Volume 53 · Issue 07 · 2017

This issue focuses on the research progress of ophthalmic epidemiological investigation. Professor Zou Haidong is the responsible editorial committee responsible for the planning, composition and review of the key contents of this issue.

The core goal of "Thirteenth Five-Year Plan for National Eye Health (2016 to 2020)" is to obtain eye health. At present, there are still several problems hampering Chinese eye health management system development, including the lack of top policy design, system protection and financial investment, weak support from primary health care institutions, other medical disciplines and social forces, and insufficient digital information. To achieve effective eye health management, it is necessary to address the sustainability of eye health management, the integrity of eye health digital information data and the feasibility of eye health payment. It is recommended that eye health-related medical workers take positive actions to strengthen the digital information construction and service capacity construction of eye disease prevention and control network, carry out health promotion extensively, and conduct eye health management mode research and practice.(Chin J Ophthalmol, 2017, 53: 481-483)

Eye health is an important part of national health. Visual impairment, including blindness, seriously affects people's physical health and quality of life, increases the burden of families and society, threatens social and economic production activities, and is a major public health and social problem involving people's livelihood. In 1999, the World Health Organization (WHO) and the International Association for the Prevention of Blindness (IAPB) put forward the global strategic goal of "eliminating avoidable blindness by 2020". In accordance with the overall requirements of building a healthy China, deepening the reform of the medical and health system and the resolution of WHO's "Facing Universal Eye Health: 2014-2019 Global Action Plan", this plan is formulated in order to continue to promote the cause of eye health in China during the 13th Five-Year Plan period and further improve the people's eye health level.

The average altitude of Qinghai-Tibet Plateau in China is over 4 000 m, the intensity of ultraviolet irradiation is extremely strong, the oxygen content in the air is low, the natural environment factors and the backward medical conditions make the incidence of cataract in Tibet Autonomous Region about 60% higher than that in other areas of China^[1]It has become one of the regions with high prevalence and blindness rate of cataract in China. Facing the current situation of cataract incidence in Tibet Autonomous Region, as a grass-roots medical worker in Tibet Autonomous Region, I have a deeper understanding of the problem and the focus of clinical work, and put forward relevant coping strategies, hoping to get everyone's attention.

To investigate the prevalence, subtypes and risk factors of cataract in type 2 diabetic individuals.

Geographically defined cluster sampling method was used in this population-based, cross-sectional study. There were 7 756 type 2 diabetes individuals in Xinjing Town with a residential population of 88 864. The type 2 diabetic individuals were randomly selected from 20 basic sample units in Xinjing Town of Changning District from April to June 2016. All participants received visual acuity measurement and eye examination. The standard of lens opacity assessment was according to the Lens Opacities Classification SystemⅡ(LOCSⅡ). The prevalence of cataract in diabetic individuals was calculated with LOCS≥2. Multivariate Logistic regression analysis was used to explore the relevant factors of cataract in type 2 diabetic individuals.

A total of 1 719 type 2 diabetic individuals were included in the analysis. There were 682 men (39.67%) and 1 037 women (60.33%) in this population. There were 434 cataract individuals and the prevalence of cataract was 25.25%. There were 269 cases of nuclear type (15.7%), 38 cases of cortical type (2.2%), 2 cases of posterior subcapsular type (0.12%) and 42 cases of mixed type (2.4%) in the 1 719 individuals. Multivariate Logistic regression analysis showed that age (P<0.001), duration of diabetes (P<0.001), education (P=0.005), fasting blood glucose (P_{6.1-7.7mmol/L}=0.025, P_{7.8-24.3mmol/L}=0.022, compared with 3.6-6.0 mmol/L of fasting blood glucose), and ocular axial length (P<0.001) were associated with cataract.

Cataract is a common ophthalmic disease in adults with type 2 diabetes in Xinjing Town. Regular screening of diabetes in the high risk population and intensive control of both glucose and blood pressure in diabetic patients are recommended to prevent and delay the development of cataract. (Chin J Ophthalmol, 2017, 53: 489-494)

To investigate the distribution of tear film lipid layer thickness (LLT) and the relationship between symptoms and signs of dry eye and tear film LLT in the population of Taishitun Community in Beijing.

