Volume 54 · Issue 01 · 2018

At the beginning of 2018, Editor-in-Chief Wang Ningli wrote the foreword "Protecting Healthy Eyes and Lighting a Beautiful China" in this issue, pointing out that China's ophthalmology challenges and opportunities coexist, and difficulties and hopes coexist. We should expand the intersection of medicine and industry and the combination of medicine and enterprise research, attach importance to high-quality clinical research and basic research based on clinical needs, do a good job in the top-level design of ophthalmology talents, cultivate outstanding talents in grades and layers, and then comprehensively improve China's eye health level. With the national strategy of "Healthy China" as the goal, we should strive to achieve eye health for all.

At the National Health and Wellness Conference held recently, * put forward the concept of "Healthy China". He believed that "people's health should be placed in a strategic position of priority development", and to achieve a moderately prosperous society for the whole people, it is necessary to achieve health for the whole people. Eye health is an important part of universal health. The World Health Organization also mentioned in "Vision 2020" that by 2020, the goal of eye health accessible to everyone in the world should be achieved. Protecting healthy eyes is an important task to achieve the strategic goals of General Secretary's "Two Centenaries" and "Healthy China".

Corneal refractive surgery, as one of the common visual correction methods, has been increasingly accepted in China. There are a large number of people in China who undergo the corneal refractive surgery due to the high incidence of myopia in the country. It is essential that the safest and most effective surgery should be used to correct refractive errors in the cases involved with relatively normal eyes and corneas. In recent years, corneal refractive surgery has been rapidly developing with new technologies and techniques emerging all the time, such as SMILE (small incision lenticule extraction) surgery, which has been extensively applied in China since five years ago when it was approved by FDA. However, little known are these new technologies and techniques, and the clinical and basic researches need further investigations by various approaches including histopathology and molecular biology, combined with mathematics, computer science, physics, chemistry and corneal biomechanics. To achieve minimal tissue damage and optimal clinical outcomes on visual quality by corneal refractive surgery requires the multidisciplinary partnerships of medical practitioners and researchers. (Chin J Ophthalmol, 2018, 54: 3-6)

With the development of excimer laser and femtosecond laser equipment, application of diversified and customized surgical decision in modern corneal refractive surgery has been an inevitable trend. However, how to make a personalized decision with an accurate surgical design to achieve better visual quality becomes the main focus in clinical applications. Small-incision lenticule extraction (SMILE) and femtosecond assisted laser in situ keratomileusis (FS-LASIK) have been commonly acknowledged as the mainstream of corneal refractive surgery for ametropia correction nowadays. Both methods have been verified by clinical practice for many years. This article compares and elaborates the different characteristics with advantages and disadvantages of the two methods so as to provide some reasonable treatment options for refractive surgery. (Chin J Ophthalmol, 2018, 54: 7-10)

Preamble

In "Expert Consensus on Clinical Diagnosis and Treatment of Laser Corneal Refractive Surgery (2015)"^[1]On the basis of, the Optometry Group of Ophthalmology Branch of Chinese Medical Association reached this consensus through collective discussion on the specific personalized laser ablation technology guided by corneal topography.

To evaluate the changes of corneal transparency over the 1-year period after small incision lenticule extraction (SMILE) according to corneal Scheimpflug densitometry.

Prospective cohort study. Fifty-five patients (100 eyes) with myopia (19 male and 36 female, aged 18 to 39 years with average of 24) who underwent SMILE and regular follow-up for at least 1 year at Tianjin Eye Hospital were enrolled. Examinations took place before SMILE and postoperatively at 1 day, 1 week, and 1, 3, 6, and 12 months. The preoperative spherical equivalent of surgical refractive correction was (-5.75±1.64) D. Corneal densitometry (CD) data were calculated automatically by the Pentacam Scheimpflug system and expressed in gray scale units (GSU), from 0 (completely transparent) to 100 (completely opaque). During the analysis of corneal densitometry, the average corneal optical density of three concentric radial zones centered on the apex of the cornea ≤2 mm, >2 mm and ≤6 mm, >6 mm and ≤10 mm diameter) were applied, and three layers were defined according to different corneal depths (the anterior 120 μm as 1st layer, and the posterior 60 μm as 3rd layer, and the center part between them of the cornea as 2nd layer). The automatic release mode was applied in order to avoid operator-induced errors. The preoperative and postoperative values in different corneal layers and different concentric radial zones were compared using Kruskal-Wallis.

