ObjectiveTo explore the distribution of choroidal thickness and its influence factors in university students.MethodsA cross-sectional study. A total of 896 eyes of 896 college students were included in the study. Among them, there were 350 males (350 eyes) and 546 females (546 eyes). All the eyes were right eyes. The average age was 19.18 ± 1.36 years old. According to the spherical equivalent refraction (SER), the eyes were divided into non-myopia group, low myopia group, moderate myopia group and high myopia group, which were 59, 251, 356 and 230 eyes, respectively. The subfoveal ChT (SFCT) was measured using a swept-frequency source optical coherence tomography scanner. According to the ETDRS, the choroid within 6 mm of the fovea was divided into three concentric circles centered on the fovea of the macula, which were the central area with a diameter of 1 mm, the inner ring area of 1-3 mm and the outer ring area of 3-6 mm. The outer ring area of 3-6 mm has a total of 9 zones. The inner ring and outer ring 4 regions were superior, inferior, nasal and temporal, respectively. The distribution characteristics of ChT in different regions, genders and diopter groups were observed. Bivariate correlation analysis were used to analyze the correlation of ChT and SER, axial length (AL).ResultsThe average SFCT of 896 eyes was 221.28±67.35 μm. The mean SFCT of males and females were 227.20±69.38 and 217.50±65.80 μm, respectively. The difference of SFCT between different genders was statistically significant (t=2.075, P=0.038). Compared with the central region ChT, there was no significant difference in ChT between the outer ring and the outer region (t=0.086, P=0.932). The difference of ChT in other regions was statistically significant (t=-21.973, -5.818, 36.328, -3.065, -18.017, -10.595, 57.007; P＜0.001, ＜0.001, ＜0.001, ＜0.002, ＜0.001, ＜0.001, ＜0.001). In the horizontal direction, ChT gradually thickens from nasal to temporal (F=2 251.558, P＜0.001); in the vertical direction, ChT gradually decreases from superior to the central, but have a little increased from central to inner inferior, then decreased to outer inferior again (F=45.425, P＜0.05). Correlation analysis showed that SFCT was negatively correlated with AL (r=0.478, P＜0.01) and a negative correlation with axial length (r=?0.395, P＜0.01), and positively correlated with SER (r=0.478, P＜0.01). SFCT decreased by 12.29 μm for every in myopic refractive error of 1 D, or by 20.14 μm for every increase in AL of 1 mm.ConclusionsChT is changed by different location. The horizontal direction is gradually thickened from nasal to temporal. The vertical direction is thicker than the center. The inferior inner ring area is thicker than the outer ring area. Gender, SER and AL are the influencing factors of SFCT.
Objective To observe visual field outcome and refractive status of patients with retinopathy of prematurity (ROP) treated by laser photocoagulation. Method The data of 39 ROP patients (73 eyes) who received laser photocoagulation were retrospectively analyzed and compared with 13 normal control subjects (25 eyes) whose age and sex were matched with ROP group. There were 24 males (45 eyes) and 15 females (28 eyes) in ROP group, with an average age of (7.0±1.28) years. The first laser treatment was carried out at postnatal age (PA) of (38.74±3.82) weeks, the birth weight (BW) of (1402.33±369.61) g and the number of laser burns was (517.86±277.40). The control group included 7 females (13 eyes) and 6 males (12 eyes), with an average age of (7.17±0.96) years. The age (t=0.691) and gender (χ2=1.425) were comparable between the two groups (P=0.491, 0.233). The data of patients and controls were retrospectively analyzed including best corrected visual acuity, refractive examination, automated perimetry test. The differences of the mean deviation (MD) of visual field and the spherical equivalent (SE) between these two groups were comparatively observed. ROP patients were divided into no VF loss group (MD≤2 dB) and VF loss group (MD＞2 dB), mild VF loss group (MD≤6 dB) and moderate VF loss group (MD＞6 dB) according to the results of automated perimetry test, the differences of gestational age (GA), PA, BW, number of laser burns and SE between these groups were comparatively observed. Results The MD in ROP group and control group were 4.87±5.12 dB and 1.27±3.34 dB, respectively; the difference between the two groups was statistically significant (t=–4.01,P＜0.001). The subgroup analysis showed that BW, number of laser burns, and SE were significantly different between no VF loss group and VF loss group (t=2.074, –1.996, –2.162;P=0.042, 0.026, 0.034); while the GA was not significantly different between these two groups (t=1.973,P=0.052). The difference of PA was not statistical significant different between mild VF loss group and moderate VF loss group (t=2.03,P=0.051) and SE was significantly different between the above two groups (t=3.283,P=0.002). For refractive outcomes, the BW and ROP stage correlated with SE significantly (r=–0.304, –0.387;P=0.015, 0.002). The mean BCVA in ROP group was 0.84±0.23, and 59 eyes (91.2%) with BCVA better than 0.5. Conclusion Laser treatment for ROP tends to have less effect on long term refractive status and VF loss, with good visual outcome.
