Objective To investigate the influence of undercorrected orthokeratology on myopia control, and the correlation between target and central corneal epithelial damage. Methods A retrospective study was conducted on 22 undercorrected orthokeratology lens wearers (37 eyes) from January 2016 to February 2017, and 25 full corrected wearers (47 eyes) during the concurrent period were randomly selected as the control group. The changes of axial length before and after orthokeratology lens wearing and the within-6-month central corneal epithelial damage after orthokeratology lens wearing were analyzed. Results The average annual increase of axial length was (0.13±0.15) mm in the undercorrected group, and (0.14±0.16) mm in the full corrected group, the difference was not statistically significant (P>0.05). Multiple linear regression analysis showed that there was no correlation between the axial growth and the undercorrection of the target (P>0.05), but a negative correlation between the axial growth and the age (P<0.01). After using orthokeratology, the average annual growth of the axial length in children aged 7-10 years was (0.25±0.16) mm, and (0.10±0.14) mm in children aged 11-15 years, the difference was statistically significant (P<0.01). The incidence of central corneal epithelial punctate staining in the (–4.25)-(–5.00) D target group was 27.08%, and that in the (–3.00)-(–4.00) D target group was 16.67%, the difference was not statistically significant (P>0.05). Conclusions The effect of orthokeratology on myopia growth is not affected by the undercorrected target, not related to the undercorrection of target, but negatively correlated with the age. Undercorrected orthokeratology can still be used for myopia control in high myopia patients. No correlation is found between the target and central corneal staining.
ObjectiveTo investigate whether the corneal shape recovered after discontinuation of long-term orthokeratology and whether orthokeratology increased the corneal astigmatism and ocular astigmatism.MethodsFrom December 2016 to April 2018, a retrospective study was conducted on 33 myopic patients who had undergone two times standard orthokeratology in the outpatient department of West China Hospital of Sichuan University, and had stopped wearing the first orthokeratology lens for one month before fitting the second orthokeratology lens. A total of 32 myopia frame glasses wearers were selected by simple random sampling as control. The changes of corneal flat meridian curvature (flat K), corneal steep meridian curvature (steep K), corneal astigmatism and ocular astigmatism before and after discontinuation of orthokeratology were analyzed.ResultsAmong the patients with baseline myopia diopter of −0.25～−2.75 D, the average annual change of corneal flat K was (−0.03±0.21) D in the frame glasses group and (−0.24±0.14) D in the orthokeratology group, the difference was statistically significant (t=5.555, P<0.001). Among the patients with baseline myopia diopter of −0.25～−2.75 D, the average annual change of corneal steep K was (0.20±0.42) D in the frame glasses group and (0.15±0.20) D in the orthokeratology group, the difference was not statistically significant (t=0.785, P=0.435). Among the patients with baseline myopia diopter of −3.00～−5.75 D, the average annual change of corneal steep K was (0.29±0.39) D in the frame glasses group and (−0.01±0.20) D in the orthokeratology group, the difference was statistically significant (t=2.758, P=0.014). The average changes of corneal astigmatism were analyzed according to the difference of eyes, gender, age and baseline corneal astigmatism, the difference was not statistically significant (P>0.05), respectively. For patients with baseline astigmatism absolute value less than or equal to 0.50 D, the astigmatism annual change of the frame glasses group was 0.00 (0.50) D, and that of orthokeratology group was −0.33 (0.48) D, the difference was statistically significant (Z=−2.301, P=0.021).ConclusionsThe flat K of the cornea becomes flatter and the steep K does not change after one month’s discontinuation of long-term orthokeratology. There was no difference in the increase of corneal astigmatism compared with those wearing frame glasses. When the baseline ocular astigmatism is less than or equal to 0.50 D, the increase of astigmatism may occur after discontinuation of orthokeratology.
Objective To explore the application effect of virtual reality (VR) technology in low vision teaching for optometry students. Methods Undergraduate students majoring in optometry at West China School of Medicine of Sichuan University were selected as the research subjects. The students enrolled in 2020 adopted the traditional lecture-based learning (LBL) teaching mode (LBL teaching group), while the students enrolled in 2021 adopted the VR teaching mode (VR teaching group). Both groups of students had studied the content of the same chapter on low vision, completed in class tests after learning, and completed a questionnaire survey. Results There were 28 students in the VR teaching group and 30 students in the LBL teaching group. There was no statistically significant difference in age and gender composition between the two groups of students (P>0.05). The in-class test scores of students in the VR teaching group were higher than those in the LBL teaching group [86.43±6.10 vs. 78.10±7.69, P<0.05)]. Except for “subjective discomfort with this teaching mode”, the differences in other evaluation results between the two groups were statistically significant (P<0.05). VR teaching group students generally believed that applying VR technology to low vision teaching helped understand the visual experience and daily life status of low vision patients, improved learning efficiency and hands-on ability, reduced learning burden, and hoped to use this teaching mode routinely in other subject teaching. All students in the VR teaching group believed that this teaching mode was interesting, highly innovative, and enhanced teacher-student interaction.Conclusions Applying VR technology to low vision teaching can enable students to personally experience the impact of various diseases on patients’ visual function and daily life. This teaching method not only optimizes and improves teaching effectiveness, but also has a high acceptance rate among students, which is worth further promoting in future optometry teaching.