Ninty-three eyes(93%) of all eyes achieved uncorrected distance visual acuity (UCVA) of 0.8 or better on the first day postoperatively, and 96% (96 of 100 eyes) achieved UCVA of 0.8 or better in the first week postoperatevely, and all eyes 100% (100 of 100 eyes) achieved UCVA 0.8 or better until the end of our follow-up (in 1 year postoperatively). In general, the difference preoperative and postoperative corneal average optical density is of no statistical significance (χ²=8.446, P=0.207), specifically, the overall postoperative CD increased in the first week after surgery (1 day to 15.90, 1 week to 15.65), and then decreased to the equivalent of baseline levels and maintained such level until 6 months after surgery (1 month to 15.60; 3 month to 15.50, 6 month to 15.55), though at the 12-month follow-up, densitometry values had spiked significantly again (12 month, 15.90). The difference between the preoperative and postoperative CD values in the central two zones (≤2 mm, >2 mm and ≤6 mm), but not the outer (>6 mm and ≤10 mm), were of statistical significance (χ ²=61.961, 52.397, P<0.000). When subdivided by corneal layer, significant changes in CD were detected in the anterior 120 μm layer (χ ²=27.774, P<0.000). The CD increased significantly (i.e., corneal transparency decreased) as compared to the preoperative baseline on the first postoperative day, and lasted through the first week. There were no significant changes in the CD of the central layer (χ²=0.918, P=0.986). Significant increases in the posterior 60 μm of the cornea after surgery were found only at the 6-month and 1-year follow-up examinations (χ ²=17.469, P=0.008). No correlation was found in the preoperative refractive error, ablation depth, postoperative UCVA and the CD. The CD at 6 months was found negatively correlated with SE at 6 months (r=-0.219, P=0.028).

SMILE reduced corneal transparency temporarily and primarily within the surgically altered area, however such change has no significant correlation with the ablation depth, SE, and the postoperative UCVA. Transparency recovered within a month, but patients should be monitored for at least 1 year. (Chin J Ophthalmol, 2018, 54: 27-32)

To evaluate the role of Sirius combined topography and tomography system in screening for suspect keratoconus among the corneal refractive surgery candidates.

Retrospective case series study. Eight hundred and sixteen consecutive ametropic patients (1 632 eyes) who underwent routine examinations before corneal refractive surgery at Peking University Third Hospital from January 2016 to September 2016 were reviewed. All the cases were analyzed with Sirius combined topography and tomography system. Fifty-nine eyes of 37 patients, aged (28.9±7.4) years, classified as suspect keratoconus by the system were enrolled in the suspect group, including 25 females (40 eyes) and 12 males (19 eyes). A random eye of the first 59 patients, aged (27.1±6.4)years, whose both eyes were classified as normal by Sirius system were enrolled in the control group, including 38 females and 21 males. The corneal anterior surface, posterior surface and minimum thickness data of the suspect group were analyzed and then compared with the control group. The classified results were further verified by Pentacam system. Independent-samples t test and Mann-Whitney U test were applied to analyze the normal distribution and non-normal distribution data respectively.

