Effect of dry eye on the reliability of keratometry for cataract surgery planning

This study aimed to evaluate the effects of dry eye on the reproducibility of keratometry (K) measurements in patients presenting for cataract surgery.A non-randomized controlled clinical study was performed. Eighty-three eyes of eighty-three patients with cataracts who were enrolled in our hospital from March 2020 to July 2020 were studied. The mean non-invasive tear film break-up time (NIBUT), corneal fluorescein staining score, and ocular surface disease (OSD) SPEED II questionnaire were measured and recorded prior to surgery, and the patients were assigned to a "dry eye" group (n=35) or a "non-dry eye" group (n=48). The K of the patients was measured twice by a Tomey OA-2000 (an average of three times each). The difference of the mean K (ΔKm) and astigmatism vector (ΔKvector) between the two measurements was calculated. The ΔKm and ΔKvector between the two groups were compared. The relationship between the measurement parameters of dry eyes and the accuracy of the preoperative K values was analyzed.ΔKm was 0.09 D [0.03; 0.19] in the non-dry eye control group and 0.28 D [0.18; 0.50] in the dry eye group, with a statistical difference between the two groups (P=0.005). The ΔKvector of the non-dry eye control group was 0.22 D [0.14; 0.42], and that of the dry eye group was 0.50 D [0.28; 1.06]. There was a significant difference between the two groups (P=0.010). Between the two groups, the percentage of the ΔKm and ΔKvector values greater than 0.5 D were statistically different (P<0.05). There was no significant difference in ΔKm between the groups with NIBUT>5s and NIBUT≤5s (P=0.537). There was no significant difference in ΔKm between groups≥2 and<2 on the OSD SPEED II questionnaire scores (P=0.442).Dry eye can affect the reliability of keratometry measurements before cataract surgery, thereby affecting the accuracy of intraocular lens power calculations. In cataract surgery planning, it is necessary to detect subjective and objective indicators of dry eye in patients and carry out effective intervention so as to avoid refractive errors caused by inaccurate keratometry measurements.