A cross-sectional study. From May 2016 to August 2016, three streets of Taishitun Community were randomly selected as survey districts and 540 persons were taken as investigation subjects. Every participant completed 6 items of dry eye examinations as follows: questionnaire (Ocular Surface Disease Index, OSDI), measurement of tear film LLT, tear film break-up time (TBUT), corneal and conjunctival staining, SchirmerⅠtest and the infrared meibomian photography. According to their age, all participants were divided into four groups: junior group (<18 years old), youth group (18 to 40 years old), middle-aged group (41 to 59 years old) and the elderly group (over 60 years old). With the OSDI criteria, no dry eye symptom group (score, <12 points), mild to moderate dry eye symptom group (score, 12 to 32) and severe dry eye symptom group (score, 33—100) were included. With the statistical methods of variance analysis and multivariate Logistic regression analysis, distribution of the variables of LLT and the relationship between dry eye symptoms and LLT were studied.

A total of 473 residents finally participated in this study, and the response ratio was 87.6%. The values of LLT were normally distributed. The average LLT was (59.87±18.50) nm [(60.16±19.15) nm in males and (59.67±18.57) nm in females], and the comparison of LLT with different genders was not statistically significant (t=0.198, P=0.843). The tear film LLT of four different age groups had statistical significance (F=15.092, P<0.05), and increased with age [(56.10±18.33) nm in the junior group, (54.60±16.29) nm in the youth group, (60.61±19.18) nm in the middle-aged group and (73.25±14.58) nm in the elderly group]. The LLT was inversely proportional to the severity of dry eye symptoms. With a thinner LLT, the symptoms of the subjects turned severe. In the elderly with different degrees of symptoms, the LLT was significantly different (F=0.019, P<0.05), while in the youth and middle-aged groups with different degrees of symptoms, the LLT was not significantly different (F=0.096, P>0.05.F=0.538, P>0.05). In the OSDI symptom questionnaire, only blurred vision and decreased visual acuity were related to the tear film LLT (P<0.05). There was no significant correlation between the TBUT, SchirmerⅠtest result, meibomian gland loss rate and the tear film LLT (P>0.05).

In Taishitun Community of Beijing, the values of tear film LLT had a normal distribution. The LLT was positively correlated with age, but inversely correlated with the severity of the symptoms of dry eye. There was no significant correlation between the LLT and the TBUT, SchirmerⅠtest result and meibomian gland loss rate.(Chin J Ophthalmol, 2017, 53: 495-501)

To investigate the prevalence of visual impairment and factors associated with visual impairment among people aged 50 years and above in Funing County, Jiangsu Province.

Cross-sectional study. Random cluster sampling was used in selecting individuals aged ≥50 years in 30 clusters, and 5 947 individuals received visual acuity testing and eye examination. Stata 13.0 software was used to analyze the data. Multivariate logistic regression was used to detect possible factors of visual impairment such as age, gender and education. Statistical significance was defined as P< 0.05.

A total of 6 145 persons aged 50 years and above were enumerated, and 5 947 (96.8%) participants were examined. Based on the criteria of World Health Organization (WHO) visual impairment classification and presenting visual acuity, 138 persons were diagnosed as blindness, and 1 405 persons were diagnosed as low vision. The prevalence of blindness and low vision was 2.32% and 23.63%, respectively. And the prevalence of visual impairment was 25.95%. Based on the criteria of WHO visual impairment classification and best-corrected visual acuity, 92 persons were diagnosed as blindness, and 383 persons were diagnosed as low vision. The prevalence of blindness and low vision was 1.55% and 6.44%, respectively. And the prevalence of visual impairment was 7.99%. Concerning presenting visual acuity and best-corrected visual acuity, the prevalence of blindness and low vision was higher in old people, females and less educated persons. Cataract (46.63%) was the leading cause of blindness. Uncorrected refractive error (36.51%) was also a main cause of visual impairment.

The prevalence of visual impairment is higher in old people, females and less educated persons in Funing County, Jiangsu Province. Cataract is still the leading cause of visual impairment. (Chin J Ophthalmol, 2017, 53: 502-508)

To determine the prevalence of diabetic retinopathy (DR) and diabetic peripheral neuropathy (DPN) in the Beijing Desheng Diabetic Eye Disease Study cohort and to investigate the association between DR and DPN.