The medians of anterior surface and posterior surface symmetry index and Baiocchi Calossi Versaci index of anterior surface and posterior surface of the suspect group were 0.84, 0.22, 0.58 and 0.51 D, and that of the control group were 0.05, 0.04, 0.09 and 0.06 D, and the differences were of statistical significance (Z=-18.764, -8.351, -12.248, -10.709, P<0.01). Mean corneal minimum thickness data of the suspect group were (504.4±30.0)μm, and that of the control group were (541.2±32.1)μm, the differences were of statistical significance (t=-6.408, P<0.01). In the suspect group, the eyes related with suspect or abnormal corneal anterior indices accounted for 47.5% (28/59), the eyes related with suspect or abnormal corneal posterior indices accounted for 55.9% (33/59), and the eyes related with suspect or abnormal corneal minimum thickness accounted for 40.7% (24/59). In the suspect group, 45 eyes (76.3%) were classified as suspect or abnormal according to the overall variance index "D" by Belin-Ambrósio Display (BAD) of the Pentacam system, and the other 14 eyes exhibited at least one abnormal index related with keratoconus.

Sirius 3D combined topography and tomography and its integral automatic classification system is capable to screen out the suspect keratoconus simply and effectively. These indices maybe arranged in descending order in terms of the sensitivity as corneal posterior surface, followed by corneal anterior surface and then corneal thinnest point thickness. (Chin J Ophthalmol, 2018, 54: 33-38)

To explore the change of optical zone after femtosecond laser assisted laser in sitn keratomileusis(FS-LASIK) so as to provide the reference for measurement and design of clinical optical zone.

This retrospective case series study covers 41 eyes of 24 patients (7 males and 17 females, aged from 18 to 42 years old) with myopia and myopic astigmatism who have received FS-LASIK surgery at Corneal Refractive Department of Qingdao Eye Hospital and completed over 6 months of clinical follow-up. Pentacam system (with the application of 6 corneal topographic map modes including: the pure axial curvature topographic map, the pure tangential curvature topographic map, the axial curvature difference topographic map, the tangential curvature difference topographic map, the postoperative front elevation map and the corneal thickness difference topographic map), combined with transparent concentric software (a system independently developed by Qingdao Eye Hospital) was used to measure the optical zone at 1, 3 and 6 months postoperatively, the optical zone diameters measurement results among different follow-up times in group were analyzed with the repeated measures analysis of variance, and the actual measured values and the theoretical design values of the optical zone were analyzed with independent-samples t-testing. Spearman correlation coefficient (r_s) have been applied to evaluate the relationship between postoperative optical zone measurement values and the potential influencing factors.

The optical zone diameters measured by pure axial curvature topographic map at 1, 3 and 6 months after FS-LASIK showed (6.55±0.50)mm, (6.50±0.53)mm and (6.48±0.53)mm respectively. The differences between values are of no statistical significance (F=1.60, P=0.21), the optical zone diameter measured by pure tangential curvature topographic map at 1, 3 and 6 months after FS-LASIK showed (5.44±0.46)mm, (5.46±0.52)mm and (5.44±0.50)mm respectively, the differences between values are of no statistical significance (F=0.17, P=0.85). The optical zone diameters measured by postoperative front elevation map at 1, 3 and 6 months after FS-LASIK showed (5.06±0.28)mm, (5.12±0.32)mm and (5.17±0.28)mm respectively. The differences between the values of 3 and 6 months postoperatively are of no statistical significance (F=6.14, P=0.15), the optical zone diameters measured by axial curvature difference topographic map at 1, 3 and 6 months after FS-LASIK showed (6.51±0.37)mm, (6.45±0.41)mm and (6.41±0.40)mm respectively, and the differences between the values of 3 and 6 months postoperatively are of no statistical significance (F=7.25, P=0.05). The optical zone diameters measured by tangential curvature difference topographic map at 1, 3 and 6 months after FS-LASIK showed (5.21±0.23)mm, (5.16±0.19)mm and (5.17±0.20) mm respectively, and the differences between the values of 1 and 3 months postoperatively are of statistical significance (F=1.75, P=0.04). The optical zone diameters measured by corneal thickness difference topographic map at 1, 3 and 6 months after FS-LASIK showed (6.53±0.40)mm, (6.39±0.43)mm and (6.41±0.47)mm respectively, and the differences between the values of 1 and 3 months postoperatively are of statistical significance (F=1.67, P=0.032). The actual measured optical zone values from the 6 different modes of Pentacam system are less than the theoretical design values (7.75 mm), and the differences were statistical significance (t=-15.42, -29.39, -59.27, -21.47, -81.69, -18.22, P<0.01).

