RESUMO
AIM: To compare the changes in axial length of myopic patients of different ages after wearing orthokeratology lenses with increased compression factor(ICF)or conventional compression factor(CCF)for 2 a.METHODS: Retrospective study. A total of 141 myopia patients(141 right eyes)aged 8 to 15 years who fitted with orthokeratology lenses in the General Hospital of Foshan Aier Eye Hospital from July 2020 to July 2021 were continuously included. They were divided into the CCF group(70 cases, 70 eyes)and the ICF group(71 cases, 71 eyes). The patients in the CCF group were fitted with orthokeratology lens of 0.75 DS CCF, while patients in the ICF group were fitted with orthokeratology lens of 1.25 D ICF. Taking 12 years old as a boundary, these two groups were divided into 8-11 years old and 12-15 years old group. The uncorrected visual acuity(UCVA), horizontal corneal curvature(K1)and corneal staining were recorded for all subjects after wearing lenses for 1 d, 1 wk, 1, 6 mo, 1 and 2 a. The axial length(AL)was recorded after wearing lenses for 6 mo, 1 and 2 a, and the complication and corneal epithelial staining were observed during lens wearing.RESULTS:The improvement of UCVA in the ICF group was faster than that in the CCF group, which were statistical significant after wearing lenses for 1 d, 1 wk and 1 mo, respectively(all P<0.001); however, there was no statistical significance between the two groups after 6 mo, 1 and 2 a(all P>0.05); K1 of the ICF group decreased faster than that of the CCF group, and there were statistical significance at 1 d, 1 wk, and 1 mo after wearing lenses(all P<0.05); there was no statistical significance at 6 mo, 1 and 2 a(all P>0.05). The axial length growth of patients aged 8-11 years old in the ICF group and CCF group was 0.35±0.17 and 0.48±0.26 mm, respectively(P=0.010), after wearing lenses for 2 a, and the axial length growth of patients aged 12-15 years old in the ICF group and CCF group was 0.16±0.15 and 0.31±0.29 mm, respectively(P=0.011). During the follow-up period, corneal spotting occurred in 6 eyes(8.5%)in the ICF group, and 7 eyes(10%)in the CCF group(P>0.05), all of which were grade 1 spotting.CONCLUSION:Wearing ICF orthokeratology lens is more effective than wearing CCF lenses in controlling the growth of axial length, with faster shaping and more obvious improvement in UCVA, especially for the prevention of high myopia in children under 12 years. Therefore, young children can give priority to wearing lenses that increase the compression factor, and for children over 12 years old, the compression factor of the lens can be selectively increased according to the wearer's eye habits, health status of ocular surface and visual function.
RESUMO
In the volume-cycled ventilator, the actual tidal volume delivered to the patient is influenced by the compression volume and elasticity of the circuit. The purpose of the present study is to compare the set tidal volume with the measured tidal volume, and calculate the compression factor of the ventilator. We studied twenty pediatric patients weighting above 10 kg. The set tidal volume ( V(r)), the exhaled volume displayed in the ventilator ( V(exh)) and the actual tidal volume measured by the Wright spirometer ( V(sp)) were compared. The results were as follows: 1) Mean tidal volume was 248+/-92 ml, mean exhaled volume was 233+/-102 ml and mean spirometer volume was 19+/-97 ml. Thus the set and the measured tidal volume were different significantly (p<0.05). but we may calculate the actual tidal volume by the relationship with the set tidal volume ( Vsp-1.03V(T) - 56 ) 2) Mean compression factor was 1.35+/-0.92 ml/cmH2O.