Cross-sectional study in a type 2 diabetic cohort. Questionnaires were collected and physical examinations were performed. Ophthalmologic examinations consisted of visual acuity with pinhole, slit-lamp examination of the anterior segment and seven-field 30^o mydriatic fundus photography. The severity of DR was graded using a modified ETDRS method. Peripheral neuropathy examinations included 10-g Semmes-Weinstein monofilament, 128-Hz tuning fork and Tip-Therm. Statistical analysis was performed using SPSS software version 19.0.

A total of 959 patients with type 2 diabetes mellitus were enrolled, among whom 354 (36.9%) had DR and 523 (54.5%) had DPN. The prevalence of DPN was 61.8% in patients with DR and 50% in patients with no DR (χ²=13.66, P<0.01). Logistic regression analysis showed that DR was associated significantly with age (OR=1.03, 95%CI: 1.01-1.06) and gender (male) (OR=2.32, 95%CI: 1.51-3.58), whereas the presence of DPN increased the risk of DR (OR=1.5, 95%CI: 1.12-2.01).

DPN is commonly seen in patients with type 2 diabetes mellitus and increases the risk of DR. (Chin J Ophthalmol, 2017, 53: 509-513)

To assess the prevalence, surgical coverage rate and social burden rate of cataract blindness among adults aged ≥60 years in the suburban population of Nantong, Jiangsu, China.

It was a population-based cross-section study. A census with individuals aged ≥60 years was conducted in two villages of the suburb area in Nantong from June to August, 2008. A total of 1 305 individuals received visual acuity and eye examinations. Lens and cataract operative status were evaluated by slit-lamp biomicroscopy. Multiple logistic regression analysis was employed to analyze the prevalence of cataract, cataract surgical coverage rate and cataract blindness social burden rate among different ages, genders, educational backgrounds, marital statuses and salary levels. The results in the suburb were compared to the urban and rural areas.

Among 1 305 individuals, 376 cases of cataract were found. The prevalence of cataract was 28.81%. The rate was higher in the aged, less educated and low salary persons (P<0.01). In 47 eyes with cataract surgery, 19.15% of eyes were treated by modern extra-capsular surgery and 38.30% received phacoemulsification. The rate of intraocular lens implantation was 57.45%. The cataract surgical coverage rate was 40.48% and the cataract blindness social burden rate was 3.22%. The cataract surgical coverage rate was higher in the primary-educational persons than illiterate persons (P<0.05). The cataract blindness social burden rate was higher in ≥80-year-old persons than ≥60-year-old persons (P<0.05) and lower in married persons than single persons (P<0.05). The cataract surgical coverage rate was lower in the suburb area than in the city area, while the cataract blindness social burden rate was opposite. The rate of postoperative presenting visual acuity and best-corrected visual acuity of over 0.7 was 14.89% and 23.40% in the operated eyes, respectively. The main causes of unfavorable postoperative visual acuity (<0.3) were retinal disorders, post-capsular opacity, corneal opacity, refractive errors and glaucoma.

Cataract is the most common and important eye disease that may lead to blindness and severe visual impairment among adults aged 60 years or above in the suburb of Nantong City. The prevalence of cataract is related to age, education background and economy level. The cataract surgical coverage rate is low and the cataract blindness social burden rate is high. The first important task in blindness prevention is still the elimination of cataract blindness and the improvement of visual outcomes after cataract surgery. (Chin J Ophthalmol, 2017, 53: 514-521)

To investigate the characteristics and distribution of corneal astigmatism before surgery among age-related cataract patients in the Hubei area.

Retrospective study. From January 1, 2012 to July 31, 2016, IOL Master measurements of all qualified cataract surgery candidates were retrospectively collected. Descriptive statistical analysis was used to assess the degree, distribution and type of corneal astigmatism. Kolmogorov-Smirnov (K-S) test was used to evaluate the normal distribution of variables. One-way analysis of variance and Kruskal-Wallis test were applied for the comparison of variance for normally and non-normally distributed quantitative data among different age groups. Spearman's rank test was used to assess the relationship between age and corneal astigmatism.

