Possible association between subtypes of dry eye disease and seasonal variation

Figures & data

Table 1 Patient characteristics

Diagnostic group	Non-DEDA	DEDA					P-value*
Recruitment season		Spring	Summer	Fall	Winter	Total
Number of patients (n)	1,916	143	143	229	169	684
% male	42.7	18.2	21.7	16.6	21.9	19.3	0.697
Age (years)B	54.4±14.4	54.4±16.5	56.7±15.5	57.6±16.8	54.9±15.1	56.1±18.1	0.219
Median	56	56	58	62	55	57
Range	20–92	20–89	21–88	20–91	20–94	20–94
High myopia (≤−6.00 D) (%)	15.9	14.4	9.6	14.6	17.0	14.0	0.532
Bilateral pseudophakia (%)	7.7	6.3	2.8	8.2	13.2	7.7	0.056
Intraocular pressure (mmHg)B	14.0±3.1	14.5±3.0	14.4±3.0	14.1±2.9	15.4±3.9	14.6±3.2	0.002*
Topical glaucoma medication (%)	7.7	7.0	5.7	8.8	13.9	8.9	0.200
Topical DED medication (%)
Hyaluronate	0	51.7	49.7	50.4	64.6	53.5	0.107
Mucin secretagogue	0	32.9	33.6	39.4	25.7	33.9	0.164
Steroid	0	14.8	16.8	10.2	9.7	12.6	0.245

Notes:

A Classified as DED or non-DED according to the prescription.

B Mean ± SD.

* P<0.05, Kruskal–Wallis test or chi-square test as appropriate for comparing the 4 seasons.

Abbreviation: DED, dry eye disease.

Figure 1 Presence of DED-related symptoms in (A) non-DED and (B) DED patients. Seasonal variation was observed for irritation, pain, blurring, and photophobia in DED patients, with symptoms being most severe in spring. Seasonal variation was also observed in the non-DED subjects, with symptoms being least severe in summer. There was no significant variation in the severity of symptoms between summer, fall, and winter in the non-DED subjects. ^*P<0.05 when the season with the most severe symptoms was compared to the season with the least severe symptoms (chi-square test).

Abbreviation: DED, dry eye disease.

Figure 2 Presence of DED-related signs in (A) non-DED and (B) DED patients. Seasonal variation was observed in BUT and SPK in the DED patients. Seasonal variation in all signs except for the Schirmer test was observed in the non-DED subjects. ^*P<0.05 when the season with the most severe symptoms was compared to the season with the least severe symptoms (chi-square test).

Abbreviations: BUT, tear break-up time; DED, dry eye disease; MBI, maximum blinking interval; SPK, superficial punctuate keratitis.

Table 2 Seasonal variations in DED signs and symptoms

Recruitment season	Non-DEDA	DEDA				Seasonal severity of DED symptoms and signs
		Spring	Summer	Fall	Winter	Least severe	Most severe	P-value*
PDED and DDED	–	71.3 (102/143)	51.0 (73/143)	66.1 (151/229)	70.8 (120/169)	Summer	Spring	0.000
DDED	–	11.2 (16/143)	9.2 (13/143)	12.8 (29/229)	9.4 (16/169)	Summer	Fall	0.104
Signs
SPK (staining score ≥3)	6.1 (117/1,916)	29.4 (42/143)	13.3 (19/143)	15.7 (36/229)	22.2 (36/169)	Summer	Spring	0.001
Schirmer test (≤5 mm)	19.0 (23/122)	17.1 (6/35)	27.9 (17/61)	21.4 (8/39)	41.2 (8/20)	Spring	Winter	0.061
BUT (≤5 s)	42.6 (812/1,907)	73.9 (105/142)	52.4 (75/143)	58.3 (134/229)	63.6 (105/168)	Summer	Spring	0.000
MBI (≤9 s)	25.7 (488/1,900)	30.0 (39/130)	41.5 (59/142)	35.4 (84/229)	35.4 (57/169)	Spring	Summer	0.013
Symptoms
Dryness	21.8 (417/1,915)	42.0 (60/143)	51.0 (73/143)	54.3 (121/223)	52.8 (89/169)	Summer	Fall	0.113
Irritation	13.8 (264/1,911)	37.1 (53/143)	20.3 (28/138)	30.4 (70/229)	24.3 (41/169)	Summer	Spring	0.001
Pain	4.6 (50/1,911)	12.6 (18/143)	7.1 (10/141)	15.4 (35/229)	12.5 (21/169)	Summer	Fall	0.007
Fatigue	28.1 (538/1,915)	47.6 (68/143)	44.1 (63/143)	43.5 (98/225)	54.2 (90/166)	Fall	Winter	0.105
Blurring	14.6 (279/1,911)	38.5 (55/143)	7.2 (10/141)	17.0 (37/218)	28.5 (47/165)	Summer	Spring	0.000
Photophobia	13.9 (266/1,911)	25.2 (36/143)	13.1 (18/137)	21.3 (48/225)	23.6 (40/169)	Summer	Spring	0.007

Notes:

A Prescription-based classification. Data are presented as percentages, with n values (number of positive subjects/number of examined subjects) in parentheses.

* Chi-square test.

Abbreviations: BUT, tear break-up time; DDED, definite DED; DED, dry eye disease; MBI, maximum blinking interval; PDED, probable DED; SPK, superficial punctuate keratitis.