The optical zone measurement values tend to be stable at 3 months after FS-LASIK. The actual measured values from all the 6 different modes of Pentacam system were less than the theoretical design values. The results from pure tangential curvature topographic map, the tangential curvature difference topographic map and the postoperative front elevation map showed greater variation with clear border, which was beneficial for eccentric research. The results from pure axial curvature topographic map, the axial curvature difference topographic map and the corneal thickness difference topographic map were close to the theoretically designed values. Furthermore, the axial curvature difference topographic map showed clearer border and less variation thus maybe more favorable for measuring optical zone in clinical application.(Chin J Ophthalmol, 2018, 54: 39-47)

To observe the change of refractive status and possible influencing factors for patients with different corneal power who underwent small incision lenticule extraction (SMILE) surgery.

Prospective cohort study was performed for patients who underwent small incision lenticule extraction (SMILE) surgery at Daping Hospital and Research Institute of Surgery of Third Military Medical University between January and August 2016. The patients were divided into 3 groups according to their corneal power: low curvature group (K₁≤41.00 D), common curvature group (41.00 D<K₁ and K₂< 46.00 D), and high curvature group (K₂ ≥ 46.00 D). Preoperative and postoperative (1 day, 1 week, 1, 3 and 6 month) ophthalmic examination results of the patients including uncorrected distance visual acuity (UCDVA), refractive status, intraocular pressure (IOP) and slip lamp microscope examination were recorded. Subjective refraction and Pentacam HR were detected at 6 month after operation so as to monitor the incidence of intraoperative and postoperative complications. The total corneal refractive power (TCRP) based on Ray Tracing technique was applied to evaluate the changes of corneal curvature before and after the surgery. Power vector analysis was applied to evaluate the refraction status based on preoperative and postoperative corneal topography. At 6 months postoperatively, Hotelling t² test was applied to compare the refractive status among the groups, and multiple linear regression was applied to analyze the potential influencing factors of under-correction/over-correction.

Fifty-four patients (108 eyes) were enrolled, among which 34 were male (68 eyes) and 20 were female (40 eyes). The 3 groups had the same sample size (18 patients and 36 eyes). The low curvature group was featured with youngest average age [(22±4) years, χ ²=8.94, P<0.05], largest male patients proportion (15/18, χ ²=11.20, P<0.01) and largest average pupil diameter [(3.26±0.36) mm, F=4.83, P<0.05], as compared to the other 2 groups. The incidence of severe OBL (25/36) was significantly higher in the high curvature group (χ²=65.06, P<0.01). All patients showed no diminution of vision and their UCDVA averaged 5.1 at 6 months postoperatively, however patients with low curvature were slightly "under-corrected" in 1-mm and 2-mm zones (Error values<0). The preoperative spherical equivalent (SE) and postoperative spherical aberration in 6-mm zone were the significant factors affecting the relationship between preoperative corneal curvature and postoperative refractive status (r=0.392, 2.745, P<0.05).

SMILE is safe and effective for patients with both low and high curvature, but the incidence of intraoperative OBL is significantly higher in high curvature group. Patients with low curvature were slightly "under-corrected" in 1-mm and 2-mm zones, which may imply that the design of the lenticule may be aspheric and that the cornea reshaping process of younger patients may be of particular characteristics. (Chin J Ophthalmol, 2018, 54: 48-54)

To evaluate the accommodative response of patients with intermittent exotropia (IXT) objectively, and study the changes of accommodative response of intermittent exotropia patients when maintaining binocular fusion.

