Abstract
Purpose:
To analyze the relationship among patient`s symptoms, the stability of the pre-corneal film as assessed by anterior segment OCT, and the "common" lacrimal tests such as: Schirmer`s test 1, tear break-up time (TBUT), and ocular surface staining.
Methods:
We examined a sample of 30 patients referred for dry eye symptoms by means of McMonnies questionnaire, Schirmer`s test 1, TBUT, Oxford scheme for grading ocular surface staining. Tthe dynamic distribution of the pre-corneal film was studied by using anterior segment OCT (Carl Zeiss Meditec Cirrus HD OCT), and it was quantitatively evaluated on the appearance of a double line of the tear film. OCT examination was performed before and after the instillation of artificial tears up to the 5th minute. The kappa statistic was used to assess the agreement between tests. All examinations were conducted in the same conditions of temperature, brightness, humidity and time of the day.
Results:
Our population of dry-eye patients showed 3 levels of severity on the basis of subjective symptoms: mild, intermediate and severe. A good association was shown between these 3 levels of symptoms and the OCT pattern of dynamic distribution of the pre-corneal film: the tear film double line was reduced in height (Sperman's rho = 0.83; p=0.005), and the tear film showed a reduced residence-time on the corneal surface (Sperman's rho = 0.65; p=0.01). This association between subjective patient`s symptoms and OCT pattern of the pre-corneal film was observed also in cases where the results of the "common" objective tests resulted normal (kappa=0.78, p=0.03).
Conclusions:
The analysis by anterior segment OCT of the pre-corneal film can reveal abnormalities of the dynamic pattern of tears that may explain the patient's symptoms, even when the common lacrimal tests appear to be normal. The dynamic pattern of tears on the cornea is most likely due to the adhesive properties of the ocular surface that cannot be investigated by classical tests.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
486 cornea: tears/tear film/dry eye •
479 cornea: clinical science