46 (45.1%)) and severe dry eye (16 (15.7%) was more prevalent in diabetic subjects compared to controls and that difference was highly statistically significant. It stressed upon the fact that diabetes is a risk factor for the dry eye disease.

Now in our study Schirmer test was done on a total 204 study subjects. Cases and controls were categorized as per Schirmer test and it was found that among the cases 86 (84.3%) out of 102 were suffering from dry eye and among controls 35 (34.3%) out of 102 were having dry eye. So dry was more associated with cases or diabetic patients compared to controls and this difference was statistically significant. (p<0.001).

On doing TBUT test Among cases it was found that 68 (66.7%) were suffering from mild to moderate and 15 (14.7%) were suffering from severe dry eye disease and among controls 35 (34.3%) were suffering from mild to moderate dry eye disease and 4 (3.9%) were suffering from severe dry eye disease as per TBUT test. So among diabetics mild to moderate and severe dry eye was more prevalent compared to non-diabetic and this difference was statistically significant. (p<0.001) Lamba et all¹⁵(2023) in a similar study used Tear breakup time (TBUT) to determine dry eyes disease and found that majority of participants had moderate DED 50 (25.0%); seen in Diabetic patients 27 (27.0%) and nondiabetic population 23 (23.0%). Even the risk of DED increased among diabetic patients after adjustment for other variables and the risk of DED was 8.08 times more likely among Diabetic patients than non-diabetic patients. We also did a TBUT test and found that compared to controls among cases 48 (57.1%) were suffering from mild to moderate and 16 (19.0%) were suffering from severe dry eye disease and this difference was statistically significant. (p<0.001).

This study found a significantly higher prevalence of dry eye disease among diabetic patients compared to non-diabetic controls. Diabetics experienced more moderate to severe dry eye symptoms, as confirmed by OSDI scores, Schirmer test, and TBUT results. Common symptoms included redness, burning, and itching, with statistically significant differences across all diagnostic parameters. The findings support that diabetes, particularly type 2, is a major risk factor for dry eye disease. Regular screening and early intervention for dry eye in diabetic patients is therefore strongly recommended.

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