The prospective cohort study was used in this study. Twenty-four patients diagnosed with basic intermittent exotropia who visited the eye hospital of Wenzhou Medical University during October 2016 through January 2017 together with 24 normal volunteers were included, the 48 participants aged from 10 to 27 years old. The participants were divided into the case group and the control group. There were 11 males and 13 females in the case group, and 7 males and 17 females in the control group. The Open-filed autorefractor WAM-5500 (Grand Seiko, Japan) was used to measure the accommodative response of each eye under binocular and monocular viewing conditions at 5 m and 40 cm respectively. During the measurement, patients wore full correction spectacles to achieve distant best-corrected visual acuity of both eyes. The accommodative responses of each eye under binocular and monocular viewing conditions at distance or near between fellow eyes and groups were compared.

Under near fixation (40cm) binocular viewing conditions, the accommodative response of the fixating eye (-1.915±0.301)D was different from the deviating eye -1.649(-2.020, -0.304)D in the case group (Z=-3.714, P<0.001). Under near fixation monocular viewing conditions, the accommodative response of the fixating eye (-1.653±0.271)D was also different from the deviating eye -1.565 (-2.031, -0.667)D in the case group (Z=-2.971, P=0.003). During binocular viewing, the asymmetric value of the accommodative response between both eyes of the case group was 0.389(0.102, 1.458)D which was more significant than the normal controls' 0.155(0.009, 0.573)D (Z=-3.505, P<0.001), but during monocular viewing, there was no significant difference between the groups (Z=-1.908, P=0.056). Under near viewing conditions, the variation value of the fixating eyes of the case group was -0.228(-0.796, 0.382)D, which was greater than the variation value -0.086(-0.606, 0.628)D of the right eye of the normal controls, such difference is of statistical significance (Z=-2.279, P=0.023). Under distance viewing conditions, there was no significant difference in the accommodative response between fixating eyes and deviating eyes in case group neither during monocular viewing nor binocular viewing (t=-1.525, -1.729, P>0.05). Besides, the asymmetric values of accommodative response between groups were not significantly different (Z=-1.433, P=0.152. Z=-0.938, P=0.348). Under distance viewing conditions, the changes in accommodative response of each eye during both monocular viewing and binocular viewing were not significantly different between case group and normal controls (Z=-0.041, P=0.967. Z=-1.433, P=0.152).

The accommodative responses of the fixating eye and deviating eye of patients with intermittent exotropia were asymmetric under near fixation binocular viewing conditions, and the accommodative response of the deviating eye tends to decrease. Besides, the change of accommodative response of the patients with intermittent exotropia when maintaining binocular fusion is more significant than that of the normal controls. (Chin J Ophthalmol, 2018, 54: 55-61)

To discuss the dynamic changes and correlation of macular ganglion cell (mGCC) and peripapillary retinal nerve fiber layer (pRNFL) of neuritis patients through optical coherence tomography (OCT).

A retrospective case series study. Eleven eyes from 11 patients who have been diagnosed with neuritis and received regular follow-up during June 2013 through June 2015 were included. The dynamic characteristic changes of mGCC and pRNFL over the course of disease, as well as their correlations between best visual acuity and visual field have been analyzed based on OCT measurements.

According to the observation on the 11 eyes of the 11 patients, patients showed symptoms of decreased vision, abnormal visual field, swollen mGCC and pRNFL with normal or increased thickness during the subnormal period. During the advance-separation period (around 3 weeks), the thickness of mGCC decreased resulting from atrophy while pRNFL was still swollen. Druing the late period (usually 6-8 weeks after onset of the disease), both mGCC and pRNFL were getting thinner due to atrophy. Vision acuity and visual field of the patients improved after treatment, however, they were still not comparable with the normal level before the disease.

