Assessment Of Parameter Change In Corneal Topography And Oct After Dry Eye Induction

The purpose of the study carried out includes understanding the correlation between epithelial alterations related to dry eye disease using topographic and tomographic maps as a resource. We know that the color scale image in corneal topography can often change with dry eye, but it remains unclear whether this demonstrates changes in keratometric values.

Regarding the thickness of the epithelium, while studies bring the information that with the dry eye the thickness of the epithelium increases  others bring evidence that it decreases  and even do not change, still not having a consensus on this data. 

We propose a study in the form of a single-group pretest-posttest study after induction of dry eye.

The design of the study consisted of performing the corneal topography and the OCT epithelial map in a normal situation and after the simulation of dry eye through prolonged eye opening.  Tomographic measurements were performed using the  Optovue OCT RTVue 100 OCT (Adapt LDTA) and the topography was realized with the TMS-4N Automatic Corneal Topographer (Tomey Corporation, Nagoya Japan).

20 eyes of 10 subjects were enrolled in this prospective, one-group, quasi-experimental pilot study based at the Medicos de Olhos Hospital in Curitiba, Brazil in May 2022.  A complete ophthalmological examination was conducted on all volunteers and the selected volunteers fulfilled the necessary inclusion criteria in the study in addition to completing the consent form.

Continuous variables were reported as either mean ± standard deviation and compared using Wilcoxon Signed-Rank Test. For all tests, we will use 2-sided p-values with an alpha ≤ 0.05 level of significance. The latest available versions of Stata (College Station, TX) were used to conduct all analyses.

The AS-OCT system’s software output produced full corneal thickness as well as epithelium and stroma thickness maps, extending to a 6 3 6-mm corneal area. There was evidence of an increase in the SRI topographic parameter after the induction of dry eye (p=0.0008).

With regard to corneal curvature, there was a statistically significant increase in K2, K1 and ΔK values (p=0.0111, p=0.0418 and p=0.0216, respectively) after dry eye induction. 

Regarding the epithelial thickness, there were statistically significant reduction in values of the central (p=0.0036), minimum (p=0.0036), superior
(p=0.0008) and inferior (p=0.0413) thickness of the epithelium, as well as in the standard deviation of tthe epithelium thickness (p=0.0432).

In conclusion, we show here a quasi-experimental study that evaluated changes in corneal topography and OCT when we induced dry eye. In the topography, we had statistically significant changes in the parameter SRI , K2, K1 and AvK, showing the importance of the topic since these parameters are used for programming cataract and refractive surgery and can directly impact the postoperative result. In OCT, we had a significant decrease in central corneal thickness after dry eye, as well as in several regions of the corneal epithelium. The parameters that showed the most tendency of reduction were, in decreasing order, the parameters of superior, central, minimum and inferior epithelium.