In order to understand how the biomechanical properties of rabbit cornea change over time after corneal ablation, 21 healthy adult rabbits were used in this study, with the left eye as experimental side and the right eye as the control side. Firstly, a lamellar knife was used to remove a portion of the anterior corneal surface tissue (30%~50% of the original corneal thickness) from the left eye of each rabbit, as an animal model simulating corneal refractive surgery. Secondly, postoperative experimental rabbits were kept for one, three, or six months until being euthanized. Strip specimens were produced using their corneas in vitro to perform a uniaxial tensile test with an average loading-unloading rate of approximately 0.16 mm/s. Finally, the visco-hyperelastic material constitutive model was used to fit the data. The results showed that there was a significant difference in the viscoelastic parameters of the corneas between the experimental and the control eyes at the first and third postoperative months. There was a difference in tangential modulus between the experimental and the control eyes at strain levels of 0.02 and 0.05 at the third postoperative month. There was no significant difference in biomechanical parameters between the experimental and the control eyes at the sixth postoperative month. These results indicate that compared with the control eyes, the biomechanical properties of the experimental eyes vary over postoperative time. At the third postoperative month, the ratio of corneal tangential modulus between the experimental and the control eyes significantly increased, and then decreased. This work lays a preliminary foundation for understanding the biomechanical properties of the cornea after corneal refractive surgery based on rapid testing data obtained clinically.
Objective To investigate the refractive shift after combined surgery （phacoemulsification, intraocular lens implantation and vitrectomy） by comparing the difference between the predictive and postoperative refractive power.Methods The clinical data of 44 patients (48 eyes) underwent combined surgery (combined group) and 30 patients (50 eyes) underwent cataract surgery (cataract group) were retrospective analyzed. Combined group was further divided into two sub-groups by the kind of tamponade: balanced salt solution group and gas group. Before surgery, axial length and corneal curvature were measured, and the predictive spherical equivalent (PSE) was calculated. Axial length, corneal curvature and actual spherical equivalent (ASE) were measured in six months after surgery. The differences between PSE and ASE were compared between combined group and cataract group, balanced salt solution group and gas group.Results In combined group,the mean PSE was (-0.10plusmn;0.42) D and ASE was（-1.00plusmn;1.10） D, and the difference was significant（t=6.687, P＜0.05）. Patients underwent combined surgery showed a statistically significant myopic shift compared with those underwent simple cataract surgery （t=-3.792,P＜0.05）, the refractive shift of balanced salt solution group and gas group were (-0.76plusmn;0.89） and （-1.19plusmn;0.94） D respectively, and there was no significant difference（t=-1.530,P＞0.05）.Conclusion Combined surgery of phacoemulsification and vitrectomy tends to shift the actual refractive status to myopia.
Objective
To verify the changes of optics and refraction of the eyes after retinal detachment surgery with the tamponade of silicone oil in vitreous cavity.
Methods
The optical calculation was taken as the following by using the parameter of Gullstrand model eye:（1）The refraction of silicone filled eye in non-accommodative status;（2）The refraction of silicone filled eye in non-accommodative status;（3）The aniseikonia analysis when one eye filled with the silicone oil;（4）The IOL power re-calculation．
Results
（1） Compa red with the normal eye,the eye filled with silicone oil is moved toward high hyperopia of +9．19 D;（2）When corrected,the accommodation amplitude reduced 1.42 D induced by filling silicone oil.
Conclusion
When eye filled with silicone oil,the change of refractive power tends to be highly hyperopic,the amplitude of accommodation decreased,and the regular IOL power calculation formula is no longer available.
(Chin J Ocul Fundus Dis，2000，16：139-212)
ObjectiveTo investigate the potential effect of hyperopia status on subfoveal choroidal thickness (SFCT) in silicone oil (SO)-filled eyes.MethodsThis self-comparative study was conducted in Department of Ophthalmology, Central Theater Command General Hospital. The 50 patients (100 eyes) were collected with unilateral macula-on rhegmatogenous retinal detachment from January 2019 to July 2019, who successfully underwent pars plana vitrectomy (PPV) and SO tamponade. Retinal reattachment was observed after surgery in all patients. One month after PPV, the affected eye was wore soft, contact lenses for 24 hours to correct refractive error (RE), depending on its optometry value. The SFCT of the affected eyes was measured using OCT before and after lenses wear. The fellow eyes also received OCT examination at the same time. T test was used to compare SFCT between SO-filled eyes and fellow eyes.ResultsThe mean RE of the SO-filled eyes was +6.38±1.12 D. The mean SFCT of SO-filled eyes (247.12±17.63 μm) was significantly thinner than that of the fellow eyes (276.32.55±17.63 μm) (P＜0.001). The SFCT of the SO-filled eyes was significantly thinner than fellow eyes, and the difference was statistically significant (t=－3.95, P＜0.001). After lenses wear, the mean SFCT of the SO-filled eyes increased to 276.32±24.86 μm. Compared with before lenses wear, the difference was statistically significant (t=－4.30, P＜0.001). Compared with the fellow eye, the difference was not statistically significant (t=0.05, P＞0.05).ConclusionSFCT reduction in the SO-filled eyes may be due to the hyperopia status caused by SO, which can be reserved by RE correction.