The thickness changes of mGCC and pRNFL differs in neuritis patients over time. OCT can help us in detecting these changes, thus provide a foundation for us to further explore the treatment and anatomical changes of neuritis patients. (Chin J Ophthalmol, 2018, 54: 62-68)

A 5-year-old female child went to Beijing Tongren Hospital affiliated to Capital Medical University for treatment because she was "found to tilt her head for 2 years". In the past 2 years, the parents of the patient found that the patient liked to tilt his head to see objects, without diplopia, dizziness, headache and obvious numbness and weakness of the limbs. Past history: The patient weighed 3 kg and was 50 cm long at birth, and had a term cesarean section. Physical examination: clear consciousness, slightly poor expression ability, lack of cooperation in physical examination. The vital signs are stable, the bilateral pupils are equal size and round, about 3 mm in diameter, and they are sensitive to light. The limbs moved normally, physiological reflexes existed, and the pathological signs were not drawn out. The naked eye visual acuity examination of both eyes did not cooperate, and the corrected visual acuity of the right eye was 0.7⁺0.7 in left eye^-。 Compensatory head position: head tilted towards right shoulder (Figure 1), there was no relief in head position after monocular covering. Eye position: The straight angle of the left eye gaze and the right eye gaze is equal by corneal photomapping, with the left high and the right 5°; Triangular prism method check: 10 high left and right when sitting^△When fixing horizontally and laterally, the strabismus degree of the second fixation eye position is both left and right 10^△。 Left high right 5 in recumbent position^△。 Bielschowsky cephalic skew test was negative. Eye movement: the right eye turns up and falls slightly, and the left eye turns down; The adduction and abduction movements of both eyes were basically normal. Isoscopic machine: Ⅰ: -2°, Ⅱ: none, Ⅲ: (-), no near stereoscopic vision; Objective angle: -5°, left high and right 2°. The fundus image suggests that the patient has external rotation of the right eye and internal rotation of the left eye (Figure 2）。 Preliminary diagnosis: Skew deviation. MRI of the brain was performed in our hospital, and it was found that the left cerebellar hemisphere and bridge arm were swollen, showing flaky isometric, long T1, mixed with slightly longer T2 signal shadows, with unclear edges, about 35.6 mm ×25.9 mm in size, and the enhanced scan showed mild and uneven enhancement; The left bridge arm was thickened, and the fourth ventricle was compressed and deformed; Consider the possibility of glioma (Figure 3）。

The patient was a 28-year-old female. Because of the poor vision of both eyes since childhood for more than 20 years, I went to Xiamen Eye Center. Eye examination: right eye visual acuity was 0.08 in the naked eye and 1.0 in the corrected eye (-6.00 DS); The left eye visual acuity was 0.05 in the naked eye and 0.6 in the corrected eye (-5.25 DS); IOP was 17.0 mmHg (1 mmHg =0.133 kPa) in the right eye and 18 mmHg in the left eye; The cornea of both eyes was transparent, there was no sediment behind the cornea, the depth of the anterior chamber was normal, the aqueous humor was clear, the pupil was round, the diameter was 3 mm, the direct and indirect reaction to light was present, and the lens was transparent; The vitreous body of both eyes was mildly opaque, the optic disc was reddish in color with clear borders, and the retinal and choroidal absence was visible near the macular area (Quintessence Picture 1，Quintessence Picture 2), deletion region edge pigmentation. Clinical diagnosis: congenital macular defect in both eyes.

3D printing is a kind of technology that makes 3D models from computer-aided designs through additive manufacturing, in which successive layers of the material are deposited onto underlying layers to construct 3D objects. In recent years, 3D printing is gradually applied in the field of ophthalmology, such as the cornea, retina, orbital operation, ocular tumor radiotherapy, ocular implants and ophthalmology teaching. This article reviews the application status of 3D printing technology in the basic research and clinical treatment in ophthalmology. (Chin J Ophthalmol, 2018, 54: 72-76)