Tear Film Osmolarity of the Eye after Cataract Surgery. Summary of the Doctoral Thesis

Abstract

Almost every cataract surgeon has encountered a situation during the postoperative period when, even though, the primary goal – improvement of visual acuity – has been achieved, yet the patient felt frustrated because of subjective discomfort in the operated eye. Sometimes this issue is more disturbing for the patient than the hope for a perfect visual outcome. Although it has been established that the ocular surface is affected during the postoperative period, there is still no generally accepted opinion about the changes in tear osmolarity after cataract surgery despite several studies dedicated to evaluation of these changes. The present study was designed to elucidate the effect of cataract surgery on the characteristic feature of ocular surface homeostasis – tear film osmolarity in the early postoperative period. Aim. The aim of the study was to evaluate the changes in tear film osmolarity after a cataract surgery in a healthy ocular surface. Methods. For this purpose two examination groups were formed. The study group included voluntary patients undergoing cataract surgery not having any complaints about subjective symptoms typical of dry eye disease. In order to correspond to the criteria of healthy ocular surface, the study group excludes the following types of patients and conditions: contact lens wearers, patients with diabetes, pseudoexfoliation, pterygia and eye drop users. The eye that has not undergone the surgery was classified as the control group. This single–center, prospective study was held at Ophthalmology department of Pauls Stradins Clinical university hospital. All cataract surgeries were done by the same surgeon. The tear osmolarity tests were evaluated with TearLab Osmolarity System (TearLab Corporation, San Diego, CA, the USA) before surgery, in the next morning, one week and one month after the surgery. Results. No statistically significant difference was observed between the groups before operation when comparing the mean tear osmolarity – in the study group it was 296.87 mOsm/L, and in the control group it was 297.27 mOsm/L (p = 0.84). The tear osmolarity results changed significantly during early postoperative period in the study group (p < 0.001), while in non–operated eye no significant tear film osmolarity changes were observed (p = 0.86). Significant changes were recognized on the next day after the surgery – the tears became hypoosmolar (< 275 mOsm/L). One week later the tear osmolarity increased significantly, and the tears became hyperosmolar (312.64 mOsm/L). Over the course of one month, the test values for the study and control groups equalized (297.87 in the study group and 298.93 in the control group (p = 0.66)), when compared to preoperative tear osmolarity results. Conclusion. The results achieved lead towards a more detailed understanding of the changes in the ocular surface homeostasis after a cataract surgery. The obtained data indicate that tear osmolarity changes considerably during the first postoperative month after a cataract surgery. Also, there is a huge difference in measurements between operated and non–operated eye on the next day and one week after the surgery. One month after the surgery tear osmolarity returns to preoperative test results, and there is no difference determined between the eyes.