The mean age of the 2 085 patients (3 586 eyes) involved was (73.1±9.43) years old, with more women (58.3%) than men. The mean value of corneal curvature was 44.33 D (95%CI: 44.28-44.39), and the mean corneal astigmatism was 1.06 D (range, 0.05 D to 6.74 D). K-S test indicated the distribution of corneal curvature was normal (P=0.18), while corneal astigmatism did not obey the normal distribution (P<0.01). Corneal astigmatism was between 0.25 D and 1.25 D in 67.7% of the eyes, >1.25 D in 29.7%, and<0.25 D in 4.2%. Corneal astigmatism degree increased with the age increase ( P<0.01). There was no statistical difference in corneal astigmatism between women and men (P=0.075). However, women had steeper corneal curvatures than men with statistical difference (P<0.01). Corneal astigmatism with the rule was observed in 29.0% of the eyes, while astigmatism against the rule was found in 53.0%. And astigmatism against the rule increased with age.

Corneal astigmatism mostly distributes between 0.25 D and 1.25 D in age-related cataract patients who lived in Hubei. Corneal astigmatism degree increased with age, and the dominant type was astigmatism against the rule. There was no difference in astigmatism between men and women patients aged 50 years and above, but in 70- to 79-year-old patients, women had a higher astigmatism degree than men. The corneal curvature of women was steeper than men in general and in each age group. (Chin J Ophthalmol, 2017, 53: 522-527)

To observe the structure and function of meibomian glands in normal population at different ages.

From October 2011 to August 2012, meibomian gland information was collected in healthy volunteers without any symptoms of ocular discomfort, aged more than 5 years. The people were grouped by every 10 years of age. The meibomian gland opening, secretion state and characteristics and Max's line were observed by slit lamp microscopic examination, and the meibomian gland dropouts were examined by noncontact infrared meibomian gland microscopy. The changes of meibomian glands were scored from 0 to 3, 0 for a normal state, 1 for mild abnormality, 2 for moderate abnormality and 3 for severe abnormality. The Mann-WhitneyU test was used to compare the meibomian scores between male and female, and between left and right eyes. The correlation of these scores and the age of volunteers was analyzed by the Spearman test.

Among all the 100 volunteers, there were 47 males and 53 females, aged from 5 to 83 years (mean, 40.9±22.9). The meibomian gland dropouts were gradually increasing with age, significantly faster after 40 years old (scores for each age group were 2(1), 2(1), 2(1), 2(1), 3(2), 3.5(1.75), 4(3), 6(2). Meibomian gland opening, secretion traits and secretor status gradually became poorer with age, and changes were dramatically fast in the group of 40-49 years of age [scores of this group were 3(1.5), 3(3) and 2(2)], but slowed down after age of 50 years. Moreover, the Max's line position moved to the front gradually with age, with a marked change in the group of 40-49 years of age [scores for each age group were 0(1), 1(1), 2(2), 2(2), 3(2), 2(2), 3(2)], 4 gland changes showed a significantly positive relation to age(r=0.729, 0.635, 0.669, 0.639, 0.470. P<0.01), but not to gender and eye dominance (P>0.05).

Meibomian gland opening and meibomian gland secretion become worse with age. The age of 50 years old is the key period for the meibomian gland changes. (Chin J Ophthalmol, 2017, 53: 528-533)

To evaluate the clinical outcomes of Descemet's membrane endothelial keratoplasty (DMEK) for treatment of patients with corneal endothelial decompensation in China.

Interventional case series. Ten patients (10 eyes) with the diagnosis of corneal endothelial decompensation received DMEK during July 2016 and September 2016 in Zhongshan Ophthalmic Center. Descemet's membrane of the donor tissue was carefully stripped from the underlying stroma manually and cut with a 7.75- or 8.0-mm-diameter donor punch. After stained with 0.06% typan blue, the donor disc loaded on an inserter was gently inserted into the anterior chamber of the recipient. When the rolled graft was unfolded, air was carefully injected into the anterior chamber underneath the graft, so that the graft attached to the stroma of the recipient. All patients were followed up for 3-6 months. The best spectacle corrected visual acuity, the status of donor disc, corneal thickness and corneal endothelial cell density were documented and analyzed.

