Optical Coherence Tomography OfA Nterior Segment Accommodative Changes With Posterior Chamber Phakic Intraocular Lens In High Myopia

Aims:To investigate changes of the anterior segment biometry during accommodation with posterior chamber phakic intraocular lens in high myopia using UL OCT.Methods:12 eyes of 12 patients undergoing implantable collamer lens(ICL)at the First Affiliated Hospital of Zhejiang University during January 2016 to May 2016 were enrolled.The follow-up period was between six months and one year.Pupil diameter(PD),comeal endothelium to lens distance(Endo-L),corneal endothelium to ICL distance(Endo-ICL),ICL to lens distance(ICL-L),ICL thickness(ICL T)and angle opening distance at500pm(AOD 500),angle opening distance at750pm(AOD 750),trabecular-iris space area at500μm(TISA 500),trabecular-iris space area at750μm(TISA 750),anterior chamber angle(ACA)at temporal and nasal anterior chamber were measured at states of relax and 2D,4D,6D,8D accommodative stimulation using UL OCT.All statistical analyses were evaluated using SPSS software v.20.After determining that data for each variable were normally distributed,then the data were expressed as mean ± standard deviations.A repeated measure analysis of variance(rANOVA)was performed to study if there were significant differences among vergence conditions for each of the anterior segment biometry.The LSD was used for comparisons between data groups when rANOVA showed significant differences between measurements.A p-value less than 0.05 was considered statistically significant.Results:The mean PD at the relax state and 2D,4D,6D,8D accommodative state were 5.896±1.048mm,5.627±1.169mm,5.473 ± 1.123mm,5.346 ± 1.098mm,4.670±0.794mm;The mean Endo-L at the relax state and 2D,4D,6D,8D accommodative state were 3.010±0.183mm,2.971 ± 0.195mm,2.934 ± 0.201mm,2.851±0.166mm,2.775 ±0.176mm;The mean Endo-ICL at the relax state and2D,4D,6D,8D accommodative state were 2.250±0.171mm,2.194±0.196mm,2.141±0.194mm,2.024±0.160mm,1.885±0.163mm;The mean ICL-L at the relax state and2D,4D,6D,8D accommodative state were 0.516±0.064mm,0.533 ± 0.064mm,0.550 ± 0.066mm,0.585±0.062mm,0.647 ±0.097mm.There were significant differences among the different accommodative states for PD,Endo-L,Endo-ICL,ICL-L and AOD500,AOD750,TISA500,TISA750,ACA at temporal and nasal anterior chamber after the rANOVA(P<0.05).The LSD showed that significant differences in the Endo-ICL,ICL-L,Endo-L among the five accommodative stimulus(P<0.05).A significant increase in ICL-L was accompanied by a significant reduction in Endo-ICL and Endo-L(P<0.05).Significant differences were found in PD and AOD500,AOD750,TISASOO,TISA750,ACA at temporal anterior chamber and ACA,AOD750,TISA750 at nasal anterior chamber between the relax state and 2D,4D,6D,8D accommodative state(P<0.05).And there were significant differences among the relax state and 4D,6D,8D accommodative state in AOD500 and TISA500 at nasal anterior chamber,except 2D accommodative state.Not all Significant differences were found between any two data groups in PD and measurements of anterior chamber.But the overall trend decreased.Conclusion:During accommodation,PD,Endo-L decreased significantly.Besides,there were a significant increase in ICL-L accompanied by a significant reduction in Endo-ICL due to the anterior movement of ICL.The anterior chamber angle had a tendency to be smaller during accommodation.