At 1 day after surgery, 1 donor disc presented a rolled edge, and repeated DMEK surgery was performed for this patient. The remaining 9 donor discs presented in place well. At 1 month after surgery, 7 donor discs were found to well attach to the back surface of the recipient stroma with normal corneal posterior surface using anterior segment optical coherence tomography. The average corneal thickness reduced to (620±67) μm from preoperative (680±78.3) μm ( t=2.677, P=0.025). At 3 months after surgery, 6 patients achieved clear corneas with best spectacle corrected visual acuity ranging from 0.4 to 0.8. The endothelial cell density was 1 342.3±436.5 (872 to 1 933) cells/mm² in the patients with clear corneas. The average corneal thickness reduced to (612±70) μm ( t=2.971, P=0.016).

DMEK could improve visual acuity for corneal endothelial decompensation, but there were more technical difficulties in Chinese eyes. (Chin J Ophthalmol, 2017, 53: 534-539)

To investigate the effect of pigment epithelial-derived factor (PEDF) gene-modified human umbilical cord mesenchymal stem cells (MSC) on rats with diabetic retinopathy (DR).

Experimental study. Human umbilical cord MSC were transfected by lentivirus packaging PEDF-MSC-green fluorescent protein (GFP) and GFP-MSC plasmid vectors, and the expression of PEDF and vascular endothelial growth factor (VEGF) was measured in the cell culture medium. Fifty adult male Sprague-Dawley rats were randomly divided into five groups: normal control group (group A), DR control group (group B), phosphate-buffered saline (PBS) treated group (group C), GFP-MSC treated group (group D) and PEDF-MSC-GFP treated group (group E), with 10 rats in each group. Streptozotocin was intraperitoneally injected to make early DR models. After four-month intervention, groups D and E were given intravitreal injection of GFP-MSC and PEDF-MSC-GFP; group C was given intravitreal injection of phosphate-buffered saline; groups A and B did not receive special treatment. The changes of retina in different groups were detected by hematoxylin and eosin staining, and the thickness of inner plexiform layer, inner nuclear layer and outer nuclear layer was measured by computer-based image analytical system. Immunohistochemistry was applied to observe PEDF and VEGF. Real-time quantitative polymerase chain reaction was used to detect the expression of PEDF and VEGF mRNA.

The expression of CD105, CD73 and CD90 was positive, while the expression of CD34, CD45, CD11b, CD19 and HLA-DR was negative. ELISA results showed that after transfection PEDF protein expression in the supernatant of PEDF-MSC (84.09±7.07) μg/L was higher than the control group (9.03±0.14) μg/L ( P<0.05). At 2 weeks after intravitreal injection, green fluorescence was observed in the rat vitreous of groups D and E under a fluorescence microscope; no obvious green fluorescence was found in the retina. After 2 months of intravitreal injection, the thickness of inner plexiform layer in group E was significantly decreased; the thickness of inner nuclear layer and outer nuclear layer was higher (P<0.05). Immunohistochemical staining showed that 2 months after intravitreal treatment, the average optical density values of PEDF were improved, but the average optical density values of VEGF were decreased in group E (P<0.05). Real-time polymerase chain reaction showed that 2 months after treatment, the expression level of PEDF mRNA in group E was improved, but the expression level of VEGF mRNA was decreased (P<0.05).

Intravitreal injection of PEDF-MSC could up-regulate the expression of PEDF and down-regulate the expression of VEGF in diabetic rats and may represent a novel candidate resource for cell therapy of DR nerve damage. (Chin J Ophthalmol, 2017, 53, 540-547)

The patient was a 50-year-old female. He complained of decreased visual acuity in both eyes for 1 year and deformed vision in his left eye for 1 day. He came to the ophthalmology clinic of Peking Union Medical College Hospital on August 31, 2016. Previous: History of hypertension, diabetes, refractive error, laser exposure denied. Ophthalmic examination: Best corrected visual acuity: 0.6 in right eye and 0.4 in left eye. The cornea of both eyes is transparent, the front is deep, there is no plankton and aqueous humor flash, the pupil is round, the light reflection is good, and the lens is slightly opaque. Both eyes were dilated to check the fundus: the optic discs of both eyes were normal, and scattered yellow-white dots and clusters of crystalline substances were seen in the retina on the temporal side of the optic disc and around the fovea. The reflection of the fovea of the right eye was visible, but the reflection of the fovea of the left eye was not visible, and the rest was roughly normal (Figure 1）。 Frequency domain OCT showed thinning of retinal nerve fiber layer in both eyes, loss of optic nerve fiber in foveal macula showed pseudocystoid vacuolar change, accompanied by rupture and loss of ellipsoid band, and crystalline substance showed hyperreflective signal (Figure 2）。 Autofluorescence revealed hypofluorescence in the crystalline substance deposited areas of both eyes, accompanied by punctate hyperfluorescence, and clustered hypofluorescence in the concave spots in the center of the macula (Figure 3）。 The results of FFA examination showed fluorescein leakage in the macular area of both eyes in the early stage, high fluorescence in the crystal-like substance deposition area, dye accumulation in the macular area in the late stage, and fluorescence decreased in the crystal-like substance deposition area (Figure 4), suggesting mild cystoid edema of the macula in both eyes. The 30° visual field shows a relatively dark spot below the left eye, and the visual field of the right eye is roughly normal. Further inquiry about the medical history showed that the patient had undergone breast cancer resection 3 and a half years ago, and started to take tamoxifen 20 mg/d orally after the operation, with a cumulative total of 25.6g in 3 and a half years. Diagnosis: Tamoxifen retinopathy in both eyes, complicated cataract in both eyes. Then ask an oncologist for consultation, give medication, stop tamoxifen, and change to toremifene tablets for oral administration.

The patient was an 82-year-old male. Because of blurred vision in his right eye for more than 1 year, he went to Fuzhou Southeast Eye Hospital. Previous 2 years ago acute primary angle closure glaucoma in both eyes, the right eye underwent compound trabeculectomy, and the left eye underwent peripheral iridectomy. Ocular examination: Right eye naked visual acuity 0.12, corrected visual acuity 0.4, intraocular pressure 12 mmHg (1 mmHg =0.133 kPa), mild conjunctival hyperemia, large and crystal clear filter vesicles visible above (Quintessence Picture 1), thin-walled, overhanging, approximately 4 mm ×4 mm in size, fluorescein staining (-); The cornea is transparent, retrocorneal sediment (-), the central anterior chamber is deep, the aqueous humor flashes (-), the periiris incision is faintly visible above, the pupil is dilated and underround, the reflection of light is slow, the lens is moderately opaque, the fundus optic disc is pale in color, the cup-to-disc ratio is 0.8, the arteriovenous diameter ratio is 1:2, and the foveal reflection is visible. Clinical diagnosis: Primary angle closure glaucoma in both eyes after anti-glaucoma surgery; Complicated cataract of the right eye.

Divergence insufficiency is acquired esotropia at distance fixation with symptomatic uncrossed diplopia but fusion at near. It can be divided into two forms: primary isolated form and secondary form associated with neurologic abnormalities, also called divergence palsy. The clinical features of divergence insufficiency include small esotropia only at distance but orthotropia or small esophoria at near, comitant deviation at lateral gaze, reduced divergence fusion, full abduction and normal saccadic velocities in abduction. Primary divergence insufficiency is a benign condition predominantly occurring in adults older than 50 years. Recently, studies on the etiology of age-related distance esotropia, also called sagging eye syndrome, have demonstrated that the degenerative changes of orbital tissue could induce the inferior displacement of the inferior rectus pulley, different from the neurological etiology in abducens nerve palsy and secondary divergence insufficiency. The treatment goal is to relieve diplopia. Both prism and regular surgeries including medial rectus recession and lateral rectus resection are effective. Some unusual surgeries have been applied in divergence insufficiency, but further investigations with large samples are needed. The recent research advances in the etiology, diagnosis, differential diagnosis and treatment of divergence insufficiency are reviewed in this article. (Chin J Ophthalmol, 2017, 53: 552-556)